From df2729c3238ed89fb8ccf850d38c732858a5bade Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sat, 1 Apr 2017 17:15:59 +0800 Subject: [PATCH] sctp: check for dst and pathmtu update in sctp_packet_config This patch is to move sctp_transport_dst_check into sctp_packet_config from sctp_packet_transmit and add pathmtu check in sctp_packet_config. With this fix, sctp can update dst or pathmtu before appending chunks, which can void dropping packets in sctp_packet_transmit when dst is obsolete or dst's mtu is changed. This patch is also to improve some other codes in sctp_packet_config. It updates packet max_size with gso_max_size, checks for dst and pathmtu, and appends ecne chunk only when packet is empty and asoc is not NULL. It makes sctp flush work better, as we only need to set up them once for one flush schedule. It's also safe, since asoc is NULL only when the packet is created by sctp_ootb_pkt_new in which it just gets the new dst, no need to do more things for it other than set packet with transport's pathmtu. Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller --- include/net/sctp/sctp.h | 17 +++++++++-- net/sctp/output.c | 67 ++++++++++++++++++++++------------------- 2 files changed, 50 insertions(+), 34 deletions(-) diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index 1f71ee5ab518..d75caa7a629b 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -596,12 +596,23 @@ static inline void sctp_v4_map_v6(union sctp_addr *addr) */ static inline struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t) { - if (t->dst && (!dst_check(t->dst, t->dst_cookie) || - t->pathmtu != max_t(size_t, SCTP_TRUNC4(dst_mtu(t->dst)), - SCTP_DEFAULT_MINSEGMENT))) + if (t->dst && !dst_check(t->dst, t->dst_cookie)) sctp_transport_dst_release(t); return t->dst; } +static inline bool sctp_transport_pmtu_check(struct sctp_transport *t) +{ + __u32 pmtu = max_t(size_t, SCTP_TRUNC4(dst_mtu(t->dst)), + SCTP_DEFAULT_MINSEGMENT); + + if (t->pathmtu == pmtu) + return true; + + t->pathmtu = pmtu; + + return false; +} + #endif /* __net_sctp_h__ */ diff --git a/net/sctp/output.c b/net/sctp/output.c index 73fd178007a3..ec4d50a38713 100644 --- a/net/sctp/output.c +++ b/net/sctp/output.c @@ -86,43 +86,53 @@ void sctp_packet_config(struct sctp_packet *packet, __u32 vtag, { struct sctp_transport *tp = packet->transport; struct sctp_association *asoc = tp->asoc; + struct sock *sk; pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag); - packet->vtag = vtag; - if (asoc && tp->dst) { - struct sock *sk = asoc->base.sk; + /* do the following jobs only once for a flush schedule */ + if (!sctp_packet_empty(packet)) + return; - rcu_read_lock(); - if (__sk_dst_get(sk) != tp->dst) { - dst_hold(tp->dst); - sk_setup_caps(sk, tp->dst); - } + /* set packet max_size with pathmtu */ + packet->max_size = tp->pathmtu; + if (!asoc) + return; - if (sk_can_gso(sk)) { - struct net_device *dev = tp->dst->dev; - - packet->max_size = dev->gso_max_size; - } else { - packet->max_size = asoc->pathmtu; - } - rcu_read_unlock(); - - } else { - packet->max_size = tp->pathmtu; + /* update dst or transport pathmtu if in need */ + sk = asoc->base.sk; + if (!sctp_transport_dst_check(tp)) { + sctp_transport_route(tp, NULL, sctp_sk(sk)); + if (asoc->param_flags & SPP_PMTUD_ENABLE) + sctp_assoc_sync_pmtu(sk, asoc); + } else if (!sctp_transport_pmtu_check(tp)) { + if (asoc->param_flags & SPP_PMTUD_ENABLE) + sctp_assoc_sync_pmtu(sk, asoc); } - if (ecn_capable && sctp_packet_empty(packet)) { - struct sctp_chunk *chunk; + /* If there a is a prepend chunk stick it on the list before + * any other chunks get appended. + */ + if (ecn_capable) { + struct sctp_chunk *chunk = sctp_get_ecne_prepend(asoc); - /* If there a is a prepend chunk stick it on the list before - * any other chunks get appended. - */ - chunk = sctp_get_ecne_prepend(asoc); if (chunk) sctp_packet_append_chunk(packet, chunk); } + + if (!tp->dst) + return; + + /* set packet max_size with gso_max_size if gso is enabled*/ + rcu_read_lock(); + if (__sk_dst_get(sk) != tp->dst) { + dst_hold(tp->dst); + sk_setup_caps(sk, tp->dst); + } + packet->max_size = sk_can_gso(sk) ? tp->dst->dev->gso_max_size + : asoc->pathmtu; + rcu_read_unlock(); } /* Initialize the packet structure. */ @@ -582,12 +592,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp) sh->vtag = htonl(packet->vtag); sh->checksum = 0; - /* update dst if in need */ - if (!sctp_transport_dst_check(tp)) { - sctp_transport_route(tp, NULL, sctp_sk(sk)); - if (asoc && asoc->param_flags & SPP_PMTUD_ENABLE) - sctp_assoc_sync_pmtu(sk, asoc); - } + /* drop packet if no dst */ dst = dst_clone(tp->dst); if (!dst) { IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);