Bugged peer implementation can send corrupted DSS options, consistently
hitting a few warning in the data path. Use DEBUG_NET assertions, to
avoid the splat on some builds and handle consistently the error, dumping
related MIBs and performing fallback and/or reset according to the
subflow type.
Fixes: 6771bfd9ee24 ("mptcp: update mptcp ack sequence from work queue")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-1-c6fb8e93e551@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index 38c2efc82b94..ad88bd3c58df 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -32,6 +32,8 @@ static const struct snmp_mib mptcp_snmp_list[] = {
SNMP_MIB_ITEM("MPJoinSynTxBindErr", MPTCP_MIB_JOINSYNTXBINDERR),
SNMP_MIB_ITEM("MPJoinSynTxConnectErr", MPTCP_MIB_JOINSYNTXCONNECTERR),
SNMP_MIB_ITEM("DSSNotMatching", MPTCP_MIB_DSSNOMATCH),
+ SNMP_MIB_ITEM("DSSCorruptionFallback", MPTCP_MIB_DSSCORRUPTIONFALLBACK),
+ SNMP_MIB_ITEM("DSSCorruptionReset", MPTCP_MIB_DSSCORRUPTIONRESET),
SNMP_MIB_ITEM("InfiniteMapTx", MPTCP_MIB_INFINITEMAPTX),
SNMP_MIB_ITEM("InfiniteMapRx", MPTCP_MIB_INFINITEMAPRX),
SNMP_MIB_ITEM("DSSNoMatchTCP", MPTCP_MIB_DSSTCPMISMATCH),
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index c8ffe18a8722..3206cdda8bb1 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -27,6 +27,8 @@ enum linux_mptcp_mib_field {
MPTCP_MIB_JOINSYNTXBINDERR, /* Not able to bind() the address when sending a SYN + MP_JOIN */
MPTCP_MIB_JOINSYNTXCONNECTERR, /* Not able to connect() when sending a SYN + MP_JOIN */
MPTCP_MIB_DSSNOMATCH, /* Received a new mapping that did not match the previous one */
+ MPTCP_MIB_DSSCORRUPTIONFALLBACK,/* DSS corruption detected, fallback */
+ MPTCP_MIB_DSSCORRUPTIONRESET, /* DSS corruption detected, MPJ subflow reset */
MPTCP_MIB_INFINITEMAPTX, /* Sent an infinite mapping */
MPTCP_MIB_INFINITEMAPRX, /* Received an infinite mapping */
MPTCP_MIB_DSSTCPMISMATCH, /* DSS-mapping did not map with TCP's sequence numbers */
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index c2317919fc14..6d0e201c3eb2 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -620,6 +620,18 @@ static bool mptcp_check_data_fin(struct sock *sk)
return ret;
}
+static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk)
+{
+ if (READ_ONCE(msk->allow_infinite_fallback)) {
+ MPTCP_INC_STATS(sock_net(ssk),
+ MPTCP_MIB_DSSCORRUPTIONFALLBACK);
+ mptcp_do_fallback(ssk);
+ } else {
+ MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET);
+ mptcp_subflow_reset(ssk);
+ }
+}
+
static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
struct sock *ssk,
unsigned int *bytes)
@@ -692,10 +704,16 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
moved += len;
seq += len;
- if (WARN_ON_ONCE(map_remaining < len))
- break;
+ if (unlikely(map_remaining < len)) {
+ DEBUG_NET_WARN_ON_ONCE(1);
+ mptcp_dss_corruption(msk, ssk);
+ }
} else {
- WARN_ON_ONCE(!fin);
+ if (unlikely(!fin)) {
+ DEBUG_NET_WARN_ON_ONCE(1);
+ mptcp_dss_corruption(msk, ssk);
+ }
+
sk_eat_skb(ssk, skb);
done = true;
}
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 1040b3b9696b..e1046a696ab5 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -975,8 +975,10 @@ static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
unsigned int skb_consumed;
skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
- if (WARN_ON_ONCE(skb_consumed >= skb->len))
+ if (unlikely(skb_consumed >= skb->len)) {
+ DEBUG_NET_WARN_ON_ONCE(1);
return true;
+ }
return skb->len - skb_consumed <= subflow->map_data_len -
mptcp_subflow_get_map_offset(subflow);
