Bug 811672

For your ease, the RHS url:

http://docs.redhat.com/docs/en-US/Red_Hat_Storage/2/html/User_Guide/ch09s02s05s02.html

Anything in the audit log?

I suspect this is caused by SELinux. Here's the audit log.

-----
May  9 09:01:30 rhs20b2-02 kernel: type=1400 audit(1336554090.683:5): avc:  denied  { read } for  pid=2130 comm="umount" name="mnt48dS2M" dev=vda2 ino=29940 scontext=unconfined_u:system_r:mount_t:s0 tcontext=unconfined_u:object_r:var_t:s0 tclass=lnk_file
-----

And because of this, geo-replication with an unprivileged user, such as below, fails.

# gluster vol geo-replication vol01 geoaccount@rhs20b2-02::vol01_slave


A workaround is to "setenforce 0", but the final resolution should be an appropriate context labeling....

Workaround available. Removing 3.3.0 milestone from this bug.

Etsuji: can you help us in dechipering the audit log entry? What is weird that the mount in question is created by glusterd (that is uid=0) and is to be taken down by glusterd too.

So it's a case of:
- root cannot do an umount
- the one who asked the system for some resource is not authorized to ask the system to release the resource

-- both seems contraintuitive from a naive POV. Which part of the context does imply this?

Ok... I did some investigation, and my hypothesis is:

- "umount" is forked from "glusterd", which is started by the upstart sequence.
- "mount" is forked from "gluterfs", which is forked from "glusterd".

Because of the difference of fork chain, "umount" and "mount" have differenct seculity contexts, and only "umount" is denied by SElinux.

Following is the result of my investigation which lead to the above hypothesis. 

====
1. After setting SELinux to Permissive mode and starting psacct on slave, I started georep from master.

2. According to the audit log on slave, "umount" has pid=1675, and its security context is "scontext=system_u:system_r:mount_t:s0".

Jun  9 10:37:56 slave01 kernel: type=1400 audit(1339238276.342:5): avc:  denied  { read } for  pid=1675 comm="umount" name="mnt3Tj3nM" dev=vda2 ino=30095 scontext=system_u:system_r:mount_t:s0 tcontext=system_u:object_r:var_t:s0 tclass=lnk_file

3. According to the psacct log shown by "lastcomm --pid" on slave, the "umount" (pid=1675) is forked from pid=1217.

---------------
gluster               X georep01 __         0.00 secs Sat Jun  9 10:37     1671     1646
umount            S     root     __         0.00 secs Sat Jun  9 10:37     1675     1217
python                  georep01 __         0.03 secs Sat Jun  9 10:37     1673     1671
gluster               X georep01 __         0.00 secs Sat Jun  9 10:37     1656     1646
glusterfs         S     root     __         0.01 secs Sat Jun  9 10:37     1660     1217
mount             S     root     __         0.00 secs Sat Jun  9 10:37     1661     1660
python                  georep01 __         0.02 secs Sat Jun  9 10:37     1658     1656
---------------

And, pid=1271 is a "glusterd" launched by the upstart sequence, which has the security context "system_u:system_r:initrc_t:s0" as below.

# ps -efZ | grep 121[7]
system_u:system_r:initrc_t:s0   root      1217     1  0 10:30 ?        00:00:00 /usr/sbin/glusterd --pid-file=/var/run/glusterd.pid

4. On the otherhand, according to the same psacct log, "mount" (not denied) is forked from "glusterfs", not directly from "glusterd".
=====

To confirm the hypothesis, I stopped "glusterd" and started it again directly from the command line. Then "glusterd" has a different security context as below.

# ps -efZ | grep 1730
unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 root 1730 1  1 10:45 ? 00:00:00 /usr/sbin/glusterd --pid-file=/var/run/glusterd.pid

In this case, georep succeeded without any SElinux prevention.

This bug does not block 820843, removing the dependency.