Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace

On Tue, Oct 30, 2018 at 05:39:26PM +0100, Oleg Nesterov wrote:

On 10/30, Oleg Nesterov wrote:

quoted

On 10/30, Tycho Andersen wrote:

quoted

@@ -828,6 +823,11 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 	 */
 	rmb();

+	if (!sd) {
+		populate_seccomp_data(&sd_local);
+		sd = &sd_local;
+	}
+

To me it would be more clean to remove the "if (!sd)" check, case(SECCOMP_RET_TRACE)
in __seccomp_filter() can simply do populate_seccomp_data(&sd_local) unconditionally
and pass &sd_local to __seccomp_filter().

Ah, please ignore, emulate_vsyscall() does secure_computing(NULL).

Btw. why __seccomp_filter() doesn't return a boolean?

Or at least, why can't case(SECCOMP_RET_TRACE) simply do

	return __seccomp_filter(this_syscall, NULL, true);

?

Yeah, at least the second one definitely makes sense. I can add that
as a patch in the next version of this series unless Kees does it
before.

Thanks for your help, Oleg!

Tycho