audit-viewer "comm" question

audit-viewer "comm" question

[LC Bruzenak]

After reading Steve's info about the "comm" field being clipped at 16
chars, I was surprised to see a longer string inside the audit-viewer
"comm" field.
I have taken a screen shot, but won't post it unless asked (it's 41K).
The "comm" field there is: "/usr/libexec/gnome-settings-daemon", which
of course is longer than 16 chars.

The same event in ausearch shows a NULL "comm" field, but the rest of
the info lines up with the GUI:

[root@hugo ~]# ausearch -ts today -i -a 126492
----
type=USER_AVC msg=audit(08/04/2008 16:04:24.152:126492) : user pid=23501
uid=root auid=unset subj=system_u:system_r:xdm_xserver_t:s0-s15:c0.c1023
msg='avc:  denied  { receive } for  comm=(null) event=X11:PropertyNotify
scontext=user_u:user_r:user_t:s0-s15:c0.c1023
tcontext=user_u:object_r:property_xevent_t:s4:c0,c2,c11,c200.c511
tclass=x_event : exe=/usr/bin/Xorg (sauid=root  hostname=?, addr=?,
terminal=?)' 

-- 
LC (Lenny) Bruzenak
lenny@magitekltd.com

Re: audit-viewer "comm" question

[LC Bruzenak]

On Mon, 2008-08-04 at 17:49 -0500, LC Bruzenak wrote:
> After reading Steve's info about the "comm" field being clipped at 16
> chars, I was surprised to see a longer string inside the audit-viewer
> "comm" field.
> I have taken a screen shot, but won't post it unless asked (it's 41K).
> The "comm" field there is: "/usr/libexec/gnome-settings-daemon", which
> of course is longer than 16 chars.
> 
> The same event in ausearch shows a NULL "comm" field, but the rest of
> the info lines up with the GUI:
> 
> [root@hugo ~]# ausearch -ts today -i -a 126492
> ----
> type=USER_AVC msg=audit(08/04/2008 16:04:24.152:126492) : user pid=23501
> uid=root auid=unset subj=system_u:system_r:xdm_xserver_t:s0-s15:c0.c1023
> msg='avc:  denied  { receive } for  comm=(null) event=X11:PropertyNotify
> scontext=user_u:user_r:user_t:s0-s15:c0.c1023
> tcontext=user_u:object_r:property_xevent_t:s4:c0,c2,c11,c200.c511
> tclass=x_event : exe=/usr/bin/Xorg (sauid=root  hostname=?, addr=?,
> terminal=?)' 
> 

I guess the question here is not why there is > 16 chars (since this is
a USER_AVC not kernel-generated event - right?) but rather why the GUI
shows the comm but the ausearch doesn't.
 
Thx,
LCB.

-- 
LC (Lenny) Bruzenak
lenny@magitekltd.com

Re: audit-viewer "comm" question

[Steve Grubb]

On Monday 04 August 2008 18:49:42 LC Bruzenak wrote:
> After reading Steve's info about the "comm" field being clipped at 16
> chars, I was surprised to see a longer string inside the audit-viewer
> "comm" field.

If the event below is where it came from, then it originated in user space and 
is not subject to the 16 byte kernel limitation.

> The same event in ausearch shows a NULL "comm" field, but the rest of
> the info lines up with the GUI:

The user space AVCs are FUBAR and I told the SE Linux people that they are not 
following the audit logging convention. They need to fix the code in 
libselinux.

-Steve

Re: audit-viewer "comm" question

[Steve Grubb]

On Monday 04 August 2008 19:01:43 LC Bruzenak wrote:
> > type=USER_AVC msg=audit(08/04/2008 16:04:24.152:126492) : user pid=23501
> > uid=root auid=unset subj=system_u:system_r:xdm_xserver_t:s0-s15:c0.c1023
> > msg='avc:  denied  { receive } for  comm=(null) event=X11:PropertyNotify
> > scontext=user_u:user_r:user_t:s0-s15:c0.c1023
> > tcontext=user_u:object_r:property_xevent_t:s4:c0,c2,c11,c200.c511
> > tclass=x_event : exe=/usr/bin/Xorg (sauid=root  hostname=?, addr=?,
> > terminal=?)'
>
> I guess the question here is not why there is > 16 chars (since this is
> a USER_AVC not kernel-generated event - right?)

Yep.

> but rather why the GUI shows the comm but the ausearch doesn't.

I think I tried to work around the problem the SE Linux folks are creating and 
then decided they need to fix the code since I am now violating the audit 
standard by allowing for the mis-use of field encoding. They should probably 
both show (null) until this gets fixing in libselinux.

-Steve