firefox and selinux

[Daniel J Walsh]

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Antonio Olivares wrote:
> Dear all,
> 
> I have set settroubleshoot to allow the following:
> chcon -t unconfined_execmem_exec_t
> '/usr/lib/firefox-3.0b4pre/firefox'
> 
> But it is happening again, I do not understand why I
> need to do it multiple of times.  I see a pattern
> occuring:  I have filed a bug report against
> firefox-b3
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=432198
> 
> I hope that firefox and selinux start to work together
> and not against each other. :)
> 
> Summary:
> 
> SELinux is preventing firefox from making the program
> stack executable.
> 
> Detailed Description:
> 
> The firefox application attempted to make its stack
> executable. This is a
> potential security problem. This should never ever be
> necessary. Stack memory is
> not executable on most OSes these days and this will
> not change. Executable
> stack memory is one of the biggest security problems.
> An execstack error might
> in fact be most likely raised by malicious code.
> Applications are sometimes
> coded incorrectly and request this permission. The
> SELinux Memory Protection
> Tests
> (http://people.redhat.com/drepper/selinux-mem.html)
> web page explains how
> to remove this requirement. If firefox does not work
> and you need it to work,
> you can configure SELinux temporarily to allow this
> access until the application
> is fixed. Please file a bug report
> (http://bugzilla.redhat.com/bugzilla/enter_bug.cgi)
> against this package.
> 
> Allowing Access:
> 
> Sometimes a library is accidentally marked with the
> execstack flag, if you find
> a library with this flag you can clear it with the
> execstack -c LIBRARY_PATH.
> Then retry your application. If the app continues to
> not work, you can turn the
> flag back on with execstack -s LIBRARY_PATH.
> Otherwise, if you trust firefox to
> run correctly, you can change the context of the
> executable to
> unconfined_execmem_exec_t. "chcon -t
> unconfined_execmem_exec_t
> '/usr/lib/firefox-3.0b4pre/firefox'" You must also
> change the default file
> context files on the system in order to preserve them
> even on a full relabel.
> "semanage fcontext -a -t unconfined_execmem_exec_t
> '/usr/lib/firefox-3.0b4pre/firefox'"
> 
> The following command will allow this access:
> 
> chcon -t unconfined_execmem_exec_t
> '/usr/lib/firefox-3.0b4pre/firefox'
> 
> Additional Information:
> 
> Source Context               
> unconfined_u:unconfined_r:unconfined_t:SystemLow-
>                               SystemHigh
> Target Context               
> unconfined_u:unconfined_r:unconfined_t:SystemLow-
>                               SystemHigh
> Target Objects                None [ process ]
> Source                        firefox
> Source Path                  
> /usr/lib/firefox-3.0b3pre/firefox
> Port                          <Unknown>
> Host                          localhost
> Source RPM Packages          
> firefox-3.0-0.beta2.16.nightly20080206.fc9
> Target RPM Packages           
> Policy RPM                   
> selinux-policy-3.2.7-1.fc9
> Selinux Enabled               True
> Policy Type                   targeted
> MLS Enabled                   True
> Enforcing Mode                Enforcing
> Plugin Name                   allow_execstack
> Host Name                     localhost
> Platform                      Linux localhost
> 2.6.24-23.fc9 #1 SMP Wed Feb 6
>                               11:36:31 EST 2008 i686
> athlon
> Alert Count                   11
> First Seen                    Fri 01 Feb 2008 05:08:54
> PM CST
> Last Seen                     Sat 09 Feb 2008 12:35:06
> PM CST
> Local ID                     
> c4806f30-a6dc-43b0-8901-5531075795f7
> Line Numbers                  
> 
> Raw Audit Messages            
> 
> host=localhost type=AVC msg=audit(1202582106.621:28):
> avc:  denied  { execstack } for  pid=9246
> comm="firefox"
> scontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> tcontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> tclass=process
> 
> host=localhost type=SYSCALL
> msg=audit(1202582106.621:28): arch=40000003
> syscall=125 success=no exit=-13 a0=bfa71000 a1=1000
> a2=1000007 a3=fffff000 items=0 ppid=9232 pid=9246
> auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500
> egid=500 sgid=500 fsgid=500 tty=(none) comm="firefox"
> exe="/usr/lib/firefox-3.0b4pre/firefox"
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> key=(null)
> 
> 
> 
> Regards,
> 
> Antonio 
> 
> 
>       ____________________________________________________________________________________
> Never miss a thing.  Make Yahoo your home page. 
> http://www.yahoo.com/r/hs
> 

chcon -t unconfined_execmem_exec_t
'/usr/lib/firefox-3.0b4pre/firefox'

This will only survive until the next relabel.  selinux-policy update
can trigger partial relabels.

# semanage fcontext -a -t unconfined_execmem_exec_t
'/usr/lib/firefox-3.0b4pre/firefox'
# restorecon '/usr/lib/firefox-3.0b4pre/firefox'

Would set the file systems default labeling for firefox and make it
survive a relabel.

As other replies have indicated, this problem is probably a bad plugin.
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