openssh bugs - Oct 2011 - [Bug 1942] New: mounting home directory with sshfs -o reconnect requires patch for ssh

https://bugzilla.mindrot.org/show_bug.cgi?id=1942

             Bug #: 1942
           Summary: mounting home directory with sshfs -o reconnect
                    requires patch for ssh
    Classification: Unclassified
           Product: Portable OpenSSH
           Version: 5.8p1
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: ssh
        AssignedTo: unassigned-bugs at mindrot.org
        ReportedBy: e.kuemmerle at fz-juelich.de


Created attachment 2097
  --> https://bugzilla.mindrot.org/attachment.cgi?id=2097
Patch to add the option "-H path_to_per-user_configdir" to ssh

Hi,

we are using sshfs to mount the home directories via pam_mount, the
server is listed in /etc/ssh/ssh_known_hosts.
The problem is, that ssh always wants to read the directory ~/.ssh.

When the initial connection is established, the ssh process creates the
.ssh directory in the empty mount point directory. That doesn't harm
because sshfs can be forced with the nonempty option to mount on that
directory even though it is no longer empty.

But if the ssh connection to the server breaks and sshfs starts a new
ssh process to reconnect, ssh hangs in an uninterruptible sleep
(process state = D) when it tries to read ~/.ssh because the mounted
home directory is not available...

To overcome this deadlock, I patched ssh:
I added an new option "-H path_to_per-user_configdir" that allows to
use path_to_per-user_configdir/.ssh instead of ~/.ssh.
We use now "-H /dev/null". ssh then warns "Could not create
directory
'/dev/null/.ssh'.", but the sshfs mount works properly, including
the
reconnect feature.

IMHO that patch could also help other people, so I suggest to integrate
it in the openssh sources.

Thank you,
  Eberhard

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https://bugzilla.mindrot.org/show_bug.cgi?id=1942

--- Comment #1 from Damien Miller <djm at mindrot.org> 2011-10-14 21:35:27
EST ---
Created attachment 2099
  --> https://bugzilla.mindrot.org/attachment.cgi?id=2099
ssh-mkdir.diff

don't mkdir when -F specified

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |djm at mindrot.org

--- Comment #2 from Damien Miller <djm at mindrot.org> 2011-10-14 21:49:01
EST ---
Think this patch is better, it suppresses the mkdir when the -F option
is passed to ssh so you can use "ssh -F /dev/null"

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--- Comment #3 from e.kuemmerle at fz-juelich.de 2011-10-15 00:33:29 EST ---
Suppressing mkdir ~/.ssh is not enough because ssh still tries to open
some files in that directory!
An alternative patch additionally has to suppress all these open calls!
Then it would work, indeed.

But I think it is more useful to provide the possibility to use a
different directory.

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--- Comment #4 from Damien Miller <djm at mindrot.org> 2011-10-15 10:25:26
EST ---
You can suppress other attempts to read/write from ~/.ssh using
already-existing configuration options (UserKnownHostsFile etc)

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--- Comment #5 from e.kuemmerle at fz-juelich.de 2011-10-17 20:10:27 EST ---
Ok, with the options

-oUserKnownHostsFile=/dev/null -oUserKnownHostsFile2=/dev/null
-oIdentityFile=/dev/null -F /dev/null

your patch would solve the remaining problem.

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |1930
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #6 from Damien Miller <djm at mindrot.org> 2011-12-02 11:12:46
EST ---
The patch has been committed, it will be in OpenSSH-6.0

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