38 #include <linux/filter.h>
62 	/* The struct pid of the task whose filter triggered the notification */
65 	/* The "cookie" for this request; this is unique for this filter. */
136  *           filter->notify_lock.
150  *	  A filter's reference count is incremented for each directly
151  *	  attached task, once for the dependent filter, and if
153  *	  the filter can be freed.
154  * @users: A filter's @users count is incremented for each directly
155  *         attached task (filter installation, fork(), thread_sync),
156  *	   and once for the dependent filter (tracked in filter->prev).
158  *	   users of that filter exist. No new tasks can get associated with
159  *	   this filter after reaching 0. The @users count is always smaller
161  *	   the filter can be freed.
163  * @prev: points to a previously installed, or inherited, filter
171  * with current->seccomp.filter, the most recently attached or inherited filter.
220  *	seccomp_check_filter - verify seccomp filter code
221  *	@filter: filter to verify
222  *	@flen: length of filter
224  * Takes a previously checked filter (by bpf_check_classic) and
225  * redirects all filter code that loads struct sk_buff data
231 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)  in seccomp_check_filter()  argument
235 		struct sock_filter *ftest = &filter[pc];  in seccomp_check_filter()
305  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
315 	/* Make sure cross-thread synced filter points somewhere sane. */  in seccomp_run_filters()
317 			READ_ONCE(current->seccomp.filter);  in seccomp_run_filters()
360 	 * filter) is set.  in seccomp_assign_mode()
390  * seccomp filter.
410 		     is_ancestor(thread->seccomp.filter,  in seccomp_can_sync_threads()
411 				 caller->seccomp.filter)))  in seccomp_can_sync_threads()
425 static inline void seccomp_filter_free(struct seccomp_filter *filter)  in seccomp_filter_free()  argument
427 	if (filter) {  in seccomp_filter_free()
428 		bpf_prog_destroy(filter->prog);  in seccomp_filter_free()
429 		kfree(filter);  in seccomp_filter_free()
454 	/* Notify about any unused filters in the task's former filter tree. */  in __seccomp_filter_release()
461  * seccomp_filter_release - Detach the task from its filter tree,
466  * it detaches it from its filter tree. As such, READ_ONCE() and
471 	struct seccomp_filter *orig = tsk->seccomp.filter;  in seccomp_filter_release()
473 	/* Detach task from its filter tree. */  in seccomp_filter_release()
474 	tsk->seccomp.filter = NULL;  in seccomp_filter_release()
479  * seccomp_sync_threads: sets all threads to use current's filter
508 		__seccomp_filter_release(thread->seccomp.filter);  in seccomp_sync_threads()
510 		/* Make our new filter tree visible. */  in seccomp_sync_threads()
511 		smp_store_release(&thread->seccomp.filter,  in seccomp_sync_threads()
512 				  caller->seccomp.filter);  in seccomp_sync_threads()
538  * seccomp_prepare_filter: Prepares a seccomp filter for use.
541  * Returns filter on success or an ERR_PTR on failure.
555 	 * Installing a seccomp filter requires that the task has  in seccomp_prepare_filter()
594 	struct seccomp_filter *filter = ERR_PTR(-EFAULT);  in seccomp_prepare_user_filter()  local
602 		fprog.filter = compat_ptr(fprog32.filter);  in seccomp_prepare_user_filter()
607 	filter = seccomp_prepare_filter(&fprog);  in seccomp_prepare_user_filter()
609 	return filter;  in seccomp_prepare_user_filter()
613  * seccomp_attach_filter: validate and attach filter
614  * @flags:  flags to change filter behavior
615  * @filter: seccomp filter to add to the current process
621  *     seccomp mode or did not have an ancestral seccomp filter
625 				  struct seccomp_filter *filter)  in seccomp_attach_filter()  argument
632 	/* Validate resulting filter length. */  in seccomp_attach_filter()
633 	total_insns = filter->prog->len;  in seccomp_attach_filter()
634 	for (walker = current->seccomp.filter; walker; walker = walker->prev)  in seccomp_attach_filter()
654 		filter->log = true;  in seccomp_attach_filter()
657 	 * If there is an existing filter, make it the prev and don't drop its  in seccomp_attach_filter()
660 	filter->prev = current->seccomp.filter;  in seccomp_attach_filter()
661 	current->seccomp.filter = filter;  in seccomp_attach_filter()
664 	/* Now that the new filter is in place, synchronize to all threads. */  in seccomp_attach_filter()
671 static void __get_seccomp_filter(struct seccomp_filter *filter)  in __get_seccomp_filter()  argument
673 	refcount_inc(&filter->refs);  in __get_seccomp_filter()
676 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
679 	struct seccomp_filter *orig = tsk->seccomp.filter;  in get_seccomp_filter()
700  * @reason: filter-supplied reason code to send to userland (via si_errno)
821 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)  in seccomp_next_notify_id()  argument
825 	 * filter.  in seccomp_next_notify_id()
827 	lockdep_assert_held(&filter->notify_lock);  in seccomp_next_notify_id()
828 	return filter->notif->next_id++;  in seccomp_next_notify_id()
956 		/* Let the filter pass back 16 bits of data. */  in __seccomp_filter()
1015 		 * Note that the "match" filter will always be NULL for  in __seccomp_filter()
1115 static void seccomp_notify_free(struct seccomp_filter *filter)  in seccomp_notify_free()  argument
1117 	kfree(filter->notif);  in seccomp_notify_free()
1118 	filter->notif = NULL;  in seccomp_notify_free()
1121 static void seccomp_notify_detach(struct seccomp_filter *filter)  in seccomp_notify_detach()  argument
1125 	if (!filter)  in seccomp_notify_detach()
1128 	mutex_lock(&filter->notify_lock);  in seccomp_notify_detach()
1134 	list_for_each_entry(knotif, &filter->notif->notifications, list) {  in seccomp_notify_detach()
1150 	seccomp_notify_free(filter);  in seccomp_notify_detach()
1151 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_detach()
1156 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_release()  local
1158 	seccomp_notify_detach(filter);  in seccomp_notify_release()
1159 	__put_seccomp_filter(filter);  in seccomp_notify_release()
1165 find_notification(struct seccomp_filter *filter, u64 id)  in find_notification()  argument
1169 	lockdep_assert_held(&filter->notify_lock);  in find_notification()
1171 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in find_notification()
1180 static long seccomp_notify_recv(struct seccomp_filter *filter,  in seccomp_notify_recv()  argument
1196 	ret = down_interruptible(&filter->notif->request);  in seccomp_notify_recv()
1200 	mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1201 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_recv()
1223 	wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);  in seccomp_notify_recv()
1226 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1237 		mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1238 		knotif = find_notification(filter, unotif.id);  in seccomp_notify_recv()
1241 			up(&filter->notif->request);  in seccomp_notify_recv()
1243 		mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1249 static long seccomp_notify_send(struct seccomp_filter *filter,  in seccomp_notify_send()  argument
1266 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_send()
1270 	knotif = find_notification(filter, resp.id);  in seccomp_notify_send()
1289 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_send()
1293 static long seccomp_notify_id_valid(struct seccomp_filter *filter,  in seccomp_notify_id_valid()  argument
1303 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_id_valid()
1307 	knotif = find_notification(filter, id);  in seccomp_notify_id_valid()
1313 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_id_valid()
1317 static long seccomp_notify_addfd(struct seccomp_filter *filter,  in seccomp_notify_addfd()  argument
1354 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_addfd()
1358 	knotif = find_notification(filter, addfd.id);  in seccomp_notify_addfd()
1376 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1392 	mutex_lock(&filter->notify_lock);  in seccomp_notify_addfd()
1406 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1416 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_ioctl()  local
1422 		return seccomp_notify_recv(filter, buf);  in seccomp_notify_ioctl()
1424 		return seccomp_notify_send(filter, buf);  in seccomp_notify_ioctl()
1427 		return seccomp_notify_id_valid(filter, buf);  in seccomp_notify_ioctl()
1434 		return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));  in seccomp_notify_ioctl()
1443 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_poll()  local
1447 	poll_wait(file, &filter->wqh, poll_tab);  in seccomp_notify_poll()
1449 	if (mutex_lock_interruptible(&filter->notify_lock) < 0)  in seccomp_notify_poll()
1452 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_poll()
1461 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_poll()
1463 	if (refcount_read(&filter->users) == 0)  in seccomp_notify_poll()
1476 static struct file *init_listener(struct seccomp_filter *filter)  in init_listener()  argument
1481 	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);  in init_listener()
1482 	if (!filter->notif)  in init_listener()
1485 	sema_init(&filter->notif->request, 0);  in init_listener()
1486 	filter->notif->next_id = get_random_u64();  in init_listener()
1487 	INIT_LIST_HEAD(&filter->notif->notifications);  in init_listener()
1490 				 filter, O_RDWR);  in init_listener()
1495 	__get_seccomp_filter(filter);  in init_listener()
1499 		seccomp_notify_free(filter);  in init_listener()
1506  * If so, we'll want to reject this filter.
1510  * we use current->seccomp.filter.
1521 	for (cur = current->seccomp.filter; cur; cur = cur->prev) {  in has_duplicate_listener()
1530  * seccomp_set_mode_filter: internal function for setting seccomp filter
1531  * @flags:  flags to change filter behavior
1532  * @filter: struct sock_fprog containing filter
1535  * Every filter successfully installed will be evaluated (in reverse order)
1543 				    const char __user *filter)  in seccomp_set_mode_filter()  argument
1567 	/* Prepare the new filter before holding any locks. */  in seccomp_set_mode_filter()
1568 	prepared = seccomp_prepare_user_filter(filter);  in seccomp_set_mode_filter()
1608 	/* Do not free the successfully attached filter. */  in seccomp_set_mode_filter()
1634 					   const char __user *filter)  in seccomp_set_mode_filter()  argument
1713  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1717 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)  in prctl_set_seccomp()  argument
1726 		 * Setting strict mode through prctl always ignored filter,  in prctl_set_seccomp()
1734 		uargs = filter;  in prctl_set_seccomp()
1748 	struct seccomp_filter *orig, *filter;  in get_nth_filter()  local
1762 	orig = task->seccomp.filter;  in get_nth_filter()
1767 	for (filter = orig; filter; filter = filter->prev)  in get_nth_filter()
1771 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
1776 	for (filter = orig; filter && count > 1; filter = filter->prev)  in get_nth_filter()
1779 	if (WARN_ON(count != 1 || !filter)) {  in get_nth_filter()
1780 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
1784 	__get_seccomp_filter(filter);  in get_nth_filter()
1788 	return filter;  in get_nth_filter()
1794 	struct seccomp_filter *filter;  in seccomp_get_filter()  local
1803 	filter = get_nth_filter(task, filter_off);  in seccomp_get_filter()
1804 	if (IS_ERR(filter))  in seccomp_get_filter()
1805 		return PTR_ERR(filter);  in seccomp_get_filter()
1807 	fprog = filter->prog->orig_prog;  in seccomp_get_filter()
1809 		/* This must be a new non-cBPF filter, since we save  in seccomp_get_filter()
1810 		 * every cBPF filter's orig_prog above when  in seccomp_get_filter()
1821 	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))  in seccomp_get_filter()
1825 	__put_seccomp_filter(filter);  in seccomp_get_filter()
1833 	struct seccomp_filter *filter;  in seccomp_get_metadata()  local
1849 	filter = get_nth_filter(task, kmd.filter_off);  in seccomp_get_metadata()
1850 	if (IS_ERR(filter))  in seccomp_get_metadata()
1851 		return PTR_ERR(filter);  in seccomp_get_metadata()
1853 	if (filter->log)  in seccomp_get_metadata()
1860 	__put_seccomp_filter(filter);  in seccomp_get_metadata()