1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/kernel/seccomp.c
4 *
5 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 *
7 * Copyright (C) 2012 Google, Inc.
8 * Will Drewry <wad@chromium.org>
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 preempt_disable();
271 for (; f; f = f->prev) {
272 u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
273
274 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
275 ret = cur_ret;
276 *match = f;
277 }
278 }
279 preempt_enable();
280 return ret;
281}
282#endif /* CONFIG_SECCOMP_FILTER */
283
284static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
285{
286 assert_spin_locked(&current->sighand->siglock);
287
288 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
289 return false;
290
291 return true;
292}
293
294void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
295
296static inline void seccomp_assign_mode(struct task_struct *task,
297 unsigned long seccomp_mode,
298 unsigned long flags)
299{
300 assert_spin_locked(&task->sighand->siglock);
301
302 task->seccomp.mode = seccomp_mode;
303 /*
304 * Make sure TIF_SECCOMP cannot be set before the mode (and
305 * filter) is set.
306 */
307 smp_mb__before_atomic();
308 /* Assume default seccomp processes want spec flaw mitigation. */
309 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
310 arch_seccomp_spec_mitigate(task);
311 set_tsk_thread_flag(task, TIF_SECCOMP);
312}
313
314#ifdef CONFIG_SECCOMP_FILTER
315/* Returns 1 if the parent is an ancestor of the child. */
316static int is_ancestor(struct seccomp_filter *parent,
317 struct seccomp_filter *child)
318{
319 /* NULL is the root ancestor. */
320 if (parent == NULL)
321 return 1;
322 for (; child; child = child->prev)
323 if (child == parent)
324 return 1;
325 return 0;
326}
327
328/**
329 * seccomp_can_sync_threads: checks if all threads can be synchronized
330 *
331 * Expects sighand and cred_guard_mutex locks to be held.
332 *
333 * Returns 0 on success, -ve on error, or the pid of a thread which was
334 * either not in the correct seccomp mode or it did not have an ancestral
335 * seccomp filter.
336 */
337static inline pid_t seccomp_can_sync_threads(void)
338{
339 struct task_struct *thread, *caller;
340
341 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
342 assert_spin_locked(&current->sighand->siglock);
343
344 /* Validate all threads being eligible for synchronization. */
345 caller = current;
346 for_each_thread(caller, thread) {
347 pid_t failed;
348
349 /* Skip current, since it is initiating the sync. */
350 if (thread == caller)
351 continue;
352
353 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
354 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
355 is_ancestor(thread->seccomp.filter,
356 caller->seccomp.filter)))
357 continue;
358
359 /* Return the first thread that cannot be synchronized. */
360 failed = task_pid_vnr(thread);
361 /* If the pid cannot be resolved, then return -ESRCH */
362 if (WARN_ON(failed == 0))
363 failed = -ESRCH;
364 return failed;
365 }
366
367 return 0;
368}
369
370/**
371 * seccomp_sync_threads: sets all threads to use current's filter
372 *
373 * Expects sighand and cred_guard_mutex locks to be held, and for
374 * seccomp_can_sync_threads() to have returned success already
375 * without dropping the locks.
376 *
377 */
378static inline void seccomp_sync_threads(unsigned long flags)
379{
380 struct task_struct *thread, *caller;
381
382 BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
383 assert_spin_locked(&current->sighand->siglock);
384
385 /* Synchronize all threads. */
386 caller = current;
387 for_each_thread(caller, thread) {
388 /* Skip current, since it needs no changes. */
389 if (thread == caller)
390 continue;
391
392 /* Get a task reference for the new leaf node. */
393 get_seccomp_filter(caller);
394 /*
395 * Drop the task reference to the shared ancestor since
396 * current's path will hold a reference. (This also
397 * allows a put before the assignment.)
398 */
399 put_seccomp_filter(thread);
400 smp_store_release(&thread->seccomp.filter,
401 caller->seccomp.filter);
402
403 /*
404 * Don't let an unprivileged task work around
405 * the no_new_privs restriction by creating
406 * a thread that sets it up, enters seccomp,
407 * then dies.
408 */
409 if (task_no_new_privs(caller))
410 task_set_no_new_privs(thread);
411
412 /*
413 * Opt the other thread into seccomp if needed.
414 * As threads are considered to be trust-realm
415 * equivalent (see ptrace_may_access), it is safe to
416 * allow one thread to transition the other.
417 */
418 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
419 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
420 flags);
421 }
422}
423
424/**
425 * seccomp_prepare_filter: Prepares a seccomp filter for use.
426 * @fprog: BPF program to install
427 *
428 * Returns filter on success or an ERR_PTR on failure.
429 */
430static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
431{
432 struct seccomp_filter *sfilter;
433 int ret;
434 const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
435
436 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
437 return ERR_PTR(-EINVAL);
438
439 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
440
441 /*
442 * Installing a seccomp filter requires that the task has
443 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
444 * This avoids scenarios where unprivileged tasks can affect the
445 * behavior of privileged children.
446 */
447 if (!task_no_new_privs(current) &&
448 security_capable(current_cred(), current_user_ns(),
449 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0)
450 return ERR_PTR(-EACCES);
451
452 /* Allocate a new seccomp_filter */
453 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
454 if (!sfilter)
455 return ERR_PTR(-ENOMEM);
456
457 mutex_init(&sfilter->notify_lock);
458 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
459 seccomp_check_filter, save_orig);
460 if (ret < 0) {
461 kfree(sfilter);
462 return ERR_PTR(ret);
463 }
464
465 refcount_set(&sfilter->usage, 1);
466
467 return sfilter;
468}
469
470/**
471 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
472 * @user_filter: pointer to the user data containing a sock_fprog.
473 *
474 * Returns 0 on success and non-zero otherwise.
475 */
476static struct seccomp_filter *
477seccomp_prepare_user_filter(const char __user *user_filter)
478{
479 struct sock_fprog fprog;
480 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
481
482#ifdef CONFIG_COMPAT
483 if (in_compat_syscall()) {
484 struct compat_sock_fprog fprog32;
485 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
486 goto out;
487 fprog.len = fprog32.len;
488 fprog.filter = compat_ptr(fprog32.filter);
489 } else /* falls through to the if below. */
490#endif
491 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
492 goto out;
493 filter = seccomp_prepare_filter(&fprog);
494out:
495 return filter;
496}
497
498/**
499 * seccomp_attach_filter: validate and attach filter
500 * @flags: flags to change filter behavior
501 * @filter: seccomp filter to add to the current process
502 *
503 * Caller must be holding current->sighand->siglock lock.
504 *
505 * Returns 0 on success, -ve on error.
506 */
507static long seccomp_attach_filter(unsigned int flags,
508 struct seccomp_filter *filter)
509{
510 unsigned long total_insns;
511 struct seccomp_filter *walker;
512
513 assert_spin_locked(&current->sighand->siglock);
514
515 /* Validate resulting filter length. */
516 total_insns = filter->prog->len;
517 for (walker = current->seccomp.filter; walker; walker = walker->prev)
518 total_insns += walker->prog->len + 4; /* 4 instr penalty */
519 if (total_insns > MAX_INSNS_PER_PATH)
520 return -ENOMEM;
521
522 /* If thread sync has been requested, check that it is possible. */
523 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
524 int ret;
525
526 ret = seccomp_can_sync_threads();
527 if (ret)
528 return ret;
529 }
530
531 /* Set log flag, if present. */
532 if (flags & SECCOMP_FILTER_FLAG_LOG)
533 filter->log = true;
534
535 /*
536 * If there is an existing filter, make it the prev and don't drop its
537 * task reference.
538 */
539 filter->prev = current->seccomp.filter;
540 current->seccomp.filter = filter;
541
542 /* Now that the new filter is in place, synchronize to all threads. */
543 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
544 seccomp_sync_threads(flags);
545
546 return 0;
547}
548
549static void __get_seccomp_filter(struct seccomp_filter *filter)
550{
551 refcount_inc(&filter->usage);
552}
553
554/* get_seccomp_filter - increments the reference count of the filter on @tsk */
555void get_seccomp_filter(struct task_struct *tsk)
556{
557 struct seccomp_filter *orig = tsk->seccomp.filter;
558 if (!orig)
559 return;
560 __get_seccomp_filter(orig);
561}
562
563static inline void seccomp_filter_free(struct seccomp_filter *filter)
564{
565 if (filter) {
566 bpf_prog_destroy(filter->prog);
567 kfree(filter);
568 }
569}
570
571static void __put_seccomp_filter(struct seccomp_filter *orig)
572{
573 /* Clean up single-reference branches iteratively. */
574 while (orig && refcount_dec_and_test(&orig->usage)) {
575 struct seccomp_filter *freeme = orig;
576 orig = orig->prev;
577 seccomp_filter_free(freeme);
578 }
579}
580
581/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
582void put_seccomp_filter(struct task_struct *tsk)
583{
584 __put_seccomp_filter(tsk->seccomp.filter);
585}
586
587static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
588{
589 clear_siginfo(info);
590 info->si_signo = SIGSYS;
591 info->si_code = SYS_SECCOMP;
592 info->si_call_addr = (void __user *)KSTK_EIP(current);
593 info->si_errno = reason;
594 info->si_arch = syscall_get_arch();
595 info->si_syscall = syscall;
596}
597
598/**
599 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
600 * @syscall: syscall number to send to userland
601 * @reason: filter-supplied reason code to send to userland (via si_errno)
602 *
603 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
604 */
605static void seccomp_send_sigsys(int syscall, int reason)
606{
607 struct kernel_siginfo info;
608 seccomp_init_siginfo(&info, syscall, reason);
609 force_sig_info(SIGSYS, &info, current);
610}
611#endif /* CONFIG_SECCOMP_FILTER */
612
613/* For use with seccomp_actions_logged */
614#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
615#define SECCOMP_LOG_KILL_THREAD (1 << 1)
616#define SECCOMP_LOG_TRAP (1 << 2)
617#define SECCOMP_LOG_ERRNO (1 << 3)
618#define SECCOMP_LOG_TRACE (1 << 4)
619#define SECCOMP_LOG_LOG (1 << 5)
620#define SECCOMP_LOG_ALLOW (1 << 6)
621#define SECCOMP_LOG_USER_NOTIF (1 << 7)
622
623static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
624 SECCOMP_LOG_KILL_THREAD |
625 SECCOMP_LOG_TRAP |
626 SECCOMP_LOG_ERRNO |
627 SECCOMP_LOG_USER_NOTIF |
628 SECCOMP_LOG_TRACE |
629 SECCOMP_LOG_LOG;
630
631static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
632 bool requested)
633{
634 bool log = false;
635
636 switch (action) {
637 case SECCOMP_RET_ALLOW:
638 break;
639 case SECCOMP_RET_TRAP:
640 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
641 break;
642 case SECCOMP_RET_ERRNO:
643 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
644 break;
645 case SECCOMP_RET_TRACE:
646 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
647 break;
648 case SECCOMP_RET_USER_NOTIF:
649 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
650 break;
651 case SECCOMP_RET_LOG:
652 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
653 break;
654 case SECCOMP_RET_KILL_THREAD:
655 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
656 break;
657 case SECCOMP_RET_KILL_PROCESS:
658 default:
659 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
660 }
661
662 /*
663 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
664 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
665 * any action from being logged by removing the action name from the
666 * seccomp_actions_logged sysctl.
667 */
668 if (!log)
669 return;
670
671 audit_seccomp(syscall, signr, action);
672}
673
674/*
675 * Secure computing mode 1 allows only read/write/exit/sigreturn.
676 * To be fully secure this must be combined with rlimit
677 * to limit the stack allocations too.
678 */
679static const int mode1_syscalls[] = {
680 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
681 0, /* null terminated */
682};
683
684static void __secure_computing_strict(int this_syscall)
685{
686 const int *syscall_whitelist = mode1_syscalls;
687#ifdef CONFIG_COMPAT
688 if (in_compat_syscall())
689 syscall_whitelist = get_compat_mode1_syscalls();
690#endif
691 do {
692 if (*syscall_whitelist == this_syscall)
693 return;
694 } while (*++syscall_whitelist);
695
696#ifdef SECCOMP_DEBUG
697 dump_stack();
698#endif
699 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
700 do_exit(SIGKILL);
701}
702
703#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
704void secure_computing_strict(int this_syscall)
705{
706 int mode = current->seccomp.mode;
707
708 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
709 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
710 return;
711
712 if (mode == SECCOMP_MODE_DISABLED)
713 return;
714 else if (mode == SECCOMP_MODE_STRICT)
715 __secure_computing_strict(this_syscall);
716 else
717 BUG();
718}
719#else
720
721#ifdef CONFIG_SECCOMP_FILTER
722static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
723{
724 /*
725 * Note: overflow is ok here, the id just needs to be unique per
726 * filter.
727 */
728 lockdep_assert_held(&filter->notify_lock);
729 return filter->notif->next_id++;
730}
731
732static void seccomp_do_user_notification(int this_syscall,
733 struct seccomp_filter *match,
734 const struct seccomp_data *sd)
735{
736 int err;
737 long ret = 0;
738 struct seccomp_knotif n = {};
739
740 mutex_lock(&match->notify_lock);
741 err = -ENOSYS;
742 if (!match->notif)
743 goto out;
744
745 n.task = current;
746 n.state = SECCOMP_NOTIFY_INIT;
747 n.data = sd;
748 n.id = seccomp_next_notify_id(match);
749 init_completion(&n.ready);
750 list_add(&n.list, &match->notif->notifications);
751
752 up(&match->notif->request);
753 wake_up_poll(&match->notif->wqh, EPOLLIN | EPOLLRDNORM);
754 mutex_unlock(&match->notify_lock);
755
756 /*
757 * This is where we wait for a reply from userspace.
758 */
759 err = wait_for_completion_interruptible(&n.ready);
760 mutex_lock(&match->notify_lock);
761 if (err == 0) {
762 ret = n.val;
763 err = n.error;
764 }
765
766 /*
767 * Note that it's possible the listener died in between the time when
768 * we were notified of a respons (or a signal) and when we were able to
769 * re-acquire the lock, so only delete from the list if the
770 * notification actually exists.
771 *
772 * Also note that this test is only valid because there's no way to
773 * *reattach* to a notifier right now. If one is added, we'll need to
774 * keep track of the notif itself and make sure they match here.
775 */
776 if (match->notif)
777 list_del(&n.list);
778out:
779 mutex_unlock(&match->notify_lock);
780 syscall_set_return_value(current, task_pt_regs(current),
781 err, ret);
782}
783
784static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
785 const bool recheck_after_trace)
786{
787 u32 filter_ret, action;
788 struct seccomp_filter *match = NULL;
789 int data;
790 struct seccomp_data sd_local;
791
792 /*
793 * Make sure that any changes to mode from another thread have
794 * been seen after TIF_SECCOMP was seen.
795 */
796 rmb();
797
798 if (!sd) {
799 populate_seccomp_data(&sd_local);
800 sd = &sd_local;
801 }
802
803 filter_ret = seccomp_run_filters(sd, &match);
804 data = filter_ret & SECCOMP_RET_DATA;
805 action = filter_ret & SECCOMP_RET_ACTION_FULL;
806
807 switch (action) {
808 case SECCOMP_RET_ERRNO:
809 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
810 if (data > MAX_ERRNO)
811 data = MAX_ERRNO;
812 syscall_set_return_value(current, task_pt_regs(current),
813 -data, 0);
814 goto skip;
815
816 case SECCOMP_RET_TRAP:
817 /* Show the handler the original registers. */
818 syscall_rollback(current, task_pt_regs(current));
819 /* Let the filter pass back 16 bits of data. */
820 seccomp_send_sigsys(this_syscall, data);
821 goto skip;
822
823 case SECCOMP_RET_TRACE:
824 /* We've been put in this state by the ptracer already. */
825 if (recheck_after_trace)
826 return 0;
827
828 /* ENOSYS these calls if there is no tracer attached. */
829 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
830 syscall_set_return_value(current,
831 task_pt_regs(current),
832 -ENOSYS, 0);
833 goto skip;
834 }
835
836 /* Allow the BPF to provide the event message */
837 ptrace_event(PTRACE_EVENT_SECCOMP, data);
838 /*
839 * The delivery of a fatal signal during event
840 * notification may silently skip tracer notification,
841 * which could leave us with a potentially unmodified
842 * syscall that the tracer would have liked to have
843 * changed. Since the process is about to die, we just
844 * force the syscall to be skipped and let the signal
845 * kill the process and correctly handle any tracer exit
846 * notifications.
847 */
848 if (fatal_signal_pending(current))
849 goto skip;
850 /* Check if the tracer forced the syscall to be skipped. */
851 this_syscall = syscall_get_nr(current, task_pt_regs(current));
852 if (this_syscall < 0)
853 goto skip;
854
855 /*
856 * Recheck the syscall, since it may have changed. This
857 * intentionally uses a NULL struct seccomp_data to force
858 * a reload of all registers. This does not goto skip since
859 * a skip would have already been reported.
860 */
861 if (__seccomp_filter(this_syscall, NULL, true))
862 return -1;
863
864 return 0;
865
866 case SECCOMP_RET_USER_NOTIF:
867 seccomp_do_user_notification(this_syscall, match, sd);
868 goto skip;
869
870 case SECCOMP_RET_LOG:
871 seccomp_log(this_syscall, 0, action, true);
872 return 0;
873
874 case SECCOMP_RET_ALLOW:
875 /*
876 * Note that the "match" filter will always be NULL for
877 * this action since SECCOMP_RET_ALLOW is the starting
878 * state in seccomp_run_filters().
879 */
880 return 0;
881
882 case SECCOMP_RET_KILL_THREAD:
883 case SECCOMP_RET_KILL_PROCESS:
884 default:
885 seccomp_log(this_syscall, SIGSYS, action, true);
886 /* Dump core only if this is the last remaining thread. */
887 if (action == SECCOMP_RET_KILL_PROCESS ||
888 get_nr_threads(current) == 1) {
889 kernel_siginfo_t info;
890
891 /* Show the original registers in the dump. */
892 syscall_rollback(current, task_pt_regs(current));
893 /* Trigger a manual coredump since do_exit skips it. */
894 seccomp_init_siginfo(&info, this_syscall, data);
895 do_coredump(&info);
896 }
897 if (action == SECCOMP_RET_KILL_PROCESS)
898 do_group_exit(SIGSYS);
899 else
900 do_exit(SIGSYS);
901 }
902
903 unreachable();
904
905skip:
906 seccomp_log(this_syscall, 0, action, match ? match->log : false);
907 return -1;
908}
909#else
910static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
911 const bool recheck_after_trace)
912{
913 BUG();
914}
915#endif
916
917int __secure_computing(const struct seccomp_data *sd)
918{
919 int mode = current->seccomp.mode;
920 int this_syscall;
921
922 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
923 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
924 return 0;
925
926 this_syscall = sd ? sd->nr :
927 syscall_get_nr(current, task_pt_regs(current));
928
929 switch (mode) {
930 case SECCOMP_MODE_STRICT:
931 __secure_computing_strict(this_syscall); /* may call do_exit */
932 return 0;
933 case SECCOMP_MODE_FILTER:
934 return __seccomp_filter(this_syscall, sd, false);
935 default:
936 BUG();
937 }
938}
939#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
940
941long prctl_get_seccomp(void)
942{
943 return current->seccomp.mode;
944}
945
946/**
947 * seccomp_set_mode_strict: internal function for setting strict seccomp
948 *
949 * Once current->seccomp.mode is non-zero, it may not be changed.
950 *
951 * Returns 0 on success or -EINVAL on failure.
952 */
953static long seccomp_set_mode_strict(void)
954{
955 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
956 long ret = -EINVAL;
957
958 spin_lock_irq(&current->sighand->siglock);
959
960 if (!seccomp_may_assign_mode(seccomp_mode))
961 goto out;
962
963#ifdef TIF_NOTSC
964 disable_TSC();
965#endif
966 seccomp_assign_mode(current, seccomp_mode, 0);
967 ret = 0;
968
969out:
970 spin_unlock_irq(&current->sighand->siglock);
971
972 return ret;
973}
974
975#ifdef CONFIG_SECCOMP_FILTER
976static int seccomp_notify_release(struct inode *inode, struct file *file)
977{
978 struct seccomp_filter *filter = file->private_data;
979 struct seccomp_knotif *knotif;
980
981 if (!filter)
982 return 0;
983
984 mutex_lock(&filter->notify_lock);
985
986 /*
987 * If this file is being closed because e.g. the task who owned it
988 * died, let's wake everyone up who was waiting on us.
989 */
990 list_for_each_entry(knotif, &filter->notif->notifications, list) {
991 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
992 continue;
993
994 knotif->state = SECCOMP_NOTIFY_REPLIED;
995 knotif->error = -ENOSYS;
996 knotif->val = 0;
997
998 complete(&knotif->ready);
999 }
1000
1001 kfree(filter->notif);
1002 filter->notif = NULL;
1003 mutex_unlock(&filter->notify_lock);
1004 __put_seccomp_filter(filter);
1005 return 0;
1006}
1007
1008static long seccomp_notify_recv(struct seccomp_filter *filter,
1009 void __user *buf)
1010{
1011 struct seccomp_knotif *knotif = NULL, *cur;
1012 struct seccomp_notif unotif;
1013 ssize_t ret;
1014
1015 memset(&unotif, 0, sizeof(unotif));
1016
1017 ret = down_interruptible(&filter->notif->request);
1018 if (ret < 0)
1019 return ret;
1020
1021 mutex_lock(&filter->notify_lock);
1022 list_for_each_entry(cur, &filter->notif->notifications, list) {
1023 if (cur->state == SECCOMP_NOTIFY_INIT) {
1024 knotif = cur;
1025 break;
1026 }
1027 }
1028
1029 /*
1030 * If we didn't find a notification, it could be that the task was
1031 * interrupted by a fatal signal between the time we were woken and
1032 * when we were able to acquire the rw lock.
1033 */
1034 if (!knotif) {
1035 ret = -ENOENT;
1036 goto out;
1037 }
1038
1039 unotif.id = knotif->id;
1040 unotif.pid = task_pid_vnr(knotif->task);
1041 unotif.data = *(knotif->data);
1042
1043 knotif->state = SECCOMP_NOTIFY_SENT;
1044 wake_up_poll(&filter->notif->wqh, EPOLLOUT | EPOLLWRNORM);
1045 ret = 0;
1046out:
1047 mutex_unlock(&filter->notify_lock);
1048
1049 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1050 ret = -EFAULT;
1051
1052 /*
1053 * Userspace screwed up. To make sure that we keep this
1054 * notification alive, let's reset it back to INIT. It
1055 * may have died when we released the lock, so we need to make
1056 * sure it's still around.
1057 */
1058 knotif = NULL;
1059 mutex_lock(&filter->notify_lock);
1060 list_for_each_entry(cur, &filter->notif->notifications, list) {
1061 if (cur->id == unotif.id) {
1062 knotif = cur;
1063 break;
1064 }
1065 }
1066
1067 if (knotif) {
1068 knotif->state = SECCOMP_NOTIFY_INIT;
1069 up(&filter->notif->request);
1070 }
1071 mutex_unlock(&filter->notify_lock);
1072 }
1073
1074 return ret;
1075}
1076
1077static long seccomp_notify_send(struct seccomp_filter *filter,
1078 void __user *buf)
1079{
1080 struct seccomp_notif_resp resp = {};
1081 struct seccomp_knotif *knotif = NULL, *cur;
1082 long ret;
1083
1084 if (copy_from_user(&resp, buf, sizeof(resp)))
1085 return -EFAULT;
1086
1087 if (resp.flags)
1088 return -EINVAL;
1089
1090 ret = mutex_lock_interruptible(&filter->notify_lock);
1091 if (ret < 0)
1092 return ret;
1093
1094 list_for_each_entry(cur, &filter->notif->notifications, list) {
1095 if (cur->id == resp.id) {
1096 knotif = cur;
1097 break;
1098 }
1099 }
1100
1101 if (!knotif) {
1102 ret = -ENOENT;
1103 goto out;
1104 }
1105
1106 /* Allow exactly one reply. */
1107 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1108 ret = -EINPROGRESS;
1109 goto out;
1110 }
1111
1112 ret = 0;
1113 knotif->state = SECCOMP_NOTIFY_REPLIED;
1114 knotif->error = resp.error;
1115 knotif->val = resp.val;
1116 complete(&knotif->ready);
1117out:
1118 mutex_unlock(&filter->notify_lock);
1119 return ret;
1120}
1121
1122static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1123 void __user *buf)
1124{
1125 struct seccomp_knotif *knotif = NULL;
1126 u64 id;
1127 long ret;
1128
1129 if (copy_from_user(&id, buf, sizeof(id)))
1130 return -EFAULT;
1131
1132 ret = mutex_lock_interruptible(&filter->notify_lock);
1133 if (ret < 0)
1134 return ret;
1135
1136 ret = -ENOENT;
1137 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1138 if (knotif->id == id) {
1139 if (knotif->state == SECCOMP_NOTIFY_SENT)
1140 ret = 0;
1141 goto out;
1142 }
1143 }
1144
1145out:
1146 mutex_unlock(&filter->notify_lock);
1147 return ret;
1148}
1149
1150static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1151 unsigned long arg)
1152{
1153 struct seccomp_filter *filter = file->private_data;
1154 void __user *buf = (void __user *)arg;
1155
1156 switch (cmd) {
1157 case SECCOMP_IOCTL_NOTIF_RECV:
1158 return seccomp_notify_recv(filter, buf);
1159 case SECCOMP_IOCTL_NOTIF_SEND:
1160 return seccomp_notify_send(filter, buf);
1161 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1162 return seccomp_notify_id_valid(filter, buf);
1163 default:
1164 return -EINVAL;
1165 }
1166}
1167
1168static __poll_t seccomp_notify_poll(struct file *file,
1169 struct poll_table_struct *poll_tab)
1170{
1171 struct seccomp_filter *filter = file->private_data;
1172 __poll_t ret = 0;
1173 struct seccomp_knotif *cur;
1174
1175 poll_wait(file, &filter->notif->wqh, poll_tab);
1176
1177 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1178 return EPOLLERR;
1179
1180 list_for_each_entry(cur, &filter->notif->notifications, list) {
1181 if (cur->state == SECCOMP_NOTIFY_INIT)
1182 ret |= EPOLLIN | EPOLLRDNORM;
1183 if (cur->state == SECCOMP_NOTIFY_SENT)
1184 ret |= EPOLLOUT | EPOLLWRNORM;
1185 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1186 break;
1187 }
1188
1189 mutex_unlock(&filter->notify_lock);
1190
1191 return ret;
1192}
1193
1194static const struct file_operations seccomp_notify_ops = {
1195 .poll = seccomp_notify_poll,
1196 .release = seccomp_notify_release,
1197 .unlocked_ioctl = seccomp_notify_ioctl,
1198};
1199
1200static struct file *init_listener(struct seccomp_filter *filter)
1201{
1202 struct file *ret = ERR_PTR(-EBUSY);
1203 struct seccomp_filter *cur;
1204
1205 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1206 if (cur->notif)
1207 goto out;
1208 }
1209
1210 ret = ERR_PTR(-ENOMEM);
1211 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1212 if (!filter->notif)
1213 goto out;
1214
1215 sema_init(&filter->notif->request, 0);
1216 filter->notif->next_id = get_random_u64();
1217 INIT_LIST_HEAD(&filter->notif->notifications);
1218 init_waitqueue_head(&filter->notif->wqh);
1219
1220 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1221 filter, O_RDWR);
1222 if (IS_ERR(ret))
1223 goto out_notif;
1224
1225 /* The file has a reference to it now */
1226 __get_seccomp_filter(filter);
1227
1228out_notif:
1229 if (IS_ERR(ret))
1230 kfree(filter->notif);
1231out:
1232 return ret;
1233}
1234
1235/**
1236 * seccomp_set_mode_filter: internal function for setting seccomp filter
1237 * @flags: flags to change filter behavior
1238 * @filter: struct sock_fprog containing filter
1239 *
1240 * This function may be called repeatedly to install additional filters.
1241 * Every filter successfully installed will be evaluated (in reverse order)
1242 * for each system call the task makes.
1243 *
1244 * Once current->seccomp.mode is non-zero, it may not be changed.
1245 *
1246 * Returns 0 on success or -EINVAL on failure.
1247 */
1248static long seccomp_set_mode_filter(unsigned int flags,
1249 const char __user *filter)
1250{
1251 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1252 struct seccomp_filter *prepared = NULL;
1253 long ret = -EINVAL;
1254 int listener = -1;
1255 struct file *listener_f = NULL;
1256
1257 /* Validate flags. */
1258 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1259 return -EINVAL;
1260
1261 /* Prepare the new filter before holding any locks. */
1262 prepared = seccomp_prepare_user_filter(filter);
1263 if (IS_ERR(prepared))
1264 return PTR_ERR(prepared);
1265
1266 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1267 listener = get_unused_fd_flags(O_CLOEXEC);
1268 if (listener < 0) {
1269 ret = listener;
1270 goto out_free;
1271 }
1272
1273 listener_f = init_listener(prepared);
1274 if (IS_ERR(listener_f)) {
1275 put_unused_fd(listener);
1276 ret = PTR_ERR(listener_f);
1277 goto out_free;
1278 }
1279 }
1280
1281 /*
1282 * Make sure we cannot change seccomp or nnp state via TSYNC
1283 * while another thread is in the middle of calling exec.
1284 */
1285 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1286 mutex_lock_killable(&current->signal->cred_guard_mutex))
1287 goto out_put_fd;
1288
1289 spin_lock_irq(&current->sighand->siglock);
1290
1291 if (!seccomp_may_assign_mode(seccomp_mode))
1292 goto out;
1293
1294 ret = seccomp_attach_filter(flags, prepared);
1295 if (ret)
1296 goto out;
1297 /* Do not free the successfully attached filter. */
1298 prepared = NULL;
1299
1300 seccomp_assign_mode(current, seccomp_mode, flags);
1301out:
1302 spin_unlock_irq(&current->sighand->siglock);
1303 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1304 mutex_unlock(&current->signal->cred_guard_mutex);
1305out_put_fd:
1306 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1307 if (ret < 0) {
1308 listener_f->private_data = NULL;
1309 fput(listener_f);
1310 put_unused_fd(listener);
1311 } else {
1312 fd_install(listener, listener_f);
1313 ret = listener;
1314 }
1315 }
1316out_free:
1317 seccomp_filter_free(prepared);
1318 return ret;
1319}
1320#else
1321static inline long seccomp_set_mode_filter(unsigned int flags,
1322 const char __user *filter)
1323{
1324 return -EINVAL;
1325}
1326#endif
1327
1328static long seccomp_get_action_avail(const char __user *uaction)
1329{
1330 u32 action;
1331
1332 if (copy_from_user(&action, uaction, sizeof(action)))
1333 return -EFAULT;
1334
1335 switch (action) {
1336 case SECCOMP_RET_KILL_PROCESS:
1337 case SECCOMP_RET_KILL_THREAD:
1338 case SECCOMP_RET_TRAP:
1339 case SECCOMP_RET_ERRNO:
1340 case SECCOMP_RET_USER_NOTIF:
1341 case SECCOMP_RET_TRACE:
1342 case SECCOMP_RET_LOG:
1343 case SECCOMP_RET_ALLOW:
1344 break;
1345 default:
1346 return -EOPNOTSUPP;
1347 }
1348
1349 return 0;
1350}
1351
1352static long seccomp_get_notif_sizes(void __user *usizes)
1353{
1354 struct seccomp_notif_sizes sizes = {
1355 .seccomp_notif = sizeof(struct seccomp_notif),
1356 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1357 .seccomp_data = sizeof(struct seccomp_data),
1358 };
1359
1360 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1361 return -EFAULT;
1362
1363 return 0;
1364}
1365
1366/* Common entry point for both prctl and syscall. */
1367static long do_seccomp(unsigned int op, unsigned int flags,
1368 void __user *uargs)
1369{
1370 switch (op) {
1371 case SECCOMP_SET_MODE_STRICT:
1372 if (flags != 0 || uargs != NULL)
1373 return -EINVAL;
1374 return seccomp_set_mode_strict();
1375 case SECCOMP_SET_MODE_FILTER:
1376 return seccomp_set_mode_filter(flags, uargs);
1377 case SECCOMP_GET_ACTION_AVAIL:
1378 if (flags != 0)
1379 return -EINVAL;
1380
1381 return seccomp_get_action_avail(uargs);
1382 case SECCOMP_GET_NOTIF_SIZES:
1383 if (flags != 0)
1384 return -EINVAL;
1385
1386 return seccomp_get_notif_sizes(uargs);
1387 default:
1388 return -EINVAL;
1389 }
1390}
1391
1392SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1393 void __user *, uargs)
1394{
1395 return do_seccomp(op, flags, uargs);
1396}
1397
1398/**
1399 * prctl_set_seccomp: configures current->seccomp.mode
1400 * @seccomp_mode: requested mode to use
1401 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1402 *
1403 * Returns 0 on success or -EINVAL on failure.
1404 */
1405long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1406{
1407 unsigned int op;
1408 void __user *uargs;
1409
1410 switch (seccomp_mode) {
1411 case SECCOMP_MODE_STRICT:
1412 op = SECCOMP_SET_MODE_STRICT;
1413 /*
1414 * Setting strict mode through prctl always ignored filter,
1415 * so make sure it is always NULL here to pass the internal
1416 * check in do_seccomp().
1417 */
1418 uargs = NULL;
1419 break;
1420 case SECCOMP_MODE_FILTER:
1421 op = SECCOMP_SET_MODE_FILTER;
1422 uargs = filter;
1423 break;
1424 default:
1425 return -EINVAL;
1426 }
1427
1428 /* prctl interface doesn't have flags, so they are always zero. */
1429 return do_seccomp(op, 0, uargs);
1430}
1431
1432#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1433static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1434 unsigned long filter_off)
1435{
1436 struct seccomp_filter *orig, *filter;
1437 unsigned long count;
1438
1439 /*
1440 * Note: this is only correct because the caller should be the (ptrace)
1441 * tracer of the task, otherwise lock_task_sighand is needed.
1442 */
1443 spin_lock_irq(&task->sighand->siglock);
1444
1445 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
1446 spin_unlock_irq(&task->sighand->siglock);
1447 return ERR_PTR(-EINVAL);
1448 }
1449
1450 orig = task->seccomp.filter;
1451 __get_seccomp_filter(orig);
1452 spin_unlock_irq(&task->sighand->siglock);
1453
1454 count = 0;
1455 for (filter = orig; filter; filter = filter->prev)
1456 count++;
1457
1458 if (filter_off >= count) {
1459 filter = ERR_PTR(-ENOENT);
1460 goto out;
1461 }
1462
1463 count -= filter_off;
1464 for (filter = orig; filter && count > 1; filter = filter->prev)
1465 count--;
1466
1467 if (WARN_ON(count != 1 || !filter)) {
1468 filter = ERR_PTR(-ENOENT);
1469 goto out;
1470 }
1471
1472 __get_seccomp_filter(filter);
1473
1474out:
1475 __put_seccomp_filter(orig);
1476 return filter;
1477}
1478
1479long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
1480 void __user *data)
1481{
1482 struct seccomp_filter *filter;
1483 struct sock_fprog_kern *fprog;
1484 long ret;
1485
1486 if (!capable(CAP_SYS_ADMIN) ||
1487 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1488 return -EACCES;
1489 }
1490
1491 filter = get_nth_filter(task, filter_off);
1492 if (IS_ERR(filter))
1493 return PTR_ERR(filter);
1494
1495 fprog = filter->prog->orig_prog;
1496 if (!fprog) {
1497 /* This must be a new non-cBPF filter, since we save
1498 * every cBPF filter's orig_prog above when
1499 * CONFIG_CHECKPOINT_RESTORE is enabled.
1500 */
1501 ret = -EMEDIUMTYPE;
1502 goto out;
1503 }
1504
1505 ret = fprog->len;
1506 if (!data)
1507 goto out;
1508
1509 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
1510 ret = -EFAULT;
1511
1512out:
1513 __put_seccomp_filter(filter);
1514 return ret;
1515}
1516
1517long seccomp_get_metadata(struct task_struct *task,
1518 unsigned long size, void __user *data)
1519{
1520 long ret;
1521 struct seccomp_filter *filter;
1522 struct seccomp_metadata kmd = {};
1523
1524 if (!capable(CAP_SYS_ADMIN) ||
1525 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1526 return -EACCES;
1527 }
1528
1529 size = min_t(unsigned long, size, sizeof(kmd));
1530
1531 if (size < sizeof(kmd.filter_off))
1532 return -EINVAL;
1533
1534 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
1535 return -EFAULT;
1536
1537 filter = get_nth_filter(task, kmd.filter_off);
1538 if (IS_ERR(filter))
1539 return PTR_ERR(filter);
1540
1541 if (filter->log)
1542 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
1543
1544 ret = size;
1545 if (copy_to_user(data, &kmd, size))
1546 ret = -EFAULT;
1547
1548 __put_seccomp_filter(filter);
1549 return ret;
1550}
1551#endif
1552
1553#ifdef CONFIG_SYSCTL
1554
1555/* Human readable action names for friendly sysctl interaction */
1556#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
1557#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
1558#define SECCOMP_RET_TRAP_NAME "trap"
1559#define SECCOMP_RET_ERRNO_NAME "errno"
1560#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
1561#define SECCOMP_RET_TRACE_NAME "trace"
1562#define SECCOMP_RET_LOG_NAME "log"
1563#define SECCOMP_RET_ALLOW_NAME "allow"
1564
1565static const char seccomp_actions_avail[] =
1566 SECCOMP_RET_KILL_PROCESS_NAME " "
1567 SECCOMP_RET_KILL_THREAD_NAME " "
1568 SECCOMP_RET_TRAP_NAME " "
1569 SECCOMP_RET_ERRNO_NAME " "
1570 SECCOMP_RET_USER_NOTIF_NAME " "
1571 SECCOMP_RET_TRACE_NAME " "
1572 SECCOMP_RET_LOG_NAME " "
1573 SECCOMP_RET_ALLOW_NAME;
1574
1575struct seccomp_log_name {
1576 u32 log;
1577 const char *name;
1578};
1579
1580static const struct seccomp_log_name seccomp_log_names[] = {
1581 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
1582 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
1583 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
1584 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
1585 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
1586 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
1587 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
1588 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
1589 { }
1590};
1591
1592static bool seccomp_names_from_actions_logged(char *names, size_t size,
1593 u32 actions_logged,
1594 const char *sep)
1595{
1596 const struct seccomp_log_name *cur;
1597 bool append_sep = false;
1598
1599 for (cur = seccomp_log_names; cur->name && size; cur++) {
1600 ssize_t ret;
1601
1602 if (!(actions_logged & cur->log))
1603 continue;
1604
1605 if (append_sep) {
1606 ret = strscpy(names, sep, size);
1607 if (ret < 0)
1608 return false;
1609
1610 names += ret;
1611 size -= ret;
1612 } else
1613 append_sep = true;
1614
1615 ret = strscpy(names, cur->name, size);
1616 if (ret < 0)
1617 return false;
1618
1619 names += ret;
1620 size -= ret;
1621 }
1622
1623 return true;
1624}
1625
1626static bool seccomp_action_logged_from_name(u32 *action_logged,
1627 const char *name)
1628{
1629 const struct seccomp_log_name *cur;
1630
1631 for (cur = seccomp_log_names; cur->name; cur++) {
1632 if (!strcmp(cur->name, name)) {
1633 *action_logged = cur->log;
1634 return true;
1635 }
1636 }
1637
1638 return false;
1639}
1640
1641static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
1642{
1643 char *name;
1644
1645 *actions_logged = 0;
1646 while ((name = strsep(&names, " ")) && *name) {
1647 u32 action_logged = 0;
1648
1649 if (!seccomp_action_logged_from_name(&action_logged, name))
1650 return false;
1651
1652 *actions_logged |= action_logged;
1653 }
1654
1655 return true;
1656}
1657
1658static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1659 size_t *lenp, loff_t *ppos)
1660{
1661 char names[sizeof(seccomp_actions_avail)];
1662 struct ctl_table table;
1663
1664 memset(names, 0, sizeof(names));
1665
1666 if (!seccomp_names_from_actions_logged(names, sizeof(names),
1667 seccomp_actions_logged, " "))
1668 return -EINVAL;
1669
1670 table = *ro_table;
1671 table.data = names;
1672 table.maxlen = sizeof(names);
1673 return proc_dostring(&table, 0, buffer, lenp, ppos);
1674}
1675
1676static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1677 size_t *lenp, loff_t *ppos, u32 *actions_logged)
1678{
1679 char names[sizeof(seccomp_actions_avail)];
1680 struct ctl_table table;
1681 int ret;
1682
1683 if (!capable(CAP_SYS_ADMIN))
1684 return -EPERM;
1685
1686 memset(names, 0, sizeof(names));
1687
1688 table = *ro_table;
1689 table.data = names;
1690 table.maxlen = sizeof(names);
1691 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
1692 if (ret)
1693 return ret;
1694
1695 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
1696 return -EINVAL;
1697
1698 if (*actions_logged & SECCOMP_LOG_ALLOW)
1699 return -EINVAL;
1700
1701 seccomp_actions_logged = *actions_logged;
1702 return 0;
1703}
1704
1705static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
1706 int ret)
1707{
1708 char names[sizeof(seccomp_actions_avail)];
1709 char old_names[sizeof(seccomp_actions_avail)];
1710 const char *new = names;
1711 const char *old = old_names;
1712
1713 if (!audit_enabled)
1714 return;
1715
1716 memset(names, 0, sizeof(names));
1717 memset(old_names, 0, sizeof(old_names));
1718
1719 if (ret)
1720 new = "?";
1721 else if (!actions_logged)
1722 new = "(none)";
1723 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
1724 actions_logged, ","))
1725 new = "?";
1726
1727 if (!old_actions_logged)
1728 old = "(none)";
1729 else if (!seccomp_names_from_actions_logged(old_names,
1730 sizeof(old_names),
1731 old_actions_logged, ","))
1732 old = "?";
1733
1734 return audit_seccomp_actions_logged(new, old, !ret);
1735}
1736
1737static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
1738 void __user *buffer, size_t *lenp,
1739 loff_t *ppos)
1740{
1741 int ret;
1742
1743 if (write) {
1744 u32 actions_logged = 0;
1745 u32 old_actions_logged = seccomp_actions_logged;
1746
1747 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
1748 &actions_logged);
1749 audit_actions_logged(actions_logged, old_actions_logged, ret);
1750 } else
1751 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
1752
1753 return ret;
1754}
1755
1756static struct ctl_path seccomp_sysctl_path[] = {
1757 { .procname = "kernel", },
1758 { .procname = "seccomp", },
1759 { }
1760};
1761
1762static struct ctl_table seccomp_sysctl_table[] = {
1763 {
1764 .procname = "actions_avail",
1765 .data = (void *) &seccomp_actions_avail,
1766 .maxlen = sizeof(seccomp_actions_avail),
1767 .mode = 0444,
1768 .proc_handler = proc_dostring,
1769 },
1770 {
1771 .procname = "actions_logged",
1772 .mode = 0644,
1773 .proc_handler = seccomp_actions_logged_handler,
1774 },
1775 { }
1776};
1777
1778static int __init seccomp_sysctl_init(void)
1779{
1780 struct ctl_table_header *hdr;
1781
1782 hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
1783 if (!hdr)
1784 pr_warn("seccomp: sysctl registration failed\n");
1785 else
1786 kmemleak_not_leak(hdr);
1787
1788 return 0;
1789}
1790
1791device_initcall(seccomp_sysctl_init)
1792
1793#endif /* CONFIG_SYSCTL */
1794