This adds a helper which can iterate through a seccomp_filter to
find a notification matching an ID. It removes several replicated
chunks of code.

Signed-off-by: Sargun Dhillon <redacted>
Cc: Matt Denton <redacted>
Cc: Kees Cook <redacted>,
Cc: Jann Horn <jannh@google.com>,
Cc: Robert Sesek <redacted>,
Cc: Chris Palmer <redacted>
Cc: Christian Brauner <redacted>
Cc: Tycho Andersen <redacted>
---
 kernel/seccomp.c | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 55a6184f5990..f6ce94b7a167 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c

@@ -1021,10 +1021,25 @@ static int seccomp_notify_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+/* must be called with notif_lock held */
+static inline struct seccomp_knotif *
+find_notification(struct seccomp_filter *filter, u64 id)
+{
+	struct seccomp_knotif *cur;
+
+	list_for_each_entry(cur, &filter->notif->notifications, list) {
+		if (cur->id == id)
+			return cur;
+	}
+
+	return NULL;
+}