[PATCH] Allow ppid filtering on syscall auditing

[Eric Paris <eparis@redhat.com>]

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