[PATCH] Allow ppid filtering on syscall auditing

[Linda Knippers]

Eric Paris wrote:
> Currently ppid filtering on syscall auditing does not appear to work. An
> easy reproducer would be to do the following:
> 
> touch ./test
> auditctl -a entry,always -S chmod -F ppid=[pid of your shell]
> chmod 000 ./test
> 
> no audit record will appear! (although !=[pid of your shell] will show
> all chmod commands from all processes regardless of the ppid)
> 
> With a little instrumentation I found that ctx->ppid == 0 inside
> audit_filter_rules().  I originally wanted to set the ppid during the
> context creation back in something like audit_alloc_context but that
> didn't work.  Because at that point the new process had not forked off
> so the ppid of the chmod process was actually it's parents parents.
> Instead I set the ppid in  audit_syscall_entry when we are actually
> building the specific context.
> 
> Please comment/ack/nak as soon as possible.
> 
> -Eric
> 
>  kernel/auditsc.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> --- linux-2.6.18.i686/kernel/auditsc.c.orig	2006-09-27 21:53:44.000000000 -0400
> +++ linux-2.6.18.i686/kernel/auditsc.c	2006-09-27 21:54:05.000000000 -0400
> @@ -1116,6 +1116,7 @@ void audit_syscall_entry(int arch, int m
>  
>  	context->arch	    = arch;
>  	context->major      = major;
> +	context->ppid       = sys_getppid();

It looks like context->ppid is also being set in audit_log_exit(),
which could overwrite the value assigned here.  Should the one
in audit_log_exit() be removed?

>  	context->argv[0]    = a1;
>  	context->argv[1]    = a2;
>  	context->argv[2]    = a3;
> 
> 
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