linux-kernel - Re: [PATCH V4 (was V6)] audit: save signal match info in case entry passed in is the one deleted

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Message-ID: <20150805092536.GF32407@madcap2.tricolour.ca>
Date:	Wed, 5 Aug 2015 05:25:36 -0400
From:	Richard Guy Briggs <rgb@...hat.com>
To:	Paul Moore <pmoore@...hat.com>
Cc:	linux-audit@...hat.com, linux-kernel@...r.kernel.org,
	sgrubb@...hat.com, eparis@...hat.com
Subject: Re: [PATCH V4 (was V6)] audit: save signal match info in case entry
 passed in is the one deleted

On 15/08/04, Paul Moore wrote:
> On Saturday, August 01, 2015 03:44:01 PM Richard Guy Briggs wrote:
> > Move the access to the entry for audit_match_signal() to the beginning of
> > the function in case the entry found is the same one passed in.  This will
> > enable it to be used by audit_remove_mark_rule().
> > 
> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > ---
> >  kernel/auditfilter.c |    3 ++-
> >  1 files changed, 2 insertions(+), 1 deletions(-)
> > 
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index 4cb9b44..afb63b3 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -943,6 +943,7 @@ static inline int audit_del_rule(struct audit_entry
> > *entry) int ret = 0;
> >  #ifdef CONFIG_AUDITSYSCALL
> >  	int dont_count = 0;
> > +	int match_signal = !audit_match_signal(entry);
> > 
> >  	/* If either of these, don't count towards total */
> >  	if (entry->rule.listnr == AUDIT_FILTER_USER ||
> > @@ -972,7 +973,7 @@ static inline int audit_del_rule(struct audit_entry
> > *entry) if (!dont_count)
> >  		audit_n_rules--;
> > 
> > -	if (!audit_match_signal(entry))
> > +	if (match_signal)
> >  		audit_signals--;
> >  #endif
> >  	mutex_unlock(&audit_filter_mutex);
> 
> Why not simply move this second CONFIG_AUDITSYSCALL above the list_del() 
> calls?  Am I missing something?

Good point.  That did occur to me at one point when I wasn't in front of
the code and promptly forgot once I was.  That will neatly remove the
temporary variable.

> Also, while we're fixing up audit_del_rule(), why not also move the 
> mutex_unlock() call to after the "out" jump target and then drop the 
> mutex_unlock() call in the audit_find_rule() error case?  Not your fault, but 
> the code seems silly as-is.

Yes, agreed.  Another nice catch.

These changes will affect "audit by executable" so I'll re-spin that
patch set to make it easier to apply.

> paul moore

- RGB

--
Richard Guy Briggs <rbriggs@...hat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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