[PATCH 5.10 67/77] sctp: fix the processing for COOKIE_ECHO chunk

Greg Kroah-Hartman
2021-11-01T09:39:52Z

From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit a64b341b8695e1c744dd972b39868371b4f68f83 ]

1. In closed state: in sctp_sf_do_5_1D_ce():

When asoc is NULL, making packet for abort will use chunk's vtag
in sctp_ootb_pkt_new(). But when asoc exists, vtag from the chunk
should be verified before using peer.i.init_tag to make packet
for abort in sctp_ootb_pkt_new(), and just discard it if vtag is
not correct.

2. In the other states: in sctp_sf_do_5_2_4_dupcook():

asoc always exists, but duplicate cookie_echo's vtag will be
handled by sctp_tietags_compare() and then take actions, so before
that we only verify the vtag for the abort sent for invalid chunk
length.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sctp/sm_statefuns.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 5063f9884367..0cfbf6046bf8 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -697,6 +697,9 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
struct sock *sk;
int error = 0;

+ if (asoc && !sctp_vtag_verify(chunk, asoc))
+ return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
+
/* If the packet is an OOTB packet which is temporarily on the
* control endpoint, respond with an ABORT.
*/
@@ -711,7 +714,8 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
* in sctp_unpack_cookie().
*/
if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
- return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
+ return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
+ commands);

/* If the endpoint is not listening or if the number of associations
* on the TCP-style socket exceed the max backlog, respond with an
@@ -2141,9 +2145,11 @@ enum sctp_disposition sctp_sf_do_5_2_4_dupcook(
* enough for the chunk header. Cookie length verification is
* done later.
*/
- if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
- return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
- commands);
+ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) {
+ if (!sctp_vtag_verify(chunk, asoc))
+ asoc = NULL;
+ return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands);
+ }

/* "Decode" the chunk. We have no optional parameters so we
* are in good shape.
--
2.33.0