From: Andrei Vagin Date: Fri, 28 Jun 2024 02:10:11 +0000 (+0000) Subject: seccomp: interrupt SECCOMP_IOCTL_NOTIF_RECV when all users have exited X-Git-Tag: v6.11-rc1~181^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=95036a79e7b56178e2fa9c485114be61d24c1695;p=thirdparty%2Fkernel%2Flinux.git seccomp: interrupt SECCOMP_IOCTL_NOTIF_RECV when all users have exited SECCOMP_IOCTL_NOTIF_RECV promptly returns when a seccomp filter becomes unused, as a filter without users can't trigger any events. Previously, event listeners had to rely on epoll to detect when all processes had exited. The change is based on the 'commit 99cdb8b9a573 ("seccomp: notify about unused filter")' which implemented (E)POLLHUP notifications. Reviewed-by: Christian Brauner Signed-off-by: Andrei Vagin Reviewed-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240628021014.231976-2-avagin@google.com Reviewed-by: Tycho Andersen Signed-off-by: Kees Cook --- diff --git a/kernel/seccomp.c b/kernel/seccomp.c index e30b60b57614e..60990264fef0b 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1466,7 +1466,7 @@ static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int s void *key) { /* Avoid a wakeup if event not interesting for us. */ - if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR))) + if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP))) return 0; return autoremove_wake_function(wait, mode, sync, key); } @@ -1476,6 +1476,9 @@ static int recv_wait_event(struct seccomp_filter *filter) DEFINE_WAIT_FUNC(wait, recv_wake_function); int ret; + if (refcount_read(&filter->users) == 0) + return 0; + if (atomic_dec_if_positive(&filter->notif->requests) >= 0) return 0; @@ -1484,6 +1487,8 @@ static int recv_wait_event(struct seccomp_filter *filter) if (atomic_dec_if_positive(&filter->notif->requests) >= 0) break; + if (refcount_read(&filter->users) == 0) + break; if (ret) return ret;