diff options
author | Xin Long <lucien.xin@gmail.com> | 2023-10-03 13:17:53 -0400 |
---|---|---|
committer | Florian Westphal <fw@strlen.de> | 2023-10-04 14:12:01 +0200 |
commit | 8e56b063c86569e51eed1c5681ce6361fa97fc7a (patch) | |
tree | 8968b4b1f78e0e0bc53b0b59ce579f3250b8eabc /include/linux/netfilter | |
parent | af84f9e447a65b4b9f79e7e5d69e19039b431c56 (diff) |
netfilter: handle the connecting collision properly in nf_conntrack_proto_sctp
In Scenario A and B below, as the delayed INIT_ACK always changes the peer
vtag, SCTP ct with the incorrect vtag may cause packet loss.
Scenario A: INIT_ACK is delayed until the peer receives its own INIT_ACK
192.168.1.2 > 192.168.1.1: [INIT] [init tag: 1328086772]
192.168.1.1 > 192.168.1.2: [INIT] [init tag: 1414468151]
192.168.1.2 > 192.168.1.1: [INIT ACK] [init tag: 1328086772]
192.168.1.1 > 192.168.1.2: [INIT ACK] [init tag: 1650211246] *
192.168.1.2 > 192.168.1.1: [COOKIE ECHO]
192.168.1.1 > 192.168.1.2: [COOKIE ECHO]
192.168.1.2 > 192.168.1.1: [COOKIE ACK]
Scenario B: INIT_ACK is delayed until the peer completes its own handshake
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT] [init tag: 144230885]
192.168.1.2 > 192.168.1.1: sctp (1) [INIT ACK] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [COOKIE ECHO]
192.168.1.2 > 192.168.1.1: sctp (1) [COOKIE ACK]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT ACK] [init tag: 3914796021] *
This patch fixes it as below:
In SCTP_CID_INIT processing:
- clear ct->proto.sctp.init[!dir] if ct->proto.sctp.init[dir] &&
ct->proto.sctp.init[!dir]. (Scenario E)
- set ct->proto.sctp.init[dir].
In SCTP_CID_INIT_ACK processing:
- drop it if !ct->proto.sctp.init[!dir] && ct->proto.sctp.vtag[!dir] &&
ct->proto.sctp.vtag[!dir] != ih->init_tag. (Scenario B, Scenario C)
- drop it if ct->proto.sctp.init[dir] && ct->proto.sctp.init[!dir] &&
ct->proto.sctp.vtag[!dir] != ih->init_tag. (Scenario A)
In SCTP_CID_COOKIE_ACK processing:
- clear ct->proto.sctp.init[dir] and ct->proto.sctp.init[!dir].
(Scenario D)
Also, it's important to allow the ct state to move forward with cookie_echo
and cookie_ack from the opposite dir for the collision scenarios.
There are also other Scenarios where it should allow the packet through,
addressed by the processing above:
Scenario C: new CT is created by INIT_ACK.
Scenario D: start INIT on the existing ESTABLISHED ct.
Scenario E: start INIT after the old collision on the existing ESTABLISHED
ct.
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT] [init tag: 144230885]
(both side are stopped, then start new connection again in hours)
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 242308742]
Fixes: 9fb9cbb1082d ("[NETFILTER]: Add nf_conntrack subsystem.")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'include/linux/netfilter')
-rw-r--r-- | include/linux/netfilter/nf_conntrack_sctp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/netfilter/nf_conntrack_sctp.h b/include/linux/netfilter/nf_conntrack_sctp.h index 625f491b95de..fb31312825ae 100644 --- a/include/linux/netfilter/nf_conntrack_sctp.h +++ b/include/linux/netfilter/nf_conntrack_sctp.h @@ -9,6 +9,7 @@ struct ip_ct_sctp { enum sctp_conntrack state; __be32 vtag[IP_CT_DIR_MAX]; + u8 init[IP_CT_DIR_MAX]; u8 last_dir; u8 flags; }; |