AVC messages

Forrest Taylor ftaylor at redhat.com
Wed May 30 13:25:33 UTC 2007


On Wed, 2007-05-30 at 11:36 +0100, Tony Molloy wrote:
> Hi,
> 
> I've got httpd running on CentOS-5 with all the latest update.
> 
> I'm getting the following AVC denied messages from SElinux. Now I
> don't want to disable SElinux for the httpd daemon as this server will
> be available on the internet.
> 
> 1.
> 
> [root at alpha ~]# sealert -l 8c3ce37b-fbf3-459b-87d9-e4c4727276eb
> 
> Summary
> 
> SELinux is preventing /usr/sbin/httpd (httpd_t) "sys_nice" access to
> 
> <Unknown> (httpd_t).
> 
> Allowing Access
> 
> Sometimes labeling problems can cause SELinux denials. You could try
> 
> to restore the default system file context for <Unknown>,
> 
> restorecon -v <Unknown>. 
> 
> Raw Audit Messages 
> 
> avc: denied { sys_nice } for comm="httpd" egid=0 euid=0
> exe="/usr/sbin/httpd"
> 
> exit=0 fsgid=0 fsuid=0 gid=0 items=0 pid=2241
> 
> scontext=system_u:system_r:httpd_t:s0 sgid=0
> subj=system_u:system_r:httpd_t:s0
> 
> suid=0 tclass=capability tcontext=system_u:system_r:httpd_t:s0 tty=
> (none) uid=0

Are you trying to set the nice level here?


> 2.
> 
> [root at alpha ~]# sealert -l 87d837ba-bae0-4cbc-8a93-344e6dc67295
> 
> Summary
> 
> SELinux is preventing the /bin/netstat from using potentially
> 
> mislabeled files net (proc_net_t).
> 
> Detailed Description
> 
> SELinux has denied the /bin/netstat access to potentially mislabeled
> 
> files net. This means that SELinux will not allow http to use these
> 
> files. Many third party apps install html files in directories that
> 
> SELinux policy can not predict. These directories have to be labeled 
> 
> with a file context which httpd can accesss.
> 
> Allowing Access
> 
> If you want to change the file context of net so that the httpd daemon
> 
> can access it, you need to execute it using
> 
> chcon -t httpd_sys_content_t.net.
> 
> You can look at the httpd_selinux man page for additional information.
> 
> Raw Audit Messages 
> 
> avc: denied { read } for comm="netstat" dev=proc egid=0 euid=0
> 
> exe="/bin/netstat" exit=-13 fsgid=0 fsuid=0 gid=0 items=0 name="net"
> pid=2255 scontext=system_u:system_r:httpd_t:s0 sgid=0
> subj=system_u:system_r:httpd_t:s0
> 
> suid=0 tclass=dir tcontext=system_u:object_r:proc_net_t:s0 tty=(none)
> uid=0

Is netstat mislabeled, or is the web server trying to get to /proc/net?
What does `ls -Z /bin/netstat` show?

> 3.
> 
> [root at alpha ~]# sealert -l b6d8bb36-32f7-4b10-9c09-331c6298fede
> 
> Summary
> 
> SELinux is preventing /bin/netstat (httpd_t) "create" access to
> 
> <Unknown> (httpd_t).
> 
> Raw Audit Messages 
> 
> avc: denied { create } for comm="netstat" egid=0 euid=0
> exe="/bin/netstat"
> 
> exit=-13 fsgid=0 fsuid=0 gid=0 items=0 pid=2255
> 
> scontext=system_u:system_r:httpd_t:s0 sgid=0
> subj=system_u:system_r:httpd_t:s0
> 
> suid=0 tclass=socket tcontext=system_u:system_r:httpd_t:s0 tty=(none)
> uid=0
> 
> The test server seems to be working OK, so are these messages I can
> safely ignore. Alternatively how can I get rid of them without
> disaling SElinux for the httpd server.

I am curious about these netstat errors.  Are you running something on
your web server that is running netstat?  It is fairly easy to setup
some rules to ignore these errors, but you should investigate them
first.

Forrest
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