X-Git-Url: https://git.tcpdump.org/libpcap/blobdiff_plain/02d818ad909ad9f975bc2ef19491f76c476063ca..f6fb59b11d20222d4648cdceeaadf6ce971a7a9a:/pcap-netfilter-linux.c diff --git a/pcap-netfilter-linux.c b/pcap-netfilter-linux.c index 85899559..33204a54 100644 --- a/pcap-netfilter-linux.c +++ b/pcap-netfilter-linux.c @@ -33,6 +33,7 @@ #endif #include "pcap-int.h" +#include "diag-control.h" #ifdef NEED_STRERROR_H #include "strerror.h" @@ -56,13 +57,13 @@ #include #include -/* NOTE: if your program drops privilages after pcap_activate() it WON'T work with nfqueue. +/* NOTE: if your program drops privileges after pcap_activate() it WON'T work with nfqueue. * It took me quite some time to debug ;/ * - * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privilages, + * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges, * and in nfqueue we need to send verdict reply after recving packet. * - * In tcpdump you can disable dropping privilages with -Z root + * In tcpdump you can disable dropping privileges with -Z root */ #include "pcap-netfilter-linux.h" @@ -82,7 +83,7 @@ struct pcap_netfilter { u_int packets_nobufs; /* ENOBUFS counter */ }; -static int nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict); +static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict); static int @@ -91,7 +92,7 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c struct pcap_netfilter *handlep = handle->priv; register u_char *bp, *ep; int count = 0; - int len; + ssize_t len; /* * Has "pcap_breakloop()" been called? @@ -127,17 +128,25 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c } while ((len == -1) && (errno == EINTR || errno == ENOBUFS)); if (len < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s", errno, pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "Can't receive packet"); return PCAP_ERROR; } bp = (unsigned char *)handle->buffer; } else bp = handle->bp; + + /* + * Loop through each message. + * + * This assumes that a single buffer of message will have + * <= INT_MAX packets, so the message count doesn't overflow. + */ ep = bp + len; while (bp < ep) { const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp; - u_int32_t msg_len; + uint32_t msg_len; nftype_t type = OTHER; /* * Has "pcap_breakloop()" been called? @@ -151,14 +160,25 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c */ if (handle->break_loop) { handle->bp = bp; - handle->cc = ep - bp; + handle->cc = (int)(ep - bp); if (count == 0) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } else return count; } - if (ep - bp < NLMSG_SPACE(0)) { + /* + * NLMSG_SPACE(0) might be signed or might be unsigned, + * depending on whether the kernel defines NLMSG_ALIGNTO + * as 4, which older kernels do, or as 4U, which newer + * kernels do. + * + * ep - bp is of type ptrdiff_t, which is signed. + * + * To squelch warnings, we cast both to size_t, which + * is unsigned; ep >= bp, so the cast is safe. + */ + if ((size_t)(ep - bp) < (size_t)NLMSG_SPACE(0)) { /* * There's less than one netlink message left * in the buffer. Give up. @@ -167,7 +187,7 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c } if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (nlmsg_len: %u)", len, nlh->nlmsg_len); return -1; } @@ -189,7 +209,7 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c const struct nfattr *payload_attr = NULL; if (nlh->nlmsg_len < HDR_LENGTH) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); return -1; } @@ -239,7 +259,7 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c gettimeofday(&pkth.ts, NULL); if (handle->fcode.bf_insns == NULL || - bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) + pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) { handlep->packets_read++; callback(user, &pkth, payload); @@ -261,14 +281,21 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c * If the message length would run past the end of the * buffer, truncate it to the remaining space in the * buffer. + * + * To squelch warnings, we cast ep - bp to uint32_t, which + * is unsigned and is the type of msg_len; ep >= bp, and + * len should fit in 32 bits (either it's set from an int + * or it's set from a recv() call with a buffer size that's + * an int, and we're assuming either ILP32 or LP64), so + * the cast is safe. */ - if (msg_len > ep - bp) - msg_len = ep - bp; + if (msg_len > (uint32_t)(ep - bp)) + msg_len = (uint32_t)(ep - bp); bp += msg_len; if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) { handle->bp = bp; - handle->cc = ep - bp; + handle->cc = (int)(ep - bp); if (handle->cc < 0) handle->cc = 0; return count; @@ -298,22 +325,24 @@ netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) } static int -netfilter_inject_linux(pcap_t *handle, const void *buf, size_t size) +netfilter_inject_linux(pcap_t *handle, const void *buf _U_, int size _U_) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on netfilter devices"); + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Packet injection is not supported on netfilter devices"); return (-1); } struct my_nfattr { - u_int16_t nfa_len; - u_int16_t nfa_type; + uint16_t nfa_len; + uint16_t nfa_type; void *data; }; static int -netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa) +netfilter_send_config_msg(const pcap_t *handle, uint16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa) { char buf[1024] __attribute__ ((aligned)); + memset(buf, 0, sizeof(buf)); struct nlmsghdr *nlh = (struct nlmsghdr *) buf; struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); @@ -322,7 +351,9 @@ netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_i static unsigned int seq_id; if (!seq_id) +DIAG_OFF_NARROWING seq_id = time(NULL); +DIAG_ON_NARROWING ++seq_id; nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); @@ -360,7 +391,11 @@ netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_i /* ignore interrupt system call error */ do { - len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); + /* + * The buffer is not so big that its size won't + * fit into an int. + */ + len = (int)recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); } while ((len == -1) && (errno == EINTR)); if (len <= 0) @@ -375,7 +410,7 @@ netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_i if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ continue; - while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, len)) { + while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)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; @@ -392,13 +427,13 @@ netfilter_send_config_msg(const pcap_t *handle, u_int16_t msg_type, int ack, u_i } static int -nflog_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) +nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) { return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); } static int -nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int8_t family) +nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family) { struct nfulnl_msg_config_cmd msg; struct my_nfattr nfa; @@ -413,7 +448,7 @@ nflog_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_ } 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) +nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) { struct nfulnl_msg_config_mode msg; struct my_nfattr nfa; @@ -429,7 +464,7 @@ nflog_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_m } static int -nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_int32_t verdict) +nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict) { struct nfqnl_msg_verdict_hdr msg; struct my_nfattr nfa; @@ -445,13 +480,13 @@ nfqueue_send_verdict(const pcap_t *handle, u_int16_t group_id, u_int32_t id, u_i } static int -nfqueue_send_config_msg(const pcap_t *handle, u_int8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) +nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) { return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); } static int -nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, u_int16_t pf) +nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf) { struct nfqnl_msg_config_cmd msg; struct my_nfattr nfa; @@ -467,7 +502,7 @@ nfqueue_send_config_cmd(const pcap_t *handle, u_int16_t group_id, u_int8_t cmd, } static int -nfqueue_send_config_mode(const pcap_t *handle, u_int16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) +nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) { struct nfqnl_msg_config_params msg; struct my_nfattr nfa; @@ -507,7 +542,7 @@ netfilter_activate(pcap_t* handle) char *end_dev; if (group_count == 32) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Maximum 32 netfilter groups! dev: %s", handle->opt.device); return PCAP_ERROR; @@ -516,7 +551,7 @@ netfilter_activate(pcap_t* handle) group_id = strtol(dev, &end_dev, 0); if (end_dev != dev) { if (group_id < 0 || group_id > 65535) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Netfilter group range from 0 to 65535 (got %ld)", group_id); return PCAP_ERROR; @@ -532,7 +567,7 @@ netfilter_activate(pcap_t* handle) } if (type == OTHER || *dev) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get netfilter group(s) index from %s", handle->opt.device); return PCAP_ERROR; @@ -570,7 +605,8 @@ netfilter_activate(pcap_t* handle) /* Create netlink socket */ handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); if (handle->fd < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s", errno, pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't create raw socket"); return PCAP_ERROR; } @@ -588,54 +624,68 @@ netfilter_activate(pcap_t* handle) handle->buffer = malloc(handle->bufsize); if (!handle->buffer) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't allocate dump buffer"); goto close_fail; } if (type == NFLOG) { if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFULNL_CFG_CMD_PF_UNBIND"); goto close_fail; } if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND"); 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) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "Can't listen on group index"); goto close_fail; } if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFULNL_COPY_PACKET: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFULNL_COPY_PACKET"); goto close_fail; } } } else { if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_UNBIND: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND"); goto close_fail; } if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_CFG_CMD_PF_BIND: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND"); goto close_fail; } /* Bind socket to the nfqueue groups */ for (i = 0; i < group_count; i++) { if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't listen on group group index: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "Can't listen on group index"); goto close_fail; } if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "NFQNL_COPY_PACKET: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFQNL_COPY_PACKET"); goto close_fail; } } @@ -654,7 +704,8 @@ netfilter_activate(pcap_t* handle) * 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) { - pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF"); goto close_fail; } } @@ -702,7 +753,7 @@ netfilter_create(const char *device, char *ebuf, int *is_ours) /* OK, it's probably ours. */ *is_ours = 1; - p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter)); + p = PCAP_CREATE_COMMON(ebuf, struct pcap_netfilter); if (p == NULL) return (NULL); @@ -720,15 +771,23 @@ netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str) /* if netlink is not supported this is not fatal */ if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) return 0; - pcap_snprintf(err_str, PCAP_ERRBUF_SIZE, "Can't open netlink socket %d:%s", - errno, pcap_strerror(errno)); + pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE, + errno, "Can't open netlink socket"); return -1; } close(sock); - if (add_dev(devlistp, NFLOG_IFACE, 0, "Linux netfilter log (NFLOG) interface", err_str) == NULL) + /* + * The notion of "connected" vs. "disconnected" doesn't apply. + * XXX - what about "up" and "running"? + */ + if (add_dev(devlistp, NFLOG_IFACE, + PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, + "Linux netfilter log (NFLOG) interface", err_str) == NULL) return -1; - if (add_dev(devlistp, NFQUEUE_IFACE, 0, "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL) + if (add_dev(devlistp, NFQUEUE_IFACE, + PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, + "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL) return -1; return 0; }