Thanks Imre! I've updated the 'regression-potential' and subscribed ubuntu-sru and ubuntu-sponsors.
** Tags added: patch ** Description changed: When sshd gets a signal 1 for reload, it forks a new process and ditches the old. This causes upstart to believe that ssh has crashed, and loses track of it. A second reload (or any other initctl operation on ssh) will thus say: reload: Unknown instance: There would be 2 ways to fix this: 1. Don't have ssh fork on relod, but keep the same pid 2. Use a different mechanism in upstart to keep track of ssh. Maybe a pid file? Just tracking children of the exited ssh won't work, or it might accidentally track a particular session rather than the master, if somebody just happens to log in close to reload time. openssh-server 1:5.3p1-3ubuntu4 upstart 0.6.5-7 ==== Info for Maverick, Lucid SRU ==== IMPACT: if sshd gets a HUP signal, it forks a new process and upstart thinks the process died and loses track of it, so the user/admin uses the ability to stop/start/reload the daemon through upstart. The problem is fixed in Natty 5.6p1-2ubuntu3. See attached patches for Maverick and Lucid. TEST CASE: - install openssh-server - send a HUP signal to sshd - the daemon is restarted, but upstart thinks that it crashed (/var/log/daemon.log): Dec 28 20:59:57 utest-lls32 init: ssh main process ended, respawning Dec 28 20:59:57 utest-lls32 init: ssh main process (1451) terminated with status 255 Dec 28 20:59:57 utest-lls32 init: ssh main process ended, respawning Dec 28 20:59:57 utest-lls32 init: ssh main process (1455) terminated with status 255 Dec 28 20:59:57 utest-lls32 init: ssh respawning too fast, stopped - after this, upstart won't know about sshd, despite the daemon running just fine: r...@utest-lls32:~# reload ssh - reload: Unknown instance: + reload: Unknown instance: With the fix applied, the correct behavior is: - send a HUP signal to sshd - ps ax |grep sshd - kill -HUP sshd + ps ax |grep sshd + kill -HUP sshd - the daemon reloads (/var/log/auth.log): Dec 28 21:37:01 utest-lls32 sshd[742]: Received SIGHUP; restarting. Dec 28 21:37:01 utest-lls32 sshd[742]: Server listening on 0.0.0.0 port 22. Dec 28 21:37:01 utest-lls32 sshd[742]: Server listening on :: port 22. - reloading with upstart gives the same result, and NOT an error message. - REGRESSION POTENTIAL: TODO + REGRESSION POTENTIAL: + + There is a small race condition in sshd between when it forks, and when + it listens for incoming connections. The length of the race is + lengthened by a very tiny amount by considering sshd started as soon as + it has been executed, rather than when it forks. This will only affect + jobs that use 'start on started ssh' and immediately connect to it. This + is unlikely to cause problems in any real world scenario, given that + most of these programs would also have to fork, exec, and open a socket, + which is more work than what sshd will be doing in that time. -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to openssh in ubuntu. https://bugs.launchpad.net/bugs/687535 Title: upstart loses track of ssh daemon after reload ssh -- Ubuntu-server-bugs mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
