[PATCH 1/5] seccomp: Add find_notification helper

[Tycho Andersen]

On Sun, May 24, 2020 at 04:39:38PM -0700, Sargun Dhillon wrote:
> 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 <sargun at sargun.me>
> Cc: Matt Denton <mpdenton at google.com>
> Cc: Kees Cook <keescook at google.com>,
> Cc: Jann Horn <jannh at google.com>,
> Cc: Robert Sesek <rsesek at google.com>,
> Cc: Chris Palmer <palmer at google.com>
> Cc: Christian Brauner <christian.brauner at ubuntu.com>
> Cc: Tycho Andersen <tycho at tycho.ws>
> ---
>  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;
> +}

I think there's also an instance of this in _send() that we can change
to use find_notification() as well.

Tycho