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authorDirkjan Bussink <d.bussink@gmail.com>2020-12-10 13:20:34 +0000
committerAndreas Schneider <asn@cryptomilk.org>2020-12-11 13:29:46 +0100
commitf6a2f6190c2aa047d901547720ae6d1729e1e2c0 (patch)
tree760e9a91c992ee55f49adb79dbecce07ccc2f559 /src/packet.c
parent3c33c3945523a9d07c541c77017ac2639305e13a (diff)
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Ignore request success and failure message if they are not expected
In https://gitlab.com/libssh/libssh-mirror/-/merge_requests/145#note_463232084 behavior in libssh was identified where it diverges from how for example OpenSSH behaves. In OpenSSH if a request success of failure message is received, apart from it being treated as a keepalive message, it is ignored otherwise. Libssh does handle the unexpected message and triggers an error condition internally. This means that with the Dropbear behavior where it replies to a hostkeys-00@openssh.com message even with a want_reply = 0 (arguably a bug), libssh enters an error state. This change makes the libssh behavior match OpenSSH to ignore these messages. The spec is a bit unclear on whether Dropbear is buggy here or not, but let's be liberal with the input accepted here in libssh. Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com> Reviewed-by: Jakub Jelen <jjelen@redhat.com> Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Diffstat (limited to 'src/packet.c')
-rw-r--r--src/packet.c34
1 files changed, 16 insertions, 18 deletions
diff --git a/src/packet.c b/src/packet.c
index f14731c9..2d376620 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -688,10 +688,12 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
/*
* States required:
* - session_state == SSH_SESSION_STATE_AUTHENTICATED
- * - session->global_req_state == SSH_CHANNEL_REQ_STATE_PENDING
*
* Transitions:
- * - session->global_req_state == SSH_CHANNEL_REQ_STATE_ACCEPTED
+ * - From channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
+ * - To channel->request_state = SSH_CHANNEL_REQ_STATE_ACCEPTED
+ *
+ * If not in a pending state, message is ignored in the callback handler.
* */
if (session->session_state != SSH_SESSION_STATE_AUTHENTICATED) {
@@ -699,21 +701,18 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
break;
}
- if (session->global_req_state != SSH_CHANNEL_REQ_STATE_PENDING) {
- rc = SSH_PACKET_DENIED;
- break;
- }
-
rc = SSH_PACKET_ALLOWED;
break;
case SSH2_MSG_REQUEST_FAILURE: // 82
/*
* States required:
* - session_state == SSH_SESSION_STATE_AUTHENTICATED
- * - session->global_req_state == SSH_CHANNEL_REQ_STATE_PENDING
*
* Transitions:
- * - session->global_req_state == SSH_CHANNEL_REQ_STATE_DENIED
+ * - From channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
+ * - To channel->request_state = SSH_CHANNEL_REQ_STATE_ACCEPTED
+ *
+ * If not in a pending state, message is ignored in the callback handler.
* */
if (session->session_state != SSH_SESSION_STATE_AUTHENTICATED) {
@@ -721,11 +720,6 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
break;
}
- if (session->global_req_state != SSH_CHANNEL_REQ_STATE_PENDING) {
- rc = SSH_PACKET_DENIED;
- break;
- }
-
rc = SSH_PACKET_ALLOWED;
break;
case SSH2_MSG_CHANNEL_OPEN: // 90
@@ -878,10 +872,12 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
/*
* States required:
* - session_state == SSH_SESSION_STATE_AUTHENTICATED
- * - channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
*
* Transitions:
- * - channel->request_state = SSH_CHANNEL_REQ_STATE_ACCEPTED
+ * - From channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
+ * - To channel->request_state = SSH_CHANNEL_REQ_STATE_ACCEPTED
+ *
+ * If not in a pending state, message is ignored in the callback handler.
* */
if (session->session_state != SSH_SESSION_STATE_AUTHENTICATED) {
@@ -895,10 +891,12 @@ static enum ssh_packet_filter_result_e ssh_packet_incoming_filter(ssh_session se
/*
* States required:
* - session_state == SSH_SESSION_STATE_AUTHENTICATED
- * - channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
*
* Transitions:
- * - channel->request_state = SSH_CHANNEL_REQ_STATE_DENIED
+ * - From channel->request_state == SSH_CHANNEL_REQ_STATE_PENDING
+ * - To channel->request_state = SSH_CHANNEL_REQ_STATE_ACCEPTED
+ *
+ * If not in a pending state, message is ignored in the callback handler.
* */
if (session->session_state != SSH_SESSION_STATE_AUTHENTICATED) {