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packet: do not enqueue outgoing packets after sending SSH2_MSG_NEWKEYS

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When we decide we need to rekey, we enqueue any further packets until we've sent
our SSH2_MSG_NEWKEYS message, after which we dequeue these packets and send them
to the other side. This enqueueing is done based on ssh_packet_in_rekey checking
the session flags and whether DH handshake state is marked as finished.

However, the handshake state is not reset to DH_STATE_FINISHED until the other
side has sent us their new keys. This leaves a gap between sending our new keys
and receiving the other side's new keys where we would still decide to enqueue a
packet.

These enqueued packets will not be dequeued as we've already sent our new keys.
Once we've received the other side's new keys, we'll go back to a finished
handshake and we will send out our caller's new data, skipping however much data
we've enqueued.

Fix this by changing ssh_packet_in_rekey to return false once we've sent our new
keys.

Signed-off-by: Carlos Martín Nieto <carlosmn@github.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
This commit is contained in:
Carlos Martín Nieto
2022-09-07 15:26:01 +02:00
committed by Jakub Jelen
parent 20d9642c4c
commit 346e6db318
1 changed files with 4 additions and 2 deletions
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6
src/packet.c
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@@ -1755,10 +1755,12 @@ static bool
ssh_packet_in_rekey(ssh_session session) ssh_packet_in_rekey(ssh_session session)
{ {
/* We know we are rekeying if we are authenticated and the DH /* We know we are rekeying if we are authenticated and the DH
* status is not finished * status is not finished, but we only queue packets until we've
* sent our NEWKEYS.
*/ */
return (session->flags & SSH_SESSION_FLAG_AUTHENTICATED) && return (session->flags & SSH_SESSION_FLAG_AUTHENTICATED) &&
(session->dh_handshake_state != DH_STATE_FINISHED); (session->dh_handshake_state != DH_STATE_FINISHED) &&
(session->dh_handshake_state != DH_STATE_NEWKEYS_SENT);
} }
int ssh_packet_send(ssh_session session) int ssh_packet_send(ssh_session session)