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1/*
2 * linux/kernel/seccomp.c
3 *
4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
5 *
6 * Copyright (C) 2012 Google, Inc.
7 * Will Drewry <wad@chromium.org>
8 *
9 * This defines a simple but solid secure-computing facility.
10 *
11 * Mode 1 uses a fixed list of allowed system calls.
12 * Mode 2 allows user-defined system call filters in the form
13 * of Berkeley Packet Filters/Linux Socket Filters.
14 */
15
16#include <linux/atomic.h>
17#include <linux/audit.h>
18#include <linux/compat.h>
19#include <linux/sched.h>
20#include <linux/seccomp.h>
21#include <linux/slab.h>
22#include <linux/syscalls.h>
23
24#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
25#include <asm/syscall.h>
26#endif
27
28#ifdef CONFIG_SECCOMP_FILTER
29#include <linux/filter.h>
30#include <linux/pid.h>
31#include <linux/ptrace.h>
32#include <linux/security.h>
33#include <linux/tracehook.h>
34#include <linux/uaccess.h>
35
36/**
37 * struct seccomp_filter - container for seccomp BPF programs
38 *
39 * @usage: reference count to manage the object lifetime.
40 * get/put helpers should be used when accessing an instance
41 * outside of a lifetime-guarded section. In general, this
42 * is only needed for handling filters shared across tasks.
43 * @prev: points to a previously installed, or inherited, filter
44 * @prog: the BPF program to evaluate
45 *
46 * seccomp_filter objects are organized in a tree linked via the @prev
47 * pointer. For any task, it appears to be a singly-linked list starting
48 * with current->seccomp.filter, the most recently attached or inherited filter.
49 * However, multiple filters may share a @prev node, by way of fork(), which
50 * results in a unidirectional tree existing in memory. This is similar to
51 * how namespaces work.
52 *
53 * seccomp_filter objects should never be modified after being attached
54 * to a task_struct (other than @usage).
55 */
56struct seccomp_filter {
57 atomic_t usage;
58 struct seccomp_filter *prev;
59 struct bpf_prog *prog;
60};
61
62/* Limit any path through the tree to 256KB worth of instructions. */
63#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
64
65/*
66 * Endianness is explicitly ignored and left for BPF program authors to manage
67 * as per the specific architecture.
68 */
69static void populate_seccomp_data(struct seccomp_data *sd)
70{
71 struct task_struct *task = current;
72 struct pt_regs *regs = task_pt_regs(task);
73 unsigned long args[6];
74
75 sd->nr = syscall_get_nr(task, regs);
76 sd->arch = syscall_get_arch();
77 syscall_get_arguments(task, regs, 0, 6, args);
78 sd->args[0] = args[0];
79 sd->args[1] = args[1];
80 sd->args[2] = args[2];
81 sd->args[3] = args[3];
82 sd->args[4] = args[4];
83 sd->args[5] = args[5];
84 sd->instruction_pointer = KSTK_EIP(task);
85}
86
87/**
88 * seccomp_check_filter - verify seccomp filter code
89 * @filter: filter to verify
90 * @flen: length of filter
91 *
92 * Takes a previously checked filter (by bpf_check_classic) and
93 * redirects all filter code that loads struct sk_buff data
94 * and related data through seccomp_bpf_load. It also
95 * enforces length and alignment checking of those loads.
96 *
97 * Returns 0 if the rule set is legal or -EINVAL if not.
98 */
99static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
100{
101 int pc;
102 for (pc = 0; pc < flen; pc++) {
103 struct sock_filter *ftest = &filter[pc];
104 u16 code = ftest->code;
105 u32 k = ftest->k;
106
107 switch (code) {
108 case BPF_LD | BPF_W | BPF_ABS:
109 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
110 /* 32-bit aligned and not out of bounds. */
111 if (k >= sizeof(struct seccomp_data) || k & 3)
112 return -EINVAL;
113 continue;
114 case BPF_LD | BPF_W | BPF_LEN:
115 ftest->code = BPF_LD | BPF_IMM;
116 ftest->k = sizeof(struct seccomp_data);
117 continue;
118 case BPF_LDX | BPF_W | BPF_LEN:
119 ftest->code = BPF_LDX | BPF_IMM;
120 ftest->k = sizeof(struct seccomp_data);
121 continue;
122 /* Explicitly include allowed calls. */
123 case BPF_RET | BPF_K:
124 case BPF_RET | BPF_A:
125 case BPF_ALU | BPF_ADD | BPF_K:
126 case BPF_ALU | BPF_ADD | BPF_X:
127 case BPF_ALU | BPF_SUB | BPF_K:
128 case BPF_ALU | BPF_SUB | BPF_X:
129 case BPF_ALU | BPF_MUL | BPF_K:
130 case BPF_ALU | BPF_MUL | BPF_X:
131 case BPF_ALU | BPF_DIV | BPF_K:
132 case BPF_ALU | BPF_DIV | BPF_X:
133 case BPF_ALU | BPF_AND | BPF_K:
134 case BPF_ALU | BPF_AND | BPF_X:
135 case BPF_ALU | BPF_OR | BPF_K:
136 case BPF_ALU | BPF_OR | BPF_X:
137 case BPF_ALU | BPF_XOR | BPF_K:
138 case BPF_ALU | BPF_XOR | BPF_X:
139 case BPF_ALU | BPF_LSH | BPF_K:
140 case BPF_ALU | BPF_LSH | BPF_X:
141 case BPF_ALU | BPF_RSH | BPF_K:
142 case BPF_ALU | BPF_RSH | BPF_X:
143 case BPF_ALU | BPF_NEG:
144 case BPF_LD | BPF_IMM:
145 case BPF_LDX | BPF_IMM:
146 case BPF_MISC | BPF_TAX:
147 case BPF_MISC | BPF_TXA:
148 case BPF_LD | BPF_MEM:
149 case BPF_LDX | BPF_MEM:
150 case BPF_ST:
151 case BPF_STX:
152 case BPF_JMP | BPF_JA:
153 case BPF_JMP | BPF_JEQ | BPF_K:
154 case BPF_JMP | BPF_JEQ | BPF_X:
155 case BPF_JMP | BPF_JGE | BPF_K:
156 case BPF_JMP | BPF_JGE | BPF_X:
157 case BPF_JMP | BPF_JGT | BPF_K:
158 case BPF_JMP | BPF_JGT | BPF_X:
159 case BPF_JMP | BPF_JSET | BPF_K:
160 case BPF_JMP | BPF_JSET | BPF_X:
161 continue;
162 default:
163 return -EINVAL;
164 }
165 }
166 return 0;
167}
168
169/**
170 * seccomp_run_filters - evaluates all seccomp filters against @sd
171 * @sd: optional seccomp data to be passed to filters
172 *
173 * Returns valid seccomp BPF response codes.
174 */
175static u32 seccomp_run_filters(const struct seccomp_data *sd)
176{
177 struct seccomp_data sd_local;
178 u32 ret = SECCOMP_RET_ALLOW;
179 /* Make sure cross-thread synced filter points somewhere sane. */
180 struct seccomp_filter *f =
181 lockless_dereference(current->seccomp.filter);
182
183 /* Ensure unexpected behavior doesn't result in failing open. */
184 if (unlikely(WARN_ON(f == NULL)))
185 return SECCOMP_RET_KILL;
186
187 if (!sd) {
188 populate_seccomp_data(&sd_local);
189 sd = &sd_local;
190 }
191
192 /*
193 * All filters in the list are evaluated and the lowest BPF return
194 * value always takes priority (ignoring the DATA).
195 */
196 for (; f; f = f->prev) {
197 u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
198
199 if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
200 ret = cur_ret;
201 }
202 return ret;
203}
204#endif /* CONFIG_SECCOMP_FILTER */
205
206static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
207{
208 assert_spin_locked(¤t->sighand->siglock);
209
210 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
211 return false;
212
213 return true;
214}
215
216static inline void seccomp_assign_mode(struct task_struct *task,
217 unsigned long seccomp_mode)
218{
219 assert_spin_locked(&task->sighand->siglock);
220
221 task->seccomp.mode = seccomp_mode;
222 /*
223 * Make sure TIF_SECCOMP cannot be set before the mode (and
224 * filter) is set.
225 */
226 smp_mb__before_atomic();
227 set_tsk_thread_flag(task, TIF_SECCOMP);
228}
229
230#ifdef CONFIG_SECCOMP_FILTER
231/* Returns 1 if the parent is an ancestor of the child. */
232static int is_ancestor(struct seccomp_filter *parent,
233 struct seccomp_filter *child)
234{
235 /* NULL is the root ancestor. */
236 if (parent == NULL)
237 return 1;
238 for (; child; child = child->prev)
239 if (child == parent)
240 return 1;
241 return 0;
242}
243
244/**
245 * seccomp_can_sync_threads: checks if all threads can be synchronized
246 *
247 * Expects sighand and cred_guard_mutex locks to be held.
248 *
249 * Returns 0 on success, -ve on error, or the pid of a thread which was
250 * either not in the correct seccomp mode or it did not have an ancestral
251 * seccomp filter.
252 */
253static inline pid_t seccomp_can_sync_threads(void)
254{
255 struct task_struct *thread, *caller;
256
257 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
258 assert_spin_locked(¤t->sighand->siglock);
259
260 /* Validate all threads being eligible for synchronization. */
261 caller = current;
262 for_each_thread(caller, thread) {
263 pid_t failed;
264
265 /* Skip current, since it is initiating the sync. */
266 if (thread == caller)
267 continue;
268
269 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
270 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
271 is_ancestor(thread->seccomp.filter,
272 caller->seccomp.filter)))
273 continue;
274
275 /* Return the first thread that cannot be synchronized. */
276 failed = task_pid_vnr(thread);
277 /* If the pid cannot be resolved, then return -ESRCH */
278 if (unlikely(WARN_ON(failed == 0)))
279 failed = -ESRCH;
280 return failed;
281 }
282
283 return 0;
284}
285
286/**
287 * seccomp_sync_threads: sets all threads to use current's filter
288 *
289 * Expects sighand and cred_guard_mutex locks to be held, and for
290 * seccomp_can_sync_threads() to have returned success already
291 * without dropping the locks.
292 *
293 */
294static inline void seccomp_sync_threads(void)
295{
296 struct task_struct *thread, *caller;
297
298 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
299 assert_spin_locked(¤t->sighand->siglock);
300
301 /* Synchronize all threads. */
302 caller = current;
303 for_each_thread(caller, thread) {
304 /* Skip current, since it needs no changes. */
305 if (thread == caller)
306 continue;
307
308 /* Get a task reference for the new leaf node. */
309 get_seccomp_filter(caller);
310 /*
311 * Drop the task reference to the shared ancestor since
312 * current's path will hold a reference. (This also
313 * allows a put before the assignment.)
314 */
315 put_seccomp_filter(thread);
316 smp_store_release(&thread->seccomp.filter,
317 caller->seccomp.filter);
318
319 /*
320 * Don't let an unprivileged task work around
321 * the no_new_privs restriction by creating
322 * a thread that sets it up, enters seccomp,
323 * then dies.
324 */
325 if (task_no_new_privs(caller))
326 task_set_no_new_privs(thread);
327
328 /*
329 * Opt the other thread into seccomp if needed.
330 * As threads are considered to be trust-realm
331 * equivalent (see ptrace_may_access), it is safe to
332 * allow one thread to transition the other.
333 */
334 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
335 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
336 }
337}
338
339/**
340 * seccomp_prepare_filter: Prepares a seccomp filter for use.
341 * @fprog: BPF program to install
342 *
343 * Returns filter on success or an ERR_PTR on failure.
344 */
345static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
346{
347 struct seccomp_filter *sfilter;
348 int ret;
349 const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
350
351 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
352 return ERR_PTR(-EINVAL);
353
354 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
355
356 /*
357 * Installing a seccomp filter requires that the task has
358 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
359 * This avoids scenarios where unprivileged tasks can affect the
360 * behavior of privileged children.
361 */
362 if (!task_no_new_privs(current) &&
363 security_capable_noaudit(current_cred(), current_user_ns(),
364 CAP_SYS_ADMIN) != 0)
365 return ERR_PTR(-EACCES);
366
367 /* Allocate a new seccomp_filter */
368 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
369 if (!sfilter)
370 return ERR_PTR(-ENOMEM);
371
372 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
373 seccomp_check_filter, save_orig);
374 if (ret < 0) {
375 kfree(sfilter);
376 return ERR_PTR(ret);
377 }
378
379 atomic_set(&sfilter->usage, 1);
380
381 return sfilter;
382}
383
384/**
385 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
386 * @user_filter: pointer to the user data containing a sock_fprog.
387 *
388 * Returns 0 on success and non-zero otherwise.
389 */
390static struct seccomp_filter *
391seccomp_prepare_user_filter(const char __user *user_filter)
392{
393 struct sock_fprog fprog;
394 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
395
396#ifdef CONFIG_COMPAT
397 if (in_compat_syscall()) {
398 struct compat_sock_fprog fprog32;
399 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
400 goto out;
401 fprog.len = fprog32.len;
402 fprog.filter = compat_ptr(fprog32.filter);
403 } else /* falls through to the if below. */
404#endif
405 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
406 goto out;
407 filter = seccomp_prepare_filter(&fprog);
408out:
409 return filter;
410}
411
412/**
413 * seccomp_attach_filter: validate and attach filter
414 * @flags: flags to change filter behavior
415 * @filter: seccomp filter to add to the current process
416 *
417 * Caller must be holding current->sighand->siglock lock.
418 *
419 * Returns 0 on success, -ve on error.
420 */
421static long seccomp_attach_filter(unsigned int flags,
422 struct seccomp_filter *filter)
423{
424 unsigned long total_insns;
425 struct seccomp_filter *walker;
426
427 assert_spin_locked(¤t->sighand->siglock);
428
429 /* Validate resulting filter length. */
430 total_insns = filter->prog->len;
431 for (walker = current->seccomp.filter; walker; walker = walker->prev)
432 total_insns += walker->prog->len + 4; /* 4 instr penalty */
433 if (total_insns > MAX_INSNS_PER_PATH)
434 return -ENOMEM;
435
436 /* If thread sync has been requested, check that it is possible. */
437 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
438 int ret;
439
440 ret = seccomp_can_sync_threads();
441 if (ret)
442 return ret;
443 }
444
445 /*
446 * If there is an existing filter, make it the prev and don't drop its
447 * task reference.
448 */
449 filter->prev = current->seccomp.filter;
450 current->seccomp.filter = filter;
451
452 /* Now that the new filter is in place, synchronize to all threads. */
453 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
454 seccomp_sync_threads();
455
456 return 0;
457}
458
459/* get_seccomp_filter - increments the reference count of the filter on @tsk */
460void get_seccomp_filter(struct task_struct *tsk)
461{
462 struct seccomp_filter *orig = tsk->seccomp.filter;
463 if (!orig)
464 return;
465 /* Reference count is bounded by the number of total processes. */
466 atomic_inc(&orig->usage);
467}
468
469static inline void seccomp_filter_free(struct seccomp_filter *filter)
470{
471 if (filter) {
472 bpf_prog_destroy(filter->prog);
473 kfree(filter);
474 }
475}
476
477/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
478void put_seccomp_filter(struct task_struct *tsk)
479{
480 struct seccomp_filter *orig = tsk->seccomp.filter;
481 /* Clean up single-reference branches iteratively. */
482 while (orig && atomic_dec_and_test(&orig->usage)) {
483 struct seccomp_filter *freeme = orig;
484 orig = orig->prev;
485 seccomp_filter_free(freeme);
486 }
487}
488
489/**
490 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
491 * @syscall: syscall number to send to userland
492 * @reason: filter-supplied reason code to send to userland (via si_errno)
493 *
494 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
495 */
496static void seccomp_send_sigsys(int syscall, int reason)
497{
498 struct siginfo info;
499 memset(&info, 0, sizeof(info));
500 info.si_signo = SIGSYS;
501 info.si_code = SYS_SECCOMP;
502 info.si_call_addr = (void __user *)KSTK_EIP(current);
503 info.si_errno = reason;
504 info.si_arch = syscall_get_arch();
505 info.si_syscall = syscall;
506 force_sig_info(SIGSYS, &info, current);
507}
508#endif /* CONFIG_SECCOMP_FILTER */
509
510/*
511 * Secure computing mode 1 allows only read/write/exit/sigreturn.
512 * To be fully secure this must be combined with rlimit
513 * to limit the stack allocations too.
514 */
515static const int mode1_syscalls[] = {
516 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
517 0, /* null terminated */
518};
519
520static void __secure_computing_strict(int this_syscall)
521{
522 const int *syscall_whitelist = mode1_syscalls;
523#ifdef CONFIG_COMPAT
524 if (in_compat_syscall())
525 syscall_whitelist = get_compat_mode1_syscalls();
526#endif
527 do {
528 if (*syscall_whitelist == this_syscall)
529 return;
530 } while (*++syscall_whitelist);
531
532#ifdef SECCOMP_DEBUG
533 dump_stack();
534#endif
535 audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL);
536 do_exit(SIGKILL);
537}
538
539#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
540void secure_computing_strict(int this_syscall)
541{
542 int mode = current->seccomp.mode;
543
544 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
545 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
546 return;
547
548 if (mode == SECCOMP_MODE_DISABLED)
549 return;
550 else if (mode == SECCOMP_MODE_STRICT)
551 __secure_computing_strict(this_syscall);
552 else
553 BUG();
554}
555#else
556
557#ifdef CONFIG_SECCOMP_FILTER
558static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
559 const bool recheck_after_trace)
560{
561 u32 filter_ret, action;
562 int data;
563
564 /*
565 * Make sure that any changes to mode from another thread have
566 * been seen after TIF_SECCOMP was seen.
567 */
568 rmb();
569
570 filter_ret = seccomp_run_filters(sd);
571 data = filter_ret & SECCOMP_RET_DATA;
572 action = filter_ret & SECCOMP_RET_ACTION;
573
574 switch (action) {
575 case SECCOMP_RET_ERRNO:
576 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
577 if (data > MAX_ERRNO)
578 data = MAX_ERRNO;
579 syscall_set_return_value(current, task_pt_regs(current),
580 -data, 0);
581 goto skip;
582
583 case SECCOMP_RET_TRAP:
584 /* Show the handler the original registers. */
585 syscall_rollback(current, task_pt_regs(current));
586 /* Let the filter pass back 16 bits of data. */
587 seccomp_send_sigsys(this_syscall, data);
588 goto skip;
589
590 case SECCOMP_RET_TRACE:
591 /* We've been put in this state by the ptracer already. */
592 if (recheck_after_trace)
593 return 0;
594
595 /* ENOSYS these calls if there is no tracer attached. */
596 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
597 syscall_set_return_value(current,
598 task_pt_regs(current),
599 -ENOSYS, 0);
600 goto skip;
601 }
602
603 /* Allow the BPF to provide the event message */
604 ptrace_event(PTRACE_EVENT_SECCOMP, data);
605 /*
606 * The delivery of a fatal signal during event
607 * notification may silently skip tracer notification,
608 * which could leave us with a potentially unmodified
609 * syscall that the tracer would have liked to have
610 * changed. Since the process is about to die, we just
611 * force the syscall to be skipped and let the signal
612 * kill the process and correctly handle any tracer exit
613 * notifications.
614 */
615 if (fatal_signal_pending(current))
616 goto skip;
617 /* Check if the tracer forced the syscall to be skipped. */
618 this_syscall = syscall_get_nr(current, task_pt_regs(current));
619 if (this_syscall < 0)
620 goto skip;
621
622 /*
623 * Recheck the syscall, since it may have changed. This
624 * intentionally uses a NULL struct seccomp_data to force
625 * a reload of all registers. This does not goto skip since
626 * a skip would have already been reported.
627 */
628 if (__seccomp_filter(this_syscall, NULL, true))
629 return -1;
630
631 return 0;
632
633 case SECCOMP_RET_ALLOW:
634 return 0;
635
636 case SECCOMP_RET_KILL:
637 default:
638 audit_seccomp(this_syscall, SIGSYS, action);
639 do_exit(SIGSYS);
640 }
641
642 unreachable();
643
644skip:
645 audit_seccomp(this_syscall, 0, action);
646 return -1;
647}
648#else
649static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
650 const bool recheck_after_trace)
651{
652 BUG();
653}
654#endif
655
656int __secure_computing(const struct seccomp_data *sd)
657{
658 int mode = current->seccomp.mode;
659 int this_syscall;
660
661 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
662 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
663 return 0;
664
665 this_syscall = sd ? sd->nr :
666 syscall_get_nr(current, task_pt_regs(current));
667
668 switch (mode) {
669 case SECCOMP_MODE_STRICT:
670 __secure_computing_strict(this_syscall); /* may call do_exit */
671 return 0;
672 case SECCOMP_MODE_FILTER:
673 return __seccomp_filter(this_syscall, sd, false);
674 default:
675 BUG();
676 }
677}
678#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
679
680long prctl_get_seccomp(void)
681{
682 return current->seccomp.mode;
683}
684
685/**
686 * seccomp_set_mode_strict: internal function for setting strict seccomp
687 *
688 * Once current->seccomp.mode is non-zero, it may not be changed.
689 *
690 * Returns 0 on success or -EINVAL on failure.
691 */
692static long seccomp_set_mode_strict(void)
693{
694 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
695 long ret = -EINVAL;
696
697 spin_lock_irq(¤t->sighand->siglock);
698
699 if (!seccomp_may_assign_mode(seccomp_mode))
700 goto out;
701
702#ifdef TIF_NOTSC
703 disable_TSC();
704#endif
705 seccomp_assign_mode(current, seccomp_mode);
706 ret = 0;
707
708out:
709 spin_unlock_irq(¤t->sighand->siglock);
710
711 return ret;
712}
713
714#ifdef CONFIG_SECCOMP_FILTER
715/**
716 * seccomp_set_mode_filter: internal function for setting seccomp filter
717 * @flags: flags to change filter behavior
718 * @filter: struct sock_fprog containing filter
719 *
720 * This function may be called repeatedly to install additional filters.
721 * Every filter successfully installed will be evaluated (in reverse order)
722 * for each system call the task makes.
723 *
724 * Once current->seccomp.mode is non-zero, it may not be changed.
725 *
726 * Returns 0 on success or -EINVAL on failure.
727 */
728static long seccomp_set_mode_filter(unsigned int flags,
729 const char __user *filter)
730{
731 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
732 struct seccomp_filter *prepared = NULL;
733 long ret = -EINVAL;
734
735 /* Validate flags. */
736 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
737 return -EINVAL;
738
739 /* Prepare the new filter before holding any locks. */
740 prepared = seccomp_prepare_user_filter(filter);
741 if (IS_ERR(prepared))
742 return PTR_ERR(prepared);
743
744 /*
745 * Make sure we cannot change seccomp or nnp state via TSYNC
746 * while another thread is in the middle of calling exec.
747 */
748 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
749 mutex_lock_killable(¤t->signal->cred_guard_mutex))
750 goto out_free;
751
752 spin_lock_irq(¤t->sighand->siglock);
753
754 if (!seccomp_may_assign_mode(seccomp_mode))
755 goto out;
756
757 ret = seccomp_attach_filter(flags, prepared);
758 if (ret)
759 goto out;
760 /* Do not free the successfully attached filter. */
761 prepared = NULL;
762
763 seccomp_assign_mode(current, seccomp_mode);
764out:
765 spin_unlock_irq(¤t->sighand->siglock);
766 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
767 mutex_unlock(¤t->signal->cred_guard_mutex);
768out_free:
769 seccomp_filter_free(prepared);
770 return ret;
771}
772#else
773static inline long seccomp_set_mode_filter(unsigned int flags,
774 const char __user *filter)
775{
776 return -EINVAL;
777}
778#endif
779
780/* Common entry point for both prctl and syscall. */
781static long do_seccomp(unsigned int op, unsigned int flags,
782 const char __user *uargs)
783{
784 switch (op) {
785 case SECCOMP_SET_MODE_STRICT:
786 if (flags != 0 || uargs != NULL)
787 return -EINVAL;
788 return seccomp_set_mode_strict();
789 case SECCOMP_SET_MODE_FILTER:
790 return seccomp_set_mode_filter(flags, uargs);
791 default:
792 return -EINVAL;
793 }
794}
795
796SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
797 const char __user *, uargs)
798{
799 return do_seccomp(op, flags, uargs);
800}
801
802/**
803 * prctl_set_seccomp: configures current->seccomp.mode
804 * @seccomp_mode: requested mode to use
805 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
806 *
807 * Returns 0 on success or -EINVAL on failure.
808 */
809long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
810{
811 unsigned int op;
812 char __user *uargs;
813
814 switch (seccomp_mode) {
815 case SECCOMP_MODE_STRICT:
816 op = SECCOMP_SET_MODE_STRICT;
817 /*
818 * Setting strict mode through prctl always ignored filter,
819 * so make sure it is always NULL here to pass the internal
820 * check in do_seccomp().
821 */
822 uargs = NULL;
823 break;
824 case SECCOMP_MODE_FILTER:
825 op = SECCOMP_SET_MODE_FILTER;
826 uargs = filter;
827 break;
828 default:
829 return -EINVAL;
830 }
831
832 /* prctl interface doesn't have flags, so they are always zero. */
833 return do_seccomp(op, 0, uargs);
834}
835
836#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
837long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
838 void __user *data)
839{
840 struct seccomp_filter *filter;
841 struct sock_fprog_kern *fprog;
842 long ret;
843 unsigned long count = 0;
844
845 if (!capable(CAP_SYS_ADMIN) ||
846 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
847 return -EACCES;
848 }
849
850 spin_lock_irq(&task->sighand->siglock);
851 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
852 ret = -EINVAL;
853 goto out;
854 }
855
856 filter = task->seccomp.filter;
857 while (filter) {
858 filter = filter->prev;
859 count++;
860 }
861
862 if (filter_off >= count) {
863 ret = -ENOENT;
864 goto out;
865 }
866 count -= filter_off;
867
868 filter = task->seccomp.filter;
869 while (filter && count > 1) {
870 filter = filter->prev;
871 count--;
872 }
873
874 if (WARN_ON(count != 1 || !filter)) {
875 /* The filter tree shouldn't shrink while we're using it. */
876 ret = -ENOENT;
877 goto out;
878 }
879
880 fprog = filter->prog->orig_prog;
881 if (!fprog) {
882 /* This must be a new non-cBPF filter, since we save
883 * every cBPF filter's orig_prog above when
884 * CONFIG_CHECKPOINT_RESTORE is enabled.
885 */
886 ret = -EMEDIUMTYPE;
887 goto out;
888 }
889
890 ret = fprog->len;
891 if (!data)
892 goto out;
893
894 get_seccomp_filter(task);
895 spin_unlock_irq(&task->sighand->siglock);
896
897 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
898 ret = -EFAULT;
899
900 put_seccomp_filter(task);
901 return ret;
902
903out:
904 spin_unlock_irq(&task->sighand->siglock);
905 return ret;
906}
907#endif
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#define pr_fmt(fmt) "seccomp: " fmt
17
18#include <linux/refcount.h>
19#include <linux/audit.h>
20#include <linux/compat.h>
21#include <linux/coredump.h>
22#include <linux/kmemleak.h>
23#include <linux/nospec.h>
24#include <linux/prctl.h>
25#include <linux/sched.h>
26#include <linux/sched/task_stack.h>
27#include <linux/seccomp.h>
28#include <linux/slab.h>
29#include <linux/syscalls.h>
30#include <linux/sysctl.h>
31
32#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
33#include <asm/syscall.h>
34#endif
35
36#ifdef CONFIG_SECCOMP_FILTER
37#include <linux/file.h>
38#include <linux/filter.h>
39#include <linux/pid.h>
40#include <linux/ptrace.h>
41#include <linux/security.h>
42#include <linux/tracehook.h>
43#include <linux/uaccess.h>
44#include <linux/anon_inodes.h>
45#include <linux/lockdep.h>
46
47/*
48 * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
49 * wrong direction flag in the ioctl number. This is the broken one,
50 * which the kernel needs to keep supporting until all userspaces stop
51 * using the wrong command number.
52 */
53#define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
54
55enum notify_state {
56 SECCOMP_NOTIFY_INIT,
57 SECCOMP_NOTIFY_SENT,
58 SECCOMP_NOTIFY_REPLIED,
59};
60
61struct seccomp_knotif {
62 /* The struct pid of the task whose filter triggered the notification */
63 struct task_struct *task;
64
65 /* The "cookie" for this request; this is unique for this filter. */
66 u64 id;
67
68 /*
69 * The seccomp data. This pointer is valid the entire time this
70 * notification is active, since it comes from __seccomp_filter which
71 * eclipses the entire lifecycle here.
72 */
73 const struct seccomp_data *data;
74
75 /*
76 * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
77 * struct seccomp_knotif is created and starts out in INIT. Once the
78 * handler reads the notification off of an FD, it transitions to SENT.
79 * If a signal is received the state transitions back to INIT and
80 * another message is sent. When the userspace handler replies, state
81 * transitions to REPLIED.
82 */
83 enum notify_state state;
84
85 /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
86 int error;
87 long val;
88 u32 flags;
89
90 /*
91 * Signals when this has changed states, such as the listener
92 * dying, a new seccomp addfd message, or changing to REPLIED
93 */
94 struct completion ready;
95
96 struct list_head list;
97
98 /* outstanding addfd requests */
99 struct list_head addfd;
100};
101
102/**
103 * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
104 *
105 * @file: A reference to the file to install in the other task
106 * @fd: The fd number to install it at. If the fd number is -1, it means the
107 * installing process should allocate the fd as normal.
108 * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
109 * is allowed.
110 * @ret: The return value of the installing process. It is set to the fd num
111 * upon success (>= 0).
112 * @completion: Indicates that the installing process has completed fd
113 * installation, or gone away (either due to successful
114 * reply, or signal)
115 *
116 */
117struct seccomp_kaddfd {
118 struct file *file;
119 int fd;
120 unsigned int flags;
121
122 /* To only be set on reply */
123 int ret;
124 struct completion completion;
125 struct list_head list;
126};
127
128/**
129 * struct notification - container for seccomp userspace notifications. Since
130 * most seccomp filters will not have notification listeners attached and this
131 * structure is fairly large, we store the notification-specific stuff in a
132 * separate structure.
133 *
134 * @request: A semaphore that users of this notification can wait on for
135 * changes. Actual reads and writes are still controlled with
136 * filter->notify_lock.
137 * @next_id: The id of the next request.
138 * @notifications: A list of struct seccomp_knotif elements.
139 */
140struct notification {
141 struct semaphore request;
142 u64 next_id;
143 struct list_head notifications;
144};
145
146/**
147 * struct seccomp_filter - container for seccomp BPF programs
148 *
149 * @refs: Reference count to manage the object lifetime.
150 * A filter's reference count is incremented for each directly
151 * attached task, once for the dependent filter, and if
152 * requested for the user notifier. When @refs reaches zero,
153 * the filter can be freed.
154 * @users: A filter's @users count is incremented for each directly
155 * attached task (filter installation, fork(), thread_sync),
156 * and once for the dependent filter (tracked in filter->prev).
157 * When it reaches zero it indicates that no direct or indirect
158 * users of that filter exist. No new tasks can get associated with
159 * this filter after reaching 0. The @users count is always smaller
160 * or equal to @refs. Hence, reaching 0 for @users does not mean
161 * the filter can be freed.
162 * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
163 * @prev: points to a previously installed, or inherited, filter
164 * @prog: the BPF program to evaluate
165 * @notif: the struct that holds all notification related information
166 * @notify_lock: A lock for all notification-related accesses.
167 * @wqh: A wait queue for poll if a notifier is in use.
168 *
169 * seccomp_filter objects are organized in a tree linked via the @prev
170 * pointer. For any task, it appears to be a singly-linked list starting
171 * with current->seccomp.filter, the most recently attached or inherited filter.
172 * However, multiple filters may share a @prev node, by way of fork(), which
173 * results in a unidirectional tree existing in memory. This is similar to
174 * how namespaces work.
175 *
176 * seccomp_filter objects should never be modified after being attached
177 * to a task_struct (other than @refs).
178 */
179struct seccomp_filter {
180 refcount_t refs;
181 refcount_t users;
182 bool log;
183 struct seccomp_filter *prev;
184 struct bpf_prog *prog;
185 struct notification *notif;
186 struct mutex notify_lock;
187 wait_queue_head_t wqh;
188};
189
190/* Limit any path through the tree to 256KB worth of instructions. */
191#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
192
193/*
194 * Endianness is explicitly ignored and left for BPF program authors to manage
195 * as per the specific architecture.
196 */
197static void populate_seccomp_data(struct seccomp_data *sd)
198{
199 struct task_struct *task = current;
200 struct pt_regs *regs = task_pt_regs(task);
201 unsigned long args[6];
202
203 sd->nr = syscall_get_nr(task, regs);
204 sd->arch = syscall_get_arch(task);
205 syscall_get_arguments(task, regs, args);
206 sd->args[0] = args[0];
207 sd->args[1] = args[1];
208 sd->args[2] = args[2];
209 sd->args[3] = args[3];
210 sd->args[4] = args[4];
211 sd->args[5] = args[5];
212 sd->instruction_pointer = KSTK_EIP(task);
213}
214
215/**
216 * seccomp_check_filter - verify seccomp filter code
217 * @filter: filter to verify
218 * @flen: length of filter
219 *
220 * Takes a previously checked filter (by bpf_check_classic) and
221 * redirects all filter code that loads struct sk_buff data
222 * and related data through seccomp_bpf_load. It also
223 * enforces length and alignment checking of those loads.
224 *
225 * Returns 0 if the rule set is legal or -EINVAL if not.
226 */
227static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
228{
229 int pc;
230 for (pc = 0; pc < flen; pc++) {
231 struct sock_filter *ftest = &filter[pc];
232 u16 code = ftest->code;
233 u32 k = ftest->k;
234
235 switch (code) {
236 case BPF_LD | BPF_W | BPF_ABS:
237 ftest->code = BPF_LDX | BPF_W | BPF_ABS;
238 /* 32-bit aligned and not out of bounds. */
239 if (k >= sizeof(struct seccomp_data) || k & 3)
240 return -EINVAL;
241 continue;
242 case BPF_LD | BPF_W | BPF_LEN:
243 ftest->code = BPF_LD | BPF_IMM;
244 ftest->k = sizeof(struct seccomp_data);
245 continue;
246 case BPF_LDX | BPF_W | BPF_LEN:
247 ftest->code = BPF_LDX | BPF_IMM;
248 ftest->k = sizeof(struct seccomp_data);
249 continue;
250 /* Explicitly include allowed calls. */
251 case BPF_RET | BPF_K:
252 case BPF_RET | BPF_A:
253 case BPF_ALU | BPF_ADD | BPF_K:
254 case BPF_ALU | BPF_ADD | BPF_X:
255 case BPF_ALU | BPF_SUB | BPF_K:
256 case BPF_ALU | BPF_SUB | BPF_X:
257 case BPF_ALU | BPF_MUL | BPF_K:
258 case BPF_ALU | BPF_MUL | BPF_X:
259 case BPF_ALU | BPF_DIV | BPF_K:
260 case BPF_ALU | BPF_DIV | BPF_X:
261 case BPF_ALU | BPF_AND | BPF_K:
262 case BPF_ALU | BPF_AND | BPF_X:
263 case BPF_ALU | BPF_OR | BPF_K:
264 case BPF_ALU | BPF_OR | BPF_X:
265 case BPF_ALU | BPF_XOR | BPF_K:
266 case BPF_ALU | BPF_XOR | BPF_X:
267 case BPF_ALU | BPF_LSH | BPF_K:
268 case BPF_ALU | BPF_LSH | BPF_X:
269 case BPF_ALU | BPF_RSH | BPF_K:
270 case BPF_ALU | BPF_RSH | BPF_X:
271 case BPF_ALU | BPF_NEG:
272 case BPF_LD | BPF_IMM:
273 case BPF_LDX | BPF_IMM:
274 case BPF_MISC | BPF_TAX:
275 case BPF_MISC | BPF_TXA:
276 case BPF_LD | BPF_MEM:
277 case BPF_LDX | BPF_MEM:
278 case BPF_ST:
279 case BPF_STX:
280 case BPF_JMP | BPF_JA:
281 case BPF_JMP | BPF_JEQ | BPF_K:
282 case BPF_JMP | BPF_JEQ | BPF_X:
283 case BPF_JMP | BPF_JGE | BPF_K:
284 case BPF_JMP | BPF_JGE | BPF_X:
285 case BPF_JMP | BPF_JGT | BPF_K:
286 case BPF_JMP | BPF_JGT | BPF_X:
287 case BPF_JMP | BPF_JSET | BPF_K:
288 case BPF_JMP | BPF_JSET | BPF_X:
289 continue;
290 default:
291 return -EINVAL;
292 }
293 }
294 return 0;
295}
296
297/**
298 * seccomp_run_filters - evaluates all seccomp filters against @sd
299 * @sd: optional seccomp data to be passed to filters
300 * @match: stores struct seccomp_filter that resulted in the return value,
301 * unless filter returned SECCOMP_RET_ALLOW, in which case it will
302 * be unchanged.
303 *
304 * Returns valid seccomp BPF response codes.
305 */
306#define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
307static u32 seccomp_run_filters(const struct seccomp_data *sd,
308 struct seccomp_filter **match)
309{
310 u32 ret = SECCOMP_RET_ALLOW;
311 /* Make sure cross-thread synced filter points somewhere sane. */
312 struct seccomp_filter *f =
313 READ_ONCE(current->seccomp.filter);
314
315 /* Ensure unexpected behavior doesn't result in failing open. */
316 if (WARN_ON(f == NULL))
317 return SECCOMP_RET_KILL_PROCESS;
318
319 /*
320 * All filters in the list are evaluated and the lowest BPF return
321 * value always takes priority (ignoring the DATA).
322 */
323 for (; f; f = f->prev) {
324 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
325
326 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
327 ret = cur_ret;
328 *match = f;
329 }
330 }
331 return ret;
332}
333#endif /* CONFIG_SECCOMP_FILTER */
334
335static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
336{
337 assert_spin_locked(¤t->sighand->siglock);
338
339 if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
340 return false;
341
342 return true;
343}
344
345void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
346
347static inline void seccomp_assign_mode(struct task_struct *task,
348 unsigned long seccomp_mode,
349 unsigned long flags)
350{
351 assert_spin_locked(&task->sighand->siglock);
352
353 task->seccomp.mode = seccomp_mode;
354 /*
355 * Make sure TIF_SECCOMP cannot be set before the mode (and
356 * filter) is set.
357 */
358 smp_mb__before_atomic();
359 /* Assume default seccomp processes want spec flaw mitigation. */
360 if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
361 arch_seccomp_spec_mitigate(task);
362 set_tsk_thread_flag(task, TIF_SECCOMP);
363}
364
365#ifdef CONFIG_SECCOMP_FILTER
366/* Returns 1 if the parent is an ancestor of the child. */
367static int is_ancestor(struct seccomp_filter *parent,
368 struct seccomp_filter *child)
369{
370 /* NULL is the root ancestor. */
371 if (parent == NULL)
372 return 1;
373 for (; child; child = child->prev)
374 if (child == parent)
375 return 1;
376 return 0;
377}
378
379/**
380 * seccomp_can_sync_threads: checks if all threads can be synchronized
381 *
382 * Expects sighand and cred_guard_mutex locks to be held.
383 *
384 * Returns 0 on success, -ve on error, or the pid of a thread which was
385 * either not in the correct seccomp mode or did not have an ancestral
386 * seccomp filter.
387 */
388static inline pid_t seccomp_can_sync_threads(void)
389{
390 struct task_struct *thread, *caller;
391
392 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
393 assert_spin_locked(¤t->sighand->siglock);
394
395 /* Validate all threads being eligible for synchronization. */
396 caller = current;
397 for_each_thread(caller, thread) {
398 pid_t failed;
399
400 /* Skip current, since it is initiating the sync. */
401 if (thread == caller)
402 continue;
403
404 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
405 (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
406 is_ancestor(thread->seccomp.filter,
407 caller->seccomp.filter)))
408 continue;
409
410 /* Return the first thread that cannot be synchronized. */
411 failed = task_pid_vnr(thread);
412 /* If the pid cannot be resolved, then return -ESRCH */
413 if (WARN_ON(failed == 0))
414 failed = -ESRCH;
415 return failed;
416 }
417
418 return 0;
419}
420
421static inline void seccomp_filter_free(struct seccomp_filter *filter)
422{
423 if (filter) {
424 bpf_prog_destroy(filter->prog);
425 kfree(filter);
426 }
427}
428
429static void __seccomp_filter_orphan(struct seccomp_filter *orig)
430{
431 while (orig && refcount_dec_and_test(&orig->users)) {
432 if (waitqueue_active(&orig->wqh))
433 wake_up_poll(&orig->wqh, EPOLLHUP);
434 orig = orig->prev;
435 }
436}
437
438static void __put_seccomp_filter(struct seccomp_filter *orig)
439{
440 /* Clean up single-reference branches iteratively. */
441 while (orig && refcount_dec_and_test(&orig->refs)) {
442 struct seccomp_filter *freeme = orig;
443 orig = orig->prev;
444 seccomp_filter_free(freeme);
445 }
446}
447
448static void __seccomp_filter_release(struct seccomp_filter *orig)
449{
450 /* Notify about any unused filters in the task's former filter tree. */
451 __seccomp_filter_orphan(orig);
452 /* Finally drop all references to the task's former tree. */
453 __put_seccomp_filter(orig);
454}
455
456/**
457 * seccomp_filter_release - Detach the task from its filter tree,
458 * drop its reference count, and notify
459 * about unused filters
460 *
461 * This function should only be called when the task is exiting as
462 * it detaches it from its filter tree. As such, READ_ONCE() and
463 * barriers are not needed here, as would normally be needed.
464 */
465void seccomp_filter_release(struct task_struct *tsk)
466{
467 struct seccomp_filter *orig = tsk->seccomp.filter;
468
469 /* Detach task from its filter tree. */
470 tsk->seccomp.filter = NULL;
471 __seccomp_filter_release(orig);
472}
473
474/**
475 * seccomp_sync_threads: sets all threads to use current's filter
476 *
477 * Expects sighand and cred_guard_mutex locks to be held, and for
478 * seccomp_can_sync_threads() to have returned success already
479 * without dropping the locks.
480 *
481 */
482static inline void seccomp_sync_threads(unsigned long flags)
483{
484 struct task_struct *thread, *caller;
485
486 BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
487 assert_spin_locked(¤t->sighand->siglock);
488
489 /* Synchronize all threads. */
490 caller = current;
491 for_each_thread(caller, thread) {
492 /* Skip current, since it needs no changes. */
493 if (thread == caller)
494 continue;
495
496 /* Get a task reference for the new leaf node. */
497 get_seccomp_filter(caller);
498
499 /*
500 * Drop the task reference to the shared ancestor since
501 * current's path will hold a reference. (This also
502 * allows a put before the assignment.)
503 */
504 __seccomp_filter_release(thread->seccomp.filter);
505
506 /* Make our new filter tree visible. */
507 smp_store_release(&thread->seccomp.filter,
508 caller->seccomp.filter);
509 atomic_set(&thread->seccomp.filter_count,
510 atomic_read(&thread->seccomp.filter_count));
511
512 /*
513 * Don't let an unprivileged task work around
514 * the no_new_privs restriction by creating
515 * a thread that sets it up, enters seccomp,
516 * then dies.
517 */
518 if (task_no_new_privs(caller))
519 task_set_no_new_privs(thread);
520
521 /*
522 * Opt the other thread into seccomp if needed.
523 * As threads are considered to be trust-realm
524 * equivalent (see ptrace_may_access), it is safe to
525 * allow one thread to transition the other.
526 */
527 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
528 seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
529 flags);
530 }
531}
532
533/**
534 * seccomp_prepare_filter: Prepares a seccomp filter for use.
535 * @fprog: BPF program to install
536 *
537 * Returns filter on success or an ERR_PTR on failure.
538 */
539static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
540{
541 struct seccomp_filter *sfilter;
542 int ret;
543 const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
544
545 if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
546 return ERR_PTR(-EINVAL);
547
548 BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
549
550 /*
551 * Installing a seccomp filter requires that the task has
552 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
553 * This avoids scenarios where unprivileged tasks can affect the
554 * behavior of privileged children.
555 */
556 if (!task_no_new_privs(current) &&
557 security_capable(current_cred(), current_user_ns(),
558 CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0)
559 return ERR_PTR(-EACCES);
560
561 /* Allocate a new seccomp_filter */
562 sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
563 if (!sfilter)
564 return ERR_PTR(-ENOMEM);
565
566 mutex_init(&sfilter->notify_lock);
567 ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
568 seccomp_check_filter, save_orig);
569 if (ret < 0) {
570 kfree(sfilter);
571 return ERR_PTR(ret);
572 }
573
574 refcount_set(&sfilter->refs, 1);
575 refcount_set(&sfilter->users, 1);
576 init_waitqueue_head(&sfilter->wqh);
577
578 return sfilter;
579}
580
581/**
582 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
583 * @user_filter: pointer to the user data containing a sock_fprog.
584 *
585 * Returns 0 on success and non-zero otherwise.
586 */
587static struct seccomp_filter *
588seccomp_prepare_user_filter(const char __user *user_filter)
589{
590 struct sock_fprog fprog;
591 struct seccomp_filter *filter = ERR_PTR(-EFAULT);
592
593#ifdef CONFIG_COMPAT
594 if (in_compat_syscall()) {
595 struct compat_sock_fprog fprog32;
596 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
597 goto out;
598 fprog.len = fprog32.len;
599 fprog.filter = compat_ptr(fprog32.filter);
600 } else /* falls through to the if below. */
601#endif
602 if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
603 goto out;
604 filter = seccomp_prepare_filter(&fprog);
605out:
606 return filter;
607}
608
609/**
610 * seccomp_attach_filter: validate and attach filter
611 * @flags: flags to change filter behavior
612 * @filter: seccomp filter to add to the current process
613 *
614 * Caller must be holding current->sighand->siglock lock.
615 *
616 * Returns 0 on success, -ve on error, or
617 * - in TSYNC mode: the pid of a thread which was either not in the correct
618 * seccomp mode or did not have an ancestral seccomp filter
619 * - in NEW_LISTENER mode: the fd of the new listener
620 */
621static long seccomp_attach_filter(unsigned int flags,
622 struct seccomp_filter *filter)
623{
624 unsigned long total_insns;
625 struct seccomp_filter *walker;
626
627 assert_spin_locked(¤t->sighand->siglock);
628
629 /* Validate resulting filter length. */
630 total_insns = filter->prog->len;
631 for (walker = current->seccomp.filter; walker; walker = walker->prev)
632 total_insns += walker->prog->len + 4; /* 4 instr penalty */
633 if (total_insns > MAX_INSNS_PER_PATH)
634 return -ENOMEM;
635
636 /* If thread sync has been requested, check that it is possible. */
637 if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
638 int ret;
639
640 ret = seccomp_can_sync_threads();
641 if (ret) {
642 if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
643 return -ESRCH;
644 else
645 return ret;
646 }
647 }
648
649 /* Set log flag, if present. */
650 if (flags & SECCOMP_FILTER_FLAG_LOG)
651 filter->log = true;
652
653 /*
654 * If there is an existing filter, make it the prev and don't drop its
655 * task reference.
656 */
657 filter->prev = current->seccomp.filter;
658 current->seccomp.filter = filter;
659 atomic_inc(¤t->seccomp.filter_count);
660
661 /* Now that the new filter is in place, synchronize to all threads. */
662 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
663 seccomp_sync_threads(flags);
664
665 return 0;
666}
667
668static void __get_seccomp_filter(struct seccomp_filter *filter)
669{
670 refcount_inc(&filter->refs);
671}
672
673/* get_seccomp_filter - increments the reference count of the filter on @tsk */
674void get_seccomp_filter(struct task_struct *tsk)
675{
676 struct seccomp_filter *orig = tsk->seccomp.filter;
677 if (!orig)
678 return;
679 __get_seccomp_filter(orig);
680 refcount_inc(&orig->users);
681}
682
683static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
684{
685 clear_siginfo(info);
686 info->si_signo = SIGSYS;
687 info->si_code = SYS_SECCOMP;
688 info->si_call_addr = (void __user *)KSTK_EIP(current);
689 info->si_errno = reason;
690 info->si_arch = syscall_get_arch(current);
691 info->si_syscall = syscall;
692}
693
694/**
695 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
696 * @syscall: syscall number to send to userland
697 * @reason: filter-supplied reason code to send to userland (via si_errno)
698 *
699 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
700 */
701static void seccomp_send_sigsys(int syscall, int reason)
702{
703 struct kernel_siginfo info;
704 seccomp_init_siginfo(&info, syscall, reason);
705 force_sig_info(&info);
706}
707#endif /* CONFIG_SECCOMP_FILTER */
708
709/* For use with seccomp_actions_logged */
710#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
711#define SECCOMP_LOG_KILL_THREAD (1 << 1)
712#define SECCOMP_LOG_TRAP (1 << 2)
713#define SECCOMP_LOG_ERRNO (1 << 3)
714#define SECCOMP_LOG_TRACE (1 << 4)
715#define SECCOMP_LOG_LOG (1 << 5)
716#define SECCOMP_LOG_ALLOW (1 << 6)
717#define SECCOMP_LOG_USER_NOTIF (1 << 7)
718
719static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
720 SECCOMP_LOG_KILL_THREAD |
721 SECCOMP_LOG_TRAP |
722 SECCOMP_LOG_ERRNO |
723 SECCOMP_LOG_USER_NOTIF |
724 SECCOMP_LOG_TRACE |
725 SECCOMP_LOG_LOG;
726
727static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
728 bool requested)
729{
730 bool log = false;
731
732 switch (action) {
733 case SECCOMP_RET_ALLOW:
734 break;
735 case SECCOMP_RET_TRAP:
736 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
737 break;
738 case SECCOMP_RET_ERRNO:
739 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
740 break;
741 case SECCOMP_RET_TRACE:
742 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
743 break;
744 case SECCOMP_RET_USER_NOTIF:
745 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
746 break;
747 case SECCOMP_RET_LOG:
748 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
749 break;
750 case SECCOMP_RET_KILL_THREAD:
751 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
752 break;
753 case SECCOMP_RET_KILL_PROCESS:
754 default:
755 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
756 }
757
758 /*
759 * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
760 * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
761 * any action from being logged by removing the action name from the
762 * seccomp_actions_logged sysctl.
763 */
764 if (!log)
765 return;
766
767 audit_seccomp(syscall, signr, action);
768}
769
770/*
771 * Secure computing mode 1 allows only read/write/exit/sigreturn.
772 * To be fully secure this must be combined with rlimit
773 * to limit the stack allocations too.
774 */
775static const int mode1_syscalls[] = {
776 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
777 -1, /* negative terminated */
778};
779
780static void __secure_computing_strict(int this_syscall)
781{
782 const int *allowed_syscalls = mode1_syscalls;
783#ifdef CONFIG_COMPAT
784 if (in_compat_syscall())
785 allowed_syscalls = get_compat_mode1_syscalls();
786#endif
787 do {
788 if (*allowed_syscalls == this_syscall)
789 return;
790 } while (*++allowed_syscalls != -1);
791
792#ifdef SECCOMP_DEBUG
793 dump_stack();
794#endif
795 seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
796 do_exit(SIGKILL);
797}
798
799#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
800void secure_computing_strict(int this_syscall)
801{
802 int mode = current->seccomp.mode;
803
804 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
805 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
806 return;
807
808 if (mode == SECCOMP_MODE_DISABLED)
809 return;
810 else if (mode == SECCOMP_MODE_STRICT)
811 __secure_computing_strict(this_syscall);
812 else
813 BUG();
814}
815#else
816
817#ifdef CONFIG_SECCOMP_FILTER
818static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
819{
820 /*
821 * Note: overflow is ok here, the id just needs to be unique per
822 * filter.
823 */
824 lockdep_assert_held(&filter->notify_lock);
825 return filter->notif->next_id++;
826}
827
828static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
829{
830 /*
831 * Remove the notification, and reset the list pointers, indicating
832 * that it has been handled.
833 */
834 list_del_init(&addfd->list);
835 addfd->ret = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
836 complete(&addfd->completion);
837}
838
839static int seccomp_do_user_notification(int this_syscall,
840 struct seccomp_filter *match,
841 const struct seccomp_data *sd)
842{
843 int err;
844 u32 flags = 0;
845 long ret = 0;
846 struct seccomp_knotif n = {};
847 struct seccomp_kaddfd *addfd, *tmp;
848
849 mutex_lock(&match->notify_lock);
850 err = -ENOSYS;
851 if (!match->notif)
852 goto out;
853
854 n.task = current;
855 n.state = SECCOMP_NOTIFY_INIT;
856 n.data = sd;
857 n.id = seccomp_next_notify_id(match);
858 init_completion(&n.ready);
859 list_add(&n.list, &match->notif->notifications);
860 INIT_LIST_HEAD(&n.addfd);
861
862 up(&match->notif->request);
863 wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
864 mutex_unlock(&match->notify_lock);
865
866 /*
867 * This is where we wait for a reply from userspace.
868 */
869wait:
870 err = wait_for_completion_interruptible(&n.ready);
871 mutex_lock(&match->notify_lock);
872 if (err == 0) {
873 /* Check if we were woken up by a addfd message */
874 addfd = list_first_entry_or_null(&n.addfd,
875 struct seccomp_kaddfd, list);
876 if (addfd && n.state != SECCOMP_NOTIFY_REPLIED) {
877 seccomp_handle_addfd(addfd);
878 mutex_unlock(&match->notify_lock);
879 goto wait;
880 }
881 ret = n.val;
882 err = n.error;
883 flags = n.flags;
884 }
885
886 /* If there were any pending addfd calls, clear them out */
887 list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
888 /* The process went away before we got a chance to handle it */
889 addfd->ret = -ESRCH;
890 list_del_init(&addfd->list);
891 complete(&addfd->completion);
892 }
893
894 /*
895 * Note that it's possible the listener died in between the time when
896 * we were notified of a response (or a signal) and when we were able to
897 * re-acquire the lock, so only delete from the list if the
898 * notification actually exists.
899 *
900 * Also note that this test is only valid because there's no way to
901 * *reattach* to a notifier right now. If one is added, we'll need to
902 * keep track of the notif itself and make sure they match here.
903 */
904 if (match->notif)
905 list_del(&n.list);
906out:
907 mutex_unlock(&match->notify_lock);
908
909 /* Userspace requests to continue the syscall. */
910 if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
911 return 0;
912
913 syscall_set_return_value(current, task_pt_regs(current),
914 err, ret);
915 return -1;
916}
917
918static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
919 const bool recheck_after_trace)
920{
921 u32 filter_ret, action;
922 struct seccomp_filter *match = NULL;
923 int data;
924 struct seccomp_data sd_local;
925
926 /*
927 * Make sure that any changes to mode from another thread have
928 * been seen after TIF_SECCOMP was seen.
929 */
930 rmb();
931
932 if (!sd) {
933 populate_seccomp_data(&sd_local);
934 sd = &sd_local;
935 }
936
937 filter_ret = seccomp_run_filters(sd, &match);
938 data = filter_ret & SECCOMP_RET_DATA;
939 action = filter_ret & SECCOMP_RET_ACTION_FULL;
940
941 switch (action) {
942 case SECCOMP_RET_ERRNO:
943 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
944 if (data > MAX_ERRNO)
945 data = MAX_ERRNO;
946 syscall_set_return_value(current, task_pt_regs(current),
947 -data, 0);
948 goto skip;
949
950 case SECCOMP_RET_TRAP:
951 /* Show the handler the original registers. */
952 syscall_rollback(current, task_pt_regs(current));
953 /* Let the filter pass back 16 bits of data. */
954 seccomp_send_sigsys(this_syscall, data);
955 goto skip;
956
957 case SECCOMP_RET_TRACE:
958 /* We've been put in this state by the ptracer already. */
959 if (recheck_after_trace)
960 return 0;
961
962 /* ENOSYS these calls if there is no tracer attached. */
963 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
964 syscall_set_return_value(current,
965 task_pt_regs(current),
966 -ENOSYS, 0);
967 goto skip;
968 }
969
970 /* Allow the BPF to provide the event message */
971 ptrace_event(PTRACE_EVENT_SECCOMP, data);
972 /*
973 * The delivery of a fatal signal during event
974 * notification may silently skip tracer notification,
975 * which could leave us with a potentially unmodified
976 * syscall that the tracer would have liked to have
977 * changed. Since the process is about to die, we just
978 * force the syscall to be skipped and let the signal
979 * kill the process and correctly handle any tracer exit
980 * notifications.
981 */
982 if (fatal_signal_pending(current))
983 goto skip;
984 /* Check if the tracer forced the syscall to be skipped. */
985 this_syscall = syscall_get_nr(current, task_pt_regs(current));
986 if (this_syscall < 0)
987 goto skip;
988
989 /*
990 * Recheck the syscall, since it may have changed. This
991 * intentionally uses a NULL struct seccomp_data to force
992 * a reload of all registers. This does not goto skip since
993 * a skip would have already been reported.
994 */
995 if (__seccomp_filter(this_syscall, NULL, true))
996 return -1;
997
998 return 0;
999
1000 case SECCOMP_RET_USER_NOTIF:
1001 if (seccomp_do_user_notification(this_syscall, match, sd))
1002 goto skip;
1003
1004 return 0;
1005
1006 case SECCOMP_RET_LOG:
1007 seccomp_log(this_syscall, 0, action, true);
1008 return 0;
1009
1010 case SECCOMP_RET_ALLOW:
1011 /*
1012 * Note that the "match" filter will always be NULL for
1013 * this action since SECCOMP_RET_ALLOW is the starting
1014 * state in seccomp_run_filters().
1015 */
1016 return 0;
1017
1018 case SECCOMP_RET_KILL_THREAD:
1019 case SECCOMP_RET_KILL_PROCESS:
1020 default:
1021 seccomp_log(this_syscall, SIGSYS, action, true);
1022 /* Dump core only if this is the last remaining thread. */
1023 if (action == SECCOMP_RET_KILL_PROCESS ||
1024 get_nr_threads(current) == 1) {
1025 kernel_siginfo_t info;
1026
1027 /* Show the original registers in the dump. */
1028 syscall_rollback(current, task_pt_regs(current));
1029 /* Trigger a manual coredump since do_exit skips it. */
1030 seccomp_init_siginfo(&info, this_syscall, data);
1031 do_coredump(&info);
1032 }
1033 if (action == SECCOMP_RET_KILL_PROCESS)
1034 do_group_exit(SIGSYS);
1035 else
1036 do_exit(SIGSYS);
1037 }
1038
1039 unreachable();
1040
1041skip:
1042 seccomp_log(this_syscall, 0, action, match ? match->log : false);
1043 return -1;
1044}
1045#else
1046static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1047 const bool recheck_after_trace)
1048{
1049 BUG();
1050}
1051#endif
1052
1053int __secure_computing(const struct seccomp_data *sd)
1054{
1055 int mode = current->seccomp.mode;
1056 int this_syscall;
1057
1058 if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1059 unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1060 return 0;
1061
1062 this_syscall = sd ? sd->nr :
1063 syscall_get_nr(current, task_pt_regs(current));
1064
1065 switch (mode) {
1066 case SECCOMP_MODE_STRICT:
1067 __secure_computing_strict(this_syscall); /* may call do_exit */
1068 return 0;
1069 case SECCOMP_MODE_FILTER:
1070 return __seccomp_filter(this_syscall, sd, false);
1071 default:
1072 BUG();
1073 }
1074}
1075#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1076
1077long prctl_get_seccomp(void)
1078{
1079 return current->seccomp.mode;
1080}
1081
1082/**
1083 * seccomp_set_mode_strict: internal function for setting strict seccomp
1084 *
1085 * Once current->seccomp.mode is non-zero, it may not be changed.
1086 *
1087 * Returns 0 on success or -EINVAL on failure.
1088 */
1089static long seccomp_set_mode_strict(void)
1090{
1091 const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1092 long ret = -EINVAL;
1093
1094 spin_lock_irq(¤t->sighand->siglock);
1095
1096 if (!seccomp_may_assign_mode(seccomp_mode))
1097 goto out;
1098
1099#ifdef TIF_NOTSC
1100 disable_TSC();
1101#endif
1102 seccomp_assign_mode(current, seccomp_mode, 0);
1103 ret = 0;
1104
1105out:
1106 spin_unlock_irq(¤t->sighand->siglock);
1107
1108 return ret;
1109}
1110
1111#ifdef CONFIG_SECCOMP_FILTER
1112static void seccomp_notify_free(struct seccomp_filter *filter)
1113{
1114 kfree(filter->notif);
1115 filter->notif = NULL;
1116}
1117
1118static void seccomp_notify_detach(struct seccomp_filter *filter)
1119{
1120 struct seccomp_knotif *knotif;
1121
1122 if (!filter)
1123 return;
1124
1125 mutex_lock(&filter->notify_lock);
1126
1127 /*
1128 * If this file is being closed because e.g. the task who owned it
1129 * died, let's wake everyone up who was waiting on us.
1130 */
1131 list_for_each_entry(knotif, &filter->notif->notifications, list) {
1132 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1133 continue;
1134
1135 knotif->state = SECCOMP_NOTIFY_REPLIED;
1136 knotif->error = -ENOSYS;
1137 knotif->val = 0;
1138
1139 /*
1140 * We do not need to wake up any pending addfd messages, as
1141 * the notifier will do that for us, as this just looks
1142 * like a standard reply.
1143 */
1144 complete(&knotif->ready);
1145 }
1146
1147 seccomp_notify_free(filter);
1148 mutex_unlock(&filter->notify_lock);
1149}
1150
1151static int seccomp_notify_release(struct inode *inode, struct file *file)
1152{
1153 struct seccomp_filter *filter = file->private_data;
1154
1155 seccomp_notify_detach(filter);
1156 __put_seccomp_filter(filter);
1157 return 0;
1158}
1159
1160/* must be called with notif_lock held */
1161static inline struct seccomp_knotif *
1162find_notification(struct seccomp_filter *filter, u64 id)
1163{
1164 struct seccomp_knotif *cur;
1165
1166 lockdep_assert_held(&filter->notify_lock);
1167
1168 list_for_each_entry(cur, &filter->notif->notifications, list) {
1169 if (cur->id == id)
1170 return cur;
1171 }
1172
1173 return NULL;
1174}
1175
1176
1177static long seccomp_notify_recv(struct seccomp_filter *filter,
1178 void __user *buf)
1179{
1180 struct seccomp_knotif *knotif = NULL, *cur;
1181 struct seccomp_notif unotif;
1182 ssize_t ret;
1183
1184 /* Verify that we're not given garbage to keep struct extensible. */
1185 ret = check_zeroed_user(buf, sizeof(unotif));
1186 if (ret < 0)
1187 return ret;
1188 if (!ret)
1189 return -EINVAL;
1190
1191 memset(&unotif, 0, sizeof(unotif));
1192
1193 ret = down_interruptible(&filter->notif->request);
1194 if (ret < 0)
1195 return ret;
1196
1197 mutex_lock(&filter->notify_lock);
1198 list_for_each_entry(cur, &filter->notif->notifications, list) {
1199 if (cur->state == SECCOMP_NOTIFY_INIT) {
1200 knotif = cur;
1201 break;
1202 }
1203 }
1204
1205 /*
1206 * If we didn't find a notification, it could be that the task was
1207 * interrupted by a fatal signal between the time we were woken and
1208 * when we were able to acquire the rw lock.
1209 */
1210 if (!knotif) {
1211 ret = -ENOENT;
1212 goto out;
1213 }
1214
1215 unotif.id = knotif->id;
1216 unotif.pid = task_pid_vnr(knotif->task);
1217 unotif.data = *(knotif->data);
1218
1219 knotif->state = SECCOMP_NOTIFY_SENT;
1220 wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1221 ret = 0;
1222out:
1223 mutex_unlock(&filter->notify_lock);
1224
1225 if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1226 ret = -EFAULT;
1227
1228 /*
1229 * Userspace screwed up. To make sure that we keep this
1230 * notification alive, let's reset it back to INIT. It
1231 * may have died when we released the lock, so we need to make
1232 * sure it's still around.
1233 */
1234 mutex_lock(&filter->notify_lock);
1235 knotif = find_notification(filter, unotif.id);
1236 if (knotif) {
1237 knotif->state = SECCOMP_NOTIFY_INIT;
1238 up(&filter->notif->request);
1239 }
1240 mutex_unlock(&filter->notify_lock);
1241 }
1242
1243 return ret;
1244}
1245
1246static long seccomp_notify_send(struct seccomp_filter *filter,
1247 void __user *buf)
1248{
1249 struct seccomp_notif_resp resp = {};
1250 struct seccomp_knotif *knotif;
1251 long ret;
1252
1253 if (copy_from_user(&resp, buf, sizeof(resp)))
1254 return -EFAULT;
1255
1256 if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1257 return -EINVAL;
1258
1259 if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1260 (resp.error || resp.val))
1261 return -EINVAL;
1262
1263 ret = mutex_lock_interruptible(&filter->notify_lock);
1264 if (ret < 0)
1265 return ret;
1266
1267 knotif = find_notification(filter, resp.id);
1268 if (!knotif) {
1269 ret = -ENOENT;
1270 goto out;
1271 }
1272
1273 /* Allow exactly one reply. */
1274 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1275 ret = -EINPROGRESS;
1276 goto out;
1277 }
1278
1279 ret = 0;
1280 knotif->state = SECCOMP_NOTIFY_REPLIED;
1281 knotif->error = resp.error;
1282 knotif->val = resp.val;
1283 knotif->flags = resp.flags;
1284 complete(&knotif->ready);
1285out:
1286 mutex_unlock(&filter->notify_lock);
1287 return ret;
1288}
1289
1290static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1291 void __user *buf)
1292{
1293 struct seccomp_knotif *knotif;
1294 u64 id;
1295 long ret;
1296
1297 if (copy_from_user(&id, buf, sizeof(id)))
1298 return -EFAULT;
1299
1300 ret = mutex_lock_interruptible(&filter->notify_lock);
1301 if (ret < 0)
1302 return ret;
1303
1304 knotif = find_notification(filter, id);
1305 if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1306 ret = 0;
1307 else
1308 ret = -ENOENT;
1309
1310 mutex_unlock(&filter->notify_lock);
1311 return ret;
1312}
1313
1314static long seccomp_notify_addfd(struct seccomp_filter *filter,
1315 struct seccomp_notif_addfd __user *uaddfd,
1316 unsigned int size)
1317{
1318 struct seccomp_notif_addfd addfd;
1319 struct seccomp_knotif *knotif;
1320 struct seccomp_kaddfd kaddfd;
1321 int ret;
1322
1323 BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1324 BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1325
1326 if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1327 return -EINVAL;
1328
1329 ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1330 if (ret)
1331 return ret;
1332
1333 if (addfd.newfd_flags & ~O_CLOEXEC)
1334 return -EINVAL;
1335
1336 if (addfd.flags & ~SECCOMP_ADDFD_FLAG_SETFD)
1337 return -EINVAL;
1338
1339 if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1340 return -EINVAL;
1341
1342 kaddfd.file = fget(addfd.srcfd);
1343 if (!kaddfd.file)
1344 return -EBADF;
1345
1346 kaddfd.flags = addfd.newfd_flags;
1347 kaddfd.fd = (addfd.flags & SECCOMP_ADDFD_FLAG_SETFD) ?
1348 addfd.newfd : -1;
1349 init_completion(&kaddfd.completion);
1350
1351 ret = mutex_lock_interruptible(&filter->notify_lock);
1352 if (ret < 0)
1353 goto out;
1354
1355 knotif = find_notification(filter, addfd.id);
1356 if (!knotif) {
1357 ret = -ENOENT;
1358 goto out_unlock;
1359 }
1360
1361 /*
1362 * We do not want to allow for FD injection to occur before the
1363 * notification has been picked up by a userspace handler, or after
1364 * the notification has been replied to.
1365 */
1366 if (knotif->state != SECCOMP_NOTIFY_SENT) {
1367 ret = -EINPROGRESS;
1368 goto out_unlock;
1369 }
1370
1371 list_add(&kaddfd.list, &knotif->addfd);
1372 complete(&knotif->ready);
1373 mutex_unlock(&filter->notify_lock);
1374
1375 /* Now we wait for it to be processed or be interrupted */
1376 ret = wait_for_completion_interruptible(&kaddfd.completion);
1377 if (ret == 0) {
1378 /*
1379 * We had a successful completion. The other side has already
1380 * removed us from the addfd queue, and
1381 * wait_for_completion_interruptible has a memory barrier upon
1382 * success that lets us read this value directly without
1383 * locking.
1384 */
1385 ret = kaddfd.ret;
1386 goto out;
1387 }
1388
1389 mutex_lock(&filter->notify_lock);
1390 /*
1391 * Even though we were woken up by a signal and not a successful
1392 * completion, a completion may have happened in the mean time.
1393 *
1394 * We need to check again if the addfd request has been handled,
1395 * and if not, we will remove it from the queue.
1396 */
1397 if (list_empty(&kaddfd.list))
1398 ret = kaddfd.ret;
1399 else
1400 list_del(&kaddfd.list);
1401
1402out_unlock:
1403 mutex_unlock(&filter->notify_lock);
1404out:
1405 fput(kaddfd.file);
1406
1407 return ret;
1408}
1409
1410static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1411 unsigned long arg)
1412{
1413 struct seccomp_filter *filter = file->private_data;
1414 void __user *buf = (void __user *)arg;
1415
1416 /* Fixed-size ioctls */
1417 switch (cmd) {
1418 case SECCOMP_IOCTL_NOTIF_RECV:
1419 return seccomp_notify_recv(filter, buf);
1420 case SECCOMP_IOCTL_NOTIF_SEND:
1421 return seccomp_notify_send(filter, buf);
1422 case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1423 case SECCOMP_IOCTL_NOTIF_ID_VALID:
1424 return seccomp_notify_id_valid(filter, buf);
1425 }
1426
1427 /* Extensible Argument ioctls */
1428#define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1429 switch (EA_IOCTL(cmd)) {
1430 case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1431 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1432 default:
1433 return -EINVAL;
1434 }
1435}
1436
1437static __poll_t seccomp_notify_poll(struct file *file,
1438 struct poll_table_struct *poll_tab)
1439{
1440 struct seccomp_filter *filter = file->private_data;
1441 __poll_t ret = 0;
1442 struct seccomp_knotif *cur;
1443
1444 poll_wait(file, &filter->wqh, poll_tab);
1445
1446 if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1447 return EPOLLERR;
1448
1449 list_for_each_entry(cur, &filter->notif->notifications, list) {
1450 if (cur->state == SECCOMP_NOTIFY_INIT)
1451 ret |= EPOLLIN | EPOLLRDNORM;
1452 if (cur->state == SECCOMP_NOTIFY_SENT)
1453 ret |= EPOLLOUT | EPOLLWRNORM;
1454 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1455 break;
1456 }
1457
1458 mutex_unlock(&filter->notify_lock);
1459
1460 if (refcount_read(&filter->users) == 0)
1461 ret |= EPOLLHUP;
1462
1463 return ret;
1464}
1465
1466static const struct file_operations seccomp_notify_ops = {
1467 .poll = seccomp_notify_poll,
1468 .release = seccomp_notify_release,
1469 .unlocked_ioctl = seccomp_notify_ioctl,
1470 .compat_ioctl = seccomp_notify_ioctl,
1471};
1472
1473static struct file *init_listener(struct seccomp_filter *filter)
1474{
1475 struct file *ret = ERR_PTR(-EBUSY);
1476 struct seccomp_filter *cur;
1477
1478 for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1479 if (cur->notif)
1480 goto out;
1481 }
1482
1483 ret = ERR_PTR(-ENOMEM);
1484 filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1485 if (!filter->notif)
1486 goto out;
1487
1488 sema_init(&filter->notif->request, 0);
1489 filter->notif->next_id = get_random_u64();
1490 INIT_LIST_HEAD(&filter->notif->notifications);
1491
1492 ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1493 filter, O_RDWR);
1494 if (IS_ERR(ret))
1495 goto out_notif;
1496
1497 /* The file has a reference to it now */
1498 __get_seccomp_filter(filter);
1499
1500out_notif:
1501 if (IS_ERR(ret))
1502 seccomp_notify_free(filter);
1503out:
1504 return ret;
1505}
1506
1507/**
1508 * seccomp_set_mode_filter: internal function for setting seccomp filter
1509 * @flags: flags to change filter behavior
1510 * @filter: struct sock_fprog containing filter
1511 *
1512 * This function may be called repeatedly to install additional filters.
1513 * Every filter successfully installed will be evaluated (in reverse order)
1514 * for each system call the task makes.
1515 *
1516 * Once current->seccomp.mode is non-zero, it may not be changed.
1517 *
1518 * Returns 0 on success or -EINVAL on failure.
1519 */
1520static long seccomp_set_mode_filter(unsigned int flags,
1521 const char __user *filter)
1522{
1523 const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1524 struct seccomp_filter *prepared = NULL;
1525 long ret = -EINVAL;
1526 int listener = -1;
1527 struct file *listener_f = NULL;
1528
1529 /* Validate flags. */
1530 if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1531 return -EINVAL;
1532
1533 /*
1534 * In the successful case, NEW_LISTENER returns the new listener fd.
1535 * But in the failure case, TSYNC returns the thread that died. If you
1536 * combine these two flags, there's no way to tell whether something
1537 * succeeded or failed. So, let's disallow this combination if the user
1538 * has not explicitly requested no errors from TSYNC.
1539 */
1540 if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1541 (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1542 ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1543 return -EINVAL;
1544
1545 /* Prepare the new filter before holding any locks. */
1546 prepared = seccomp_prepare_user_filter(filter);
1547 if (IS_ERR(prepared))
1548 return PTR_ERR(prepared);
1549
1550 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1551 listener = get_unused_fd_flags(O_CLOEXEC);
1552 if (listener < 0) {
1553 ret = listener;
1554 goto out_free;
1555 }
1556
1557 listener_f = init_listener(prepared);
1558 if (IS_ERR(listener_f)) {
1559 put_unused_fd(listener);
1560 ret = PTR_ERR(listener_f);
1561 goto out_free;
1562 }
1563 }
1564
1565 /*
1566 * Make sure we cannot change seccomp or nnp state via TSYNC
1567 * while another thread is in the middle of calling exec.
1568 */
1569 if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1570 mutex_lock_killable(¤t->signal->cred_guard_mutex))
1571 goto out_put_fd;
1572
1573 spin_lock_irq(¤t->sighand->siglock);
1574
1575 if (!seccomp_may_assign_mode(seccomp_mode))
1576 goto out;
1577
1578 ret = seccomp_attach_filter(flags, prepared);
1579 if (ret)
1580 goto out;
1581 /* Do not free the successfully attached filter. */
1582 prepared = NULL;
1583
1584 seccomp_assign_mode(current, seccomp_mode, flags);
1585out:
1586 spin_unlock_irq(¤t->sighand->siglock);
1587 if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1588 mutex_unlock(¤t->signal->cred_guard_mutex);
1589out_put_fd:
1590 if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1591 if (ret) {
1592 listener_f->private_data = NULL;
1593 fput(listener_f);
1594 put_unused_fd(listener);
1595 seccomp_notify_detach(prepared);
1596 } else {
1597 fd_install(listener, listener_f);
1598 ret = listener;
1599 }
1600 }
1601out_free:
1602 seccomp_filter_free(prepared);
1603 return ret;
1604}
1605#else
1606static inline long seccomp_set_mode_filter(unsigned int flags,
1607 const char __user *filter)
1608{
1609 return -EINVAL;
1610}
1611#endif
1612
1613static long seccomp_get_action_avail(const char __user *uaction)
1614{
1615 u32 action;
1616
1617 if (copy_from_user(&action, uaction, sizeof(action)))
1618 return -EFAULT;
1619
1620 switch (action) {
1621 case SECCOMP_RET_KILL_PROCESS:
1622 case SECCOMP_RET_KILL_THREAD:
1623 case SECCOMP_RET_TRAP:
1624 case SECCOMP_RET_ERRNO:
1625 case SECCOMP_RET_USER_NOTIF:
1626 case SECCOMP_RET_TRACE:
1627 case SECCOMP_RET_LOG:
1628 case SECCOMP_RET_ALLOW:
1629 break;
1630 default:
1631 return -EOPNOTSUPP;
1632 }
1633
1634 return 0;
1635}
1636
1637static long seccomp_get_notif_sizes(void __user *usizes)
1638{
1639 struct seccomp_notif_sizes sizes = {
1640 .seccomp_notif = sizeof(struct seccomp_notif),
1641 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1642 .seccomp_data = sizeof(struct seccomp_data),
1643 };
1644
1645 if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1646 return -EFAULT;
1647
1648 return 0;
1649}
1650
1651/* Common entry point for both prctl and syscall. */
1652static long do_seccomp(unsigned int op, unsigned int flags,
1653 void __user *uargs)
1654{
1655 switch (op) {
1656 case SECCOMP_SET_MODE_STRICT:
1657 if (flags != 0 || uargs != NULL)
1658 return -EINVAL;
1659 return seccomp_set_mode_strict();
1660 case SECCOMP_SET_MODE_FILTER:
1661 return seccomp_set_mode_filter(flags, uargs);
1662 case SECCOMP_GET_ACTION_AVAIL:
1663 if (flags != 0)
1664 return -EINVAL;
1665
1666 return seccomp_get_action_avail(uargs);
1667 case SECCOMP_GET_NOTIF_SIZES:
1668 if (flags != 0)
1669 return -EINVAL;
1670
1671 return seccomp_get_notif_sizes(uargs);
1672 default:
1673 return -EINVAL;
1674 }
1675}
1676
1677SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1678 void __user *, uargs)
1679{
1680 return do_seccomp(op, flags, uargs);
1681}
1682
1683/**
1684 * prctl_set_seccomp: configures current->seccomp.mode
1685 * @seccomp_mode: requested mode to use
1686 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1687 *
1688 * Returns 0 on success or -EINVAL on failure.
1689 */
1690long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1691{
1692 unsigned int op;
1693 void __user *uargs;
1694
1695 switch (seccomp_mode) {
1696 case SECCOMP_MODE_STRICT:
1697 op = SECCOMP_SET_MODE_STRICT;
1698 /*
1699 * Setting strict mode through prctl always ignored filter,
1700 * so make sure it is always NULL here to pass the internal
1701 * check in do_seccomp().
1702 */
1703 uargs = NULL;
1704 break;
1705 case SECCOMP_MODE_FILTER:
1706 op = SECCOMP_SET_MODE_FILTER;
1707 uargs = filter;
1708 break;
1709 default:
1710 return -EINVAL;
1711 }
1712
1713 /* prctl interface doesn't have flags, so they are always zero. */
1714 return do_seccomp(op, 0, uargs);
1715}
1716
1717#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1718static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1719 unsigned long filter_off)
1720{
1721 struct seccomp_filter *orig, *filter;
1722 unsigned long count;
1723
1724 /*
1725 * Note: this is only correct because the caller should be the (ptrace)
1726 * tracer of the task, otherwise lock_task_sighand is needed.
1727 */
1728 spin_lock_irq(&task->sighand->siglock);
1729
1730 if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
1731 spin_unlock_irq(&task->sighand->siglock);
1732 return ERR_PTR(-EINVAL);
1733 }
1734
1735 orig = task->seccomp.filter;
1736 __get_seccomp_filter(orig);
1737 spin_unlock_irq(&task->sighand->siglock);
1738
1739 count = 0;
1740 for (filter = orig; filter; filter = filter->prev)
1741 count++;
1742
1743 if (filter_off >= count) {
1744 filter = ERR_PTR(-ENOENT);
1745 goto out;
1746 }
1747
1748 count -= filter_off;
1749 for (filter = orig; filter && count > 1; filter = filter->prev)
1750 count--;
1751
1752 if (WARN_ON(count != 1 || !filter)) {
1753 filter = ERR_PTR(-ENOENT);
1754 goto out;
1755 }
1756
1757 __get_seccomp_filter(filter);
1758
1759out:
1760 __put_seccomp_filter(orig);
1761 return filter;
1762}
1763
1764long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
1765 void __user *data)
1766{
1767 struct seccomp_filter *filter;
1768 struct sock_fprog_kern *fprog;
1769 long ret;
1770
1771 if (!capable(CAP_SYS_ADMIN) ||
1772 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1773 return -EACCES;
1774 }
1775
1776 filter = get_nth_filter(task, filter_off);
1777 if (IS_ERR(filter))
1778 return PTR_ERR(filter);
1779
1780 fprog = filter->prog->orig_prog;
1781 if (!fprog) {
1782 /* This must be a new non-cBPF filter, since we save
1783 * every cBPF filter's orig_prog above when
1784 * CONFIG_CHECKPOINT_RESTORE is enabled.
1785 */
1786 ret = -EMEDIUMTYPE;
1787 goto out;
1788 }
1789
1790 ret = fprog->len;
1791 if (!data)
1792 goto out;
1793
1794 if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
1795 ret = -EFAULT;
1796
1797out:
1798 __put_seccomp_filter(filter);
1799 return ret;
1800}
1801
1802long seccomp_get_metadata(struct task_struct *task,
1803 unsigned long size, void __user *data)
1804{
1805 long ret;
1806 struct seccomp_filter *filter;
1807 struct seccomp_metadata kmd = {};
1808
1809 if (!capable(CAP_SYS_ADMIN) ||
1810 current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1811 return -EACCES;
1812 }
1813
1814 size = min_t(unsigned long, size, sizeof(kmd));
1815
1816 if (size < sizeof(kmd.filter_off))
1817 return -EINVAL;
1818
1819 if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
1820 return -EFAULT;
1821
1822 filter = get_nth_filter(task, kmd.filter_off);
1823 if (IS_ERR(filter))
1824 return PTR_ERR(filter);
1825
1826 if (filter->log)
1827 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
1828
1829 ret = size;
1830 if (copy_to_user(data, &kmd, size))
1831 ret = -EFAULT;
1832
1833 __put_seccomp_filter(filter);
1834 return ret;
1835}
1836#endif
1837
1838#ifdef CONFIG_SYSCTL
1839
1840/* Human readable action names for friendly sysctl interaction */
1841#define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
1842#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
1843#define SECCOMP_RET_TRAP_NAME "trap"
1844#define SECCOMP_RET_ERRNO_NAME "errno"
1845#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
1846#define SECCOMP_RET_TRACE_NAME "trace"
1847#define SECCOMP_RET_LOG_NAME "log"
1848#define SECCOMP_RET_ALLOW_NAME "allow"
1849
1850static const char seccomp_actions_avail[] =
1851 SECCOMP_RET_KILL_PROCESS_NAME " "
1852 SECCOMP_RET_KILL_THREAD_NAME " "
1853 SECCOMP_RET_TRAP_NAME " "
1854 SECCOMP_RET_ERRNO_NAME " "
1855 SECCOMP_RET_USER_NOTIF_NAME " "
1856 SECCOMP_RET_TRACE_NAME " "
1857 SECCOMP_RET_LOG_NAME " "
1858 SECCOMP_RET_ALLOW_NAME;
1859
1860struct seccomp_log_name {
1861 u32 log;
1862 const char *name;
1863};
1864
1865static const struct seccomp_log_name seccomp_log_names[] = {
1866 { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
1867 { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
1868 { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
1869 { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
1870 { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
1871 { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
1872 { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
1873 { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
1874 { }
1875};
1876
1877static bool seccomp_names_from_actions_logged(char *names, size_t size,
1878 u32 actions_logged,
1879 const char *sep)
1880{
1881 const struct seccomp_log_name *cur;
1882 bool append_sep = false;
1883
1884 for (cur = seccomp_log_names; cur->name && size; cur++) {
1885 ssize_t ret;
1886
1887 if (!(actions_logged & cur->log))
1888 continue;
1889
1890 if (append_sep) {
1891 ret = strscpy(names, sep, size);
1892 if (ret < 0)
1893 return false;
1894
1895 names += ret;
1896 size -= ret;
1897 } else
1898 append_sep = true;
1899
1900 ret = strscpy(names, cur->name, size);
1901 if (ret < 0)
1902 return false;
1903
1904 names += ret;
1905 size -= ret;
1906 }
1907
1908 return true;
1909}
1910
1911static bool seccomp_action_logged_from_name(u32 *action_logged,
1912 const char *name)
1913{
1914 const struct seccomp_log_name *cur;
1915
1916 for (cur = seccomp_log_names; cur->name; cur++) {
1917 if (!strcmp(cur->name, name)) {
1918 *action_logged = cur->log;
1919 return true;
1920 }
1921 }
1922
1923 return false;
1924}
1925
1926static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
1927{
1928 char *name;
1929
1930 *actions_logged = 0;
1931 while ((name = strsep(&names, " ")) && *name) {
1932 u32 action_logged = 0;
1933
1934 if (!seccomp_action_logged_from_name(&action_logged, name))
1935 return false;
1936
1937 *actions_logged |= action_logged;
1938 }
1939
1940 return true;
1941}
1942
1943static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1944 size_t *lenp, loff_t *ppos)
1945{
1946 char names[sizeof(seccomp_actions_avail)];
1947 struct ctl_table table;
1948
1949 memset(names, 0, sizeof(names));
1950
1951 if (!seccomp_names_from_actions_logged(names, sizeof(names),
1952 seccomp_actions_logged, " "))
1953 return -EINVAL;
1954
1955 table = *ro_table;
1956 table.data = names;
1957 table.maxlen = sizeof(names);
1958 return proc_dostring(&table, 0, buffer, lenp, ppos);
1959}
1960
1961static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1962 size_t *lenp, loff_t *ppos, u32 *actions_logged)
1963{
1964 char names[sizeof(seccomp_actions_avail)];
1965 struct ctl_table table;
1966 int ret;
1967
1968 if (!capable(CAP_SYS_ADMIN))
1969 return -EPERM;
1970
1971 memset(names, 0, sizeof(names));
1972
1973 table = *ro_table;
1974 table.data = names;
1975 table.maxlen = sizeof(names);
1976 ret = proc_dostring(&table, 1, buffer, lenp, ppos);
1977 if (ret)
1978 return ret;
1979
1980 if (!seccomp_actions_logged_from_names(actions_logged, table.data))
1981 return -EINVAL;
1982
1983 if (*actions_logged & SECCOMP_LOG_ALLOW)
1984 return -EINVAL;
1985
1986 seccomp_actions_logged = *actions_logged;
1987 return 0;
1988}
1989
1990static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
1991 int ret)
1992{
1993 char names[sizeof(seccomp_actions_avail)];
1994 char old_names[sizeof(seccomp_actions_avail)];
1995 const char *new = names;
1996 const char *old = old_names;
1997
1998 if (!audit_enabled)
1999 return;
2000
2001 memset(names, 0, sizeof(names));
2002 memset(old_names, 0, sizeof(old_names));
2003
2004 if (ret)
2005 new = "?";
2006 else if (!actions_logged)
2007 new = "(none)";
2008 else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2009 actions_logged, ","))
2010 new = "?";
2011
2012 if (!old_actions_logged)
2013 old = "(none)";
2014 else if (!seccomp_names_from_actions_logged(old_names,
2015 sizeof(old_names),
2016 old_actions_logged, ","))
2017 old = "?";
2018
2019 return audit_seccomp_actions_logged(new, old, !ret);
2020}
2021
2022static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2023 void *buffer, size_t *lenp,
2024 loff_t *ppos)
2025{
2026 int ret;
2027
2028 if (write) {
2029 u32 actions_logged = 0;
2030 u32 old_actions_logged = seccomp_actions_logged;
2031
2032 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2033 &actions_logged);
2034 audit_actions_logged(actions_logged, old_actions_logged, ret);
2035 } else
2036 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2037
2038 return ret;
2039}
2040
2041static struct ctl_path seccomp_sysctl_path[] = {
2042 { .procname = "kernel", },
2043 { .procname = "seccomp", },
2044 { }
2045};
2046
2047static struct ctl_table seccomp_sysctl_table[] = {
2048 {
2049 .procname = "actions_avail",
2050 .data = (void *) &seccomp_actions_avail,
2051 .maxlen = sizeof(seccomp_actions_avail),
2052 .mode = 0444,
2053 .proc_handler = proc_dostring,
2054 },
2055 {
2056 .procname = "actions_logged",
2057 .mode = 0644,
2058 .proc_handler = seccomp_actions_logged_handler,
2059 },
2060 { }
2061};
2062
2063static int __init seccomp_sysctl_init(void)
2064{
2065 struct ctl_table_header *hdr;
2066
2067 hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
2068 if (!hdr)
2069 pr_warn("sysctl registration failed\n");
2070 else
2071 kmemleak_not_leak(hdr);
2072
2073 return 0;
2074}
2075
2076device_initcall(seccomp_sysctl_init)
2077
2078#endif /* CONFIG_SYSCTL */