[PATCH] sctp: Fix sending when PMTU is less than SCTP_DEFAULT_MINSEGMENT
From: Petr Malat <hidden>
Date: 2020-11-05 10:42:33
Also in:
linux-sctp, lkml
Subsystem:
networking [general], sctp protocol, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Marcelo Ricardo Leitner, Xin Long, Linus Torvalds
Function sctp_dst_mtu() never returns lower MTU than SCTP_TRUNC4(SCTP_DEFAULT_MINSEGMENT) even when the actual MTU is less, in which case we rely on the IP fragmentation and must enable it. Signed-off-by: Petr Malat <redacted> --- net/sctp/output.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 1441eaf460bb..87a96cf6bfa4 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c@@ -552,6 +552,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) struct sk_buff *head; struct sctphdr *sh; struct sock *sk; + u32 pmtu; pr_debug("%s: packet:%p\n", __func__, packet); if (list_empty(&packet->chunk_list))
@@ -559,6 +560,13 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); sk = chunk->skb->sk; + /* Fragmentation on the IP level if the actual PMTU could be less + * than SCTP_DEFAULT_MINSEGMENT. See sctp_dst_mtu(). + */ + pmtu = tp->asoc ? tp->asoc->pathmtu : tp->pathmtu; + if (pmtu <= SCTP_DEFAULT_MINSEGMENT) + packet->ipfragok = 1; + /* check gso */ if (packet->size > tp->pathmtu && !packet->ipfragok) { if (!sk_can_gso(sk)) {
--
2.20.1