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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
17#include <linux/refcount.h>
18#include <linux/audit.h>
19#include <linux/compat.h>
20#include <linux/coredump.h>
21#include <linux/kmemleak.h>
22#include <linux/nospec.h>
23#include <linux/prctl.h>
24#include <linux/sched.h>
25#include <linux/sched/task_stack.h>
26#include <linux/seccomp.h>
27#include <linux/slab.h>
28#include <linux/syscalls.h>
29#include <linux/sysctl.h>
30
31#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
32#include <asm/syscall.h>
33#endif
34
35#ifdef CONFIG_SECCOMP_FILTER
36#include <linux/file.h>
37#include <linux/filter.h>
38#include <linux/pid.h>
39#include <linux/ptrace.h>
40#include <linux/security.h>
41#include <linux/tracehook.h>
42#include <linux/uaccess.h>
43#include <linux/anon_inodes.h>
44
45enum notify_state {
46 SECCOMP_NOTIFY_INIT,
47 SECCOMP_NOTIFY_SENT,
48 SECCOMP_NOTIFY_REPLIED,
49};
50
51struct seccomp_knotif {
52 /* The struct pid of the task whose filter triggered the notification */
53 struct task_struct *task;
54
55 /* The "cookie" for this request; this is unique for this filter. */
56 u64 id;
57
58 /*
59 * The seccomp data. This pointer is valid the entire time this
60 * notification is active, since it comes from __seccomp_filter which
61 * eclipses the entire lifecycle here.
62 */
63 const struct seccomp_data *data;
64
65 /*
66 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
67 * struct seccomp_knotif is created and starts out in INIT. Once the
68 * handler reads the notification off of an FD, it transitions to SENT.
69 * If a signal is received the state transitions back to INIT and
70 * another message is sent. When the userspace handler replies, state
71 * transitions to REPLIED.
72 */
73 enum notify_state state;
74
75 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
76 int error;
77 long val;
78
79 /* Signals when this has entered SECCOMP_NOTIFY_REPLIED */
80 struct completion ready;
81
82 struct list_head list;
83};
84
85/**
86 * struct notification - container for seccomp userspace notifications. Since
87 * most seccomp filters will not have notification listeners attached and this
88 * structure is fairly large, we store the notification-specific stuff in a
89 * separate structure.
90 *
91 * @request: A semaphore that users of this notification can wait on for
92 * changes. Actual reads and writes are still controlled with
93 * filter->notify_lock.
94 * @next_id: The id of the next request.
95 * @notifications: A list of struct seccomp_knotif elements.
96 * @wqh: A wait queue for poll.
97 */
98struct notification {
99 struct semaphore request;
100 u64 next_id;
101 struct list_head notifications;
102 wait_queue_head_t wqh;
103};
104
105/**
106 * struct seccomp_filter - container for seccomp BPF programs
107 *
108 * @usage: reference count to manage the object lifetime.
109 * get/put helpers should be used when accessing an instance
110 * outside of a lifetime-guarded section. In general, this
111 * is only needed for handling filters shared across tasks.
112 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
113 * @prev: points to a previously installed, or inherited, filter
114 * @prog: the BPF program to evaluate
115 * @notif: the struct that holds all notification related information
116 * @notify_lock: A lock for all notification-related accesses.
117 *
118 * seccomp_filter objects are organized in a tree linked via the @prev
119 * pointer. For any task, it appears to be a singly-linked list starting
120 * with current->seccomp.filter, the most recently attached or inherited filter.
121 * However, multiple filters may share a @prev node, by way of fork(), which
122 * results in a unidirectional tree existing in memory. This is similar to
123 * how namespaces work.
124 *
125 * seccomp_filter objects should never be modified after being attached
126 * to a task_struct (other than @usage).
127 */
128struct seccomp_filter {
129 refcount_t usage;
130 bool log;
131 struct seccomp_filter *prev;
132 struct bpf_prog *prog;
133 struct notification *notif;
134 struct mutex notify_lock;
135};
136
137/* Limit any path through the tree to 256KB worth of instructions. */
138#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
139
140/*
141 * Endianness is explicitly ignored and left for BPF program authors to manage
142 * as per the specific architecture.
143 */
144static void populate_seccomp_data(struct seccomp_data *sd)
145{
146 struct task_struct *task = current;
147 struct pt_regs *regs = task_pt_regs(task);
148 unsigned long args[6];
149
150 sd->nr = syscall_get_nr(task, regs);
151 sd->arch = syscall_get_arch();
152 syscall_get_arguments(task, regs, 0, 6, args);
153 sd->args[0] = args[0];
154 sd->args[1] = args[1];
155 sd->args[2] = args[2];
156 sd->args[3] = args[3];
157 sd->args[4] = args[4];
158 sd->args[5] = args[5];
159 sd->instruction_pointer = KSTK_EIP(task);
160}
161
162/**
163 * seccomp_check_filter - verify seccomp filter code
164 * @filter: filter to verify
165 * @flen: length of filter
166 *
167 * Takes a previously checked filter (by bpf_check_classic) and
168 * redirects all filter code that loads struct sk_buff data
169 * and related data through seccomp_bpf_load. It also
170 * enforces length and alignment checking of those loads.
171 *
172 * Returns 0 if the rule set is legal or -EINVAL if not.
173 */
174static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
175{
176 int pc;
177 for (pc = 0; pc < flen; pc++) {
178 struct sock_filter *ftest = &filter[pc];
179 u16 code = ftest->code;
180 u32 k = ftest->k;
181
182 switch (code) {
183 case BPF_LD | BPF_W | BPF_ABS:
184 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
185 /* 32-bit aligned and not out of bounds. */
186 if (k >= sizeof(struct seccomp_data) || k & 3)
187 return -EINVAL;
188 continue;
189 case BPF_LD | BPF_W | BPF_LEN:
190 ftest->code = BPF_LD | BPF_IMM;
191 ftest->k = sizeof(struct seccomp_data);
192 continue;
193 case BPF_LDX | BPF_W | BPF_LEN:
194 ftest->code = BPF_LDX | BPF_IMM;
195 ftest->k = sizeof(struct seccomp_data);
196 continue;
197 /* Explicitly include allowed calls. */
198 case BPF_RET | BPF_K:
199 case BPF_RET | BPF_A:
200 case BPF_ALU | BPF_ADD | BPF_K:
201 case BPF_ALU | BPF_ADD | BPF_X:
202 case BPF_ALU | BPF_SUB | BPF_K:
203 case BPF_ALU | BPF_SUB | BPF_X:
204 case BPF_ALU | BPF_MUL | BPF_K:
205 case BPF_ALU | BPF_MUL | BPF_X:
206 case BPF_ALU | BPF_DIV | BPF_K:
207 case BPF_ALU | BPF_DIV | BPF_X:
208 case BPF_ALU | BPF_AND | BPF_K:
209 case BPF_ALU | BPF_AND | BPF_X:
210 case BPF_ALU | BPF_OR | BPF_K:
211 case BPF_ALU | BPF_OR | BPF_X:
212 case BPF_ALU | BPF_XOR | BPF_K:
213 case BPF_ALU | BPF_XOR | BPF_X:
214 case BPF_ALU | BPF_LSH | BPF_K:
215 case BPF_ALU | BPF_LSH | BPF_X:
216 case BPF_ALU | BPF_RSH | BPF_K:
217 case BPF_ALU | BPF_RSH | BPF_X:
218 case BPF_ALU | BPF_NEG:
219 case BPF_LD | BPF_IMM:
220 case BPF_LDX | BPF_IMM:
221 case BPF_MISC | BPF_TAX:
222 case BPF_MISC | BPF_TXA:
223 case BPF_LD | BPF_MEM:
224 case BPF_LDX | BPF_MEM:
225 case BPF_ST:
226 case BPF_STX:
227 case BPF_JMP | BPF_JA:
228 case BPF_JMP | BPF_JEQ | BPF_K:
229 case BPF_JMP | BPF_JEQ | BPF_X:
230 case BPF_JMP | BPF_JGE | BPF_K:
231 case BPF_JMP | BPF_JGE | BPF_X:
232 case BPF_JMP | BPF_JGT | BPF_K:
233 case BPF_JMP | BPF_JGT | BPF_X:
234 case BPF_JMP | BPF_JSET | BPF_K:
235 case BPF_JMP | BPF_JSET | BPF_X:
236 continue;
237 default:
238 return -EINVAL;
239 }
240 }
241 return 0;
242}
243
244/**
245 * seccomp_run_filters - evaluates all seccomp filters against @sd
246 * @sd: optional seccomp data to be passed to filters
247 * @match: stores struct seccomp_filter that resulted in the return value,
248 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
249 * be unchanged.
250 *
251 * Returns valid seccomp BPF response codes.
252 */
253#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
254static u32 seccomp_run_filters(const struct seccomp_data *sd,
255 struct seccomp_filter **match)
256{
257 u32 ret = SECCOMP_RET_ALLOW;
258 /* Make sure cross-thread synced filter points somewhere sane. */
259 struct seccomp_filter *f =
260 READ_ONCE(current->seccomp.filter);
261
262 /* Ensure unexpected behavior doesn't result in failing open. */
263 if (WARN_ON(f == NULL))
264 return SECCOMP_RET_KILL_PROCESS;
265
266 /*
267 * All filters in the list are evaluated and the lowest BPF return
268 * value always takes priority (ignoring the DATA).
269 */
270 for (; f; f = f->prev) {
271 u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
272
273 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
274 ret = cur_ret;
275 *match = f;
276 }
277 }
278 return ret;
279}
280#endif /* CONFIG_SECCOMP_FILTER */
281
282static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
283{
284 assert_spin_locked(&current->sighand->siglock);
285
286 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
287 return false;
288
289 return true;
290}
291
292void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
293
294static inline void seccomp_assign_mode(struct task_struct *task,
295 unsigned long seccomp_mode,
296 unsigned long flags)
297{
298 assert_spin_locked(&task->sighand->siglock);
299
300 task->seccomp.mode = seccomp_mode;
301 /*
302 * Make sure TIF_SECCOMP cannot be set before the mode (and
303 * filter) is set.
304 */
305 smp_mb__before_atomic();
306 /* Assume default seccomp processes want spec flaw mitigation. */
307 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
308 arch_seccomp_spec_mitigate(task);
309 set_tsk_thread_flag(task, TIF_SECCOMP);
310}
311
312#ifdef CONFIG_SECCOMP_FILTER
313/* Returns 1 if the parent is an ancestor of the child. */
314static int is_ancestor(struct seccomp_filter *parent,
315 struct seccomp_filter *child)
316{
317 /* NULL is the root ancestor. */
318 if (parent == NULL)
319 return 1;
320 for (; child; child = child->prev)
321 if (child == parent)
322 return 1;
323 return 0;
324}
325
326/**
327 * seccomp_can_sync_threads: checks if all threads can be synchronized
328 *
329 * Expects sighand and cred_guard_mutex locks to be held.
330 *
331 * Returns 0 on success, -ve on error, or the pid of a thread which was
332 * either not in the correct seccomp mode or it did not have an ancestral
333 * seccomp filter.
334 */
335static inline pid_t seccomp_can_sync_threads(void)
336{
337 struct task_struct *thread, *caller;
338
339 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
340 assert_spin_locked(&current->sighand->siglock);
341
342 /* Validate all threads being eligible for synchronization. */
343 caller = current;
344 for_each_thread(caller, thread) {
345 pid_t failed;
346
347 /* Skip current, since it is initiating the sync. */
348 if (thread == caller)
349 continue;
350
351 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
352 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
353 is_ancestor(thread->seccomp.filter,
354 caller->seccomp.filter)))
355 continue;
356
357 /* Return the first thread that cannot be synchronized. */
358 failed = task_pid_vnr(thread);
359 /* If the pid cannot be resolved, then return -ESRCH */
360 if (WARN_ON(failed == 0))
361 failed = -ESRCH;
362 return failed;
363 }
364
365 return 0;
366}
367
368/**
369 * seccomp_sync_threads: sets all threads to use current's filter
370 *
371 * Expects sighand and cred_guard_mutex locks to be held, and for
372 * seccomp_can_sync_threads() to have returned success already
373 * without dropping the locks.
374 *
375 */
376static inline void seccomp_sync_threads(unsigned long flags)
377{
378 struct task_struct *thread, *caller;
379
380 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
381 assert_spin_locked(&current->sighand->siglock);
382
383 /* Synchronize all threads. */
384 caller = current;
385 for_each_thread(caller, thread) {
386 /* Skip current, since it needs no changes. */
387 if (thread == caller)
388 continue;
389
390 /* Get a task reference for the new leaf node. */
391 get_seccomp_filter(caller);
392 /*
393 * Drop the task reference to the shared ancestor since
394 * current's path will hold a reference. (This also
395 * allows a put before the assignment.)
396 */
397 put_seccomp_filter(thread);
398 smp_store_release(&thread->seccomp.filter,
399 caller->seccomp.filter);
400
401 /*
402 * Don't let an unprivileged task work around
403 * the no_new_privs restriction by creating
404 * a thread that sets it up, enters seccomp,
405 * then dies.
406 */
407 if (task_no_new_privs(caller))
408 task_set_no_new_privs(thread);
409
410 /*
411 * Opt the other thread into seccomp if needed.
412 * As threads are considered to be trust-realm
413 * equivalent (see ptrace_may_access), it is safe to
414 * allow one thread to transition the other.
415 */
416 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
417 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
418 flags);
419 }
420}
421
422/**
423 * seccomp_prepare_filter: Prepares a seccomp filter for use.
424 * @fprog: BPF program to install
425 *
426 * Returns filter on success or an ERR_PTR on failure.
427 */
428static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
429{
430 struct seccomp_filter *sfilter;
431 int ret;
432 const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
433
434 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
435 return ERR_PTR(-EINVAL);
436
437 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
438
439 /*
440 * Installing a seccomp filter requires that the task has
441 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
442 * This avoids scenarios where unprivileged tasks can affect the
443 * behavior of privileged children.
444 */
445 if (!task_no_new_privs(current) &&
446 security_capable_noaudit(current_cred(), current_user_ns(),
447 CAP_SYS_ADMIN) != 0)
448 return ERR_PTR(-EACCES);
449
450 /* Allocate a new seccomp_filter */
451 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
452 if (!sfilter)
453 return ERR_PTR(-ENOMEM);
454
455 mutex_init(&sfilter->notify_lock);
456 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
457 seccomp_check_filter, save_orig);
458 if (ret < 0) {
459 kfree(sfilter);
460 return ERR_PTR(ret);
461 }
462
463 refcount_set(&sfilter->usage, 1);
464
465 return sfilter;
466}
467
468/**
469 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
470 * @user_filter: pointer to the user data containing a sock_fprog.
471 *
472 * Returns 0 on success and non-zero otherwise.
473 */
474static struct seccomp_filter *
475seccomp_prepare_user_filter(const char __user *user_filter)
476{
477 struct sock_fprog fprog;
478 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
479
480#ifdef CONFIG_COMPAT
481 if (in_compat_syscall()) {
482 struct compat_sock_fprog fprog32;
483 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
484 goto out;
485 fprog.len = fprog32.len;
486 fprog.filter = compat_ptr(fprog32.filter);
487 } else /* falls through to the if below. */
488#endif
489 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
490 goto out;
491 filter = seccomp_prepare_filter(&fprog);
492out:
493 return filter;
494}
495
496/**
497 * seccomp_attach_filter: validate and attach filter
498 * @flags: flags to change filter behavior
499 * @filter: seccomp filter to add to the current process
500 *
501 * Caller must be holding current->sighand->siglock lock.
502 *
503 * Returns 0 on success, -ve on error.
504 */
505static long seccomp_attach_filter(unsigned int flags,
506 struct seccomp_filter *filter)
507{
508 unsigned long total_insns;
509 struct seccomp_filter *walker;
510
511 assert_spin_locked(&current->sighand->siglock);
512
513 /* Validate resulting filter length. */
514 total_insns = filter->prog->len;
515 for (walker = current->seccomp.filter; walker; walker = walker->prev)
516 total_insns += walker->prog->len + 4; /* 4 instr penalty */
517 if (total_insns > MAX_INSNS_PER_PATH)
518 return -ENOMEM;
519
520 /* If thread sync has been requested, check that it is possible. */
521 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
522 int ret;
523
524 ret = seccomp_can_sync_threads();
525 if (ret)
526 return ret;
527 }
528
529 /* Set log flag, if present. */
530 if (flags & SECCOMP_FILTER_FLAG_LOG)
531 filter->log = true;
532
533 /*
534 * If there is an existing filter, make it the prev and don't drop its
535 * task reference.
536 */
537 filter->prev = current->seccomp.filter;
538 current->seccomp.filter = filter;
539
540 /* Now that the new filter is in place, synchronize to all threads. */
541 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
542 seccomp_sync_threads(flags);
543
544 return 0;
545}
546
547static void __get_seccomp_filter(struct seccomp_filter *filter)
548{
549 refcount_inc(&filter->usage);
550}
551
552/* get_seccomp_filter - increments the reference count of the filter on @tsk */
553void get_seccomp_filter(struct task_struct *tsk)
554{
555 struct seccomp_filter *orig = tsk->seccomp.filter;
556 if (!orig)
557 return;
558 __get_seccomp_filter(orig);
559}
560
561static inline void seccomp_filter_free(struct seccomp_filter *filter)
562{
563 if (filter) {
564 bpf_prog_destroy(filter->prog);
565 kfree(filter);
566 }
567}
568
569static void __put_seccomp_filter(struct seccomp_filter *orig)
570{
571 /* Clean up single-reference branches iteratively. */
572 while (orig && refcount_dec_and_test(&orig->usage)) {
573 struct seccomp_filter *freeme = orig;
574 orig = orig->prev;
575 seccomp_filter_free(freeme);
576 }
577}
578
579/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
580void put_seccomp_filter(struct task_struct *tsk)
581{
582 __put_seccomp_filter(tsk->seccomp.filter);
583}
584
585static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
586{
587 clear_siginfo(info);
588 info->si_signo = SIGSYS;
589 info->si_code = SYS_SECCOMP;
590 info->si_call_addr = (void __user *)KSTK_EIP(current);
591 info->si_errno = reason;
592 info->si_arch = syscall_get_arch();
593 info->si_syscall = syscall;
594}
595
596/**
597 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
598 * @syscall: syscall number to send to userland
599 * @reason: filter-supplied reason code to send to userland (via si_errno)
600 *
601 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
602 */
603static void seccomp_send_sigsys(int syscall, int reason)
604{
605 struct kernel_siginfo info;
606 seccomp_init_siginfo(&info, syscall, reason);
607 force_sig_info(SIGSYS, &info, current);
608}
609#endif /* CONFIG_SECCOMP_FILTER */
610
611/* For use with seccomp_actions_logged */
612#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
613#define SECCOMP_LOG_KILL_THREAD (1 << 1)
614#define SECCOMP_LOG_TRAP (1 << 2)
615#define SECCOMP_LOG_ERRNO (1 << 3)
616#define SECCOMP_LOG_TRACE (1 << 4)
617#define SECCOMP_LOG_LOG (1 << 5)
618#define SECCOMP_LOG_ALLOW (1 << 6)
619#define SECCOMP_LOG_USER_NOTIF (1 << 7)
620
621static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
622 SECCOMP_LOG_KILL_THREAD |
623 SECCOMP_LOG_TRAP |
624 SECCOMP_LOG_ERRNO |
625 SECCOMP_LOG_USER_NOTIF |
626 SECCOMP_LOG_TRACE |
627 SECCOMP_LOG_LOG;
628
629static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
630 bool requested)
631{
632 bool log = false;
633
634 switch (action) {
635 case SECCOMP_RET_ALLOW:
636 break;
637 case SECCOMP_RET_TRAP:
638 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
639 break;
640 case SECCOMP_RET_ERRNO:
641 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
642 break;
643 case SECCOMP_RET_TRACE:
644 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
645 break;
646 case SECCOMP_RET_USER_NOTIF:
647 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
648 break;
649 case SECCOMP_RET_LOG:
650 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
651 break;
652 case SECCOMP_RET_KILL_THREAD:
653 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
654 break;
655 case SECCOMP_RET_KILL_PROCESS:
656 default:
657 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
658 }
659
660 /*
661 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
662 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
663 * any action from being logged by removing the action name from the
664 * seccomp_actions_logged sysctl.
665 */
666 if (!log)
667 return;
668
669 audit_seccomp(syscall, signr, action);
670}
671
672/*
673 * Secure computing mode 1 allows only read/write/exit/sigreturn.
674 * To be fully secure this must be combined with rlimit
675 * to limit the stack allocations too.
676 */
677static const int mode1_syscalls[] = {
678 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
679 0, /* null terminated */
680};
681
682static void __secure_computing_strict(int this_syscall)
683{
684 const int *syscall_whitelist = mode1_syscalls;
685#ifdef CONFIG_COMPAT
686 if (in_compat_syscall())
687 syscall_whitelist = get_compat_mode1_syscalls();
688#endif
689 do {
690 if (*syscall_whitelist == this_syscall)
691 return;
692 } while (*++syscall_whitelist);
693
694#ifdef SECCOMP_DEBUG
695 dump_stack();
696#endif
697 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
698 do_exit(SIGKILL);
699}
700
701#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
702void secure_computing_strict(int this_syscall)
703{
704 int mode = current->seccomp.mode;
705
706 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
707 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
708 return;
709
710 if (mode == SECCOMP_MODE_DISABLED)
711 return;
712 else if (mode == SECCOMP_MODE_STRICT)
713 __secure_computing_strict(this_syscall);
714 else
715 BUG();
716}
717#else
718
719#ifdef CONFIG_SECCOMP_FILTER
720static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
721{
722 /*
723 * Note: overflow is ok here, the id just needs to be unique per
724 * filter.
725 */
726 lockdep_assert_held(&filter->notify_lock);
727 return filter->notif->next_id++;
728}
729
730static void seccomp_do_user_notification(int this_syscall,
731 struct seccomp_filter *match,
732 const struct seccomp_data *sd)
733{
734 int err;
735 long ret = 0;
736 struct seccomp_knotif n = {};
737
738 mutex_lock(&match->notify_lock);
739 err = -ENOSYS;
740 if (!match->notif)
741 goto out;
742
743 n.task = current;
744 n.state = SECCOMP_NOTIFY_INIT;
745 n.data = sd;
746 n.id = seccomp_next_notify_id(match);
747 init_completion(&n.ready);
748 list_add(&n.list, &match->notif->notifications);
749
750 up(&match->notif->request);
751 wake_up_poll(&match->notif->wqh, EPOLLIN | EPOLLRDNORM);
752 mutex_unlock(&match->notify_lock);
753
754 /*
755 * This is where we wait for a reply from userspace.
756 */
757 err = wait_for_completion_interruptible(&n.ready);
758 mutex_lock(&match->notify_lock);
759 if (err == 0) {
760 ret = n.val;
761 err = n.error;
762 }
763
764 /*
765 * Note that it's possible the listener died in between the time when
766 * we were notified of a respons (or a signal) and when we were able to
767 * re-acquire the lock, so only delete from the list if the
768 * notification actually exists.
769 *
770 * Also note that this test is only valid because there's no way to
771 * *reattach* to a notifier right now. If one is added, we'll need to
772 * keep track of the notif itself and make sure they match here.
773 */
774 if (match->notif)
775 list_del(&n.list);
776out:
777 mutex_unlock(&match->notify_lock);
778 syscall_set_return_value(current, task_pt_regs(current),
779 err, ret);
780}
781
782static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
783 const bool recheck_after_trace)
784{
785 u32 filter_ret, action;
786 struct seccomp_filter *match = NULL;
787 int data;
788 struct seccomp_data sd_local;
789
790 /*
791 * Make sure that any changes to mode from another thread have
792 * been seen after TIF_SECCOMP was seen.
793 */
794 rmb();
795
796 if (!sd) {
797 populate_seccomp_data(&sd_local);
798 sd = &sd_local;
799 }
800
801 filter_ret = seccomp_run_filters(sd, &match);
802 data = filter_ret & SECCOMP_RET_DATA;
803 action = filter_ret & SECCOMP_RET_ACTION_FULL;
804
805 switch (action) {
806 case SECCOMP_RET_ERRNO:
807 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
808 if (data > MAX_ERRNO)
809 data = MAX_ERRNO;
810 syscall_set_return_value(current, task_pt_regs(current),
811 -data, 0);
812 goto skip;
813
814 case SECCOMP_RET_TRAP:
815 /* Show the handler the original registers. */
816 syscall_rollback(current, task_pt_regs(current));
817 /* Let the filter pass back 16 bits of data. */
818 seccomp_send_sigsys(this_syscall, data);
819 goto skip;
820
821 case SECCOMP_RET_TRACE:
822 /* We've been put in this state by the ptracer already. */
823 if (recheck_after_trace)
824 return 0;
825
826 /* ENOSYS these calls if there is no tracer attached. */
827 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
828 syscall_set_return_value(current,
829 task_pt_regs(current),
830 -ENOSYS, 0);
831 goto skip;
832 }
833
834 /* Allow the BPF to provide the event message */
835 ptrace_event(PTRACE_EVENT_SECCOMP, data);
836 /*
837 * The delivery of a fatal signal during event
838 * notification may silently skip tracer notification,
839 * which could leave us with a potentially unmodified
840 * syscall that the tracer would have liked to have
841 * changed. Since the process is about to die, we just
842 * force the syscall to be skipped and let the signal
843 * kill the process and correctly handle any tracer exit
844 * notifications.
845 */
846 if (fatal_signal_pending(current))
847 goto skip;
848 /* Check if the tracer forced the syscall to be skipped. */
849 this_syscall = syscall_get_nr(current, task_pt_regs(current));
850 if (this_syscall < 0)
851 goto skip;
852
853 /*
854 * Recheck the syscall, since it may have changed. This
855 * intentionally uses a NULL struct seccomp_data to force
856 * a reload of all registers. This does not goto skip since
857 * a skip would have already been reported.
858 */
859 if (__seccomp_filter(this_syscall, NULL, true))
860 return -1;
861
862 return 0;
863
864 case SECCOMP_RET_USER_NOTIF:
865 seccomp_do_user_notification(this_syscall, match, sd);
866 goto skip;
867
868 case SECCOMP_RET_LOG:
869 seccomp_log(this_syscall, 0, action, true);
870 return 0;
871
872 case SECCOMP_RET_ALLOW:
873 /*
874 * Note that the "match" filter will always be NULL for
875 * this action since SECCOMP_RET_ALLOW is the starting
876 * state in seccomp_run_filters().
877 */
878 return 0;
879
880 case SECCOMP_RET_KILL_THREAD:
881 case SECCOMP_RET_KILL_PROCESS:
882 default:
883 seccomp_log(this_syscall, SIGSYS, action, true);
884 /* Dump core only if this is the last remaining thread. */
885 if (action == SECCOMP_RET_KILL_PROCESS ||
886 get_nr_threads(current) == 1) {
887 kernel_siginfo_t info;
888
889 /* Show the original registers in the dump. */
890 syscall_rollback(current, task_pt_regs(current));
891 /* Trigger a manual coredump since do_exit skips it. */
892 seccomp_init_siginfo(&info, this_syscall, data);
893 do_coredump(&info);
894 }
895 if (action == SECCOMP_RET_KILL_PROCESS)
896 do_group_exit(SIGSYS);
897 else
898 do_exit(SIGSYS);
899 }
900
901 unreachable();
902
903skip:
904 seccomp_log(this_syscall, 0, action, match ? match->log : false);
905 return -1;
906}
907#else
908static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
909 const bool recheck_after_trace)
910{
911 BUG();
912}
913#endif
914
915int __secure_computing(const struct seccomp_data *sd)
916{
917 int mode = current->seccomp.mode;
918 int this_syscall;
919
920 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
921 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
922 return 0;
923
924 this_syscall = sd ? sd->nr :
925 syscall_get_nr(current, task_pt_regs(current));
926
927 switch (mode) {
928 case SECCOMP_MODE_STRICT:
929 __secure_computing_strict(this_syscall); /* may call do_exit */
930 return 0;
931 case SECCOMP_MODE_FILTER:
932 return __seccomp_filter(this_syscall, sd, false);
933 default:
934 BUG();
935 }
936}
937#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
938
939long prctl_get_seccomp(void)
940{
941 return current->seccomp.mode;
942}
943
944/**
945 * seccomp_set_mode_strict: internal function for setting strict seccomp
946 *
947 * Once current->seccomp.mode is non-zero, it may not be changed.
948 *
949 * Returns 0 on success or -EINVAL on failure.
950 */
951static long seccomp_set_mode_strict(void)
952{
953 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
954 long ret = -EINVAL;
955
956 spin_lock_irq(&current->sighand->siglock);
957
958 if (!seccomp_may_assign_mode(seccomp_mode))
959 goto out;
960
961#ifdef TIF_NOTSC
962 disable_TSC();
963#endif
964 seccomp_assign_mode(current, seccomp_mode, 0);
965 ret = 0;
966
967out:
968 spin_unlock_irq(&current->sighand->siglock);
969
970 return ret;
971}
972
973#ifdef CONFIG_SECCOMP_FILTER
974static int seccomp_notify_release(struct inode *inode, struct file *file)
975{
976 struct seccomp_filter *filter = file->private_data;
977 struct seccomp_knotif *knotif;
978
979 if (!filter)
980 return 0;
981
982 mutex_lock(&filter->notify_lock);
983
984 /*
985 * If this file is being closed because e.g. the task who owned it
986 * died, let's wake everyone up who was waiting on us.
987 */
988 list_for_each_entry(knotif, &filter->notif->notifications, list) {
989 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
990 continue;
991
992 knotif->state = SECCOMP_NOTIFY_REPLIED;
993 knotif->error = -ENOSYS;
994 knotif->val = 0;
995
996 complete(&knotif->ready);
997 }
998
999 kfree(filter->notif);
1000 filter->notif = NULL;
1001 mutex_unlock(&filter->notify_lock);
1002 __put_seccomp_filter(filter);
1003 return 0;
1004}
1005
1006static long seccomp_notify_recv(struct seccomp_filter *filter,
1007 void __user *buf)
1008{
1009 struct seccomp_knotif *knotif = NULL, *cur;
1010 struct seccomp_notif unotif;
1011 ssize_t ret;
1012
1013 memset(&unotif, 0, sizeof(unotif));
1014
1015 ret = down_interruptible(&filter->notif->request);
1016 if (ret < 0)
1017 return ret;
1018
1019 mutex_lock(&filter->notify_lock);
1020 list_for_each_entry(cur, &filter->notif->notifications, list) {
1021 if (cur->state == SECCOMP_NOTIFY_INIT) {
1022 knotif = cur;
1023 break;
1024 }
1025 }
1026
1027 /*
1028 * If we didn't find a notification, it could be that the task was
1029 * interrupted by a fatal signal between the time we were woken and
1030 * when we were able to acquire the rw lock.
1031 */
1032 if (!knotif) {
1033 ret = -ENOENT;
1034 goto out;
1035 }
1036
1037 unotif.id = knotif->id;
1038 unotif.pid = task_pid_vnr(knotif->task);
1039 unotif.data = *(knotif->data);
1040
1041 knotif->state = SECCOMP_NOTIFY_SENT;
1042 wake_up_poll(&filter->notif->wqh, EPOLLOUT | EPOLLWRNORM);
1043 ret = 0;
1044out:
1045 mutex_unlock(&filter->notify_lock);
1046
1047 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1048 ret = -EFAULT;
1049
1050 /*
1051 * Userspace screwed up. To make sure that we keep this
1052 * notification alive, let's reset it back to INIT. It
1053 * may have died when we released the lock, so we need to make
1054 * sure it's still around.
1055 */
1056 knotif = NULL;
1057 mutex_lock(&filter->notify_lock);
1058 list_for_each_entry(cur, &filter->notif->notifications, list) {
1059 if (cur->id == unotif.id) {
1060 knotif = cur;
1061 break;
1062 }
1063 }
1064
1065 if (knotif) {
1066 knotif->state = SECCOMP_NOTIFY_INIT;
1067 up(&filter->notif->request);
1068 }
1069 mutex_unlock(&filter->notify_lock);
1070 }
1071
1072 return ret;
1073}
1074
1075static long seccomp_notify_send(struct seccomp_filter *filter,
1076 void __user *buf)
1077{
1078 struct seccomp_notif_resp resp = {};
1079 struct seccomp_knotif *knotif = NULL, *cur;
1080 long ret;
1081
1082 if (copy_from_user(&resp, buf, sizeof(resp)))
1083 return -EFAULT;
1084
1085 if (resp.flags)
1086 return -EINVAL;
1087
1088 ret = mutex_lock_interruptible(&filter->notify_lock);
1089 if (ret < 0)
1090 return ret;
1091
1092 list_for_each_entry(cur, &filter->notif->notifications, list) {
1093 if (cur->id == resp.id) {
1094 knotif = cur;
1095 break;
1096 }
1097 }
1098
1099 if (!knotif) {
1100 ret = -ENOENT;
1101 goto out;
1102 }
1103
1104 /* Allow exactly one reply. */
1105 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1106 ret = -EINPROGRESS;
1107 goto out;
1108 }
1109
1110 ret = 0;
1111 knotif->state = SECCOMP_NOTIFY_REPLIED;
1112 knotif->error = resp.error;
1113 knotif->val = resp.val;
1114 complete(&knotif->ready);
1115out:
1116 mutex_unlock(&filter->notify_lock);
1117 return ret;
1118}
1119
1120static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1121 void __user *buf)
1122{
1123 struct seccomp_knotif *knotif = NULL;
1124 u64 id;
1125 long ret;
1126
1127 if (copy_from_user(&id, buf, sizeof(id)))
1128 return -EFAULT;
1129
1130 ret = mutex_lock_interruptible(&filter->notify_lock);
1131 if (ret < 0)
1132 return ret;
1133
1134 ret = -ENOENT;
1135 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1136 if (knotif->id == id) {
1137 if (knotif->state == SECCOMP_NOTIFY_SENT)
1138 ret = 0;
1139 goto out;
1140 }
1141 }
1142
1143out:
1144 mutex_unlock(&filter->notify_lock);
1145 return ret;
1146}
1147
1148static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1149 unsigned long arg)
1150{
1151 struct seccomp_filter *filter = file->private_data;
1152 void __user *buf = (void __user *)arg;
1153
1154 switch (cmd) {
1155 case SECCOMP_IOCTL_NOTIF_RECV:
1156 return seccomp_notify_recv(filter, buf);
1157 case SECCOMP_IOCTL_NOTIF_SEND:
1158 return seccomp_notify_send(filter, buf);
1159 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1160 return seccomp_notify_id_valid(filter, buf);
1161 default:
1162 return -EINVAL;
1163 }
1164}
1165
1166static __poll_t seccomp_notify_poll(struct file *file,
1167 struct poll_table_struct *poll_tab)
1168{
1169 struct seccomp_filter *filter = file->private_data;
1170 __poll_t ret = 0;
1171 struct seccomp_knotif *cur;
1172
1173 poll_wait(file, &filter->notif->wqh, poll_tab);
1174
1175 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1176 return EPOLLERR;
1177
1178 list_for_each_entry(cur, &filter->notif->notifications, list) {
1179 if (cur->state == SECCOMP_NOTIFY_INIT)
1180 ret |= EPOLLIN | EPOLLRDNORM;
1181 if (cur->state == SECCOMP_NOTIFY_SENT)
1182 ret |= EPOLLOUT | EPOLLWRNORM;
1183 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1184 break;
1185 }
1186
1187 mutex_unlock(&filter->notify_lock);
1188
1189 return ret;
1190}
1191
1192static const struct file_operations seccomp_notify_ops = {
1193 .poll = seccomp_notify_poll,
1194 .release = seccomp_notify_release,
1195 .unlocked_ioctl = seccomp_notify_ioctl,
1196};
1197
1198static struct file *init_listener(struct seccomp_filter *filter)
1199{
1200 struct file *ret = ERR_PTR(-EBUSY);
1201 struct seccomp_filter *cur;
1202
1203 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1204 if (cur->notif)
1205 goto out;
1206 }
1207
1208 ret = ERR_PTR(-ENOMEM);
1209 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1210 if (!filter->notif)
1211 goto out;
1212
1213 sema_init(&filter->notif->request, 0);
1214 filter->notif->next_id = get_random_u64();
1215 INIT_LIST_HEAD(&filter->notif->notifications);
1216 init_waitqueue_head(&filter->notif->wqh);
1217
1218 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1219 filter, O_RDWR);
1220 if (IS_ERR(ret))
1221 goto out_notif;
1222
1223 /* The file has a reference to it now */
1224 __get_seccomp_filter(filter);
1225
1226out_notif:
1227 if (IS_ERR(ret))
1228 kfree(filter->notif);
1229out:
1230 return ret;
1231}
1232
1233/**
1234 * seccomp_set_mode_filter: internal function for setting seccomp filter
1235 * @flags: flags to change filter behavior
1236 * @filter: struct sock_fprog containing filter
1237 *
1238 * This function may be called repeatedly to install additional filters.
1239 * Every filter successfully installed will be evaluated (in reverse order)
1240 * for each system call the task makes.
1241 *
1242 * Once current->seccomp.mode is non-zero, it may not be changed.
1243 *
1244 * Returns 0 on success or -EINVAL on failure.
1245 */
1246static long seccomp_set_mode_filter(unsigned int flags,
1247 const char __user *filter)
1248{
1249 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1250 struct seccomp_filter *prepared = NULL;
1251 long ret = -EINVAL;
1252 int listener = -1;
1253 struct file *listener_f = NULL;
1254
1255 /* Validate flags. */
1256 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1257 return -EINVAL;
1258
1259 /* Prepare the new filter before holding any locks. */
1260 prepared = seccomp_prepare_user_filter(filter);
1261 if (IS_ERR(prepared))
1262 return PTR_ERR(prepared);
1263
1264 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1265 listener = get_unused_fd_flags(O_CLOEXEC);
1266 if (listener < 0) {
1267 ret = listener;
1268 goto out_free;
1269 }
1270
1271 listener_f = init_listener(prepared);
1272 if (IS_ERR(listener_f)) {
1273 put_unused_fd(listener);
1274 ret = PTR_ERR(listener_f);
1275 goto out_free;
1276 }
1277 }
1278
1279 /*
1280 * Make sure we cannot change seccomp or nnp state via TSYNC
1281 * while another thread is in the middle of calling exec.
1282 */
1283 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1284 mutex_lock_killable(&current->signal->cred_guard_mutex))
1285 goto out_put_fd;
1286
1287 spin_lock_irq(&current->sighand->siglock);
1288
1289 if (!seccomp_may_assign_mode(seccomp_mode))
1290 goto out;
1291
1292 ret = seccomp_attach_filter(flags, prepared);
1293 if (ret)
1294 goto out;
1295 /* Do not free the successfully attached filter. */
1296 prepared = NULL;
1297
1298 seccomp_assign_mode(current, seccomp_mode, flags);
1299out:
1300 spin_unlock_irq(&current->sighand->siglock);
1301 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1302 mutex_unlock(&current->signal->cred_guard_mutex);
1303out_put_fd:
1304 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1305 if (ret < 0) {
1306 listener_f->private_data = NULL;
1307 fput(listener_f);
1308 put_unused_fd(listener);
1309 } else {
1310 fd_install(listener, listener_f);
1311 ret = listener;
1312 }
1313 }
1314out_free:
1315 seccomp_filter_free(prepared);
1316 return ret;
1317}
1318#else
1319static inline long seccomp_set_mode_filter(unsigned int flags,
1320 const char __user *filter)
1321{
1322 return -EINVAL;
1323}
1324#endif
1325
1326static long seccomp_get_action_avail(const char __user *uaction)
1327{
1328 u32 action;
1329
1330 if (copy_from_user(&action, uaction, sizeof(action)))
1331 return -EFAULT;
1332
1333 switch (action) {
1334 case SECCOMP_RET_KILL_PROCESS:
1335 case SECCOMP_RET_KILL_THREAD:
1336 case SECCOMP_RET_TRAP:
1337 case SECCOMP_RET_ERRNO:
1338 case SECCOMP_RET_USER_NOTIF:
1339 case SECCOMP_RET_TRACE:
1340 case SECCOMP_RET_LOG:
1341 case SECCOMP_RET_ALLOW:
1342 break;
1343 default:
1344 return -EOPNOTSUPP;
1345 }
1346
1347 return 0;
1348}
1349
1350static long seccomp_get_notif_sizes(void __user *usizes)
1351{
1352 struct seccomp_notif_sizes sizes = {
1353 .seccomp_notif = sizeof(struct seccomp_notif),
1354 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1355 .seccomp_data = sizeof(struct seccomp_data),
1356 };
1357
1358 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1359 return -EFAULT;
1360
1361 return 0;
1362}
1363
1364/* Common entry point for both prctl and syscall. */
1365static long do_seccomp(unsigned int op, unsigned int flags,
1366 void __user *uargs)
1367{
1368 switch (op) {
1369 case SECCOMP_SET_MODE_STRICT:
1370 if (flags != 0 || uargs != NULL)
1371 return -EINVAL;
1372 return seccomp_set_mode_strict();
1373 case SECCOMP_SET_MODE_FILTER:
1374 return seccomp_set_mode_filter(flags, uargs);
1375 case SECCOMP_GET_ACTION_AVAIL:
1376 if (flags != 0)
1377 return -EINVAL;
1378
1379 return seccomp_get_action_avail(uargs);
1380 case SECCOMP_GET_NOTIF_SIZES:
1381 if (flags != 0)
1382 return -EINVAL;
1383
1384 return seccomp_get_notif_sizes(uargs);
1385 default:
1386 return -EINVAL;
1387 }
1388}
1389
1390SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1391 void __user *, uargs)
1392{
1393 return do_seccomp(op, flags, uargs);
1394}
1395
1396/**
1397 * prctl_set_seccomp: configures current->seccomp.mode
1398 * @seccomp_mode: requested mode to use
1399 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1400 *
1401 * Returns 0 on success or -EINVAL on failure.
1402 */
1403long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1404{
1405 unsigned int op;
1406 void __user *uargs;
1407
1408 switch (seccomp_mode) {
1409 case SECCOMP_MODE_STRICT:
1410 op = SECCOMP_SET_MODE_STRICT;
1411 /*
1412 * Setting strict mode through prctl always ignored filter,
1413 * so make sure it is always NULL here to pass the internal
1414 * check in do_seccomp().
1415 */
1416 uargs = NULL;
1417 break;
1418 case SECCOMP_MODE_FILTER:
1419 op = SECCOMP_SET_MODE_FILTER;
1420 uargs = filter;
1421 break;
1422 default:
1423 return -EINVAL;
1424 }
1425
1426 /* prctl interface doesn't have flags, so they are always zero. */
1427 return do_seccomp(op, 0, uargs);
1428}
1429
1430#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1431static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1432 unsigned long filter_off)
1433{
1434 struct seccomp_filter *orig, *filter;
1435 unsigned long count;
1436
1437 /*
1438 * Note: this is only correct because the caller should be the (ptrace)
1439 * tracer of the task, otherwise lock_task_sighand is needed.
1440 */
1441 spin_lock_irq(&task->sighand->siglock);
1442
1443 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
1444 spin_unlock_irq(&task->sighand->siglock);
1445 return ERR_PTR(-EINVAL);
1446 }
1447
1448 orig = task->seccomp.filter;
1449 __get_seccomp_filter(orig);
1450 spin_unlock_irq(&task->sighand->siglock);
1451
1452 count = 0;
1453 for (filter = orig; filter; filter = filter->prev)
1454 count++;
1455
1456 if (filter_off >= count) {
1457 filter = ERR_PTR(-ENOENT);
1458 goto out;
1459 }
1460
1461 count -= filter_off;
1462 for (filter = orig; filter && count > 1; filter = filter->prev)
1463 count--;
1464
1465 if (WARN_ON(count != 1 || !filter)) {
1466 filter = ERR_PTR(-ENOENT);
1467 goto out;
1468 }
1469
1470 __get_seccomp_filter(filter);
1471
1472out:
1473 __put_seccomp_filter(orig);
1474 return filter;
1475}
1476
1477long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
1478 void __user *data)
1479{
1480 struct seccomp_filter *filter;
1481 struct sock_fprog_kern *fprog;
1482 long ret;
1483
1484 if (!capable(CAP_SYS_ADMIN) ||
1485 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1486 return -EACCES;
1487 }
1488
1489 filter = get_nth_filter(task, filter_off);
1490 if (IS_ERR(filter))
1491 return PTR_ERR(filter);
1492
1493 fprog = filter->prog->orig_prog;
1494 if (!fprog) {
1495 /* This must be a new non-cBPF filter, since we save
1496 * every cBPF filter's orig_prog above when
1497 * CONFIG_CHECKPOINT_RESTORE is enabled.
1498 */
1499 ret = -EMEDIUMTYPE;
1500 goto out;
1501 }
1502
1503 ret = fprog->len;
1504 if (!data)
1505 goto out;
1506
1507 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
1508 ret = -EFAULT;
1509
1510out:
1511 __put_seccomp_filter(filter);
1512 return ret;
1513}
1514
1515long seccomp_get_metadata(struct task_struct *task,
1516 unsigned long size, void __user *data)
1517{
1518 long ret;
1519 struct seccomp_filter *filter;
1520 struct seccomp_metadata kmd = {};
1521
1522 if (!capable(CAP_SYS_ADMIN) ||
1523 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1524 return -EACCES;
1525 }
1526
1527 size = min_t(unsigned long, size, sizeof(kmd));
1528
1529 if (size < sizeof(kmd.filter_off))
1530 return -EINVAL;
1531
1532 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
1533 return -EFAULT;
1534
1535 filter = get_nth_filter(task, kmd.filter_off);
1536 if (IS_ERR(filter))
1537 return PTR_ERR(filter);
1538
1539 if (filter->log)
1540 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
1541
1542 ret = size;
1543 if (copy_to_user(data, &kmd, size))
1544 ret = -EFAULT;
1545
1546 __put_seccomp_filter(filter);
1547 return ret;
1548}
1549#endif
1550
1551#ifdef CONFIG_SYSCTL
1552
1553/* Human readable action names for friendly sysctl interaction */
1554#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
1555#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
1556#define SECCOMP_RET_TRAP_NAME "trap"
1557#define SECCOMP_RET_ERRNO_NAME "errno"
1558#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
1559#define SECCOMP_RET_TRACE_NAME "trace"
1560#define SECCOMP_RET_LOG_NAME "log"
1561#define SECCOMP_RET_ALLOW_NAME "allow"
1562
1563static const char seccomp_actions_avail[] =
1564 SECCOMP_RET_KILL_PROCESS_NAME " "
1565 SECCOMP_RET_KILL_THREAD_NAME " "
1566 SECCOMP_RET_TRAP_NAME " "
1567 SECCOMP_RET_ERRNO_NAME " "
1568 SECCOMP_RET_USER_NOTIF_NAME " "
1569 SECCOMP_RET_TRACE_NAME " "
1570 SECCOMP_RET_LOG_NAME " "
1571 SECCOMP_RET_ALLOW_NAME;
1572
1573struct seccomp_log_name {
1574 u32 log;
1575 const char *name;
1576};
1577
1578static const struct seccomp_log_name seccomp_log_names[] = {
1579 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
1580 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
1581 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
1582 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
1583 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
1584 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
1585 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
1586 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
1587 { }
1588};
1589
1590static bool seccomp_names_from_actions_logged(char *names, size_t size,
1591 u32 actions_logged,
1592 const char *sep)
1593{
1594 const struct seccomp_log_name *cur;
1595 bool append_sep = false;
1596
1597 for (cur = seccomp_log_names; cur->name && size; cur++) {
1598 ssize_t ret;
1599
1600 if (!(actions_logged & cur->log))
1601 continue;
1602
1603 if (append_sep) {
1604 ret = strscpy(names, sep, size);
1605 if (ret < 0)
1606 return false;
1607
1608 names += ret;
1609 size -= ret;
1610 } else
1611 append_sep = true;
1612
1613 ret = strscpy(names, cur->name, size);
1614 if (ret < 0)
1615 return false;
1616
1617 names += ret;
1618 size -= ret;
1619 }
1620
1621 return true;
1622}
1623
1624static bool seccomp_action_logged_from_name(u32 *action_logged,
1625 const char *name)
1626{
1627 const struct seccomp_log_name *cur;
1628
1629 for (cur = seccomp_log_names; cur->name; cur++) {
1630 if (!strcmp(cur->name, name)) {
1631 *action_logged = cur->log;
1632 return true;
1633 }
1634 }
1635
1636 return false;
1637}
1638
1639static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
1640{
1641 char *name;
1642
1643 *actions_logged = 0;
1644 while ((name = strsep(&names, " ")) && *name) {
1645 u32 action_logged = 0;
1646
1647 if (!seccomp_action_logged_from_name(&action_logged, name))
1648 return false;
1649
1650 *actions_logged |= action_logged;
1651 }
1652
1653 return true;
1654}
1655
1656static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1657 size_t *lenp, loff_t *ppos)
1658{
1659 char names[sizeof(seccomp_actions_avail)];
1660 struct ctl_table table;
1661
1662 memset(names, 0, sizeof(names));
1663
1664 if (!seccomp_names_from_actions_logged(names, sizeof(names),
1665 seccomp_actions_logged, " "))
1666 return -EINVAL;
1667
1668 table = *ro_table;
1669 table.data = names;
1670 table.maxlen = sizeof(names);
1671 return proc_dostring(&table, 0, buffer, lenp, ppos);
1672}
1673
1674static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1675 size_t *lenp, loff_t *ppos, u32 *actions_logged)
1676{
1677 char names[sizeof(seccomp_actions_avail)];
1678 struct ctl_table table;
1679 int ret;
1680
1681 if (!capable(CAP_SYS_ADMIN))
1682 return -EPERM;
1683
1684 memset(names, 0, sizeof(names));
1685
1686 table = *ro_table;
1687 table.data = names;
1688 table.maxlen = sizeof(names);
1689 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
1690 if (ret)
1691 return ret;
1692
1693 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
1694 return -EINVAL;
1695
1696 if (*actions_logged & SECCOMP_LOG_ALLOW)
1697 return -EINVAL;
1698
1699 seccomp_actions_logged = *actions_logged;
1700 return 0;
1701}
1702
1703static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
1704 int ret)
1705{
1706 char names[sizeof(seccomp_actions_avail)];
1707 char old_names[sizeof(seccomp_actions_avail)];
1708 const char *new = names;
1709 const char *old = old_names;
1710
1711 if (!audit_enabled)
1712 return;
1713
1714 memset(names, 0, sizeof(names));
1715 memset(old_names, 0, sizeof(old_names));
1716
1717 if (ret)
1718 new = "?";
1719 else if (!actions_logged)
1720 new = "(none)";
1721 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
1722 actions_logged, ","))
1723 new = "?";
1724
1725 if (!old_actions_logged)
1726 old = "(none)";
1727 else if (!seccomp_names_from_actions_logged(old_names,
1728 sizeof(old_names),
1729 old_actions_logged, ","))
1730 old = "?";
1731
1732 return audit_seccomp_actions_logged(new, old, !ret);
1733}
1734
1735static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
1736 void __user *buffer, size_t *lenp,
1737 loff_t *ppos)
1738{
1739 int ret;
1740
1741 if (write) {
1742 u32 actions_logged = 0;
1743 u32 old_actions_logged = seccomp_actions_logged;
1744
1745 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
1746 &actions_logged);
1747 audit_actions_logged(actions_logged, old_actions_logged, ret);
1748 } else
1749 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
1750
1751 return ret;
1752}
1753
1754static struct ctl_path seccomp_sysctl_path[] = {
1755 { .procname = "kernel", },
1756 { .procname = "seccomp", },
1757 { }
1758};
1759
1760static struct ctl_table seccomp_sysctl_table[] = {
1761 {
1762 .procname = "actions_avail",
1763 .data = (void *) &seccomp_actions_avail,
1764 .maxlen = sizeof(seccomp_actions_avail),
1765 .mode = 0444,
1766 .proc_handler = proc_dostring,
1767 },
1768 {
1769 .procname = "actions_logged",
1770 .mode = 0644,
1771 .proc_handler = seccomp_actions_logged_handler,
1772 },
1773 { }
1774};
1775
1776static int __init seccomp_sysctl_init(void)
1777{
1778 struct ctl_table_header *hdr;
1779
1780 hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
1781 if (!hdr)
1782 pr_warn("seccomp: sysctl registration failed\n");
1783 else
1784 kmemleak_not_leak(hdr);
1785
1786 return 0;
1787}
1788
1789device_initcall(seccomp_sysctl_init)
1790
1791#endif /* CONFIG_SYSCTL */