Bug 1319934

*** This bug has been marked as a duplicate of bug 1242656 ***

The question I have is 'ssh-transport-c'? And why should it read the /proc/net/unix file? 

I see nothing with the name ssh-transport-c in the file system. The /proc/net/unix file contains a list of all open unix socket connections. 

So how do I figure out what in the world is ssh-transport-c is doing in that file? I don't feel comfortable opening this without knowing what it is and why it's doing that.

Probably a library call?

This has nothing to do with openssh. As mentioned in the "duplicate", it points out to the file in cockpit  src/ws/cockpitsshtransport.c  (truncated thread name?), which is using  libssh  to connect to remote server.

Maybe they will tell you more what is going on under the hood and why they need to read this file?

The libssh code does not open that file. The only unix socket we connect to is the one ssh-agent exports (SSH_AUTH_SOCK).

Agree with Andreas. I looked through libssh for code that might do that. In addition Cockpit does not open that file in its code.

So hence the question to Mirek: How can we figure out which piece of code is accessing that file? I imagine similar issues have come up before when tracking down AVC's right?

You get get more information using extended audit rules.

# auditctl -D
# auditctl -w /etc/shadow -p w

Together with AVC record you will see SYSCALL, PATH, and other which could help.

Dominik, in your opition, would it make sense to add the commands above to the end of our testing teardown logic, and run them if there are unexpected audit messages?

The commands changes rules which auditd uses to filter audit events. You need to run them first and when an event occur it will be consisted of several records.

With the default auditd setting you see can see an audit events with only one AVC record:

type=AVC msg=audit(1461679232.539:924): avc:  denied  { open } for  pid=363 comm="sshd" path="/etc/ssh/ssh_host_ecdsa_key" dev="dm-1" ino=34723961 scontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:admin_home_t:s0 tclass=file permissive=0


When you change the filter using auditctl command, you will see events with multiple records:

type=AVC msg=audit(1461679330.386:932): avc:  denied  { open } for  pid=1389 comm="sshd" path="/etc/ssh/ssh_host_ecdsa_key" dev="dm-1" ino=34723961 scontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:admin_home_t:s0 tclass=file permissive=0
type=SYSCALL msg=audit(1461679330.386:932): arch=c000003e syscall=2 success=no exit=-13 a0=555cf0182aa0 a1=0 a2=7ffdb125ed30 a3=555cef4a1960 items=1 ppid=1 pid=1389 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="sshd" exe="/usr/sbin/sshd" subj=system_u:system_r:sshd_t:s0-s0:c0.c1023 key=(null)
type=CWD msg=audit(1461679330.386:932):  cwd="/"
type=PATH msg=audit(1461679330.386:932): item=0 name="/etc/ssh/ssh_host_ecdsa_key" inode=34723961 dev=fd:01 mode=0100640 ouid=0 ogid=991 rdev=00:00 obj=system_u:object_r:admin_home_t:s0 nametype=NORMAL
type=PROCTITLE msg=audit(1461679330.386:932): proctitle="/usr/sbin/sshd"

I don't think it's a bad thing to increase selinux verbosity in our tests.

On the other hand, we could just run this in a pull request and hammer it with CI until the error occurs again, that way we don't need to increase verbosity on master (and maybe rewrite some rules where we catch expected selinux events).

I don't see a good alternative at this point, unless we want to keep guessing or give up on the error.

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