** Also affects: openssh (Ubuntu Trusty)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1334916
Title:
sshd-ConsoleKit integration patch causes abrupt termination of
multichannel sessions
Status in openssh package in Ubuntu:
Fix Released
Status in openssh source package in Trusty:
Triaged
Bug description:
Attached to this report is a small app the reproduces the issue by creating
multiple channels within one sessions. (I fist hit this issue using JSCH
library)
Following information is printed to stdout if sshd is launched with -d flags
(I've modified the sshd code to print PIDs next to debug level):
debug3(7526): monitor_read: checking request 156
debug3(7526): mm_answer_consolekit_register entering
debug1(7526): session_by_tty: session 0 tty /dev/pts/1
debug1(7573): server_input_channel_req: channel 2 request pty-req reply 1
debug1(7573): session_by_channel: session 2 channel 2
debug1(7573): session_input_channel_req: session 2 req pty-req
debug1(7573): Allocating pty.
debug3(7573): mm_request_send entering: type 28
debug3(7573): mm_pty_allocate: waiting for MONITOR_ANS_PTY
debug3(7573): mm_request_receive_expect entering: type 29
debug3(7573): mm_request_receive entering
debug1(7526): Unable to open session: The name org.freedesktop.ConsoleKit was
not provided by any .service files
debug3(7526): mm_request_send entering: type 157
debug3(7526): mm_request_receive entering
debug3(7526): monitor_read: checking request 28
debug3(7526): mm_answer_pty entering
debug2(7526): session_new: allocate (allocated 2 max 10)
debug3(7526): session_unused: session id 2 unused
debug1(7526): session_new: session 2
mm_request_receive_expect: read: rtype 157 != type 29
From the log, it looks as if two processes use the same set of pipes
to communicate to the monitor, one of them is sending
MONITOR_REQ_CONSOLEKIT_REGISTER, while another MONITOR_REQ_PTY, and
because they use same set of pipes, and because both processes use
same pipe FDs, monitor reply is sometimes delivered to the wrong
process.
I can reproduce the failure 90% of time using attached app, which expects
first argument to be host name, second - login and the third - password, that
are defaulted to ubuntu:ubuntu@localhost:
$ ./ssh-multisession
Connecting to localhost...Done!
Authenticating as ubuntu...Done.
Starting channel 0
Starting channel 1
ssh_channel_request_pty()=-1: Socket error: disconnected
Starting channel 2
ssh_channel_open_session()=-1: Writing packet: error on socket (or connection
closed): Operation now in progress
Starting channel 3
The same script works fine if sshd is compiled without consolekit.patch:
./ssh-multisession debian-host debian debian
Connecting to 172.17.162.237...Done!
Authenticating as debian...Done.
Starting channel 0
Starting channel 1
Starting channel 2
Starting channel 3
Starting channel 4
Starting channel 5
Starting channel 6
Starting channel 7
Starting channel 8
Starting channel 9
P.S. To compile a test app one needs to have libssh-dev package
installed on your system.
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