lwn.git/net/sctp/transport.c, branch docs-5.3

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 104

2019-05-24T15:39:00+00:00

Based on 1 normalized pattern(s): this sctp implementation is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 or at your option any later version this sctp implementation is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with gnu cc see the file copying if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 42 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Kate Stewart Reviewed-by: Richard Fontana Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190523091649.683323110@linutronix.de Signed-off-by: Greg Kroah-Hartman

sctp: don't compare hb_timer expire date before starting it

2019-02-22T19:11:54+00:00

hb_timer might not start at all for a particular transport because its start is conditional. In a result a node is not sending heartbeats. Function sctp_transport_reset_hb_timer has two roles: - initial start of hb_timer for a given transport, - update expire date of hb_timer for a given transport. The function is optimized to update timer's expire only if it is before a new calculated one but this comparison is invalid for a timer which has not yet started. Such a timer has expire == 0 and if a new expire value is bigger than (MAX_JIFFIES / 2 + 2) then "time_before" macro will fail and timer will not start resulting in no heartbeat packets send by the node. This was found when association was initialized within first 5 mins after system boot due to jiffies init value which is near to MAX_JIFFIES. Test kernel version: 4.9.154 (ARCH=arm) hb_timer.expire = 0; //initialized, not started timer new_expire = MAX_JIFFIES / 2 + 2; //or more time_before(hb_timer.expire, new_expire) == false Fixes: ba6f5e33bdbb ("sctp: avoid refreshing heartbeat timer too often") Reported-by: Marcin Stojek Tested-by: Marcin Stojek Signed-off-by: Maciej Kwiecien Reviewed-by: Alexander Sverdlin Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: update dst pmtu with the correct daddr

2018-09-20T18:29:30+00:00

When processing pmtu update from an icmp packet, it calls .update_pmtu with sk instead of skb in sctp_transport_update_pmtu. However for sctp, the daddr in the transport might be different from inet_sock->inet_daddr or sk->sk_v6_daddr, which is used to update or create the route cache. The incorrect daddr will cause a different route cache created for the path. So before calling .update_pmtu, inet_sock->inet_daddr/sk->sk_v6_daddr should be updated with the daddr in the transport, and update it back after it's done. The issue has existed since route exceptions introduction. Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.") Reported-by: ian.periam@dialogic.com Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: fix the issue that pathmtu may be set lower than MINSEGMENT

2018-07-04T12:36:34+00:00

After commit b6c5734db070 ("sctp: fix the handling of ICMP Frag Needed for too small MTUs"), sctp_transport_update_pmtu would refetch pathmtu from the dst and set it to transport's pathmtu without any check. The new pathmtu may be lower than MINSEGMENT if the dst is obsolete and updated by .get_dst() in sctp_transport_update_pmtu. In this case, it could have a smaller MTU as well, and thus we should validate it against MINSEGMENT instead. Syzbot reported a warning in sctp_mtu_payload caused by this. This patch refetches the pathmtu by calling sctp_dst_mtu where it does the check against MINSEGMENT. v1->v2: - refetch the pathmtu by calling sctp_dst_mtu instead as Marcelo's suggestion. Fixes: b6c5734db070 ("sctp: fix the handling of ICMP Frag Needed for too small MTUs") Reported-by: syzbot+f0d9d7cba052f9344b03@syzkaller.appspotmail.com Suggested-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller

sctp: not allow transport timeout value less than HZ/5 for hb_timer

2018-06-05T14:22:45+00:00

syzbot reported a rcu_sched self-detected stall on CPU which is caused by too small value set on rto_min with SCTP_RTOINFO sockopt. With this value, hb_timer will get stuck there, as in its timer handler it starts this timer again with this value, then goes to the timer handler again. This problem is there since very beginning, and thanks to Eric for the reproducer shared from a syzbot mail. This patch fixes it by not allowing sctp_transport_timeout to return a smaller value than HZ/5 for hb_timer, which is based on TCP's min rto. Note that it doesn't fix this issue by limiting rto_min, as some users are still using small rto and no proper value was found for it yet. Reported-by: syzbot+3dcd59a1f907245f891f@syzkaller.appspotmail.com Suggested-by: Marcelo Ricardo Leitner Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller

sctp: re-use sctp_transport_pmtu in sctp_transport_route

2018-04-27T18:35:23+00:00

sctp_transport_route currently is very similar to sctp_transport_pmtu plus a few other bits. This patch reuses sctp_transport_pmtu in sctp_transport_route and removes the duplicated code. Also, as all calls to sctp_transport_route were forcing the dst release before calling it, let's just include such release too. Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: introduce sctp_dst_mtu

2018-04-27T18:35:23+00:00

Which makes sure that the MTU respects the minimum value of SCTP_DEFAULT_MINSEGMENT and that it is correctly aligned. Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: move transport pathmtu calc away of sctp_assoc_add_peer

2018-04-27T18:35:22+00:00

There was only one case that sctp_assoc_add_peer couldn't handle, which is when SPP_PMTUD_DISABLE is set and pathmtu not initialized. So add this situation to sctp_transport_route and reuse what was already in there. Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

sctp: fix the handling of ICMP Frag Needed for too small MTUs

2018-01-08T19:19:13+00:00

syzbot reported a hang involving SCTP, on which it kept flooding dmesg with the message: [ 246.742374] sctp: sctp_transport_update_pmtu: Reported pmtu 508 too low, using default minimum of 512 That happened because whenever SCTP hits an ICMP Frag Needed, it tries to adjust to the new MTU and triggers an immediate retransmission. But it didn't consider the fact that MTUs smaller than the SCTP minimum MTU allowed (512) would not cause the PMTU to change, and issued the retransmission anyway (thus leading to another ICMP Frag Needed, and so on). As IPv4 (ip_rt_min_pmtu=556) and IPv6 (IPV6_MIN_MTU=1280) minimum MTU are higher than that, sctp_transport_update_pmtu() is changed to re-fetch the PMTU that got set after our request, and with that, detect if there was an actual change or not. The fix, thus, skips the immediate retransmission if the received ICMP resulted in no change, in the hope that SCTP will select another path. Note: The value being used for the minimum MTU (512, SCTP_DEFAULT_MINSEGMENT) is not right and instead it should be (576, SCTP_MIN_PMTU), but such change belongs to another patch. Changes from v1: - do not disable PMTU discovery, in the light of commit 06ad391919b2 ("[SCTP] Don't disable PMTU discovery when mtu is small") and as suggested by Xin Long. - changed the way to break the rtx loop by detecting if the icmp resulted in a change or not Changes from v2: none See-also: https://lkml.org/lkml/2017/12/22/811 Reported-by: syzbot Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller

net: sctp: Convert timers to use timer_setup()

2017-10-25T03:02:09+00:00

In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: Vlad Yasevich Cc: Neil Horman Cc: "David S. Miller" Cc: linux-sctp@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: David S. Miller