From: Jakub Zawadzki Date: Fri, 17 Jun 2011 03:06:51 +0000 (-0700) Subject: Add support for capturing from Linux iptables NFLOG log groups. X-Git-Tag: libpcap-1.2.1~44 X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/cc8520ff5294900d93509eaf843684c51af102a9 Add support for capturing from Linux iptables NFLOG log groups. Reviewed-By: Guy Harris --- diff --git a/Makefile.in b/Makefile.in index e6cd3696..b59a96e1 100644 --- a/Makefile.in +++ b/Makefile.in @@ -82,7 +82,7 @@ YACC = @V_YACC@ @rm -f $@ $(CC) $(FULL_CFLAGS) -c $(srcdir)/$*.c -PSRC = pcap-@V_PCAP@.c @USB_SRC@ @BT_SRC@ @CAN_SRC@ +PSRC = pcap-@V_PCAP@.c @USB_SRC@ @BT_SRC@ @CAN_SRC@ @NETFILTER_SRC@ FSRC = fad-@V_FINDALLDEVS@.c SSRC = @SSRC@ CSRC = pcap.c inet.c gencode.c optimize.c nametoaddr.c etherent.c \ @@ -299,6 +299,7 @@ EXTRA_DIST = \ pcap-libdlpi.c \ pcap-linux.c \ pcap-namedb.h \ + pcap-netfilter-linux.c \ pcap-nit.c \ pcap-null.c \ pcap-pf.c \ diff --git a/config.h.in b/config.h.in index c9627b2b..fb5ae096 100644 --- a/config.h.in +++ b/config.h.in @@ -244,6 +244,9 @@ /* target host supports CAN sniffing */ #undef PCAP_SUPPORT_CAN +/* target host supports netfilter sniffing */ +#undef PCAP_SUPPORT_NETFILTER + /* target host supports USB sniffing */ #undef PCAP_SUPPORT_USB diff --git a/configure b/configure index 4a649a5a..8af3b65c 100755 --- a/configure +++ b/configure @@ -697,6 +697,8 @@ MAN_FILE_FORMATS MAN_MISC_INFO PCAP_SUPPORT_USB USB_SRC +PCAP_SUPPORT_NETFILTER +NETFILTER_SRC PCAP_SUPPORT_BT BT_SRC PCAP_SUPPORT_CAN @@ -11187,6 +11189,27 @@ esac +{ echo "$as_me:$LINENO: checking for netfilter sniffing support" >&5 +echo $ECHO_N "checking for netfilter sniffing support... $ECHO_C" >&6; } +case "$host_os" in +linux*) + +cat >>confdefs.h <<\_ACEOF +#define PCAP_SUPPORT_NETFILTER 1 +_ACEOF + + NETFILTER_SRC=pcap-netfilter-linux.c + { echo "$as_me:$LINENO: result: yes" >&5 +echo "${ECHO_T}yes" >&6; } + ;; +*) + { echo "$as_me:$LINENO: result: no" >&5 +echo "${ECHO_T}no" >&6; } + ;; +esac + + + # Check whether --enable-bluetooth was given. if test "${enable_bluetooth+set}" = set; then enableval=$enable_bluetooth; @@ -12379,6 +12402,8 @@ MAN_FILE_FORMATS!$MAN_FILE_FORMATS$ac_delim MAN_MISC_INFO!$MAN_MISC_INFO$ac_delim PCAP_SUPPORT_USB!$PCAP_SUPPORT_USB$ac_delim USB_SRC!$USB_SRC$ac_delim +PCAP_SUPPORT_NETFILTER!$PCAP_SUPPORT_NETFILTER$ac_delim +NETFILTER_SRC!$NETFILTER_SRC$ac_delim PCAP_SUPPORT_BT!$PCAP_SUPPORT_BT$ac_delim BT_SRC!$BT_SRC$ac_delim PCAP_SUPPORT_CAN!$PCAP_SUPPORT_CAN$ac_delim @@ -12389,7 +12414,7 @@ INSTALL_DATA!$INSTALL_DATA$ac_delim LTLIBOBJS!$LTLIBOBJS$ac_delim _ACEOF - if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 91; then + if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 93; then break elif $ac_last_try; then { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5 diff --git a/configure.in b/configure.in index 7a9e446a..f5f374ee 100644 --- a/configure.in +++ b/configure.in @@ -1311,6 +1311,21 @@ esac AC_SUBST(PCAP_SUPPORT_USB) AC_SUBST(USB_SRC) +dnl check for netfilter sniffing support +AC_MSG_CHECKING(for netfilter sniffing support) +case "$host_os" in +linux*) + AC_DEFINE(PCAP_SUPPORT_NETFILTER, 1, [target host supports netfilter sniffing]) + NETFILTER_SRC=pcap-netfilter-linux.c + AC_MSG_RESULT(yes) + ;; +*) + AC_MSG_RESULT(no) + ;; +esac +AC_SUBST(PCAP_SUPPORT_NETFILTER) +AC_SUBST(NETFILTER_SRC) + AC_ARG_ENABLE([bluetooth], [AC_HELP_STRING([--enable-bluetooth],[enable Bluetooth support @<:@default=yes, if support available@:>@])], ,enable_bluetooth=yes) diff --git a/pcap-linux.c b/pcap-linux.c index fa1d028d..a70d585f 100644 --- a/pcap-linux.c +++ b/pcap-linux.c @@ -199,6 +199,11 @@ static const char rcsid[] _U_ = #include "pcap-can-linux.h" #endif +#ifdef PCAP_SUPPORT_NETFILTER +int netfilter_platform_finddevs(pcap_if_t **alldevsp, char *err_str); +pcap_t *nflog_create(const char *device, char *ebuf); +#endif + /* * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET * sockets rather than SOCK_PACKET sockets. @@ -419,6 +424,12 @@ pcap_create(const char *device, char *ebuf) } #endif +#ifdef PCAP_SUPPORT_NETFILTER + if (strncmp(device, "nflog", strlen("nflog")) == 0) { + return nflog_create(device, ebuf); + } +#endif + handle = pcap_create_common(device, ebuf); if (handle == NULL) return NULL; @@ -2199,6 +2210,14 @@ pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) return (-1); #endif +#ifdef PCAP_SUPPORT_NETFILTER + /* + * Add netfilter devices. + */ + if (netfilter_platform_finddevs(alldevsp, errbuf) < 0) + return (-1); +#endif + return (0); } diff --git a/pcap-netfilter-linux.c b/pcap-netfilter-linux.c new file mode 100644 index 00000000..d55b5c35 --- /dev/null +++ b/pcap-netfilter-linux.c @@ -0,0 +1,443 @@ +/* + * Copyright (c) 2011 Jakub Zawadzki + * 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 COPYRIGHT HOLDERS AND CONTRIBUTORS + * "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 COPYRIGHT + * OWNER OR CONTRIBUTORS 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. + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "pcap-int.h" + +#ifdef NEED_STRERROR_H +#include "strerror.h" +#endif + +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#include +#include +#include + +#define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) + +#define NFLOG_IFACE "nflog" + +static int +nflog_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) +{ + const unsigned char *buf; + int count = 0; + int len; + + /* ignore interrupt system call error */ + do { + len = recv(handle->fd, handle->buffer, handle->bufsize, 0); + if (handle->break_loop) { + handle->break_loop = 0; + return -2; + } + } while ((len == -1) && (errno == EINTR)); + + if (len < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno)); + return -1; + } + + buf = handle->buffer; + while (len >= NLMSG_SPACE(0)) { + const struct nlmsghdr *nlh = (const struct nlmsghdr *) buf; + u_int32_t msg_len; + + if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || len < nlh->nlmsg_len) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); + return -1; + } + + if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && + NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) + { + const struct nfattr *payload_attr = NULL; + + if (nlh->nlmsg_len < HDR_LENGTH) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); + return -1; + } + + if (nlh->nlmsg_len > HDR_LENGTH) { + struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh)); + int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); + + while (NFA_OK(attr, attr_len)) { + switch (NFA_TYPE(attr)) { + case NFULA_PAYLOAD: + payload_attr = attr; + break; + } + attr = NFA_NEXT(attr, attr_len); + } + } + + if (payload_attr) { + struct pcap_pkthdr pkth; + + const unsigned char *payload = NFA_DATA(payload_attr); + int payload_len = NFA_PAYLOAD(payload_attr); + + pkth.len = pkth.caplen = payload_len; + /* pkth.caplen = min (payload_len, handle->snapshot); */ + + gettimeofday(&pkth.ts, NULL); + if (handle->fcode.bf_insns == NULL || + bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) + { + handle->md.packets_read++; + callback(user, &pkth, payload); + count++; + } + } + } + + msg_len = NLMSG_ALIGN(nlh->nlmsg_len); + if (msg_len > len) + msg_len = len; + + len -= msg_len; + buf += msg_len; + } + return count; +} + +static int +netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) +{ + stats->ps_recv = handle->md.packets_read; + stats->ps_drop = 0; + stats->ps_ifdrop = 0; + return 0; +} + +static int +netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size) +{ + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices"); + return (-1); +} + +struct my_nfattr { + u_int16_t nfa_len; + u_int16_t nfa_type; + void *data; +}; + +static int +nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa) +{ + char buf[1024] __attribute__ ((aligned)); + + struct nlmsghdr *nlh = (struct nlmsghdr *) buf; + struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); + + struct sockaddr_nl snl; + static unsigned int seq_id; + + if (!seq_id) + seq_id = time(NULL); + ++seq_id; + + nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); + nlh->nlmsg_type = (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG; + nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK; + nlh->nlmsg_pid = 0; /* to kernel */ + nlh->nlmsg_seq = seq_id; + + nfg->nfgen_family = family; + nfg->version = NFNETLINK_V0; + nfg->res_id = htons(res_id); + + if (mynfa) { + struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); + + nfa->nfa_type = mynfa->nfa_type; + nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); + memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); + nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); + } + + memset(&snl, 0, sizeof(snl)); + snl.nl_family = AF_NETLINK; + + if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) + return -1; + + /* waiting for reply loop */ + do { + socklen_t addrlen = sizeof(snl); + int len; + + /* ignore interrupt system call error */ + do { + len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); + } while ((len == -1) && (errno == EINTR)); + + if (len <= 0) + return len; + + if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { + errno = EINVAL; + return -1; + } + + nlh = (struct nlmsghdr *) buf; + if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ + continue; + + while (len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) { + if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { + if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { + errno = EBADMSG; + return -1; + } + errno = -(*((int *)NLMSG_DATA(nlh))); + return (errno == 0) ? 0 : -1; + } + nlh = NLMSG_NEXT(nlh, len); + } + } while (1); + + return -1; /* never here */ +} + +static int +nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family) +{ + struct nfulnl_msg_config_cmd msg; + struct my_nfattr nfa; + + msg.command = cmd; + + nfa.data = &msg; + nfa.nfa_type = NFULA_CFG_CMD; + nfa.nfa_len = sizeof(msg); + + return nflog_send_config_msg(handle, family, group_id, &nfa); +} + +static int +nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) +{ + struct nfulnl_msg_config_mode msg; + struct my_nfattr nfa; + + msg.copy_range = htonl(copy_range); + msg.copy_mode = copy_mode; + + nfa.data = &msg; + nfa.nfa_type = NFULA_CFG_MODE; + nfa.nfa_len = sizeof(msg); + + return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); +} + +static int +nflog_activate(pcap_t* handle) +{ + const char *dev = handle->opt.source; + unsigned short groups[32]; + int group_count = 0; + int i; + + if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { + dev += strlen(NFLOG_IFACE); + + /* nflog:30,33,42 looks nice, allow it */ + if (*dev == ':') + dev++; + + while (*dev) { + long int group_id; + char *end_dev; + + if (group_count == 32) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Maximum 32 netfilter groups! dev: %s", + handle->opt.source); + return PCAP_ERROR; + } + + group_id = strtol(dev, &end_dev, 0); + if (end_dev != dev) { + if (group_id < 0 || group_id > 65535) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Netfilter group range from 0 to 65535 (got %ld)", + group_id); + return PCAP_ERROR; + } + + groups[group_count++] = (unsigned short) group_id; + dev = end_dev; + } + if (*dev != ',') + break; + dev++; + } + } + + if (*dev) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Can't get netfilter group(s) index from %s", + handle->opt.source); + return PCAP_ERROR; + } + + /* if no groups, add default: 0 */ + if (!group_count) { + groups[0] = 0; + group_count = 1; + } + + /* Initialize some components of the pcap structure. */ + handle->bufsize = 128 + handle->snapshot; + handle->offset = 0; + handle->linktype = DLT_IPV4; + handle->read_op = nflog_read_linux; + handle->inject_op = netfilter_inject_linux; + handle->setfilter_op = install_bpf_program; /* no kernel filtering */ + handle->setdirection_op = NULL; + handle->set_datalink_op = NULL; + handle->getnonblock_op = pcap_getnonblock_fd; + handle->setnonblock_op = pcap_setnonblock_fd; + handle->stats_op = netfilter_stats_linux; + + /* Create netlink socket */ + handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); + if (handle->fd < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno)); + return PCAP_ERROR; + } + + handle->buffer = malloc(handle->bufsize); + if (!handle->buffer) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno)); + goto close_fail; + } + + if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); + goto close_fail; + } + + if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); + goto close_fail; + } + + /* Bind socket to the nflog groups */ + for (i = 0; i < group_count; i++) { + if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); + goto close_fail; + } + + if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno)); + goto close_fail; + } + } + + if (handle->opt.rfmon) { + /* + * Monitor mode doesn't apply to netfilter devices. + */ + pcap_cleanup_live_common(handle); + return PCAP_ERROR_RFMON_NOTSUP; + } + + if (handle->opt.buffer_size != 0) { + /* + * Set the socket buffer size to the specified value. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno)); + goto close_fail; + } + } + + handle->selectable_fd = handle->fd; + return 0; + +close_fail: + pcap_cleanup_live_common(handle); + return PCAP_ERROR; +} + +pcap_t * +nflog_create(const char *device, char *ebuf) +{ + pcap_t *p; + + p = pcap_create_common(device, ebuf); + if (p == NULL) + return (NULL); + + p->activate_op = nflog_activate; + return (p); +} + +int +netfilter_platform_finddevs(pcap_if_t **alldevsp, char *err_str) +{ + pcap_if_t *found_dev = *alldevsp; + int sock; + + sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); + if (sock < 0) { + /* if netlink is not supported this this is not fatal */ + if (errno == EAFNOSUPPORT) + return 0; + snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s", + errno, pcap_strerror(errno)); + return -1; + } + close(sock); + + if (pcap_add_if(&found_dev, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) < 0) + return -1; + return 0; +} +