Merge tag 'kernel.fork.v6.3-rc2' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux

Pull clone3 fix from Christian Brauner:
 "A simple fix for the clone3() system call.

  The CLONE_NEWTIME allows the creation of time namespaces. The flag
  reuses a bit from the CSIGNAL bits that are used in the legacy clone()
  system call to set the signal that gets sent to the parent after the
  child exits.

  The clone3() system call doesn't rely on CSIGNAL anymore as it uses a
  dedicated .exit_signal field in struct clone_args. So we blocked all
  CSIGNAL bits in clone3_args_valid(). When CLONE_NEWTIME was introduced
  and reused a CSIGNAL bit we forgot to adapt clone3_args_valid()
  causing CLONE_NEWTIME with clone3() to be rejected. Fix this"

* tag 'kernel.fork.v6.3-rc2' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux:
  selftests/clone3: test clone3 with CLONE_NEWTIME
  fork: allow CLONE_NEWTIME in clone3 flags

Author: torvalds

kernel/fork.c

@@ -2936,7 +2936,7 @@ static bool clone3_args_valid(struct kernel_clone_args *kargs)
 	 * - make the CLONE_DETACHED bit reusable for clone3
 	 * - make the CSIGNAL bits reusable for clone3
 	 */
-	if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
+	if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
 		return false;
 
 	if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==

tools/testing/selftests/clone3/clone3.c

@@ -195,5 +195,8 @@ int main(int argc, char *argv[])
 	test_clone3(CLONE_NEWPID, getpagesize() + 8, -E2BIG,
 			CLONE3_ARGS_NO_TEST);
 
+	/* Do a clone3() in a new time namespace */
+	test_clone3(CLONE_NEWTIME, 0, 0, CLONE3_ARGS_NO_TEST);
+
 	return !ksft_get_fail_cnt() ? ksft_exit_pass() : ksft_exit_fail();
 }