Bug 657786

Summary:

SELinux is preventing /usr/bin/scanimage from making the program stack
executable.

Detailed Description:

The scanimage 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://www.akkadia.org/drepper/selinux-mem.html) web page explains how to
remove this requirement. If scanimage 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.

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 scanimage
to run correctly, you can change the context of the executable to
execmem_exec_t. "chcon -t execmem_exec_t '/usr/bin/scanimage'" 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 execmem_exec_t
'/usr/bin/scanimage'"

Fix Command:

chcon -t execmem_exec_t '/usr/bin/scanimage'

Additional Information:

Source Context                unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1
                              023
Target Context                unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1
                              023
Target Objects                None [ process ]
Source                        scanimage
Source Path                   /usr/bin/scanimage
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           sane-backends-1.0.21-4.fc14
Target RPM Packages           
Policy RPM                    selinux-policy-3.9.7-12.fc14
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Plugin Name                   allow_execstack
Host Name                     (removed)
Platform                      Linux (removed) 2.6.35.6-48.fc14.i686 #1 SMP Fri Oct
                              22 15:34:36 UTC 2010 i686 i686
Alert Count                   1
First Seen                    Sat 27 Nov 2010 04:04:09 PM CST
Last Seen                     Sat 27 Nov 2010 04:04:09 PM CST
Local ID                      e1a199a7-89cf-47a5-93c3-c804ae1d2cf5
Line Numbers                  

Raw Audit Messages            

node=(removed) type=AVC msg=audit(1290895449.349:24374): avc:  denied  { execstack } for  pid=3205 comm="scanimage" scontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 tcontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 tclass=process

node=(removed) type=SYSCALL msg=audit(1290895449.349:24374): arch=40000003 syscall=125 success=no exit=-13 a0=bfead000 a1=1000 a2=1000007 a3=bfea9fd0 items=0 ppid=2214 pid=3205 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 tty=pts0 ses=1 comm="scanimage" exe="/usr/bin/scanimage" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null)



Hash String generated from  allow_execstack,scanimage,unconfined_t,unconfined_t,process,execstack
audit2allow suggests:

#============= unconfined_t ==============
#!!!! This avc can be allowed using the boolean 'allow_execstack'

allow unconfined_t self:process execstack;