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