Bug 4925 - VSM Server fails to create new session if sshd log files contains "invalid" \x sequence
Summary: VSM Server fails to create new session if sshd log files contains "invalid" \...
Alias: None
Product: ThinLinc
Classification: Unclassified
Component: VSM Server (show other bugs)
Version: 4.1.1
Hardware: PC Unknown
: P2 Normal
Target Milestone: 4.2.0
Assignee: Peter Åstrand
Keywords: derfian_tester, prosaic
Depends on:
Reported: 2013-12-03 20:33 CET by Peter Åstrand
Modified: 2014-04-02 08:58 CEST (History)
1 user (show)

See Also:
Acceptance Criteria:


Description Peter Åstrand cendio 2013-12-03 20:33:30 CET
During login, VSM Server will parse the sshd log file to determine the client IP. If the log contains a line such as:

Dec  2 08:56:49 scilla sshd[26475]: pam_vas: Authentication <succeeded passwordless> for <Personality> user: <xpeter> account: <xpeter@cendio.se> service: <sshd> reason: <N/A> Access Control Identifier(NT Name):<CENDIO\xpeter>

...the session creation will fail and vsmserver will give this traceback:

2013-12-03 20:27:35 ERROR vsmserver.session: Unhandled exception trying to start new session for astrand on <type 'exceptions.ValueError'> invalid \x escape Traceback (most recent call last):
  File "/opt/thinlinc/modules/thinlinc/vsm/async.py", line 112, in iii11
    obj . handle_read_event ( )
  File "/usr/lib64/python2.6/asyncore.py", line 428, in handle_read_event
  File "/usr/lib64/python2.6/asynchat.py", line 140, in handle_read
  File "/opt/thinlinc/modules/thinlinc/vsm/xmlrpc.py", line 405, in found_terminator
    self . handle_response ( )
  File "/opt/thinlinc/modules/thinlinc/vsm/xmlrpc.py", line 437, in handle_response
    self . handle_returnvalue ( )
  File "/opt/thinlinc/modules/thinlinc/vsm/call_reqsession.py", line 42, in handle_returnvalue
    self . callback ( self . returnvalue )
  File "/opt/thinlinc/modules/thinlinc/vsm/loginhandler_common.py", line 210, in req_session_finished
  File "/opt/thinlinc/modules/thinlinc/vsm/loginhandler_common.py", line 221, in handle_successful_sessionstart
    self.sessinfo['client_ip'] =  self.get_client_ip()
  File "/opt/thinlinc/modules/thinlinc/vsm/loginhandler_common.py", line 365, in get_client_ip
    line = line.decode('string_escape')
ValueError: invalid \x escape

It will not crash, however. 

As the traceback above shows, we are parsing the line with line.decode('string_escape'). This is to support 
non-ASCII usernames; see https://www.cendio.com/bugzilla/show_bug.cgi?id=471#c24. sshd will output escaped string messages. Apparently pam_vas does not.
Comment 2 Peter Åstrand cendio 2013-12-03 21:01:40 CET
One solution would be bug 2796.
Comment 3 Peter Åstrand cendio 2013-12-16 09:51:57 CET
Fixed in 28209; applied patch from comment #1.
Comment 4 Karl Mikaelsson cendio 2014-03-20 19:03:50 CET
Can't seem to provoke vsmserver into a traceback anymore. Tested build 4294 on Solaris (with judicious modifications to syslog.conf and /vsmserver/sshd_log_files).

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