Sargun Dhillon b71781c589 seccomp: Refactor notification handler to prepare for new semantics ...

commit ddc473916955f7710d1eb17c1273d91c8622a9fe upstream.

This refactors the user notification code to have a do / while loop around
the completion condition. This has a small change in semantic, in that
previously we ignored addfd calls upon wakeup if the notification had been
responded to, but instead with the new change we check for an outstanding
addfd calls prior to returning to userspace.

Rodrigo Campos also identified a bug that can result in addfd causing
an early return, when the supervisor didn't actually handle the
syscall [1].

[1]: https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/

Fixes: 7cf97b1254 ("seccomp: Introduce addfd ioctl to seccomp user notifier")
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Tycho Andersen <tycho@tycho.pizza>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Rodrigo Campos <rodrigo@kinvolk.io>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210517193908.3113-3-sargun@sargun.me
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2021-06-03 09:00:31 +02:00

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