]> The Tcpdump Group git mirrors - libpcap/blobdiff - pcap-netfilter-linux.c
Merge pull request #1229 from guyharris/more-pcap-to-pcapint
[libpcap] / pcap-netfilter-linux.c
index cf0e2560e2e80c9eb1812225fc4c0f396a3a2fa7..7b6e99884c4d5617cf9f308bf3735eba6feb6154 100644 (file)
@@ -33,6 +33,7 @@
 #endif
 
 #include "pcap-int.h"
+#include "diag-control.h"
 
 #ifdef NEED_STRERROR_H
 #include "strerror.h"
 #include <linux/netfilter/nfnetlink_log.h>
 #include <linux/netfilter/nfnetlink_queue.h>
 
-/* 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,
- *       and in nfqueue we need to send verdict reply after recving packet.
+ *       Sending any data to nfnetlink socket requires CAP_NET_ADMIN privileges,
+ *       and in nfqueue we need to send verdict reply after receiving 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"
@@ -122,12 +123,12 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c
                                handle->break_loop = 0;
                                return PCAP_ERROR_BREAK;
                        }
-                       if (errno == ENOBUFS)
+                       if (len == -1 && errno == ENOBUFS)
                                handlep->packets_nobufs++;
                } while ((len == -1) && (errno == EINTR || errno == ENOBUFS));
 
                if (len < 0) {
-                       pcap_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_fmt_errmsg_for_errno(handle->errbuf,
                            PCAP_ERRBUF_SIZE, errno, "Can't receive packet");
                        return PCAP_ERROR;
                }
@@ -135,6 +136,13 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c
                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;
@@ -159,7 +167,18 @@ netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_c
                        } 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.
@@ -240,7 +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 ||
-                                               pcap_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
+                                               pcapint_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen))
                                {
                                        handlep->packets_read++;
                                        callback(user, &pkth, payload);
@@ -262,8 +281,15 @@ 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)
+               if (msg_len > (uint32_t)(ep - bp))
                        msg_len = (uint32_t)(ep - bp);
 
                bp += msg_len;
@@ -325,7 +351,9 @@ netfilter_send_config_msg(const pcap_t *handle, uint16_t msg_type, int ack, u_in
        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));
@@ -498,8 +526,8 @@ netfilter_activate(pcap_t* handle)
        nftype_t type = OTHER;
        int i;
 
-       if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
-               dev += strlen(NFLOG_IFACE);
+       if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) {
+               dev += strlen(NFLOG_IFACE);
                type = NFLOG;
 
        } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) {
@@ -567,17 +595,17 @@ netfilter_activate(pcap_t* handle)
        handle->offset = 0;
        handle->read_op = netfilter_read_linux;
        handle->inject_op = netfilter_inject_linux;
-       handle->setfilter_op = install_bpf_program; /* no kernel filtering */
+       handle->setfilter_op = pcapint_install_bpf_program; /* no kernel filtering */
        handle->setdirection_op = NULL;
        handle->set_datalink_op = netfilter_set_datalink;
-       handle->getnonblock_op = pcap_getnonblock_fd;
-       handle->setnonblock_op = pcap_setnonblock_fd;
+       handle->getnonblock_op = pcapint_getnonblock_fd;
+       handle->setnonblock_op = pcapint_setnonblock_fd;
        handle->stats_op = netfilter_stats_linux;
 
        /* Create netlink socket */
        handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER);
        if (handle->fd < 0) {
-               pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
+               pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
                    errno, "Can't create raw socket");
                return PCAP_ERROR;
        }
@@ -585,32 +613,35 @@ netfilter_activate(pcap_t* handle)
        if (type == NFLOG) {
                handle->linktype = DLT_NFLOG;
                handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
-               if (handle->dlt_list != NULL) {
-                       handle->dlt_list[0] = DLT_NFLOG;
-                       handle->dlt_list[1] = DLT_IPV4;
-                       handle->dlt_count = 2;
+               if (handle->dlt_list == NULL) {
+                       pcapint_fmt_errmsg_for_errno(handle->errbuf,
+                           PCAP_ERRBUF_SIZE, errno,
+                           "Can't allocate DLT list");
+                       goto close_fail;
                }
-
+               handle->dlt_list[0] = DLT_NFLOG;
+               handle->dlt_list[1] = DLT_IPV4;
+               handle->dlt_count = 2;
        } else
                handle->linktype = DLT_IPV4;
 
        handle->buffer = malloc(handle->bufsize);
        if (!handle->buffer) {
-               pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
+               pcapint_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_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_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_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_fmt_errmsg_for_errno(handle->errbuf,
                            PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND");
                        goto close_fail;
                }
@@ -618,14 +649,14 @@ netfilter_activate(pcap_t* handle)
                /* 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_fmt_errmsg_for_errno(handle->errbuf,
+                               pcapint_fmt_errmsg_for_errno(handle->errbuf,
                                    PCAP_ERRBUF_SIZE, errno,
-                                   "Can't listen on group group index");
+                                   "Can't listen on group index");
                                goto close_fail;
                        }
 
                        if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) {
-                               pcap_fmt_errmsg_for_errno(handle->errbuf,
+                               pcapint_fmt_errmsg_for_errno(handle->errbuf,
                                    PCAP_ERRBUF_SIZE, errno,
                                    "NFULNL_COPY_PACKET");
                                goto close_fail;
@@ -634,13 +665,13 @@ netfilter_activate(pcap_t* handle)
 
        } else {
                if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) {
-                       pcap_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_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_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_fmt_errmsg_for_errno(handle->errbuf,
                            PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND");
                        goto close_fail;
                }
@@ -648,14 +679,14 @@ netfilter_activate(pcap_t* handle)
                /* 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_fmt_errmsg_for_errno(handle->errbuf,
+                               pcapint_fmt_errmsg_for_errno(handle->errbuf,
                                    PCAP_ERRBUF_SIZE, errno,
-                                   "Can't listen on group group index");
+                                   "Can't listen on group index");
                                goto close_fail;
                        }
 
                        if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) {
-                               pcap_fmt_errmsg_for_errno(handle->errbuf,
+                               pcapint_fmt_errmsg_for_errno(handle->errbuf,
                                    PCAP_ERRBUF_SIZE, errno,
                                    "NFQNL_COPY_PACKET");
                                goto close_fail;
@@ -667,7 +698,7 @@ netfilter_activate(pcap_t* handle)
                /*
                 * Monitor mode doesn't apply to netfilter devices.
                 */
-               pcap_cleanup_live_common(handle);
+               pcapint_cleanup_live_common(handle);
                return PCAP_ERROR_RFMON_NOTSUP;
        }
 
@@ -676,7 +707,7 @@ 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_fmt_errmsg_for_errno(handle->errbuf,
+                       pcapint_fmt_errmsg_for_errno(handle->errbuf,
                            PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF");
                        goto close_fail;
                }
@@ -686,7 +717,7 @@ netfilter_activate(pcap_t* handle)
        return 0;
 
 close_fail:
-       pcap_cleanup_live_common(handle);
+       pcapint_cleanup_live_common(handle);
        return PCAP_ERROR;
 }
 
@@ -725,7 +756,7 @@ 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);
 
@@ -743,7 +774,7 @@ 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_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
+               pcapint_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE,
                    errno, "Can't open netlink socket");
                return -1;
        }
@@ -753,11 +784,11 @@ netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str)
         * The notion of "connected" vs. "disconnected" doesn't apply.
         * XXX - what about "up" and "running"?
         */
-       if (add_dev(devlistp, NFLOG_IFACE,
+       if (pcapint_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,
+       if (pcapint_add_dev(devlistp, NFQUEUE_IFACE,
            PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
            "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL)
                return -1;