Bug 131187

Summary: fstab-sync trashes /etc/fstab's SELinux context
Product: [Fedora] Fedora Reporter: W. Michael Petullo <redhat>
Component: halAssignee: David Zeuthen <davidz>
Status: CLOSED RAWHIDE QA Contact:
Severity: high Docs Contact:
Priority: medium    
Version: rawhideCC: mclasen, russell
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2004-09-01 06:00:27 EDT Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Bug Depends On:    
Bug Blocks: 123268, 130887    
Attachments:
Description Flags
Output from "hald --daemon=no --verbose=yes" none

Description W. Michael Petullo 2004-08-28 12:58:04 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux ppc; en-US; rv:1.7.2)
Gecko/20040809 Epiphany/1.3.5

Description of problem:
Running fstab-sync causes the SELinux context of /etc/fstab to go from
system_u:object_r:etc_t to root:object_r:tmp_t.  This causes system
boots to fail when SELinux is enforcing Fedora's strict policy.  The
boot process fails when it tries to run fsck.

Version-Release number of selected component (if applicable):
hal-0.2.97.cvs20040827-2

How reproducible:
Always

Steps to Reproduce:
[root@imp default]# ls -lZ /etc/fstab
-rw-r--r-- root root system_u:object_r:etc_t /etc/fstab
[root@imp default]# fstab-sync -c
[root@imp default]# ls -lZ /etc/fstab
-rw-r--r-- root root root:object_r:tmp_t /etc/fstab
[root@imp default]# restorecon /etc/fstab
[root@imp default]# ls -lZ /etc/fstab
-rw-r--r-- root root system_u:object_r:etc_t /etc/fstab
    

Expected Results:  Running fstab-sync should not change the SELinux
context of /etc/fstab.

Additional info:
Comment 1 David Zeuthen 2004-08-28 13:12:33 EDT
Thanks for the report. I'll look into this.
Comment 2 Tom London 2004-08-28 17:11:22 EDT
Glad I checked before I filed.... 

I'm seeing this too with hal-0.2.97.cvs20040827-3.
Comment 3 David Zeuthen 2004-08-29 18:22:04 EDT
Alright, I've added support for this in fstab-sync. I don't have a
selinux system available presently, so please try this fstab-sync
binary here

 http://freedesktop.org/~david/selinux/

it's for i386; let me know if you use another architecture and I'll
build some RPMS insteads. Should this not work, please include the
output of 'hald --daemon=no verbose=yes' running as root (remember to
stop the haldaemon service).

Thanks,
David
Comment 4 David Zeuthen 2004-08-29 18:50:02 EDT
I just saw that you are using PPC (at least your browser suggests
that), so I've just uploaded a SRPM to the location given above (built
at my local box). If it looks good I'll put this into Rawhide, so
please let me know how it works out.
Comment 5 W. Michael Petullo 2004-08-29 21:28:46 EDT
Created attachment 103224 [details]
Output from "hald --daemon=no --verbose=yes"

I just tried hal-0.2.97.cvs20040830-1 and the problem remains.	I verified that
fstab-sync is linked against libselinux.

This has also been talked about on the fedora-selinux mailing list:

http://www.redhat.com/archives/fedora-selinux-list/2004-August/msg00204.html
Comment 6 David Zeuthen 2004-08-30 04:47:09 EDT
OK, here we go again, please try 

 http://freedesktop.org/~david/selinux/hal-0.2.97.cvs20040830-2.src.rpm

Now we don't create the temporary file in /tmp but rather in /etc.

Please give a 'ls -lZ /etc/fstab' and hald dump if this still fails.
Much thanks.
Comment 7 W. Michael Petullo 2004-08-30 20:43:44 EDT
Here are the results with hal-0.2.97.cvs20040830-2:

[root@imp /]# ls -lZ /etc/fstab
-rw-r--r-- root root system_u:object_r:etc_t /etc/fstab
[root@imp /]# fstab-sync -c /etc/fstab
[root@imp /]# ls -lZ /etc/fstab
-rw-r--r-- root root root:object_r:etc_t /etc/fstab
[root@imp /]# restorecon /etc/fstab
[root@imp /]# ls -lZ /etc/fstab
-rw-r--r-- root root system_u:object_r:etc_t /etc/fstab

This is closer but now we switch from system_u:object_r:etc_t to
root:object_r:etc_t.
Comment 8 David Zeuthen 2004-08-30 21:23:13 EDT
Alright, I think I know what is wrong, please try with this one

 http://people.redhat.com/davidz/hal-0.2.97.cvs20040831-1.src.rpm

if it doesn't work please post the output of 'fstab-sync -c -v' (the
-v is important). Much thanks.
Comment 9 David Zeuthen 2004-08-30 21:29:24 EDT
Btw, I implemented this using code from restorecon to save a fork+exec
and possible error paths; does this mean that fstab-sync will require
some extra privs to relabel files? Is this the recommended way to do
this? 

(FWIW, I have to rename a tmp file in /etc to /etc/fstab to achieve
atomicity in the update; but now that I need to do the restorecon
thing this no longer appears atomic on selinux; we may fail between
rename(2) and restorecon, right? Hmm).
Comment 10 W. Michael Petullo 2004-08-30 22:38:43 EDT
hal-0.2.97.cvs20040831-1 seems to fix things.  

I did get the following SELinux-related log (SELinux is not currently
enforcing my policy -- only checking):

Aug 30 21:36:02 imp kernel: audit(1093919762.305:0): avc:  denied  {
read } for  pid=15888 exe=/usr/sbin/fstab-sync path=pipe:[20827]
dev=pipefs ino=20827 scontext=root:system_r:updfstab_t
tcontext=user_u:user_r:user_su_t tclass=fifo_file
Aug 30 21:36:02 imp fstab-sync[15888]: removed all generated mount points

...but it seems dbus, udev and crew in general have a lot of issues
with the current strict policy anyway.

It seems that there is a lot of copy and pasting of code from
restorecon.c.  It's unfortunate if there is no higher level function
to do something that seems this fundamental.

I would also be interested in seeing comment on the atomic issue
raised in comment #9.
Comment 11 David Zeuthen 2004-09-01 06:00:27 EDT
I've built hal-0.2.97.cvs20040901-1 into Rawhide with this fix - I'll
keep the atomic issue with in mind. Thanks.
Comment 12 David Zeuthen 2004-09-01 06:05:51 EDT
*** Bug 131413 has been marked as a duplicate of this bug. ***