open() syscall and success=0 question

[Keith Kaple]

Thanks Steve,

Can you ellaborate a little on EPERM vs. EACCES?

Say a normal user tries to cp /etc/passwd and gets "permission denied" in the shell, will exit=-EPERM or -EACCESS? 

I assume there will be an entry for both if perhaps success=0 alone is used..


Keith




On Tue, May 13, 2008 at 10:24:41AM -0400, Steve Grubb wrote:
> On Tuesday 13 May 2008 10:13:53 Keith Kaple wrote:
> > When open fails, the open() manpage says it will return -1 so that will make
> > success false or 0.  When success is false, auditd seems to use the negated
> > value of ERRNO to populate the exit= field, is that correct?
> 
> This is actually done by the kernel, not auditd. But you are correct.
> 
> > So a rule such as:
> >
> > auditctl -a exit,always -S open -F success=0 -F exit=-13
> >
> > Would log only permission related failures, correct?
> 
> Correct. But that can be reduced to:
> 
> auditctl -a exit,always -S open -F exit=-EPERM
> 
> Syscall rules affect every single syscall made by every program. So, you want 
> the rule to be efficient. In this case, checking the success field is 
> redundant.
> 
> -Steve

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