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Re: [RFC][PATCH] collect security labels on user processes generating audit messages



On Thu, 2006-02-16 at 12:03 -0700, Lamont R. Peterson wrote:
> On Wednesday 15 February 2006 10:17am, Linda Knippers wrote:
> > Steve Grubb wrote:
> > > This should be a separate thread since the topic is different.
> > >
> > > On Wednesday 15 February 2006 11:14, Linda Knippers wrote:
> > >>Amy submitted a patch a while back to eliminate the "name=" field
> > >>to avoid "name=(null)" from the audit records if there was no name
> > >>but I don't think the patch went anywhere.
> > >
> > > Right. I want all audit fields to have name=value. If we have %s in the
> > > message and pass NULL to it, snprintf is already going to put "(null)" so
> > > what's wrong with just using this precedent?
> >
> > The problem is that "(null)" is a valid file name.
> >
> > [ljk cert-e2 ~]$ touch "(null)"
> > [ljk cert-e2 ~]$ ls -l "(null)"
> > -rw-rw-r--  1 ljk ljk 0 Feb 17 11:14 (null)
> >
> > When I look at audit records generated by those commands I see records
> > like this:
> >
> > type=SYSCALL msg=audit(1140192875.311:3789): arch=c000003e syscall=132
> > success=yes exit=0 a0=7fbffffc51 a1=0 a2=1b6 a3=0 items=1 pid=2116
> > auid=501 uid=501 gid=501 euid=501 suid=501 fsuid=501 egid=501 sgid=501
> > fsgid=501 comm="touch" exe="/bin/touch"
> > type=CWD msg=audit(1140192875.311:3789):  cwd="/home/ljk"
> > type=PATH msg=audit(1140192875.311:3789): name="(null)" flags=1
> > inode=6537222 dev=fd:01 mode=0100664 ouid=501 ogid=501 rdev=00:00
> >
> > How can I tell from the audit records that the file name was "(null)"
> > vs. having "(null)" manufactured by the audit system?
> 
> How about:
> 
> type=PATH msg=audit(1140192875.311:3789): name=NULL flags=1
> 
> in cases where it truly is NULL?  The double-quotes "" are used to quote 
> file-names and without them, we have some kind of meta-value, instead.
> 
> [snip]

The difference is too subtle.  I imagine that will get confusing.  What
we use to represent a NULL value isn't as important is how we
distinguish it.  For instance, simply encoding "NULL" the filename will
make the distinction between 'name=NULL' and
name="NULL" (name="78857676") , clearer. 

If we "strongly suggest" the admin use ausearch to read the log, then we
could let ausearch make the distinction between quoted and unquoted
NULL's clearer, rather than the kernel.

-tim


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