Commit 9ed973cc40c588abeaa58aea0683ea665132d11d
Committed by
David S. Miller
David S. Miller
1 parent
c3f9b01849
Exists in
master
and in
16 other branches
bridge: multicast: add sanity check for general query destination
General IGMP and MLD queries are supposed to have the multicast link-local all-nodes address as their destination according to RFC2236 section 9, RFC3376 section 4.1.12/9.1, RFC2710 section 8 and RFC3810 section 5.1.15. Without this check, such malformed IGMP/MLD queries can result in a denial of service: The queries are ignored by most IGMP/MLD listeners therefore they will not respond with an IGMP/MLD report. However, without this patch these malformed MLD queries would enable the snooping part in the bridge code, potentially shutting down the according ports towards these hosts for multicast traffic as the bridge did not learn about these listeners. Reported-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Linus Lüssing <linus.luessing@web.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Showing 1 changed file with 19 additions and 0 deletions Side-by-side Diff
net/bridge/br_multicast.c
| ... | ... | @@ -1181,6 +1181,14 @@ |
| 1181 | 1181 | IGMPV3_MRC(ih3->code) * (HZ / IGMP_TIMER_SCALE) : 1; |
| 1182 | 1182 | } |
| 1183 | 1183 | |
| 1184 | + /* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer | |
| 1185 | + * all-systems destination addresses (224.0.0.1) for general queries | |
| 1186 | + */ | |
| 1187 | + if (!group && iph->daddr != htonl(INADDR_ALLHOSTS_GROUP)) { | |
| 1188 | + err = -EINVAL; | |
| 1189 | + goto out; | |
| 1190 | + } | |
| 1191 | + | |
| 1184 | 1192 | br_multicast_query_received(br, port, &br->ip4_querier, !!iph->saddr, |
| 1185 | 1193 | max_delay); |
| 1186 | 1194 | |
| ... | ... | @@ -1228,6 +1236,7 @@ |
| 1228 | 1236 | unsigned long max_delay; |
| 1229 | 1237 | unsigned long now = jiffies; |
| 1230 | 1238 | const struct in6_addr *group = NULL; |
| 1239 | + bool is_general_query; | |
| 1231 | 1240 | int err = 0; |
| 1232 | 1241 | |
| 1233 | 1242 | spin_lock(&br->multicast_lock); |
| ... | ... | @@ -1260,6 +1269,16 @@ |
| 1260 | 1269 | group = &mld2q->mld2q_mca; |
| 1261 | 1270 | |
| 1262 | 1271 | max_delay = max(msecs_to_jiffies(mldv2_mrc(mld2q)), 1UL); |
| 1272 | + } | |
| 1273 | + | |
| 1274 | + is_general_query = group && ipv6_addr_any(group); | |
| 1275 | + | |
| 1276 | + /* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer | |
| 1277 | + * all-nodes destination address (ff02::1) for general queries | |
| 1278 | + */ | |
| 1279 | + if (is_general_query && !ipv6_addr_is_ll_all_nodes(&ip6h->daddr)) { | |
| 1280 | + err = -EINVAL; | |
| 1281 | + goto out; | |
| 1263 | 1282 | } |
| 1264 | 1283 | |
| 1265 | 1284 | br_multicast_query_received(br, port, &br->ip6_querier, |