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netfilter: conntrack: fix vtag checks for ABORT/SHUTDOWN_COMPLETE

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RFC 9260, Sec 8.5.1 states that for ABORT/SHUTDOWN_COMPLETE, the chunk
MUST be accepted if the vtag of the packet matches its own tag and the
T bit is not set OR if it is set to its peer's vtag and the T bit is set
in chunk flags. Otherwise the packet MUST be silently dropped.

Update vtag verification for ABORT/SHUTDOWN_COMPLETE based on the above
description.

Fixes: 9fb9cbb108 ("[NETFILTER]: Add nf_conntrack subsystem.")
Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Sriram Yagnaraman 2023-01-24 02:47:18 +01:00 committed by Pablo Neira Ayuso
parent 208a21107e
commit a9993591fa
1 changed files with 16 additions and 9 deletions
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25
net/netfilter/nf_conntrack_proto_sctp.c
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@ -424,22 +424,29 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
/* Special cases of Verification tag check (Sec 8.5.1) */
if (sch->type == SCTP_CID_INIT) {
/* Sec 8.5.1 (A) */
/* (A) vtag MUST be zero */
if (sh->vtag != 0)
goto out_unlock;
} else if (sch->type == SCTP_CID_ABORT) {
/* Sec 8.5.1 (B) */
if (sh->vtag != ct->proto.sctp.vtag[dir] &&
sh->vtag != ct->proto.sctp.vtag[!dir])
/* (B) vtag MUST match own vtag if T flag is unset OR
* MUST match peer's vtag if T flag is set
*/
if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
sh->vtag != ct->proto.sctp.vtag[dir]) ||
((sch->flags & SCTP_CHUNK_FLAG_T) &&
sh->vtag != ct->proto.sctp.vtag[!dir]))
goto out_unlock;
} else if (sch->type == SCTP_CID_SHUTDOWN_COMPLETE) {
/* Sec 8.5.1 (C) */
if (sh->vtag != ct->proto.sctp.vtag[dir] &&
sh->vtag != ct->proto.sctp.vtag[!dir] &&
sch->flags & SCTP_CHUNK_FLAG_T)
/* (C) vtag MUST match own vtag if T flag is unset OR
* MUST match peer's vtag if T flag is set
*/
if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
sh->vtag != ct->proto.sctp.vtag[dir]) ||
((sch->flags & SCTP_CHUNK_FLAG_T) &&
sh->vtag != ct->proto.sctp.vtag[!dir]))
goto out_unlock;
} else if (sch->type == SCTP_CID_COOKIE_ECHO) {
/* Sec 8.5.1 (D) */
/* (D) vtag must be same as init_vtag as found in INIT_ACK */
if (sh->vtag != ct->proto.sctp.vtag[dir])
goto out_unlock;
} else if (sch->type == SCTP_CID_HEARTBEAT) {