seccomp: Set PF_SUPERPRIV when checking capability

commit fb14528e443646dd3fd02df4437fcf5265b66baa upstream.

Replace the use of security_capable(current_cred(), ...) with
ns_capable_noaudit() which set PF_SUPERPRIV.

Since commit 98f368e ("kernel: Add noaudit variant of
ns_capable()"), a new ns_capable_noaudit() helper is available.  Let's
use it!

Cc: Jann Horn <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Will Drewry <[email protected]>
Cc: [email protected]
Fixes: e2cfabd ("seccomp: add system call filtering using BPF")
Signed-off-by: Mickaël Salaün <[email protected]>
Reviewed-by: Jann Horn <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

kernel/seccomp.c

@@ -36,7 +36,7 @@
 #include <linux/filter.h>
 #include <linux/pid.h>
 #include <linux/ptrace.h>
-#include <linux/security.h>
+#include <linux/capability.h>
 #include <linux/tracehook.h>
 #include <linux/uaccess.h>
 
@@ -383,8 +383,7 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
 	 * behavior of privileged children.
 	 */
 	if (!task_no_new_privs(current) &&
-	    security_capable(current_cred(), current_user_ns(),
-				     CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0)
+			!ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
 		return ERR_PTR(-EACCES);
 
 	/* Allocate a new seccomp_filter */