Bounds-check the individual components of a SAP reply.

[tcpdump] / print-icmp.c

diff --git a/print-icmp.c b/print-icmp.c
index 09b94618e08415208d0734fd643e29595acf1f58..862b095a1fc15a3c1efc847a16bf6433ba02bbfa 100644 (file)
--- a/print-icmp.c
+++ b/print-icmp.c
@@ -21,7 +21,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-icmp.c,v 1.77 2004-06-14 15:08:08 hannes Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-icmp.c,v 1.81 2005-04-06 21:32:40 mcr Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -107,6 +107,7 @@ struct icmp {
 };
 
 #define ICMP_MPLS_EXT_EXTRACT_VERSION(x) (((x)&0xf0)>>4) 
+#define ICMP_MPLS_EXT_VERSION 2
 
 /*
  * Lower bounds on packet lengths for various types.
@@ -171,6 +172,8 @@ struct icmp {
        (type) == ICMP_TSTAMP || (type) == ICMP_TSTAMPREPLY || \
        (type) == ICMP_IREQ || (type) == ICMP_IREQREPLY || \
        (type) == ICMP_MASKREQ || (type) == ICMP_MASKREPLY)
+#define        ICMP_MPLS_EXT_TYPE(type) \
+       ((type) == ICMP_UNREACH || (type) == ICMP_TIMXCEED)
 /* rfc1700 */
 #ifndef ICMP_UNREACH_NET_UNKNOWN
 #define ICMP_UNREACH_NET_UNKNOWN       6       /* destination net unknown */
@@ -524,22 +527,35 @@ icmp_print(const u_char *bp, u_int plen, const u_char *bp2, int fragmented)
                (void)printf("\n\t");
                ip = (struct ip *)bp;
                snaplen = snapend - bp;
-               ip_print(bp, EXTRACT_16BITS(&ip->ip_len));
+               ip_print(gndo, bp, EXTRACT_16BITS(&ip->ip_len));
        }
 
-        if (vflag >= 1 && plen > ICMP_EXTD_MINLEN) {
+        if (vflag >= 1 && plen > ICMP_EXTD_MINLEN && ICMP_MPLS_EXT_TYPE(dp->icmp_type)) {
+
+            TCHECK(*(dp->icmp_mpls_ext_version));
+            printf("\n\tMPLS extension v%u",ICMP_MPLS_EXT_EXTRACT_VERSION(*(dp->icmp_mpls_ext_version)));
+            
+            /*
+             * Sanity checking of the header.
+             */
+            if (ICMP_MPLS_EXT_EXTRACT_VERSION(*(dp->icmp_mpls_ext_version)) != ICMP_MPLS_EXT_VERSION) {
+                printf(" packet not supported");
+                return;
+            }
+
             hlen = plen - ICMP_EXTD_MINLEN;
-            printf("\n\tMPLS extension v%u, checksum 0x%04x (unverified), length %u", /* FIXME */
-                   ICMP_MPLS_EXT_EXTRACT_VERSION(*(dp->icmp_mpls_ext_version)),
+            TCHECK2(*(dp->icmp_mpls_ext_checksum), 2);
+            printf(", checksum 0x%04x (unverified), length %u", /* FIXME */
                    EXTRACT_16BITS(dp->icmp_mpls_ext_checksum),
                    hlen);
-            hlen -= 4; /* subtract common header size */
 
+            hlen -= 4; /* subtract common header size */
             obj_tptr = (u_int8_t *)dp->icmp_mpls_ext_data;
 
             while (hlen > sizeof(struct icmp_mpls_ext_object_header_t)) {
 
                 icmp_mpls_ext_object_header = (struct icmp_mpls_ext_object_header_t *)obj_tptr;
+                TCHECK(*icmp_mpls_ext_object_header);
                 obj_tlen = EXTRACT_16BITS(icmp_mpls_ext_object_header->length);
                 obj_class_num = icmp_mpls_ext_object_header->class_num;
                 obj_ctype = icmp_mpls_ext_object_header->ctype;
@@ -552,12 +568,15 @@ icmp_print(const u_char *bp, u_int plen, const u_char *bp2, int fragmented)
                        obj_tlen);
 
                 hlen-=sizeof(struct icmp_mpls_ext_object_header_t); /* length field includes tlv header */
-                obj_tlen-=sizeof(struct icmp_mpls_ext_object_header_t); 
+                if (obj_tlen < sizeof(struct icmp_mpls_ext_object_header_t))
+                    break;
+                obj_tlen-=sizeof(struct icmp_mpls_ext_object_header_t);
 
                 switch (obj_class_num) {
                 case 1:
                     switch(obj_ctype) {
                     case 1:
+                        TCHECK2(*obj_tptr, 4);
                         raw_label = EXTRACT_32BITS(obj_tptr);
                         printf("\n\t    label %u, exp %u", MPLS_LABEL(raw_label), MPLS_EXP(raw_label));
                         if (MPLS_STACK(raw_label))
@@ -578,6 +597,8 @@ icmp_print(const u_char *bp, u_int plen, const u_char *bp2, int fragmented)
                     print_unknown_data(obj_tptr, "\n\t    ", obj_tlen);
                     break;
                 }
+                if (hlen < obj_tlen)
+                    break;
                 hlen -= obj_tlen;
                 obj_tptr += obj_tlen;
             }