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@xxxxxxxxx>
> Cc: Matt Denton <mpdenton@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxx>,
> Cc: Jann Horn <jannh@xxxxxxxxxx>,
> Cc: Robert Sesek <rsesek@xxxxxxxxxx>,
> Cc: Chris Palmer <palmer@xxxxxxxxxx>
> Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
> Cc: Tycho Andersen <tycho@xxxxxxxx>
> ---
> 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;
> +}
> +
> +
> static long seccomp_notify_recv(struct seccomp_filter *filter,
> void __user *buf)
> {
> - struct seccomp_knotif *knotif = NULL, *cur;
> + struct seccomp_knotif *knotif, *cur;
> struct seccomp_notif unotif;
> ssize_t ret;
>
> @@ -1078,14 +1093,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter,
> * may have died when we released the lock, so we need to make
> * sure it's still around.
> */
> - knotif = NULL;
> mutex_lock(&filter->notify_lock);
> - list_for_each_entry(cur, &filter->notif->notifications, list) {
> - if (cur->id == unotif.id) {
> - knotif = cur;
> - break;
> - }
> - }
> + knotif = find_notification(filter, unotif.id);
>
> if (knotif) {
> knotif->state = SECCOMP_NOTIFY_INIT;
> @@ -1150,7 +1159,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter,
> static long seccomp_notify_id_valid(struct seccomp_filter *filter,
> void __user *buf)
> {
> - struct seccomp_knotif *knotif = NULL;
> + struct seccomp_knotif *knotif;
> u64 id;
> long ret;
>
> @@ -1162,15 +1171,10 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter,
> return ret;
>
> ret = -ENOENT;
> - list_for_each_entry(knotif, &filter->notif->notifications, list) {
> - if (knotif->id == id) {
> - if (knotif->state == SECCOMP_NOTIFY_SENT)
> - ret = 0;
> - goto out;
> - }
> - }
> + knotif = find_notification(filter, id);
> + if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
> + ret = 0;
Coul be a little nicer to have this be:
if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
ret = 0;
else
ret = -ENOENT;
or, if you want to keep the assignment out of the lock:
ret = -ENOENT;
ret = mutex_lock_interruptible(&filter->notify_lock);
if (ret < 0)
return ret;
knotif = find_notification(filter, id);
if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
ret = 0;
otherwise looks like a good cleanup to me.
