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On 01/13/2012 03:33 AM, Philippe Naudin wrote:
> Hello,
>
> I have a strange (for me) problem with these two machines : -
> Client, a CentOS-5.7 workstation ; - Server, a CentOS-6.2 headless,
> up-to-date server.
>
>> From Client, I want to use xauth on Server with the help of rsh
>> (yes, I
> know, ssh and all this sort of things... another time.)
>
> When SELinux is in permissive mode on Server, all these commands
> perform as expected : rsh Server /usr/bin/xauth info rsh Server
> /usr/bin/xauth list xauth nextract - Client:0.0 | rsh Server
> /usr/bin/xauth nmerge -
>
> But when SELinux is in enforcing mode on Server, the commands fail
> with this message : bash: /usr/bin/xauth: Permission denied
>
> and /var/log/audit/audit.log shows the following errors :
> type=SELINUX_ERR msg=audit(1326381080.364:610):
> security_compute_sid: invalid context
> system_u:system_r:xauth_t:s0-s0:c0.c1023 for
> scontext=system_u:system_r:unconfined_t:s0-s0:c0.c1023
> tcontext=system_u:object_r:xauth_exec_t:s0 tclass=process
>
> type=AVC msg=audit(1326381080.364:610): avc: denied { write } for
> pid=3487 comm="xauth" path="pipe:[21744]" dev=pipefs ino=21744
> scontext=system_u:system_r:xauth_t:s0-s0:c0.c1023
> tcontext=system_u:system_r:rshd_t:s0-s0:c0.c1023 tclass=fifo_file
>
> type=AVC msg=audit(1326381080.369:611): avc: denied { getattr }
> for pid=3487 comm="xauth" path="socket:[21700]" dev=sockfs
> ino=21700 scontext=system_u:system_r:xauth_t:s0-s0:c0.c1023
> tcontext=system_u:system_r:inetd_t:s0-s0:c0.c1023
> tclass=tcp_socket
>
> The output from audit2allow is here : $ grep AVC
> /var/log/audit/audit.log | audit2allow
> libsepol.context_from_record: invalid security context:
> "system_u:system_r:xauth_t:s0-s0:c0.c1023"
> libsepol.context_from_record: could not create context structure
> libsepol.context_from_string: could not create context structure
> libsepol.sepol_context_to_sid: could not convert
> system_u:system_r:xauth_t:s0-s0:c0.c1023 to sid (these 4 lines are
> repeated 2 times)
>
> On Server, after creating a new authority file (with rsh again,
> while Server is in permissive mode), I find : $ ls -Z .Xauthority
> -rw-------. naudin biom system_u:object_r:xauth_home_t:s0
> .Xauthority
>
> I don't have this problem on a CentOS-5.7 server with the same
> configuration.
>
> Any idea (other than ssh) on how to solve it ?
>
> Thanks,
>
If you add a
policy_module(myxauth, 1.0)
gen_requires(`
type xauth_t;
role system_r;
')
role system_r types xauth_t;
It should fix the first problem, not sure the other two are important.
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