1 /* 2 * pcap-linux.c: Packet capture interface to the Linux kernel 3 * 4 * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org> 5 * Sebastian Krahmer <krahmer@cs.uni-potsdam.de> 6 * 7 * License: BSD 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 3. The names of the authors may not be used to endorse or promote 20 * products derived from this software without specific prior 21 * written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 26 * 27 * Modifications: Added PACKET_MMAP support 28 * Paolo Abeni <paolo.abeni@email.it> 29 * 30 * based on previous works of: 31 * Simon Patarin <patarin@cs.unibo.it> 32 * Phil Wood <cpw@lanl.gov> 33 * 34 * Monitor-mode support for mac80211 includes code taken from the iw 35 * command; the copyright notice for that code is 36 * 37 * Copyright (c) 2007, 2008 Johannes Berg 38 * Copyright (c) 2007 Andy Lutomirski 39 * Copyright (c) 2007 Mike Kershaw 40 * Copyright (c) 2008 Gábor Stefanik 41 * 42 * All rights reserved. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 1. Redistributions of source code must retain the above copyright 48 * notice, this list of conditions and the following disclaimer. 49 * 2. Redistributions in binary form must reproduce the above copyright 50 * notice, this list of conditions and the following disclaimer in the 51 * documentation and/or other materials provided with the distribution. 52 * 3. The name of the author may not be used to endorse or promote products 53 * derived from this software without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 56 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 57 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 58 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 59 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 60 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 61 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 62 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 63 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 */ 67 68 #ifndef lint 69 static const char rcsid[] _U_ = 70 "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.164 2008-12-14 22:00:57 guy Exp $ (LBL)"; 71 #endif 72 73 /* 74 * Known problems with 2.0[.x] kernels: 75 * 76 * - The loopback device gives every packet twice; on 2.2[.x] kernels, 77 * if we use PF_PACKET, we can filter out the transmitted version 78 * of the packet by using data in the "sockaddr_ll" returned by 79 * "recvfrom()", but, on 2.0[.x] kernels, we have to use 80 * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a 81 * "sockaddr_pkt" which doesn't give us enough information to let 82 * us do that. 83 * 84 * - We have to set the interface's IFF_PROMISC flag ourselves, if 85 * we're to run in promiscuous mode, which means we have to turn 86 * it off ourselves when we're done; the kernel doesn't keep track 87 * of how many sockets are listening promiscuously, which means 88 * it won't get turned off automatically when no sockets are 89 * listening promiscuously. We catch "pcap_close()" and, for 90 * interfaces we put into promiscuous mode, take them out of 91 * promiscuous mode - which isn't necessarily the right thing to 92 * do, if another socket also requested promiscuous mode between 93 * the time when we opened the socket and the time when we close 94 * the socket. 95 * 96 * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()" 97 * return the amount of data that you could have read, rather than 98 * the amount that was returned, so we can't just allocate a buffer 99 * whose size is the snapshot length and pass the snapshot length 100 * as the byte count, and also pass MSG_TRUNC, so that the return 101 * value tells us how long the packet was on the wire. 102 * 103 * This means that, if we want to get the actual size of the packet, 104 * so we can return it in the "len" field of the packet header, 105 * we have to read the entire packet, not just the part that fits 106 * within the snapshot length, and thus waste CPU time copying data 107 * from the kernel that our caller won't see. 108 * 109 * We have to get the actual size, and supply it in "len", because 110 * otherwise, the IP dissector in tcpdump, for example, will complain 111 * about "truncated-ip", as the packet will appear to have been 112 * shorter, on the wire, than the IP header said it should have been. 113 */ 114 115 116 #define _GNU_SOURCE 117 118 #ifdef HAVE_CONFIG_H 119 #include "config.h" 120 #endif 121 122 #include <errno.h> 123 #include <stdio.h> 124 #include <stdlib.h> 125 #include <ctype.h> 126 #include <unistd.h> 127 #include <fcntl.h> 128 #include <string.h> 129 #include <limits.h> 130 #include <sys/socket.h> 131 #include <sys/ioctl.h> 132 #include <sys/utsname.h> 133 #include <sys/mman.h> 134 #include <linux/if.h> 135 #include <netinet/in.h> 136 #include <linux/if_ether.h> 137 #include <net/if_arp.h> 138 #include <poll.h> 139 #include <dirent.h> 140 141 #include "pcap-int.h" 142 #include "pcap/sll.h" 143 #include "pcap/vlan.h" 144 145 #ifdef HAVE_DAG_API 146 #include "pcap-dag.h" 147 #endif /* HAVE_DAG_API */ 148 149 #ifdef HAVE_SEPTEL_API 150 #include "pcap-septel.h" 151 #endif /* HAVE_SEPTEL_API */ 152 153 #ifdef HAVE_SNF_API 154 #include "pcap-snf.h" 155 #endif /* HAVE_SNF_API */ 156 157 #ifdef PCAP_SUPPORT_USB 158 #include "pcap-usb-linux.h" 159 #endif 160 161 #ifdef PCAP_SUPPORT_BT 162 #include "pcap-bt-linux.h" 163 #endif 164 165 #ifdef PCAP_SUPPORT_CAN 166 #include "pcap-can-linux.h" 167 #endif 168 169 #if PCAP_SUPPORT_CANUSB 170 #include "pcap-canusb-linux.h" 171 #endif 172 173 #ifdef PCAP_SUPPORT_NETFILTER 174 #include "pcap-netfilter-linux.h" 175 #endif 176 177 /* 178 * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET 179 * sockets rather than SOCK_PACKET sockets. 180 * 181 * To use them, we include <linux/if_packet.h> rather than 182 * <netpacket/packet.h>; we do so because 183 * 184 * some Linux distributions (e.g., Slackware 4.0) have 2.2 or 185 * later kernels and libc5, and don't provide a <netpacket/packet.h> 186 * file; 187 * 188 * not all versions of glibc2 have a <netpacket/packet.h> file 189 * that defines stuff needed for some of the 2.4-or-later-kernel 190 * features, so if the system has a 2.4 or later kernel, we 191 * still can't use those features. 192 * 193 * We're already including a number of other <linux/XXX.h> headers, and 194 * this code is Linux-specific (no other OS has PF_PACKET sockets as 195 * a raw packet capture mechanism), so it's not as if you gain any 196 * useful portability by using <netpacket/packet.h> 197 * 198 * XXX - should we just include <linux/if_packet.h> even if PF_PACKET 199 * isn't defined? It only defines one data structure in 2.0.x, so 200 * it shouldn't cause any problems. 201 */ 202 #ifdef PF_PACKET 203 # include <linux/if_packet.h> 204 205 /* 206 * On at least some Linux distributions (for example, Red Hat 5.2), 207 * there's no <netpacket/packet.h> file, but PF_PACKET is defined if 208 * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define 209 * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of 210 * the PACKET_xxx stuff. 211 * 212 * So we check whether PACKET_HOST is defined, and assume that we have 213 * PF_PACKET sockets only if it is defined. 214 */ 215 # ifdef PACKET_HOST 216 # define HAVE_PF_PACKET_SOCKETS 217 # ifdef PACKET_AUXDATA 218 # define HAVE_PACKET_AUXDATA 219 # endif /* PACKET_AUXDATA */ 220 # endif /* PACKET_HOST */ 221 222 223 /* check for memory mapped access avaibility. We assume every needed 224 * struct is defined if the macro TPACKET_HDRLEN is defined, because it 225 * uses many ring related structs and macros */ 226 # ifdef TPACKET_HDRLEN 227 # define HAVE_PACKET_RING 228 # ifdef TPACKET2_HDRLEN 229 # define HAVE_TPACKET2 230 # else 231 # define TPACKET_V1 0 232 # endif /* TPACKET2_HDRLEN */ 233 # endif /* TPACKET_HDRLEN */ 234 #endif /* PF_PACKET */ 235 236 #ifdef SO_ATTACH_FILTER 237 #include <linux/types.h> 238 #include <linux/filter.h> 239 #endif 240 241 /* 242 * We need linux/sockios.h if we have linux/net_tstamp.h (for time stamp 243 * specification) or linux/ethtool.h (for ethtool ioctls to get offloading 244 * information). 245 */ 246 #if defined(HAVE_LINUX_NET_TSTAMP_H) || defined(HAVE_LINUX_ETHTOOL_H) 247 #include <linux/sockios.h> 248 #endif 249 250 #ifdef HAVE_LINUX_NET_TSTAMP_H 251 #include <linux/net_tstamp.h> 252 #endif 253 254 /* 255 * Got Wireless Extensions? 256 */ 257 #ifdef HAVE_LINUX_WIRELESS_H 258 #include <linux/wireless.h> 259 #endif /* HAVE_LINUX_WIRELESS_H */ 260 261 /* 262 * Got libnl? 263 */ 264 #ifdef HAVE_LIBNL 265 #include <linux/nl80211.h> 266 267 #include <netlink/genl/genl.h> 268 #include <netlink/genl/family.h> 269 #include <netlink/genl/ctrl.h> 270 #include <netlink/msg.h> 271 #include <netlink/attr.h> 272 #endif /* HAVE_LIBNL */ 273 274 /* 275 * Got ethtool support? 276 */ 277 #ifdef HAVE_LINUX_ETHTOOL_H 278 #include <linux/ethtool.h> 279 #endif 280 281 #ifndef HAVE_SOCKLEN_T 282 typedef int socklen_t; 283 #endif 284 285 #ifndef MSG_TRUNC 286 /* 287 * This is being compiled on a system that lacks MSG_TRUNC; define it 288 * with the value it has in the 2.2 and later kernels, so that, on 289 * those kernels, when we pass it in the flags argument to "recvfrom()" 290 * we're passing the right value and thus get the MSG_TRUNC behavior 291 * we want. (We don't get that behavior on 2.0[.x] kernels, because 292 * they didn't support MSG_TRUNC.) 293 */ 294 #define MSG_TRUNC 0x20 295 #endif 296 297 #ifndef SOL_PACKET 298 /* 299 * This is being compiled on a system that lacks SOL_PACKET; define it 300 * with the value it has in the 2.2 and later kernels, so that we can 301 * set promiscuous mode in the good modern way rather than the old 302 * 2.0-kernel crappy way. 303 */ 304 #define SOL_PACKET 263 305 #endif 306 307 #define MAX_LINKHEADER_SIZE 256 308 309 /* 310 * When capturing on all interfaces we use this as the buffer size. 311 * Should be bigger then all MTUs that occur in real life. 312 * 64kB should be enough for now. 313 */ 314 #define BIGGER_THAN_ALL_MTUS (64*1024) 315 316 /* 317 * Prototypes for internal functions and methods. 318 */ 319 static void map_arphrd_to_dlt(pcap_t *, int, int); 320 #ifdef HAVE_PF_PACKET_SOCKETS 321 static short int map_packet_type_to_sll_type(short int); 322 #endif 323 static int pcap_activate_linux(pcap_t *); 324 static int activate_old(pcap_t *); 325 static int activate_new(pcap_t *); 326 static int activate_mmap(pcap_t *, int *); 327 static int pcap_can_set_rfmon_linux(pcap_t *); 328 static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *); 329 static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); 330 static int pcap_inject_linux(pcap_t *, const void *, size_t); 331 static int pcap_stats_linux(pcap_t *, struct pcap_stat *); 332 static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); 333 static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); 334 static void pcap_cleanup_linux(pcap_t *); 335 336 union thdr { 337 struct tpacket_hdr *h1; 338 struct tpacket2_hdr *h2; 339 void *raw; 340 }; 341 342 #ifdef HAVE_PACKET_RING 343 #define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset]) 344 345 static void destroy_ring(pcap_t *handle); 346 static int create_ring(pcap_t *handle, int *status); 347 static int prepare_tpacket_socket(pcap_t *handle); 348 static void pcap_cleanup_linux_mmap(pcap_t *); 349 static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *); 350 static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); 351 static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf); 352 static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf); 353 static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, 354 const u_char *bytes); 355 #endif 356 357 /* 358 * Wrap some ioctl calls 359 */ 360 #ifdef HAVE_PF_PACKET_SOCKETS 361 static int iface_get_id(int fd, const char *device, char *ebuf); 362 #endif /* HAVE_PF_PACKET_SOCKETS */ 363 static int iface_get_mtu(int fd, const char *device, char *ebuf); 364 static int iface_get_arptype(int fd, const char *device, char *ebuf); 365 #ifdef HAVE_PF_PACKET_SOCKETS 366 static int iface_bind(int fd, int ifindex, char *ebuf); 367 #ifdef IW_MODE_MONITOR 368 static int has_wext(int sock_fd, const char *device, char *ebuf); 369 #endif /* IW_MODE_MONITOR */ 370 static int enter_rfmon_mode(pcap_t *handle, int sock_fd, 371 const char *device); 372 #endif /* HAVE_PF_PACKET_SOCKETS */ 373 static int iface_get_offload(pcap_t *handle); 374 static int iface_bind_old(int fd, const char *device, char *ebuf); 375 376 #ifdef SO_ATTACH_FILTER 377 static int fix_program(pcap_t *handle, struct sock_fprog *fcode, 378 int is_mapped); 379 static int fix_offset(struct bpf_insn *p); 380 static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); 381 static int reset_kernel_filter(pcap_t *handle); 382 383 static struct sock_filter total_insn 384 = BPF_STMT(BPF_RET | BPF_K, 0); 385 static struct sock_fprog total_fcode 386 = { 1, &total_insn }; 387 #endif /* SO_ATTACH_FILTER */ 388 389 pcap_t * 390 pcap_create(const char *device, char *ebuf) 391 { 392 pcap_t *handle; 393 394 /* 395 * A null device name is equivalent to the "any" device. 396 */ 397 if (device == NULL) 398 device = "any"; 399 400 #ifdef HAVE_DAG_API 401 if (strstr(device, "dag")) { 402 return dag_create(device, ebuf); 403 } 404 #endif /* HAVE_DAG_API */ 405 406 #ifdef HAVE_SEPTEL_API 407 if (strstr(device, "septel")) { 408 return septel_create(device, ebuf); 409 } 410 #endif /* HAVE_SEPTEL_API */ 411 412 #ifdef HAVE_SNF_API 413 handle = snf_create(device, ebuf); 414 if (strstr(device, "snf") || handle != NULL) 415 return handle; 416 417 #endif /* HAVE_SNF_API */ 418 419 #ifdef PCAP_SUPPORT_BT 420 if (strstr(device, "bluetooth")) { 421 return bt_create(device, ebuf); 422 } 423 #endif 424 425 #if PCAP_SUPPORT_CANUSB 426 if (strstr(device, "canusb")) { 427 return canusb_create(device, ebuf); 428 } 429 #endif 430 431 #ifdef PCAP_SUPPORT_CAN 432 if ((strncmp(device, "can", 3) == 0 && isdigit(device[3])) || 433 (strncmp(device, "vcan", 4) == 0 && isdigit(device[4]))) { 434 return can_create(device, ebuf); 435 } 436 #endif 437 438 #ifdef PCAP_SUPPORT_USB 439 if (strstr(device, "usbmon")) { 440 return usb_create(device, ebuf); 441 } 442 #endif 443 444 #ifdef PCAP_SUPPORT_NETFILTER 445 if (strncmp(device, "nflog", strlen("nflog")) == 0) { 446 return nflog_create(device, ebuf); 447 } 448 #endif 449 450 handle = pcap_create_common(device, ebuf); 451 if (handle == NULL) 452 return NULL; 453 454 handle->activate_op = pcap_activate_linux; 455 handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; 456 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) 457 /* 458 * We claim that we support: 459 * 460 * software time stamps, with no details about their precision; 461 * hardware time stamps, synced to the host time; 462 * hardware time stamps, not synced to the host time. 463 * 464 * XXX - we can't ask a device whether it supports 465 * hardware time stamps, so we just claim all devices do. 466 */ 467 handle->tstamp_type_count = 3; 468 handle->tstamp_type_list = malloc(3 * sizeof(u_int)); 469 if (handle->tstamp_type_list == NULL) { 470 free(handle); 471 return NULL; 472 } 473 handle->tstamp_type_list[0] = PCAP_TSTAMP_HOST; 474 handle->tstamp_type_list[1] = PCAP_TSTAMP_ADAPTER; 475 handle->tstamp_type_list[2] = PCAP_TSTAMP_ADAPTER_UNSYNCED; 476 #endif 477 478 return handle; 479 } 480 481 #ifdef HAVE_LIBNL 482 /* 483 * If interface {if} is a mac80211 driver, the file 484 * /sys/class/net/{if}/phy80211 is a symlink to 485 * /sys/class/ieee80211/{phydev}, for some {phydev}. 486 * 487 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at 488 * least, has a "wmaster0" device and a "wlan0" device; the 489 * latter is the one with the IP address. Both show up in 490 * "tcpdump -D" output. Capturing on the wmaster0 device 491 * captures with 802.11 headers. 492 * 493 * airmon-ng searches through /sys/class/net for devices named 494 * monN, starting with mon0; as soon as one *doesn't* exist, 495 * it chooses that as the monitor device name. If the "iw" 496 * command exists, it does "iw dev {if} interface add {monif} 497 * type monitor", where {monif} is the monitor device. It 498 * then (sigh) sleeps .1 second, and then configures the 499 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface 500 * is a file, it writes {mondev}, without a newline, to that file, 501 * and again (sigh) sleeps .1 second, and then iwconfig's that 502 * device into monitor mode and configures it up. Otherwise, 503 * you can't do monitor mode. 504 * 505 * All these devices are "glued" together by having the 506 * /sys/class/net/{device}/phy80211 links pointing to the same 507 * place, so, given a wmaster, wlan, or mon device, you can 508 * find the other devices by looking for devices with 509 * the same phy80211 link. 510 * 511 * To turn monitor mode off, delete the monitor interface, 512 * either with "iw dev {monif} interface del" or by sending 513 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface 514 * 515 * Note: if you try to create a monitor device named "monN", and 516 * there's already a "monN" device, it fails, as least with 517 * the netlink interface (which is what iw uses), with a return 518 * value of -ENFILE. (Return values are negative errnos.) We 519 * could probably use that to find an unused device. 520 * 521 * Yes, you can have multiple monitor devices for a given 522 * physical device. 523 */ 524 525 /* 526 * Is this a mac80211 device? If so, fill in the physical device path and 527 * return 1; if not, return 0. On an error, fill in handle->errbuf and 528 * return PCAP_ERROR. 529 */ 530 static int 531 get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, 532 size_t phydev_max_pathlen) 533 { 534 char *pathstr; 535 ssize_t bytes_read; 536 537 /* 538 * Generate the path string for the symlink to the physical device. 539 */ 540 if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { 541 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 542 "%s: Can't generate path name string for /sys/class/net device", 543 device); 544 return PCAP_ERROR; 545 } 546 bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); 547 if (bytes_read == -1) { 548 if (errno == ENOENT || errno == EINVAL) { 549 /* 550 * Doesn't exist, or not a symlink; assume that 551 * means it's not a mac80211 device. 552 */ 553 free(pathstr); 554 return 0; 555 } 556 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 557 "%s: Can't readlink %s: %s", device, pathstr, 558 strerror(errno)); 559 free(pathstr); 560 return PCAP_ERROR; 561 } 562 free(pathstr); 563 phydev_path[bytes_read] = '\0'; 564 return 1; 565 } 566 567 #ifdef HAVE_LIBNL_2_x 568 #define get_nl_errmsg nl_geterror 569 #else 570 /* libnl 2.x compatibility code */ 571 572 #define nl_sock nl_handle 573 574 static inline struct nl_handle * 575 nl_socket_alloc(void) 576 { 577 return nl_handle_alloc(); 578 } 579 580 static inline void 581 nl_socket_free(struct nl_handle *h) 582 { 583 nl_handle_destroy(h); 584 } 585 586 #define get_nl_errmsg strerror 587 588 static inline int 589 __genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache) 590 { 591 struct nl_cache *tmp = genl_ctrl_alloc_cache(h); 592 if (!tmp) 593 return -ENOMEM; 594 *cache = tmp; 595 return 0; 596 } 597 #define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache 598 #endif /* !HAVE_LIBNL_2_x */ 599 600 struct nl80211_state { 601 struct nl_sock *nl_sock; 602 struct nl_cache *nl_cache; 603 struct genl_family *nl80211; 604 }; 605 606 static int 607 nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) 608 { 609 int err; 610 611 state->nl_sock = nl_socket_alloc(); 612 if (!state->nl_sock) { 613 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 614 "%s: failed to allocate netlink handle", device); 615 return PCAP_ERROR; 616 } 617 618 if (genl_connect(state->nl_sock)) { 619 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 620 "%s: failed to connect to generic netlink", device); 621 goto out_handle_destroy; 622 } 623 624 err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache); 625 if (err < 0) { 626 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 627 "%s: failed to allocate generic netlink cache: %s", 628 device, get_nl_errmsg(-err)); 629 goto out_handle_destroy; 630 } 631 632 state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); 633 if (!state->nl80211) { 634 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 635 "%s: nl80211 not found", device); 636 goto out_cache_free; 637 } 638 639 return 0; 640 641 out_cache_free: 642 nl_cache_free(state->nl_cache); 643 out_handle_destroy: 644 nl_socket_free(state->nl_sock); 645 return PCAP_ERROR; 646 } 647 648 static void 649 nl80211_cleanup(struct nl80211_state *state) 650 { 651 genl_family_put(state->nl80211); 652 nl_cache_free(state->nl_cache); 653 nl_socket_free(state->nl_sock); 654 } 655 656 static int 657 add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, 658 const char *device, const char *mondevice) 659 { 660 int ifindex; 661 struct nl_msg *msg; 662 int err; 663 664 ifindex = iface_get_id(sock_fd, device, handle->errbuf); 665 if (ifindex == -1) 666 return PCAP_ERROR; 667 668 msg = nlmsg_alloc(); 669 if (!msg) { 670 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 671 "%s: failed to allocate netlink msg", device); 672 return PCAP_ERROR; 673 } 674 675 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 676 0, NL80211_CMD_NEW_INTERFACE, 0); 677 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); 678 NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); 679 NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); 680 681 err = nl_send_auto_complete(state->nl_sock, msg); 682 if (err < 0) { 683 #ifdef HAVE_LIBNL_2_x 684 if (err == -NLE_FAILURE) { 685 #else 686 if (err == -ENFILE) { 687 #endif 688 /* 689 * Device not available; our caller should just 690 * keep trying. (libnl 2.x maps ENFILE to 691 * NLE_FAILURE; it can also map other errors 692 * to that, but there's not much we can do 693 * about that.) 694 */ 695 nlmsg_free(msg); 696 return 0; 697 } else { 698 /* 699 * Real failure, not just "that device is not 700 * available. 701 */ 702 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 703 "%s: nl_send_auto_complete failed adding %s interface: %s", 704 device, mondevice, get_nl_errmsg(-err)); 705 nlmsg_free(msg); 706 return PCAP_ERROR; 707 } 708 } 709 err = nl_wait_for_ack(state->nl_sock); 710 if (err < 0) { 711 #ifdef HAVE_LIBNL_2_x 712 if (err == -NLE_FAILURE) { 713 #else 714 if (err == -ENFILE) { 715 #endif 716 /* 717 * Device not available; our caller should just 718 * keep trying. (libnl 2.x maps ENFILE to 719 * NLE_FAILURE; it can also map other errors 720 * to that, but there's not much we can do 721 * about that.) 722 */ 723 nlmsg_free(msg); 724 return 0; 725 } else { 726 /* 727 * Real failure, not just "that device is not 728 * available. 729 */ 730 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 731 "%s: nl_wait_for_ack failed adding %s interface: %s", 732 device, mondevice, get_nl_errmsg(-err)); 733 nlmsg_free(msg); 734 return PCAP_ERROR; 735 } 736 } 737 738 /* 739 * Success. 740 */ 741 nlmsg_free(msg); 742 return 1; 743 744 nla_put_failure: 745 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 746 "%s: nl_put failed adding %s interface", 747 device, mondevice); 748 nlmsg_free(msg); 749 return PCAP_ERROR; 750 } 751 752 static int 753 del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, 754 const char *device, const char *mondevice) 755 { 756 int ifindex; 757 struct nl_msg *msg; 758 int err; 759 760 ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); 761 if (ifindex == -1) 762 return PCAP_ERROR; 763 764 msg = nlmsg_alloc(); 765 if (!msg) { 766 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 767 "%s: failed to allocate netlink msg", device); 768 return PCAP_ERROR; 769 } 770 771 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 772 0, NL80211_CMD_DEL_INTERFACE, 0); 773 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); 774 775 err = nl_send_auto_complete(state->nl_sock, msg); 776 if (err < 0) { 777 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 778 "%s: nl_send_auto_complete failed deleting %s interface: %s", 779 device, mondevice, get_nl_errmsg(-err)); 780 nlmsg_free(msg); 781 return PCAP_ERROR; 782 } 783 err = nl_wait_for_ack(state->nl_sock); 784 if (err < 0) { 785 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 786 "%s: nl_wait_for_ack failed adding %s interface: %s", 787 device, mondevice, get_nl_errmsg(-err)); 788 nlmsg_free(msg); 789 return PCAP_ERROR; 790 } 791 792 /* 793 * Success. 794 */ 795 nlmsg_free(msg); 796 return 1; 797 798 nla_put_failure: 799 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 800 "%s: nl_put failed deleting %s interface", 801 device, mondevice); 802 nlmsg_free(msg); 803 return PCAP_ERROR; 804 } 805 806 static int 807 enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) 808 { 809 int ret; 810 char phydev_path[PATH_MAX+1]; 811 struct nl80211_state nlstate; 812 struct ifreq ifr; 813 u_int n; 814 815 /* 816 * Is this a mac80211 device? 817 */ 818 ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); 819 if (ret < 0) 820 return ret; /* error */ 821 if (ret == 0) 822 return 0; /* no error, but not mac80211 device */ 823 824 /* 825 * XXX - is this already a monN device? 826 * If so, we're done. 827 * Is that determined by old Wireless Extensions ioctls? 828 */ 829 830 /* 831 * OK, it's apparently a mac80211 device. 832 * Try to find an unused monN device for it. 833 */ 834 ret = nl80211_init(handle, &nlstate, device); 835 if (ret != 0) 836 return ret; 837 for (n = 0; n < UINT_MAX; n++) { 838 /* 839 * Try mon{n}. 840 */ 841 char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ 842 843 snprintf(mondevice, sizeof mondevice, "mon%u", n); 844 ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); 845 if (ret == 1) { 846 handle->md.mondevice = strdup(mondevice); 847 goto added; 848 } 849 if (ret < 0) { 850 /* 851 * Hard failure. Just return ret; handle->errbuf 852 * has already been set. 853 */ 854 nl80211_cleanup(&nlstate); 855 return ret; 856 } 857 } 858 859 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 860 "%s: No free monN interfaces", device); 861 nl80211_cleanup(&nlstate); 862 return PCAP_ERROR; 863 864 added: 865 866 #if 0 867 /* 868 * Sleep for .1 seconds. 869 */ 870 delay.tv_sec = 0; 871 delay.tv_nsec = 500000000; 872 nanosleep(&delay, NULL); 873 #endif 874 875 /* 876 * If we haven't already done so, arrange to have 877 * "pcap_close_all()" called when we exit. 878 */ 879 if (!pcap_do_addexit(handle)) { 880 /* 881 * "atexit()" failed; don't put the interface 882 * in rfmon mode, just give up. 883 */ 884 return PCAP_ERROR_RFMON_NOTSUP; 885 } 886 887 /* 888 * Now configure the monitor interface up. 889 */ 890 memset(&ifr, 0, sizeof(ifr)); 891 strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name)); 892 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { 893 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 894 "%s: Can't get flags for %s: %s", device, 895 handle->md.mondevice, strerror(errno)); 896 del_mon_if(handle, sock_fd, &nlstate, device, 897 handle->md.mondevice); 898 nl80211_cleanup(&nlstate); 899 return PCAP_ERROR; 900 } 901 ifr.ifr_flags |= IFF_UP|IFF_RUNNING; 902 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 903 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 904 "%s: Can't set flags for %s: %s", device, 905 handle->md.mondevice, strerror(errno)); 906 del_mon_if(handle, sock_fd, &nlstate, device, 907 handle->md.mondevice); 908 nl80211_cleanup(&nlstate); 909 return PCAP_ERROR; 910 } 911 912 /* 913 * Success. Clean up the libnl state. 914 */ 915 nl80211_cleanup(&nlstate); 916 917 /* 918 * Note that we have to delete the monitor device when we close 919 * the handle. 920 */ 921 handle->md.must_do_on_close |= MUST_DELETE_MONIF; 922 923 /* 924 * Add this to the list of pcaps to close when we exit. 925 */ 926 pcap_add_to_pcaps_to_close(handle); 927 928 return 1; 929 } 930 #endif /* HAVE_LIBNL */ 931 932 static int 933 pcap_can_set_rfmon_linux(pcap_t *handle) 934 { 935 #ifdef HAVE_LIBNL 936 char phydev_path[PATH_MAX+1]; 937 int ret; 938 #endif 939 #ifdef IW_MODE_MONITOR 940 int sock_fd; 941 struct iwreq ireq; 942 #endif 943 944 if (strcmp(handle->opt.source, "any") == 0) { 945 /* 946 * Monitor mode makes no sense on the "any" device. 947 */ 948 return 0; 949 } 950 951 #ifdef HAVE_LIBNL 952 /* 953 * Bleah. There doesn't seem to be a way to ask a mac80211 954 * device, through libnl, whether it supports monitor mode; 955 * we'll just check whether the device appears to be a 956 * mac80211 device and, if so, assume the device supports 957 * monitor mode. 958 * 959 * wmaster devices don't appear to support the Wireless 960 * Extensions, but we can create a mon device for a 961 * wmaster device, so we don't bother checking whether 962 * a mac80211 device supports the Wireless Extensions. 963 */ 964 ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path, 965 PATH_MAX); 966 if (ret < 0) 967 return ret; /* error */ 968 if (ret == 1) 969 return 1; /* mac80211 device */ 970 #endif 971 972 #ifdef IW_MODE_MONITOR 973 /* 974 * Bleah. There doesn't appear to be an ioctl to use to ask 975 * whether a device supports monitor mode; we'll just do 976 * SIOCGIWMODE and, if it succeeds, assume the device supports 977 * monitor mode. 978 * 979 * Open a socket on which to attempt to get the mode. 980 * (We assume that if we have Wireless Extensions support 981 * we also have PF_PACKET support.) 982 */ 983 sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); 984 if (sock_fd == -1) { 985 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 986 "socket: %s", pcap_strerror(errno)); 987 return PCAP_ERROR; 988 } 989 990 /* 991 * Attempt to get the current mode. 992 */ 993 strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source, 994 sizeof ireq.ifr_ifrn.ifrn_name); 995 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 996 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { 997 /* 998 * Well, we got the mode; assume we can set it. 999 */ 1000 close(sock_fd); 1001 return 1; 1002 } 1003 if (errno == ENODEV) { 1004 /* The device doesn't even exist. */ 1005 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1006 "SIOCGIWMODE failed: %s", pcap_strerror(errno)); 1007 close(sock_fd); 1008 return PCAP_ERROR_NO_SUCH_DEVICE; 1009 } 1010 close(sock_fd); 1011 #endif 1012 return 0; 1013 } 1014 1015 /* 1016 * Grabs the number of dropped packets by the interface from /proc/net/dev. 1017 * 1018 * XXX - what about /sys/class/net/{interface name}/rx_*? There are 1019 * individual devices giving, in ASCII, various rx_ and tx_ statistics. 1020 * 1021 * Or can we get them in binary form from netlink? 1022 */ 1023 static long int 1024 linux_if_drops(const char * if_name) 1025 { 1026 char buffer[512]; 1027 char * bufptr; 1028 FILE * file; 1029 int field_to_convert = 3, if_name_sz = strlen(if_name); 1030 long int dropped_pkts = 0; 1031 1032 file = fopen("/proc/net/dev", "r"); 1033 if (!file) 1034 return 0; 1035 1036 while (!dropped_pkts && fgets( buffer, sizeof(buffer), file )) 1037 { 1038 /* search for 'bytes' -- if its in there, then 1039 that means we need to grab the fourth field. otherwise 1040 grab the third field. */ 1041 if (field_to_convert != 4 && strstr(buffer, "bytes")) 1042 { 1043 field_to_convert = 4; 1044 continue; 1045 } 1046 1047 /* find iface and make sure it actually matches -- space before the name and : after it */ 1048 if ((bufptr = strstr(buffer, if_name)) && 1049 (bufptr == buffer || *(bufptr-1) == ' ') && 1050 *(bufptr + if_name_sz) == ':') 1051 { 1052 bufptr = bufptr + if_name_sz + 1; 1053 1054 /* grab the nth field from it */ 1055 while( --field_to_convert && *bufptr != '\0') 1056 { 1057 while (*bufptr != '\0' && *(bufptr++) == ' '); 1058 while (*bufptr != '\0' && *(bufptr++) != ' '); 1059 } 1060 1061 /* get rid of any final spaces */ 1062 while (*bufptr != '\0' && *bufptr == ' ') bufptr++; 1063 1064 if (*bufptr != '\0') 1065 dropped_pkts = strtol(bufptr, NULL, 10); 1066 1067 break; 1068 } 1069 } 1070 1071 fclose(file); 1072 return dropped_pkts; 1073 } 1074 1075 1076 /* 1077 * With older kernels promiscuous mode is kind of interesting because we 1078 * have to reset the interface before exiting. The problem can't really 1079 * be solved without some daemon taking care of managing usage counts. 1080 * If we put the interface into promiscuous mode, we set a flag indicating 1081 * that we must take it out of that mode when the interface is closed, 1082 * and, when closing the interface, if that flag is set we take it out 1083 * of promiscuous mode. 1084 * 1085 * Even with newer kernels, we have the same issue with rfmon mode. 1086 */ 1087 1088 static void pcap_cleanup_linux( pcap_t *handle ) 1089 { 1090 struct ifreq ifr; 1091 #ifdef HAVE_LIBNL 1092 struct nl80211_state nlstate; 1093 int ret; 1094 #endif /* HAVE_LIBNL */ 1095 #ifdef IW_MODE_MONITOR 1096 int oldflags; 1097 struct iwreq ireq; 1098 #endif /* IW_MODE_MONITOR */ 1099 1100 if (handle->md.must_do_on_close != 0) { 1101 /* 1102 * There's something we have to do when closing this 1103 * pcap_t. 1104 */ 1105 if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) { 1106 /* 1107 * We put the interface into promiscuous mode; 1108 * take it out of promiscuous mode. 1109 * 1110 * XXX - if somebody else wants it in promiscuous 1111 * mode, this code cannot know that, so it'll take 1112 * it out of promiscuous mode. That's not fixable 1113 * in 2.0[.x] kernels. 1114 */ 1115 memset(&ifr, 0, sizeof(ifr)); 1116 strncpy(ifr.ifr_name, handle->md.device, 1117 sizeof(ifr.ifr_name)); 1118 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { 1119 fprintf(stderr, 1120 "Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n" 1121 "Please adjust manually.\n" 1122 "Hint: This can't happen with Linux >= 2.2.0.\n", 1123 handle->md.device, strerror(errno)); 1124 } else { 1125 if (ifr.ifr_flags & IFF_PROMISC) { 1126 /* 1127 * Promiscuous mode is currently on; 1128 * turn it off. 1129 */ 1130 ifr.ifr_flags &= ~IFF_PROMISC; 1131 if (ioctl(handle->fd, SIOCSIFFLAGS, 1132 &ifr) == -1) { 1133 fprintf(stderr, 1134 "Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n" 1135 "Please adjust manually.\n" 1136 "Hint: This can't happen with Linux >= 2.2.0.\n", 1137 handle->md.device, 1138 strerror(errno)); 1139 } 1140 } 1141 } 1142 } 1143 1144 #ifdef HAVE_LIBNL 1145 if (handle->md.must_do_on_close & MUST_DELETE_MONIF) { 1146 ret = nl80211_init(handle, &nlstate, handle->md.device); 1147 if (ret >= 0) { 1148 ret = del_mon_if(handle, handle->fd, &nlstate, 1149 handle->md.device, handle->md.mondevice); 1150 nl80211_cleanup(&nlstate); 1151 } 1152 if (ret < 0) { 1153 fprintf(stderr, 1154 "Can't delete monitor interface %s (%s).\n" 1155 "Please delete manually.\n", 1156 handle->md.mondevice, handle->errbuf); 1157 } 1158 } 1159 #endif /* HAVE_LIBNL */ 1160 1161 #ifdef IW_MODE_MONITOR 1162 if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) { 1163 /* 1164 * We put the interface into rfmon mode; 1165 * take it out of rfmon mode. 1166 * 1167 * XXX - if somebody else wants it in rfmon 1168 * mode, this code cannot know that, so it'll take 1169 * it out of rfmon mode. 1170 */ 1171 1172 /* 1173 * First, take the interface down if it's up; 1174 * otherwise, we might get EBUSY. 1175 * If we get errors, just drive on and print 1176 * a warning if we can't restore the mode. 1177 */ 1178 oldflags = 0; 1179 memset(&ifr, 0, sizeof(ifr)); 1180 strncpy(ifr.ifr_name, handle->md.device, 1181 sizeof(ifr.ifr_name)); 1182 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) { 1183 if (ifr.ifr_flags & IFF_UP) { 1184 oldflags = ifr.ifr_flags; 1185 ifr.ifr_flags &= ~IFF_UP; 1186 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) 1187 oldflags = 0; /* didn't set, don't restore */ 1188 } 1189 } 1190 1191 /* 1192 * Now restore the mode. 1193 */ 1194 strncpy(ireq.ifr_ifrn.ifrn_name, handle->md.device, 1195 sizeof ireq.ifr_ifrn.ifrn_name); 1196 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] 1197 = 0; 1198 ireq.u.mode = handle->md.oldmode; 1199 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { 1200 /* 1201 * Scientist, you've failed. 1202 */ 1203 fprintf(stderr, 1204 "Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n" 1205 "Please adjust manually.\n", 1206 handle->md.device, strerror(errno)); 1207 } 1208 1209 /* 1210 * Now bring the interface back up if we brought 1211 * it down. 1212 */ 1213 if (oldflags != 0) { 1214 ifr.ifr_flags = oldflags; 1215 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { 1216 fprintf(stderr, 1217 "Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n" 1218 "Please adjust manually.\n", 1219 handle->md.device, strerror(errno)); 1220 } 1221 } 1222 } 1223 #endif /* IW_MODE_MONITOR */ 1224 1225 /* 1226 * Take this pcap out of the list of pcaps for which we 1227 * have to take the interface out of some mode. 1228 */ 1229 pcap_remove_from_pcaps_to_close(handle); 1230 } 1231 1232 if (handle->md.mondevice != NULL) { 1233 free(handle->md.mondevice); 1234 handle->md.mondevice = NULL; 1235 } 1236 if (handle->md.device != NULL) { 1237 free(handle->md.device); 1238 handle->md.device = NULL; 1239 } 1240 pcap_cleanup_live_common(handle); 1241 } 1242 1243 /* 1244 * Get a handle for a live capture from the given device. You can 1245 * pass NULL as device to get all packages (without link level 1246 * information of course). If you pass 1 as promisc the interface 1247 * will be set to promiscous mode (XXX: I think this usage should 1248 * be deprecated and functions be added to select that later allow 1249 * modification of that values -- Torsten). 1250 */ 1251 static int 1252 pcap_activate_linux(pcap_t *handle) 1253 { 1254 const char *device; 1255 int status = 0; 1256 1257 device = handle->opt.source; 1258 1259 handle->inject_op = pcap_inject_linux; 1260 handle->setfilter_op = pcap_setfilter_linux; 1261 handle->setdirection_op = pcap_setdirection_linux; 1262 handle->set_datalink_op = NULL; /* can't change data link type */ 1263 handle->getnonblock_op = pcap_getnonblock_fd; 1264 handle->setnonblock_op = pcap_setnonblock_fd; 1265 handle->cleanup_op = pcap_cleanup_linux; 1266 handle->read_op = pcap_read_linux; 1267 handle->stats_op = pcap_stats_linux; 1268 1269 /* 1270 * The "any" device is a special device which causes us not 1271 * to bind to a particular device and thus to look at all 1272 * devices. 1273 */ 1274 if (strcmp(device, "any") == 0) { 1275 if (handle->opt.promisc) { 1276 handle->opt.promisc = 0; 1277 /* Just a warning. */ 1278 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1279 "Promiscuous mode not supported on the \"any\" device"); 1280 status = PCAP_WARNING_PROMISC_NOTSUP; 1281 } 1282 } 1283 1284 handle->md.device = strdup(device); 1285 if (handle->md.device == NULL) { 1286 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s", 1287 pcap_strerror(errno) ); 1288 return PCAP_ERROR; 1289 } 1290 1291 /* 1292 * If we're in promiscuous mode, then we probably want 1293 * to see when the interface drops packets too, so get an 1294 * initial count from /proc/net/dev 1295 */ 1296 if (handle->opt.promisc) 1297 handle->md.proc_dropped = linux_if_drops(handle->md.device); 1298 1299 /* 1300 * Current Linux kernels use the protocol family PF_PACKET to 1301 * allow direct access to all packets on the network while 1302 * older kernels had a special socket type SOCK_PACKET to 1303 * implement this feature. 1304 * While this old implementation is kind of obsolete we need 1305 * to be compatible with older kernels for a while so we are 1306 * trying both methods with the newer method preferred. 1307 */ 1308 status = activate_new(handle); 1309 if (status < 0) { 1310 /* 1311 * Fatal error with the new way; just fail. 1312 * status has the error return; if it's PCAP_ERROR, 1313 * handle->errbuf has been set appropriately. 1314 */ 1315 goto fail; 1316 } 1317 if (status == 1) { 1318 /* 1319 * Success. 1320 * Try to use memory-mapped access. 1321 */ 1322 switch (activate_mmap(handle, &status)) { 1323 1324 case 1: 1325 /* 1326 * We succeeded. status has been 1327 * set to the status to return, 1328 * which might be 0, or might be 1329 * a PCAP_WARNING_ value. 1330 */ 1331 return status; 1332 1333 case 0: 1334 /* 1335 * Kernel doesn't support it - just continue 1336 * with non-memory-mapped access. 1337 */ 1338 break; 1339 1340 case -1: 1341 /* 1342 * We failed to set up to use it, or the kernel 1343 * supports it, but we failed to enable it. 1344 * status has been set to the error status to 1345 * return and, if it's PCAP_ERROR, handle->errbuf 1346 * contains the error message. 1347 */ 1348 goto fail; 1349 } 1350 } 1351 else if (status == 0) { 1352 /* Non-fatal error; try old way */ 1353 if ((status = activate_old(handle)) != 1) { 1354 /* 1355 * Both methods to open the packet socket failed. 1356 * Tidy up and report our failure (handle->errbuf 1357 * is expected to be set by the functions above). 1358 */ 1359 goto fail; 1360 } 1361 } 1362 1363 /* 1364 * We set up the socket, but not with memory-mapped access. 1365 */ 1366 status = 0; 1367 if (handle->opt.buffer_size != 0) { 1368 /* 1369 * Set the socket buffer size to the specified value. 1370 */ 1371 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, 1372 &handle->opt.buffer_size, 1373 sizeof(handle->opt.buffer_size)) == -1) { 1374 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1375 "SO_RCVBUF: %s", pcap_strerror(errno)); 1376 status = PCAP_ERROR; 1377 goto fail; 1378 } 1379 } 1380 1381 /* Allocate the buffer */ 1382 1383 handle->buffer = malloc(handle->bufsize + handle->offset); 1384 if (!handle->buffer) { 1385 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1386 "malloc: %s", pcap_strerror(errno)); 1387 status = PCAP_ERROR; 1388 goto fail; 1389 } 1390 1391 /* 1392 * "handle->fd" is a socket, so "select()" and "poll()" 1393 * should work on it. 1394 */ 1395 handle->selectable_fd = handle->fd; 1396 1397 return status; 1398 1399 fail: 1400 pcap_cleanup_linux(handle); 1401 return status; 1402 } 1403 1404 /* 1405 * Read at most max_packets from the capture stream and call the callback 1406 * for each of them. Returns the number of packets handled or -1 if an 1407 * error occured. 1408 */ 1409 static int 1410 pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) 1411 { 1412 /* 1413 * Currently, on Linux only one packet is delivered per read, 1414 * so we don't loop. 1415 */ 1416 return pcap_read_packet(handle, callback, user); 1417 } 1418 1419 /* 1420 * Read a packet from the socket calling the handler provided by 1421 * the user. Returns the number of packets received or -1 if an 1422 * error occured. 1423 */ 1424 static int 1425 pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata) 1426 { 1427 u_char *bp; 1428 int offset; 1429 #ifdef HAVE_PF_PACKET_SOCKETS 1430 struct sockaddr_ll from; 1431 struct sll_header *hdrp; 1432 #else 1433 struct sockaddr from; 1434 #endif 1435 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1436 struct iovec iov; 1437 struct msghdr msg; 1438 struct cmsghdr *cmsg; 1439 union { 1440 struct cmsghdr cmsg; 1441 char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))]; 1442 } cmsg_buf; 1443 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1444 socklen_t fromlen; 1445 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1446 int packet_len, caplen; 1447 struct pcap_pkthdr pcap_header; 1448 1449 #ifdef HAVE_PF_PACKET_SOCKETS 1450 /* 1451 * If this is a cooked device, leave extra room for a 1452 * fake packet header. 1453 */ 1454 if (handle->md.cooked) 1455 offset = SLL_HDR_LEN; 1456 else 1457 offset = 0; 1458 #else 1459 /* 1460 * This system doesn't have PF_PACKET sockets, so it doesn't 1461 * support cooked devices. 1462 */ 1463 offset = 0; 1464 #endif 1465 1466 /* 1467 * Receive a single packet from the kernel. 1468 * We ignore EINTR, as that might just be due to a signal 1469 * being delivered - if the signal should interrupt the 1470 * loop, the signal handler should call pcap_breakloop() 1471 * to set handle->break_loop (we ignore it on other 1472 * platforms as well). 1473 * We also ignore ENETDOWN, so that we can continue to 1474 * capture traffic if the interface goes down and comes 1475 * back up again; comments in the kernel indicate that 1476 * we'll just block waiting for packets if we try to 1477 * receive from a socket that delivered ENETDOWN, and, 1478 * if we're using a memory-mapped buffer, we won't even 1479 * get notified of "network down" events. 1480 */ 1481 bp = handle->buffer + handle->offset; 1482 1483 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1484 msg.msg_name = &from; 1485 msg.msg_namelen = sizeof(from); 1486 msg.msg_iov = &iov; 1487 msg.msg_iovlen = 1; 1488 msg.msg_control = &cmsg_buf; 1489 msg.msg_controllen = sizeof(cmsg_buf); 1490 msg.msg_flags = 0; 1491 1492 iov.iov_len = handle->bufsize - offset; 1493 iov.iov_base = bp + offset; 1494 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1495 1496 do { 1497 /* 1498 * Has "pcap_breakloop()" been called? 1499 */ 1500 if (handle->break_loop) { 1501 /* 1502 * Yes - clear the flag that indicates that it has, 1503 * and return PCAP_ERROR_BREAK as an indication that 1504 * we were told to break out of the loop. 1505 */ 1506 handle->break_loop = 0; 1507 return PCAP_ERROR_BREAK; 1508 } 1509 1510 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1511 packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC); 1512 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1513 fromlen = sizeof(from); 1514 packet_len = recvfrom( 1515 handle->fd, bp + offset, 1516 handle->bufsize - offset, MSG_TRUNC, 1517 (struct sockaddr *) &from, &fromlen); 1518 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1519 } while (packet_len == -1 && errno == EINTR); 1520 1521 /* Check if an error occured */ 1522 1523 if (packet_len == -1) { 1524 switch (errno) { 1525 1526 case EAGAIN: 1527 return 0; /* no packet there */ 1528 1529 case ENETDOWN: 1530 /* 1531 * The device on which we're capturing went away. 1532 * 1533 * XXX - we should really return 1534 * PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch() 1535 * etc. aren't defined to return that. 1536 */ 1537 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1538 "The interface went down"); 1539 return PCAP_ERROR; 1540 1541 default: 1542 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1543 "recvfrom: %s", pcap_strerror(errno)); 1544 return PCAP_ERROR; 1545 } 1546 } 1547 1548 #ifdef HAVE_PF_PACKET_SOCKETS 1549 if (!handle->md.sock_packet) { 1550 /* 1551 * Unfortunately, there is a window between socket() and 1552 * bind() where the kernel may queue packets from any 1553 * interface. If we're bound to a particular interface, 1554 * discard packets not from that interface. 1555 * 1556 * (If socket filters are supported, we could do the 1557 * same thing we do when changing the filter; however, 1558 * that won't handle packet sockets without socket 1559 * filter support, and it's a bit more complicated. 1560 * It would save some instructions per packet, however.) 1561 */ 1562 if (handle->md.ifindex != -1 && 1563 from.sll_ifindex != handle->md.ifindex) 1564 return 0; 1565 1566 /* 1567 * Do checks based on packet direction. 1568 * We can only do this if we're using PF_PACKET; the 1569 * address returned for SOCK_PACKET is a "sockaddr_pkt" 1570 * which lacks the relevant packet type information. 1571 */ 1572 if (from.sll_pkttype == PACKET_OUTGOING) { 1573 /* 1574 * Outgoing packet. 1575 * If this is from the loopback device, reject it; 1576 * we'll see the packet as an incoming packet as well, 1577 * and we don't want to see it twice. 1578 */ 1579 if (from.sll_ifindex == handle->md.lo_ifindex) 1580 return 0; 1581 1582 /* 1583 * If the user only wants incoming packets, reject it. 1584 */ 1585 if (handle->direction == PCAP_D_IN) 1586 return 0; 1587 } else { 1588 /* 1589 * Incoming packet. 1590 * If the user only wants outgoing packets, reject it. 1591 */ 1592 if (handle->direction == PCAP_D_OUT) 1593 return 0; 1594 } 1595 } 1596 #endif 1597 1598 #ifdef HAVE_PF_PACKET_SOCKETS 1599 /* 1600 * If this is a cooked device, fill in the fake packet header. 1601 */ 1602 if (handle->md.cooked) { 1603 /* 1604 * Add the length of the fake header to the length 1605 * of packet data we read. 1606 */ 1607 packet_len += SLL_HDR_LEN; 1608 1609 hdrp = (struct sll_header *)bp; 1610 hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype); 1611 hdrp->sll_hatype = htons(from.sll_hatype); 1612 hdrp->sll_halen = htons(from.sll_halen); 1613 memcpy(hdrp->sll_addr, from.sll_addr, 1614 (from.sll_halen > SLL_ADDRLEN) ? 1615 SLL_ADDRLEN : 1616 from.sll_halen); 1617 hdrp->sll_protocol = from.sll_protocol; 1618 } 1619 1620 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) 1621 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { 1622 struct tpacket_auxdata *aux; 1623 unsigned int len; 1624 struct vlan_tag *tag; 1625 1626 if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) || 1627 cmsg->cmsg_level != SOL_PACKET || 1628 cmsg->cmsg_type != PACKET_AUXDATA) 1629 continue; 1630 1631 aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg); 1632 if (aux->tp_vlan_tci == 0) 1633 continue; 1634 1635 len = packet_len > iov.iov_len ? iov.iov_len : packet_len; 1636 if (len < 2 * ETH_ALEN) 1637 break; 1638 1639 bp -= VLAN_TAG_LEN; 1640 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); 1641 1642 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); 1643 tag->vlan_tpid = htons(ETH_P_8021Q); 1644 tag->vlan_tci = htons(aux->tp_vlan_tci); 1645 1646 packet_len += VLAN_TAG_LEN; 1647 } 1648 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ 1649 #endif /* HAVE_PF_PACKET_SOCKETS */ 1650 1651 /* 1652 * XXX: According to the kernel source we should get the real 1653 * packet len if calling recvfrom with MSG_TRUNC set. It does 1654 * not seem to work here :(, but it is supported by this code 1655 * anyway. 1656 * To be honest the code RELIES on that feature so this is really 1657 * broken with 2.2.x kernels. 1658 * I spend a day to figure out what's going on and I found out 1659 * that the following is happening: 1660 * 1661 * The packet comes from a random interface and the packet_rcv 1662 * hook is called with a clone of the packet. That code inserts 1663 * the packet into the receive queue of the packet socket. 1664 * If a filter is attached to that socket that filter is run 1665 * first - and there lies the problem. The default filter always 1666 * cuts the packet at the snaplen: 1667 * 1668 * # tcpdump -d 1669 * (000) ret #68 1670 * 1671 * So the packet filter cuts down the packet. The recvfrom call 1672 * says "hey, it's only 68 bytes, it fits into the buffer" with 1673 * the result that we don't get the real packet length. This 1674 * is valid at least until kernel 2.2.17pre6. 1675 * 1676 * We currently handle this by making a copy of the filter 1677 * program, fixing all "ret" instructions with non-zero 1678 * operands to have an operand of 65535 so that the filter 1679 * doesn't truncate the packet, and supplying that modified 1680 * filter to the kernel. 1681 */ 1682 1683 caplen = packet_len; 1684 if (caplen > handle->snapshot) 1685 caplen = handle->snapshot; 1686 1687 /* Run the packet filter if not using kernel filter */ 1688 if (!handle->md.use_bpf && handle->fcode.bf_insns) { 1689 if (bpf_filter(handle->fcode.bf_insns, bp, 1690 packet_len, caplen) == 0) 1691 { 1692 /* rejected by filter */ 1693 return 0; 1694 } 1695 } 1696 1697 /* Fill in our own header data */ 1698 1699 if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) { 1700 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1701 "SIOCGSTAMP: %s", pcap_strerror(errno)); 1702 return PCAP_ERROR; 1703 } 1704 pcap_header.caplen = caplen; 1705 pcap_header.len = packet_len; 1706 1707 /* 1708 * Count the packet. 1709 * 1710 * Arguably, we should count them before we check the filter, 1711 * as on many other platforms "ps_recv" counts packets 1712 * handed to the filter rather than packets that passed 1713 * the filter, but if filtering is done in the kernel, we 1714 * can't get a count of packets that passed the filter, 1715 * and that would mean the meaning of "ps_recv" wouldn't 1716 * be the same on all Linux systems. 1717 * 1718 * XXX - it's not the same on all systems in any case; 1719 * ideally, we should have a "get the statistics" call 1720 * that supplies more counts and indicates which of them 1721 * it supplies, so that we supply a count of packets 1722 * handed to the filter only on platforms where that 1723 * information is available. 1724 * 1725 * We count them here even if we can get the packet count 1726 * from the kernel, as we can only determine at run time 1727 * whether we'll be able to get it from the kernel (if 1728 * HAVE_TPACKET_STATS isn't defined, we can't get it from 1729 * the kernel, but if it is defined, the library might 1730 * have been built with a 2.4 or later kernel, but we 1731 * might be running on a 2.2[.x] kernel without Alexey 1732 * Kuznetzov's turbopacket patches, and thus the kernel 1733 * might not be able to supply those statistics). We 1734 * could, I guess, try, when opening the socket, to get 1735 * the statistics, and if we can not increment the count 1736 * here, but it's not clear that always incrementing 1737 * the count is more expensive than always testing a flag 1738 * in memory. 1739 * 1740 * We keep the count in "md.packets_read", and use that for 1741 * "ps_recv" if we can't get the statistics from the kernel. 1742 * We do that because, if we *can* get the statistics from 1743 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop" 1744 * as running counts, as reading the statistics from the 1745 * kernel resets the kernel statistics, and if we directly 1746 * increment "md.stat.ps_recv" here, that means it will 1747 * count packets *twice* on systems where we can get kernel 1748 * statistics - once here, and once in pcap_stats_linux(). 1749 */ 1750 handle->md.packets_read++; 1751 1752 /* Call the user supplied callback function */ 1753 callback(userdata, &pcap_header, bp); 1754 1755 return 1; 1756 } 1757 1758 static int 1759 pcap_inject_linux(pcap_t *handle, const void *buf, size_t size) 1760 { 1761 int ret; 1762 1763 #ifdef HAVE_PF_PACKET_SOCKETS 1764 if (!handle->md.sock_packet) { 1765 /* PF_PACKET socket */ 1766 if (handle->md.ifindex == -1) { 1767 /* 1768 * We don't support sending on the "any" device. 1769 */ 1770 strlcpy(handle->errbuf, 1771 "Sending packets isn't supported on the \"any\" device", 1772 PCAP_ERRBUF_SIZE); 1773 return (-1); 1774 } 1775 1776 if (handle->md.cooked) { 1777 /* 1778 * We don't support sending on the "any" device. 1779 * 1780 * XXX - how do you send on a bound cooked-mode 1781 * socket? 1782 * Is a "sendto()" required there? 1783 */ 1784 strlcpy(handle->errbuf, 1785 "Sending packets isn't supported in cooked mode", 1786 PCAP_ERRBUF_SIZE); 1787 return (-1); 1788 } 1789 } 1790 #endif 1791 1792 ret = send(handle->fd, buf, size, 0); 1793 if (ret == -1) { 1794 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s", 1795 pcap_strerror(errno)); 1796 return (-1); 1797 } 1798 return (ret); 1799 } 1800 1801 /* 1802 * Get the statistics for the given packet capture handle. 1803 * Reports the number of dropped packets iff the kernel supports 1804 * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later 1805 * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket 1806 * patches); otherwise, that information isn't available, and we lie 1807 * and report 0 as the count of dropped packets. 1808 */ 1809 static int 1810 pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) 1811 { 1812 #ifdef HAVE_TPACKET_STATS 1813 struct tpacket_stats kstats; 1814 socklen_t len = sizeof (struct tpacket_stats); 1815 #endif 1816 1817 long if_dropped = 0; 1818 1819 /* 1820 * To fill in ps_ifdrop, we parse /proc/net/dev for the number 1821 */ 1822 if (handle->opt.promisc) 1823 { 1824 if_dropped = handle->md.proc_dropped; 1825 handle->md.proc_dropped = linux_if_drops(handle->md.device); 1826 handle->md.stat.ps_ifdrop += (handle->md.proc_dropped - if_dropped); 1827 } 1828 1829 #ifdef HAVE_TPACKET_STATS 1830 /* 1831 * Try to get the packet counts from the kernel. 1832 */ 1833 if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, 1834 &kstats, &len) > -1) { 1835 /* 1836 * On systems where the PACKET_STATISTICS "getsockopt()" 1837 * argument is supported on PF_PACKET sockets: 1838 * 1839 * "ps_recv" counts only packets that *passed* the 1840 * filter, not packets that didn't pass the filter. 1841 * This includes packets later dropped because we 1842 * ran out of buffer space. 1843 * 1844 * "ps_drop" counts packets dropped because we ran 1845 * out of buffer space. It doesn't count packets 1846 * dropped by the interface driver. It counts only 1847 * packets that passed the filter. 1848 * 1849 * See above for ps_ifdrop. 1850 * 1851 * Both statistics include packets not yet read from 1852 * the kernel by libpcap, and thus not yet seen by 1853 * the application. 1854 * 1855 * In "linux/net/packet/af_packet.c", at least in the 1856 * 2.4.9 kernel, "tp_packets" is incremented for every 1857 * packet that passes the packet filter *and* is 1858 * successfully queued on the socket; "tp_drops" is 1859 * incremented for every packet dropped because there's 1860 * not enough free space in the socket buffer. 1861 * 1862 * When the statistics are returned for a PACKET_STATISTICS 1863 * "getsockopt()" call, "tp_drops" is added to "tp_packets", 1864 * so that "tp_packets" counts all packets handed to 1865 * the PF_PACKET socket, including packets dropped because 1866 * there wasn't room on the socket buffer - but not 1867 * including packets that didn't pass the filter. 1868 * 1869 * In the BSD BPF, the count of received packets is 1870 * incremented for every packet handed to BPF, regardless 1871 * of whether it passed the filter. 1872 * 1873 * We can't make "pcap_stats()" work the same on both 1874 * platforms, but the best approximation is to return 1875 * "tp_packets" as the count of packets and "tp_drops" 1876 * as the count of drops. 1877 * 1878 * Keep a running total because each call to 1879 * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, .... 1880 * resets the counters to zero. 1881 */ 1882 handle->md.stat.ps_recv += kstats.tp_packets; 1883 handle->md.stat.ps_drop += kstats.tp_drops; 1884 *stats = handle->md.stat; 1885 return 0; 1886 } 1887 else 1888 { 1889 /* 1890 * If the error was EOPNOTSUPP, fall through, so that 1891 * if you build the library on a system with 1892 * "struct tpacket_stats" and run it on a system 1893 * that doesn't, it works as it does if the library 1894 * is built on a system without "struct tpacket_stats". 1895 */ 1896 if (errno != EOPNOTSUPP) { 1897 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 1898 "pcap_stats: %s", pcap_strerror(errno)); 1899 return -1; 1900 } 1901 } 1902 #endif 1903 /* 1904 * On systems where the PACKET_STATISTICS "getsockopt()" argument 1905 * is not supported on PF_PACKET sockets: 1906 * 1907 * "ps_recv" counts only packets that *passed* the filter, 1908 * not packets that didn't pass the filter. It does not 1909 * count packets dropped because we ran out of buffer 1910 * space. 1911 * 1912 * "ps_drop" is not supported. 1913 * 1914 * "ps_ifdrop" is supported. It will return the number 1915 * of drops the interface reports in /proc/net/dev, 1916 * if that is available. 1917 * 1918 * "ps_recv" doesn't include packets not yet read from 1919 * the kernel by libpcap. 1920 * 1921 * We maintain the count of packets processed by libpcap in 1922 * "md.packets_read", for reasons described in the comment 1923 * at the end of pcap_read_packet(). We have no idea how many 1924 * packets were dropped by the kernel buffers -- but we know 1925 * how many the interface dropped, so we can return that. 1926 */ 1927 1928 stats->ps_recv = handle->md.packets_read; 1929 stats->ps_drop = 0; 1930 stats->ps_ifdrop = handle->md.stat.ps_ifdrop; 1931 return 0; 1932 } 1933 1934 /* 1935 * Get from "/sys/class/net" all interfaces listed there; if they're 1936 * already in the list of interfaces we have, that won't add another 1937 * instance, but if they're not, that'll add them. 1938 * 1939 * We don't bother getting any addresses for them; it appears you can't 1940 * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and, 1941 * although some other types of addresses can be fetched with SIOCGIFADDR, 1942 * we don't bother with them for now. 1943 * 1944 * We also don't fail if we couldn't open "/sys/class/net"; we just leave 1945 * the list of interfaces as is, and return 0, so that we can try 1946 * scanning /proc/net/dev. 1947 */ 1948 static int 1949 scan_sys_class_net(pcap_if_t **devlistp, char *errbuf) 1950 { 1951 DIR *sys_class_net_d; 1952 int fd; 1953 struct dirent *ent; 1954 char *p; 1955 char name[512]; /* XXX - pick a size */ 1956 char *q, *saveq; 1957 struct ifreq ifrflags; 1958 int ret = 1; 1959 1960 sys_class_net_d = opendir("/sys/class/net"); 1961 if (sys_class_net_d == NULL) { 1962 /* 1963 * Don't fail if it doesn't exist at all. 1964 */ 1965 if (errno == ENOENT) 1966 return (0); 1967 1968 /* 1969 * Fail if we got some other error. 1970 */ 1971 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 1972 "Can't open /sys/class/net: %s", pcap_strerror(errno)); 1973 return (-1); 1974 } 1975 1976 /* 1977 * Create a socket from which to fetch interface information. 1978 */ 1979 fd = socket(AF_INET, SOCK_DGRAM, 0); 1980 if (fd < 0) { 1981 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 1982 "socket: %s", pcap_strerror(errno)); 1983 (void)closedir(sys_class_net_d); 1984 return (-1); 1985 } 1986 1987 for (;;) { 1988 errno = 0; 1989 ent = readdir(sys_class_net_d); 1990 if (ent == NULL) { 1991 /* 1992 * Error or EOF; if errno != 0, it's an error. 1993 */ 1994 break; 1995 } 1996 1997 /* 1998 * Ignore directories (".", "..", and any subdirectories). 1999 */ 2000 if (ent->d_type == DT_DIR) 2001 continue; 2002 2003 /* 2004 * Get the interface name. 2005 */ 2006 p = &ent->d_name[0]; 2007 q = &name[0]; 2008 while (*p != '\0' && isascii(*p) && !isspace(*p)) { 2009 if (*p == ':') { 2010 /* 2011 * This could be the separator between a 2012 * name and an alias number, or it could be 2013 * the separator between a name with no 2014 * alias number and the next field. 2015 * 2016 * If there's a colon after digits, it 2017 * separates the name and the alias number, 2018 * otherwise it separates the name and the 2019 * next field. 2020 */ 2021 saveq = q; 2022 while (isascii(*p) && isdigit(*p)) 2023 *q++ = *p++; 2024 if (*p != ':') { 2025 /* 2026 * That was the next field, 2027 * not the alias number. 2028 */ 2029 q = saveq; 2030 } 2031 break; 2032 } else 2033 *q++ = *p++; 2034 } 2035 *q = '\0'; 2036 2037 /* 2038 * Get the flags for this interface, and skip it if 2039 * it's not up. 2040 */ 2041 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); 2042 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { 2043 if (errno == ENXIO || errno == ENODEV) 2044 continue; 2045 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2046 "SIOCGIFFLAGS: %.*s: %s", 2047 (int)sizeof(ifrflags.ifr_name), 2048 ifrflags.ifr_name, 2049 pcap_strerror(errno)); 2050 ret = -1; 2051 break; 2052 } 2053 if (!(ifrflags.ifr_flags & IFF_UP)) 2054 continue; 2055 2056 /* 2057 * Add an entry for this interface, with no addresses. 2058 */ 2059 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL, 2060 errbuf) == -1) { 2061 /* 2062 * Failure. 2063 */ 2064 ret = -1; 2065 break; 2066 } 2067 } 2068 if (ret != -1) { 2069 /* 2070 * Well, we didn't fail for any other reason; did we 2071 * fail due to an error reading the directory? 2072 */ 2073 if (errno != 0) { 2074 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2075 "Error reading /sys/class/net: %s", 2076 pcap_strerror(errno)); 2077 ret = -1; 2078 } 2079 } 2080 2081 (void)close(fd); 2082 (void)closedir(sys_class_net_d); 2083 return (ret); 2084 } 2085 2086 /* 2087 * Get from "/proc/net/dev" all interfaces listed there; if they're 2088 * already in the list of interfaces we have, that won't add another 2089 * instance, but if they're not, that'll add them. 2090 * 2091 * See comments from scan_sys_class_net(). 2092 */ 2093 static int 2094 scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf) 2095 { 2096 FILE *proc_net_f; 2097 int fd; 2098 char linebuf[512]; 2099 int linenum; 2100 char *p; 2101 char name[512]; /* XXX - pick a size */ 2102 char *q, *saveq; 2103 struct ifreq ifrflags; 2104 int ret = 0; 2105 2106 proc_net_f = fopen("/proc/net/dev", "r"); 2107 if (proc_net_f == NULL) { 2108 /* 2109 * Don't fail if it doesn't exist at all. 2110 */ 2111 if (errno == ENOENT) 2112 return (0); 2113 2114 /* 2115 * Fail if we got some other error. 2116 */ 2117 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2118 "Can't open /proc/net/dev: %s", pcap_strerror(errno)); 2119 return (-1); 2120 } 2121 2122 /* 2123 * Create a socket from which to fetch interface information. 2124 */ 2125 fd = socket(AF_INET, SOCK_DGRAM, 0); 2126 if (fd < 0) { 2127 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2128 "socket: %s", pcap_strerror(errno)); 2129 (void)fclose(proc_net_f); 2130 return (-1); 2131 } 2132 2133 for (linenum = 1; 2134 fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) { 2135 /* 2136 * Skip the first two lines - they're headers. 2137 */ 2138 if (linenum <= 2) 2139 continue; 2140 2141 p = &linebuf[0]; 2142 2143 /* 2144 * Skip leading white space. 2145 */ 2146 while (*p != '\0' && isascii(*p) && isspace(*p)) 2147 p++; 2148 if (*p == '\0' || *p == '\n') 2149 continue; /* blank line */ 2150 2151 /* 2152 * Get the interface name. 2153 */ 2154 q = &name[0]; 2155 while (*p != '\0' && isascii(*p) && !isspace(*p)) { 2156 if (*p == ':') { 2157 /* 2158 * This could be the separator between a 2159 * name and an alias number, or it could be 2160 * the separator between a name with no 2161 * alias number and the next field. 2162 * 2163 * If there's a colon after digits, it 2164 * separates the name and the alias number, 2165 * otherwise it separates the name and the 2166 * next field. 2167 */ 2168 saveq = q; 2169 while (isascii(*p) && isdigit(*p)) 2170 *q++ = *p++; 2171 if (*p != ':') { 2172 /* 2173 * That was the next field, 2174 * not the alias number. 2175 */ 2176 q = saveq; 2177 } 2178 break; 2179 } else 2180 *q++ = *p++; 2181 } 2182 *q = '\0'; 2183 2184 /* 2185 * Get the flags for this interface, and skip it if 2186 * it's not up. 2187 */ 2188 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); 2189 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { 2190 if (errno == ENXIO) 2191 continue; 2192 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2193 "SIOCGIFFLAGS: %.*s: %s", 2194 (int)sizeof(ifrflags.ifr_name), 2195 ifrflags.ifr_name, 2196 pcap_strerror(errno)); 2197 ret = -1; 2198 break; 2199 } 2200 if (!(ifrflags.ifr_flags & IFF_UP)) 2201 continue; 2202 2203 /* 2204 * Add an entry for this interface, with no addresses. 2205 */ 2206 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL, 2207 errbuf) == -1) { 2208 /* 2209 * Failure. 2210 */ 2211 ret = -1; 2212 break; 2213 } 2214 } 2215 if (ret != -1) { 2216 /* 2217 * Well, we didn't fail for any other reason; did we 2218 * fail due to an error reading the file? 2219 */ 2220 if (ferror(proc_net_f)) { 2221 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 2222 "Error reading /proc/net/dev: %s", 2223 pcap_strerror(errno)); 2224 ret = -1; 2225 } 2226 } 2227 2228 (void)close(fd); 2229 (void)fclose(proc_net_f); 2230 return (ret); 2231 } 2232 2233 /* 2234 * Description string for the "any" device. 2235 */ 2236 static const char any_descr[] = "Pseudo-device that captures on all interfaces"; 2237 2238 int 2239 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) 2240 { 2241 int ret; 2242 2243 /* 2244 * Read "/sys/class/net", and add to the list of interfaces all 2245 * interfaces listed there that we don't already have, because, 2246 * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses, 2247 * and even getifaddrs() won't return information about 2248 * interfaces with no addresses, so you need to read "/sys/class/net" 2249 * to get the names of the rest of the interfaces. 2250 */ 2251 ret = scan_sys_class_net(alldevsp, errbuf); 2252 if (ret == -1) 2253 return (-1); /* failed */ 2254 if (ret == 0) { 2255 /* 2256 * No /sys/class/net; try reading /proc/net/dev instead. 2257 */ 2258 if (scan_proc_net_dev(alldevsp, errbuf) == -1) 2259 return (-1); 2260 } 2261 2262 /* 2263 * Add the "any" device. 2264 */ 2265 if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0) 2266 return (-1); 2267 2268 #ifdef HAVE_DAG_API 2269 /* 2270 * Add DAG devices. 2271 */ 2272 if (dag_platform_finddevs(alldevsp, errbuf) < 0) 2273 return (-1); 2274 #endif /* HAVE_DAG_API */ 2275 2276 #ifdef HAVE_SEPTEL_API 2277 /* 2278 * Add Septel devices. 2279 */ 2280 if (septel_platform_finddevs(alldevsp, errbuf) < 0) 2281 return (-1); 2282 #endif /* HAVE_SEPTEL_API */ 2283 2284 #ifdef HAVE_SNF_API 2285 if (snf_platform_finddevs(alldevsp, errbuf) < 0) 2286 return (-1); 2287 #endif /* HAVE_SNF_API */ 2288 2289 #ifdef PCAP_SUPPORT_BT 2290 /* 2291 * Add Bluetooth devices. 2292 */ 2293 if (bt_platform_finddevs(alldevsp, errbuf) < 0) 2294 return (-1); 2295 #endif 2296 2297 #ifdef PCAP_SUPPORT_USB 2298 /* 2299 * Add USB devices. 2300 */ 2301 if (usb_platform_finddevs(alldevsp, errbuf) < 0) 2302 return (-1); 2303 #endif 2304 2305 #ifdef PCAP_SUPPORT_NETFILTER 2306 /* 2307 * Add netfilter devices. 2308 */ 2309 if (netfilter_platform_finddevs(alldevsp, errbuf) < 0) 2310 return (-1); 2311 #endif 2312 2313 #if PCAP_SUPPORT_CANUSB 2314 if (canusb_platform_finddevs(alldevsp, errbuf) < 0) 2315 return (-1); 2316 #endif 2317 2318 return (0); 2319 } 2320 2321 /* 2322 * Attach the given BPF code to the packet capture device. 2323 */ 2324 static int 2325 pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, 2326 int is_mmapped) 2327 { 2328 #ifdef SO_ATTACH_FILTER 2329 struct sock_fprog fcode; 2330 int can_filter_in_kernel; 2331 int err = 0; 2332 #endif 2333 2334 if (!handle) 2335 return -1; 2336 if (!filter) { 2337 strncpy(handle->errbuf, "setfilter: No filter specified", 2338 PCAP_ERRBUF_SIZE); 2339 return -1; 2340 } 2341 2342 /* Make our private copy of the filter */ 2343 2344 if (install_bpf_program(handle, filter) < 0) 2345 /* install_bpf_program() filled in errbuf */ 2346 return -1; 2347 2348 /* 2349 * Run user level packet filter by default. Will be overriden if 2350 * installing a kernel filter succeeds. 2351 */ 2352 handle->md.use_bpf = 0; 2353 2354 /* Install kernel level filter if possible */ 2355 2356 #ifdef SO_ATTACH_FILTER 2357 #ifdef USHRT_MAX 2358 if (handle->fcode.bf_len > USHRT_MAX) { 2359 /* 2360 * fcode.len is an unsigned short for current kernel. 2361 * I have yet to see BPF-Code with that much 2362 * instructions but still it is possible. So for the 2363 * sake of correctness I added this check. 2364 */ 2365 fprintf(stderr, "Warning: Filter too complex for kernel\n"); 2366 fcode.len = 0; 2367 fcode.filter = NULL; 2368 can_filter_in_kernel = 0; 2369 } else 2370 #endif /* USHRT_MAX */ 2371 { 2372 /* 2373 * Oh joy, the Linux kernel uses struct sock_fprog instead 2374 * of struct bpf_program and of course the length field is 2375 * of different size. Pointed out by Sebastian 2376 * 2377 * Oh, and we also need to fix it up so that all "ret" 2378 * instructions with non-zero operands have 65535 as the 2379 * operand if we're not capturing in memory-mapped modee, 2380 * and so that, if we're in cooked mode, all memory-reference 2381 * instructions use special magic offsets in references to 2382 * the link-layer header and assume that the link-layer 2383 * payload begins at 0; "fix_program()" will do that. 2384 */ 2385 switch (fix_program(handle, &fcode, is_mmapped)) { 2386 2387 case -1: 2388 default: 2389 /* 2390 * Fatal error; just quit. 2391 * (The "default" case shouldn't happen; we 2392 * return -1 for that reason.) 2393 */ 2394 return -1; 2395 2396 case 0: 2397 /* 2398 * The program performed checks that we can't make 2399 * work in the kernel. 2400 */ 2401 can_filter_in_kernel = 0; 2402 break; 2403 2404 case 1: 2405 /* 2406 * We have a filter that'll work in the kernel. 2407 */ 2408 can_filter_in_kernel = 1; 2409 break; 2410 } 2411 } 2412 2413 /* 2414 * NOTE: at this point, we've set both the "len" and "filter" 2415 * fields of "fcode". As of the 2.6.32.4 kernel, at least, 2416 * those are the only members of the "sock_fprog" structure, 2417 * so we initialize every member of that structure. 2418 * 2419 * If there is anything in "fcode" that is not initialized, 2420 * it is either a field added in a later kernel, or it's 2421 * padding. 2422 * 2423 * If a new field is added, this code needs to be updated 2424 * to set it correctly. 2425 * 2426 * If there are no other fields, then: 2427 * 2428 * if the Linux kernel looks at the padding, it's 2429 * buggy; 2430 * 2431 * if the Linux kernel doesn't look at the padding, 2432 * then if some tool complains that we're passing 2433 * uninitialized data to the kernel, then the tool 2434 * is buggy and needs to understand that it's just 2435 * padding. 2436 */ 2437 if (can_filter_in_kernel) { 2438 if ((err = set_kernel_filter(handle, &fcode)) == 0) 2439 { 2440 /* Installation succeded - using kernel filter. */ 2441 handle->md.use_bpf = 1; 2442 } 2443 else if (err == -1) /* Non-fatal error */ 2444 { 2445 /* 2446 * Print a warning if we weren't able to install 2447 * the filter for a reason other than "this kernel 2448 * isn't configured to support socket filters. 2449 */ 2450 if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) { 2451 fprintf(stderr, 2452 "Warning: Kernel filter failed: %s\n", 2453 pcap_strerror(errno)); 2454 } 2455 } 2456 } 2457 2458 /* 2459 * If we're not using the kernel filter, get rid of any kernel 2460 * filter that might've been there before, e.g. because the 2461 * previous filter could work in the kernel, or because some other 2462 * code attached a filter to the socket by some means other than 2463 * calling "pcap_setfilter()". Otherwise, the kernel filter may 2464 * filter out packets that would pass the new userland filter. 2465 */ 2466 if (!handle->md.use_bpf) 2467 reset_kernel_filter(handle); 2468 2469 /* 2470 * Free up the copy of the filter that was made by "fix_program()". 2471 */ 2472 if (fcode.filter != NULL) 2473 free(fcode.filter); 2474 2475 if (err == -2) 2476 /* Fatal error */ 2477 return -1; 2478 #endif /* SO_ATTACH_FILTER */ 2479 2480 return 0; 2481 } 2482 2483 static int 2484 pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) 2485 { 2486 return pcap_setfilter_linux_common(handle, filter, 0); 2487 } 2488 2489 2490 /* 2491 * Set direction flag: Which packets do we accept on a forwarding 2492 * single device? IN, OUT or both? 2493 */ 2494 static int 2495 pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d) 2496 { 2497 #ifdef HAVE_PF_PACKET_SOCKETS 2498 if (!handle->md.sock_packet) { 2499 handle->direction = d; 2500 return 0; 2501 } 2502 #endif 2503 /* 2504 * We're not using PF_PACKET sockets, so we can't determine 2505 * the direction of the packet. 2506 */ 2507 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 2508 "Setting direction is not supported on SOCK_PACKET sockets"); 2509 return -1; 2510 } 2511 2512 #ifdef HAVE_PF_PACKET_SOCKETS 2513 /* 2514 * Map the PACKET_ value to a LINUX_SLL_ value; we 2515 * want the same numerical value to be used in 2516 * the link-layer header even if the numerical values 2517 * for the PACKET_ #defines change, so that programs 2518 * that look at the packet type field will always be 2519 * able to handle DLT_LINUX_SLL captures. 2520 */ 2521 static short int 2522 map_packet_type_to_sll_type(short int sll_pkttype) 2523 { 2524 switch (sll_pkttype) { 2525 2526 case PACKET_HOST: 2527 return htons(LINUX_SLL_HOST); 2528 2529 case PACKET_BROADCAST: 2530 return htons(LINUX_SLL_BROADCAST); 2531 2532 case PACKET_MULTICAST: 2533 return htons(LINUX_SLL_MULTICAST); 2534 2535 case PACKET_OTHERHOST: 2536 return htons(LINUX_SLL_OTHERHOST); 2537 2538 case PACKET_OUTGOING: 2539 return htons(LINUX_SLL_OUTGOING); 2540 2541 default: 2542 return -1; 2543 } 2544 } 2545 #endif 2546 2547 /* 2548 * Linux uses the ARP hardware type to identify the type of an 2549 * interface. pcap uses the DLT_xxx constants for this. This 2550 * function takes a pointer to a "pcap_t", and an ARPHRD_xxx 2551 * constant, as arguments, and sets "handle->linktype" to the 2552 * appropriate DLT_XXX constant and sets "handle->offset" to 2553 * the appropriate value (to make "handle->offset" plus link-layer 2554 * header length be a multiple of 4, so that the link-layer payload 2555 * will be aligned on a 4-byte boundary when capturing packets). 2556 * (If the offset isn't set here, it'll be 0; add code as appropriate 2557 * for cases where it shouldn't be 0.) 2558 * 2559 * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture 2560 * in cooked mode; otherwise, we can't use cooked mode, so we have 2561 * to pick some type that works in raw mode, or fail. 2562 * 2563 * Sets the link type to -1 if unable to map the type. 2564 */ 2565 static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok) 2566 { 2567 switch (arptype) { 2568 2569 case ARPHRD_ETHER: 2570 /* 2571 * This is (presumably) a real Ethernet capture; give it a 2572 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so 2573 * that an application can let you choose it, in case you're 2574 * capturing DOCSIS traffic that a Cisco Cable Modem 2575 * Termination System is putting out onto an Ethernet (it 2576 * doesn't put an Ethernet header onto the wire, it puts raw 2577 * DOCSIS frames out on the wire inside the low-level 2578 * Ethernet framing). 2579 * 2580 * XXX - are there any sorts of "fake Ethernet" that have 2581 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as 2582 * a Cisco CMTS won't put traffic onto it or get traffic 2583 * bridged onto it? ISDN is handled in "activate_new()", 2584 * as we fall back on cooked mode there; are there any 2585 * others? 2586 */ 2587 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); 2588 /* 2589 * If that fails, just leave the list empty. 2590 */ 2591 if (handle->dlt_list != NULL) { 2592 handle->dlt_list[0] = DLT_EN10MB; 2593 handle->dlt_list[1] = DLT_DOCSIS; 2594 handle->dlt_count = 2; 2595 } 2596 /* FALLTHROUGH */ 2597 2598 case ARPHRD_METRICOM: 2599 case ARPHRD_LOOPBACK: 2600 handle->linktype = DLT_EN10MB; 2601 handle->offset = 2; 2602 break; 2603 2604 case ARPHRD_EETHER: 2605 handle->linktype = DLT_EN3MB; 2606 break; 2607 2608 case ARPHRD_AX25: 2609 handle->linktype = DLT_AX25_KISS; 2610 break; 2611 2612 case ARPHRD_PRONET: 2613 handle->linktype = DLT_PRONET; 2614 break; 2615 2616 case ARPHRD_CHAOS: 2617 handle->linktype = DLT_CHAOS; 2618 break; 2619 #ifndef ARPHRD_CAN 2620 #define ARPHRD_CAN 280 2621 #endif 2622 case ARPHRD_CAN: 2623 handle->linktype = DLT_CAN_SOCKETCAN; 2624 break; 2625 2626 #ifndef ARPHRD_IEEE802_TR 2627 #define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ 2628 #endif 2629 case ARPHRD_IEEE802_TR: 2630 case ARPHRD_IEEE802: 2631 handle->linktype = DLT_IEEE802; 2632 handle->offset = 2; 2633 break; 2634 2635 case ARPHRD_ARCNET: 2636 handle->linktype = DLT_ARCNET_LINUX; 2637 break; 2638 2639 #ifndef ARPHRD_FDDI /* From Linux 2.2.13 */ 2640 #define ARPHRD_FDDI 774 2641 #endif 2642 case ARPHRD_FDDI: 2643 handle->linktype = DLT_FDDI; 2644 handle->offset = 3; 2645 break; 2646 2647 #ifndef ARPHRD_ATM /* FIXME: How to #include this? */ 2648 #define ARPHRD_ATM 19 2649 #endif 2650 case ARPHRD_ATM: 2651 /* 2652 * The Classical IP implementation in ATM for Linux 2653 * supports both what RFC 1483 calls "LLC Encapsulation", 2654 * in which each packet has an LLC header, possibly 2655 * with a SNAP header as well, prepended to it, and 2656 * what RFC 1483 calls "VC Based Multiplexing", in which 2657 * different virtual circuits carry different network 2658 * layer protocols, and no header is prepended to packets. 2659 * 2660 * They both have an ARPHRD_ type of ARPHRD_ATM, so 2661 * you can't use the ARPHRD_ type to find out whether 2662 * captured packets will have an LLC header, and, 2663 * while there's a socket ioctl to *set* the encapsulation 2664 * type, there's no ioctl to *get* the encapsulation type. 2665 * 2666 * This means that 2667 * 2668 * programs that dissect Linux Classical IP frames 2669 * would have to check for an LLC header and, 2670 * depending on whether they see one or not, dissect 2671 * the frame as LLC-encapsulated or as raw IP (I 2672 * don't know whether there's any traffic other than 2673 * IP that would show up on the socket, or whether 2674 * there's any support for IPv6 in the Linux 2675 * Classical IP code); 2676 * 2677 * filter expressions would have to compile into 2678 * code that checks for an LLC header and does 2679 * the right thing. 2680 * 2681 * Both of those are a nuisance - and, at least on systems 2682 * that support PF_PACKET sockets, we don't have to put 2683 * up with those nuisances; instead, we can just capture 2684 * in cooked mode. That's what we'll do, if we can. 2685 * Otherwise, we'll just fail. 2686 */ 2687 if (cooked_ok) 2688 handle->linktype = DLT_LINUX_SLL; 2689 else 2690 handle->linktype = -1; 2691 break; 2692 2693 #ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */ 2694 #define ARPHRD_IEEE80211 801 2695 #endif 2696 case ARPHRD_IEEE80211: 2697 handle->linktype = DLT_IEEE802_11; 2698 break; 2699 2700 #ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */ 2701 #define ARPHRD_IEEE80211_PRISM 802 2702 #endif 2703 case ARPHRD_IEEE80211_PRISM: 2704 handle->linktype = DLT_PRISM_HEADER; 2705 break; 2706 2707 #ifndef ARPHRD_IEEE80211_RADIOTAP /* new */ 2708 #define ARPHRD_IEEE80211_RADIOTAP 803 2709 #endif 2710 case ARPHRD_IEEE80211_RADIOTAP: 2711 handle->linktype = DLT_IEEE802_11_RADIO; 2712 break; 2713 2714 case ARPHRD_PPP: 2715 /* 2716 * Some PPP code in the kernel supplies no link-layer 2717 * header whatsoever to PF_PACKET sockets; other PPP 2718 * code supplies PPP link-layer headers ("syncppp.c"); 2719 * some PPP code might supply random link-layer 2720 * headers (PPP over ISDN - there's code in Ethereal, 2721 * for example, to cope with PPP-over-ISDN captures 2722 * with which the Ethereal developers have had to cope, 2723 * heuristically trying to determine which of the 2724 * oddball link-layer headers particular packets have). 2725 * 2726 * As such, we just punt, and run all PPP interfaces 2727 * in cooked mode, if we can; otherwise, we just treat 2728 * it as DLT_RAW, for now - if somebody needs to capture, 2729 * on a 2.0[.x] kernel, on PPP devices that supply a 2730 * link-layer header, they'll have to add code here to 2731 * map to the appropriate DLT_ type (possibly adding a 2732 * new DLT_ type, if necessary). 2733 */ 2734 if (cooked_ok) 2735 handle->linktype = DLT_LINUX_SLL; 2736 else { 2737 /* 2738 * XXX - handle ISDN types here? We can't fall 2739 * back on cooked sockets, so we'd have to 2740 * figure out from the device name what type of 2741 * link-layer encapsulation it's using, and map 2742 * that to an appropriate DLT_ value, meaning 2743 * we'd map "isdnN" devices to DLT_RAW (they 2744 * supply raw IP packets with no link-layer 2745 * header) and "isdY" devices to a new DLT_I4L_IP 2746 * type that has only an Ethernet packet type as 2747 * a link-layer header. 2748 * 2749 * But sometimes we seem to get random crap 2750 * in the link-layer header when capturing on 2751 * ISDN devices.... 2752 */ 2753 handle->linktype = DLT_RAW; 2754 } 2755 break; 2756 2757 #ifndef ARPHRD_CISCO 2758 #define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */ 2759 #endif 2760 case ARPHRD_CISCO: 2761 handle->linktype = DLT_C_HDLC; 2762 break; 2763 2764 /* Not sure if this is correct for all tunnels, but it 2765 * works for CIPE */ 2766 case ARPHRD_TUNNEL: 2767 #ifndef ARPHRD_SIT 2768 #define ARPHRD_SIT 776 /* From Linux 2.2.13 */ 2769 #endif 2770 case ARPHRD_SIT: 2771 case ARPHRD_CSLIP: 2772 case ARPHRD_SLIP6: 2773 case ARPHRD_CSLIP6: 2774 case ARPHRD_ADAPT: 2775 case ARPHRD_SLIP: 2776 #ifndef ARPHRD_RAWHDLC 2777 #define ARPHRD_RAWHDLC 518 2778 #endif 2779 case ARPHRD_RAWHDLC: 2780 #ifndef ARPHRD_DLCI 2781 #define ARPHRD_DLCI 15 2782 #endif 2783 case ARPHRD_DLCI: 2784 /* 2785 * XXX - should some of those be mapped to DLT_LINUX_SLL 2786 * instead? Should we just map all of them to DLT_LINUX_SLL? 2787 */ 2788 handle->linktype = DLT_RAW; 2789 break; 2790 2791 #ifndef ARPHRD_FRAD 2792 #define ARPHRD_FRAD 770 2793 #endif 2794 case ARPHRD_FRAD: 2795 handle->linktype = DLT_FRELAY; 2796 break; 2797 2798 case ARPHRD_LOCALTLK: 2799 handle->linktype = DLT_LTALK; 2800 break; 2801 2802 #ifndef ARPHRD_FCPP 2803 #define ARPHRD_FCPP 784 2804 #endif 2805 case ARPHRD_FCPP: 2806 #ifndef ARPHRD_FCAL 2807 #define ARPHRD_FCAL 785 2808 #endif 2809 case ARPHRD_FCAL: 2810 #ifndef ARPHRD_FCPL 2811 #define ARPHRD_FCPL 786 2812 #endif 2813 case ARPHRD_FCPL: 2814 #ifndef ARPHRD_FCFABRIC 2815 #define ARPHRD_FCFABRIC 787 2816 #endif 2817 case ARPHRD_FCFABRIC: 2818 /* 2819 * We assume that those all mean RFC 2625 IP-over- 2820 * Fibre Channel, with the RFC 2625 header at 2821 * the beginning of the packet. 2822 */ 2823 handle->linktype = DLT_IP_OVER_FC; 2824 break; 2825 2826 #ifndef ARPHRD_IRDA 2827 #define ARPHRD_IRDA 783 2828 #endif 2829 case ARPHRD_IRDA: 2830 /* Don't expect IP packet out of this interfaces... */ 2831 handle->linktype = DLT_LINUX_IRDA; 2832 /* We need to save packet direction for IrDA decoding, 2833 * so let's use "Linux-cooked" mode. Jean II */ 2834 //handle->md.cooked = 1; 2835 break; 2836 2837 /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation 2838 * is needed, please report it to <daniele@orlandi.com> */ 2839 #ifndef ARPHRD_LAPD 2840 #define ARPHRD_LAPD 8445 2841 #endif 2842 case ARPHRD_LAPD: 2843 /* Don't expect IP packet out of this interfaces... */ 2844 handle->linktype = DLT_LINUX_LAPD; 2845 break; 2846 2847 #ifndef ARPHRD_NONE 2848 #define ARPHRD_NONE 0xFFFE 2849 #endif 2850 case ARPHRD_NONE: 2851 /* 2852 * No link-layer header; packets are just IP 2853 * packets, so use DLT_RAW. 2854 */ 2855 handle->linktype = DLT_RAW; 2856 break; 2857 2858 #ifndef ARPHRD_IEEE802154 2859 #define ARPHRD_IEEE802154 804 2860 #endif 2861 case ARPHRD_IEEE802154: 2862 handle->linktype = DLT_IEEE802_15_4_NOFCS; 2863 break; 2864 2865 default: 2866 handle->linktype = -1; 2867 break; 2868 } 2869 } 2870 2871 /* ===== Functions to interface to the newer kernels ================== */ 2872 2873 /* 2874 * Try to open a packet socket using the new kernel PF_PACKET interface. 2875 * Returns 1 on success, 0 on an error that means the new interface isn't 2876 * present (so the old SOCK_PACKET interface should be tried), and a 2877 * PCAP_ERROR_ value on an error that means that the old mechanism won't 2878 * work either (so it shouldn't be tried). 2879 */ 2880 static int 2881 activate_new(pcap_t *handle) 2882 { 2883 #ifdef HAVE_PF_PACKET_SOCKETS 2884 const char *device = handle->opt.source; 2885 int is_any_device = (strcmp(device, "any") == 0); 2886 int sock_fd = -1, arptype; 2887 #ifdef HAVE_PACKET_AUXDATA 2888 int val; 2889 #endif 2890 int err = 0; 2891 struct packet_mreq mr; 2892 2893 /* 2894 * Open a socket with protocol family packet. If the 2895 * "any" device was specified, we open a SOCK_DGRAM 2896 * socket for the cooked interface, otherwise we first 2897 * try a SOCK_RAW socket for the raw interface. 2898 */ 2899 sock_fd = is_any_device ? 2900 socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) : 2901 socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); 2902 2903 if (sock_fd == -1) { 2904 if (errno == EINVAL || errno == EAFNOSUPPORT) { 2905 /* 2906 * We don't support PF_PACKET/SOCK_whatever 2907 * sockets; try the old mechanism. 2908 */ 2909 return 0; 2910 } 2911 2912 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", 2913 pcap_strerror(errno) ); 2914 if (errno == EPERM || errno == EACCES) { 2915 /* 2916 * You don't have permission to open the 2917 * socket. 2918 */ 2919 return PCAP_ERROR_PERM_DENIED; 2920 } else { 2921 /* 2922 * Other error. 2923 */ 2924 return PCAP_ERROR; 2925 } 2926 } 2927 2928 /* It seems the kernel supports the new interface. */ 2929 handle->md.sock_packet = 0; 2930 2931 /* 2932 * Get the interface index of the loopback device. 2933 * If the attempt fails, don't fail, just set the 2934 * "md.lo_ifindex" to -1. 2935 * 2936 * XXX - can there be more than one device that loops 2937 * packets back, i.e. devices other than "lo"? If so, 2938 * we'd need to find them all, and have an array of 2939 * indices for them, and check all of them in 2940 * "pcap_read_packet()". 2941 */ 2942 handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf); 2943 2944 /* 2945 * Default value for offset to align link-layer payload 2946 * on a 4-byte boundary. 2947 */ 2948 handle->offset = 0; 2949 2950 /* 2951 * What kind of frames do we have to deal with? Fall back 2952 * to cooked mode if we have an unknown interface type 2953 * or a type we know doesn't work well in raw mode. 2954 */ 2955 if (!is_any_device) { 2956 /* Assume for now we don't need cooked mode. */ 2957 handle->md.cooked = 0; 2958 2959 if (handle->opt.rfmon) { 2960 /* 2961 * We were asked to turn on monitor mode. 2962 * Do so before we get the link-layer type, 2963 * because entering monitor mode could change 2964 * the link-layer type. 2965 */ 2966 err = enter_rfmon_mode(handle, sock_fd, device); 2967 if (err < 0) { 2968 /* Hard failure */ 2969 close(sock_fd); 2970 return err; 2971 } 2972 if (err == 0) { 2973 /* 2974 * Nothing worked for turning monitor mode 2975 * on. 2976 */ 2977 close(sock_fd); 2978 return PCAP_ERROR_RFMON_NOTSUP; 2979 } 2980 2981 /* 2982 * Either monitor mode has been turned on for 2983 * the device, or we've been given a different 2984 * device to open for monitor mode. If we've 2985 * been given a different device, use it. 2986 */ 2987 if (handle->md.mondevice != NULL) 2988 device = handle->md.mondevice; 2989 } 2990 arptype = iface_get_arptype(sock_fd, device, handle->errbuf); 2991 if (arptype < 0) { 2992 close(sock_fd); 2993 return arptype; 2994 } 2995 map_arphrd_to_dlt(handle, arptype, 1); 2996 if (handle->linktype == -1 || 2997 handle->linktype == DLT_LINUX_SLL || 2998 handle->linktype == DLT_LINUX_IRDA || 2999 handle->linktype == DLT_LINUX_LAPD || 3000 (handle->linktype == DLT_EN10MB && 3001 (strncmp("isdn", device, 4) == 0 || 3002 strncmp("isdY", device, 4) == 0))) { 3003 /* 3004 * Unknown interface type (-1), or a 3005 * device we explicitly chose to run 3006 * in cooked mode (e.g., PPP devices), 3007 * or an ISDN device (whose link-layer 3008 * type we can only determine by using 3009 * APIs that may be different on different 3010 * kernels) - reopen in cooked mode. 3011 */ 3012 if (close(sock_fd) == -1) { 3013 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3014 "close: %s", pcap_strerror(errno)); 3015 return PCAP_ERROR; 3016 } 3017 sock_fd = socket(PF_PACKET, SOCK_DGRAM, 3018 htons(ETH_P_ALL)); 3019 if (sock_fd == -1) { 3020 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3021 "socket: %s", pcap_strerror(errno)); 3022 if (errno == EPERM || errno == EACCES) { 3023 /* 3024 * You don't have permission to 3025 * open the socket. 3026 */ 3027 return PCAP_ERROR_PERM_DENIED; 3028 } else { 3029 /* 3030 * Other error. 3031 */ 3032 return PCAP_ERROR; 3033 } 3034 } 3035 handle->md.cooked = 1; 3036 3037 /* 3038 * Get rid of any link-layer type list 3039 * we allocated - this only supports cooked 3040 * capture. 3041 */ 3042 if (handle->dlt_list != NULL) { 3043 free(handle->dlt_list); 3044 handle->dlt_list = NULL; 3045 handle->dlt_count = 0; 3046 } 3047 3048 if (handle->linktype == -1) { 3049 /* 3050 * Warn that we're falling back on 3051 * cooked mode; we may want to 3052 * update "map_arphrd_to_dlt()" 3053 * to handle the new type. 3054 */ 3055 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3056 "arptype %d not " 3057 "supported by libpcap - " 3058 "falling back to cooked " 3059 "socket", 3060 arptype); 3061 } 3062 3063 /* 3064 * IrDA capture is not a real "cooked" capture, 3065 * it's IrLAP frames, not IP packets. The 3066 * same applies to LAPD capture. 3067 */ 3068 if (handle->linktype != DLT_LINUX_IRDA && 3069 handle->linktype != DLT_LINUX_LAPD) 3070 handle->linktype = DLT_LINUX_SLL; 3071 } 3072 3073 handle->md.ifindex = iface_get_id(sock_fd, device, 3074 handle->errbuf); 3075 if (handle->md.ifindex == -1) { 3076 close(sock_fd); 3077 return PCAP_ERROR; 3078 } 3079 3080 if ((err = iface_bind(sock_fd, handle->md.ifindex, 3081 handle->errbuf)) != 1) { 3082 close(sock_fd); 3083 if (err < 0) 3084 return err; 3085 else 3086 return 0; /* try old mechanism */ 3087 } 3088 } else { 3089 /* 3090 * The "any" device. 3091 */ 3092 if (handle->opt.rfmon) { 3093 /* 3094 * It doesn't support monitor mode. 3095 */ 3096 return PCAP_ERROR_RFMON_NOTSUP; 3097 } 3098 3099 /* 3100 * It uses cooked mode. 3101 */ 3102 handle->md.cooked = 1; 3103 handle->linktype = DLT_LINUX_SLL; 3104 3105 /* 3106 * We're not bound to a device. 3107 * For now, we're using this as an indication 3108 * that we can't transmit; stop doing that only 3109 * if we figure out how to transmit in cooked 3110 * mode. 3111 */ 3112 handle->md.ifindex = -1; 3113 } 3114 3115 /* 3116 * Select promiscuous mode on if "promisc" is set. 3117 * 3118 * Do not turn allmulti mode on if we don't select 3119 * promiscuous mode - on some devices (e.g., Orinoco 3120 * wireless interfaces), allmulti mode isn't supported 3121 * and the driver implements it by turning promiscuous 3122 * mode on, and that screws up the operation of the 3123 * card as a normal networking interface, and on no 3124 * other platform I know of does starting a non- 3125 * promiscuous capture affect which multicast packets 3126 * are received by the interface. 3127 */ 3128 3129 /* 3130 * Hmm, how can we set promiscuous mode on all interfaces? 3131 * I am not sure if that is possible at all. For now, we 3132 * silently ignore attempts to turn promiscuous mode on 3133 * for the "any" device (so you don't have to explicitly 3134 * disable it in programs such as tcpdump). 3135 */ 3136 3137 if (!is_any_device && handle->opt.promisc) { 3138 memset(&mr, 0, sizeof(mr)); 3139 mr.mr_ifindex = handle->md.ifindex; 3140 mr.mr_type = PACKET_MR_PROMISC; 3141 if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, 3142 &mr, sizeof(mr)) == -1) { 3143 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3144 "setsockopt: %s", pcap_strerror(errno)); 3145 close(sock_fd); 3146 return PCAP_ERROR; 3147 } 3148 } 3149 3150 /* Enable auxillary data if supported and reserve room for 3151 * reconstructing VLAN headers. */ 3152 #ifdef HAVE_PACKET_AUXDATA 3153 val = 1; 3154 if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, 3155 sizeof(val)) == -1 && errno != ENOPROTOOPT) { 3156 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3157 "setsockopt: %s", pcap_strerror(errno)); 3158 close(sock_fd); 3159 return PCAP_ERROR; 3160 } 3161 handle->offset += VLAN_TAG_LEN; 3162 #endif /* HAVE_PACKET_AUXDATA */ 3163 3164 /* 3165 * This is a 2.2[.x] or later kernel (we know that 3166 * because we're not using a SOCK_PACKET socket - 3167 * PF_PACKET is supported only in 2.2 and later 3168 * kernels). 3169 * 3170 * We can safely pass "recvfrom()" a byte count 3171 * based on the snapshot length. 3172 * 3173 * If we're in cooked mode, make the snapshot length 3174 * large enough to hold a "cooked mode" header plus 3175 * 1 byte of packet data (so we don't pass a byte 3176 * count of 0 to "recvfrom()"). 3177 */ 3178 if (handle->md.cooked) { 3179 if (handle->snapshot < SLL_HDR_LEN + 1) 3180 handle->snapshot = SLL_HDR_LEN + 1; 3181 } 3182 handle->bufsize = handle->snapshot; 3183 3184 /* Save the socket FD in the pcap structure */ 3185 handle->fd = sock_fd; 3186 3187 return 1; 3188 #else 3189 strncpy(ebuf, 3190 "New packet capturing interface not supported by build " 3191 "environment", PCAP_ERRBUF_SIZE); 3192 return 0; 3193 #endif 3194 } 3195 3196 #ifdef HAVE_PACKET_RING 3197 /* 3198 * Attempt to activate with memory-mapped access. 3199 * 3200 * On success, returns 1, and sets *status to 0 if there are no warnings 3201 * or to a PCAP_WARNING_ code if there is a warning. 3202 * 3203 * On failure due to lack of support for memory-mapped capture, returns 3204 * 0. 3205 * 3206 * On error, returns -1, and sets *status to the appropriate error code; 3207 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. 3208 */ 3209 static int 3210 activate_mmap(pcap_t *handle, int *status) 3211 { 3212 int ret; 3213 3214 /* 3215 * Attempt to allocate a buffer to hold the contents of one 3216 * packet, for use by the oneshot callback. 3217 */ 3218 handle->md.oneshot_buffer = malloc(handle->snapshot); 3219 if (handle->md.oneshot_buffer == NULL) { 3220 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3221 "can't allocate oneshot buffer: %s", 3222 pcap_strerror(errno)); 3223 *status = PCAP_ERROR; 3224 return -1; 3225 } 3226 3227 if (handle->opt.buffer_size == 0) { 3228 /* by default request 2M for the ring buffer */ 3229 handle->opt.buffer_size = 2*1024*1024; 3230 } 3231 ret = prepare_tpacket_socket(handle); 3232 if (ret == -1) { 3233 free(handle->md.oneshot_buffer); 3234 *status = PCAP_ERROR; 3235 return ret; 3236 } 3237 ret = create_ring(handle, status); 3238 if (ret == 0) { 3239 /* 3240 * We don't support memory-mapped capture; our caller 3241 * will fall back on reading from the socket. 3242 */ 3243 free(handle->md.oneshot_buffer); 3244 return 0; 3245 } 3246 if (ret == -1) { 3247 /* 3248 * Error attempting to enable memory-mapped capture; 3249 * fail. create_ring() has set *status. 3250 */ 3251 free(handle->md.oneshot_buffer); 3252 return -1; 3253 } 3254 3255 /* 3256 * Success. *status has been set either to 0 if there are no 3257 * warnings or to a PCAP_WARNING_ value if there is a warning. 3258 * 3259 * Override some defaults and inherit the other fields from 3260 * activate_new. 3261 * handle->offset is used to get the current position into the rx ring. 3262 * handle->cc is used to store the ring size. 3263 */ 3264 handle->read_op = pcap_read_linux_mmap; 3265 handle->cleanup_op = pcap_cleanup_linux_mmap; 3266 handle->setfilter_op = pcap_setfilter_linux_mmap; 3267 handle->setnonblock_op = pcap_setnonblock_mmap; 3268 handle->getnonblock_op = pcap_getnonblock_mmap; 3269 handle->oneshot_callback = pcap_oneshot_mmap; 3270 handle->selectable_fd = handle->fd; 3271 return 1; 3272 } 3273 #else /* HAVE_PACKET_RING */ 3274 static int 3275 activate_mmap(pcap_t *handle _U_, int *status _U_) 3276 { 3277 return 0; 3278 } 3279 #endif /* HAVE_PACKET_RING */ 3280 3281 #ifdef HAVE_PACKET_RING 3282 /* 3283 * Attempt to set the socket to version 2 of the memory-mapped header. 3284 * Return 1 if we succeed or if we fail because version 2 isn't 3285 * supported; return -1 on any other error, and set handle->errbuf. 3286 */ 3287 static int 3288 prepare_tpacket_socket(pcap_t *handle) 3289 { 3290 #ifdef HAVE_TPACKET2 3291 socklen_t len; 3292 int val; 3293 #endif 3294 3295 handle->md.tp_version = TPACKET_V1; 3296 handle->md.tp_hdrlen = sizeof(struct tpacket_hdr); 3297 3298 #ifdef HAVE_TPACKET2 3299 /* Probe whether kernel supports TPACKET_V2 */ 3300 val = TPACKET_V2; 3301 len = sizeof(val); 3302 if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { 3303 if (errno == ENOPROTOOPT) 3304 return 1; /* no - just drive on */ 3305 3306 /* Yes - treat as a failure. */ 3307 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3308 "can't get TPACKET_V2 header len on packet socket: %s", 3309 pcap_strerror(errno)); 3310 return -1; 3311 } 3312 handle->md.tp_hdrlen = val; 3313 3314 val = TPACKET_V2; 3315 if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, 3316 sizeof(val)) < 0) { 3317 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3318 "can't activate TPACKET_V2 on packet socket: %s", 3319 pcap_strerror(errno)); 3320 return -1; 3321 } 3322 handle->md.tp_version = TPACKET_V2; 3323 3324 /* Reserve space for VLAN tag reconstruction */ 3325 val = VLAN_TAG_LEN; 3326 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val, 3327 sizeof(val)) < 0) { 3328 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3329 "can't set up reserve on packet socket: %s", 3330 pcap_strerror(errno)); 3331 return -1; 3332 } 3333 3334 #endif /* HAVE_TPACKET2 */ 3335 return 1; 3336 } 3337 3338 /* 3339 * Attempt to set up memory-mapped access. 3340 * 3341 * On success, returns 1, and sets *status to 0 if there are no warnings 3342 * or to a PCAP_WARNING_ code if there is a warning. 3343 * 3344 * On failure due to lack of support for memory-mapped capture, returns 3345 * 0. 3346 * 3347 * On error, returns -1, and sets *status to the appropriate error code; 3348 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. 3349 */ 3350 static int 3351 create_ring(pcap_t *handle, int *status) 3352 { 3353 unsigned i, j, frames_per_block; 3354 struct tpacket_req req; 3355 socklen_t len; 3356 unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff; 3357 unsigned int frame_size; 3358 3359 /* 3360 * Start out assuming no warnings or errors. 3361 */ 3362 *status = 0; 3363 3364 /* Note that with large snapshot length (say 64K, which is the default 3365 * for recent versions of tcpdump, the value that "-s 0" has given 3366 * for a long time with tcpdump, and the default in Wireshark/TShark), 3367 * if we use the snapshot length to calculate the frame length, 3368 * only a few frames will be available in the ring even with pretty 3369 * large ring size (and a lot of memory will be unused). 3370 * 3371 * Ideally, we should choose a frame length based on the 3372 * minimum of the specified snapshot length and the maximum 3373 * packet size. That's not as easy as it sounds; consider, for 3374 * example, an 802.11 interface in monitor mode, where the 3375 * frame would include a radiotap header, where the maximum 3376 * radiotap header length is device-dependent. 3377 * 3378 * So, for now, we just do this for Ethernet devices, where 3379 * there's no metadata header, and the link-layer header is 3380 * fixed length. We can get the maximum packet size by 3381 * adding 18, the Ethernet header length plus the CRC length 3382 * (just in case we happen to get the CRC in the packet), to 3383 * the MTU of the interface; we fetch the MTU in the hopes 3384 * that it reflects support for jumbo frames. (Even if the 3385 * interface is just being used for passive snooping, the driver 3386 * might set the size of buffers in the receive ring based on 3387 * the MTU, so that the MTU limits the maximum size of packets 3388 * that we can receive.) 3389 * 3390 * We don't do that if segmentation/fragmentation or receive 3391 * offload are enabled, so we don't get rudely surprised by 3392 * "packets" bigger than the MTU. */ 3393 frame_size = handle->snapshot; 3394 if (handle->linktype == DLT_EN10MB) { 3395 int mtu; 3396 int offload; 3397 3398 offload = iface_get_offload(handle); 3399 if (offload == -1) { 3400 *status = PCAP_ERROR; 3401 return -1; 3402 } 3403 if (!offload) { 3404 mtu = iface_get_mtu(handle->fd, handle->opt.source, 3405 handle->errbuf); 3406 if (mtu == -1) { 3407 *status = PCAP_ERROR; 3408 return -1; 3409 } 3410 if (frame_size > mtu + 18) 3411 frame_size = mtu + 18; 3412 } 3413 } 3414 3415 /* NOTE: calculus matching those in tpacket_rcv() 3416 * in linux-2.6/net/packet/af_packet.c 3417 */ 3418 len = sizeof(sk_type); 3419 if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type, &len) < 0) { 3420 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); 3421 *status = PCAP_ERROR; 3422 return -1; 3423 } 3424 #ifdef PACKET_RESERVE 3425 len = sizeof(tp_reserve); 3426 if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, &len) < 0) { 3427 if (errno != ENOPROTOOPT) { 3428 /* 3429 * ENOPROTOOPT means "kernel doesn't support 3430 * PACKET_RESERVE", in which case we fall back 3431 * as best we can. 3432 */ 3433 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); 3434 *status = PCAP_ERROR; 3435 return -1; 3436 } 3437 tp_reserve = 0; /* older kernel, reserve not supported */ 3438 } 3439 #else 3440 tp_reserve = 0; /* older kernel, reserve not supported */ 3441 #endif 3442 maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE; 3443 /* XXX: in the kernel maclen is calculated from 3444 * LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len 3445 * in: packet_snd() in linux-2.6/net/packet/af_packet.c 3446 * then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c 3447 * then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c 3448 * but I see no way to get those sizes in userspace, 3449 * like for instance with an ifreq ioctl(); 3450 * the best thing I've found so far is MAX_HEADER in the kernel 3451 * part of linux-2.6/include/linux/netdevice.h 3452 * which goes up to 128+48=176; since pcap-linux.c defines 3453 * a MAX_LINKHEADER_SIZE of 256 which is greater than that, 3454 * let's use it.. maybe is it even large enough to directly 3455 * replace macoff.. 3456 */ 3457 tp_hdrlen = TPACKET_ALIGN(handle->md.tp_hdrlen) + sizeof(struct sockaddr_ll) ; 3458 netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve; 3459 /* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN of 3460 * netoff, which contradicts 3461 * linux-2.6/Documentation/networking/packet_mmap.txt 3462 * documenting that: 3463 * "- Gap, chosen so that packet data (Start+tp_net) 3464 * aligns to TPACKET_ALIGNMENT=16" 3465 */ 3466 /* NOTE: in linux-2.6/include/linux/skbuff.h: 3467 * "CPUs often take a performance hit 3468 * when accessing unaligned memory locations" 3469 */ 3470 macoff = netoff - maclen; 3471 req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size); 3472 req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; 3473 3474 /* compute the minumum block size that will handle this frame. 3475 * The block has to be page size aligned. 3476 * The max block size allowed by the kernel is arch-dependent and 3477 * it's not explicitly checked here. */ 3478 req.tp_block_size = getpagesize(); 3479 while (req.tp_block_size < req.tp_frame_size) 3480 req.tp_block_size <<= 1; 3481 3482 frames_per_block = req.tp_block_size/req.tp_frame_size; 3483 3484 /* 3485 * PACKET_TIMESTAMP was added after linux/net_tstamp.h was, 3486 * so we check for PACKET_TIMESTAMP. We check for 3487 * linux/net_tstamp.h just in case a system somehow has 3488 * PACKET_TIMESTAMP but not linux/net_tstamp.h; that might 3489 * be unnecessary. 3490 * 3491 * SIOCSHWTSTAMP was introduced in the patch that introduced 3492 * linux/net_tstamp.h, so we don't bother checking whether 3493 * SIOCSHWTSTAMP is defined (if your Linux system has 3494 * linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your 3495 * Linux system is badly broken). 3496 */ 3497 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) 3498 /* 3499 * If we were told to do so, ask the kernel and the driver 3500 * to use hardware timestamps. 3501 * 3502 * Hardware timestamps are only supported with mmapped 3503 * captures. 3504 */ 3505 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER || 3506 handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) { 3507 struct hwtstamp_config hwconfig; 3508 struct ifreq ifr; 3509 int timesource; 3510 3511 /* 3512 * Ask for hardware time stamps on all packets, 3513 * including transmitted packets. 3514 */ 3515 memset(&hwconfig, 0, sizeof(hwconfig)); 3516 hwconfig.tx_type = HWTSTAMP_TX_ON; 3517 hwconfig.rx_filter = HWTSTAMP_FILTER_ALL; 3518 3519 memset(&ifr, 0, sizeof(ifr)); 3520 strcpy(ifr.ifr_name, handle->opt.source); 3521 ifr.ifr_data = (void *)&hwconfig; 3522 3523 if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) { 3524 switch (errno) { 3525 3526 case EPERM: 3527 /* 3528 * Treat this as an error, as the 3529 * user should try to run this 3530 * with the appropriate privileges - 3531 * and, if they can't, shouldn't 3532 * try requesting hardware time stamps. 3533 */ 3534 *status = PCAP_ERROR_PERM_DENIED; 3535 return -1; 3536 3537 case EOPNOTSUPP: 3538 /* 3539 * Treat this as a warning, as the 3540 * only way to fix the warning is to 3541 * get an adapter that supports hardware 3542 * time stamps. We'll just fall back 3543 * on the standard host time stamps. 3544 */ 3545 *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP; 3546 break; 3547 3548 default: 3549 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3550 "SIOCSHWTSTAMP failed: %s", 3551 pcap_strerror(errno)); 3552 *status = PCAP_ERROR; 3553 return -1; 3554 } 3555 } else { 3556 /* 3557 * Well, that worked. Now specify the type of 3558 * hardware time stamp we want for this 3559 * socket. 3560 */ 3561 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) { 3562 /* 3563 * Hardware timestamp, synchronized 3564 * with the system clock. 3565 */ 3566 timesource = SOF_TIMESTAMPING_SYS_HARDWARE; 3567 } else { 3568 /* 3569 * PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware 3570 * timestamp, not synchronized with the 3571 * system clock. 3572 */ 3573 timesource = SOF_TIMESTAMPING_RAW_HARDWARE; 3574 } 3575 if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP, 3576 (void *)×ource, sizeof(timesource))) { 3577 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3578 "can't set PACKET_TIMESTAMP: %s", 3579 pcap_strerror(errno)); 3580 *status = PCAP_ERROR; 3581 return -1; 3582 } 3583 } 3584 } 3585 #endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */ 3586 3587 /* ask the kernel to create the ring */ 3588 retry: 3589 req.tp_block_nr = req.tp_frame_nr / frames_per_block; 3590 3591 /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ 3592 req.tp_frame_nr = req.tp_block_nr * frames_per_block; 3593 3594 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, 3595 (void *) &req, sizeof(req))) { 3596 if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { 3597 /* 3598 * Memory failure; try to reduce the requested ring 3599 * size. 3600 * 3601 * We used to reduce this by half -- do 5% instead. 3602 * That may result in more iterations and a longer 3603 * startup, but the user will be much happier with 3604 * the resulting buffer size. 3605 */ 3606 if (req.tp_frame_nr < 20) 3607 req.tp_frame_nr -= 1; 3608 else 3609 req.tp_frame_nr -= req.tp_frame_nr/20; 3610 goto retry; 3611 } 3612 if (errno == ENOPROTOOPT) { 3613 /* 3614 * We don't have ring buffer support in this kernel. 3615 */ 3616 return 0; 3617 } 3618 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3619 "can't create rx ring on packet socket: %s", 3620 pcap_strerror(errno)); 3621 *status = PCAP_ERROR; 3622 return -1; 3623 } 3624 3625 /* memory map the rx ring */ 3626 handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size; 3627 handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen, 3628 PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); 3629 if (handle->md.mmapbuf == MAP_FAILED) { 3630 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3631 "can't mmap rx ring: %s", pcap_strerror(errno)); 3632 3633 /* clear the allocated ring on error*/ 3634 destroy_ring(handle); 3635 *status = PCAP_ERROR; 3636 return -1; 3637 } 3638 3639 /* allocate a ring for each frame header pointer*/ 3640 handle->cc = req.tp_frame_nr; 3641 handle->buffer = malloc(handle->cc * sizeof(union thdr *)); 3642 if (!handle->buffer) { 3643 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3644 "can't allocate ring of frame headers: %s", 3645 pcap_strerror(errno)); 3646 3647 destroy_ring(handle); 3648 *status = PCAP_ERROR; 3649 return -1; 3650 } 3651 3652 /* fill the header ring with proper frame ptr*/ 3653 handle->offset = 0; 3654 for (i=0; i<req.tp_block_nr; ++i) { 3655 void *base = &handle->md.mmapbuf[i*req.tp_block_size]; 3656 for (j=0; j<frames_per_block; ++j, ++handle->offset) { 3657 RING_GET_FRAME(handle) = base; 3658 base += req.tp_frame_size; 3659 } 3660 } 3661 3662 handle->bufsize = req.tp_frame_size; 3663 handle->offset = 0; 3664 return 1; 3665 } 3666 3667 /* free all ring related resources*/ 3668 static void 3669 destroy_ring(pcap_t *handle) 3670 { 3671 /* tell the kernel to destroy the ring*/ 3672 struct tpacket_req req; 3673 memset(&req, 0, sizeof(req)); 3674 setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, 3675 (void *) &req, sizeof(req)); 3676 3677 /* if ring is mapped, unmap it*/ 3678 if (handle->md.mmapbuf) { 3679 /* do not test for mmap failure, as we can't recover from any error */ 3680 munmap(handle->md.mmapbuf, handle->md.mmapbuflen); 3681 handle->md.mmapbuf = NULL; 3682 } 3683 } 3684 3685 /* 3686 * Special one-shot callback, used for pcap_next() and pcap_next_ex(), 3687 * for Linux mmapped capture. 3688 * 3689 * The problem is that pcap_next() and pcap_next_ex() expect the packet 3690 * data handed to the callback to be valid after the callback returns, 3691 * but pcap_read_linux_mmap() has to release that packet as soon as 3692 * the callback returns (otherwise, the kernel thinks there's still 3693 * at least one unprocessed packet available in the ring, so a select() 3694 * will immediately return indicating that there's data to process), so, 3695 * in the callback, we have to make a copy of the packet. 3696 * 3697 * Yes, this means that, if the capture is using the ring buffer, using 3698 * pcap_next() or pcap_next_ex() requires more copies than using 3699 * pcap_loop() or pcap_dispatch(). If that bothers you, don't use 3700 * pcap_next() or pcap_next_ex(). 3701 */ 3702 static void 3703 pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, 3704 const u_char *bytes) 3705 { 3706 struct oneshot_userdata *sp = (struct oneshot_userdata *)user; 3707 3708 *sp->hdr = *h; 3709 memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen); 3710 *sp->pkt = sp->pd->md.oneshot_buffer; 3711 } 3712 3713 static void 3714 pcap_cleanup_linux_mmap( pcap_t *handle ) 3715 { 3716 destroy_ring(handle); 3717 if (handle->md.oneshot_buffer != NULL) { 3718 free(handle->md.oneshot_buffer); 3719 handle->md.oneshot_buffer = NULL; 3720 } 3721 pcap_cleanup_linux(handle); 3722 } 3723 3724 3725 static int 3726 pcap_getnonblock_mmap(pcap_t *p, char *errbuf) 3727 { 3728 /* use negative value of timeout to indicate non blocking ops */ 3729 return (p->md.timeout<0); 3730 } 3731 3732 static int 3733 pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf) 3734 { 3735 /* map each value to the corresponding 2's complement, to 3736 * preserve the timeout value provided with pcap_set_timeout */ 3737 if (nonblock) { 3738 if (p->md.timeout >= 0) { 3739 /* 3740 * Timeout is non-negative, so we're not already 3741 * in non-blocking mode; set it to the 2's 3742 * complement, to make it negative, as an 3743 * indication that we're in non-blocking mode. 3744 */ 3745 p->md.timeout = p->md.timeout*-1 - 1; 3746 } 3747 } else { 3748 if (p->md.timeout < 0) { 3749 /* 3750 * Timeout is negative, so we're not already 3751 * in blocking mode; reverse the previous 3752 * operation, to make the timeout non-negative 3753 * again. 3754 */ 3755 p->md.timeout = (p->md.timeout+1)*-1; 3756 } 3757 } 3758 return 0; 3759 } 3760 3761 static inline union thdr * 3762 pcap_get_ring_frame(pcap_t *handle, int status) 3763 { 3764 union thdr h; 3765 3766 h.raw = RING_GET_FRAME(handle); 3767 switch (handle->md.tp_version) { 3768 case TPACKET_V1: 3769 if (status != (h.h1->tp_status ? TP_STATUS_USER : 3770 TP_STATUS_KERNEL)) 3771 return NULL; 3772 break; 3773 #ifdef HAVE_TPACKET2 3774 case TPACKET_V2: 3775 if (status != (h.h2->tp_status ? TP_STATUS_USER : 3776 TP_STATUS_KERNEL)) 3777 return NULL; 3778 break; 3779 #endif 3780 } 3781 return h.raw; 3782 } 3783 3784 #ifndef POLLRDHUP 3785 #define POLLRDHUP 0 3786 #endif 3787 3788 static int 3789 pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, 3790 u_char *user) 3791 { 3792 int timeout; 3793 int pkts = 0; 3794 char c; 3795 3796 /* wait for frames availability.*/ 3797 if (!pcap_get_ring_frame(handle, TP_STATUS_USER)) { 3798 struct pollfd pollinfo; 3799 int ret; 3800 3801 pollinfo.fd = handle->fd; 3802 pollinfo.events = POLLIN; 3803 3804 if (handle->md.timeout == 0) 3805 timeout = -1; /* block forever */ 3806 else if (handle->md.timeout > 0) 3807 timeout = handle->md.timeout; /* block for that amount of time */ 3808 else 3809 timeout = 0; /* non-blocking mode - poll to pick up errors */ 3810 do { 3811 ret = poll(&pollinfo, 1, timeout); 3812 if (ret < 0 && errno != EINTR) { 3813 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3814 "can't poll on packet socket: %s", 3815 pcap_strerror(errno)); 3816 return PCAP_ERROR; 3817 } else if (ret > 0 && 3818 (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) { 3819 /* 3820 * There's some indication other than 3821 * "you can read on this descriptor" on 3822 * the descriptor. 3823 */ 3824 if (pollinfo.revents & (POLLHUP | POLLRDHUP)) { 3825 snprintf(handle->errbuf, 3826 PCAP_ERRBUF_SIZE, 3827 "Hangup on packet socket"); 3828 return PCAP_ERROR; 3829 } 3830 if (pollinfo.revents & POLLERR) { 3831 /* 3832 * A recv() will give us the 3833 * actual error code. 3834 * 3835 * XXX - make the socket non-blocking? 3836 */ 3837 if (recv(handle->fd, &c, sizeof c, 3838 MSG_PEEK) != -1) 3839 continue; /* what, no error? */ 3840 if (errno == ENETDOWN) { 3841 /* 3842 * The device on which we're 3843 * capturing went away. 3844 * 3845 * XXX - we should really return 3846 * PCAP_ERROR_IFACE_NOT_UP, 3847 * but pcap_dispatch() etc. 3848 * aren't defined to return 3849 * that. 3850 */ 3851 snprintf(handle->errbuf, 3852 PCAP_ERRBUF_SIZE, 3853 "The interface went down"); 3854 } else { 3855 snprintf(handle->errbuf, 3856 PCAP_ERRBUF_SIZE, 3857 "Error condition on packet socket: %s", 3858 strerror(errno)); 3859 } 3860 return PCAP_ERROR; 3861 } 3862 if (pollinfo.revents & POLLNVAL) { 3863 snprintf(handle->errbuf, 3864 PCAP_ERRBUF_SIZE, 3865 "Invalid polling request on packet socket"); 3866 return PCAP_ERROR; 3867 } 3868 } 3869 /* check for break loop condition on interrupted syscall*/ 3870 if (handle->break_loop) { 3871 handle->break_loop = 0; 3872 return PCAP_ERROR_BREAK; 3873 } 3874 } while (ret < 0); 3875 } 3876 3877 /* non-positive values of max_packets are used to require all 3878 * packets currently available in the ring */ 3879 while ((pkts < max_packets) || (max_packets <= 0)) { 3880 int run_bpf; 3881 struct sockaddr_ll *sll; 3882 struct pcap_pkthdr pcaphdr; 3883 unsigned char *bp; 3884 union thdr h; 3885 unsigned int tp_len; 3886 unsigned int tp_mac; 3887 unsigned int tp_snaplen; 3888 unsigned int tp_sec; 3889 unsigned int tp_usec; 3890 3891 h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); 3892 if (!h.raw) 3893 break; 3894 3895 switch (handle->md.tp_version) { 3896 case TPACKET_V1: 3897 tp_len = h.h1->tp_len; 3898 tp_mac = h.h1->tp_mac; 3899 tp_snaplen = h.h1->tp_snaplen; 3900 tp_sec = h.h1->tp_sec; 3901 tp_usec = h.h1->tp_usec; 3902 break; 3903 #ifdef HAVE_TPACKET2 3904 case TPACKET_V2: 3905 tp_len = h.h2->tp_len; 3906 tp_mac = h.h2->tp_mac; 3907 tp_snaplen = h.h2->tp_snaplen; 3908 tp_sec = h.h2->tp_sec; 3909 tp_usec = h.h2->tp_nsec / 1000; 3910 break; 3911 #endif 3912 default: 3913 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3914 "unsupported tpacket version %d", 3915 handle->md.tp_version); 3916 return -1; 3917 } 3918 /* perform sanity check on internal offset. */ 3919 if (tp_mac + tp_snaplen > handle->bufsize) { 3920 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 3921 "corrupted frame on kernel ring mac " 3922 "offset %d + caplen %d > frame len %d", 3923 tp_mac, tp_snaplen, handle->bufsize); 3924 return -1; 3925 } 3926 3927 /* run filter on received packet 3928 * If the kernel filtering is enabled we need to run the 3929 * filter until all the frames present into the ring 3930 * at filter creation time are processed. 3931 * In such case md.use_bpf is used as a counter for the 3932 * packet we need to filter. 3933 * Note: alternatively it could be possible to stop applying 3934 * the filter when the ring became empty, but it can possibly 3935 * happen a lot later... */ 3936 bp = (unsigned char*)h.raw + tp_mac; 3937 run_bpf = (!handle->md.use_bpf) || 3938 ((handle->md.use_bpf>1) && handle->md.use_bpf--); 3939 if (run_bpf && handle->fcode.bf_insns && 3940 (bpf_filter(handle->fcode.bf_insns, bp, 3941 tp_len, tp_snaplen) == 0)) 3942 goto skip; 3943 3944 /* 3945 * Do checks based on packet direction. 3946 */ 3947 sll = (void *)h.raw + TPACKET_ALIGN(handle->md.tp_hdrlen); 3948 if (sll->sll_pkttype == PACKET_OUTGOING) { 3949 /* 3950 * Outgoing packet. 3951 * If this is from the loopback device, reject it; 3952 * we'll see the packet as an incoming packet as well, 3953 * and we don't want to see it twice. 3954 */ 3955 if (sll->sll_ifindex == handle->md.lo_ifindex) 3956 goto skip; 3957 3958 /* 3959 * If the user only wants incoming packets, reject it. 3960 */ 3961 if (handle->direction == PCAP_D_IN) 3962 goto skip; 3963 } else { 3964 /* 3965 * Incoming packet. 3966 * If the user only wants outgoing packets, reject it. 3967 */ 3968 if (handle->direction == PCAP_D_OUT) 3969 goto skip; 3970 } 3971 3972 /* get required packet info from ring header */ 3973 pcaphdr.ts.tv_sec = tp_sec; 3974 pcaphdr.ts.tv_usec = tp_usec; 3975 pcaphdr.caplen = tp_snaplen; 3976 pcaphdr.len = tp_len; 3977 3978 /* if required build in place the sll header*/ 3979 if (handle->md.cooked) { 3980 struct sll_header *hdrp; 3981 3982 /* 3983 * The kernel should have left us with enough 3984 * space for an sll header; back up the packet 3985 * data pointer into that space, as that'll be 3986 * the beginning of the packet we pass to the 3987 * callback. 3988 */ 3989 bp -= SLL_HDR_LEN; 3990 3991 /* 3992 * Let's make sure that's past the end of 3993 * the tpacket header, i.e. >= 3994 * ((u_char *)thdr + TPACKET_HDRLEN), so we 3995 * don't step on the header when we construct 3996 * the sll header. 3997 */ 3998 if (bp < (u_char *)h.raw + 3999 TPACKET_ALIGN(handle->md.tp_hdrlen) + 4000 sizeof(struct sockaddr_ll)) { 4001 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4002 "cooked-mode frame doesn't have room for sll header"); 4003 return -1; 4004 } 4005 4006 /* 4007 * OK, that worked; construct the sll header. 4008 */ 4009 hdrp = (struct sll_header *)bp; 4010 hdrp->sll_pkttype = map_packet_type_to_sll_type( 4011 sll->sll_pkttype); 4012 hdrp->sll_hatype = htons(sll->sll_hatype); 4013 hdrp->sll_halen = htons(sll->sll_halen); 4014 memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN); 4015 hdrp->sll_protocol = sll->sll_protocol; 4016 4017 /* update packet len */ 4018 pcaphdr.caplen += SLL_HDR_LEN; 4019 pcaphdr.len += SLL_HDR_LEN; 4020 } 4021 4022 #ifdef HAVE_TPACKET2 4023 if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci && 4024 tp_snaplen >= 2 * ETH_ALEN) { 4025 struct vlan_tag *tag; 4026 4027 bp -= VLAN_TAG_LEN; 4028 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN); 4029 4030 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN); 4031 tag->vlan_tpid = htons(ETH_P_8021Q); 4032 tag->vlan_tci = htons(h.h2->tp_vlan_tci); 4033 4034 pcaphdr.caplen += VLAN_TAG_LEN; 4035 pcaphdr.len += VLAN_TAG_LEN; 4036 } 4037 #endif 4038 4039 /* 4040 * The only way to tell the kernel to cut off the 4041 * packet at a snapshot length is with a filter program; 4042 * if there's no filter program, the kernel won't cut 4043 * the packet off. 4044 * 4045 * Trim the snapshot length to be no longer than the 4046 * specified snapshot length. 4047 */ 4048 if (pcaphdr.caplen > handle->snapshot) 4049 pcaphdr.caplen = handle->snapshot; 4050 4051 /* pass the packet to the user */ 4052 pkts++; 4053 callback(user, &pcaphdr, bp); 4054 handle->md.packets_read++; 4055 4056 skip: 4057 /* next packet */ 4058 switch (handle->md.tp_version) { 4059 case TPACKET_V1: 4060 h.h1->tp_status = TP_STATUS_KERNEL; 4061 break; 4062 #ifdef HAVE_TPACKET2 4063 case TPACKET_V2: 4064 h.h2->tp_status = TP_STATUS_KERNEL; 4065 break; 4066 #endif 4067 } 4068 if (++handle->offset >= handle->cc) 4069 handle->offset = 0; 4070 4071 /* check for break loop condition*/ 4072 if (handle->break_loop) { 4073 handle->break_loop = 0; 4074 return PCAP_ERROR_BREAK; 4075 } 4076 } 4077 return pkts; 4078 } 4079 4080 static int 4081 pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) 4082 { 4083 int n, offset; 4084 int ret; 4085 4086 /* 4087 * Don't rewrite "ret" instructions; we don't need to, as 4088 * we're not reading packets with recvmsg(), and we don't 4089 * want to, as, by not rewriting them, the kernel can avoid 4090 * copying extra data. 4091 */ 4092 ret = pcap_setfilter_linux_common(handle, filter, 1); 4093 if (ret < 0) 4094 return ret; 4095 4096 /* if the kernel filter is enabled, we need to apply the filter on 4097 * all packets present into the ring. Get an upper bound of their number 4098 */ 4099 if (!handle->md.use_bpf) 4100 return ret; 4101 4102 /* walk the ring backward and count the free slot */ 4103 offset = handle->offset; 4104 if (--handle->offset < 0) 4105 handle->offset = handle->cc - 1; 4106 for (n=0; n < handle->cc; ++n) { 4107 if (--handle->offset < 0) 4108 handle->offset = handle->cc - 1; 4109 if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL)) 4110 break; 4111 } 4112 4113 /* be careful to not change current ring position */ 4114 handle->offset = offset; 4115 4116 /* store the number of packets currently present in the ring */ 4117 handle->md.use_bpf = 1 + (handle->cc - n); 4118 return ret; 4119 } 4120 4121 #endif /* HAVE_PACKET_RING */ 4122 4123 4124 #ifdef HAVE_PF_PACKET_SOCKETS 4125 /* 4126 * Return the index of the given device name. Fill ebuf and return 4127 * -1 on failure. 4128 */ 4129 static int 4130 iface_get_id(int fd, const char *device, char *ebuf) 4131 { 4132 struct ifreq ifr; 4133 4134 memset(&ifr, 0, sizeof(ifr)); 4135 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 4136 4137 if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { 4138 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4139 "SIOCGIFINDEX: %s", pcap_strerror(errno)); 4140 return -1; 4141 } 4142 4143 return ifr.ifr_ifindex; 4144 } 4145 4146 /* 4147 * Bind the socket associated with FD to the given device. 4148 * Return 1 on success, 0 if we should try a SOCK_PACKET socket, 4149 * or a PCAP_ERROR_ value on a hard error. 4150 */ 4151 static int 4152 iface_bind(int fd, int ifindex, char *ebuf) 4153 { 4154 struct sockaddr_ll sll; 4155 int err; 4156 socklen_t errlen = sizeof(err); 4157 4158 memset(&sll, 0, sizeof(sll)); 4159 sll.sll_family = AF_PACKET; 4160 sll.sll_ifindex = ifindex; 4161 sll.sll_protocol = htons(ETH_P_ALL); 4162 4163 if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) { 4164 if (errno == ENETDOWN) { 4165 /* 4166 * Return a "network down" indication, so that 4167 * the application can report that rather than 4168 * saying we had a mysterious failure and 4169 * suggest that they report a problem to the 4170 * libpcap developers. 4171 */ 4172 return PCAP_ERROR_IFACE_NOT_UP; 4173 } else { 4174 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4175 "bind: %s", pcap_strerror(errno)); 4176 return PCAP_ERROR; 4177 } 4178 } 4179 4180 /* Any pending errors, e.g., network is down? */ 4181 4182 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { 4183 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4184 "getsockopt: %s", pcap_strerror(errno)); 4185 return 0; 4186 } 4187 4188 if (err == ENETDOWN) { 4189 /* 4190 * Return a "network down" indication, so that 4191 * the application can report that rather than 4192 * saying we had a mysterious failure and 4193 * suggest that they report a problem to the 4194 * libpcap developers. 4195 */ 4196 return PCAP_ERROR_IFACE_NOT_UP; 4197 } else if (err > 0) { 4198 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4199 "bind: %s", pcap_strerror(err)); 4200 return 0; 4201 } 4202 4203 return 1; 4204 } 4205 4206 #ifdef IW_MODE_MONITOR 4207 /* 4208 * Check whether the device supports the Wireless Extensions. 4209 * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE 4210 * if the device doesn't even exist. 4211 */ 4212 static int 4213 has_wext(int sock_fd, const char *device, char *ebuf) 4214 { 4215 struct iwreq ireq; 4216 4217 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4218 sizeof ireq.ifr_ifrn.ifrn_name); 4219 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4220 if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0) 4221 return 1; /* yes */ 4222 snprintf(ebuf, PCAP_ERRBUF_SIZE, 4223 "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); 4224 if (errno == ENODEV) 4225 return PCAP_ERROR_NO_SUCH_DEVICE; 4226 return 0; 4227 } 4228 4229 /* 4230 * Per me si va ne la citta dolente, 4231 * Per me si va ne l'etterno dolore, 4232 * ... 4233 * Lasciate ogne speranza, voi ch'intrate. 4234 * 4235 * XXX - airmon-ng does special stuff with the Orinoco driver and the 4236 * wlan-ng driver. 4237 */ 4238 typedef enum { 4239 MONITOR_WEXT, 4240 MONITOR_HOSTAP, 4241 MONITOR_PRISM, 4242 MONITOR_PRISM54, 4243 MONITOR_ACX100, 4244 MONITOR_RT2500, 4245 MONITOR_RT2570, 4246 MONITOR_RT73, 4247 MONITOR_RTL8XXX 4248 } monitor_type; 4249 4250 /* 4251 * Use the Wireless Extensions, if we have them, to try to turn monitor mode 4252 * on if it's not already on. 4253 * 4254 * Returns 1 on success, 0 if we don't support the Wireless Extensions 4255 * on this device, or a PCAP_ERROR_ value if we do support them but 4256 * we weren't able to turn monitor mode on. 4257 */ 4258 static int 4259 enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) 4260 { 4261 /* 4262 * XXX - at least some adapters require non-Wireless Extensions 4263 * mechanisms to turn monitor mode on. 4264 * 4265 * Atheros cards might require that a separate "monitor virtual access 4266 * point" be created, with later versions of the madwifi driver. 4267 * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode 4268 * monitor -bssid", which apparently spits out a line "athN" 4269 * where "athN" is the monitor mode device. To leave monitor 4270 * mode, it destroys the monitor mode device. 4271 * 4272 * Some Intel Centrino adapters might require private ioctls to get 4273 * radio headers; the ipw2200 and ipw3945 drivers allow you to 4274 * configure a separate "rtapN" interface to capture in monitor 4275 * mode without preventing the adapter from operating normally. 4276 * (airmon-ng doesn't appear to use that, though.) 4277 * 4278 * It would be Truly Wonderful if mac80211 and nl80211 cleaned this 4279 * up, and if all drivers were converted to mac80211 drivers. 4280 * 4281 * If interface {if} is a mac80211 driver, the file 4282 * /sys/class/net/{if}/phy80211 is a symlink to 4283 * /sys/class/ieee80211/{phydev}, for some {phydev}. 4284 * 4285 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at 4286 * least, has a "wmaster0" device and a "wlan0" device; the 4287 * latter is the one with the IP address. Both show up in 4288 * "tcpdump -D" output. Capturing on the wmaster0 device 4289 * captures with 802.11 headers. 4290 * 4291 * airmon-ng searches through /sys/class/net for devices named 4292 * monN, starting with mon0; as soon as one *doesn't* exist, 4293 * it chooses that as the monitor device name. If the "iw" 4294 * command exists, it does "iw dev {if} interface add {monif} 4295 * type monitor", where {monif} is the monitor device. It 4296 * then (sigh) sleeps .1 second, and then configures the 4297 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface 4298 * is a file, it writes {mondev}, without a newline, to that file, 4299 * and again (sigh) sleeps .1 second, and then iwconfig's that 4300 * device into monitor mode and configures it up. Otherwise, 4301 * you can't do monitor mode. 4302 * 4303 * All these devices are "glued" together by having the 4304 * /sys/class/net/{device}/phy80211 links pointing to the same 4305 * place, so, given a wmaster, wlan, or mon device, you can 4306 * find the other devices by looking for devices with 4307 * the same phy80211 link. 4308 * 4309 * To turn monitor mode off, delete the monitor interface, 4310 * either with "iw dev {monif} interface del" or by sending 4311 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface 4312 * 4313 * Note: if you try to create a monitor device named "monN", and 4314 * there's already a "monN" device, it fails, as least with 4315 * the netlink interface (which is what iw uses), with a return 4316 * value of -ENFILE. (Return values are negative errnos.) We 4317 * could probably use that to find an unused device. 4318 */ 4319 int err; 4320 struct iwreq ireq; 4321 struct iw_priv_args *priv; 4322 monitor_type montype; 4323 int i; 4324 __u32 cmd; 4325 struct ifreq ifr; 4326 int oldflags; 4327 int args[2]; 4328 int channel; 4329 4330 /* 4331 * Does this device *support* the Wireless Extensions? 4332 */ 4333 err = has_wext(sock_fd, device, handle->errbuf); 4334 if (err <= 0) 4335 return err; /* either it doesn't or the device doesn't even exist */ 4336 /* 4337 * Start out assuming we have no private extensions to control 4338 * radio metadata. 4339 */ 4340 montype = MONITOR_WEXT; 4341 cmd = 0; 4342 4343 /* 4344 * Try to get all the Wireless Extensions private ioctls 4345 * supported by this device. 4346 * 4347 * First, get the size of the buffer we need, by supplying no 4348 * buffer and a length of 0. If the device supports private 4349 * ioctls, it should return E2BIG, with ireq.u.data.length set 4350 * to the length we need. If it doesn't support them, it should 4351 * return EOPNOTSUPP. 4352 */ 4353 memset(&ireq, 0, sizeof ireq); 4354 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4355 sizeof ireq.ifr_ifrn.ifrn_name); 4356 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4357 ireq.u.data.pointer = (void *)args; 4358 ireq.u.data.length = 0; 4359 ireq.u.data.flags = 0; 4360 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { 4361 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4362 "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!", 4363 device); 4364 return PCAP_ERROR; 4365 } 4366 if (errno != EOPNOTSUPP) { 4367 /* 4368 * OK, it's not as if there are no private ioctls. 4369 */ 4370 if (errno != E2BIG) { 4371 /* 4372 * Failed. 4373 */ 4374 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4375 "%s: SIOCGIWPRIV: %s", device, 4376 pcap_strerror(errno)); 4377 return PCAP_ERROR; 4378 } 4379 4380 /* 4381 * OK, try to get the list of private ioctls. 4382 */ 4383 priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args)); 4384 if (priv == NULL) { 4385 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4386 "malloc: %s", pcap_strerror(errno)); 4387 return PCAP_ERROR; 4388 } 4389 ireq.u.data.pointer = (void *)priv; 4390 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { 4391 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4392 "%s: SIOCGIWPRIV: %s", device, 4393 pcap_strerror(errno)); 4394 free(priv); 4395 return PCAP_ERROR; 4396 } 4397 4398 /* 4399 * Look for private ioctls to turn monitor mode on or, if 4400 * monitor mode is on, to set the header type. 4401 */ 4402 for (i = 0; i < ireq.u.data.length; i++) { 4403 if (strcmp(priv[i].name, "monitor_type") == 0) { 4404 /* 4405 * Hostap driver, use this one. 4406 * Set monitor mode first. 4407 * You can set it to 0 to get DLT_IEEE80211, 4408 * 1 to get DLT_PRISM, 2 to get 4409 * DLT_IEEE80211_RADIO_AVS, and, with more 4410 * recent versions of the driver, 3 to get 4411 * DLT_IEEE80211_RADIO. 4412 */ 4413 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4414 break; 4415 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4416 break; 4417 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4418 break; 4419 montype = MONITOR_HOSTAP; 4420 cmd = priv[i].cmd; 4421 break; 4422 } 4423 if (strcmp(priv[i].name, "set_prismhdr") == 0) { 4424 /* 4425 * Prism54 driver, use this one. 4426 * Set monitor mode first. 4427 * You can set it to 2 to get DLT_IEEE80211 4428 * or 3 or get DLT_PRISM. 4429 */ 4430 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4431 break; 4432 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4433 break; 4434 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4435 break; 4436 montype = MONITOR_PRISM54; 4437 cmd = priv[i].cmd; 4438 break; 4439 } 4440 if (strcmp(priv[i].name, "forceprismheader") == 0) { 4441 /* 4442 * RT2570 driver, use this one. 4443 * Do this after turning monitor mode on. 4444 * You can set it to 1 to get DLT_PRISM or 2 4445 * to get DLT_IEEE80211. 4446 */ 4447 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4448 break; 4449 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4450 break; 4451 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4452 break; 4453 montype = MONITOR_RT2570; 4454 cmd = priv[i].cmd; 4455 break; 4456 } 4457 if (strcmp(priv[i].name, "forceprism") == 0) { 4458 /* 4459 * RT73 driver, use this one. 4460 * Do this after turning monitor mode on. 4461 * Its argument is a *string*; you can 4462 * set it to "1" to get DLT_PRISM or "2" 4463 * to get DLT_IEEE80211. 4464 */ 4465 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR) 4466 break; 4467 if (priv[i].set_args & IW_PRIV_SIZE_FIXED) 4468 break; 4469 montype = MONITOR_RT73; 4470 cmd = priv[i].cmd; 4471 break; 4472 } 4473 if (strcmp(priv[i].name, "prismhdr") == 0) { 4474 /* 4475 * One of the RTL8xxx drivers, use this one. 4476 * It can only be done after monitor mode 4477 * has been turned on. You can set it to 1 4478 * to get DLT_PRISM or 0 to get DLT_IEEE80211. 4479 */ 4480 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4481 break; 4482 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4483 break; 4484 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) 4485 break; 4486 montype = MONITOR_RTL8XXX; 4487 cmd = priv[i].cmd; 4488 break; 4489 } 4490 if (strcmp(priv[i].name, "rfmontx") == 0) { 4491 /* 4492 * RT2500 or RT61 driver, use this one. 4493 * It has one one-byte parameter; set 4494 * u.data.length to 1 and u.data.pointer to 4495 * point to the parameter. 4496 * It doesn't itself turn monitor mode on. 4497 * You can set it to 1 to allow transmitting 4498 * in monitor mode(?) and get DLT_IEEE80211, 4499 * or set it to 0 to disallow transmitting in 4500 * monitor mode(?) and get DLT_PRISM. 4501 */ 4502 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4503 break; 4504 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2) 4505 break; 4506 montype = MONITOR_RT2500; 4507 cmd = priv[i].cmd; 4508 break; 4509 } 4510 if (strcmp(priv[i].name, "monitor") == 0) { 4511 /* 4512 * Either ACX100 or hostap, use this one. 4513 * It turns monitor mode on. 4514 * If it takes two arguments, it's ACX100; 4515 * the first argument is 1 for DLT_PRISM 4516 * or 2 for DLT_IEEE80211, and the second 4517 * argument is the channel on which to 4518 * run. If it takes one argument, it's 4519 * HostAP, and the argument is 2 for 4520 * DLT_IEEE80211 and 3 for DLT_PRISM. 4521 * 4522 * If we see this, we don't quit, as this 4523 * might be a version of the hostap driver 4524 * that also supports "monitor_type". 4525 */ 4526 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) 4527 break; 4528 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) 4529 break; 4530 switch (priv[i].set_args & IW_PRIV_SIZE_MASK) { 4531 4532 case 1: 4533 montype = MONITOR_PRISM; 4534 cmd = priv[i].cmd; 4535 break; 4536 4537 case 2: 4538 montype = MONITOR_ACX100; 4539 cmd = priv[i].cmd; 4540 break; 4541 4542 default: 4543 break; 4544 } 4545 } 4546 } 4547 free(priv); 4548 } 4549 4550 /* 4551 * XXX - ipw3945? islism? 4552 */ 4553 4554 /* 4555 * Get the old mode. 4556 */ 4557 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4558 sizeof ireq.ifr_ifrn.ifrn_name); 4559 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4560 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) { 4561 /* 4562 * We probably won't be able to set the mode, either. 4563 */ 4564 return PCAP_ERROR_RFMON_NOTSUP; 4565 } 4566 4567 /* 4568 * Is it currently in monitor mode? 4569 */ 4570 if (ireq.u.mode == IW_MODE_MONITOR) { 4571 /* 4572 * Yes. Just leave things as they are. 4573 * We don't offer multiple link-layer types, as 4574 * changing the link-layer type out from under 4575 * somebody else capturing in monitor mode would 4576 * be considered rude. 4577 */ 4578 return 1; 4579 } 4580 /* 4581 * No. We have to put the adapter into rfmon mode. 4582 */ 4583 4584 /* 4585 * If we haven't already done so, arrange to have 4586 * "pcap_close_all()" called when we exit. 4587 */ 4588 if (!pcap_do_addexit(handle)) { 4589 /* 4590 * "atexit()" failed; don't put the interface 4591 * in rfmon mode, just give up. 4592 */ 4593 return PCAP_ERROR_RFMON_NOTSUP; 4594 } 4595 4596 /* 4597 * Save the old mode. 4598 */ 4599 handle->md.oldmode = ireq.u.mode; 4600 4601 /* 4602 * Put the adapter in rfmon mode. How we do this depends 4603 * on whether we have a special private ioctl or not. 4604 */ 4605 if (montype == MONITOR_PRISM) { 4606 /* 4607 * We have the "monitor" private ioctl, but none of 4608 * the other private ioctls. Use this, and select 4609 * the Prism header. 4610 * 4611 * If it fails, just fall back on SIOCSIWMODE. 4612 */ 4613 memset(&ireq, 0, sizeof ireq); 4614 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4615 sizeof ireq.ifr_ifrn.ifrn_name); 4616 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4617 ireq.u.data.length = 1; /* 1 argument */ 4618 args[0] = 3; /* request Prism header */ 4619 memcpy(ireq.u.name, args, IFNAMSIZ); 4620 if (ioctl(sock_fd, cmd, &ireq) != -1) { 4621 /* 4622 * Success. 4623 * Note that we have to put the old mode back 4624 * when we close the device. 4625 */ 4626 handle->md.must_do_on_close |= MUST_CLEAR_RFMON; 4627 4628 /* 4629 * Add this to the list of pcaps to close 4630 * when we exit. 4631 */ 4632 pcap_add_to_pcaps_to_close(handle); 4633 4634 return 1; 4635 } 4636 4637 /* 4638 * Failure. Fall back on SIOCSIWMODE. 4639 */ 4640 } 4641 4642 /* 4643 * First, take the interface down if it's up; otherwise, we 4644 * might get EBUSY. 4645 */ 4646 memset(&ifr, 0, sizeof(ifr)); 4647 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 4648 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { 4649 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4650 "%s: Can't get flags: %s", device, strerror(errno)); 4651 return PCAP_ERROR; 4652 } 4653 oldflags = 0; 4654 if (ifr.ifr_flags & IFF_UP) { 4655 oldflags = ifr.ifr_flags; 4656 ifr.ifr_flags &= ~IFF_UP; 4657 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4658 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4659 "%s: Can't set flags: %s", device, strerror(errno)); 4660 return PCAP_ERROR; 4661 } 4662 } 4663 4664 /* 4665 * Then turn monitor mode on. 4666 */ 4667 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4668 sizeof ireq.ifr_ifrn.ifrn_name); 4669 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4670 ireq.u.mode = IW_MODE_MONITOR; 4671 if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) { 4672 /* 4673 * Scientist, you've failed. 4674 * Bring the interface back up if we shut it down. 4675 */ 4676 ifr.ifr_flags = oldflags; 4677 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4678 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4679 "%s: Can't set flags: %s", device, strerror(errno)); 4680 return PCAP_ERROR; 4681 } 4682 return PCAP_ERROR_RFMON_NOTSUP; 4683 } 4684 4685 /* 4686 * XXX - airmon-ng does "iwconfig {if} key off" after setting 4687 * monitor mode and setting the channel, and then does 4688 * "iwconfig up". 4689 */ 4690 4691 /* 4692 * Now select the appropriate radio header. 4693 */ 4694 switch (montype) { 4695 4696 case MONITOR_WEXT: 4697 /* 4698 * We don't have any private ioctl to set the header. 4699 */ 4700 break; 4701 4702 case MONITOR_HOSTAP: 4703 /* 4704 * Try to select the radiotap header. 4705 */ 4706 memset(&ireq, 0, sizeof ireq); 4707 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4708 sizeof ireq.ifr_ifrn.ifrn_name); 4709 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4710 args[0] = 3; /* request radiotap header */ 4711 memcpy(ireq.u.name, args, sizeof (int)); 4712 if (ioctl(sock_fd, cmd, &ireq) != -1) 4713 break; /* success */ 4714 4715 /* 4716 * That failed. Try to select the AVS header. 4717 */ 4718 memset(&ireq, 0, sizeof ireq); 4719 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4720 sizeof ireq.ifr_ifrn.ifrn_name); 4721 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4722 args[0] = 2; /* request AVS header */ 4723 memcpy(ireq.u.name, args, sizeof (int)); 4724 if (ioctl(sock_fd, cmd, &ireq) != -1) 4725 break; /* success */ 4726 4727 /* 4728 * That failed. Try to select the Prism header. 4729 */ 4730 memset(&ireq, 0, sizeof ireq); 4731 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4732 sizeof ireq.ifr_ifrn.ifrn_name); 4733 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4734 args[0] = 1; /* request Prism header */ 4735 memcpy(ireq.u.name, args, sizeof (int)); 4736 ioctl(sock_fd, cmd, &ireq); 4737 break; 4738 4739 case MONITOR_PRISM: 4740 /* 4741 * The private ioctl failed. 4742 */ 4743 break; 4744 4745 case MONITOR_PRISM54: 4746 /* 4747 * Select the Prism header. 4748 */ 4749 memset(&ireq, 0, sizeof ireq); 4750 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4751 sizeof ireq.ifr_ifrn.ifrn_name); 4752 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4753 args[0] = 3; /* request Prism header */ 4754 memcpy(ireq.u.name, args, sizeof (int)); 4755 ioctl(sock_fd, cmd, &ireq); 4756 break; 4757 4758 case MONITOR_ACX100: 4759 /* 4760 * Get the current channel. 4761 */ 4762 memset(&ireq, 0, sizeof ireq); 4763 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4764 sizeof ireq.ifr_ifrn.ifrn_name); 4765 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4766 if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) { 4767 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4768 "%s: SIOCGIWFREQ: %s", device, 4769 pcap_strerror(errno)); 4770 return PCAP_ERROR; 4771 } 4772 channel = ireq.u.freq.m; 4773 4774 /* 4775 * Select the Prism header, and set the channel to the 4776 * current value. 4777 */ 4778 memset(&ireq, 0, sizeof ireq); 4779 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4780 sizeof ireq.ifr_ifrn.ifrn_name); 4781 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4782 args[0] = 1; /* request Prism header */ 4783 args[1] = channel; /* set channel */ 4784 memcpy(ireq.u.name, args, 2*sizeof (int)); 4785 ioctl(sock_fd, cmd, &ireq); 4786 break; 4787 4788 case MONITOR_RT2500: 4789 /* 4790 * Disallow transmission - that turns on the 4791 * Prism header. 4792 */ 4793 memset(&ireq, 0, sizeof ireq); 4794 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4795 sizeof ireq.ifr_ifrn.ifrn_name); 4796 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4797 args[0] = 0; /* disallow transmitting */ 4798 memcpy(ireq.u.name, args, sizeof (int)); 4799 ioctl(sock_fd, cmd, &ireq); 4800 break; 4801 4802 case MONITOR_RT2570: 4803 /* 4804 * Force the Prism header. 4805 */ 4806 memset(&ireq, 0, sizeof ireq); 4807 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4808 sizeof ireq.ifr_ifrn.ifrn_name); 4809 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4810 args[0] = 1; /* request Prism header */ 4811 memcpy(ireq.u.name, args, sizeof (int)); 4812 ioctl(sock_fd, cmd, &ireq); 4813 break; 4814 4815 case MONITOR_RT73: 4816 /* 4817 * Force the Prism header. 4818 */ 4819 memset(&ireq, 0, sizeof ireq); 4820 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4821 sizeof ireq.ifr_ifrn.ifrn_name); 4822 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4823 ireq.u.data.length = 1; /* 1 argument */ 4824 ireq.u.data.pointer = "1"; 4825 ireq.u.data.flags = 0; 4826 ioctl(sock_fd, cmd, &ireq); 4827 break; 4828 4829 case MONITOR_RTL8XXX: 4830 /* 4831 * Force the Prism header. 4832 */ 4833 memset(&ireq, 0, sizeof ireq); 4834 strncpy(ireq.ifr_ifrn.ifrn_name, device, 4835 sizeof ireq.ifr_ifrn.ifrn_name); 4836 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; 4837 args[0] = 1; /* request Prism header */ 4838 memcpy(ireq.u.name, args, sizeof (int)); 4839 ioctl(sock_fd, cmd, &ireq); 4840 break; 4841 } 4842 4843 /* 4844 * Now bring the interface back up if we brought it down. 4845 */ 4846 if (oldflags != 0) { 4847 ifr.ifr_flags = oldflags; 4848 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { 4849 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4850 "%s: Can't set flags: %s", device, strerror(errno)); 4851 4852 /* 4853 * At least try to restore the old mode on the 4854 * interface. 4855 */ 4856 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { 4857 /* 4858 * Scientist, you've failed. 4859 */ 4860 fprintf(stderr, 4861 "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n" 4862 "Please adjust manually.\n", 4863 strerror(errno)); 4864 } 4865 return PCAP_ERROR; 4866 } 4867 } 4868 4869 /* 4870 * Note that we have to put the old mode back when we 4871 * close the device. 4872 */ 4873 handle->md.must_do_on_close |= MUST_CLEAR_RFMON; 4874 4875 /* 4876 * Add this to the list of pcaps to close when we exit. 4877 */ 4878 pcap_add_to_pcaps_to_close(handle); 4879 4880 return 1; 4881 } 4882 #endif /* IW_MODE_MONITOR */ 4883 4884 /* 4885 * Try various mechanisms to enter monitor mode. 4886 */ 4887 static int 4888 enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) 4889 { 4890 #if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) 4891 int ret; 4892 #endif 4893 4894 #ifdef HAVE_LIBNL 4895 ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); 4896 if (ret < 0) 4897 return ret; /* error attempting to do so */ 4898 if (ret == 1) 4899 return 1; /* success */ 4900 #endif /* HAVE_LIBNL */ 4901 4902 #ifdef IW_MODE_MONITOR 4903 ret = enter_rfmon_mode_wext(handle, sock_fd, device); 4904 if (ret < 0) 4905 return ret; /* error attempting to do so */ 4906 if (ret == 1) 4907 return 1; /* success */ 4908 #endif /* IW_MODE_MONITOR */ 4909 4910 /* 4911 * Either none of the mechanisms we know about work or none 4912 * of those mechanisms are available, so we can't do monitor 4913 * mode. 4914 */ 4915 return 0; 4916 } 4917 4918 /* 4919 * Find out if we have any form of fragmentation/reassembly offloading. 4920 * 4921 * We do so using SIOCETHTOOL checking for various types of offloading; 4922 * if SIOCETHTOOL isn't defined, or we don't have any #defines for any 4923 * of the types of offloading, there's nothing we can do to check, so 4924 * we just say "no, we don't". 4925 */ 4926 #if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO)) 4927 static int 4928 iface_ethtool_ioctl(pcap_t *handle, int cmd, const char *cmdname) 4929 { 4930 struct ifreq ifr; 4931 struct ethtool_value eval; 4932 4933 memset(&ifr, 0, sizeof(ifr)); 4934 strncpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name)); 4935 eval.cmd = cmd; 4936 ifr.ifr_data = (caddr_t)&eval; 4937 if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) { 4938 if (errno == EOPNOTSUPP) { 4939 /* 4940 * OK, let's just return 0, which, in our 4941 * case, either means "no, what we're asking 4942 * about is not enabled" or "all the flags 4943 * are clear (i.e., nothing is enabled)". 4944 */ 4945 return 0; 4946 } 4947 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 4948 "%s: SIOETHTOOL(%s) ioctl failed: %s", handle->opt.source, 4949 cmdname, strerror(errno)); 4950 return -1; 4951 } 4952 return eval.data; 4953 } 4954 4955 static int 4956 iface_get_offload(pcap_t *handle) 4957 { 4958 int ret; 4959 4960 #ifdef ETHTOOL_GTSO 4961 ret = iface_ethtool_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO"); 4962 if (ret == -1) 4963 return -1; 4964 if (ret) 4965 return 1; /* TCP segmentation offloading on */ 4966 #endif 4967 4968 #ifdef ETHTOOL_GUFO 4969 ret = iface_ethtool_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO"); 4970 if (ret == -1) 4971 return -1; 4972 if (ret) 4973 return 1; /* UDP fragmentation offloading on */ 4974 #endif 4975 4976 #ifdef ETHTOOL_GGSO 4977 /* 4978 * XXX - will this cause large unsegmented packets to be 4979 * handed to PF_PACKET sockets on transmission? If not, 4980 * this need not be checked. 4981 */ 4982 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO"); 4983 if (ret == -1) 4984 return -1; 4985 if (ret) 4986 return 1; /* generic segmentation offloading on */ 4987 #endif 4988 4989 #ifdef ETHTOOL_GFLAGS 4990 ret = iface_ethtool_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS"); 4991 if (ret == -1) 4992 return -1; 4993 if (ret & ETH_FLAG_LRO) 4994 return 1; /* large receive offloading on */ 4995 #endif 4996 4997 #ifdef ETHTOOL_GGRO 4998 /* 4999 * XXX - will this cause large reassembled packets to be 5000 * handed to PF_PACKET sockets on receipt? If not, 5001 * this need not be checked. 5002 */ 5003 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO"); 5004 if (ret == -1) 5005 return -1; 5006 if (ret) 5007 return 1; /* generic (large) receive offloading on */ 5008 #endif 5009 5010 return 0; 5011 } 5012 #else /* SIOCETHTOOL */ 5013 static int 5014 iface_get_offload(pcap_t *handle _U_) 5015 { 5016 /* 5017 * XXX - do we need to get this information if we don't 5018 * have the ethtool ioctls? If so, how do we do that? 5019 */ 5020 return 0; 5021 } 5022 #endif /* SIOCETHTOOL */ 5023 5024 #endif /* HAVE_PF_PACKET_SOCKETS */ 5025 5026 /* ===== Functions to interface to the older kernels ================== */ 5027 5028 /* 5029 * Try to open a packet socket using the old kernel interface. 5030 * Returns 1 on success and a PCAP_ERROR_ value on an error. 5031 */ 5032 static int 5033 activate_old(pcap_t *handle) 5034 { 5035 int arptype; 5036 struct ifreq ifr; 5037 const char *device = handle->opt.source; 5038 struct utsname utsname; 5039 int mtu; 5040 5041 /* Open the socket */ 5042 5043 handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); 5044 if (handle->fd == -1) { 5045 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5046 "socket: %s", pcap_strerror(errno)); 5047 if (errno == EPERM || errno == EACCES) { 5048 /* 5049 * You don't have permission to open the 5050 * socket. 5051 */ 5052 return PCAP_ERROR_PERM_DENIED; 5053 } else { 5054 /* 5055 * Other error. 5056 */ 5057 return PCAP_ERROR; 5058 } 5059 } 5060 5061 /* It worked - we are using the old interface */ 5062 handle->md.sock_packet = 1; 5063 5064 /* ...which means we get the link-layer header. */ 5065 handle->md.cooked = 0; 5066 5067 /* Bind to the given device */ 5068 5069 if (strcmp(device, "any") == 0) { 5070 strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems", 5071 PCAP_ERRBUF_SIZE); 5072 return PCAP_ERROR; 5073 } 5074 if (iface_bind_old(handle->fd, device, handle->errbuf) == -1) 5075 return PCAP_ERROR; 5076 5077 /* 5078 * Try to get the link-layer type. 5079 */ 5080 arptype = iface_get_arptype(handle->fd, device, handle->errbuf); 5081 if (arptype < 0) 5082 return PCAP_ERROR; 5083 5084 /* 5085 * Try to find the DLT_ type corresponding to that 5086 * link-layer type. 5087 */ 5088 map_arphrd_to_dlt(handle, arptype, 0); 5089 if (handle->linktype == -1) { 5090 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5091 "unknown arptype %d", arptype); 5092 return PCAP_ERROR; 5093 } 5094 5095 /* Go to promisc mode if requested */ 5096 5097 if (handle->opt.promisc) { 5098 memset(&ifr, 0, sizeof(ifr)); 5099 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5100 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { 5101 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5102 "SIOCGIFFLAGS: %s", pcap_strerror(errno)); 5103 return PCAP_ERROR; 5104 } 5105 if ((ifr.ifr_flags & IFF_PROMISC) == 0) { 5106 /* 5107 * Promiscuous mode isn't currently on, 5108 * so turn it on, and remember that 5109 * we should turn it off when the 5110 * pcap_t is closed. 5111 */ 5112 5113 /* 5114 * If we haven't already done so, arrange 5115 * to have "pcap_close_all()" called when 5116 * we exit. 5117 */ 5118 if (!pcap_do_addexit(handle)) { 5119 /* 5120 * "atexit()" failed; don't put 5121 * the interface in promiscuous 5122 * mode, just give up. 5123 */ 5124 return PCAP_ERROR; 5125 } 5126 5127 ifr.ifr_flags |= IFF_PROMISC; 5128 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { 5129 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5130 "SIOCSIFFLAGS: %s", 5131 pcap_strerror(errno)); 5132 return PCAP_ERROR; 5133 } 5134 handle->md.must_do_on_close |= MUST_CLEAR_PROMISC; 5135 5136 /* 5137 * Add this to the list of pcaps 5138 * to close when we exit. 5139 */ 5140 pcap_add_to_pcaps_to_close(handle); 5141 } 5142 } 5143 5144 /* 5145 * Compute the buffer size. 5146 * 5147 * We're using SOCK_PACKET, so this might be a 2.0[.x] 5148 * kernel, and might require special handling - check. 5149 */ 5150 if (uname(&utsname) < 0 || 5151 strncmp(utsname.release, "2.0", 3) == 0) { 5152 /* 5153 * Either we couldn't find out what kernel release 5154 * this is, or it's a 2.0[.x] kernel. 5155 * 5156 * In the 2.0[.x] kernel, a "recvfrom()" on 5157 * a SOCK_PACKET socket, with MSG_TRUNC set, will 5158 * return the number of bytes read, so if we pass 5159 * a length based on the snapshot length, it'll 5160 * return the number of bytes from the packet 5161 * copied to userland, not the actual length 5162 * of the packet. 5163 * 5164 * This means that, for example, the IP dissector 5165 * in tcpdump will get handed a packet length less 5166 * than the length in the IP header, and will 5167 * complain about "truncated-ip". 5168 * 5169 * So we don't bother trying to copy from the 5170 * kernel only the bytes in which we're interested, 5171 * but instead copy them all, just as the older 5172 * versions of libpcap for Linux did. 5173 * 5174 * The buffer therefore needs to be big enough to 5175 * hold the largest packet we can get from this 5176 * device. Unfortunately, we can't get the MRU 5177 * of the network; we can only get the MTU. The 5178 * MTU may be too small, in which case a packet larger 5179 * than the buffer size will be truncated *and* we 5180 * won't get the actual packet size. 5181 * 5182 * However, if the snapshot length is larger than 5183 * the buffer size based on the MTU, we use the 5184 * snapshot length as the buffer size, instead; 5185 * this means that with a sufficiently large snapshot 5186 * length we won't artificially truncate packets 5187 * to the MTU-based size. 5188 * 5189 * This mess just one of many problems with packet 5190 * capture on 2.0[.x] kernels; you really want a 5191 * 2.2[.x] or later kernel if you want packet capture 5192 * to work well. 5193 */ 5194 mtu = iface_get_mtu(handle->fd, device, handle->errbuf); 5195 if (mtu == -1) 5196 return PCAP_ERROR; 5197 handle->bufsize = MAX_LINKHEADER_SIZE + mtu; 5198 if (handle->bufsize < handle->snapshot) 5199 handle->bufsize = handle->snapshot; 5200 } else { 5201 /* 5202 * This is a 2.2[.x] or later kernel. 5203 * 5204 * We can safely pass "recvfrom()" a byte count 5205 * based on the snapshot length. 5206 */ 5207 handle->bufsize = handle->snapshot; 5208 } 5209 5210 /* 5211 * Default value for offset to align link-layer payload 5212 * on a 4-byte boundary. 5213 */ 5214 handle->offset = 0; 5215 5216 return 1; 5217 } 5218 5219 /* 5220 * Bind the socket associated with FD to the given device using the 5221 * interface of the old kernels. 5222 */ 5223 static int 5224 iface_bind_old(int fd, const char *device, char *ebuf) 5225 { 5226 struct sockaddr saddr; 5227 int err; 5228 socklen_t errlen = sizeof(err); 5229 5230 memset(&saddr, 0, sizeof(saddr)); 5231 strncpy(saddr.sa_data, device, sizeof(saddr.sa_data)); 5232 if (bind(fd, &saddr, sizeof(saddr)) == -1) { 5233 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5234 "bind: %s", pcap_strerror(errno)); 5235 return -1; 5236 } 5237 5238 /* Any pending errors, e.g., network is down? */ 5239 5240 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { 5241 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5242 "getsockopt: %s", pcap_strerror(errno)); 5243 return -1; 5244 } 5245 5246 if (err > 0) { 5247 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5248 "bind: %s", pcap_strerror(err)); 5249 return -1; 5250 } 5251 5252 return 0; 5253 } 5254 5255 5256 /* ===== System calls available on all supported kernels ============== */ 5257 5258 /* 5259 * Query the kernel for the MTU of the given interface. 5260 */ 5261 static int 5262 iface_get_mtu(int fd, const char *device, char *ebuf) 5263 { 5264 struct ifreq ifr; 5265 5266 if (!device) 5267 return BIGGER_THAN_ALL_MTUS; 5268 5269 memset(&ifr, 0, sizeof(ifr)); 5270 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5271 5272 if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { 5273 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5274 "SIOCGIFMTU: %s", pcap_strerror(errno)); 5275 return -1; 5276 } 5277 5278 return ifr.ifr_mtu; 5279 } 5280 5281 /* 5282 * Get the hardware type of the given interface as ARPHRD_xxx constant. 5283 */ 5284 static int 5285 iface_get_arptype(int fd, const char *device, char *ebuf) 5286 { 5287 struct ifreq ifr; 5288 5289 memset(&ifr, 0, sizeof(ifr)); 5290 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 5291 5292 if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { 5293 snprintf(ebuf, PCAP_ERRBUF_SIZE, 5294 "SIOCGIFHWADDR: %s", pcap_strerror(errno)); 5295 if (errno == ENODEV) { 5296 /* 5297 * No such device. 5298 */ 5299 return PCAP_ERROR_NO_SUCH_DEVICE; 5300 } 5301 return PCAP_ERROR; 5302 } 5303 5304 return ifr.ifr_hwaddr.sa_family; 5305 } 5306 5307 #ifdef SO_ATTACH_FILTER 5308 static int 5309 fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) 5310 { 5311 size_t prog_size; 5312 register int i; 5313 register struct bpf_insn *p; 5314 struct bpf_insn *f; 5315 int len; 5316 5317 /* 5318 * Make a copy of the filter, and modify that copy if 5319 * necessary. 5320 */ 5321 prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len; 5322 len = handle->fcode.bf_len; 5323 f = (struct bpf_insn *)malloc(prog_size); 5324 if (f == NULL) { 5325 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5326 "malloc: %s", pcap_strerror(errno)); 5327 return -1; 5328 } 5329 memcpy(f, handle->fcode.bf_insns, prog_size); 5330 fcode->len = len; 5331 fcode->filter = (struct sock_filter *) f; 5332 5333 for (i = 0; i < len; ++i) { 5334 p = &f[i]; 5335 /* 5336 * What type of instruction is this? 5337 */ 5338 switch (BPF_CLASS(p->code)) { 5339 5340 case BPF_RET: 5341 /* 5342 * It's a return instruction; are we capturing 5343 * in memory-mapped mode? 5344 */ 5345 if (!is_mmapped) { 5346 /* 5347 * No; is the snapshot length a constant, 5348 * rather than the contents of the 5349 * accumulator? 5350 */ 5351 if (BPF_MODE(p->code) == BPF_K) { 5352 /* 5353 * Yes - if the value to be returned, 5354 * i.e. the snapshot length, is 5355 * anything other than 0, make it 5356 * 65535, so that the packet is 5357 * truncated by "recvfrom()", 5358 * not by the filter. 5359 * 5360 * XXX - there's nothing we can 5361 * easily do if it's getting the 5362 * value from the accumulator; we'd 5363 * have to insert code to force 5364 * non-zero values to be 65535. 5365 */ 5366 if (p->k != 0) 5367 p->k = 65535; 5368 } 5369 } 5370 break; 5371 5372 case BPF_LD: 5373 case BPF_LDX: 5374 /* 5375 * It's a load instruction; is it loading 5376 * from the packet? 5377 */ 5378 switch (BPF_MODE(p->code)) { 5379 5380 case BPF_ABS: 5381 case BPF_IND: 5382 case BPF_MSH: 5383 /* 5384 * Yes; are we in cooked mode? 5385 */ 5386 if (handle->md.cooked) { 5387 /* 5388 * Yes, so we need to fix this 5389 * instruction. 5390 */ 5391 if (fix_offset(p) < 0) { 5392 /* 5393 * We failed to do so. 5394 * Return 0, so our caller 5395 * knows to punt to userland. 5396 */ 5397 return 0; 5398 } 5399 } 5400 break; 5401 } 5402 break; 5403 } 5404 } 5405 return 1; /* we succeeded */ 5406 } 5407 5408 static int 5409 fix_offset(struct bpf_insn *p) 5410 { 5411 /* 5412 * What's the offset? 5413 */ 5414 if (p->k >= SLL_HDR_LEN) { 5415 /* 5416 * It's within the link-layer payload; that starts at an 5417 * offset of 0, as far as the kernel packet filter is 5418 * concerned, so subtract the length of the link-layer 5419 * header. 5420 */ 5421 p->k -= SLL_HDR_LEN; 5422 } else if (p->k == 0) { 5423 /* 5424 * It's the packet type field; map it to the special magic 5425 * kernel offset for that field. 5426 */ 5427 p->k = SKF_AD_OFF + SKF_AD_PKTTYPE; 5428 } else if (p->k == 14) { 5429 /* 5430 * It's the protocol field; map it to the special magic 5431 * kernel offset for that field. 5432 */ 5433 p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; 5434 } else if ((bpf_int32)(p->k) > 0) { 5435 /* 5436 * It's within the header, but it's not one of those 5437 * fields; we can't do that in the kernel, so punt 5438 * to userland. 5439 */ 5440 return -1; 5441 } 5442 return 0; 5443 } 5444 5445 static int 5446 set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode) 5447 { 5448 int total_filter_on = 0; 5449 int save_mode; 5450 int ret; 5451 int save_errno; 5452 5453 /* 5454 * The socket filter code doesn't discard all packets queued 5455 * up on the socket when the filter is changed; this means 5456 * that packets that don't match the new filter may show up 5457 * after the new filter is put onto the socket, if those 5458 * packets haven't yet been read. 5459 * 5460 * This means, for example, that if you do a tcpdump capture 5461 * with a filter, the first few packets in the capture might 5462 * be packets that wouldn't have passed the filter. 5463 * 5464 * We therefore discard all packets queued up on the socket 5465 * when setting a kernel filter. (This isn't an issue for 5466 * userland filters, as the userland filtering is done after 5467 * packets are queued up.) 5468 * 5469 * To flush those packets, we put the socket in read-only mode, 5470 * and read packets from the socket until there are no more to 5471 * read. 5472 * 5473 * In order to keep that from being an infinite loop - i.e., 5474 * to keep more packets from arriving while we're draining 5475 * the queue - we put the "total filter", which is a filter 5476 * that rejects all packets, onto the socket before draining 5477 * the queue. 5478 * 5479 * This code deliberately ignores any errors, so that you may 5480 * get bogus packets if an error occurs, rather than having 5481 * the filtering done in userland even if it could have been 5482 * done in the kernel. 5483 */ 5484 if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, 5485 &total_fcode, sizeof(total_fcode)) == 0) { 5486 char drain[1]; 5487 5488 /* 5489 * Note that we've put the total filter onto the socket. 5490 */ 5491 total_filter_on = 1; 5492 5493 /* 5494 * Save the socket's current mode, and put it in 5495 * non-blocking mode; we drain it by reading packets 5496 * until we get an error (which is normally a 5497 * "nothing more to be read" error). 5498 */ 5499 save_mode = fcntl(handle->fd, F_GETFL, 0); 5500 if (save_mode != -1 && 5501 fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) { 5502 while (recv(handle->fd, &drain, sizeof drain, 5503 MSG_TRUNC) >= 0) 5504 ; 5505 save_errno = errno; 5506 fcntl(handle->fd, F_SETFL, save_mode); 5507 if (save_errno != EAGAIN) { 5508 /* Fatal error */ 5509 reset_kernel_filter(handle); 5510 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, 5511 "recv: %s", pcap_strerror(save_errno)); 5512 return -2; 5513 } 5514 } 5515 } 5516 5517 /* 5518 * Now attach the new filter. 5519 */ 5520 ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, 5521 fcode, sizeof(*fcode)); 5522 if (ret == -1 && total_filter_on) { 5523 /* 5524 * Well, we couldn't set that filter on the socket, 5525 * but we could set the total filter on the socket. 5526 * 5527 * This could, for example, mean that the filter was 5528 * too big to put into the kernel, so we'll have to 5529 * filter in userland; in any case, we'll be doing 5530 * filtering in userland, so we need to remove the 5531 * total filter so we see packets. 5532 */ 5533 save_errno = errno; 5534 5535 /* 5536 * XXX - if this fails, we're really screwed; 5537 * we have the total filter on the socket, 5538 * and it won't come off. What do we do then? 5539 */ 5540 reset_kernel_filter(handle); 5541 5542 errno = save_errno; 5543 } 5544 return ret; 5545 } 5546 5547 static int 5548 reset_kernel_filter(pcap_t *handle) 5549 { 5550 /* 5551 * setsockopt() barfs unless it get a dummy parameter. 5552 * valgrind whines unless the value is initialized, 5553 * as it has no idea that setsockopt() ignores its 5554 * parameter. 5555 */ 5556 int dummy = 0; 5557 5558 return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, 5559 &dummy, sizeof(dummy)); 5560 } 5561 #endif 5562