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