41 #include <linux/filter.h>
64 	/* The struct pid of the task whose filter triggered the notification */
67 	/* The "cookie" for this request; this is unique for this filter. */
143  *           filter->notify_lock.
155  * struct action_cache - per-filter cache of seccomp actions per
159  *		  filter will always allow the syscall, for the
162  *		  filter will always allow the syscall, for the
189  *	  A filter's reference count is incremented for each directly
190  *	  attached task, once for the dependent filter, and if
192  *	  the filter can be freed.
193  * @users: A filter's @users count is incremented for each directly
194  *         attached task (filter installation, fork(), thread_sync),
195  *	   and once for the dependent filter (tracked in filter->prev).
197  *	   users of that filter exist. No new tasks can get associated with
198  *	   this filter after reaching 0. The @users count is always smaller
200  *	   the filter can be freed.
205  * @prev: points to a previously installed, or inherited, filter
213  * with current->seccomp.filter, the most recently attached or inherited filter.
264  *	seccomp_check_filter - verify seccomp filter code
265  *	@filter: filter to verify
266  *	@flen: length of filter
268  * Takes a previously checked filter (by bpf_check_classic) and
269  * redirects all filter code that loads struct sk_buff data
275 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)  in seccomp_check_filter()  argument
279 		struct sock_filter *ftest = &filter[pc];  in seccomp_check_filter()
359  * @sfilter: The seccomp filter
395  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
405 	/* Make sure cross-thread synced filter points somewhere sane. */  in seccomp_run_filters()
407 			READ_ONCE(current->seccomp.filter);  in seccomp_run_filters()
453 	 * filter) is set.  in seccomp_assign_mode()
483  * seccomp filter.
503 		     is_ancestor(thread->seccomp.filter,  in seccomp_can_sync_threads()
504 				 caller->seccomp.filter)))  in seccomp_can_sync_threads()
518 static inline void seccomp_filter_free(struct seccomp_filter *filter)  in seccomp_filter_free()  argument
520 	if (filter) {  in seccomp_filter_free()
521 		bpf_prog_destroy(filter->prog);  in seccomp_filter_free()
522 		kfree(filter);  in seccomp_filter_free()
547 	/* Notify about any unused filters in the task's former filter tree. */  in __seccomp_filter_release()
554  * seccomp_filter_release - Detach the task from its filter tree,
559  * it detaches it from its filter tree. As such, READ_ONCE() and
564 	struct seccomp_filter *orig = tsk->seccomp.filter;  in seccomp_filter_release()
569 	/* Detach task from its filter tree. */  in seccomp_filter_release()
570 	tsk->seccomp.filter = NULL;  in seccomp_filter_release()
575  * seccomp_sync_threads: sets all threads to use current's filter
604 		__seccomp_filter_release(thread->seccomp.filter);  in seccomp_sync_threads()
606 		/* Make our new filter tree visible. */  in seccomp_sync_threads()
607 		smp_store_release(&thread->seccomp.filter,  in seccomp_sync_threads()
608 				  caller->seccomp.filter);  in seccomp_sync_threads()
634  * seccomp_prepare_filter: Prepares a seccomp filter for use.
637  * Returns filter on success or an ERR_PTR on failure.
656 	 * Installing a seccomp filter requires that the task has  in seccomp_prepare_filter()
695 	struct seccomp_filter *filter = ERR_PTR(-EFAULT);  in seccomp_prepare_user_filter()  local
703 		fprog.filter = compat_ptr(fprog32.filter);  in seccomp_prepare_user_filter()
708 	filter = seccomp_prepare_filter(&fprog);  in seccomp_prepare_user_filter()
710 	return filter;  in seccomp_prepare_user_filter()
715  * seccomp_is_const_allow - check if filter is constant allow with given data
731 		struct sock_filter *insn = &fprog->filter[pc];  in seccomp_is_const_allow()
788 	/* ran off the end of the filter?! */  in seccomp_is_const_allow()
802 		/* The new filter must be as restrictive as the last. */  in seccomp_cache_prepare_bitmap()
823 		 * atomic clear_bit() not needed, filter not visible yet.  in seccomp_cache_prepare_bitmap()
830  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
831  * @sfilter: The seccomp filter
856  * seccomp_attach_filter: validate and attach filter
857  * @flags:  flags to change filter behavior
858  * @filter: seccomp filter to add to the current process
864  *     seccomp mode or did not have an ancestral seccomp filter
868 				  struct seccomp_filter *filter)  in seccomp_attach_filter()  argument
875 	/* Validate resulting filter length. */  in seccomp_attach_filter()
876 	total_insns = filter->prog->len;  in seccomp_attach_filter()
877 	for (walker = current->seccomp.filter; walker; walker = walker->prev)  in seccomp_attach_filter()
897 		filter->log = true;  in seccomp_attach_filter()
901 		filter->wait_killable_recv = true;  in seccomp_attach_filter()
904 	 * If there is an existing filter, make it the prev and don't drop its  in seccomp_attach_filter()
907 	filter->prev = current->seccomp.filter;  in seccomp_attach_filter()
908 	seccomp_cache_prepare(filter);  in seccomp_attach_filter()
909 	current->seccomp.filter = filter;  in seccomp_attach_filter()
912 	/* Now that the new filter is in place, synchronize to all threads. */  in seccomp_attach_filter()
919 static void __get_seccomp_filter(struct seccomp_filter *filter)  in __get_seccomp_filter()  argument
921 	refcount_inc(&filter->refs);  in __get_seccomp_filter()
924 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
927 	struct seccomp_filter *orig = tsk->seccomp.filter;  in get_seccomp_filter()
1046 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)  in seccomp_next_notify_id()  argument
1050 	 * filter.  in seccomp_next_notify_id()
1052 	lockdep_assert_held(&filter->notify_lock);  in seccomp_next_notify_id()
1053 	return filter->notif->next_id++;  in seccomp_next_notify_id()
1226 		/* Let the filter pass back 16 bits of data. */  in __seccomp_filter()
1285 		 * Note that the "match" filter will always be NULL for  in __seccomp_filter()
1389 static void seccomp_notify_free(struct seccomp_filter *filter)  in seccomp_notify_free()  argument
1391 	kfree(filter->notif);  in seccomp_notify_free()
1392 	filter->notif = NULL;  in seccomp_notify_free()
1395 static void seccomp_notify_detach(struct seccomp_filter *filter)  in seccomp_notify_detach()  argument
1399 	if (!filter)  in seccomp_notify_detach()
1402 	mutex_lock(&filter->notify_lock);  in seccomp_notify_detach()
1408 	list_for_each_entry(knotif, &filter->notif->notifications, list) {  in seccomp_notify_detach()
1424 	seccomp_notify_free(filter);  in seccomp_notify_detach()
1425 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_detach()
1430 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_release()  local
1432 	seccomp_notify_detach(filter);  in seccomp_notify_release()
1433 	__put_seccomp_filter(filter);  in seccomp_notify_release()
1439 find_notification(struct seccomp_filter *filter, u64 id)  in find_notification()  argument
1443 	lockdep_assert_held(&filter->notify_lock);  in find_notification()
1445 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in find_notification()
1454 static long seccomp_notify_recv(struct seccomp_filter *filter,  in seccomp_notify_recv()  argument
1470 	ret = down_interruptible(&filter->notif->request);  in seccomp_notify_recv()
1474 	mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1475 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_recv()
1497 	wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);  in seccomp_notify_recv()
1500 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1511 		mutex_lock(&filter->notify_lock);  in seccomp_notify_recv()
1512 		knotif = find_notification(filter, unotif.id);  in seccomp_notify_recv()
1515 			if (should_sleep_killable(filter, knotif))  in seccomp_notify_recv()
1518 			up(&filter->notif->request);  in seccomp_notify_recv()
1520 		mutex_unlock(&filter->notify_lock);  in seccomp_notify_recv()
1526 static long seccomp_notify_send(struct seccomp_filter *filter,  in seccomp_notify_send()  argument
1543 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_send()
1547 	knotif = find_notification(filter, resp.id);  in seccomp_notify_send()
1566 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_send()
1570 static long seccomp_notify_id_valid(struct seccomp_filter *filter,  in seccomp_notify_id_valid()  argument
1580 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_id_valid()
1584 	knotif = find_notification(filter, id);  in seccomp_notify_id_valid()
1590 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_id_valid()
1594 static long seccomp_notify_addfd(struct seccomp_filter *filter,  in seccomp_notify_addfd()  argument
1632 	ret = mutex_lock_interruptible(&filter->notify_lock);  in seccomp_notify_addfd()
1636 	knotif = find_notification(filter, addfd.id);  in seccomp_notify_addfd()
1671 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1687 	mutex_lock(&filter->notify_lock);  in seccomp_notify_addfd()
1701 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_addfd()
1711 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_ioctl()  local
1717 		return seccomp_notify_recv(filter, buf);  in seccomp_notify_ioctl()
1719 		return seccomp_notify_send(filter, buf);  in seccomp_notify_ioctl()
1722 		return seccomp_notify_id_valid(filter, buf);  in seccomp_notify_ioctl()
1729 		return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));  in seccomp_notify_ioctl()
1738 	struct seccomp_filter *filter = file->private_data;  in seccomp_notify_poll()  local
1742 	poll_wait(file, &filter->wqh, poll_tab);  in seccomp_notify_poll()
1744 	if (mutex_lock_interruptible(&filter->notify_lock) < 0)  in seccomp_notify_poll()
1747 	list_for_each_entry(cur, &filter->notif->notifications, list) {  in seccomp_notify_poll()
1756 	mutex_unlock(&filter->notify_lock);  in seccomp_notify_poll()
1758 	if (refcount_read(&filter->users) == 0)  in seccomp_notify_poll()
1771 static struct file *init_listener(struct seccomp_filter *filter)  in init_listener()  argument
1776 	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);  in init_listener()
1777 	if (!filter->notif)  in init_listener()
1780 	sema_init(&filter->notif->request, 0);  in init_listener()
1781 	filter->notif->next_id = get_random_u64();  in init_listener()
1782 	INIT_LIST_HEAD(&filter->notif->notifications);  in init_listener()
1785 				 filter, O_RDWR);  in init_listener()
1790 	__get_seccomp_filter(filter);  in init_listener()
1794 		seccomp_notify_free(filter);  in init_listener()
1801  * If so, we'll want to reject this filter.
1805  * we use current->seccomp.filter.
1816 	for (cur = current->seccomp.filter; cur; cur = cur->prev) {  in has_duplicate_listener()
1825  * seccomp_set_mode_filter: internal function for setting seccomp filter
1826  * @flags:  flags to change filter behavior
1827  * @filter: struct sock_fprog containing filter
1830  * Every filter successfully installed will be evaluated (in reverse order)
1838 				    const char __user *filter)  in seccomp_set_mode_filter()  argument
1870 	/* Prepare the new filter before holding any locks. */  in seccomp_set_mode_filter()
1871 	prepared = seccomp_prepare_user_filter(filter);  in seccomp_set_mode_filter()
1911 	/* Do not free the successfully attached filter. */  in seccomp_set_mode_filter()
1937 					   const char __user *filter)  in seccomp_set_mode_filter()  argument
2016  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2020 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)  in prctl_set_seccomp()  argument
2029 		 * Setting strict mode through prctl always ignored filter,  in prctl_set_seccomp()
2037 		uargs = filter;  in prctl_set_seccomp()
2051 	struct seccomp_filter *orig, *filter;  in get_nth_filter()  local
2065 	orig = task->seccomp.filter;  in get_nth_filter()
2070 	for (filter = orig; filter; filter = filter->prev)  in get_nth_filter()
2074 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2079 	for (filter = orig; filter && count > 1; filter = filter->prev)  in get_nth_filter()
2082 	if (WARN_ON(count != 1 || !filter)) {  in get_nth_filter()
2083 		filter = ERR_PTR(-ENOENT);  in get_nth_filter()
2087 	__get_seccomp_filter(filter);  in get_nth_filter()
2091 	return filter;  in get_nth_filter()
2097 	struct seccomp_filter *filter;  in seccomp_get_filter()  local
2106 	filter = get_nth_filter(task, filter_off);  in seccomp_get_filter()
2107 	if (IS_ERR(filter))  in seccomp_get_filter()
2108 		return PTR_ERR(filter);  in seccomp_get_filter()
2110 	fprog = filter->prog->orig_prog;  in seccomp_get_filter()
2112 		/* This must be a new non-cBPF filter, since we save  in seccomp_get_filter()
2113 		 * every cBPF filter's orig_prog above when  in seccomp_get_filter()
2124 	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))  in seccomp_get_filter()
2128 	__put_seccomp_filter(filter);  in seccomp_get_filter()
2136 	struct seccomp_filter *filter;  in seccomp_get_metadata()  local
2152 	filter = get_nth_filter(task, kmd.filter_off);  in seccomp_get_metadata()
2153 	if (IS_ERR(filter))  in seccomp_get_metadata()
2154 		return PTR_ERR(filter);  in seccomp_get_metadata()
2156 	if (filter->log)  in seccomp_get_metadata()
2163 	__put_seccomp_filter(filter);  in seccomp_get_metadata()
2419 		char *status = cached ? "ALLOW" : "FILTER";  in device_initcall()
2441 	f = READ_ONCE(task->seccomp.filter);  in proc_pid_seccomp_cache()
2447 	/* prevent filter from being freed while we are printing it */  in proc_pid_seccomp_cache()