Merge branch 'master' into pcap-options

[libpcap] / pcap-netfilter-linux.c

diff --git a/pcap-netfilter-linux.c b/pcap-netfilter-linux.c
index cf0e2560e2e80c9eb1812225fc4c0f396a3a2fa7..33204a54e045bed86b69928f586cfb9c1ca66b10 100644 (file)
--- 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 <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,
+ *       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"
@@ -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.
@@ -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));
@@ -620,7 +648,7 @@ netfilter_activate(pcap_t* handle)
                        if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
                                pcap_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;
                        }
 
@@ -650,7 +678,7 @@ netfilter_activate(pcap_t* handle)
                        if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) {
                                pcap_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;
                        }
 
@@ -725,7 +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);