If an sctp connection gets re-used, heartbeats are flagged as invalid
because their vtag doesn't match.
Handle this in a similar way as TCP conntrack when it suspects that the
endpoints and conntrack are out-of-sync.
When a HEARTBEAT request fails its vtag validation, flag this in the
conntrack state and accept the packet.
When a HEARTBEAT_ACK is received with an invalid vtag in the reverse
direction after we allowed such a HEARTBEAT through, assume we are
out-of-sync and re-set the vtag info.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
include/linux/netfilter/nf_conntrack_sctp.h | 2 +
net/netfilter/nf_conntrack_proto_sctp.c | 43 ++++++++++++++++++---
2 files changed, 39 insertions(+), 6 deletions(-)
diff --git a/include/linux/netfilter/nf_conntrack_sctp.h b/include/linux/netfilter/nf_conntrack_sctp.h
index 9a33f171aa82..625f491b95de 100644
--- a/include/linux/netfilter/nf_conntrack_sctp.h
+++ b/include/linux/netfilter/nf_conntrack_sctp.h
@@ -9,6 +9,8 @@ struct ip_ct_sctp {
enum sctp_conntrack state;
__be32 vtag[IP_CT_DIR_MAX];
+ u8 last_dir;
+ u8 flags;
};
#endif /* _NF_CONNTRACK_SCTP_H */
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index 4f897b14b606..8b8b9ca61eef 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -62,6 +62,8 @@ static const unsigned int sctp_timeouts[SCTP_CONNTRACK_MAX] = {
[SCTP_CONNTRACK_HEARTBEAT_ACKED] = 210 SECS,
};
+#define SCTP_FLAG_HEARTBEAT_VTAG_FAILED 1
+
#define sNO SCTP_CONNTRACK_NONE
#define sCL SCTP_CONNTRACK_CLOSED
#define sCW SCTP_CONNTRACK_COOKIE_WAIT
@@ -369,6 +371,7 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
u_int32_t offset, count;
unsigned int *timeouts;
unsigned long map[256 / sizeof(unsigned long)] = { 0 };
+ bool ignore = false;
if (sctp_error(skb, dataoff, state))
return -NF_ACCEPT;
@@ -404,8 +407,9 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
goto out;
}
- old_state = new_state = SCTP_CONNTRACK_NONE;
spin_lock_bh(&ct->lock);
+
+ old_state = ct->proto.sctp.state;
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) {
@@ -427,19 +431,42 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
/* Sec 8.5.1 (D) */
if (sh->vtag != ct->proto.sctp.vtag[dir])
goto out_unlock;
- } else if (sch->type == SCTP_CID_HEARTBEAT ||
- sch->type == SCTP_CID_HEARTBEAT_ACK) {
+ } else if (sch->type == SCTP_CID_HEARTBEAT) {
+ if (ct->proto.sctp.vtag[dir] == 0) {
+ pr_debug("Setting %d vtag %x for dir %d\n", sch->type, sh->vtag, dir);
+ ct->proto.sctp.vtag[dir] = sh->vtag;
+ } else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
+ if (test_bit(SCTP_CID_DATA, map) || ignore)
+ goto out_unlock;
+
+ ct->proto.sctp.flags |= SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
+ ct->proto.sctp.last_dir = dir;
+ ignore = true;
+ continue;
+ } else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
+ ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
+ }
+ } else if (sch->type == SCTP_CID_HEARTBEAT_ACK) {
if (ct->proto.sctp.vtag[dir] == 0) {
pr_debug("Setting vtag %x for dir %d\n",
sh->vtag, dir);
ct->proto.sctp.vtag[dir] = sh->vtag;
} else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
- pr_debug("Verification tag check failed\n");
- goto out_unlock;
+ if (test_bit(SCTP_CID_DATA, map) || ignore)
+ goto out_unlock;
+
+ if ((ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) == 0 ||
+ ct->proto.sctp.last_dir == dir)
+ goto out_unlock;
+
+ ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
+ ct->proto.sctp.vtag[dir] = sh->vtag;
+ ct->proto.sctp.vtag[!dir] = 0;
+ } else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
+ ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
}
}
- old_state = ct->proto.sctp.state;
new_state = sctp_new_state(dir, old_state, sch->type);
/* Invalid */
@@ -470,6 +497,10 @@ int nf_conntrack_sctp_packet(struct nf_conn *ct,
}
spin_unlock_bh(&ct->lock);
+ /* allow but do not refresh timeout */
+ if (ignore)
+ return NF_ACCEPT;
+
timeouts = nf_ct_timeout_lookup(ct);
if (!timeouts)
timeouts = nf_sctp_pernet(nf_ct_net(ct))->timeouts;
--
2.26.2
