39 #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. */
143  *            filter->notify_lock.
158  * struct action_cache - per-filter cache of seccomp actions per
162  *		  filter will always allow the syscall, for the
165  *		  filter will always allow the syscall, for the
192  *	  A filter's reference count is incremented for each directly
193  *	  attached task, once for the dependent filter, and if
195  *	  the filter can be freed.
196  * @users: A filter's @users count is incremented for each directly
197  *         attached task (filter installation, fork(), thread_sync),
198  *	   and once for the dependent filter (tracked in filter->prev).
200  *	   users of that filter exist. No new tasks can get associated with
201  *	   this filter after reaching 0. The @users count is always smaller
203  *	   the filter can be freed.
208  * @prev: points to a previously installed, or inherited, filter
216  * with current->seccomp.filter, the most recently attached or inherited filter.
267  *	seccomp_check_filter - verify seccomp filter code
268  *	@filter: filter to verify
269  *	@flen: length of filter
271  * Takes a previously checked filter (by bpf_check_classic) and
272  * redirects all filter code that loads struct sk_buff data
278 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)  in seccomp_check_filter()  argument
282 		struct sock_filter *ftest = &filter[pc];  in seccomp_check_filter()
362  * @sfilter: The seccomp filter
399  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
408 	/* Make sure cross-thread synced filter points somewhere sane. */  in seccomp_run_filters()
410 			READ_ONCE(current->seccomp.filter);  in seccomp_run_filters()
456 	 * filter) is set.  in seccomp_assign_mode()
486  * seccomp filter.
509 		     is_ancestor(thread->seccomp.filter,  in seccomp_can_sync_threads()
510 				 caller->seccomp.filter)))  in seccomp_can_sync_threads()
524 static inline void seccomp_filter_free(struct seccomp_filter *filter)  in seccomp_filter_free()  argument
526 	if (filter) {  in seccomp_filter_free()
527 		bpf_prog_destroy(filter->prog);  in seccomp_filter_free()
528 		kfree(filter);  in seccomp_filter_free()
553 	/* Notify about any unused filters in the task's former filter tree. */  in __seccomp_filter_release()
560  * seccomp_filter_release - Detach the task from its filter tree,
564  * @tsk: task the filter should be released from.
567  * it detaches it from its filter tree. PF_EXITING has to be set
577 	if (READ_ONCE(tsk->seccomp.filter) == NULL)  in seccomp_filter_release()
581 	orig = tsk->seccomp.filter;  in seccomp_filter_release()
582 	/* Detach task from its filter tree. */  in seccomp_filter_release()
583 	tsk->seccomp.filter = NULL;  in seccomp_filter_release()
589  * seccomp_sync_threads: sets all threads to use current's filter
634 		__seccomp_filter_release(thread->seccomp.filter);  in seccomp_sync_threads()
636 		/* Make our new filter tree visible. */  in seccomp_sync_threads()
637 		smp_store_release(&thread->seccomp.filter,  in seccomp_sync_threads()
638 				  caller->seccomp.filter);  in seccomp_sync_threads()
664  * seccomp_prepare_filter: Prepares a seccomp filter for use.
667  * Returns filter on success or an ERR_PTR on failure.
686 	 * Installing a seccomp filter requires that the task has  in seccomp_prepare_filter()
725 	struct seccomp_filter *filter = ERR_PTR(-EFAULT);  in seccomp_prepare_user_filter()  local
733 		fprog.filter = compat_ptr(fprog32.filter);  in seccomp_prepare_user_filter()
738 	filter = seccomp_prepare_filter(&fprog);  in seccomp_prepare_user_filter()
740 	return filter;  in seccomp_prepare_user_filter()
745  * seccomp_is_const_allow - check if filter is constant allow with given data
770 		struct sock_filter *insn = &fprog->filter[pc];  in seccomp_is_const_allow()
827 	/* ran off the end of the filter?! */  in seccomp_is_const_allow()
841 		/* The new filter must be as restrictive as the last. */  in seccomp_cache_prepare_bitmap()
862 		 * atomic clear_bit() not needed, filter not visible yet.  in seccomp_cache_prepare_bitmap()
869  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
870  * @sfilter: The seccomp filter
895  * seccomp_attach_filter: validate and attach filter
896  * @flags:  flags to change filter behavior
897  * @filter: seccomp filter to add to the current process
903  *     seccomp mode or did not have an ancestral seccomp filter
907 				  struct seccomp_filter *filter)  in seccomp_attach_filter()  argument
914 	/* Validate resulting filter length. */  in seccomp_attach_filter()
915 	total_insns = filter->prog->len;  in seccomp_attach_filter()
916 	for (walker = current->seccomp.filter; walker; walker = walker->prev)  in seccomp_attach_filter()
936 		filter->log = true;  in seccomp_attach_filter()
940 		filter->wait_killable_recv = true;  in seccomp_attach_filter()
943 	 * If there is an existing filter, make it the prev and don't drop its  in seccomp_attach_filter()
946 	filter->prev = current->seccomp.filter;  in seccomp_attach_filter()
947 	seccomp_cache_prepare(filter);  in seccomp_attach_filter()
948 	current->seccomp.filter = filter;  in seccomp_attach_filter()
951 	/* Now that the new filter is in place, synchronize to all threads. */  in seccomp_attach_filter()
958 static void __get_seccomp_filter(struct seccomp_filter *filter)  in __get_seccomp_filter()  argument
960 	refcount_inc(&filter->refs);  in __get_seccomp_filter()
963 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
966 	struct seccomp_filter *orig = tsk->seccomp.filter;  in get_seccomp_filter()
1095 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)  in seccomp_next_notify_id()  argument
1099 	 * filter.  in seccomp_next_notify_id()
1101 	lockdep_assert_held(&filter->notify_lock);  in seccomp_next_notify_id()
1102 	return filter->notif->next_id++;  in seccomp_next_notify_id()
1274 		/* Let the filter pass back 16 bits of data. */  in __seccomp_filter()
1333 		 * Note that the "match" filter will always be NULL for  in __seccomp_filter()
1435 static void seccomp_notify_free(struct seccomp_filter *filter)  in seccomp_notify_free()  argument
1437 	kfree(filter->notif);  in seccomp_notify_free()
1438 	filter->notif = NULL;  in seccomp_notify_free()
1441 static void seccomp_notify_detach(struct seccomp_filter *filter)  in seccomp_notify_detach()  argument
1445 	if (!filter)  in seccomp_notify_detach()
1448 	mutex_lock(&filter->notify_lock);  in seccomp_notify_detach()
1454 	list_for_each_entry(knotif, &filter->notif->notifications, list) {  in seccomp_notify_detach()
1470 	seccomp_notify_free(filter);  in seccomp_notify_detach()
1471 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_detach()
1476 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_release()  local
1478 	seccomp_notify_detach(filter);  in seccomp_notify_release()
1479 	__put_seccomp_filter(filter);  in seccomp_notify_release()
1485 find_notification(struct seccomp_filter *filter, u64 id)  in find_notification()  argument
1489 	lockdep_assert_held(&filter->notify_lock);  in find_notification()
1491 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in find_notification()
1508 static int recv_wait_event(struct seccomp_filter *filter)  in recv_wait_event()  argument
1513 	if (refcount_read(&filter->users) == 0)  in recv_wait_event()
1516 	if (atomic_dec_if_positive(&filter->notif->requests) >= 0)  in recv_wait_event()
1520 		ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);  in recv_wait_event()
1522 		if (atomic_dec_if_positive(&filter->notif->requests) >= 0)  in recv_wait_event()
1524 		if (refcount_read(&filter->users) == 0)  in recv_wait_event()
1532 	finish_wait(&filter->wqh, &wait);  in recv_wait_event()
1536 static long seccomp_notify_recv(struct seccomp_filter *filter,  in seccomp_notify_recv()  argument
1552 	ret = recv_wait_event(filter);  in seccomp_notify_recv()
1556 	mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1557 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_recv()
1579 	wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);  in seccomp_notify_recv()
1582 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1593 		mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1594 		knotif = find_notification(filter, unotif.id);  in seccomp_notify_recv()
1597 			if (should_sleep_killable(filter, knotif))  in seccomp_notify_recv()
1600 			atomic_inc(&filter->notif->requests);  in seccomp_notify_recv()
1601 			wake_up_poll(&filter->wqh, EPOLLIN | EPOLLRDNORM);  in seccomp_notify_recv()
1603 		mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1609 static long seccomp_notify_send(struct seccomp_filter *filter,  in seccomp_notify_send()  argument
1626 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_send()
1630 	knotif = find_notification(filter, resp.id);  in seccomp_notify_send()
1647 	if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)  in seccomp_notify_send()
1652 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_send()
1656 static long seccomp_notify_id_valid(struct seccomp_filter *filter,  in seccomp_notify_id_valid()  argument
1666 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_id_valid()
1670 	knotif = find_notification(filter, id);  in seccomp_notify_id_valid()
1676 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_id_valid()
1680 static long seccomp_notify_set_flags(struct seccomp_filter *filter,  in seccomp_notify_set_flags()  argument
1688 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_set_flags()
1691 	filter->notif->flags = flags;  in seccomp_notify_set_flags()
1692 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_set_flags()
1696 static long seccomp_notify_addfd(struct seccomp_filter *filter,  in seccomp_notify_addfd()  argument
1734 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_addfd()
1738 	knotif = find_notification(filter, addfd.id);  in seccomp_notify_addfd()
1773 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1789 	mutex_lock(&filter->notify_lock);  in seccomp_notify_addfd()
1803 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1813 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_ioctl()  local
1819 		return seccomp_notify_recv(filter, buf);  in seccomp_notify_ioctl()
1821 		return seccomp_notify_send(filter, buf);  in seccomp_notify_ioctl()
1824 		return seccomp_notify_id_valid(filter, buf);  in seccomp_notify_ioctl()
1826 		return seccomp_notify_set_flags(filter, arg);  in seccomp_notify_ioctl()
1833 		return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));  in seccomp_notify_ioctl()
1842 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_poll()  local
1846 	poll_wait(file, &filter->wqh, poll_tab);  in seccomp_notify_poll()
1848 	if (mutex_lock_interruptible(&filter->notify_lock) < 0)  in seccomp_notify_poll()
1851 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_poll()
1860 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_poll()
1862 	if (refcount_read(&filter->users) == 0)  in seccomp_notify_poll()
1875 static struct file *init_listener(struct seccomp_filter *filter)  in init_listener()  argument
1880 	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);  in init_listener()
1881 	if (!filter->notif)  in init_listener()
1884 	filter->notif->next_id = get_random_u64();  in init_listener()
1885 	INIT_LIST_HEAD(&filter->notif->notifications);  in init_listener()
1888 				 filter, O_RDWR);  in init_listener()
1893 	__get_seccomp_filter(filter);  in init_listener()
1897 		seccomp_notify_free(filter);  in init_listener()
1904  * If so, we'll want to reject this filter.
1908  * we use current->seccomp.filter.
1919 	for (cur = current->seccomp.filter; cur; cur = cur->prev) {  in has_duplicate_listener()
1928  * seccomp_set_mode_filter: internal function for setting seccomp filter
1929  * @flags:  flags to change filter behavior
1930  * @filter: struct sock_fprog containing filter
1933  * Every filter successfully installed will be evaluated (in reverse order)
1941 				    const char __user *filter)  in seccomp_set_mode_filter()  argument
1973 	/* Prepare the new filter before holding any locks. */  in seccomp_set_mode_filter()
1974 	prepared = seccomp_prepare_user_filter(filter);  in seccomp_set_mode_filter()
2014 	/* Do not free the successfully attached filter. */  in seccomp_set_mode_filter()
2040 					   const char __user *filter)  in seccomp_set_mode_filter()  argument
2119  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2123 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)  in prctl_set_seccomp()  argument
2132 		 * Setting strict mode through prctl always ignored filter,  in prctl_set_seccomp()
2140 		uargs = filter;  in prctl_set_seccomp()
2154 	struct seccomp_filter *orig, *filter;  in get_nth_filter()  local
2168 	orig = task->seccomp.filter;  in get_nth_filter()
2173 	for (filter = orig; filter; filter = filter->prev)  in get_nth_filter()
2177 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2182 	for (filter = orig; filter && count > 1; filter = filter->prev)  in get_nth_filter()
2185 	if (WARN_ON(count != 1 || !filter)) {  in get_nth_filter()
2186 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2190 	__get_seccomp_filter(filter);  in get_nth_filter()
2194 	return filter;  in get_nth_filter()
2200 	struct seccomp_filter *filter;  in seccomp_get_filter()  local
2209 	filter = get_nth_filter(task, filter_off);  in seccomp_get_filter()
2210 	if (IS_ERR(filter))  in seccomp_get_filter()
2211 		return PTR_ERR(filter);  in seccomp_get_filter()
2213 	fprog = filter->prog->orig_prog;  in seccomp_get_filter()
2215 		/* This must be a new non-cBPF filter, since we save  in seccomp_get_filter()
2216 		 * every cBPF filter's orig_prog above when  in seccomp_get_filter()
2227 	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))  in seccomp_get_filter()
2231 	__put_seccomp_filter(filter);  in seccomp_get_filter()
2239 	struct seccomp_filter *filter;  in seccomp_get_metadata()  local
2255 	filter = get_nth_filter(task, kmd.filter_off);  in seccomp_get_metadata()
2256 	if (IS_ERR(filter))  in seccomp_get_metadata()
2257 		return PTR_ERR(filter);  in seccomp_get_metadata()
2259 	if (filter->log)  in seccomp_get_metadata()
2266 	__put_seccomp_filter(filter);  in seccomp_get_metadata()
2508 		char *status = cached ? "ALLOW" : "FILTER";  in device_initcall()
2530 	f = READ_ONCE(task->seccomp.filter);  in proc_pid_seccomp_cache()
2536 	/* prevent filter from being freed while we are printing it */  in proc_pid_seccomp_cache()