X-Git-Url: https://git.tcpdump.org/libpcap/blobdiff_plain/18d5f5efc112e1a8ae3df7592e49feda2b3eab93..6de2dedb10df2f18db55e41f59b47824de314279:/pcap-linux.c diff --git a/pcap-linux.c b/pcap-linux.c index 1a238891..de14a7ec 100644 --- a/pcap-linux.c +++ b/pcap-linux.c @@ -30,6 +30,39 @@ * based on previous works of: * Simon Patarin * Phil Wood + * + * Monitor-mode support for mac80211 includes code taken from the iw + * command; the copyright notice for that code is + * + * Copyright (c) 2007, 2008 Johannes Berg + * Copyright (c) 2007 Andy Lutomirski + * Copyright (c) 2007 Mike Kershaw + * Copyright (c) 2008 Gábor Stefanik + * + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. */ #ifndef lint @@ -80,15 +113,19 @@ static const char rcsid[] _U_ = */ +#define _GNU_SOURCE + #ifdef HAVE_CONFIG_H #include "config.h" #endif #include +#include #include #include #include #include +#include #include #include #include @@ -104,7 +141,20 @@ static const char rcsid[] _U_ = */ #ifdef HAVE_LINUX_WIRELESS_H #include -#endif +#endif /* HAVE_LINUX_WIRELESS_H */ + +/* + * Got libnl? + */ +#ifdef HAVE_LIBNL +#include + +#include +#include +#include +#include +#include +#endif /* HAVE_LIBNL */ #include "pcap-int.h" #include "pcap/sll.h" @@ -245,6 +295,12 @@ static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); static void pcap_cleanup_linux(pcap_t *); +union thdr { + struct tpacket_hdr *h1; + struct tpacket2_hdr *h2; + void *raw; +}; + #ifdef HAVE_PACKET_RING #define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset]) @@ -256,6 +312,8 @@ static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *); static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf); static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf); +static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes); #endif /* @@ -271,13 +329,14 @@ static int iface_bind(int fd, int ifindex, char *ebuf); #ifdef IW_MODE_MONITOR static int has_wext(int sock_fd, const char *device, char *ebuf); #endif /* IW_MODE_MONITOR */ -static int enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, +static int enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device); #endif /* HAVE_PF_PACKET_SOCKETS */ static int iface_bind_old(int fd, const char *device, char *ebuf); #ifdef SO_ATTACH_FILTER -static int fix_program(pcap_t *handle, struct sock_fprog *fcode); +static int fix_program(pcap_t *handle, struct sock_fprog *fcode, + int is_mapped); static int fix_offset(struct bpf_insn *p); static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); static int reset_kernel_filter(pcap_t *handle); @@ -332,21 +391,462 @@ pcap_create(const char *device, char *ebuf) return handle; } +#ifdef HAVE_LIBNL +/* + * + * If interface {if} is a mac80211 driver, the file + * /sys/class/net/{if}/phy80211 is a symlink to + * /sys/class/ieee80211/{phydev}, for some {phydev}. + * + * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at + * least, has a "wmaster0" device and a "wlan0" device; the + * latter is the one with the IP address. Both show up in + * "tcpdump -D" output. Capturing on the wmaster0 device + * captures with 802.11 headers. + * + * airmon-ng searches through /sys/class/net for devices named + * monN, starting with mon0; as soon as one *doesn't* exist, + * it chooses that as the monitor device name. If the "iw" + * command exists, it does "iw dev {if} interface add {monif} + * type monitor", where {monif} is the monitor device. It + * then (sigh) sleeps .1 second, and then configures the + * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface + * is a file, it writes {mondev}, without a newline, to that file, + * and again (sigh) sleeps .1 second, and then iwconfig's that + * device into monitor mode and configures it up. Otherwise, + * you can't do monitor mode. + * + * All these devices are "glued" together by having the + * /sys/class/net/{device}/phy80211 links pointing to the same + * place, so, given a wmaster, wlan, or mon device, you can + * find the other devices by looking for devices with + * the same phy80211 link. + * + * To turn monitor mode off, delete the monitor interface, + * either with "iw dev {monif} interface del" or by sending + * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface + * + * Note: if you try to create a monitor device named "monN", and + * there's already a "monN" device, it fails, as least with + * the netlink interface (which is what iw uses), with a return + * value of -ENFILE. (Return values are negative errnos.) We + * could probably use that to find an unused device. + * + * Yes, you can have multiple monitor devices for a given + * physical device. +*/ + +/* + * Is this a mac80211 device? If so, fill in the physical device path and + * return 1; if not, return 0. On an error, fill in handle->errbuf and + * return PCAP_ERROR. + */ +static int +get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, + size_t phydev_max_pathlen) +{ + char *pathstr; + ssize_t bytes_read; + + /* + * Generate the path string for the symlink to the physical device. + */ + if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't generate path name string for /sys/class/net device", + device); + return PCAP_ERROR; + } + bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); + if (bytes_read == -1) { + if (errno == ENOENT || errno == EINVAL) { + /* + * Doesn't exist, or not a symlink; assume that + * means it's not a mac80211 device. + */ + free(pathstr); + return 0; + } + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't readlink %s: %s", device, pathstr, + strerror(errno)); + free(pathstr); + return PCAP_ERROR; + } + free(pathstr); + phydev_path[bytes_read] = '\0'; + return 1; +} + +struct nl80211_state { + struct nl_handle *nl_handle; + struct nl_cache *nl_cache; + struct genl_family *nl80211; +}; + +static int +nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) +{ + state->nl_handle = nl_handle_alloc(); + if (!state->nl_handle) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink handle", device); + return PCAP_ERROR; + } + + if (genl_connect(state->nl_handle)) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to connect to generic netlink", device); + goto out_handle_destroy; + } + + state->nl_cache = genl_ctrl_alloc_cache(state->nl_handle); + if (!state->nl_cache) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate generic netlink cache", device); + goto out_handle_destroy; + } + + state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); + if (!state->nl80211) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl80211 not found", device); + goto out_cache_free; + } + + return 0; + +out_cache_free: + nl_cache_free(state->nl_cache); +out_handle_destroy: + nl_handle_destroy(state->nl_handle); + return PCAP_ERROR; +} + +static void +nl80211_cleanup(struct nl80211_state *state) +{ + genl_family_put(state->nl80211); + nl_cache_free(state->nl_cache); + nl_handle_destroy(state->nl_handle); +} + +static int +add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, device, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_NEW_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); + NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); + + err = nl_send_auto_complete(state->nl_handle, msg); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + err = nl_wait_for_ack(state->nl_handle); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + + /* + * Success. + */ + nlmsg_free(msg); + return 1; + +nla_put_failure: + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed adding %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, + const char *device, const char *mondevice) +{ + int ifindex; + struct nl_msg *msg; + int err; + + ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); + if (ifindex == -1) + return PCAP_ERROR; + + msg = nlmsg_alloc(); + if (!msg) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: failed to allocate netlink msg", device); + return PCAP_ERROR; + } + + genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, + 0, NL80211_CMD_DEL_INTERFACE, 0); + NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); + + err = nl_send_auto_complete(state->nl_handle, msg); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_send_auto_complete failed deleting %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + err = nl_wait_for_ack(state->nl_handle); + if (err < 0) { + if (err == -ENFILE) { + /* + * Device not available; our caller should just + * keep trying. + */ + nlmsg_free(msg); + return 0; + } else { + /* + * Real failure, not just "that device is not + * available. + */ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_wait_for_ack failed adding %s interface: %s", + device, mondevice, strerror(-err)); + nlmsg_free(msg); + return PCAP_ERROR; + } + } + + /* + * Success. + */ + nlmsg_free(msg); + return 1; + +nla_put_failure: + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: nl_put failed deleting %s interface", + device, mondevice); + nlmsg_free(msg); + return PCAP_ERROR; +} + +static int +enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) +{ + int ret; + char phydev_path[PATH_MAX+1]; + struct nl80211_state nlstate; + struct ifreq ifr; + u_int n; + + /* + * Is this a mac80211 device? + */ + ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 0) + return 0; /* no error, but not mac80211 device */ + + /* + * XXX - is this already a monN device? + * If so, we're done. + * Is that determined by old Wireless Extensions ioctls? + */ + + /* + * OK, it's apparently a mac80211 device. + * Try to find an unused monN device for it. + */ + ret = nl80211_init(handle, &nlstate, device); + if (ret != 0) + return ret; + for (n = 0; n < UINT_MAX; n++) { + /* + * Try mon{n}. + */ + char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ + + snprintf(mondevice, sizeof mondevice, "mon%u", n); + ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); + if (ret == 1) { + handle->md.mondevice = strdup(mondevice); + goto added; + } + if (ret < 0) { + /* + * Hard failure. Just return ret; handle->errbuf + * has already been set. + */ + nl80211_cleanup(&nlstate); + return ret; + } + } + + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: No free monN interfaces", device); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + +added: + +#if 0 + /* + * Sleep for .1 seconds. + */ + delay.tv_sec = 0; + delay.tv_nsec = 500000000; + nanosleep(&delay, NULL); +#endif + + /* + * Now configure the monitor interface up. + */ + memset(&ifr, 0, sizeof(ifr)); + strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name)); + if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't get flags for %s: %s", device, + handle->md.mondevice, strerror(errno)); + del_mon_if(handle, sock_fd, &nlstate, device, + handle->md.mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + ifr.ifr_flags |= IFF_UP|IFF_RUNNING; + if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "%s: Can't set flags for %s: %s", device, + handle->md.mondevice, strerror(errno)); + del_mon_if(handle, sock_fd, &nlstate, device, + handle->md.mondevice); + nl80211_cleanup(&nlstate); + return PCAP_ERROR; + } + + /* + * Success. Clean up the libnl state. + */ + nl80211_cleanup(&nlstate); + + /* + * Note that we have to delete the monitor device when we close + * the handle. + */ + handle->md.must_do_on_close |= MUST_DELETE_MONIF; + + /* + * Add this to the list of pcaps to close when we exit. + */ + pcap_add_to_pcaps_to_close(handle); + + return 1; +} +#endif /* HAVE_LIBNL */ + static int -pcap_can_set_rfmon_linux(pcap_t *p) +pcap_can_set_rfmon_linux(pcap_t *handle) { +#ifdef HAVE_LIBNL + char phydev_path[PATH_MAX+1]; + int ret; +#endif #ifdef IW_MODE_MONITOR int sock_fd; struct iwreq ireq; #endif - if (strcmp(p->opt.source, "any") == 0) { + if (strcmp(handle->opt.source, "any") == 0) { /* * Monitor mode makes no sense on the "any" device. */ return 0; } +#ifdef HAVE_LIBNL + /* + * Bleah. There doesn't seem to be a way to ask a mac80211 + * device, through libnl, whether it supports monitor mode; + * we'll just check whether the device appears to be a + * mac80211 device and, if so, assume the device supports + * monitor mode. + * + * wmaster devices don't appear to support the Wireless + * Extensions, but we can create a mon device for a + * wmaster device, so we don't bother checking whether + * a mac80211 device supports the Wireless Extensions. + */ + ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path, + PATH_MAX); + if (ret < 0) + return ret; /* error */ + if (ret == 1) + return 1; /* mac80211 device */ +#endif + #ifdef IW_MODE_MONITOR /* * Bleah. There doesn't appear to be an ioctl to use to ask @@ -360,7 +860,7 @@ pcap_can_set_rfmon_linux(pcap_t *p) */ sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (sock_fd == -1) { - (void)snprintf(p->errbuf, PCAP_ERRBUF_SIZE, + (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); return PCAP_ERROR; } @@ -368,7 +868,7 @@ pcap_can_set_rfmon_linux(pcap_t *p) /* * Attempt to get the current mode. */ - strncpy(ireq.ifr_ifrn.ifrn_name, p->opt.source, + strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source, sizeof ireq.ifr_ifrn.ifrn_name); ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { @@ -403,16 +903,20 @@ pcap_can_set_rfmon_linux(pcap_t *p) static void pcap_cleanup_linux( pcap_t *handle ) { struct ifreq ifr; +#ifdef HAVE_LIBNL + struct nl80211_state nlstate; + int ret; +#endif /* HAVE_LIBNL */ #ifdef IW_MODE_MONITOR struct iwreq ireq; -#endif +#endif /* IW_MODE_MONITOR */ - if (handle->md.must_clear != 0) { + if (handle->md.must_do_on_close != 0) { /* * There's something we have to do when closing this * pcap_t. */ - if (handle->md.must_clear & MUST_CLEAR_PROMISC) { + if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) { /* * We put the interface into promiscuous mode; * take it out of promiscuous mode. @@ -450,8 +954,25 @@ static void pcap_cleanup_linux( pcap_t *handle ) } } +#ifdef HAVE_LIBNL + if (handle->md.must_do_on_close & MUST_DELETE_MONIF) { + ret = nl80211_init(handle, &nlstate, handle->md.device); + if (ret >= 0) { + ret = del_mon_if(handle, handle->fd, &nlstate, + handle->md.device, handle->md.mondevice); + nl80211_cleanup(&nlstate); + } + if (ret < 0) { + fprintf(stderr, + "Can't delete monitor interface %s (%s).\n" + "Please delete manually.\n", + handle->md.mondevice, handle->errbuf); + } + } +#endif /* HAVE_LIBNL */ + #ifdef IW_MODE_MONITOR - if (handle->md.must_clear & MUST_CLEAR_RFMON) { + if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) { /* * We put the interface into rfmon mode; * take it out of rfmon mode. @@ -475,7 +996,7 @@ static void pcap_cleanup_linux( pcap_t *handle ) strerror(errno)); } } -#endif +#endif /* IW_MODE_MONITOR */ /* * Take this pcap out of the list of pcaps for which we @@ -484,6 +1005,10 @@ static void pcap_cleanup_linux( pcap_t *handle ) pcap_remove_from_pcaps_to_close(handle); } + if (handle->md.mondevice != NULL) { + free(handle->md.mondevice); + handle->md.mondevice = NULL; + } if (handle->md.device != NULL) { free(handle->md.device); handle->md.device = NULL; @@ -1170,7 +1695,8 @@ pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) * Attach the given BPF code to the packet capture device. */ static int -pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) +pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, + int is_mmapped) { #ifdef SO_ATTACH_FILTER struct sock_fprog fcode; @@ -1223,13 +1749,13 @@ pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) * * Oh, and we also need to fix it up so that all "ret" * instructions with non-zero operands have 65535 as the - * operand, and so that, if we're in cooked mode, all - * memory-reference instructions use special magic offsets - * in references to the link-layer header and assume that - * the link-layer payload begins at 0; "fix_program()" - * will do that. + * operand if we're not capturing in memory-mapped modee, + * and so that, if we're in cooked mode, all memory-reference + * instructions use special magic offsets in references to + * the link-layer header and assume that the link-layer + * payload begins at 0; "fix_program()" will do that. */ - switch (fix_program(handle, &fcode)) { + switch (fix_program(handle, &fcode, is_mmapped)) { case -1: default: @@ -1303,6 +1829,13 @@ pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) return 0; } +static int +pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) +{ + return pcap_setfilter_linux_common(handle, filter, 0); +} + + /* * Set direction flag: Which packets do we accept on a forwarding * single device? IN, OUT or both? @@ -1687,7 +2220,10 @@ activate_new(pcap_t *handle) #ifdef HAVE_PF_PACKET_SOCKETS const char *device = handle->opt.source; int is_any_device = (strcmp(device, "any") == 0); - int sock_fd = -1, arptype, val; + int sock_fd = -1, arptype; +#ifdef HAVE_PACKET_AUXDATA + int val; +#endif int err = 0; struct packet_mreq mr; @@ -1745,7 +2281,7 @@ activate_new(pcap_t *handle) * because entering monitor mode could change * the link-layer type. */ - err = enter_rfmon_mode_wext(handle, sock_fd, device); + err = enter_rfmon_mode(handle, sock_fd, device); if (err < 0) { /* Hard failure */ close(sock_fd); @@ -1759,6 +2295,15 @@ activate_new(pcap_t *handle) close(sock_fd); return PCAP_ERROR_RFMON_NOTSUP; } + + /* + * Either monitor mode has been turned on for + * the device, or we've been given a different + * device to open for monitor mode. If we've + * been given a different device, use it. + */ + if (handle->md.mondevice != NULL) + device = handle->md.mondevice; } arptype = iface_get_arptype(sock_fd, device, handle->errbuf); if (arptype < 0) { @@ -1961,16 +2506,32 @@ activate_mmap(pcap_t *handle) #ifdef HAVE_PACKET_RING int ret; + /* + * Attempt to allocate a buffer to hold the contents of one + * packet, for use by the oneshot callback. + */ + handle->md.oneshot_buffer = malloc(handle->snapshot); + if (handle->md.oneshot_buffer == NULL) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "can't allocate oneshot buffer: %s", + pcap_strerror(errno)); + return PCAP_ERROR; + } + if (handle->opt.buffer_size == 0) { /* by default request 2M for the ring buffer */ handle->opt.buffer_size = 2*1024*1024; } ret = prepare_tpacket_socket(handle); - if (ret != 1) + if (ret != 1) { + free(handle->md.oneshot_buffer); return ret; + } ret = create_ring(handle); - if (ret != 1) + if (ret != 1) { + free(handle->md.oneshot_buffer); return ret; + } /* override some defaults and inherit the other fields from * activate_new @@ -1981,6 +2542,7 @@ activate_mmap(pcap_t *handle) handle->setfilter_op = pcap_setfilter_linux_mmap; handle->setnonblock_op = pcap_setnonblock_mmap; handle->getnonblock_op = pcap_getnonblock_mmap; + handle->oneshot_callback = pcap_oneshot_mmap; handle->selectable_fd = handle->fd; return 1; #else /* HAVE_PACKET_RING */ @@ -2040,24 +2602,10 @@ prepare_tpacket_socket(pcap_t *handle) return 1; } -static void -compute_ring_block(int frame_size, unsigned *block_size, unsigned *frames_per_block) -{ - /* compute the minumum block size that will handle this frame. - * The block has to be page size aligned. - * The max block size allowed by the kernel is arch-dependent and - * it's not explicitly checked here. */ - *block_size = getpagesize(); - while (*block_size < frame_size) - *block_size <<= 1; - - *frames_per_block = *block_size/frame_size; -} - static int create_ring(pcap_t *handle) { - unsigned i, j, ringsize, frames_per_block; + unsigned i, j, frames_per_block; struct tpacket_req req; /* Note that with large snapshot (say 64K) only a few frames @@ -2069,20 +2617,40 @@ create_ring(pcap_t *handle) TPACKET_ALIGN(handle->md.tp_hdrlen) + sizeof(struct sockaddr_ll)); req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; - compute_ring_block(req.tp_frame_size, &req.tp_block_size, &frames_per_block); - req.tp_block_nr = req.tp_frame_nr / frames_per_block; - /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ - req.tp_frame_nr = req.tp_block_nr * frames_per_block; + /* compute the minumum block size that will handle this frame. + * The block has to be page size aligned. + * The max block size allowed by the kernel is arch-dependent and + * it's not explicitly checked here. */ + req.tp_block_size = getpagesize(); + while (req.tp_block_size < req.tp_frame_size) + req.tp_block_size <<= 1; + + frames_per_block = req.tp_block_size/req.tp_frame_size; /* ask the kernel to create the ring */ retry: + req.tp_block_nr = req.tp_frame_nr / frames_per_block; + + /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ + req.tp_frame_nr = req.tp_block_nr * frames_per_block; + if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, (void *) &req, sizeof(req))) { - /* try to reduce requested ring size to prevent memory failure */ if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { - req.tp_frame_nr >>= 1; - req.tp_block_nr = req.tp_frame_nr/frames_per_block; + /* + * Memory failure; try to reduce the requested ring + * size. + * + * We used to reduce this by half -- do 5% instead. + * That may result in more iterations and a longer + * startup, but the user will be much happier with + * the resulting buffer size. + */ + if (req.tp_frame_nr < 20) + req.tp_frame_nr -= 1; + else + req.tp_frame_nr -= req.tp_frame_nr/20; goto retry; } if (errno == ENOPROTOOPT) { @@ -2098,10 +2666,10 @@ retry: } /* memory map the rx ring */ - ringsize = req.tp_block_nr * req.tp_block_size; - handle->bp = mmap(0, ringsize, PROT_READ| PROT_WRITE, MAP_SHARED, - handle->fd, 0); - if (handle->bp == MAP_FAILED) { + handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size; + handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen, + PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); + if (handle->md.mmapbuf == MAP_FAILED) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't mmap rx ring: %s", pcap_strerror(errno)); @@ -2125,7 +2693,7 @@ retry: /* fill the header ring with proper frame ptr*/ handle->offset = 0; for (i=0; ibp[i*req.tp_block_size]; + void *base = &handle->md.mmapbuf[i*req.tp_block_size]; for (j=0; joffset) { RING_GET_FRAME(handle) = base; base += req.tp_frame_size; @@ -2148,21 +2716,50 @@ destroy_ring(pcap_t *handle) (void *) &req, sizeof(req)); /* if ring is mapped, unmap it*/ - if (handle->bp) { - /* need to re-compute the ring size */ - unsigned frames_per_block, block_size; - compute_ring_block(handle->bufsize, &block_size, &frames_per_block); - - /* do not perform sanity check here: we can't recover any error */ - munmap(handle->bp, block_size * handle->cc / frames_per_block); - handle->bp = 0; + if (handle->md.mmapbuf) { + /* do not test for mmap failure, as we can't recover from any error */ + munmap(handle->md.mmapbuf, handle->md.mmapbuflen); + handle->md.mmapbuf = NULL; } } +/* + * Special one-shot callback, used for pcap_next() and pcap_next_ex(), + * for Linux mmapped capture. + * + * The problem is that pcap_next() and pcap_next_ex() expect the packet + * data handed to the callback to be valid after the callback returns, + * but pcap_read_linux_mmap() has to release that packet as soon as + * the callback returns (otherwise, the kernel thinks there's still + * at least one unprocessed packet available in the ring, so a select() + * will immediately return indicating that there's data to process), so, + * in the callback, we have to make a copy of the packet. + * + * Yes, this means that, if the capture is using the ring buffer, using + * pcap_next() or pcap_next_ex() requires more copies than using + * pcap_loop() or pcap_dispatch(). If that bothers you, don't use + * pcap_next() or pcap_next_ex(). + */ +static void +pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, + const u_char *bytes) +{ + struct pkt_for_oneshot *sp = (struct pkt_for_oneshot *)user; + bpf_u_int32 copylen; + + *sp->hdr = *h; + memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen); + *sp->pkt = sp->pd->md.oneshot_buffer; +} + static void pcap_cleanup_linux_mmap( pcap_t *handle ) { destroy_ring(handle); + if (handle->md.oneshot_buffer != NULL) { + free(handle->md.oneshot_buffer); + handle->md.oneshot_buffer = NULL; + } pcap_cleanup_linux(handle); } @@ -2180,11 +2777,26 @@ pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf) /* map each value to the corresponding 2's complement, to * preserve the timeout value provided with pcap_set_timeout */ if (nonblock) { - if (p->md.timeout > 0) + if (p->md.timeout >= 0) { + /* + * Timeout is non-negative, so we're not already + * in non-blocking mode; set it to the 2's + * complement, to make it negative, as an + * indication that we're in non-blocking mode. + */ p->md.timeout = p->md.timeout*-1 - 1; - } else - if (p->md.timeout < 0) + } + } else { + if (p->md.timeout < 0) { + /* + * Timeout is negative, so we're not already + * in blocking mode; reverse the previous + * operation, to make the timeout non-negative + * again. + */ p->md.timeout = (p->md.timeout+1)*-1; + } + } return 0; } @@ -2211,24 +2823,6 @@ pcap_get_ring_frame(pcap_t *handle, int status) return h.raw; } -static inline void -pcap_release_previous_ring_frame(pcap_t *handle) -{ - if (handle->md.prev_pkt.raw != NULL) { - switch (handle->md.tp_version) { - case TPACKET_V1: - handle->md.prev_pkt.h1->tp_status = TP_STATUS_KERNEL; - break; -#ifdef HAVE_TPACKET2 - case TPACKET_V2: - handle->md.prev_pkt.h2->tp_status = TP_STATUS_KERNEL; - break; -#endif - } - handle->md.prev_pkt.raw = NULL; - } -} - static int pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) @@ -2276,44 +2870,10 @@ pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, unsigned int tp_sec; unsigned int tp_usec; - /* - * Check for break loop condition; a callback might have - * set it. - */ - if (handle->break_loop) { - handle->break_loop = 0; - return -2; - } - h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); if (!h.raw) break; - /* - * We have a packet; release the previous packet, - * if any. - * - * Libpcap has never guaranteed that, if we get a - * packet from the underlying packet capture - * mechanism, the data passed to callbacks for - * any previous packets is still valid. It did - * implicitly guarantee that the data will still - * be available after the callback returns, by - * virtue of implementing pcap_next() by calling - * pcap_dispatch() with a count of 1 and a callback - * that fills in a structure with a pointer to - * the packet data, meaning that pointer is - * expected to point to valid data after the - * callback returns and pcap_next() returns, - * so we can't release the packet when the - * callback returns. - * - * Therefore, we remember the packet that - * needs to be released after handing it - * to the callback, and release it up here. - */ - pcap_release_previous_ring_frame(handle); - switch (handle->md.tp_version) { case TPACKET_V1: tp_len = h.h1->tp_len; @@ -2458,20 +3018,35 @@ pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback, } #endif + /* + * The only way to tell the kernel to cut off the + * packet at a snapshot length is with a filter program; + * if there's no filter program, the kernel won't cut + * the packet off. + * + * Trim the snapshot length to be no longer than the + * specified snapshot length. + */ + if (pcaphdr.caplen > handle->snapshot) + pcaphdr.caplen = handle->snapshot; + /* pass the packet to the user */ pkts++; callback(user, &pcaphdr, bp); handle->md.packets_read++; skip: - /* - * As per the comment above, we can't yet release this - * packet, even though the callback has returned, as - * some users of pcap_loop() and pcap_dispatch() - such - * as pcap_next() and pcap_next_ex() - expect the packet - * to be available until the next pcap_dispatch() call. - */ - handle->md.prev_pkt = h; + /* next packet */ + switch (handle->md.tp_version) { + case TPACKET_V1: + h.h1->tp_status = TP_STATUS_KERNEL; + break; +#ifdef HAVE_TPACKET2 + case TPACKET_V2: + h.h2->tp_status = TP_STATUS_KERNEL; + break; +#endif + } if (++handle->offset >= handle->cc) handle->offset = 0; @@ -2488,7 +3063,15 @@ static int pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) { int n, offset; - int ret = pcap_setfilter_linux(handle, filter); + int ret; + + /* + * Don't rewrite "ret" instructions; we don't need to, as + * we're not reading packets with recvmsg(), and we don't + * want to, as, by not rewriting them, the kernel can avoid + * copying extra data. + */ + ret = pcap_setfilter_linux_common(handle, filter, 1); if (ret < 0) return ret; @@ -2624,7 +3207,6 @@ has_wext(int sock_fd, const char *device, char *ebuf) return PCAP_ERROR_NO_SUCH_DEVICE; return 0; } -#endif /* * Per me si va ne la citta dolente, @@ -2658,7 +3240,6 @@ typedef enum { static int enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) { -#ifdef IW_MODE_MONITOR /* * XXX - at least some adapters require non-Wireless Extensions * mechanisms to turn monitor mode on. @@ -2746,7 +3327,7 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) strncpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; - ireq.u.data.pointer = args; + ireq.u.data.pointer = (void *)args; ireq.u.data.length = 0; ireq.u.data.flags = 0; if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { @@ -2776,7 +3357,7 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) "malloc: %s", pcap_strerror(errno)); return PCAP_ERROR; } - ireq.u.data.pointer = priv; + ireq.u.data.pointer = (void *)priv; if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); @@ -2796,8 +3377,10 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) * Hostap driver, use this one. * Set monitor mode first. * You can set it to 0 to get DLT_IEEE80211, - * 1 to get DLT_PRISM, or 2 to get - * DLT_IEEE80211_RADIO_AVS. + * 1 to get DLT_PRISM, 2 to get + * DLT_IEEE80211_RADIO_AVS, and, with more + * recent versions of the driver, 3 to get + * DLT_IEEE80211_RADIO. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; @@ -3011,7 +3594,7 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) * Note that we have to put the old mode back * when we close the device. */ - handle->md.must_clear |= MUST_CLEAR_RFMON; + handle->md.must_do_on_close |= MUST_CLEAR_RFMON; /* * Add this to the list of pcaps to close @@ -3060,8 +3643,19 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) case MONITOR_HOSTAP: /* - * Select the AVS header if we can, otherwise - * select the Prism header. + * Try to select the radiotap header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 3; /* request radiotap header */ + memcpy(ireq.u.name, args, sizeof (int)); + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the AVS header. */ memset(&ireq, 0, sizeof ireq); strncpy(ireq.ifr_ifrn.ifrn_name, device, @@ -3069,18 +3663,19 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; args[0] = 2; /* request AVS header */ memcpy(ireq.u.name, args, sizeof (int)); - if (ioctl(sock_fd, cmd, &ireq) == -1) { - /* - * Failure - try the Prism header. - */ - memset(&ireq, 0, sizeof ireq); - strncpy(ireq.ifr_ifrn.ifrn_name, device, - sizeof ireq.ifr_ifrn.ifrn_name); - ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; - args[0] = 1; /* request Prism header */ - memcpy(ireq.u.name, args, sizeof (int)); - ioctl(sock_fd, cmd, &ireq); - } + if (ioctl(sock_fd, cmd, &ireq) != -1) + break; /* success */ + + /* + * That failed. Try to select the Prism header. + */ + memset(&ireq, 0, sizeof ireq); + strncpy(ireq.ifr_ifrn.ifrn_name, device, + sizeof ireq.ifr_ifrn.ifrn_name); + ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0; + args[0] = 1; /* request Prism header */ + memcpy(ireq.u.name, args, sizeof (int)); + ioctl(sock_fd, cmd, &ireq); break; case MONITOR_PRISM: @@ -3191,7 +3786,7 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) * Note that we have to put the old mode back when we * close the device. */ - handle->md.must_clear |= MUST_CLEAR_RFMON; + handle->md.must_do_on_close |= MUST_CLEAR_RFMON; /* * Add this to the list of pcaps to close when we exit. @@ -3199,13 +3794,41 @@ enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) pcap_add_to_pcaps_to_close(handle); return 1; -#else +} +#endif /* IW_MODE_MONITOR */ + +/* + * Try various mechanisms to enter monitor mode. + */ +static int +enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) +{ +#if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) + int ret; +#endif + +#ifdef HAVE_LIBNL + ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* HAVE_LIBNL */ + +#ifdef IW_MODE_MONITOR + ret = enter_rfmon_mode_wext(handle, sock_fd, device); + if (ret < 0) + return ret; /* error attempting to do so */ + if (ret == 1) + return 1; /* success */ +#endif /* IW_MODE_MONITOR */ + /* - * We don't have the Wireless Extensions available, so we can't - * do monitor mode. + * Either none of the mechanisms we know about work or none + * of those mechanisms are available, so we can't do monitor + * mode. */ return 0; -#endif } #endif /* HAVE_PF_PACKET_SOCKETS */ @@ -3307,7 +3930,7 @@ activate_old(pcap_t *handle) pcap_strerror(errno)); return PCAP_ERROR; } - handle->md.must_clear |= MUST_CLEAR_PROMISC; + handle->md.must_do_on_close |= MUST_CLEAR_PROMISC; /* * Add this to the list of pcaps @@ -3482,7 +4105,7 @@ iface_get_arptype(int fd, const char *device, char *ebuf) #ifdef SO_ATTACH_FILTER static int -fix_program(pcap_t *handle, struct sock_fprog *fcode) +fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) { size_t prog_size; register int i; @@ -3515,26 +4138,33 @@ fix_program(pcap_t *handle, struct sock_fprog *fcode) case BPF_RET: /* - * It's a return instruction; is the snapshot - * length a constant, rather than the contents - * of the accumulator? + * It's a return instruction; are we capturing + * in memory-mapped mode? */ - if (BPF_MODE(p->code) == BPF_K) { + if (!is_mmapped) { /* - * Yes - if the value to be returned, - * i.e. the snapshot length, is anything - * other than 0, make it 65535, so that - * the packet is truncated by "recvfrom()", - * not by the filter. - * - * XXX - there's nothing we can easily do - * if it's getting the value from the - * accumulator; we'd have to insert - * code to force non-zero values to be - * 65535. + * No; is the snapshot length a constant, + * rather than the contents of the + * accumulator? */ - if (p->k != 0) - p->k = 65535; + if (BPF_MODE(p->code) == BPF_K) { + /* + * Yes - if the value to be returned, + * i.e. the snapshot length, is + * anything other than 0, make it + * 65535, so that the packet is + * truncated by "recvfrom()", + * not by the filter. + * + * XXX - there's nothing we can + * easily do if it's getting the + * value from the accumulator; we'd + * have to insert code to force + * non-zero values to be 65535. + */ + if (p->k != 0) + p->k = 65535; + } } break;