Re: "security_compute_sid: invalid context" error when starting/stopping mysqld daemon

[Eamon Walsh <ewalsh@tycho.nsa.gov>]

On 11/04/2009 06:57 PM, Larry Ross wrote:
> I have two selinux users that need to be able to stop and start the
> mysql daemon, which is started by the initialization scripts.  When
> the daemon is stopped and started by the secadm_u user, it ends up in
> the context secadm_u:secadm_r:mysqld_t.  When it is stopped and
> started by the dbadm_u user, it ends up in the
> dbadm_u:dbadm_r:mysqld_t context.  When it is started by the init
> scripts it ends up in the system_u:system_r:mysqld_t domain.
>  
> I would like it to alway end up in the system_r:mysqld_t domain, but
> can't seem to find any documentation that describes how to get that to
> work.
>  
> If I add a role_transition rule to transition the role to system_r
> when the executable is run:
> role_transition sysadm_r mysqld_safe_exec_t system_r;
> role_transition dbadm_r  mysqld_safe_exec_t system_r;
> I end up getting these errors:
>  
> Nov  4 15:41:36 localhost kernel: type=1401 audit(1257378096.775:46):
> security_compute_sid:  invalid context
> dbadm_u:system_r:mysqld_safe_t:s0 for
> scontext=dbadm_u:dbadm_r:initrc_t:s0
> tcontext=system_u:object_r:mysqld_safe_exec_t:s0 tclass=process
>  
> I believe I have the rules that should allow this, but obviously I am
> missing something.
> role dbadm_r types mysqld_safe_t;
> role sysadm_r types mysqld_safe_t;
> role system_r types mysqld_safe_t;
> and this:
> allow initrc_t mysqld_safe_t : process transition ;
> which is what the "security_compute_sid" message looks like it is missing.
>  
> Does anyone know where I can find a good description of how to get a
> service to transistion back into system_r when started by a user or
> have any idea what I am missing?


The run_init program was designed to solve this problem, take a look at
the man page.

On Fedora at least, the "service" command calls run_init internally, so
doing "service mysqld start" should in theory start it up in the
system_r role.  If you're just running "/etc/init.d/mysld start" it
won't transition.



-- 

Eamon Walsh 
National Security Agency


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