Bug 5243 - SELinux on RHEL 7 produces AVC denials for access syscalls
Summary: SELinux on RHEL 7 produces AVC denials for access syscalls
Alias: None
Product: ThinLinc
Classification: Unclassified
Component: Server OS (show other bugs)
Version: 4.2.0
Hardware: PC Unknown
: P2 Normal
Target Milestone: 4.3.0
Assignee: Pierre Ossman
Keywords: hean01_tester, prosaic
Depends on:
Blocks: 4939
  Show dependency treegraph
Reported: 2014-09-05 17:34 CEST by Karl Mikaelsson
Modified: 2014-10-06 16:25 CEST (History)
1 user (show)

See Also:
Acceptance Criteria:


Description Karl Mikaelsson cendio 2014-09-05 17:34:35 CEST

Printing a document to nearest (or just running nearest as cupsd_t).

For each os.access(..) made by hiveconf.py (_check_write_access) to check whether a file is writable, two lines like this are printed to the audit log file. syscall=21 on the second line indicates an access call. Everything looks OK from a SELinux file context point of view, so there's nothing odd there.

>    type=AVC msg=audit(1409906549.883:6665): avc:  denied  { write } for  pid=54979 comm="python-thinlinc" name="webaccess.hconf" dev="dm-0" ino=102197015 scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:usr_t:s0 tclass=file
>    type=SYSCALL msg=audit(1409906549.883:6665): arch=c000003e syscall=21 success=no exit=-13 a0=1fa2b60 a1=2 a2=7f61620dff88 a3=642e666e6f632f63 items=0 ppid=18452 pid=54979 auid=4294967295 uid=0 gid=7 euid=0 suid=0 fsuid=0 egid=7 sgid=7 fsgid=7 tty=(none) ses=4294967295 comm="python-thinlinc" exe="/usr/bin/python2.7" subj=system_u:system_r:cupsd_t:s0-s0:c0.c1023 key=(null)

Pierre and I tried to understand why this happens only on RHEL 7 and not on Fedora, but could not figure it out. This needs more investigation.
Comment 2 Pierre Ossman cendio 2014-09-09 17:33:29 CEST
Fixed in r29338 and r29339.

Tester should verify this on both RHEL 7 and RHEL 6, as RHEL 6 has a too old kernel for the audit_access rule and we need to verify that the module still compiles there.
Comment 3 Pierre Ossman cendio 2014-09-10 09:47:23 CEST
The autotest machines are having problems with this change. Need to have another look.
Comment 4 Pierre Ossman cendio 2014-09-11 11:02:37 CEST
Turns out that we do not need the audit_access rule. Tagging the config files as etc_t instead of usr_t is enough to get rid of the noise.

Fixed in r29343.
Comment 5 Henrik Andersson cendio 2014-09-24 13:35:17 CEST
Verified that context is etc_t and that the AVC is not showing up on both RHEL6 and RHEL7. Using ThinLinc server build 4499.

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