Commit 9f87dcf1 authored by Sargun Dhillon's avatar Sargun Dhillon Committed by Kees Cook
Browse files

seccomp: Add find_notification helper 



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: default avatarSargun Dhillon <sargun@sargun.me>
Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: default avatarTycho Andersen <tycho@tycho.ws>
Cc: Matt Denton <mpdenton@google.com>
Cc: Kees Cook <keescook@google.com>,
Cc: Jann Horn <jannh@google.com>,
Cc: Robert Sesek <rsesek@google.com>,
Cc: Chris Palmer <palmer@google.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Tycho Andersen <tycho@tycho.ws>
Link: https://lore.kernel.org/r/20200601112532.150158-1-sargun@sargun.me


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent c818c03b

kernel/seccomp.c

+27 −26
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include <linux/tracehook.h>

#include <linux/uaccess.h>

#include <linux/anon_inodes.h>

#include <linux/lockdep.h>



enum notify_state {

	SECCOMP_NOTIFY_INIT,
@@ -1024,6 +1025,23 @@ 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;



	lockdep_assert_held(&filter->notify_lock);



	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)

{
@@ -1081,15 +1099,8 @@ 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;

			up(&filter->notif->request);
@@ -1104,7 +1115,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, 
				void __user *buf)

{

	struct seccomp_notif_resp resp = {};

	struct seccomp_knotif *knotif = NULL, *cur;

	struct seccomp_knotif *knotif;

	long ret;



	if (copy_from_user(&resp, buf, sizeof(resp)))
@@ -1121,13 +1132,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, 
	if (ret < 0)

		return ret;



	list_for_each_entry(cur, &filter->notif->notifications, list) {

		if (cur->id == resp.id) {

			knotif = cur;

			break;

		}

	}



	knotif = find_notification(filter, resp.id);

	if (!knotif) {

		ret = -ENOENT;

		goto out;
@@ -1153,7 +1158,7 @@ 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;
@@ -1164,16 +1169,12 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, 
	if (ret < 0)

		return ret;



	ret = -ENOENT;

	list_for_each_entry(knotif, &filter->notif->notifications, list) {

		if (knotif->id == id) {

			if (knotif->state == SECCOMP_NOTIFY_SENT)

	knotif = find_notification(filter, id);

	if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)

		ret = 0;

			goto out;

		}

	}

	else

		ret = -ENOENT;



out:

	mutex_unlock(&filter->notify_lock);

	return ret;

}