linux.git/net/sctp/input.c, branch v4.20

sctp: use the pmtu from the icmp packet to update transport pathmtu

2018-10-16T05:54:20+00:00

Other than asoc pmtu sync from all transports, sctp_assoc_sync_pmtu
is also processing transport pmtu_pending by icmp packets. But it's
meaningless to use sctp_dst_mtu(t->dst) as new pmtu for a transport.

The right pmtu value should come from the icmp packet, and it would
be saved into transport->mtu_info in this patch and used later when
the pmtu sync happens in sctp_sendmsg_to_asoc or sctp_packet_config.

Besides, without this patch, as pmtu can only be updated correctly
when receiving a icmp packet and no place is holding sock lock, it
will take long time if the sock is busy with sending packets.

Note that it doesn't process transport->mtu_info in .release_cb(),
as there is no enough information for pmtu update, like for which
asoc or transport. It is not worth traversing all asocs to check
pmtu_pending. So unlike tcp, sctp does this in tx path, for which
mtu_info needs to be atomic_t.

Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

rhashtable: split rhashtable.h

2018-06-22T04:43:27+00:00

Due to the use of rhashtables in net namespaces,
rhashtable.h is included in lots of the kernel,
so a small changes can required a large recompilation.
This makes development painful.

This patch splits out rhashtable-types.h which just includes
the major type declarations, and does not include (non-trivial)
inline code.  rhashtable.h is no longer included by anything
in the include/ directory.
Common include files only include rhashtable-types.h so a large
recompilation is only triggered when that changes.

Acked-by: Herbert Xu 
Signed-off-by: NeilBrown 
Signed-off-by: David S. Miller

sctp: remove unnecessary asoc in sctp_has_association

2018-03-27T14:22:11+00:00

After Commit dae399d7fdee ("sctp: hold transport instead of assoc
when lookup assoc in rx path"), it put transport instead of asoc
in sctp_has_association. Variable 'asoc' is not used any more.

So this patch is to remove it, while at it,  it also changes the
return type of sctp_has_association to bool, and does the same
for it's caller sctp_endpoint_is_peeled_off.

Signed-off-by: Xin Long 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller

net: use skb_is_gso_sctp() instead of open-coding

2018-03-09T16:41:47+00:00

As well as the basic conversion, I noticed that a lot of the
SCTP code checks gso_type without first checking skb_is_gso()
so I have added that where appropriate.

Also, document the helper.

Cc: Daniel Borkmann 
Cc: Marcelo Ricardo Leitner 
Signed-off-by: Daniel Axtens 
Signed-off-by: David S. Miller

sctp: do not pr_err for the duplicated node in transport rhlist

2018-02-12T16:39:32+00:00

The pr_err in sctp_hash_transport was supposed to report a sctp bug
for using rhashtable/rhlist.

The err '-EEXIST' introduced in Commit cd2b70875058 ("sctp: check
duplicate node before inserting a new transport") doesn't belong
to that case.

So just return -EEXIST back without pr_err any kmsg.

Fixes: cd2b70875058 ("sctp: check duplicate node before inserting a new transport")
Reported-by: Wei Chen 
Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Acked-by: Neil Horman 
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

sctp: do not retransmit upon FragNeeded if PMTU discovery is disabled

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

Currently, if PMTU discovery is disabled on a given transport, but the
configured value is higher than the actual PMTU, it is likely that we
will get some icmp Frag Needed. The issue is, if PMTU discovery is
disabled, we won't update the information and will issue a
retransmission immediately, which may very well trigger another ICMP,
and another retransmission, leading to a loop.

The fix is to simply not trigger immediate retransmissions if PMTU
discovery is disabled on the given transport.

Changes from v2:
- updated stale comment, noticed by Xin Long

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: fix some type cast warnings introduced by transport rhashtable

2017-10-29T09:03:24+00:00

These warnings were found by running 'make C=2 M=net/sctp/'.

They are introduced by not aware of Endian for the port when
coding transport rhashtable patches.

Fixes: 7fda702f9315 ("sctp: use new rhlist interface on sctp transport rhashtable")
Reported-by: Eric Dumazet 
Signed-off-by: Xin Long 
Signed-off-by: David S. Miller

sctp: add the missing sock_owned_by_user check in sctp_icmp_redirect

2017-10-20T11:53:45+00:00

Now sctp processes icmp redirect packet in sctp_icmp_redirect where
it calls sctp_transport_dst_check in which tp->dst can be released.

The problem is before calling sctp_transport_dst_check, it doesn't
check sock_owned_by_user, which means tp->dst could be freed while
a process is accessing it with owning the socket.

An use-after-free issue could be triggered by this.

This patch is to fix it by checking sock_owned_by_user before calling
sctp_transport_dst_check in sctp_icmp_redirect, so that it would not
release tp->dst if users still hold sock lock.

Besides, the same issue fixed in commit 45caeaa5ac0b ("dccp/tcp: fix
routing redirect race") on sctp also needs this check.

Fixes: 55be7a9c6074 ("ipv4: Add redirect support to all protocol icmp error handlers")
Reported-by: Eric Dumazet 
Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller

sctp: remove the typedef sctp_addip_chunk_t

2017-08-03T16:45:47+00:00

This patch is to remove the typedef sctp_addip_chunk_t, and
replace with struct sctp_addip_chunk in the places where it's
using this typedef.

Signed-off-by: Xin Long 
Signed-off-by: David S. Miller