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. */
141  *           filter->notify_lock.
153  * struct action_cache - per-filter cache of seccomp actions per
157  *		  filter will always allow the syscall, for the
160  *		  filter will always allow the syscall, for the
187  *	  A filter's reference count is incremented for each directly
188  *	  attached task, once for the dependent filter, and if
190  *	  the filter can be freed.
191  * @users: A filter's @users count is incremented for each directly
192  *         attached task (filter installation, fork(), thread_sync),
193  *	   and once for the dependent filter (tracked in filter->prev).
195  *	   users of that filter exist. No new tasks can get associated with
196  *	   this filter after reaching 0. The @users count is always smaller
198  *	   the filter can be freed.
201  * @prev: points to a previously installed, or inherited, filter
209  * with current->seccomp.filter, the most recently attached or inherited filter.
259  *	seccomp_check_filter - verify seccomp filter code
260  *	@filter: filter to verify
261  *	@flen: length of filter
263  * Takes a previously checked filter (by bpf_check_classic) and
264  * redirects all filter code that loads struct sk_buff data
270 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)  in seccomp_check_filter()  argument
274 		struct sock_filter *ftest = &filter[pc];  in seccomp_check_filter()
354  * @sfilter: The seccomp filter
390  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
400 	/* Make sure cross-thread synced filter points somewhere sane. */  in seccomp_run_filters()
402 			READ_ONCE(current->seccomp.filter);  in seccomp_run_filters()
448 	 * filter) is set.  in seccomp_assign_mode()
478  * seccomp filter.
498 		     is_ancestor(thread->seccomp.filter,  in seccomp_can_sync_threads()
499 				 caller->seccomp.filter)))  in seccomp_can_sync_threads()
513 static inline void seccomp_filter_free(struct seccomp_filter *filter)  in seccomp_filter_free()  argument
515 	if (filter) {  in seccomp_filter_free()
516 		bpf_prog_destroy(filter->prog);  in seccomp_filter_free()
517 		kfree(filter);  in seccomp_filter_free()
542 	/* Notify about any unused filters in the task's former filter tree. */  in __seccomp_filter_release()
549  * seccomp_filter_release - Detach the task from its filter tree,
554  * it detaches it from its filter tree. As such, READ_ONCE() and
559 	struct seccomp_filter *orig = tsk->seccomp.filter;  in seccomp_filter_release()
564 	/* Detach task from its filter tree. */  in seccomp_filter_release()
565 	tsk->seccomp.filter = NULL;  in seccomp_filter_release()
570  * seccomp_sync_threads: sets all threads to use current's filter
599 		__seccomp_filter_release(thread->seccomp.filter);  in seccomp_sync_threads()
601 		/* Make our new filter tree visible. */  in seccomp_sync_threads()
602 		smp_store_release(&thread->seccomp.filter,  in seccomp_sync_threads()
603 				  caller->seccomp.filter);  in seccomp_sync_threads()
629  * seccomp_prepare_filter: Prepares a seccomp filter for use.
632  * Returns filter on success or an ERR_PTR on failure.
651 	 * Installing a seccomp filter requires that the task has  in seccomp_prepare_filter()
690 	struct seccomp_filter *filter = ERR_PTR(-EFAULT);  in seccomp_prepare_user_filter()  local
698 		fprog.filter = compat_ptr(fprog32.filter);  in seccomp_prepare_user_filter()
703 	filter = seccomp_prepare_filter(&fprog);  in seccomp_prepare_user_filter()
705 	return filter;  in seccomp_prepare_user_filter()
710  * seccomp_is_const_allow - check if filter is constant allow with given data
726 		struct sock_filter *insn = &fprog->filter[pc];  in seccomp_is_const_allow()
783 	/* ran off the end of the filter?! */  in seccomp_is_const_allow()
797 		/* The new filter must be as restrictive as the last. */  in seccomp_cache_prepare_bitmap()
818 		 * atomic clear_bit() not needed, filter not visible yet.  in seccomp_cache_prepare_bitmap()
825  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
826  * @sfilter: The seccomp filter
851  * seccomp_attach_filter: validate and attach filter
852  * @flags:  flags to change filter behavior
853  * @filter: seccomp filter to add to the current process
859  *     seccomp mode or did not have an ancestral seccomp filter
863 				  struct seccomp_filter *filter)  in seccomp_attach_filter()  argument
870 	/* Validate resulting filter length. */  in seccomp_attach_filter()
871 	total_insns = filter->prog->len;  in seccomp_attach_filter()
872 	for (walker = current->seccomp.filter; walker; walker = walker->prev)  in seccomp_attach_filter()
892 		filter->log = true;  in seccomp_attach_filter()
895 	 * If there is an existing filter, make it the prev and don't drop its  in seccomp_attach_filter()
898 	filter->prev = current->seccomp.filter;  in seccomp_attach_filter()
899 	seccomp_cache_prepare(filter);  in seccomp_attach_filter()
900 	current->seccomp.filter = filter;  in seccomp_attach_filter()
903 	/* Now that the new filter is in place, synchronize to all threads. */  in seccomp_attach_filter()
910 static void __get_seccomp_filter(struct seccomp_filter *filter)  in __get_seccomp_filter()  argument
912 	refcount_inc(&filter->refs);  in __get_seccomp_filter()
915 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
918 	struct seccomp_filter *orig = tsk->seccomp.filter;  in get_seccomp_filter()
1036 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)  in seccomp_next_notify_id()  argument
1040 	 * filter.  in seccomp_next_notify_id()
1042 	lockdep_assert_held(&filter->notify_lock);  in seccomp_next_notify_id()
1043 	return filter->notif->next_id++;  in seccomp_next_notify_id()
1196 		/* Let the filter pass back 16 bits of data. */  in __seccomp_filter()
1255 		 * Note that the "match" filter will always be NULL for  in __seccomp_filter()
1353 static void seccomp_notify_free(struct seccomp_filter *filter)  in seccomp_notify_free()  argument
1355 	kfree(filter->notif);  in seccomp_notify_free()
1356 	filter->notif = NULL;  in seccomp_notify_free()
1359 static void seccomp_notify_detach(struct seccomp_filter *filter)  in seccomp_notify_detach()  argument
1363 	if (!filter)  in seccomp_notify_detach()
1366 	mutex_lock(&filter->notify_lock);  in seccomp_notify_detach()
1372 	list_for_each_entry(knotif, &filter->notif->notifications, list) {  in seccomp_notify_detach()
1388 	seccomp_notify_free(filter);  in seccomp_notify_detach()
1389 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_detach()
1394 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_release()  local
1396 	seccomp_notify_detach(filter);  in seccomp_notify_release()
1397 	__put_seccomp_filter(filter);  in seccomp_notify_release()
1403 find_notification(struct seccomp_filter *filter, u64 id)  in find_notification()  argument
1407 	lockdep_assert_held(&filter->notify_lock);  in find_notification()
1409 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in find_notification()
1418 static long seccomp_notify_recv(struct seccomp_filter *filter,  in seccomp_notify_recv()  argument
1434 	ret = down_interruptible(&filter->notif->request);  in seccomp_notify_recv()
1438 	mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1439 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_recv()
1461 	wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);  in seccomp_notify_recv()
1464 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1475 		mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1476 		knotif = find_notification(filter, unotif.id);  in seccomp_notify_recv()
1479 			up(&filter->notif->request);  in seccomp_notify_recv()
1481 		mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1487 static long seccomp_notify_send(struct seccomp_filter *filter,  in seccomp_notify_send()  argument
1504 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_send()
1508 	knotif = find_notification(filter, resp.id);  in seccomp_notify_send()
1527 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_send()
1531 static long seccomp_notify_id_valid(struct seccomp_filter *filter,  in seccomp_notify_id_valid()  argument
1541 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_id_valid()
1545 	knotif = find_notification(filter, id);  in seccomp_notify_id_valid()
1551 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_id_valid()
1555 static long seccomp_notify_addfd(struct seccomp_filter *filter,  in seccomp_notify_addfd()  argument
1593 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_addfd()
1597 	knotif = find_notification(filter, addfd.id);  in seccomp_notify_addfd()
1632 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1648 	mutex_lock(&filter->notify_lock);  in seccomp_notify_addfd()
1662 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1672 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_ioctl()  local
1678 		return seccomp_notify_recv(filter, buf);  in seccomp_notify_ioctl()
1680 		return seccomp_notify_send(filter, buf);  in seccomp_notify_ioctl()
1683 		return seccomp_notify_id_valid(filter, buf);  in seccomp_notify_ioctl()
1690 		return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));  in seccomp_notify_ioctl()
1699 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_poll()  local
1703 	poll_wait(file, &filter->wqh, poll_tab);  in seccomp_notify_poll()
1705 	if (mutex_lock_interruptible(&filter->notify_lock) < 0)  in seccomp_notify_poll()
1708 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_poll()
1717 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_poll()
1719 	if (refcount_read(&filter->users) == 0)  in seccomp_notify_poll()
1732 static struct file *init_listener(struct seccomp_filter *filter)  in init_listener()  argument
1737 	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);  in init_listener()
1738 	if (!filter->notif)  in init_listener()
1741 	sema_init(&filter->notif->request, 0);  in init_listener()
1742 	filter->notif->next_id = get_random_u64();  in init_listener()
1743 	INIT_LIST_HEAD(&filter->notif->notifications);  in init_listener()
1746 				 filter, O_RDWR);  in init_listener()
1751 	__get_seccomp_filter(filter);  in init_listener()
1755 		seccomp_notify_free(filter);  in init_listener()
1762  * If so, we'll want to reject this filter.
1766  * we use current->seccomp.filter.
1777 	for (cur = current->seccomp.filter; cur; cur = cur->prev) {  in has_duplicate_listener()
1786  * seccomp_set_mode_filter: internal function for setting seccomp filter
1787  * @flags:  flags to change filter behavior
1788  * @filter: struct sock_fprog containing filter
1791  * Every filter successfully installed will be evaluated (in reverse order)
1799 				    const char __user *filter)  in seccomp_set_mode_filter()  argument
1823 	/* Prepare the new filter before holding any locks. */  in seccomp_set_mode_filter()
1824 	prepared = seccomp_prepare_user_filter(filter);  in seccomp_set_mode_filter()
1864 	/* Do not free the successfully attached filter. */  in seccomp_set_mode_filter()
1890 					   const char __user *filter)  in seccomp_set_mode_filter()  argument
1969  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1973 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)  in prctl_set_seccomp()  argument
1982 		 * Setting strict mode through prctl always ignored filter,  in prctl_set_seccomp()
1990 		uargs = filter;  in prctl_set_seccomp()
2004 	struct seccomp_filter *orig, *filter;  in get_nth_filter()  local
2018 	orig = task->seccomp.filter;  in get_nth_filter()
2023 	for (filter = orig; filter; filter = filter->prev)  in get_nth_filter()
2027 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2032 	for (filter = orig; filter && count > 1; filter = filter->prev)  in get_nth_filter()
2035 	if (WARN_ON(count != 1 || !filter)) {  in get_nth_filter()
2036 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2040 	__get_seccomp_filter(filter);  in get_nth_filter()
2044 	return filter;  in get_nth_filter()
2050 	struct seccomp_filter *filter;  in seccomp_get_filter()  local
2059 	filter = get_nth_filter(task, filter_off);  in seccomp_get_filter()
2060 	if (IS_ERR(filter))  in seccomp_get_filter()
2061 		return PTR_ERR(filter);  in seccomp_get_filter()
2063 	fprog = filter->prog->orig_prog;  in seccomp_get_filter()
2065 		/* This must be a new non-cBPF filter, since we save  in seccomp_get_filter()
2066 		 * every cBPF filter's orig_prog above when  in seccomp_get_filter()
2077 	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))  in seccomp_get_filter()
2081 	__put_seccomp_filter(filter);  in seccomp_get_filter()
2089 	struct seccomp_filter *filter;  in seccomp_get_metadata()  local
2105 	filter = get_nth_filter(task, kmd.filter_off);  in seccomp_get_metadata()
2106 	if (IS_ERR(filter))  in seccomp_get_metadata()
2107 		return PTR_ERR(filter);  in seccomp_get_metadata()
2109 	if (filter->log)  in seccomp_get_metadata()
2116 	__put_seccomp_filter(filter);  in seccomp_get_metadata()
2372 		char *status = cached ? "ALLOW" : "FILTER";  in device_initcall()
2394 	f = READ_ONCE(task->seccomp.filter);  in proc_pid_seccomp_cache()
2400 	/* prevent filter from being freed while we are printing it */  in proc_pid_seccomp_cache()