Re: Checking for disconnects within ssh_auth_response_termination()?

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Thursday, 19 October 2017 22:48:32 CET Karl Scott wrote:
> Hey folks,
> 
> I've been working with libssh for some time now, and saw that the function
> that ends up being looped over from within
> ssh_handle_packets_termination(), in src/session.c, during an
> authentication attempt is often ssh_auth_response_termination().

Aris, is the patch below OK for you?

> I noticed that in this small function:
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> *static int ssh_auth_response_termination(void *user){  ssh_session
> session=(ssh_session)user;  switch(session->auth_state){    case
> SSH_AUTH_STATE_NONE:    case SSH_AUTH_STATE_KBDINT_SENT:    case
> SSH_AUTH_STATE_GSSAPI_REQUEST_SENT:    case SSH_AUTH_STATE_GSSAPI_TOKEN:
> case SSH_AUTH_STATE_GSSAPI_MIC_SENT:      return 0;    default:      return
> 1;  }}*
> 
> We do not check for session disconnects, so if the session disconnects
> while we are looping over this, we won't stop looping until we simply time
> out.
> 
> Is this intended, as maybe the session will reconnect somehow while we are
> looping in here? If it is not the case that the session might reconnect,
> may I propose this patch that I am currently using internally:
> 
> --- src/auth.c    2016-02-22 23:16:40.000000000 -0800
> +++ src/auth.modified.c    2017-10-19 12:35:06.774460055 -0700
> @@ -79,6 +79,10 @@
> 
>  static int ssh_auth_response_termination(void *user){
>    ssh_session session=(ssh_session)user;
> +  if (ssh_is_connected(session) == 0) {
> +      session->auth_state = SSH_AUTH_STATE_FAILED;
> +      return 1; /* don't wait to time out if the session disconnects */
> +  }
>    switch(session->auth_state){
>      case SSH_AUTH_STATE_NONE:
>      case SSH_AUTH_STATE_KBDINT_SENT:
> 
> I am happy to submit this patch formally, but I wanted to bounce it off of
> the community first. I may be overlooking something here. See any problems?
> 
> Thank you,
> 
> Karl


-- 
Andreas Schneider                   GPG-ID: CC014E3D
www.cryptomilk.org                asn@xxxxxxxxxxxxxx