linux - kernel/seccomp.c

2569 lines · 65.9 KiB

1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* linux/kernel/seccomp.c
4	*
5	* Copyright 2004-2005 Andrea Arcangeli <[email protected]>
6	*
7	* Copyright (C) 2012 Google, Inc.
8	* Will Drewry <[email protected]>
9	*
10	* This defines a simple but solid secure-computing facility.
11	*
12	* Mode 1 uses a fixed list of allowed system calls.
13	* Mode 2 allows user-defined system call filters in the form
14	* of Berkeley Packet Filters/Linux Socket Filters.
15	*/
16	#define pr_fmt(fmt) "seccomp: " fmt
17
18	#include <linux/refcount.h>
19	#include <linux/audit.h>
20	#include <linux/compat.h>
21	#include <linux/coredump.h>
22	#include <linux/kmemleak.h>
23	#include <linux/nospec.h>
24	#include <linux/prctl.h>
25	#include <linux/sched.h>
26	#include <linux/sched/task_stack.h>
27	#include <linux/seccomp.h>
28	#include <linux/slab.h>
29	#include <linux/syscalls.h>
30	#include <linux/sysctl.h>
31
32	#include <asm/syscall.h>
33
34	/* Not exposed in headers: strictly internal use only. */
35	#define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
36
37	#ifdef CONFIG_SECCOMP_FILTER
38	#include <linux/file.h>
39	#include <linux/filter.h>
40	#include <linux/pid.h>
41	#include <linux/ptrace.h>
42	#include <linux/capability.h>
43	#include <linux/uaccess.h>
44	#include <linux/anon_inodes.h>
45	#include <linux/lockdep.h>
46
47	/*
48	* When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
49	* wrong direction flag in the ioctl number. This is the broken one,
50	* which the kernel needs to keep supporting until all userspaces stop
51	* using the wrong command number.
52	*/
53	#define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
54
55	enum notify_state {
56	SECCOMP_NOTIFY_INIT,
57	SECCOMP_NOTIFY_SENT,
58	SECCOMP_NOTIFY_REPLIED,
59	};
60
61	struct seccomp_knotif {
62	/* The struct pid of the task whose filter triggered the notification */
63	struct task_struct *task;
64
65	/* The "cookie" for this request; this is unique for this filter. */
66	u64 id;
67
68	/*
69	* The seccomp data. This pointer is valid the entire time this
70	* notification is active, since it comes from __seccomp_filter which
71	* eclipses the entire lifecycle here.
72	*/
73	const struct seccomp_data *data;
74
75	/*
76	* Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
77	* struct seccomp_knotif is created and starts out in INIT. Once the
78	* handler reads the notification off of an FD, it transitions to SENT.
79	* If a signal is received the state transitions back to INIT and
80	* another message is sent. When the userspace handler replies, state
81	* transitions to REPLIED.
82	*/
83	enum notify_state state;
84
85	/* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
86	int error;
87	long val;
88	u32 flags;
89
90	/*
91	* Signals when this has changed states, such as the listener
92	* dying, a new seccomp addfd message, or changing to REPLIED
93	*/
94	struct completion ready;
95
96	struct list_head list;
97
98	/* outstanding addfd requests */
99	struct list_head addfd;
100	};
101
102	/**
103	* struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
104	*
105	* @file: A reference to the file to install in the other task
106	* @fd: The fd number to install it at. If the fd number is -1, it means the
107	* installing process should allocate the fd as normal.
108	* @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
109	* is allowed.
110	* @ioctl_flags: The flags used for the seccomp_addfd ioctl.
111	* @setfd: whether or not SECCOMP_ADDFD_FLAG_SETFD was set during notify_addfd
112	* @ret: The return value of the installing process. It is set to the fd num
113	* upon success (>= 0).
114	* @completion: Indicates that the installing process has completed fd
115	* installation, or gone away (either due to successful
116	* reply, or signal)
117	* @list: list_head for chaining seccomp_kaddfd together.
118	*
119	*/
120	struct seccomp_kaddfd {
121	struct file *file;
122	int fd;
123	unsigned int flags;
124	__u32 ioctl_flags;
125
126	union {
127	bool setfd;
128	/* To only be set on reply */
129	int ret;
130	};
131	struct completion completion;
132	struct list_head list;
133	};
134
135	/**
136	* struct notification - container for seccomp userspace notifications. Since
137	* most seccomp filters will not have notification listeners attached and this
138	* structure is fairly large, we store the notification-specific stuff in a
139	* separate structure.
140	*
141	* @requests: A semaphore that users of this notification can wait on for
142	* changes. Actual reads and writes are still controlled with
143	* filter->notify_lock.
144	* @flags: A set of SECCOMP_USER_NOTIF_FD_* flags.
145	* @next_id: The id of the next request.
146	* @notifications: A list of struct seccomp_knotif elements.
147	*/
148
149	struct notification {
150	atomic_t requests;
151	u32 flags;
152	u64 next_id;
153	struct list_head notifications;
154	};
155
156	#ifdef SECCOMP_ARCH_NATIVE
157	/**
158	* struct action_cache - per-filter cache of seccomp actions per
159	* arch/syscall pair
160	*
161	* @allow_native: A bitmap where each bit represents whether the
162	* filter will always allow the syscall, for the
163	* native architecture.
164	* @allow_compat: A bitmap where each bit represents whether the
165	* filter will always allow the syscall, for the
166	* compat architecture.
167	*/
168	struct action_cache {
169	DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
170	#ifdef SECCOMP_ARCH_COMPAT
171	DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
172	#endif
173	};
174	#else
175	struct action_cache { };
176
177	static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
178	const struct seccomp_data *sd)
179	{
180	return false;
181	}
182
183	static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
184	{
185	}
186	#endif /* SECCOMP_ARCH_NATIVE */
187
188	/**
189	* struct seccomp_filter - container for seccomp BPF programs
190	*
191	* @refs: Reference count to manage the object lifetime.
192	* A filter's reference count is incremented for each directly
193	* attached task, once for the dependent filter, and if
194	* requested for the user notifier. When @refs reaches zero,
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).
199	* When it reaches zero it indicates that no direct or indirect
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
202	* or equal to @refs. Hence, reaching 0 for @users does not mean
203	* the filter can be freed.
204	* @cache: cache of arch/syscall mappings to actions
205	* @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
206	* @wait_killable_recv: Put notifying process in killable state once the
207	* notification is received by the userspace listener.
208	* @prev: points to a previously installed, or inherited, filter
209	* @prog: the BPF program to evaluate
210	* @notif: the struct that holds all notification related information
211	* @notify_lock: A lock for all notification-related accesses.
212	* @wqh: A wait queue for poll if a notifier is in use.
213	*
214	* seccomp_filter objects are organized in a tree linked via the @prev
215	* pointer. For any task, it appears to be a singly-linked list starting
216	* with current->seccomp.filter, the most recently attached or inherited filter.
217	* However, multiple filters may share a @prev node, by way of fork(), which
218	* results in a unidirectional tree existing in memory. This is similar to
219	* how namespaces work.
220	*
221	* seccomp_filter objects should never be modified after being attached
222	* to a task_struct (other than @refs).
223	*/
224	struct seccomp_filter {
225	refcount_t refs;
226	refcount_t users;
227	bool log;
228	bool wait_killable_recv;
229	struct action_cache cache;
230	struct seccomp_filter *prev;
231	struct bpf_prog *prog;
232	struct notification *notif;
233	struct mutex notify_lock;
234	wait_queue_head_t wqh;
235	};
236
237	/* Limit any path through the tree to 256KB worth of instructions. */
238	#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
239
240	/*
241	* Endianness is explicitly ignored and left for BPF program authors to manage
242	* as per the specific architecture.
243	*/
244	static void populate_seccomp_data(struct seccomp_data *sd)
245	{
246	/*
247	* Instead of using current_pt_reg(), we're already doing the work
248	* to safely fetch "current", so just use "task" everywhere below.
249	*/
250	struct task_struct *task = current;
251	struct pt_regs *regs = task_pt_regs(task);
252	unsigned long args[6];
253
254	sd->nr = syscall_get_nr(task, regs);
255	sd->arch = syscall_get_arch(task);
256	syscall_get_arguments(task, regs, args);
257	sd->args[0] = args[0];
258	sd->args[1] = args[1];
259	sd->args[2] = args[2];
260	sd->args[3] = args[3];
261	sd->args[4] = args[4];
262	sd->args[5] = args[5];
263	sd->instruction_pointer = KSTK_EIP(task);
264	}
265
266	/**
267	* seccomp_check_filter - verify seccomp filter code
268	* @filter: filter to verify
269	* @flen: length of filter
270	*
271	* Takes a previously checked filter (by bpf_check_classic) and
272	* redirects all filter code that loads struct sk_buff data
273	* and related data through seccomp_bpf_load. It also
274	* enforces length and alignment checking of those loads.
275	*
276	* Returns 0 if the rule set is legal or -EINVAL if not.
277	*/
278	static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
279	{
280	int pc;
281	for (pc = 0; pc < flen; pc++) {
282	struct sock_filter *ftest = &filter[pc];
283	u16 code = ftest->code;
284	u32 k = ftest->k;
285
286	switch (code) {
287	case BPF_LD \| BPF_W \| BPF_ABS:
288	ftest->code = BPF_LDX \| BPF_W \| BPF_ABS;
289	/* 32-bit aligned and not out of bounds. */
290	if (k >= sizeof(struct seccomp_data) \|\| k & 3)
291	return -EINVAL;
292	continue;
293	case BPF_LD \| BPF_W \| BPF_LEN:
294	ftest->code = BPF_LD \| BPF_IMM;
295	ftest->k = sizeof(struct seccomp_data);
296	continue;
297	case BPF_LDX \| BPF_W \| BPF_LEN:
298	ftest->code = BPF_LDX \| BPF_IMM;
299	ftest->k = sizeof(struct seccomp_data);
300	continue;
301	/* Explicitly include allowed calls. */
302	case BPF_RET \| BPF_K:
303	case BPF_RET \| BPF_A:
304	case BPF_ALU \| BPF_ADD \| BPF_K:
305	case BPF_ALU \| BPF_ADD \| BPF_X:
306	case BPF_ALU \| BPF_SUB \| BPF_K:
307	case BPF_ALU \| BPF_SUB \| BPF_X:
308	case BPF_ALU \| BPF_MUL \| BPF_K:
309	case BPF_ALU \| BPF_MUL \| BPF_X:
310	case BPF_ALU \| BPF_DIV \| BPF_K:
311	case BPF_ALU \| BPF_DIV \| BPF_X:
312	case BPF_ALU \| BPF_AND \| BPF_K:
313	case BPF_ALU \| BPF_AND \| BPF_X:
314	case BPF_ALU \| BPF_OR \| BPF_K:
315	case BPF_ALU \| BPF_OR \| BPF_X:
316	case BPF_ALU \| BPF_XOR \| BPF_K:
317	case BPF_ALU \| BPF_XOR \| BPF_X:
318	case BPF_ALU \| BPF_LSH \| BPF_K:
319	case BPF_ALU \| BPF_LSH \| BPF_X:
320	case BPF_ALU \| BPF_RSH \| BPF_K:
321	case BPF_ALU \| BPF_RSH \| BPF_X:
322	case BPF_ALU \| BPF_NEG:
323	case BPF_LD \| BPF_IMM:
324	case BPF_LDX \| BPF_IMM:
325	case BPF_MISC \| BPF_TAX:
326	case BPF_MISC \| BPF_TXA:
327	case BPF_LD \| BPF_MEM:
328	case BPF_LDX \| BPF_MEM:
329	case BPF_ST:
330	case BPF_STX:
331	case BPF_JMP \| BPF_JA:
332	case BPF_JMP \| BPF_JEQ \| BPF_K:
333	case BPF_JMP \| BPF_JEQ \| BPF_X:
334	case BPF_JMP \| BPF_JGE \| BPF_K:
335	case BPF_JMP \| BPF_JGE \| BPF_X:
336	case BPF_JMP \| BPF_JGT \| BPF_K:
337	case BPF_JMP \| BPF_JGT \| BPF_X:
338	case BPF_JMP \| BPF_JSET \| BPF_K:
339	case BPF_JMP \| BPF_JSET \| BPF_X:
340	continue;
341	default:
342	return -EINVAL;
343	}
344	}
345	return 0;
346	}
347
348	#ifdef SECCOMP_ARCH_NATIVE
349	static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
350	size_t bitmap_size,
351	int syscall_nr)
352	{
353	if (unlikely(syscall_nr < 0 \|\| syscall_nr >= bitmap_size))
354	return false;
355	syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
356
357	return test_bit(syscall_nr, bitmap);
358	}
359
360	/**
361	* seccomp_cache_check_allow - lookup seccomp cache
362	* @sfilter: The seccomp filter
363	* @sd: The seccomp data to lookup the cache with
364	*
365	* Returns true if the seccomp_data is cached and allowed.
366	*/
367	static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
368	const struct seccomp_data *sd)
369	{
370	int syscall_nr = sd->nr;
371	const struct action_cache *cache = &sfilter->cache;
372
373	#ifndef SECCOMP_ARCH_COMPAT
374	/* A native-only architecture doesn't need to check sd->arch. */
375	return seccomp_cache_check_allow_bitmap(cache->allow_native,
376	SECCOMP_ARCH_NATIVE_NR,
377	syscall_nr);
378	#else
379	if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
380	return seccomp_cache_check_allow_bitmap(cache->allow_native,
381	SECCOMP_ARCH_NATIVE_NR,
382	syscall_nr);
383	if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
384	return seccomp_cache_check_allow_bitmap(cache->allow_compat,
385	SECCOMP_ARCH_COMPAT_NR,
386	syscall_nr);
387	#endif /* SECCOMP_ARCH_COMPAT */
388
389	WARN_ON_ONCE(true);
390	return false;
391	}
392	#endif /* SECCOMP_ARCH_NATIVE */
393
394	#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
395	/**
396	* seccomp_run_filters - evaluates all seccomp filters against @sd
397	* @sd: optional seccomp data to be passed to filters
398	* @match: stores struct seccomp_filter that resulted in the return value,
399	* unless filter returned SECCOMP_RET_ALLOW, in which case it will
400	* be unchanged.
401	*
402	* Returns valid seccomp BPF response codes.
403	*/
404	static u32 seccomp_run_filters(const struct seccomp_data *sd,
405	struct seccomp_filter **match)
406	{
407	u32 ret = SECCOMP_RET_ALLOW;
408	/* Make sure cross-thread synced filter points somewhere sane. */
409	struct seccomp_filter *f =
410	READ_ONCE(current->seccomp.filter);
411
412	/* Ensure unexpected behavior doesn't result in failing open. */
413	if (WARN_ON(f == NULL))
414	return SECCOMP_RET_KILL_PROCESS;
415
416	if (seccomp_cache_check_allow(f, sd))
417	return SECCOMP_RET_ALLOW;
418
419	/*
420	* All filters in the list are evaluated and the lowest BPF return
421	* value always takes priority (ignoring the DATA).
422	*/
423	for (; f; f = f->prev) {
424	u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
425
426	if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
427	ret = cur_ret;
428	*match = f;
429	}
430	}
431	return ret;
432	}
433	#endif /* CONFIG_SECCOMP_FILTER */
434
435	static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
436	{
437	assert_spin_locked(&current->sighand->siglock);
438
439	if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
440	return false;
441
442	return true;
443	}
444
445	void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
446
447	static inline void seccomp_assign_mode(struct task_struct *task,
448	unsigned long seccomp_mode,
449	unsigned long flags)
450	{
451	assert_spin_locked(&task->sighand->siglock);
452
453	task->seccomp.mode = seccomp_mode;
454	/*
455	* Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
456	* filter) is set.
457	*/
458	smp_mb__before_atomic();
459	/* Assume default seccomp processes want spec flaw mitigation. */
460	if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
461	arch_seccomp_spec_mitigate(task);
462	set_task_syscall_work(task, SECCOMP);
463	}
464
465	#ifdef CONFIG_SECCOMP_FILTER
466	/* Returns 1 if the parent is an ancestor of the child. */
467	static int is_ancestor(struct seccomp_filter *parent,
468	struct seccomp_filter *child)
469	{
470	/* NULL is the root ancestor. */
471	if (parent == NULL)
472	return 1;
473	for (; child; child = child->prev)
474	if (child == parent)
475	return 1;
476	return 0;
477	}
478
479	/**
480	* seccomp_can_sync_threads: checks if all threads can be synchronized
481	*
482	* Expects sighand and cred_guard_mutex locks to be held.
483	*
484	* Returns 0 on success, -ve on error, or the pid of a thread which was
485	* either not in the correct seccomp mode or did not have an ancestral
486	* seccomp filter.
487	*/
488	static inline pid_t seccomp_can_sync_threads(void)
489	{
490	struct task_struct thread, caller;
491
492	BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
493	assert_spin_locked(&current->sighand->siglock);
494
495	/* Validate all threads being eligible for synchronization. */
496	caller = current;
497	for_each_thread(caller, thread) {
498	pid_t failed;
499
500	/* Skip current, since it is initiating the sync. */
501	if (thread == caller)
502	continue;
503	/* Skip exited threads. */
504	if (thread->flags & PF_EXITING)
505	continue;
506
507	if (thread->seccomp.mode == SECCOMP_MODE_DISABLED \|\|
508	(thread->seccomp.mode == SECCOMP_MODE_FILTER &&
509	is_ancestor(thread->seccomp.filter,
510	caller->seccomp.filter)))
511	continue;
512
513	/* Return the first thread that cannot be synchronized. */
514	failed = task_pid_vnr(thread);
515	/* If the pid cannot be resolved, then return -ESRCH */
516	if (WARN_ON(failed == 0))
517	failed = -ESRCH;
518	return failed;
519	}
520
521	return 0;
522	}
523
524	static inline void seccomp_filter_free(struct seccomp_filter *filter)
525	{
526	if (filter) {
527	bpf_prog_destroy(filter->prog);
528	kfree(filter);
529	}
530	}
531
532	static void __seccomp_filter_orphan(struct seccomp_filter *orig)
533	{
534	while (orig && refcount_dec_and_test(&orig->users)) {
535	if (waitqueue_active(&orig->wqh))
536	wake_up_poll(&orig->wqh, EPOLLHUP);
537	orig = orig->prev;
538	}
539	}
540
541	static void __put_seccomp_filter(struct seccomp_filter *orig)
542	{
543	/* Clean up single-reference branches iteratively. */
544	while (orig && refcount_dec_and_test(&orig->refs)) {
545	struct seccomp_filter *freeme = orig;
546	orig = orig->prev;
547	seccomp_filter_free(freeme);
548	}
549	}
550
551	static void __seccomp_filter_release(struct seccomp_filter *orig)
552	{
553	/* Notify about any unused filters in the task's former filter tree. */
554	__seccomp_filter_orphan(orig);
555	/* Finally drop all references to the task's former tree. */
556	__put_seccomp_filter(orig);
557	}
558
559	/**
560	* seccomp_filter_release - Detach the task from its filter tree,
561	* drop its reference count, and notify
562	* about unused filters
563	*
564	* @tsk: task the filter should be released from.
565	*
566	* This function should only be called when the task is exiting as
567	* it detaches it from its filter tree. PF_EXITING has to be set
568	* for the task.
569	*/
570	void seccomp_filter_release(struct task_struct *tsk)
571	{
572	struct seccomp_filter *orig;
573
574	if (WARN_ON((tsk->flags & PF_EXITING) == 0))
575	return;
576
577	if (READ_ONCE(tsk->seccomp.filter) == NULL)
578	return;
579
580	spin_lock_irq(&tsk->sighand->siglock);
581	orig = tsk->seccomp.filter;
582	/* Detach task from its filter tree. */
583	tsk->seccomp.filter = NULL;
584	spin_unlock_irq(&tsk->sighand->siglock);
585	__seccomp_filter_release(orig);
586	}
587
588	/**
589	* seccomp_sync_threads: sets all threads to use current's filter
590	*
591	* @flags: SECCOMP_FILTER_FLAG_* flags to set during sync.
592	*
593	* Expects sighand and cred_guard_mutex locks to be held, and for
594	* seccomp_can_sync_threads() to have returned success already
595	* without dropping the locks.
596	*
597	*/
598	static inline void seccomp_sync_threads(unsigned long flags)
599	{
600	struct task_struct thread, caller;
601
602	BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
603	assert_spin_locked(&current->sighand->siglock);
604
605	/*
606	* Don't touch any of the threads if the process is being killed.
607	* This allows for a lockless check in seccomp_filter_release.
608	*/
609	if (current->signal->flags & SIGNAL_GROUP_EXIT)
610	return;
611
612	/* Synchronize all threads. */
613	caller = current;
614	for_each_thread(caller, thread) {
615	/* Skip current, since it needs no changes. */
616	if (thread == caller)
617	continue;
618
619	/*
620	* Skip exited threads. seccomp_filter_release could have
621	* been already called for this task.
622	*/
623	if (thread->flags & PF_EXITING)
624	continue;
625
626	/* Get a task reference for the new leaf node. */
627	get_seccomp_filter(caller);
628
629	/*
630	* Drop the task reference to the shared ancestor since
631	* current's path will hold a reference. (This also
632	* allows a put before the assignment.)
633	*/
634	__seccomp_filter_release(thread->seccomp.filter);
635
636	/* Make our new filter tree visible. */
637	smp_store_release(&thread->seccomp.filter,
638	caller->seccomp.filter);
639	atomic_set(&thread->seccomp.filter_count,
640	atomic_read(&caller->seccomp.filter_count));
641
642	/*
643	* Don't let an unprivileged task work around
644	* the no_new_privs restriction by creating
645	* a thread that sets it up, enters seccomp,
646	* then dies.
647	*/
648	if (task_no_new_privs(caller))
649	task_set_no_new_privs(thread);
650
651	/*
652	* Opt the other thread into seccomp if needed.
653	* As threads are considered to be trust-realm
654	* equivalent (see ptrace_may_access), it is safe to
655	* allow one thread to transition the other.
656	*/
657	if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
658	seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
659	flags);
660	}
661	}
662
663	/**
664	* seccomp_prepare_filter: Prepares a seccomp filter for use.
665	* @fprog: BPF program to install
666	*
667	* Returns filter on success or an ERR_PTR on failure.
668	*/
669	static struct seccomp_filter seccomp_prepare_filter(struct sock_fprog fprog)
670	{
671	struct seccomp_filter *sfilter;
672	int ret;
673	const bool save_orig =
674	#if defined(CONFIG_CHECKPOINT_RESTORE) \|\| defined(SECCOMP_ARCH_NATIVE)
675	true;
676	#else
677	false;
678	#endif
679
680	if (fprog->len == 0 \|\| fprog->len > BPF_MAXINSNS)
681	return ERR_PTR(-EINVAL);
682
683	BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
684
685	/*
686	* Installing a seccomp filter requires that the task has
687	* CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
688	* This avoids scenarios where unprivileged tasks can affect the
689	* behavior of privileged children.
690	*/
691	if (!task_no_new_privs(current) &&
692	!ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
693	return ERR_PTR(-EACCES);
694
695	/* Allocate a new seccomp_filter */
696	sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL \| __GFP_NOWARN);
697	if (!sfilter)
698	return ERR_PTR(-ENOMEM);
699
700	mutex_init(&sfilter->notify_lock);
701	ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
702	seccomp_check_filter, save_orig);
703	if (ret < 0) {
704	kfree(sfilter);
705	return ERR_PTR(ret);
706	}
707
708	refcount_set(&sfilter->refs, 1);
709	refcount_set(&sfilter->users, 1);
710	init_waitqueue_head(&sfilter->wqh);
711
712	return sfilter;
713	}
714
715	/**
716	* seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
717	* @user_filter: pointer to the user data containing a sock_fprog.
718	*
719	* Returns 0 on success and non-zero otherwise.
720	*/
721	static struct seccomp_filter *
722	seccomp_prepare_user_filter(const char __user *user_filter)
723	{
724	struct sock_fprog fprog;
725	struct seccomp_filter *filter = ERR_PTR(-EFAULT);
726
727	#ifdef CONFIG_COMPAT
728	if (in_compat_syscall()) {
729	struct compat_sock_fprog fprog32;
730	if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
731	goto out;
732	fprog.len = fprog32.len;
733	fprog.filter = compat_ptr(fprog32.filter);
734	} else /* falls through to the if below. */
735	#endif
736	if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
737	goto out;
738	filter = seccomp_prepare_filter(&fprog);
739	out:
740	return filter;
741	}
742
743	#ifdef SECCOMP_ARCH_NATIVE
744	static bool seccomp_uprobe_exception(struct seccomp_data *sd)
745	{
746	#if defined __NR_uretprobe \|\| defined __NR_uprobe
747	#ifdef SECCOMP_ARCH_COMPAT
748	if (sd->arch == SECCOMP_ARCH_NATIVE)
749	#endif
750	{
751	#ifdef __NR_uretprobe
752	if (sd->nr == __NR_uretprobe)
753	return true;
754	#endif
755	#ifdef __NR_uprobe
756	if (sd->nr == __NR_uprobe)
757	return true;
758	#endif
759	}
760	#endif
761	return false;
762	}
763
764	/**
765	* seccomp_is_const_allow - check if filter is constant allow with given data
766	* @fprog: The BPF programs
767	* @sd: The seccomp data to check against, only syscall number and arch
768	* number are considered constant.
769	*/
770	static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
771	struct seccomp_data *sd)
772	{
773	unsigned int reg_value = 0;
774	unsigned int pc;
775	bool op_res;
776
777	if (WARN_ON_ONCE(!fprog))
778	return false;
779
780	/* Our single exception to filtering. */
781	if (seccomp_uprobe_exception(sd))
782	return true;
783
784	for (pc = 0; pc < fprog->len; pc++) {
785	struct sock_filter *insn = &fprog->filter[pc];
786	u16 code = insn->code;
787	u32 k = insn->k;
788
789	switch (code) {
790	case BPF_LD \| BPF_W \| BPF_ABS:
791	switch (k) {
792	case offsetof(struct seccomp_data, nr):
793	reg_value = sd->nr;
794	break;
795	case offsetof(struct seccomp_data, arch):
796	reg_value = sd->arch;
797	break;
798	default:
799	/* can't optimize (non-constant value load) */
800	return false;
801	}
802	break;
803	case BPF_RET \| BPF_K:
804	/* reached return with constant values only, check allow */
805	return k == SECCOMP_RET_ALLOW;
806	case BPF_JMP \| BPF_JA:
807	pc += insn->k;
808	break;
809	case BPF_JMP \| BPF_JEQ \| BPF_K:
810	case BPF_JMP \| BPF_JGE \| BPF_K:
811	case BPF_JMP \| BPF_JGT \| BPF_K:
812	case BPF_JMP \| BPF_JSET \| BPF_K:
813	switch (BPF_OP(code)) {
814	case BPF_JEQ:
815	op_res = reg_value == k;
816	break;
817	case BPF_JGE:
818	op_res = reg_value >= k;
819	break;
820	case BPF_JGT:
821	op_res = reg_value > k;
822	break;
823	case BPF_JSET:
824	op_res = !!(reg_value & k);
825	break;
826	default:
827	/* can't optimize (unknown jump) */
828	return false;
829	}
830
831	pc += op_res ? insn->jt : insn->jf;
832	break;
833	case BPF_ALU \| BPF_AND \| BPF_K:
834	reg_value &= k;
835	break;
836	default:
837	/* can't optimize (unknown insn) */
838	return false;
839	}
840	}
841
842	/* ran off the end of the filter?! */
843	WARN_ON(1);
844	return false;
845	}
846
847	static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
848	void bitmap, const void bitmap_prev,
849	size_t bitmap_size, int arch)
850	{
851	struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
852	struct seccomp_data sd;
853	int nr;
854
855	if (bitmap_prev) {
856	/* The new filter must be as restrictive as the last. */
857	bitmap_copy(bitmap, bitmap_prev, bitmap_size);
858	} else {
859	/* Before any filters, all syscalls are always allowed. */
860	bitmap_fill(bitmap, bitmap_size);
861	}
862
863	for (nr = 0; nr < bitmap_size; nr++) {
864	/* No bitmap change: not a cacheable action. */
865	if (!test_bit(nr, bitmap))
866	continue;
867
868	sd.nr = nr;
869	sd.arch = arch;
870
871	/* No bitmap change: continue to always allow. */
872	if (seccomp_is_const_allow(fprog, &sd))
873	continue;
874
875	/*
876	* Not a cacheable action: always run filters.
877	* atomic clear_bit() not needed, filter not visible yet.
878	*/
879	__clear_bit(nr, bitmap);
880	}
881	}
882
883	/**
884	* seccomp_cache_prepare - emulate the filter to find cacheable syscalls
885	* @sfilter: The seccomp filter
886	*
887	* Returns 0 if successful or -errno if error occurred.
888	*/
889	static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
890	{
891	struct action_cache *cache = &sfilter->cache;
892	const struct action_cache *cache_prev =
893	sfilter->prev ? &sfilter->prev->cache : NULL;
894
895	seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
896	cache_prev ? cache_prev->allow_native : NULL,
897	SECCOMP_ARCH_NATIVE_NR,
898	SECCOMP_ARCH_NATIVE);
899
900	#ifdef SECCOMP_ARCH_COMPAT
901	seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
902	cache_prev ? cache_prev->allow_compat : NULL,
903	SECCOMP_ARCH_COMPAT_NR,
904	SECCOMP_ARCH_COMPAT);
905	#endif /* SECCOMP_ARCH_COMPAT */
906	}
907	#endif /* SECCOMP_ARCH_NATIVE */
908
909	/**
910	* seccomp_attach_filter: validate and attach filter
911	* @flags: flags to change filter behavior
912	* @filter: seccomp filter to add to the current process
913	*
914	* Caller must be holding current->sighand->siglock lock.
915	*
916	* Returns 0 on success, -ve on error, or
917	* - in TSYNC mode: the pid of a thread which was either not in the correct
918	* seccomp mode or did not have an ancestral seccomp filter
919	* - in NEW_LISTENER mode: the fd of the new listener
920	*/
921	static long seccomp_attach_filter(unsigned int flags,
922	struct seccomp_filter *filter)
923	{
924	unsigned long total_insns;
925	struct seccomp_filter *walker;
926
927	assert_spin_locked(&current->sighand->siglock);
928
929	/* Validate resulting filter length. */
930	total_insns = filter->prog->len;
931	for (walker = current->seccomp.filter; walker; walker = walker->prev)
932	total_insns += walker->prog->len + 4; /* 4 instr penalty */
933	if (total_insns > MAX_INSNS_PER_PATH)
934	return -ENOMEM;
935
936	/* If thread sync has been requested, check that it is possible. */
937	if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
938	int ret;
939
940	ret = seccomp_can_sync_threads();
941	if (ret) {
942	if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
943	return -ESRCH;
944	else
945	return ret;
946	}
947	}
948
949	/* Set log flag, if present. */
950	if (flags & SECCOMP_FILTER_FLAG_LOG)
951	filter->log = true;
952
953	/* Set wait killable flag, if present. */
954	if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
955	filter->wait_killable_recv = true;
956
957	/*
958	* If there is an existing filter, make it the prev and don't drop its
959	* task reference.
960	*/
961	filter->prev = current->seccomp.filter;
962	seccomp_cache_prepare(filter);
963	current->seccomp.filter = filter;
964	atomic_inc(&current->seccomp.filter_count);
965
966	/* Now that the new filter is in place, synchronize to all threads. */
967	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
968	seccomp_sync_threads(flags);
969
970	return 0;
971	}
972
973	static void __get_seccomp_filter(struct seccomp_filter *filter)
974	{
975	refcount_inc(&filter->refs);
976	}
977
978	/* get_seccomp_filter - increments the reference count of the filter on @tsk */
979	void get_seccomp_filter(struct task_struct *tsk)
980	{
981	struct seccomp_filter *orig = tsk->seccomp.filter;
982	if (!orig)
983	return;
984	__get_seccomp_filter(orig);
985	refcount_inc(&orig->users);
986	}
987
988	#endif /* CONFIG_SECCOMP_FILTER */
989
990	/* For use with seccomp_actions_logged */
991	#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
992	#define SECCOMP_LOG_KILL_THREAD (1 << 1)
993	#define SECCOMP_LOG_TRAP (1 << 2)
994	#define SECCOMP_LOG_ERRNO (1 << 3)
995	#define SECCOMP_LOG_TRACE (1 << 4)
996	#define SECCOMP_LOG_LOG (1 << 5)
997	#define SECCOMP_LOG_ALLOW (1 << 6)
998	#define SECCOMP_LOG_USER_NOTIF (1 << 7)
999
1000	static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS \|
1001	SECCOMP_LOG_KILL_THREAD \|
1002	SECCOMP_LOG_TRAP \|
1003	SECCOMP_LOG_ERRNO \|
1004	SECCOMP_LOG_USER_NOTIF \|
1005	SECCOMP_LOG_TRACE \|
1006	SECCOMP_LOG_LOG;
1007
1008	static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
1009	bool requested)
1010	{
1011	bool log = false;
1012
1013	switch (action) {
1014	case SECCOMP_RET_ALLOW:
1015	break;
1016	case SECCOMP_RET_TRAP:
1017	log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
1018	break;
1019	case SECCOMP_RET_ERRNO:
1020	log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
1021	break;
1022	case SECCOMP_RET_TRACE:
1023	log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
1024	break;
1025	case SECCOMP_RET_USER_NOTIF:
1026	log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
1027	break;
1028	case SECCOMP_RET_LOG:
1029	log = seccomp_actions_logged & SECCOMP_LOG_LOG;
1030	break;
1031	case SECCOMP_RET_KILL_THREAD:
1032	log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
1033	break;
1034	case SECCOMP_RET_KILL_PROCESS:
1035	default:
1036	log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
1037	}
1038
1039	/*
1040	* Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1041	* FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1042	* any action from being logged by removing the action name from the
1043	* seccomp_actions_logged sysctl.
1044	*/
1045	if (!log)
1046	return;
1047
1048	audit_seccomp(syscall, signr, action);
1049	}
1050
1051	/*
1052	* Secure computing mode 1 allows only read/write/exit/sigreturn.
1053	* To be fully secure this must be combined with rlimit
1054	* to limit the stack allocations too.
1055	*/
1056	static const int mode1_syscalls[] = {
1057	__NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1058	#ifdef __NR_uretprobe
1059	__NR_uretprobe,
1060	#endif
1061	#ifdef __NR_uprobe
1062	__NR_uprobe,
1063	#endif
1064	-1, /* negative terminated */
1065	};
1066
1067	static void __secure_computing_strict(int this_syscall)
1068	{
1069	const int *allowed_syscalls = mode1_syscalls;
1070	#ifdef CONFIG_COMPAT
1071	if (in_compat_syscall())
1072	allowed_syscalls = get_compat_mode1_syscalls();
1073	#endif
1074	do {
1075	if (*allowed_syscalls == this_syscall)
1076	return;
1077	} while (*++allowed_syscalls != -1);
1078
1079	#ifdef SECCOMP_DEBUG
1080	dump_stack();
1081	#endif
1082	current->seccomp.mode = SECCOMP_MODE_DEAD;
1083	seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1084	do_exit(SIGKILL);
1085	}
1086
1087	#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1088	void secure_computing_strict(int this_syscall)
1089	{
1090	int mode = current->seccomp.mode;
1091
1092	if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1093	unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1094	return;
1095
1096	if (mode == SECCOMP_MODE_DISABLED)
1097	return;
1098	else if (mode == SECCOMP_MODE_STRICT)
1099	__secure_computing_strict(this_syscall);
1100	else
1101	BUG();
1102	}
1103	int __secure_computing(void)
1104	{
1105	int this_syscall = syscall_get_nr(current, current_pt_regs());
1106
1107	secure_computing_strict(this_syscall);
1108	return 0;
1109	}
1110	#else
1111
1112	#ifdef CONFIG_SECCOMP_FILTER
1113	static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1114	{
1115	/*
1116	* Note: overflow is ok here, the id just needs to be unique per
1117	* filter.
1118	*/
1119	lockdep_assert_held(&filter->notify_lock);
1120	return filter->notif->next_id++;
1121	}
1122
1123	static void seccomp_handle_addfd(struct seccomp_kaddfd addfd, struct seccomp_knotif n)
1124	{
1125	int fd;
1126
1127	/*
1128	* Remove the notification, and reset the list pointers, indicating
1129	* that it has been handled.
1130	*/
1131	list_del_init(&addfd->list);
1132	if (!addfd->setfd)
1133	fd = receive_fd(addfd->file, NULL, addfd->flags);
1134	else
1135	fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1136	addfd->ret = fd;
1137
1138	if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1139	/* If we fail reset and return an error to the notifier */
1140	if (fd < 0) {
1141	n->state = SECCOMP_NOTIFY_SENT;
1142	} else {
1143	/* Return the FD we just added */
1144	n->flags = 0;
1145	n->error = 0;
1146	n->val = fd;
1147	}
1148	}
1149
1150	/*
1151	* Mark the notification as completed. From this point, addfd mem
1152	* might be invalidated and we can't safely read it anymore.
1153	*/
1154	complete(&addfd->completion);
1155	}
1156
1157	static bool should_sleep_killable(struct seccomp_filter *match,
1158	struct seccomp_knotif *n)
1159	{
1160	return match->wait_killable_recv && n->state >= SECCOMP_NOTIFY_SENT;
1161	}
1162
1163	static int seccomp_do_user_notification(int this_syscall,
1164	struct seccomp_filter *match,
1165	const struct seccomp_data *sd)
1166	{
1167	int err;
1168	u32 flags = 0;
1169	long ret = 0;
1170	struct seccomp_knotif n = {};
1171	struct seccomp_kaddfd addfd, tmp;
1172
1173	mutex_lock(&match->notify_lock);
1174	err = -ENOSYS;
1175	if (!match->notif)
1176	goto out;
1177
1178	n.task = current;
1179	n.state = SECCOMP_NOTIFY_INIT;
1180	n.data = sd;
1181	n.id = seccomp_next_notify_id(match);
1182	init_completion(&n.ready);
1183	list_add_tail(&n.list, &match->notif->notifications);
1184	INIT_LIST_HEAD(&n.addfd);
1185
1186	atomic_inc(&match->notif->requests);
1187	if (match->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1188	wake_up_poll_on_current_cpu(&match->wqh, EPOLLIN \| EPOLLRDNORM);
1189	else
1190	wake_up_poll(&match->wqh, EPOLLIN \| EPOLLRDNORM);
1191
1192	/*
1193	* This is where we wait for a reply from userspace.
1194	*/
1195	do {
1196	bool wait_killable = should_sleep_killable(match, &n);
1197
1198	mutex_unlock(&match->notify_lock);
1199	if (wait_killable)
1200	err = wait_for_completion_killable(&n.ready);
1201	else
1202	err = wait_for_completion_interruptible(&n.ready);
1203	mutex_lock(&match->notify_lock);
1204
1205	if (err != 0) {
1206	/*
1207	* Check to see whether we should switch to wait
1208	* killable. Only return the interrupted error if not.
1209	*/
1210	if (!(!wait_killable && should_sleep_killable(match, &n)))
1211	goto interrupted;
1212	}
1213
1214	addfd = list_first_entry_or_null(&n.addfd,
1215	struct seccomp_kaddfd, list);
1216	/* Check if we were woken up by a addfd message */
1217	if (addfd)
1218	seccomp_handle_addfd(addfd, &n);
1219
1220	} while (n.state != SECCOMP_NOTIFY_REPLIED);
1221
1222	ret = n.val;
1223	err = n.error;
1224	flags = n.flags;
1225
1226	interrupted:
1227	/* If there were any pending addfd calls, clear them out */
1228	list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1229	/* The process went away before we got a chance to handle it */
1230	addfd->ret = -ESRCH;
1231	list_del_init(&addfd->list);
1232	complete(&addfd->completion);
1233	}
1234
1235	/*
1236	* Note that it's possible the listener died in between the time when
1237	* we were notified of a response (or a signal) and when we were able to
1238	* re-acquire the lock, so only delete from the list if the
1239	* notification actually exists.
1240	*
1241	* Also note that this test is only valid because there's no way to
1242	* reattach to a notifier right now. If one is added, we'll need to
1243	* keep track of the notif itself and make sure they match here.
1244	*/
1245	if (match->notif)
1246	list_del(&n.list);
1247	out:
1248	mutex_unlock(&match->notify_lock);
1249
1250	/* Userspace requests to continue the syscall. */
1251	if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1252	return 0;
1253
1254	syscall_set_return_value(current, current_pt_regs(),
1255	err, ret);
1256	return -1;
1257	}
1258
1259	static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
1260	{
1261	u32 filter_ret, action;
1262	struct seccomp_data sd;
1263	struct seccomp_filter *match = NULL;
1264	int data;
1265
1266	/*
1267	* Make sure that any changes to mode from another thread have
1268	* been seen after SYSCALL_WORK_SECCOMP was seen.
1269	*/
1270	smp_rmb();
1271
1272	populate_seccomp_data(&sd);
1273
1274	filter_ret = seccomp_run_filters(&sd, &match);
1275	data = filter_ret & SECCOMP_RET_DATA;
1276	action = filter_ret & SECCOMP_RET_ACTION_FULL;
1277
1278	switch (action) {
1279	case SECCOMP_RET_ERRNO:
1280	/* Set low-order bits as an errno, capped at MAX_ERRNO. */
1281	if (data > MAX_ERRNO)
1282	data = MAX_ERRNO;
1283	syscall_set_return_value(current, current_pt_regs(),
1284	-data, 0);
1285	goto skip;
1286
1287	case SECCOMP_RET_TRAP:
1288	/* Show the handler the original registers. */
1289	syscall_rollback(current, current_pt_regs());
1290	/* Let the filter pass back 16 bits of data. */
1291	force_sig_seccomp(this_syscall, data, false);
1292	goto skip;
1293
1294	case SECCOMP_RET_TRACE:
1295	/* We've been put in this state by the ptracer already. */
1296	if (recheck_after_trace)
1297	return 0;
1298
1299	/* ENOSYS these calls if there is no tracer attached. */
1300	if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1301	syscall_set_return_value(current,
1302	current_pt_regs(),
1303	-ENOSYS, 0);
1304	goto skip;
1305	}
1306
1307	/* Allow the BPF to provide the event message */
1308	ptrace_event(PTRACE_EVENT_SECCOMP, data);
1309	/*
1310	* The delivery of a fatal signal during event
1311	* notification may silently skip tracer notification,
1312	* which could leave us with a potentially unmodified
1313	* syscall that the tracer would have liked to have
1314	* changed. Since the process is about to die, we just
1315	* force the syscall to be skipped and let the signal
1316	* kill the process and correctly handle any tracer exit
1317	* notifications.
1318	*/
1319	if (fatal_signal_pending(current))
1320	goto skip;
1321	/* Check if the tracer forced the syscall to be skipped. */
1322	this_syscall = syscall_get_nr(current, current_pt_regs());
1323	if (this_syscall < 0)
1324	goto skip;
1325
1326	/*
1327	* Recheck the syscall, since it may have changed. This
1328	* intentionally uses a NULL struct seccomp_data to force
1329	* a reload of all registers. This does not goto skip since
1330	* a skip would have already been reported.
1331	*/
1332	if (__seccomp_filter(this_syscall, true))
1333	return -1;
1334
1335	return 0;
1336
1337	case SECCOMP_RET_USER_NOTIF:
1338	if (seccomp_do_user_notification(this_syscall, match, &sd))
1339	goto skip;
1340
1341	return 0;
1342
1343	case SECCOMP_RET_LOG:
1344	seccomp_log(this_syscall, 0, action, true);
1345	return 0;
1346
1347	case SECCOMP_RET_ALLOW:
1348	/*
1349	* Note that the "match" filter will always be NULL for
1350	* this action since SECCOMP_RET_ALLOW is the starting
1351	* state in seccomp_run_filters().
1352	*/
1353	return 0;
1354
1355	case SECCOMP_RET_KILL_THREAD:
1356	case SECCOMP_RET_KILL_PROCESS:
1357	default:
1358	current->seccomp.mode = SECCOMP_MODE_DEAD;
1359	seccomp_log(this_syscall, SIGSYS, action, true);
1360	/* Dump core only if this is the last remaining thread. */
1361	if (action != SECCOMP_RET_KILL_THREAD \|\|
1362	(atomic_read(&current->signal->live) == 1)) {
1363	/* Show the original registers in the dump. */
1364	syscall_rollback(current, current_pt_regs());
1365	/* Trigger a coredump with SIGSYS */
1366	force_sig_seccomp(this_syscall, data, true);
1367	} else {
1368	do_exit(SIGSYS);
1369	}
1370	return -1; /* skip the syscall go directly to signal handling */
1371	}
1372
1373	unreachable();
1374
1375	skip:
1376	seccomp_log(this_syscall, 0, action, match ? match->log : false);
1377	return -1;
1378	}
1379	#else
1380	static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
1381	{
1382	BUG();
1383
1384	return -1;
1385	}
1386	#endif
1387
1388	int __secure_computing(void)
1389	{
1390	int mode = current->seccomp.mode;
1391	int this_syscall;
1392
1393	if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1394	unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1395	return 0;
1396
1397	this_syscall = syscall_get_nr(current, current_pt_regs());
1398
1399	switch (mode) {
1400	case SECCOMP_MODE_STRICT:
1401	__secure_computing_strict(this_syscall); /* may call do_exit */
1402	return 0;
1403	case SECCOMP_MODE_FILTER:
1404	return __seccomp_filter(this_syscall, false);
1405	/* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1406	case SECCOMP_MODE_DEAD:
1407	WARN_ON_ONCE(1);
1408	do_exit(SIGKILL);
1409	return -1;
1410	default:
1411	BUG();
1412	}
1413	}
1414	#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1415
1416	long prctl_get_seccomp(void)
1417	{
1418	return current->seccomp.mode;
1419	}
1420
1421	/**
1422	* seccomp_set_mode_strict: internal function for setting strict seccomp
1423	*
1424	* Once current->seccomp.mode is non-zero, it may not be changed.
1425	*
1426	* Returns 0 on success or -EINVAL on failure.
1427	*/
1428	static long seccomp_set_mode_strict(void)
1429	{
1430	const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1431	long ret = -EINVAL;
1432
1433	spin_lock_irq(&current->sighand->siglock);
1434
1435	if (!seccomp_may_assign_mode(seccomp_mode))
1436	goto out;
1437
1438	#ifdef TIF_NOTSC
1439	disable_TSC();
1440	#endif
1441	seccomp_assign_mode(current, seccomp_mode, 0);
1442	ret = 0;
1443
1444	out:
1445	spin_unlock_irq(&current->sighand->siglock);
1446
1447	return ret;
1448	}
1449
1450	#ifdef CONFIG_SECCOMP_FILTER
1451	static void seccomp_notify_free(struct seccomp_filter *filter)
1452	{
1453	kfree(filter->notif);
1454	filter->notif = NULL;
1455	}
1456
1457	static void seccomp_notify_detach(struct seccomp_filter *filter)
1458	{
1459	struct seccomp_knotif *knotif;
1460
1461	if (!filter)
1462	return;
1463
1464	mutex_lock(&filter->notify_lock);
1465
1466	/*
1467	* If this file is being closed because e.g. the task who owned it
1468	* died, let's wake everyone up who was waiting on us.
1469	*/
1470	list_for_each_entry(knotif, &filter->notif->notifications, list) {
1471	if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1472	continue;
1473
1474	knotif->state = SECCOMP_NOTIFY_REPLIED;
1475	knotif->error = -ENOSYS;
1476	knotif->val = 0;
1477
1478	/*
1479	* We do not need to wake up any pending addfd messages, as
1480	* the notifier will do that for us, as this just looks
1481	* like a standard reply.
1482	*/
1483	complete(&knotif->ready);
1484	}
1485
1486	seccomp_notify_free(filter);
1487	mutex_unlock(&filter->notify_lock);
1488	}
1489
1490	static int seccomp_notify_release(struct inode inode, struct file file)
1491	{
1492	struct seccomp_filter *filter = file->private_data;
1493
1494	seccomp_notify_detach(filter);
1495	__put_seccomp_filter(filter);
1496	return 0;
1497	}
1498
1499	/* must be called with notif_lock held */
1500	static inline struct seccomp_knotif *
1501	find_notification(struct seccomp_filter *filter, u64 id)
1502	{
1503	struct seccomp_knotif *cur;
1504
1505	lockdep_assert_held(&filter->notify_lock);
1506
1507	list_for_each_entry(cur, &filter->notif->notifications, list) {
1508	if (cur->id == id)
1509	return cur;
1510	}
1511
1512	return NULL;
1513	}
1514
1515	static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync,
1516	void *key)
1517	{
1518	/* Avoid a wakeup if event not interesting for us. */
1519	if (key && !(key_to_poll(key) & (EPOLLIN \| EPOLLERR \| EPOLLHUP)))
1520	return 0;
1521	return autoremove_wake_function(wait, mode, sync, key);
1522	}
1523
1524	static int recv_wait_event(struct seccomp_filter *filter)
1525	{
1526	DEFINE_WAIT_FUNC(wait, recv_wake_function);
1527	int ret;
1528
1529	if (refcount_read(&filter->users) == 0)
1530	return 0;
1531
1532	if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1533	return 0;
1534
1535	for (;;) {
1536	ret = prepare_to_wait_event(&filter->wqh, &wait, TASK_INTERRUPTIBLE);
1537
1538	if (atomic_dec_if_positive(&filter->notif->requests) >= 0)
1539	break;
1540	if (refcount_read(&filter->users) == 0)
1541	break;
1542
1543	if (ret)
1544	return ret;
1545
1546	schedule();
1547	}
1548	finish_wait(&filter->wqh, &wait);
1549	return 0;
1550	}
1551
1552	static long seccomp_notify_recv(struct seccomp_filter *filter,
1553	void __user *buf)
1554	{
1555	struct seccomp_knotif knotif = NULL, cur;
1556	struct seccomp_notif unotif;
1557	ssize_t ret;
1558
1559	/* Verify that we're not given garbage to keep struct extensible. */
1560	ret = check_zeroed_user(buf, sizeof(unotif));
1561	if (ret < 0)
1562	return ret;
1563	if (!ret)
1564	return -EINVAL;
1565
1566	memset(&unotif, 0, sizeof(unotif));
1567
1568	ret = recv_wait_event(filter);
1569	if (ret < 0)
1570	return ret;
1571
1572	mutex_lock(&filter->notify_lock);
1573	list_for_each_entry(cur, &filter->notif->notifications, list) {
1574	if (cur->state == SECCOMP_NOTIFY_INIT) {
1575	knotif = cur;
1576	break;
1577	}
1578	}
1579
1580	/*
1581	* If we didn't find a notification, it could be that the task was
1582	* interrupted by a fatal signal between the time we were woken and
1583	* when we were able to acquire the rw lock.
1584	*/
1585	if (!knotif) {
1586	ret = -ENOENT;
1587	goto out;
1588	}
1589
1590	unotif.id = knotif->id;
1591	unotif.pid = task_pid_vnr(knotif->task);
1592	unotif.data = *(knotif->data);
1593
1594	knotif->state = SECCOMP_NOTIFY_SENT;
1595	wake_up_poll(&filter->wqh, EPOLLOUT \| EPOLLWRNORM);
1596	ret = 0;
1597	out:
1598	mutex_unlock(&filter->notify_lock);
1599
1600	if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1601	ret = -EFAULT;
1602
1603	/*
1604	* Userspace screwed up. To make sure that we keep this
1605	* notification alive, let's reset it back to INIT. It
1606	* may have died when we released the lock, so we need to make
1607	* sure it's still around.
1608	*/
1609	mutex_lock(&filter->notify_lock);
1610	knotif = find_notification(filter, unotif.id);
1611	if (knotif) {
1612	/* Reset the process to make sure it's not stuck */
1613	if (should_sleep_killable(filter, knotif))
1614	complete(&knotif->ready);
1615	knotif->state = SECCOMP_NOTIFY_INIT;
1616	atomic_inc(&filter->notif->requests);
1617	wake_up_poll(&filter->wqh, EPOLLIN \| EPOLLRDNORM);
1618	}
1619	mutex_unlock(&filter->notify_lock);
1620	}
1621
1622	return ret;
1623	}
1624
1625	static long seccomp_notify_send(struct seccomp_filter *filter,
1626	void __user *buf)
1627	{
1628	struct seccomp_notif_resp resp = {};
1629	struct seccomp_knotif *knotif;
1630	long ret;
1631
1632	if (copy_from_user(&resp, buf, sizeof(resp)))
1633	return -EFAULT;
1634
1635	if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1636	return -EINVAL;
1637
1638	if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1639	(resp.error \|\| resp.val))
1640	return -EINVAL;
1641
1642	ret = mutex_lock_interruptible(&filter->notify_lock);
1643	if (ret < 0)
1644	return ret;
1645
1646	knotif = find_notification(filter, resp.id);
1647	if (!knotif) {
1648	ret = -ENOENT;
1649	goto out;
1650	}
1651
1652	/* Allow exactly one reply. */
1653	if (knotif->state != SECCOMP_NOTIFY_SENT) {
1654	ret = -EINPROGRESS;
1655	goto out;
1656	}
1657
1658	ret = 0;
1659	knotif->state = SECCOMP_NOTIFY_REPLIED;
1660	knotif->error = resp.error;
1661	knotif->val = resp.val;
1662	knotif->flags = resp.flags;
1663	if (filter->notif->flags & SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1664	complete_on_current_cpu(&knotif->ready);
1665	else
1666	complete(&knotif->ready);
1667	out:
1668	mutex_unlock(&filter->notify_lock);
1669	return ret;
1670	}
1671
1672	static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1673	void __user *buf)
1674	{
1675	struct seccomp_knotif *knotif;
1676	u64 id;
1677	long ret;
1678
1679	if (copy_from_user(&id, buf, sizeof(id)))
1680	return -EFAULT;
1681
1682	ret = mutex_lock_interruptible(&filter->notify_lock);
1683	if (ret < 0)
1684	return ret;
1685
1686	knotif = find_notification(filter, id);
1687	if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1688	ret = 0;
1689	else
1690	ret = -ENOENT;
1691
1692	mutex_unlock(&filter->notify_lock);
1693	return ret;
1694	}
1695
1696	static long seccomp_notify_set_flags(struct seccomp_filter *filter,
1697	unsigned long flags)
1698	{
1699	long ret;
1700
1701	if (flags & ~SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP)
1702	return -EINVAL;
1703
1704	ret = mutex_lock_interruptible(&filter->notify_lock);
1705	if (ret < 0)
1706	return ret;
1707	filter->notif->flags = flags;
1708	mutex_unlock(&filter->notify_lock);
1709	return 0;
1710	}
1711
1712	static long seccomp_notify_addfd(struct seccomp_filter *filter,
1713	struct seccomp_notif_addfd __user *uaddfd,
1714	unsigned int size)
1715	{
1716	struct seccomp_notif_addfd addfd;
1717	struct seccomp_knotif *knotif;
1718	struct seccomp_kaddfd kaddfd;
1719	int ret;
1720
1721	BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1722	BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1723
1724	if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 \|\| size >= PAGE_SIZE)
1725	return -EINVAL;
1726
1727	ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1728	if (ret)
1729	return ret;
1730
1731	if (addfd.newfd_flags & ~O_CLOEXEC)
1732	return -EINVAL;
1733
1734	if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD \| SECCOMP_ADDFD_FLAG_SEND))
1735	return -EINVAL;
1736
1737	if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1738	return -EINVAL;
1739
1740	kaddfd.file = fget(addfd.srcfd);
1741	if (!kaddfd.file)
1742	return -EBADF;
1743
1744	kaddfd.ioctl_flags = addfd.flags;
1745	kaddfd.flags = addfd.newfd_flags;
1746	kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1747	kaddfd.fd = addfd.newfd;
1748	init_completion(&kaddfd.completion);
1749
1750	ret = mutex_lock_interruptible(&filter->notify_lock);
1751	if (ret < 0)
1752	goto out;
1753
1754	knotif = find_notification(filter, addfd.id);
1755	if (!knotif) {
1756	ret = -ENOENT;
1757	goto out_unlock;
1758	}
1759
1760	/*
1761	* We do not want to allow for FD injection to occur before the
1762	* notification has been picked up by a userspace handler, or after
1763	* the notification has been replied to.
1764	*/
1765	if (knotif->state != SECCOMP_NOTIFY_SENT) {
1766	ret = -EINPROGRESS;
1767	goto out_unlock;
1768	}
1769
1770	if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1771	/*
1772	* Disallow queuing an atomic addfd + send reply while there are
1773	* some addfd requests still to process.
1774	*
1775	* There is no clear reason to support it and allows us to keep
1776	* the loop on the other side straight-forward.
1777	*/
1778	if (!list_empty(&knotif->addfd)) {
1779	ret = -EBUSY;
1780	goto out_unlock;
1781	}
1782
1783	/* Allow exactly only one reply */
1784	knotif->state = SECCOMP_NOTIFY_REPLIED;
1785	}
1786
1787	list_add(&kaddfd.list, &knotif->addfd);
1788	complete(&knotif->ready);
1789	mutex_unlock(&filter->notify_lock);
1790
1791	/* Now we wait for it to be processed or be interrupted */
1792	ret = wait_for_completion_interruptible(&kaddfd.completion);
1793	if (ret == 0) {
1794	/*
1795	* We had a successful completion. The other side has already
1796	* removed us from the addfd queue, and
1797	* wait_for_completion_interruptible has a memory barrier upon
1798	* success that lets us read this value directly without
1799	* locking.
1800	*/
1801	ret = kaddfd.ret;
1802	goto out;
1803	}
1804
1805	mutex_lock(&filter->notify_lock);
1806	/*
1807	* Even though we were woken up by a signal and not a successful
1808	* completion, a completion may have happened in the mean time.
1809	*
1810	* We need to check again if the addfd request has been handled,
1811	* and if not, we will remove it from the queue.
1812	*/
1813	if (list_empty(&kaddfd.list))
1814	ret = kaddfd.ret;
1815	else
1816	list_del(&kaddfd.list);
1817
1818	out_unlock:
1819	mutex_unlock(&filter->notify_lock);
1820	out:
1821	fput(kaddfd.file);
1822
1823	return ret;
1824	}
1825
1826	static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1827	unsigned long arg)
1828	{
1829	struct seccomp_filter *filter = file->private_data;
1830	void __user buf = (void __user )arg;
1831
1832	/* Fixed-size ioctls */
1833	switch (cmd) {
1834	case SECCOMP_IOCTL_NOTIF_RECV:
1835	return seccomp_notify_recv(filter, buf);
1836	case SECCOMP_IOCTL_NOTIF_SEND:
1837	return seccomp_notify_send(filter, buf);
1838	case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1839	case SECCOMP_IOCTL_NOTIF_ID_VALID:
1840	return seccomp_notify_id_valid(filter, buf);
1841	case SECCOMP_IOCTL_NOTIF_SET_FLAGS:
1842	return seccomp_notify_set_flags(filter, arg);
1843	}
1844
1845	/* Extensible Argument ioctls */
1846	#define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT \| IOCSIZE_MASK))
1847	switch (EA_IOCTL(cmd)) {
1848	case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1849	return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1850	default:
1851	return -EINVAL;
1852	}
1853	}
1854
1855	static __poll_t seccomp_notify_poll(struct file *file,
1856	struct poll_table_struct *poll_tab)
1857	{
1858	struct seccomp_filter *filter = file->private_data;
1859	__poll_t ret = 0;
1860	struct seccomp_knotif *cur;
1861
1862	poll_wait(file, &filter->wqh, poll_tab);
1863
1864	if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1865	return EPOLLERR;
1866
1867	list_for_each_entry(cur, &filter->notif->notifications, list) {
1868	if (cur->state == SECCOMP_NOTIFY_INIT)
1869	ret \|= EPOLLIN \| EPOLLRDNORM;
1870	if (cur->state == SECCOMP_NOTIFY_SENT)
1871	ret \|= EPOLLOUT \| EPOLLWRNORM;
1872	if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1873	break;
1874	}
1875
1876	mutex_unlock(&filter->notify_lock);
1877
1878	if (refcount_read(&filter->users) == 0)
1879	ret \|= EPOLLHUP;
1880
1881	return ret;
1882	}
1883
1884	static const struct file_operations seccomp_notify_ops = {
1885	.poll = seccomp_notify_poll,
1886	.release = seccomp_notify_release,
1887	.unlocked_ioctl = seccomp_notify_ioctl,
1888	.compat_ioctl = seccomp_notify_ioctl,
1889	};
1890
1891	static struct file init_listener(struct seccomp_filter filter)
1892	{
1893	struct file *ret;
1894
1895	ret = ERR_PTR(-ENOMEM);
1896	filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1897	if (!filter->notif)
1898	goto out;
1899
1900	filter->notif->next_id = get_random_u64();
1901	INIT_LIST_HEAD(&filter->notif->notifications);
1902
1903	ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1904	filter, O_RDWR);
1905	if (IS_ERR(ret))
1906	goto out_notif;
1907
1908	/* The file has a reference to it now */
1909	__get_seccomp_filter(filter);
1910
1911	out_notif:
1912	if (IS_ERR(ret))
1913	seccomp_notify_free(filter);
1914	out:
1915	return ret;
1916	}
1917
1918	/*
1919	* Does @new_child have a listener while an ancestor also has a listener?
1920	* If so, we'll want to reject this filter.
1921	* This only has to be tested for the current process, even in the TSYNC case,
1922	* because TSYNC installs @child with the same parent on all threads.
1923	* Note that @new_child is not hooked up to its parent at this point yet, so
1924	* we use current->seccomp.filter.
1925	*/
1926	static bool has_duplicate_listener(struct seccomp_filter *new_child)
1927	{
1928	struct seccomp_filter *cur;
1929
1930	/* must be protected against concurrent TSYNC */
1931	lockdep_assert_held(&current->sighand->siglock);
1932
1933	if (!new_child->notif)
1934	return false;
1935	for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1936	if (cur->notif)
1937	return true;
1938	}
1939
1940	return false;
1941	}
1942
1943	/**
1944	* seccomp_set_mode_filter: internal function for setting seccomp filter
1945	* @flags: flags to change filter behavior
1946	* @filter: struct sock_fprog containing filter
1947	*
1948	* This function may be called repeatedly to install additional filters.
1949	* Every filter successfully installed will be evaluated (in reverse order)
1950	* for each system call the task makes.
1951	*
1952	* Once current->seccomp.mode is non-zero, it may not be changed.
1953	*
1954	* Returns 0 on success or -EINVAL on failure.
1955	*/
1956	static long seccomp_set_mode_filter(unsigned int flags,
1957	const char __user *filter)
1958	{
1959	const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1960	struct seccomp_filter *prepared = NULL;
1961	long ret = -EINVAL;
1962	int listener = -1;
1963	struct file *listener_f = NULL;
1964
1965	/* Validate flags. */
1966	if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1967	return -EINVAL;
1968
1969	/*
1970	* In the successful case, NEW_LISTENER returns the new listener fd.
1971	* But in the failure case, TSYNC returns the thread that died. If you
1972	* combine these two flags, there's no way to tell whether something
1973	* succeeded or failed. So, let's disallow this combination if the user
1974	* has not explicitly requested no errors from TSYNC.
1975	*/
1976	if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1977	(flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1978	((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1979	return -EINVAL;
1980
1981	/*
1982	* The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1983	* without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1984	*/
1985	if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1986	((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1987	return -EINVAL;
1988
1989	/* Prepare the new filter before holding any locks. */
1990	prepared = seccomp_prepare_user_filter(filter);
1991	if (IS_ERR(prepared))
1992	return PTR_ERR(prepared);
1993
1994	if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1995	listener = get_unused_fd_flags(O_CLOEXEC);
1996	if (listener < 0) {
1997	ret = listener;
1998	goto out_free;
1999	}
2000
2001	listener_f = init_listener(prepared);
2002	if (IS_ERR(listener_f)) {
2003	put_unused_fd(listener);
2004	ret = PTR_ERR(listener_f);
2005	goto out_free;
2006	}
2007	}
2008
2009	/*
2010	* Make sure we cannot change seccomp or nnp state via TSYNC
2011	* while another thread is in the middle of calling exec.
2012	*/
2013	if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
2014	mutex_lock_killable(&current->signal->cred_guard_mutex))
2015	goto out_put_fd;
2016
2017	spin_lock_irq(&current->sighand->siglock);
2018
2019	if (!seccomp_may_assign_mode(seccomp_mode))
2020	goto out;
2021
2022	if (has_duplicate_listener(prepared)) {
2023	ret = -EBUSY;
2024	goto out;
2025	}
2026
2027	ret = seccomp_attach_filter(flags, prepared);
2028	if (ret)
2029	goto out;
2030	/* Do not free the successfully attached filter. */
2031	prepared = NULL;
2032
2033	seccomp_assign_mode(current, seccomp_mode, flags);
2034	out:
2035	spin_unlock_irq(&current->sighand->siglock);
2036	if (flags & SECCOMP_FILTER_FLAG_TSYNC)
2037	mutex_unlock(&current->signal->cred_guard_mutex);
2038	out_put_fd:
2039	if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
2040	if (ret) {
2041	listener_f->private_data = NULL;
2042	fput(listener_f);
2043	put_unused_fd(listener);
2044	seccomp_notify_detach(prepared);
2045	} else {
2046	fd_install(listener, listener_f);
2047	ret = listener;
2048	}
2049	}
2050	out_free:
2051	seccomp_filter_free(prepared);
2052	return ret;
2053	}
2054	#else
2055	static inline long seccomp_set_mode_filter(unsigned int flags,
2056	const char __user *filter)
2057	{
2058	return -EINVAL;
2059	}
2060	#endif
2061
2062	static long seccomp_get_action_avail(const char __user *uaction)
2063	{
2064	u32 action;
2065
2066	if (copy_from_user(&action, uaction, sizeof(action)))
2067	return -EFAULT;
2068
2069	switch (action) {
2070	case SECCOMP_RET_KILL_PROCESS:
2071	case SECCOMP_RET_KILL_THREAD:
2072	case SECCOMP_RET_TRAP:
2073	case SECCOMP_RET_ERRNO:
2074	case SECCOMP_RET_USER_NOTIF:
2075	case SECCOMP_RET_TRACE:
2076	case SECCOMP_RET_LOG:
2077	case SECCOMP_RET_ALLOW:
2078	break;
2079	default:
2080	return -EOPNOTSUPP;
2081	}
2082
2083	return 0;
2084	}
2085
2086	static long seccomp_get_notif_sizes(void __user *usizes)
2087	{
2088	struct seccomp_notif_sizes sizes = {
2089	.seccomp_notif = sizeof(struct seccomp_notif),
2090	.seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
2091	.seccomp_data = sizeof(struct seccomp_data),
2092	};
2093
2094	if (copy_to_user(usizes, &sizes, sizeof(sizes)))
2095	return -EFAULT;
2096
2097	return 0;
2098	}
2099
2100	/* Common entry point for both prctl and syscall. */
2101	static long do_seccomp(unsigned int op, unsigned int flags,
2102	void __user *uargs)
2103	{
2104	switch (op) {
2105	case SECCOMP_SET_MODE_STRICT:
2106	if (flags != 0 \|\| uargs != NULL)
2107	return -EINVAL;
2108	return seccomp_set_mode_strict();
2109	case SECCOMP_SET_MODE_FILTER:
2110	return seccomp_set_mode_filter(flags, uargs);
2111	case SECCOMP_GET_ACTION_AVAIL:
2112	if (flags != 0)
2113	return -EINVAL;
2114
2115	return seccomp_get_action_avail(uargs);
2116	case SECCOMP_GET_NOTIF_SIZES:
2117	if (flags != 0)
2118	return -EINVAL;
2119
2120	return seccomp_get_notif_sizes(uargs);
2121	default:
2122	return -EINVAL;
2123	}
2124	}
2125
2126	SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
2127	void __user *, uargs)
2128	{
2129	return do_seccomp(op, flags, uargs);
2130	}
2131
2132	/**
2133	* prctl_set_seccomp: configures current->seccomp.mode
2134	* @seccomp_mode: requested mode to use
2135	* @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2136	*
2137	* Returns 0 on success or -EINVAL on failure.
2138	*/
2139	long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2140	{
2141	unsigned int op;
2142	void __user *uargs;
2143
2144	switch (seccomp_mode) {
2145	case SECCOMP_MODE_STRICT:
2146	op = SECCOMP_SET_MODE_STRICT;
2147	/*
2148	* Setting strict mode through prctl always ignored filter,
2149	* so make sure it is always NULL here to pass the internal
2150	* check in do_seccomp().
2151	*/
2152	uargs = NULL;
2153	break;
2154	case SECCOMP_MODE_FILTER:
2155	op = SECCOMP_SET_MODE_FILTER;
2156	uargs = filter;
2157	break;
2158	default:
2159	return -EINVAL;
2160	}
2161
2162	/* prctl interface doesn't have flags, so they are always zero. */
2163	return do_seccomp(op, 0, uargs);
2164	}
2165
2166	#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2167	static struct seccomp_filter get_nth_filter(struct task_struct task,
2168	unsigned long filter_off)
2169	{
2170	struct seccomp_filter orig, filter;
2171	unsigned long count;
2172
2173	/*
2174	* Note: this is only correct because the caller should be the (ptrace)
2175	* tracer of the task, otherwise lock_task_sighand is needed.
2176	*/
2177	spin_lock_irq(&task->sighand->siglock);
2178
2179	if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2180	spin_unlock_irq(&task->sighand->siglock);
2181	return ERR_PTR(-EINVAL);
2182	}
2183
2184	orig = task->seccomp.filter;
2185	__get_seccomp_filter(orig);
2186	spin_unlock_irq(&task->sighand->siglock);
2187
2188	count = 0;
2189	for (filter = orig; filter; filter = filter->prev)
2190	count++;
2191
2192	if (filter_off >= count) {
2193	filter = ERR_PTR(-ENOENT);
2194	goto out;
2195	}
2196
2197	count -= filter_off;
2198	for (filter = orig; filter && count > 1; filter = filter->prev)
2199	count--;
2200
2201	if (WARN_ON(count != 1 \|\| !filter)) {
2202	filter = ERR_PTR(-ENOENT);
2203	goto out;
2204	}
2205
2206	__get_seccomp_filter(filter);
2207
2208	out:
2209	__put_seccomp_filter(orig);
2210	return filter;
2211	}
2212
2213	long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2214	void __user *data)
2215	{
2216	struct seccomp_filter *filter;
2217	struct sock_fprog_kern *fprog;
2218	long ret;
2219
2220	if (!capable(CAP_SYS_ADMIN) \|\|
2221	current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2222	return -EACCES;
2223	}
2224
2225	filter = get_nth_filter(task, filter_off);
2226	if (IS_ERR(filter))
2227	return PTR_ERR(filter);
2228
2229	fprog = filter->prog->orig_prog;
2230	if (!fprog) {
2231	/* This must be a new non-cBPF filter, since we save
2232	* every cBPF filter's orig_prog above when
2233	* CONFIG_CHECKPOINT_RESTORE is enabled.
2234	*/
2235	ret = -EMEDIUMTYPE;
2236	goto out;
2237	}
2238
2239	ret = fprog->len;
2240	if (!data)
2241	goto out;
2242
2243	if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2244	ret = -EFAULT;
2245
2246	out:
2247	__put_seccomp_filter(filter);
2248	return ret;
2249	}
2250
2251	long seccomp_get_metadata(struct task_struct *task,
2252	unsigned long size, void __user *data)
2253	{
2254	long ret;
2255	struct seccomp_filter *filter;
2256	struct seccomp_metadata kmd = {};
2257
2258	if (!capable(CAP_SYS_ADMIN) \|\|
2259	current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2260	return -EACCES;
2261	}
2262
2263	size = min_t(unsigned long, size, sizeof(kmd));
2264
2265	if (size < sizeof(kmd.filter_off))
2266	return -EINVAL;
2267
2268	if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2269	return -EFAULT;
2270
2271	filter = get_nth_filter(task, kmd.filter_off);
2272	if (IS_ERR(filter))
2273	return PTR_ERR(filter);
2274
2275	if (filter->log)
2276	kmd.flags \|= SECCOMP_FILTER_FLAG_LOG;
2277
2278	ret = size;
2279	if (copy_to_user(data, &kmd, size))
2280	ret = -EFAULT;
2281
2282	__put_seccomp_filter(filter);
2283	return ret;
2284	}
2285	#endif
2286
2287	#ifdef CONFIG_SYSCTL
2288
2289	/* Human readable action names for friendly sysctl interaction */
2290	#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2291	#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2292	#define SECCOMP_RET_TRAP_NAME "trap"
2293	#define SECCOMP_RET_ERRNO_NAME "errno"
2294	#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2295	#define SECCOMP_RET_TRACE_NAME "trace"
2296	#define SECCOMP_RET_LOG_NAME "log"
2297	#define SECCOMP_RET_ALLOW_NAME "allow"
2298
2299	static const char seccomp_actions_avail[] =
2300	SECCOMP_RET_KILL_PROCESS_NAME " "
2301	SECCOMP_RET_KILL_THREAD_NAME " "
2302	SECCOMP_RET_TRAP_NAME " "
2303	SECCOMP_RET_ERRNO_NAME " "
2304	SECCOMP_RET_USER_NOTIF_NAME " "
2305	SECCOMP_RET_TRACE_NAME " "
2306	SECCOMP_RET_LOG_NAME " "
2307	SECCOMP_RET_ALLOW_NAME;
2308
2309	struct seccomp_log_name {
2310	u32 log;
2311	const char *name;
2312	};
2313
2314	static const struct seccomp_log_name seccomp_log_names[] = {
2315	{ SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2316	{ SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2317	{ SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2318	{ SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2319	{ SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2320	{ SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2321	{ SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2322	{ SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2323	{ }
2324	};
2325
2326	static bool seccomp_names_from_actions_logged(char *names, size_t size,
2327	u32 actions_logged,
2328	const char *sep)
2329	{
2330	const struct seccomp_log_name *cur;
2331	bool append_sep = false;
2332
2333	for (cur = seccomp_log_names; cur->name && size; cur++) {
2334	ssize_t ret;
2335
2336	if (!(actions_logged & cur->log))
2337	continue;
2338
2339	if (append_sep) {
2340	ret = strscpy(names, sep, size);
2341	if (ret < 0)
2342	return false;
2343
2344	names += ret;
2345	size -= ret;
2346	} else
2347	append_sep = true;
2348
2349	ret = strscpy(names, cur->name, size);
2350	if (ret < 0)
2351	return false;
2352
2353	names += ret;
2354	size -= ret;
2355	}
2356
2357	return true;
2358	}
2359
2360	static bool seccomp_action_logged_from_name(u32 *action_logged,
2361	const char *name)
2362	{
2363	const struct seccomp_log_name *cur;
2364
2365	for (cur = seccomp_log_names; cur->name; cur++) {
2366	if (!strcmp(cur->name, name)) {
2367	*action_logged = cur->log;
2368	return true;
2369	}
2370	}
2371
2372	return false;
2373	}
2374
2375	static bool seccomp_actions_logged_from_names(u32 actions_logged, char names)
2376	{
2377	char *name;
2378
2379	*actions_logged = 0;
2380	while ((name = strsep(&names, " ")) && *name) {
2381	u32 action_logged = 0;
2382
2383	if (!seccomp_action_logged_from_name(&action_logged, name))
2384	return false;
2385
2386	*actions_logged \|= action_logged;
2387	}
2388
2389	return true;
2390	}
2391
2392	static int read_actions_logged(const struct ctl_table ro_table, void buffer,
2393	size_t lenp, loff_t ppos)
2394	{
2395	char names[sizeof(seccomp_actions_avail)];
2396	struct ctl_table table;
2397
2398	memset(names, 0, sizeof(names));
2399
2400	if (!seccomp_names_from_actions_logged(names, sizeof(names),
2401	seccomp_actions_logged, " "))
2402	return -EINVAL;
2403
2404	table = *ro_table;
2405	table.data = names;
2406	table.maxlen = sizeof(names);
2407	return proc_dostring(&table, 0, buffer, lenp, ppos);
2408	}
2409
2410	static int write_actions_logged(const struct ctl_table ro_table, void buffer,
2411	size_t lenp, loff_t ppos, u32 *actions_logged)
2412	{
2413	char names[sizeof(seccomp_actions_avail)];
2414	struct ctl_table table;
2415	int ret;
2416
2417	if (!capable(CAP_SYS_ADMIN))
2418	return -EPERM;
2419
2420	memset(names, 0, sizeof(names));
2421
2422	table = *ro_table;
2423	table.data = names;
2424	table.maxlen = sizeof(names);
2425	ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2426	if (ret)
2427	return ret;
2428
2429	if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2430	return -EINVAL;
2431
2432	if (*actions_logged & SECCOMP_LOG_ALLOW)
2433	return -EINVAL;
2434
2435	seccomp_actions_logged = *actions_logged;
2436	return 0;
2437	}
2438
2439	static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2440	int ret)
2441	{
2442	char names[sizeof(seccomp_actions_avail)];
2443	char old_names[sizeof(seccomp_actions_avail)];
2444	const char *new = names;
2445	const char *old = old_names;
2446
2447	if (!audit_enabled)
2448	return;
2449
2450	memset(names, 0, sizeof(names));
2451	memset(old_names, 0, sizeof(old_names));
2452
2453	if (ret)
2454	new = "?";
2455	else if (!actions_logged)
2456	new = "(none)";
2457	else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2458	actions_logged, ","))
2459	new = "?";
2460
2461	if (!old_actions_logged)
2462	old = "(none)";
2463	else if (!seccomp_names_from_actions_logged(old_names,
2464	sizeof(old_names),
2465	old_actions_logged, ","))
2466	old = "?";
2467
2468	return audit_seccomp_actions_logged(new, old, !ret);
2469	}
2470
2471	static int seccomp_actions_logged_handler(const struct ctl_table *ro_table, int write,
2472	void buffer, size_t lenp,
2473	loff_t *ppos)
2474	{
2475	int ret;
2476
2477	if (write) {
2478	u32 actions_logged = 0;
2479	u32 old_actions_logged = seccomp_actions_logged;
2480
2481	ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2482	&actions_logged);
2483	audit_actions_logged(actions_logged, old_actions_logged, ret);
2484	} else
2485	ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2486
2487	return ret;
2488	}
2489
2490	static const struct ctl_table seccomp_sysctl_table[] = {
2491	{
2492	.procname = "actions_avail",
2493	.data = (void *) &seccomp_actions_avail,
2494	.maxlen = sizeof(seccomp_actions_avail),
2495	.mode = 0444,
2496	.proc_handler = proc_dostring,
2497	},
2498	{
2499	.procname = "actions_logged",
2500	.mode = 0644,
2501	.proc_handler = seccomp_actions_logged_handler,
2502	},
2503	};
2504
2505	static int __init seccomp_sysctl_init(void)
2506	{
2507	register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
2508	return 0;
2509	}
2510
2511	device_initcall(seccomp_sysctl_init)
2512
2513	#endif /* CONFIG_SYSCTL */
2514
2515	#ifdef CONFIG_SECCOMP_CACHE_DEBUG
2516	/* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2517	static void proc_pid_seccomp_cache_arch(struct seq_file m, const char name,
2518	const void *bitmap, size_t bitmap_size)
2519	{
2520	int nr;
2521
2522	for (nr = 0; nr < bitmap_size; nr++) {
2523	bool cached = test_bit(nr, bitmap);
2524	char *status = cached ? "ALLOW" : "FILTER";
2525
2526	seq_printf(m, "%s %d %s\n", name, nr, status);
2527	}
2528	}
2529
2530	int proc_pid_seccomp_cache(struct seq_file m, struct pid_namespace ns,
2531	struct pid pid, struct task_struct task)
2532	{
2533	struct seccomp_filter *f;
2534	unsigned long flags;
2535
2536	/*
2537	* We don't want some sandboxed process to know what their seccomp
2538	* filters consist of.
2539	*/
2540	if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2541	return -EACCES;
2542
2543	if (!lock_task_sighand(task, &flags))
2544	return -ESRCH;
2545
2546	f = READ_ONCE(task->seccomp.filter);
2547	if (!f) {
2548	unlock_task_sighand(task, &flags);
2549	return 0;
2550	}
2551
2552	/* prevent filter from being freed while we are printing it */
2553	__get_seccomp_filter(f);
2554	unlock_task_sighand(task, &flags);
2555
2556	proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2557	f->cache.allow_native,
2558	SECCOMP_ARCH_NATIVE_NR);
2559
2560	#ifdef SECCOMP_ARCH_COMPAT
2561	proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2562	f->cache.allow_compat,
2563	SECCOMP_ARCH_COMPAT_NR);
2564	#endif /* SECCOMP_ARCH_COMPAT */
2565
2566	__put_seccomp_filter(f);
2567	return 0;
2568	}
2569	#endif /* CONFIG_SECCOMP_CACHE_DEBUG */