Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid
[linux-2.6-microblaze.git] / kernel / seccomp.c
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/capability.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
55 enum notify_state {
56         SECCOMP_NOTIFY_INIT,
57         SECCOMP_NOTIFY_SENT,
58         SECCOMP_NOTIFY_REPLIED,
59 };
60
61 struct seccomp_knotif {
62         /* The struct pid of the task whose filter triggered the notification */
63         struct task_struct *task;
64
65         /* The "cookie" for this request; this is unique for this filter. */
66         u64 id;
67
68         /*
69          * The seccomp data. This pointer is valid the entire time this
70          * notification is active, since it comes from __seccomp_filter which
71          * eclipses the entire lifecycle here.
72          */
73         const struct seccomp_data *data;
74
75         /*
76          * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
77          * struct seccomp_knotif is created and starts out in INIT. Once the
78          * handler reads the notification off of an FD, it transitions to SENT.
79          * If a signal is received the state transitions back to INIT and
80          * another message is sent. When the userspace handler replies, state
81          * transitions to REPLIED.
82          */
83         enum notify_state state;
84
85         /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
86         int error;
87         long val;
88         u32 flags;
89
90         /*
91          * Signals when this has changed states, such as the listener
92          * dying, a new seccomp addfd message, or changing to REPLIED
93          */
94         struct completion ready;
95
96         struct list_head list;
97
98         /* outstanding addfd requests */
99         struct list_head addfd;
100 };
101
102 /**
103  * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
104  *
105  * @file: A reference to the file to install in the other task
106  * @fd: The fd number to install it at. If the fd number is -1, it means the
107  *      installing process should allocate the fd as normal.
108  * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
109  *         is allowed.
110  * @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  */
117 struct seccomp_kaddfd {
118         struct file *file;
119         int fd;
120         unsigned int flags;
121
122         union {
123                 bool setfd;
124                 /* To only be set on reply */
125                 int ret;
126         };
127         struct completion completion;
128         struct list_head list;
129 };
130
131 /**
132  * struct notification - container for seccomp userspace notifications. Since
133  * most seccomp filters will not have notification listeners attached and this
134  * structure is fairly large, we store the notification-specific stuff in a
135  * separate structure.
136  *
137  * @request: A semaphore that users of this notification can wait on for
138  *           changes. Actual reads and writes are still controlled with
139  *           filter->notify_lock.
140  * @next_id: The id of the next request.
141  * @notifications: A list of struct seccomp_knotif elements.
142  */
143 struct notification {
144         struct semaphore request;
145         u64 next_id;
146         struct list_head notifications;
147 };
148
149 #ifdef SECCOMP_ARCH_NATIVE
150 /**
151  * struct action_cache - per-filter cache of seccomp actions per
152  * arch/syscall pair
153  *
154  * @allow_native: A bitmap where each bit represents whether the
155  *                filter will always allow the syscall, for the
156  *                native architecture.
157  * @allow_compat: A bitmap where each bit represents whether the
158  *                filter will always allow the syscall, for the
159  *                compat architecture.
160  */
161 struct action_cache {
162         DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
163 #ifdef SECCOMP_ARCH_COMPAT
164         DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
165 #endif
166 };
167 #else
168 struct action_cache { };
169
170 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
171                                              const struct seccomp_data *sd)
172 {
173         return false;
174 }
175
176 static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
177 {
178 }
179 #endif /* SECCOMP_ARCH_NATIVE */
180
181 /**
182  * struct seccomp_filter - container for seccomp BPF programs
183  *
184  * @refs: Reference count to manage the object lifetime.
185  *        A filter's reference count is incremented for each directly
186  *        attached task, once for the dependent filter, and if
187  *        requested for the user notifier. When @refs reaches zero,
188  *        the filter can be freed.
189  * @users: A filter's @users count is incremented for each directly
190  *         attached task (filter installation, fork(), thread_sync),
191  *         and once for the dependent filter (tracked in filter->prev).
192  *         When it reaches zero it indicates that no direct or indirect
193  *         users of that filter exist. No new tasks can get associated with
194  *         this filter after reaching 0. The @users count is always smaller
195  *         or equal to @refs. Hence, reaching 0 for @users does not mean
196  *         the filter can be freed.
197  * @cache: cache of arch/syscall mappings to actions
198  * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
199  * @prev: points to a previously installed, or inherited, filter
200  * @prog: the BPF program to evaluate
201  * @notif: the struct that holds all notification related information
202  * @notify_lock: A lock for all notification-related accesses.
203  * @wqh: A wait queue for poll if a notifier is in use.
204  *
205  * seccomp_filter objects are organized in a tree linked via the @prev
206  * pointer.  For any task, it appears to be a singly-linked list starting
207  * with current->seccomp.filter, the most recently attached or inherited filter.
208  * However, multiple filters may share a @prev node, by way of fork(), which
209  * results in a unidirectional tree existing in memory.  This is similar to
210  * how namespaces work.
211  *
212  * seccomp_filter objects should never be modified after being attached
213  * to a task_struct (other than @refs).
214  */
215 struct seccomp_filter {
216         refcount_t refs;
217         refcount_t users;
218         bool log;
219         struct action_cache cache;
220         struct seccomp_filter *prev;
221         struct bpf_prog *prog;
222         struct notification *notif;
223         struct mutex notify_lock;
224         wait_queue_head_t wqh;
225 };
226
227 /* Limit any path through the tree to 256KB worth of instructions. */
228 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
229
230 /*
231  * Endianness is explicitly ignored and left for BPF program authors to manage
232  * as per the specific architecture.
233  */
234 static void populate_seccomp_data(struct seccomp_data *sd)
235 {
236         /*
237          * Instead of using current_pt_reg(), we're already doing the work
238          * to safely fetch "current", so just use "task" everywhere below.
239          */
240         struct task_struct *task = current;
241         struct pt_regs *regs = task_pt_regs(task);
242         unsigned long args[6];
243
244         sd->nr = syscall_get_nr(task, regs);
245         sd->arch = syscall_get_arch(task);
246         syscall_get_arguments(task, regs, args);
247         sd->args[0] = args[0];
248         sd->args[1] = args[1];
249         sd->args[2] = args[2];
250         sd->args[3] = args[3];
251         sd->args[4] = args[4];
252         sd->args[5] = args[5];
253         sd->instruction_pointer = KSTK_EIP(task);
254 }
255
256 /**
257  *      seccomp_check_filter - verify seccomp filter code
258  *      @filter: filter to verify
259  *      @flen: length of filter
260  *
261  * Takes a previously checked filter (by bpf_check_classic) and
262  * redirects all filter code that loads struct sk_buff data
263  * and related data through seccomp_bpf_load.  It also
264  * enforces length and alignment checking of those loads.
265  *
266  * Returns 0 if the rule set is legal or -EINVAL if not.
267  */
268 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
269 {
270         int pc;
271         for (pc = 0; pc < flen; pc++) {
272                 struct sock_filter *ftest = &filter[pc];
273                 u16 code = ftest->code;
274                 u32 k = ftest->k;
275
276                 switch (code) {
277                 case BPF_LD | BPF_W | BPF_ABS:
278                         ftest->code = BPF_LDX | BPF_W | BPF_ABS;
279                         /* 32-bit aligned and not out of bounds. */
280                         if (k >= sizeof(struct seccomp_data) || k & 3)
281                                 return -EINVAL;
282                         continue;
283                 case BPF_LD | BPF_W | BPF_LEN:
284                         ftest->code = BPF_LD | BPF_IMM;
285                         ftest->k = sizeof(struct seccomp_data);
286                         continue;
287                 case BPF_LDX | BPF_W | BPF_LEN:
288                         ftest->code = BPF_LDX | BPF_IMM;
289                         ftest->k = sizeof(struct seccomp_data);
290                         continue;
291                 /* Explicitly include allowed calls. */
292                 case BPF_RET | BPF_K:
293                 case BPF_RET | BPF_A:
294                 case BPF_ALU | BPF_ADD | BPF_K:
295                 case BPF_ALU | BPF_ADD | BPF_X:
296                 case BPF_ALU | BPF_SUB | BPF_K:
297                 case BPF_ALU | BPF_SUB | BPF_X:
298                 case BPF_ALU | BPF_MUL | BPF_K:
299                 case BPF_ALU | BPF_MUL | BPF_X:
300                 case BPF_ALU | BPF_DIV | BPF_K:
301                 case BPF_ALU | BPF_DIV | BPF_X:
302                 case BPF_ALU | BPF_AND | BPF_K:
303                 case BPF_ALU | BPF_AND | BPF_X:
304                 case BPF_ALU | BPF_OR | BPF_K:
305                 case BPF_ALU | BPF_OR | BPF_X:
306                 case BPF_ALU | BPF_XOR | BPF_K:
307                 case BPF_ALU | BPF_XOR | BPF_X:
308                 case BPF_ALU | BPF_LSH | BPF_K:
309                 case BPF_ALU | BPF_LSH | BPF_X:
310                 case BPF_ALU | BPF_RSH | BPF_K:
311                 case BPF_ALU | BPF_RSH | BPF_X:
312                 case BPF_ALU | BPF_NEG:
313                 case BPF_LD | BPF_IMM:
314                 case BPF_LDX | BPF_IMM:
315                 case BPF_MISC | BPF_TAX:
316                 case BPF_MISC | BPF_TXA:
317                 case BPF_LD | BPF_MEM:
318                 case BPF_LDX | BPF_MEM:
319                 case BPF_ST:
320                 case BPF_STX:
321                 case BPF_JMP | BPF_JA:
322                 case BPF_JMP | BPF_JEQ | BPF_K:
323                 case BPF_JMP | BPF_JEQ | BPF_X:
324                 case BPF_JMP | BPF_JGE | BPF_K:
325                 case BPF_JMP | BPF_JGE | BPF_X:
326                 case BPF_JMP | BPF_JGT | BPF_K:
327                 case BPF_JMP | BPF_JGT | BPF_X:
328                 case BPF_JMP | BPF_JSET | BPF_K:
329                 case BPF_JMP | BPF_JSET | BPF_X:
330                         continue;
331                 default:
332                         return -EINVAL;
333                 }
334         }
335         return 0;
336 }
337
338 #ifdef SECCOMP_ARCH_NATIVE
339 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
340                                                     size_t bitmap_size,
341                                                     int syscall_nr)
342 {
343         if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
344                 return false;
345         syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
346
347         return test_bit(syscall_nr, bitmap);
348 }
349
350 /**
351  * seccomp_cache_check_allow - lookup seccomp cache
352  * @sfilter: The seccomp filter
353  * @sd: The seccomp data to lookup the cache with
354  *
355  * Returns true if the seccomp_data is cached and allowed.
356  */
357 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
358                                              const struct seccomp_data *sd)
359 {
360         int syscall_nr = sd->nr;
361         const struct action_cache *cache = &sfilter->cache;
362
363 #ifndef SECCOMP_ARCH_COMPAT
364         /* A native-only architecture doesn't need to check sd->arch. */
365         return seccomp_cache_check_allow_bitmap(cache->allow_native,
366                                                 SECCOMP_ARCH_NATIVE_NR,
367                                                 syscall_nr);
368 #else
369         if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
370                 return seccomp_cache_check_allow_bitmap(cache->allow_native,
371                                                         SECCOMP_ARCH_NATIVE_NR,
372                                                         syscall_nr);
373         if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
374                 return seccomp_cache_check_allow_bitmap(cache->allow_compat,
375                                                         SECCOMP_ARCH_COMPAT_NR,
376                                                         syscall_nr);
377 #endif /* SECCOMP_ARCH_COMPAT */
378
379         WARN_ON_ONCE(true);
380         return false;
381 }
382 #endif /* SECCOMP_ARCH_NATIVE */
383
384 /**
385  * seccomp_run_filters - evaluates all seccomp filters against @sd
386  * @sd: optional seccomp data to be passed to filters
387  * @match: stores struct seccomp_filter that resulted in the return value,
388  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
389  *         be unchanged.
390  *
391  * Returns valid seccomp BPF response codes.
392  */
393 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
394 static u32 seccomp_run_filters(const struct seccomp_data *sd,
395                                struct seccomp_filter **match)
396 {
397         u32 ret = SECCOMP_RET_ALLOW;
398         /* Make sure cross-thread synced filter points somewhere sane. */
399         struct seccomp_filter *f =
400                         READ_ONCE(current->seccomp.filter);
401
402         /* Ensure unexpected behavior doesn't result in failing open. */
403         if (WARN_ON(f == NULL))
404                 return SECCOMP_RET_KILL_PROCESS;
405
406         if (seccomp_cache_check_allow(f, sd))
407                 return SECCOMP_RET_ALLOW;
408
409         /*
410          * All filters in the list are evaluated and the lowest BPF return
411          * value always takes priority (ignoring the DATA).
412          */
413         for (; f; f = f->prev) {
414                 u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
415
416                 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
417                         ret = cur_ret;
418                         *match = f;
419                 }
420         }
421         return ret;
422 }
423 #endif /* CONFIG_SECCOMP_FILTER */
424
425 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
426 {
427         assert_spin_locked(&current->sighand->siglock);
428
429         if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
430                 return false;
431
432         return true;
433 }
434
435 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
436
437 static inline void seccomp_assign_mode(struct task_struct *task,
438                                        unsigned long seccomp_mode,
439                                        unsigned long flags)
440 {
441         assert_spin_locked(&task->sighand->siglock);
442
443         task->seccomp.mode = seccomp_mode;
444         /*
445          * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
446          * filter) is set.
447          */
448         smp_mb__before_atomic();
449         /* Assume default seccomp processes want spec flaw mitigation. */
450         if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
451                 arch_seccomp_spec_mitigate(task);
452         set_task_syscall_work(task, SECCOMP);
453 }
454
455 #ifdef CONFIG_SECCOMP_FILTER
456 /* Returns 1 if the parent is an ancestor of the child. */
457 static int is_ancestor(struct seccomp_filter *parent,
458                        struct seccomp_filter *child)
459 {
460         /* NULL is the root ancestor. */
461         if (parent == NULL)
462                 return 1;
463         for (; child; child = child->prev)
464                 if (child == parent)
465                         return 1;
466         return 0;
467 }
468
469 /**
470  * seccomp_can_sync_threads: checks if all threads can be synchronized
471  *
472  * Expects sighand and cred_guard_mutex locks to be held.
473  *
474  * Returns 0 on success, -ve on error, or the pid of a thread which was
475  * either not in the correct seccomp mode or did not have an ancestral
476  * seccomp filter.
477  */
478 static inline pid_t seccomp_can_sync_threads(void)
479 {
480         struct task_struct *thread, *caller;
481
482         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
483         assert_spin_locked(&current->sighand->siglock);
484
485         /* Validate all threads being eligible for synchronization. */
486         caller = current;
487         for_each_thread(caller, thread) {
488                 pid_t failed;
489
490                 /* Skip current, since it is initiating the sync. */
491                 if (thread == caller)
492                         continue;
493
494                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
495                     (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
496                      is_ancestor(thread->seccomp.filter,
497                                  caller->seccomp.filter)))
498                         continue;
499
500                 /* Return the first thread that cannot be synchronized. */
501                 failed = task_pid_vnr(thread);
502                 /* If the pid cannot be resolved, then return -ESRCH */
503                 if (WARN_ON(failed == 0))
504                         failed = -ESRCH;
505                 return failed;
506         }
507
508         return 0;
509 }
510
511 static inline void seccomp_filter_free(struct seccomp_filter *filter)
512 {
513         if (filter) {
514                 bpf_prog_destroy(filter->prog);
515                 kfree(filter);
516         }
517 }
518
519 static void __seccomp_filter_orphan(struct seccomp_filter *orig)
520 {
521         while (orig && refcount_dec_and_test(&orig->users)) {
522                 if (waitqueue_active(&orig->wqh))
523                         wake_up_poll(&orig->wqh, EPOLLHUP);
524                 orig = orig->prev;
525         }
526 }
527
528 static void __put_seccomp_filter(struct seccomp_filter *orig)
529 {
530         /* Clean up single-reference branches iteratively. */
531         while (orig && refcount_dec_and_test(&orig->refs)) {
532                 struct seccomp_filter *freeme = orig;
533                 orig = orig->prev;
534                 seccomp_filter_free(freeme);
535         }
536 }
537
538 static void __seccomp_filter_release(struct seccomp_filter *orig)
539 {
540         /* Notify about any unused filters in the task's former filter tree. */
541         __seccomp_filter_orphan(orig);
542         /* Finally drop all references to the task's former tree. */
543         __put_seccomp_filter(orig);
544 }
545
546 /**
547  * seccomp_filter_release - Detach the task from its filter tree,
548  *                          drop its reference count, and notify
549  *                          about unused filters
550  *
551  * This function should only be called when the task is exiting as
552  * it detaches it from its filter tree. As such, READ_ONCE() and
553  * barriers are not needed here, as would normally be needed.
554  */
555 void seccomp_filter_release(struct task_struct *tsk)
556 {
557         struct seccomp_filter *orig = tsk->seccomp.filter;
558
559         /* We are effectively holding the siglock by not having any sighand. */
560         WARN_ON(tsk->sighand != NULL);
561
562         /* Detach task from its filter tree. */
563         tsk->seccomp.filter = NULL;
564         __seccomp_filter_release(orig);
565 }
566
567 /**
568  * seccomp_sync_threads: sets all threads to use current's filter
569  *
570  * Expects sighand and cred_guard_mutex locks to be held, and for
571  * seccomp_can_sync_threads() to have returned success already
572  * without dropping the locks.
573  *
574  */
575 static inline void seccomp_sync_threads(unsigned long flags)
576 {
577         struct task_struct *thread, *caller;
578
579         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
580         assert_spin_locked(&current->sighand->siglock);
581
582         /* Synchronize all threads. */
583         caller = current;
584         for_each_thread(caller, thread) {
585                 /* Skip current, since it needs no changes. */
586                 if (thread == caller)
587                         continue;
588
589                 /* Get a task reference for the new leaf node. */
590                 get_seccomp_filter(caller);
591
592                 /*
593                  * Drop the task reference to the shared ancestor since
594                  * current's path will hold a reference.  (This also
595                  * allows a put before the assignment.)
596                  */
597                 __seccomp_filter_release(thread->seccomp.filter);
598
599                 /* Make our new filter tree visible. */
600                 smp_store_release(&thread->seccomp.filter,
601                                   caller->seccomp.filter);
602                 atomic_set(&thread->seccomp.filter_count,
603                            atomic_read(&thread->seccomp.filter_count));
604
605                 /*
606                  * Don't let an unprivileged task work around
607                  * the no_new_privs restriction by creating
608                  * a thread that sets it up, enters seccomp,
609                  * then dies.
610                  */
611                 if (task_no_new_privs(caller))
612                         task_set_no_new_privs(thread);
613
614                 /*
615                  * Opt the other thread into seccomp if needed.
616                  * As threads are considered to be trust-realm
617                  * equivalent (see ptrace_may_access), it is safe to
618                  * allow one thread to transition the other.
619                  */
620                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
621                         seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
622                                             flags);
623         }
624 }
625
626 /**
627  * seccomp_prepare_filter: Prepares a seccomp filter for use.
628  * @fprog: BPF program to install
629  *
630  * Returns filter on success or an ERR_PTR on failure.
631  */
632 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
633 {
634         struct seccomp_filter *sfilter;
635         int ret;
636         const bool save_orig =
637 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
638                 true;
639 #else
640                 false;
641 #endif
642
643         if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
644                 return ERR_PTR(-EINVAL);
645
646         BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
647
648         /*
649          * Installing a seccomp filter requires that the task has
650          * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
651          * This avoids scenarios where unprivileged tasks can affect the
652          * behavior of privileged children.
653          */
654         if (!task_no_new_privs(current) &&
655                         !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
656                 return ERR_PTR(-EACCES);
657
658         /* Allocate a new seccomp_filter */
659         sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
660         if (!sfilter)
661                 return ERR_PTR(-ENOMEM);
662
663         mutex_init(&sfilter->notify_lock);
664         ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
665                                         seccomp_check_filter, save_orig);
666         if (ret < 0) {
667                 kfree(sfilter);
668                 return ERR_PTR(ret);
669         }
670
671         refcount_set(&sfilter->refs, 1);
672         refcount_set(&sfilter->users, 1);
673         init_waitqueue_head(&sfilter->wqh);
674
675         return sfilter;
676 }
677
678 /**
679  * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
680  * @user_filter: pointer to the user data containing a sock_fprog.
681  *
682  * Returns 0 on success and non-zero otherwise.
683  */
684 static struct seccomp_filter *
685 seccomp_prepare_user_filter(const char __user *user_filter)
686 {
687         struct sock_fprog fprog;
688         struct seccomp_filter *filter = ERR_PTR(-EFAULT);
689
690 #ifdef CONFIG_COMPAT
691         if (in_compat_syscall()) {
692                 struct compat_sock_fprog fprog32;
693                 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
694                         goto out;
695                 fprog.len = fprog32.len;
696                 fprog.filter = compat_ptr(fprog32.filter);
697         } else /* falls through to the if below. */
698 #endif
699         if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
700                 goto out;
701         filter = seccomp_prepare_filter(&fprog);
702 out:
703         return filter;
704 }
705
706 #ifdef SECCOMP_ARCH_NATIVE
707 /**
708  * seccomp_is_const_allow - check if filter is constant allow with given data
709  * @fprog: The BPF programs
710  * @sd: The seccomp data to check against, only syscall number and arch
711  *      number are considered constant.
712  */
713 static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
714                                    struct seccomp_data *sd)
715 {
716         unsigned int reg_value = 0;
717         unsigned int pc;
718         bool op_res;
719
720         if (WARN_ON_ONCE(!fprog))
721                 return false;
722
723         for (pc = 0; pc < fprog->len; pc++) {
724                 struct sock_filter *insn = &fprog->filter[pc];
725                 u16 code = insn->code;
726                 u32 k = insn->k;
727
728                 switch (code) {
729                 case BPF_LD | BPF_W | BPF_ABS:
730                         switch (k) {
731                         case offsetof(struct seccomp_data, nr):
732                                 reg_value = sd->nr;
733                                 break;
734                         case offsetof(struct seccomp_data, arch):
735                                 reg_value = sd->arch;
736                                 break;
737                         default:
738                                 /* can't optimize (non-constant value load) */
739                                 return false;
740                         }
741                         break;
742                 case BPF_RET | BPF_K:
743                         /* reached return with constant values only, check allow */
744                         return k == SECCOMP_RET_ALLOW;
745                 case BPF_JMP | BPF_JA:
746                         pc += insn->k;
747                         break;
748                 case BPF_JMP | BPF_JEQ | BPF_K:
749                 case BPF_JMP | BPF_JGE | BPF_K:
750                 case BPF_JMP | BPF_JGT | BPF_K:
751                 case BPF_JMP | BPF_JSET | BPF_K:
752                         switch (BPF_OP(code)) {
753                         case BPF_JEQ:
754                                 op_res = reg_value == k;
755                                 break;
756                         case BPF_JGE:
757                                 op_res = reg_value >= k;
758                                 break;
759                         case BPF_JGT:
760                                 op_res = reg_value > k;
761                                 break;
762                         case BPF_JSET:
763                                 op_res = !!(reg_value & k);
764                                 break;
765                         default:
766                                 /* can't optimize (unknown jump) */
767                                 return false;
768                         }
769
770                         pc += op_res ? insn->jt : insn->jf;
771                         break;
772                 case BPF_ALU | BPF_AND | BPF_K:
773                         reg_value &= k;
774                         break;
775                 default:
776                         /* can't optimize (unknown insn) */
777                         return false;
778                 }
779         }
780
781         /* ran off the end of the filter?! */
782         WARN_ON(1);
783         return false;
784 }
785
786 static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
787                                          void *bitmap, const void *bitmap_prev,
788                                          size_t bitmap_size, int arch)
789 {
790         struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
791         struct seccomp_data sd;
792         int nr;
793
794         if (bitmap_prev) {
795                 /* The new filter must be as restrictive as the last. */
796                 bitmap_copy(bitmap, bitmap_prev, bitmap_size);
797         } else {
798                 /* Before any filters, all syscalls are always allowed. */
799                 bitmap_fill(bitmap, bitmap_size);
800         }
801
802         for (nr = 0; nr < bitmap_size; nr++) {
803                 /* No bitmap change: not a cacheable action. */
804                 if (!test_bit(nr, bitmap))
805                         continue;
806
807                 sd.nr = nr;
808                 sd.arch = arch;
809
810                 /* No bitmap change: continue to always allow. */
811                 if (seccomp_is_const_allow(fprog, &sd))
812                         continue;
813
814                 /*
815                  * Not a cacheable action: always run filters.
816                  * atomic clear_bit() not needed, filter not visible yet.
817                  */
818                 __clear_bit(nr, bitmap);
819         }
820 }
821
822 /**
823  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
824  * @sfilter: The seccomp filter
825  *
826  * Returns 0 if successful or -errno if error occurred.
827  */
828 static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
829 {
830         struct action_cache *cache = &sfilter->cache;
831         const struct action_cache *cache_prev =
832                 sfilter->prev ? &sfilter->prev->cache : NULL;
833
834         seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
835                                      cache_prev ? cache_prev->allow_native : NULL,
836                                      SECCOMP_ARCH_NATIVE_NR,
837                                      SECCOMP_ARCH_NATIVE);
838
839 #ifdef SECCOMP_ARCH_COMPAT
840         seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
841                                      cache_prev ? cache_prev->allow_compat : NULL,
842                                      SECCOMP_ARCH_COMPAT_NR,
843                                      SECCOMP_ARCH_COMPAT);
844 #endif /* SECCOMP_ARCH_COMPAT */
845 }
846 #endif /* SECCOMP_ARCH_NATIVE */
847
848 /**
849  * seccomp_attach_filter: validate and attach filter
850  * @flags:  flags to change filter behavior
851  * @filter: seccomp filter to add to the current process
852  *
853  * Caller must be holding current->sighand->siglock lock.
854  *
855  * Returns 0 on success, -ve on error, or
856  *   - in TSYNC mode: the pid of a thread which was either not in the correct
857  *     seccomp mode or did not have an ancestral seccomp filter
858  *   - in NEW_LISTENER mode: the fd of the new listener
859  */
860 static long seccomp_attach_filter(unsigned int flags,
861                                   struct seccomp_filter *filter)
862 {
863         unsigned long total_insns;
864         struct seccomp_filter *walker;
865
866         assert_spin_locked(&current->sighand->siglock);
867
868         /* Validate resulting filter length. */
869         total_insns = filter->prog->len;
870         for (walker = current->seccomp.filter; walker; walker = walker->prev)
871                 total_insns += walker->prog->len + 4;  /* 4 instr penalty */
872         if (total_insns > MAX_INSNS_PER_PATH)
873                 return -ENOMEM;
874
875         /* If thread sync has been requested, check that it is possible. */
876         if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
877                 int ret;
878
879                 ret = seccomp_can_sync_threads();
880                 if (ret) {
881                         if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
882                                 return -ESRCH;
883                         else
884                                 return ret;
885                 }
886         }
887
888         /* Set log flag, if present. */
889         if (flags & SECCOMP_FILTER_FLAG_LOG)
890                 filter->log = true;
891
892         /*
893          * If there is an existing filter, make it the prev and don't drop its
894          * task reference.
895          */
896         filter->prev = current->seccomp.filter;
897         seccomp_cache_prepare(filter);
898         current->seccomp.filter = filter;
899         atomic_inc(&current->seccomp.filter_count);
900
901         /* Now that the new filter is in place, synchronize to all threads. */
902         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
903                 seccomp_sync_threads(flags);
904
905         return 0;
906 }
907
908 static void __get_seccomp_filter(struct seccomp_filter *filter)
909 {
910         refcount_inc(&filter->refs);
911 }
912
913 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
914 void get_seccomp_filter(struct task_struct *tsk)
915 {
916         struct seccomp_filter *orig = tsk->seccomp.filter;
917         if (!orig)
918                 return;
919         __get_seccomp_filter(orig);
920         refcount_inc(&orig->users);
921 }
922
923 static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
924 {
925         clear_siginfo(info);
926         info->si_signo = SIGSYS;
927         info->si_code = SYS_SECCOMP;
928         info->si_call_addr = (void __user *)KSTK_EIP(current);
929         info->si_errno = reason;
930         info->si_arch = syscall_get_arch(current);
931         info->si_syscall = syscall;
932 }
933
934 /**
935  * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
936  * @syscall: syscall number to send to userland
937  * @reason: filter-supplied reason code to send to userland (via si_errno)
938  *
939  * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
940  */
941 static void seccomp_send_sigsys(int syscall, int reason)
942 {
943         struct kernel_siginfo info;
944         seccomp_init_siginfo(&info, syscall, reason);
945         force_sig_info(&info);
946 }
947 #endif  /* CONFIG_SECCOMP_FILTER */
948
949 /* For use with seccomp_actions_logged */
950 #define SECCOMP_LOG_KILL_PROCESS        (1 << 0)
951 #define SECCOMP_LOG_KILL_THREAD         (1 << 1)
952 #define SECCOMP_LOG_TRAP                (1 << 2)
953 #define SECCOMP_LOG_ERRNO               (1 << 3)
954 #define SECCOMP_LOG_TRACE               (1 << 4)
955 #define SECCOMP_LOG_LOG                 (1 << 5)
956 #define SECCOMP_LOG_ALLOW               (1 << 6)
957 #define SECCOMP_LOG_USER_NOTIF          (1 << 7)
958
959 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
960                                     SECCOMP_LOG_KILL_THREAD  |
961                                     SECCOMP_LOG_TRAP  |
962                                     SECCOMP_LOG_ERRNO |
963                                     SECCOMP_LOG_USER_NOTIF |
964                                     SECCOMP_LOG_TRACE |
965                                     SECCOMP_LOG_LOG;
966
967 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
968                                bool requested)
969 {
970         bool log = false;
971
972         switch (action) {
973         case SECCOMP_RET_ALLOW:
974                 break;
975         case SECCOMP_RET_TRAP:
976                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
977                 break;
978         case SECCOMP_RET_ERRNO:
979                 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
980                 break;
981         case SECCOMP_RET_TRACE:
982                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
983                 break;
984         case SECCOMP_RET_USER_NOTIF:
985                 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
986                 break;
987         case SECCOMP_RET_LOG:
988                 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
989                 break;
990         case SECCOMP_RET_KILL_THREAD:
991                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
992                 break;
993         case SECCOMP_RET_KILL_PROCESS:
994         default:
995                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
996         }
997
998         /*
999          * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
1000          * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
1001          * any action from being logged by removing the action name from the
1002          * seccomp_actions_logged sysctl.
1003          */
1004         if (!log)
1005                 return;
1006
1007         audit_seccomp(syscall, signr, action);
1008 }
1009
1010 /*
1011  * Secure computing mode 1 allows only read/write/exit/sigreturn.
1012  * To be fully secure this must be combined with rlimit
1013  * to limit the stack allocations too.
1014  */
1015 static const int mode1_syscalls[] = {
1016         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1017         -1, /* negative terminated */
1018 };
1019
1020 static void __secure_computing_strict(int this_syscall)
1021 {
1022         const int *allowed_syscalls = mode1_syscalls;
1023 #ifdef CONFIG_COMPAT
1024         if (in_compat_syscall())
1025                 allowed_syscalls = get_compat_mode1_syscalls();
1026 #endif
1027         do {
1028                 if (*allowed_syscalls == this_syscall)
1029                         return;
1030         } while (*++allowed_syscalls != -1);
1031
1032 #ifdef SECCOMP_DEBUG
1033         dump_stack();
1034 #endif
1035         seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1036         do_exit(SIGKILL);
1037 }
1038
1039 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1040 void secure_computing_strict(int this_syscall)
1041 {
1042         int mode = current->seccomp.mode;
1043
1044         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1045             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1046                 return;
1047
1048         if (mode == SECCOMP_MODE_DISABLED)
1049                 return;
1050         else if (mode == SECCOMP_MODE_STRICT)
1051                 __secure_computing_strict(this_syscall);
1052         else
1053                 BUG();
1054 }
1055 #else
1056
1057 #ifdef CONFIG_SECCOMP_FILTER
1058 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1059 {
1060         /*
1061          * Note: overflow is ok here, the id just needs to be unique per
1062          * filter.
1063          */
1064         lockdep_assert_held(&filter->notify_lock);
1065         return filter->notif->next_id++;
1066 }
1067
1068 static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
1069 {
1070         /*
1071          * Remove the notification, and reset the list pointers, indicating
1072          * that it has been handled.
1073          */
1074         list_del_init(&addfd->list);
1075         if (!addfd->setfd)
1076                 addfd->ret = receive_fd(addfd->file, addfd->flags);
1077         else
1078                 addfd->ret = receive_fd_replace(addfd->fd, addfd->file,
1079                                                 addfd->flags);
1080         complete(&addfd->completion);
1081 }
1082
1083 static int seccomp_do_user_notification(int this_syscall,
1084                                         struct seccomp_filter *match,
1085                                         const struct seccomp_data *sd)
1086 {
1087         int err;
1088         u32 flags = 0;
1089         long ret = 0;
1090         struct seccomp_knotif n = {};
1091         struct seccomp_kaddfd *addfd, *tmp;
1092
1093         mutex_lock(&match->notify_lock);
1094         err = -ENOSYS;
1095         if (!match->notif)
1096                 goto out;
1097
1098         n.task = current;
1099         n.state = SECCOMP_NOTIFY_INIT;
1100         n.data = sd;
1101         n.id = seccomp_next_notify_id(match);
1102         init_completion(&n.ready);
1103         list_add(&n.list, &match->notif->notifications);
1104         INIT_LIST_HEAD(&n.addfd);
1105
1106         up(&match->notif->request);
1107         wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1108
1109         /*
1110          * This is where we wait for a reply from userspace.
1111          */
1112         do {
1113                 mutex_unlock(&match->notify_lock);
1114                 err = wait_for_completion_interruptible(&n.ready);
1115                 mutex_lock(&match->notify_lock);
1116                 if (err != 0)
1117                         goto interrupted;
1118
1119                 addfd = list_first_entry_or_null(&n.addfd,
1120                                                  struct seccomp_kaddfd, list);
1121                 /* Check if we were woken up by a addfd message */
1122                 if (addfd)
1123                         seccomp_handle_addfd(addfd);
1124
1125         }  while (n.state != SECCOMP_NOTIFY_REPLIED);
1126
1127         ret = n.val;
1128         err = n.error;
1129         flags = n.flags;
1130
1131 interrupted:
1132         /* If there were any pending addfd calls, clear them out */
1133         list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1134                 /* The process went away before we got a chance to handle it */
1135                 addfd->ret = -ESRCH;
1136                 list_del_init(&addfd->list);
1137                 complete(&addfd->completion);
1138         }
1139
1140         /*
1141          * Note that it's possible the listener died in between the time when
1142          * we were notified of a response (or a signal) and when we were able to
1143          * re-acquire the lock, so only delete from the list if the
1144          * notification actually exists.
1145          *
1146          * Also note that this test is only valid because there's no way to
1147          * *reattach* to a notifier right now. If one is added, we'll need to
1148          * keep track of the notif itself and make sure they match here.
1149          */
1150         if (match->notif)
1151                 list_del(&n.list);
1152 out:
1153         mutex_unlock(&match->notify_lock);
1154
1155         /* Userspace requests to continue the syscall. */
1156         if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1157                 return 0;
1158
1159         syscall_set_return_value(current, current_pt_regs(),
1160                                  err, ret);
1161         return -1;
1162 }
1163
1164 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1165                             const bool recheck_after_trace)
1166 {
1167         u32 filter_ret, action;
1168         struct seccomp_filter *match = NULL;
1169         int data;
1170         struct seccomp_data sd_local;
1171
1172         /*
1173          * Make sure that any changes to mode from another thread have
1174          * been seen after SYSCALL_WORK_SECCOMP was seen.
1175          */
1176         smp_rmb();
1177
1178         if (!sd) {
1179                 populate_seccomp_data(&sd_local);
1180                 sd = &sd_local;
1181         }
1182
1183         filter_ret = seccomp_run_filters(sd, &match);
1184         data = filter_ret & SECCOMP_RET_DATA;
1185         action = filter_ret & SECCOMP_RET_ACTION_FULL;
1186
1187         switch (action) {
1188         case SECCOMP_RET_ERRNO:
1189                 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1190                 if (data > MAX_ERRNO)
1191                         data = MAX_ERRNO;
1192                 syscall_set_return_value(current, current_pt_regs(),
1193                                          -data, 0);
1194                 goto skip;
1195
1196         case SECCOMP_RET_TRAP:
1197                 /* Show the handler the original registers. */
1198                 syscall_rollback(current, current_pt_regs());
1199                 /* Let the filter pass back 16 bits of data. */
1200                 seccomp_send_sigsys(this_syscall, data);
1201                 goto skip;
1202
1203         case SECCOMP_RET_TRACE:
1204                 /* We've been put in this state by the ptracer already. */
1205                 if (recheck_after_trace)
1206                         return 0;
1207
1208                 /* ENOSYS these calls if there is no tracer attached. */
1209                 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1210                         syscall_set_return_value(current,
1211                                                  current_pt_regs(),
1212                                                  -ENOSYS, 0);
1213                         goto skip;
1214                 }
1215
1216                 /* Allow the BPF to provide the event message */
1217                 ptrace_event(PTRACE_EVENT_SECCOMP, data);
1218                 /*
1219                  * The delivery of a fatal signal during event
1220                  * notification may silently skip tracer notification,
1221                  * which could leave us with a potentially unmodified
1222                  * syscall that the tracer would have liked to have
1223                  * changed. Since the process is about to die, we just
1224                  * force the syscall to be skipped and let the signal
1225                  * kill the process and correctly handle any tracer exit
1226                  * notifications.
1227                  */
1228                 if (fatal_signal_pending(current))
1229                         goto skip;
1230                 /* Check if the tracer forced the syscall to be skipped. */
1231                 this_syscall = syscall_get_nr(current, current_pt_regs());
1232                 if (this_syscall < 0)
1233                         goto skip;
1234
1235                 /*
1236                  * Recheck the syscall, since it may have changed. This
1237                  * intentionally uses a NULL struct seccomp_data to force
1238                  * a reload of all registers. This does not goto skip since
1239                  * a skip would have already been reported.
1240                  */
1241                 if (__seccomp_filter(this_syscall, NULL, true))
1242                         return -1;
1243
1244                 return 0;
1245
1246         case SECCOMP_RET_USER_NOTIF:
1247                 if (seccomp_do_user_notification(this_syscall, match, sd))
1248                         goto skip;
1249
1250                 return 0;
1251
1252         case SECCOMP_RET_LOG:
1253                 seccomp_log(this_syscall, 0, action, true);
1254                 return 0;
1255
1256         case SECCOMP_RET_ALLOW:
1257                 /*
1258                  * Note that the "match" filter will always be NULL for
1259                  * this action since SECCOMP_RET_ALLOW is the starting
1260                  * state in seccomp_run_filters().
1261                  */
1262                 return 0;
1263
1264         case SECCOMP_RET_KILL_THREAD:
1265         case SECCOMP_RET_KILL_PROCESS:
1266         default:
1267                 seccomp_log(this_syscall, SIGSYS, action, true);
1268                 /* Dump core only if this is the last remaining thread. */
1269                 if (action != SECCOMP_RET_KILL_THREAD ||
1270                     get_nr_threads(current) == 1) {
1271                         kernel_siginfo_t info;
1272
1273                         /* Show the original registers in the dump. */
1274                         syscall_rollback(current, current_pt_regs());
1275                         /* Trigger a manual coredump since do_exit skips it. */
1276                         seccomp_init_siginfo(&info, this_syscall, data);
1277                         do_coredump(&info);
1278                 }
1279                 if (action == SECCOMP_RET_KILL_THREAD)
1280                         do_exit(SIGSYS);
1281                 else
1282                         do_group_exit(SIGSYS);
1283         }
1284
1285         unreachable();
1286
1287 skip:
1288         seccomp_log(this_syscall, 0, action, match ? match->log : false);
1289         return -1;
1290 }
1291 #else
1292 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1293                             const bool recheck_after_trace)
1294 {
1295         BUG();
1296
1297         return -1;
1298 }
1299 #endif
1300
1301 int __secure_computing(const struct seccomp_data *sd)
1302 {
1303         int mode = current->seccomp.mode;
1304         int this_syscall;
1305
1306         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1307             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1308                 return 0;
1309
1310         this_syscall = sd ? sd->nr :
1311                 syscall_get_nr(current, current_pt_regs());
1312
1313         switch (mode) {
1314         case SECCOMP_MODE_STRICT:
1315                 __secure_computing_strict(this_syscall);  /* may call do_exit */
1316                 return 0;
1317         case SECCOMP_MODE_FILTER:
1318                 return __seccomp_filter(this_syscall, sd, false);
1319         default:
1320                 BUG();
1321         }
1322 }
1323 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1324
1325 long prctl_get_seccomp(void)
1326 {
1327         return current->seccomp.mode;
1328 }
1329
1330 /**
1331  * seccomp_set_mode_strict: internal function for setting strict seccomp
1332  *
1333  * Once current->seccomp.mode is non-zero, it may not be changed.
1334  *
1335  * Returns 0 on success or -EINVAL on failure.
1336  */
1337 static long seccomp_set_mode_strict(void)
1338 {
1339         const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1340         long ret = -EINVAL;
1341
1342         spin_lock_irq(&current->sighand->siglock);
1343
1344         if (!seccomp_may_assign_mode(seccomp_mode))
1345                 goto out;
1346
1347 #ifdef TIF_NOTSC
1348         disable_TSC();
1349 #endif
1350         seccomp_assign_mode(current, seccomp_mode, 0);
1351         ret = 0;
1352
1353 out:
1354         spin_unlock_irq(&current->sighand->siglock);
1355
1356         return ret;
1357 }
1358
1359 #ifdef CONFIG_SECCOMP_FILTER
1360 static void seccomp_notify_free(struct seccomp_filter *filter)
1361 {
1362         kfree(filter->notif);
1363         filter->notif = NULL;
1364 }
1365
1366 static void seccomp_notify_detach(struct seccomp_filter *filter)
1367 {
1368         struct seccomp_knotif *knotif;
1369
1370         if (!filter)
1371                 return;
1372
1373         mutex_lock(&filter->notify_lock);
1374
1375         /*
1376          * If this file is being closed because e.g. the task who owned it
1377          * died, let's wake everyone up who was waiting on us.
1378          */
1379         list_for_each_entry(knotif, &filter->notif->notifications, list) {
1380                 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1381                         continue;
1382
1383                 knotif->state = SECCOMP_NOTIFY_REPLIED;
1384                 knotif->error = -ENOSYS;
1385                 knotif->val = 0;
1386
1387                 /*
1388                  * We do not need to wake up any pending addfd messages, as
1389                  * the notifier will do that for us, as this just looks
1390                  * like a standard reply.
1391                  */
1392                 complete(&knotif->ready);
1393         }
1394
1395         seccomp_notify_free(filter);
1396         mutex_unlock(&filter->notify_lock);
1397 }
1398
1399 static int seccomp_notify_release(struct inode *inode, struct file *file)
1400 {
1401         struct seccomp_filter *filter = file->private_data;
1402
1403         seccomp_notify_detach(filter);
1404         __put_seccomp_filter(filter);
1405         return 0;
1406 }
1407
1408 /* must be called with notif_lock held */
1409 static inline struct seccomp_knotif *
1410 find_notification(struct seccomp_filter *filter, u64 id)
1411 {
1412         struct seccomp_knotif *cur;
1413
1414         lockdep_assert_held(&filter->notify_lock);
1415
1416         list_for_each_entry(cur, &filter->notif->notifications, list) {
1417                 if (cur->id == id)
1418                         return cur;
1419         }
1420
1421         return NULL;
1422 }
1423
1424
1425 static long seccomp_notify_recv(struct seccomp_filter *filter,
1426                                 void __user *buf)
1427 {
1428         struct seccomp_knotif *knotif = NULL, *cur;
1429         struct seccomp_notif unotif;
1430         ssize_t ret;
1431
1432         /* Verify that we're not given garbage to keep struct extensible. */
1433         ret = check_zeroed_user(buf, sizeof(unotif));
1434         if (ret < 0)
1435                 return ret;
1436         if (!ret)
1437                 return -EINVAL;
1438
1439         memset(&unotif, 0, sizeof(unotif));
1440
1441         ret = down_interruptible(&filter->notif->request);
1442         if (ret < 0)
1443                 return ret;
1444
1445         mutex_lock(&filter->notify_lock);
1446         list_for_each_entry(cur, &filter->notif->notifications, list) {
1447                 if (cur->state == SECCOMP_NOTIFY_INIT) {
1448                         knotif = cur;
1449                         break;
1450                 }
1451         }
1452
1453         /*
1454          * If we didn't find a notification, it could be that the task was
1455          * interrupted by a fatal signal between the time we were woken and
1456          * when we were able to acquire the rw lock.
1457          */
1458         if (!knotif) {
1459                 ret = -ENOENT;
1460                 goto out;
1461         }
1462
1463         unotif.id = knotif->id;
1464         unotif.pid = task_pid_vnr(knotif->task);
1465         unotif.data = *(knotif->data);
1466
1467         knotif->state = SECCOMP_NOTIFY_SENT;
1468         wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1469         ret = 0;
1470 out:
1471         mutex_unlock(&filter->notify_lock);
1472
1473         if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1474                 ret = -EFAULT;
1475
1476                 /*
1477                  * Userspace screwed up. To make sure that we keep this
1478                  * notification alive, let's reset it back to INIT. It
1479                  * may have died when we released the lock, so we need to make
1480                  * sure it's still around.
1481                  */
1482                 mutex_lock(&filter->notify_lock);
1483                 knotif = find_notification(filter, unotif.id);
1484                 if (knotif) {
1485                         knotif->state = SECCOMP_NOTIFY_INIT;
1486                         up(&filter->notif->request);
1487                 }
1488                 mutex_unlock(&filter->notify_lock);
1489         }
1490
1491         return ret;
1492 }
1493
1494 static long seccomp_notify_send(struct seccomp_filter *filter,
1495                                 void __user *buf)
1496 {
1497         struct seccomp_notif_resp resp = {};
1498         struct seccomp_knotif *knotif;
1499         long ret;
1500
1501         if (copy_from_user(&resp, buf, sizeof(resp)))
1502                 return -EFAULT;
1503
1504         if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1505                 return -EINVAL;
1506
1507         if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1508             (resp.error || resp.val))
1509                 return -EINVAL;
1510
1511         ret = mutex_lock_interruptible(&filter->notify_lock);
1512         if (ret < 0)
1513                 return ret;
1514
1515         knotif = find_notification(filter, resp.id);
1516         if (!knotif) {
1517                 ret = -ENOENT;
1518                 goto out;
1519         }
1520
1521         /* Allow exactly one reply. */
1522         if (knotif->state != SECCOMP_NOTIFY_SENT) {
1523                 ret = -EINPROGRESS;
1524                 goto out;
1525         }
1526
1527         ret = 0;
1528         knotif->state = SECCOMP_NOTIFY_REPLIED;
1529         knotif->error = resp.error;
1530         knotif->val = resp.val;
1531         knotif->flags = resp.flags;
1532         complete(&knotif->ready);
1533 out:
1534         mutex_unlock(&filter->notify_lock);
1535         return ret;
1536 }
1537
1538 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1539                                     void __user *buf)
1540 {
1541         struct seccomp_knotif *knotif;
1542         u64 id;
1543         long ret;
1544
1545         if (copy_from_user(&id, buf, sizeof(id)))
1546                 return -EFAULT;
1547
1548         ret = mutex_lock_interruptible(&filter->notify_lock);
1549         if (ret < 0)
1550                 return ret;
1551
1552         knotif = find_notification(filter, id);
1553         if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1554                 ret = 0;
1555         else
1556                 ret = -ENOENT;
1557
1558         mutex_unlock(&filter->notify_lock);
1559         return ret;
1560 }
1561
1562 static long seccomp_notify_addfd(struct seccomp_filter *filter,
1563                                  struct seccomp_notif_addfd __user *uaddfd,
1564                                  unsigned int size)
1565 {
1566         struct seccomp_notif_addfd addfd;
1567         struct seccomp_knotif *knotif;
1568         struct seccomp_kaddfd kaddfd;
1569         int ret;
1570
1571         BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1572         BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1573
1574         if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1575                 return -EINVAL;
1576
1577         ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1578         if (ret)
1579                 return ret;
1580
1581         if (addfd.newfd_flags & ~O_CLOEXEC)
1582                 return -EINVAL;
1583
1584         if (addfd.flags & ~SECCOMP_ADDFD_FLAG_SETFD)
1585                 return -EINVAL;
1586
1587         if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1588                 return -EINVAL;
1589
1590         kaddfd.file = fget(addfd.srcfd);
1591         if (!kaddfd.file)
1592                 return -EBADF;
1593
1594         kaddfd.flags = addfd.newfd_flags;
1595         kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1596         kaddfd.fd = addfd.newfd;
1597         init_completion(&kaddfd.completion);
1598
1599         ret = mutex_lock_interruptible(&filter->notify_lock);
1600         if (ret < 0)
1601                 goto out;
1602
1603         knotif = find_notification(filter, addfd.id);
1604         if (!knotif) {
1605                 ret = -ENOENT;
1606                 goto out_unlock;
1607         }
1608
1609         /*
1610          * We do not want to allow for FD injection to occur before the
1611          * notification has been picked up by a userspace handler, or after
1612          * the notification has been replied to.
1613          */
1614         if (knotif->state != SECCOMP_NOTIFY_SENT) {
1615                 ret = -EINPROGRESS;
1616                 goto out_unlock;
1617         }
1618
1619         list_add(&kaddfd.list, &knotif->addfd);
1620         complete(&knotif->ready);
1621         mutex_unlock(&filter->notify_lock);
1622
1623         /* Now we wait for it to be processed or be interrupted */
1624         ret = wait_for_completion_interruptible(&kaddfd.completion);
1625         if (ret == 0) {
1626                 /*
1627                  * We had a successful completion. The other side has already
1628                  * removed us from the addfd queue, and
1629                  * wait_for_completion_interruptible has a memory barrier upon
1630                  * success that lets us read this value directly without
1631                  * locking.
1632                  */
1633                 ret = kaddfd.ret;
1634                 goto out;
1635         }
1636
1637         mutex_lock(&filter->notify_lock);
1638         /*
1639          * Even though we were woken up by a signal and not a successful
1640          * completion, a completion may have happened in the mean time.
1641          *
1642          * We need to check again if the addfd request has been handled,
1643          * and if not, we will remove it from the queue.
1644          */
1645         if (list_empty(&kaddfd.list))
1646                 ret = kaddfd.ret;
1647         else
1648                 list_del(&kaddfd.list);
1649
1650 out_unlock:
1651         mutex_unlock(&filter->notify_lock);
1652 out:
1653         fput(kaddfd.file);
1654
1655         return ret;
1656 }
1657
1658 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1659                                  unsigned long arg)
1660 {
1661         struct seccomp_filter *filter = file->private_data;
1662         void __user *buf = (void __user *)arg;
1663
1664         /* Fixed-size ioctls */
1665         switch (cmd) {
1666         case SECCOMP_IOCTL_NOTIF_RECV:
1667                 return seccomp_notify_recv(filter, buf);
1668         case SECCOMP_IOCTL_NOTIF_SEND:
1669                 return seccomp_notify_send(filter, buf);
1670         case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1671         case SECCOMP_IOCTL_NOTIF_ID_VALID:
1672                 return seccomp_notify_id_valid(filter, buf);
1673         }
1674
1675         /* Extensible Argument ioctls */
1676 #define EA_IOCTL(cmd)   ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1677         switch (EA_IOCTL(cmd)) {
1678         case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1679                 return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1680         default:
1681                 return -EINVAL;
1682         }
1683 }
1684
1685 static __poll_t seccomp_notify_poll(struct file *file,
1686                                     struct poll_table_struct *poll_tab)
1687 {
1688         struct seccomp_filter *filter = file->private_data;
1689         __poll_t ret = 0;
1690         struct seccomp_knotif *cur;
1691
1692         poll_wait(file, &filter->wqh, poll_tab);
1693
1694         if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1695                 return EPOLLERR;
1696
1697         list_for_each_entry(cur, &filter->notif->notifications, list) {
1698                 if (cur->state == SECCOMP_NOTIFY_INIT)
1699                         ret |= EPOLLIN | EPOLLRDNORM;
1700                 if (cur->state == SECCOMP_NOTIFY_SENT)
1701                         ret |= EPOLLOUT | EPOLLWRNORM;
1702                 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1703                         break;
1704         }
1705
1706         mutex_unlock(&filter->notify_lock);
1707
1708         if (refcount_read(&filter->users) == 0)
1709                 ret |= EPOLLHUP;
1710
1711         return ret;
1712 }
1713
1714 static const struct file_operations seccomp_notify_ops = {
1715         .poll = seccomp_notify_poll,
1716         .release = seccomp_notify_release,
1717         .unlocked_ioctl = seccomp_notify_ioctl,
1718         .compat_ioctl = seccomp_notify_ioctl,
1719 };
1720
1721 static struct file *init_listener(struct seccomp_filter *filter)
1722 {
1723         struct file *ret;
1724
1725         ret = ERR_PTR(-ENOMEM);
1726         filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1727         if (!filter->notif)
1728                 goto out;
1729
1730         sema_init(&filter->notif->request, 0);
1731         filter->notif->next_id = get_random_u64();
1732         INIT_LIST_HEAD(&filter->notif->notifications);
1733
1734         ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1735                                  filter, O_RDWR);
1736         if (IS_ERR(ret))
1737                 goto out_notif;
1738
1739         /* The file has a reference to it now */
1740         __get_seccomp_filter(filter);
1741
1742 out_notif:
1743         if (IS_ERR(ret))
1744                 seccomp_notify_free(filter);
1745 out:
1746         return ret;
1747 }
1748
1749 /*
1750  * Does @new_child have a listener while an ancestor also has a listener?
1751  * If so, we'll want to reject this filter.
1752  * This only has to be tested for the current process, even in the TSYNC case,
1753  * because TSYNC installs @child with the same parent on all threads.
1754  * Note that @new_child is not hooked up to its parent at this point yet, so
1755  * we use current->seccomp.filter.
1756  */
1757 static bool has_duplicate_listener(struct seccomp_filter *new_child)
1758 {
1759         struct seccomp_filter *cur;
1760
1761         /* must be protected against concurrent TSYNC */
1762         lockdep_assert_held(&current->sighand->siglock);
1763
1764         if (!new_child->notif)
1765                 return false;
1766         for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1767                 if (cur->notif)
1768                         return true;
1769         }
1770
1771         return false;
1772 }
1773
1774 /**
1775  * seccomp_set_mode_filter: internal function for setting seccomp filter
1776  * @flags:  flags to change filter behavior
1777  * @filter: struct sock_fprog containing filter
1778  *
1779  * This function may be called repeatedly to install additional filters.
1780  * Every filter successfully installed will be evaluated (in reverse order)
1781  * for each system call the task makes.
1782  *
1783  * Once current->seccomp.mode is non-zero, it may not be changed.
1784  *
1785  * Returns 0 on success or -EINVAL on failure.
1786  */
1787 static long seccomp_set_mode_filter(unsigned int flags,
1788                                     const char __user *filter)
1789 {
1790         const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1791         struct seccomp_filter *prepared = NULL;
1792         long ret = -EINVAL;
1793         int listener = -1;
1794         struct file *listener_f = NULL;
1795
1796         /* Validate flags. */
1797         if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1798                 return -EINVAL;
1799
1800         /*
1801          * In the successful case, NEW_LISTENER returns the new listener fd.
1802          * But in the failure case, TSYNC returns the thread that died. If you
1803          * combine these two flags, there's no way to tell whether something
1804          * succeeded or failed. So, let's disallow this combination if the user
1805          * has not explicitly requested no errors from TSYNC.
1806          */
1807         if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1808             (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1809             ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1810                 return -EINVAL;
1811
1812         /* Prepare the new filter before holding any locks. */
1813         prepared = seccomp_prepare_user_filter(filter);
1814         if (IS_ERR(prepared))
1815                 return PTR_ERR(prepared);
1816
1817         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1818                 listener = get_unused_fd_flags(O_CLOEXEC);
1819                 if (listener < 0) {
1820                         ret = listener;
1821                         goto out_free;
1822                 }
1823
1824                 listener_f = init_listener(prepared);
1825                 if (IS_ERR(listener_f)) {
1826                         put_unused_fd(listener);
1827                         ret = PTR_ERR(listener_f);
1828                         goto out_free;
1829                 }
1830         }
1831
1832         /*
1833          * Make sure we cannot change seccomp or nnp state via TSYNC
1834          * while another thread is in the middle of calling exec.
1835          */
1836         if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1837             mutex_lock_killable(&current->signal->cred_guard_mutex))
1838                 goto out_put_fd;
1839
1840         spin_lock_irq(&current->sighand->siglock);
1841
1842         if (!seccomp_may_assign_mode(seccomp_mode))
1843                 goto out;
1844
1845         if (has_duplicate_listener(prepared)) {
1846                 ret = -EBUSY;
1847                 goto out;
1848         }
1849
1850         ret = seccomp_attach_filter(flags, prepared);
1851         if (ret)
1852                 goto out;
1853         /* Do not free the successfully attached filter. */
1854         prepared = NULL;
1855
1856         seccomp_assign_mode(current, seccomp_mode, flags);
1857 out:
1858         spin_unlock_irq(&current->sighand->siglock);
1859         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1860                 mutex_unlock(&current->signal->cred_guard_mutex);
1861 out_put_fd:
1862         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1863                 if (ret) {
1864                         listener_f->private_data = NULL;
1865                         fput(listener_f);
1866                         put_unused_fd(listener);
1867                         seccomp_notify_detach(prepared);
1868                 } else {
1869                         fd_install(listener, listener_f);
1870                         ret = listener;
1871                 }
1872         }
1873 out_free:
1874         seccomp_filter_free(prepared);
1875         return ret;
1876 }
1877 #else
1878 static inline long seccomp_set_mode_filter(unsigned int flags,
1879                                            const char __user *filter)
1880 {
1881         return -EINVAL;
1882 }
1883 #endif
1884
1885 static long seccomp_get_action_avail(const char __user *uaction)
1886 {
1887         u32 action;
1888
1889         if (copy_from_user(&action, uaction, sizeof(action)))
1890                 return -EFAULT;
1891
1892         switch (action) {
1893         case SECCOMP_RET_KILL_PROCESS:
1894         case SECCOMP_RET_KILL_THREAD:
1895         case SECCOMP_RET_TRAP:
1896         case SECCOMP_RET_ERRNO:
1897         case SECCOMP_RET_USER_NOTIF:
1898         case SECCOMP_RET_TRACE:
1899         case SECCOMP_RET_LOG:
1900         case SECCOMP_RET_ALLOW:
1901                 break;
1902         default:
1903                 return -EOPNOTSUPP;
1904         }
1905
1906         return 0;
1907 }
1908
1909 static long seccomp_get_notif_sizes(void __user *usizes)
1910 {
1911         struct seccomp_notif_sizes sizes = {
1912                 .seccomp_notif = sizeof(struct seccomp_notif),
1913                 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1914                 .seccomp_data = sizeof(struct seccomp_data),
1915         };
1916
1917         if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1918                 return -EFAULT;
1919
1920         return 0;
1921 }
1922
1923 /* Common entry point for both prctl and syscall. */
1924 static long do_seccomp(unsigned int op, unsigned int flags,
1925                        void __user *uargs)
1926 {
1927         switch (op) {
1928         case SECCOMP_SET_MODE_STRICT:
1929                 if (flags != 0 || uargs != NULL)
1930                         return -EINVAL;
1931                 return seccomp_set_mode_strict();
1932         case SECCOMP_SET_MODE_FILTER:
1933                 return seccomp_set_mode_filter(flags, uargs);
1934         case SECCOMP_GET_ACTION_AVAIL:
1935                 if (flags != 0)
1936                         return -EINVAL;
1937
1938                 return seccomp_get_action_avail(uargs);
1939         case SECCOMP_GET_NOTIF_SIZES:
1940                 if (flags != 0)
1941                         return -EINVAL;
1942
1943                 return seccomp_get_notif_sizes(uargs);
1944         default:
1945                 return -EINVAL;
1946         }
1947 }
1948
1949 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1950                          void __user *, uargs)
1951 {
1952         return do_seccomp(op, flags, uargs);
1953 }
1954
1955 /**
1956  * prctl_set_seccomp: configures current->seccomp.mode
1957  * @seccomp_mode: requested mode to use
1958  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1959  *
1960  * Returns 0 on success or -EINVAL on failure.
1961  */
1962 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1963 {
1964         unsigned int op;
1965         void __user *uargs;
1966
1967         switch (seccomp_mode) {
1968         case SECCOMP_MODE_STRICT:
1969                 op = SECCOMP_SET_MODE_STRICT;
1970                 /*
1971                  * Setting strict mode through prctl always ignored filter,
1972                  * so make sure it is always NULL here to pass the internal
1973                  * check in do_seccomp().
1974                  */
1975                 uargs = NULL;
1976                 break;
1977         case SECCOMP_MODE_FILTER:
1978                 op = SECCOMP_SET_MODE_FILTER;
1979                 uargs = filter;
1980                 break;
1981         default:
1982                 return -EINVAL;
1983         }
1984
1985         /* prctl interface doesn't have flags, so they are always zero. */
1986         return do_seccomp(op, 0, uargs);
1987 }
1988
1989 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1990 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1991                                              unsigned long filter_off)
1992 {
1993         struct seccomp_filter *orig, *filter;
1994         unsigned long count;
1995
1996         /*
1997          * Note: this is only correct because the caller should be the (ptrace)
1998          * tracer of the task, otherwise lock_task_sighand is needed.
1999          */
2000         spin_lock_irq(&task->sighand->siglock);
2001
2002         if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2003                 spin_unlock_irq(&task->sighand->siglock);
2004                 return ERR_PTR(-EINVAL);
2005         }
2006
2007         orig = task->seccomp.filter;
2008         __get_seccomp_filter(orig);
2009         spin_unlock_irq(&task->sighand->siglock);
2010
2011         count = 0;
2012         for (filter = orig; filter; filter = filter->prev)
2013                 count++;
2014
2015         if (filter_off >= count) {
2016                 filter = ERR_PTR(-ENOENT);
2017                 goto out;
2018         }
2019
2020         count -= filter_off;
2021         for (filter = orig; filter && count > 1; filter = filter->prev)
2022                 count--;
2023
2024         if (WARN_ON(count != 1 || !filter)) {
2025                 filter = ERR_PTR(-ENOENT);
2026                 goto out;
2027         }
2028
2029         __get_seccomp_filter(filter);
2030
2031 out:
2032         __put_seccomp_filter(orig);
2033         return filter;
2034 }
2035
2036 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2037                         void __user *data)
2038 {
2039         struct seccomp_filter *filter;
2040         struct sock_fprog_kern *fprog;
2041         long ret;
2042
2043         if (!capable(CAP_SYS_ADMIN) ||
2044             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2045                 return -EACCES;
2046         }
2047
2048         filter = get_nth_filter(task, filter_off);
2049         if (IS_ERR(filter))
2050                 return PTR_ERR(filter);
2051
2052         fprog = filter->prog->orig_prog;
2053         if (!fprog) {
2054                 /* This must be a new non-cBPF filter, since we save
2055                  * every cBPF filter's orig_prog above when
2056                  * CONFIG_CHECKPOINT_RESTORE is enabled.
2057                  */
2058                 ret = -EMEDIUMTYPE;
2059                 goto out;
2060         }
2061
2062         ret = fprog->len;
2063         if (!data)
2064                 goto out;
2065
2066         if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2067                 ret = -EFAULT;
2068
2069 out:
2070         __put_seccomp_filter(filter);
2071         return ret;
2072 }
2073
2074 long seccomp_get_metadata(struct task_struct *task,
2075                           unsigned long size, void __user *data)
2076 {
2077         long ret;
2078         struct seccomp_filter *filter;
2079         struct seccomp_metadata kmd = {};
2080
2081         if (!capable(CAP_SYS_ADMIN) ||
2082             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2083                 return -EACCES;
2084         }
2085
2086         size = min_t(unsigned long, size, sizeof(kmd));
2087
2088         if (size < sizeof(kmd.filter_off))
2089                 return -EINVAL;
2090
2091         if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2092                 return -EFAULT;
2093
2094         filter = get_nth_filter(task, kmd.filter_off);
2095         if (IS_ERR(filter))
2096                 return PTR_ERR(filter);
2097
2098         if (filter->log)
2099                 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2100
2101         ret = size;
2102         if (copy_to_user(data, &kmd, size))
2103                 ret = -EFAULT;
2104
2105         __put_seccomp_filter(filter);
2106         return ret;
2107 }
2108 #endif
2109
2110 #ifdef CONFIG_SYSCTL
2111
2112 /* Human readable action names for friendly sysctl interaction */
2113 #define SECCOMP_RET_KILL_PROCESS_NAME   "kill_process"
2114 #define SECCOMP_RET_KILL_THREAD_NAME    "kill_thread"
2115 #define SECCOMP_RET_TRAP_NAME           "trap"
2116 #define SECCOMP_RET_ERRNO_NAME          "errno"
2117 #define SECCOMP_RET_USER_NOTIF_NAME     "user_notif"
2118 #define SECCOMP_RET_TRACE_NAME          "trace"
2119 #define SECCOMP_RET_LOG_NAME            "log"
2120 #define SECCOMP_RET_ALLOW_NAME          "allow"
2121
2122 static const char seccomp_actions_avail[] =
2123                                 SECCOMP_RET_KILL_PROCESS_NAME   " "
2124                                 SECCOMP_RET_KILL_THREAD_NAME    " "
2125                                 SECCOMP_RET_TRAP_NAME           " "
2126                                 SECCOMP_RET_ERRNO_NAME          " "
2127                                 SECCOMP_RET_USER_NOTIF_NAME     " "
2128                                 SECCOMP_RET_TRACE_NAME          " "
2129                                 SECCOMP_RET_LOG_NAME            " "
2130                                 SECCOMP_RET_ALLOW_NAME;
2131
2132 struct seccomp_log_name {
2133         u32             log;
2134         const char      *name;
2135 };
2136
2137 static const struct seccomp_log_name seccomp_log_names[] = {
2138         { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2139         { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2140         { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2141         { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2142         { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2143         { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2144         { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2145         { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2146         { }
2147 };
2148
2149 static bool seccomp_names_from_actions_logged(char *names, size_t size,
2150                                               u32 actions_logged,
2151                                               const char *sep)
2152 {
2153         const struct seccomp_log_name *cur;
2154         bool append_sep = false;
2155
2156         for (cur = seccomp_log_names; cur->name && size; cur++) {
2157                 ssize_t ret;
2158
2159                 if (!(actions_logged & cur->log))
2160                         continue;
2161
2162                 if (append_sep) {
2163                         ret = strscpy(names, sep, size);
2164                         if (ret < 0)
2165                                 return false;
2166
2167                         names += ret;
2168                         size -= ret;
2169                 } else
2170                         append_sep = true;
2171
2172                 ret = strscpy(names, cur->name, size);
2173                 if (ret < 0)
2174                         return false;
2175
2176                 names += ret;
2177                 size -= ret;
2178         }
2179
2180         return true;
2181 }
2182
2183 static bool seccomp_action_logged_from_name(u32 *action_logged,
2184                                             const char *name)
2185 {
2186         const struct seccomp_log_name *cur;
2187
2188         for (cur = seccomp_log_names; cur->name; cur++) {
2189                 if (!strcmp(cur->name, name)) {
2190                         *action_logged = cur->log;
2191                         return true;
2192                 }
2193         }
2194
2195         return false;
2196 }
2197
2198 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2199 {
2200         char *name;
2201
2202         *actions_logged = 0;
2203         while ((name = strsep(&names, " ")) && *name) {
2204                 u32 action_logged = 0;
2205
2206                 if (!seccomp_action_logged_from_name(&action_logged, name))
2207                         return false;
2208
2209                 *actions_logged |= action_logged;
2210         }
2211
2212         return true;
2213 }
2214
2215 static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
2216                                size_t *lenp, loff_t *ppos)
2217 {
2218         char names[sizeof(seccomp_actions_avail)];
2219         struct ctl_table table;
2220
2221         memset(names, 0, sizeof(names));
2222
2223         if (!seccomp_names_from_actions_logged(names, sizeof(names),
2224                                                seccomp_actions_logged, " "))
2225                 return -EINVAL;
2226
2227         table = *ro_table;
2228         table.data = names;
2229         table.maxlen = sizeof(names);
2230         return proc_dostring(&table, 0, buffer, lenp, ppos);
2231 }
2232
2233 static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
2234                                 size_t *lenp, loff_t *ppos, u32 *actions_logged)
2235 {
2236         char names[sizeof(seccomp_actions_avail)];
2237         struct ctl_table table;
2238         int ret;
2239
2240         if (!capable(CAP_SYS_ADMIN))
2241                 return -EPERM;
2242
2243         memset(names, 0, sizeof(names));
2244
2245         table = *ro_table;
2246         table.data = names;
2247         table.maxlen = sizeof(names);
2248         ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2249         if (ret)
2250                 return ret;
2251
2252         if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2253                 return -EINVAL;
2254
2255         if (*actions_logged & SECCOMP_LOG_ALLOW)
2256                 return -EINVAL;
2257
2258         seccomp_actions_logged = *actions_logged;
2259         return 0;
2260 }
2261
2262 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2263                                  int ret)
2264 {
2265         char names[sizeof(seccomp_actions_avail)];
2266         char old_names[sizeof(seccomp_actions_avail)];
2267         const char *new = names;
2268         const char *old = old_names;
2269
2270         if (!audit_enabled)
2271                 return;
2272
2273         memset(names, 0, sizeof(names));
2274         memset(old_names, 0, sizeof(old_names));
2275
2276         if (ret)
2277                 new = "?";
2278         else if (!actions_logged)
2279                 new = "(none)";
2280         else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2281                                                     actions_logged, ","))
2282                 new = "?";
2283
2284         if (!old_actions_logged)
2285                 old = "(none)";
2286         else if (!seccomp_names_from_actions_logged(old_names,
2287                                                     sizeof(old_names),
2288                                                     old_actions_logged, ","))
2289                 old = "?";
2290
2291         return audit_seccomp_actions_logged(new, old, !ret);
2292 }
2293
2294 static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2295                                           void *buffer, size_t *lenp,
2296                                           loff_t *ppos)
2297 {
2298         int ret;
2299
2300         if (write) {
2301                 u32 actions_logged = 0;
2302                 u32 old_actions_logged = seccomp_actions_logged;
2303
2304                 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2305                                            &actions_logged);
2306                 audit_actions_logged(actions_logged, old_actions_logged, ret);
2307         } else
2308                 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2309
2310         return ret;
2311 }
2312
2313 static struct ctl_path seccomp_sysctl_path[] = {
2314         { .procname = "kernel", },
2315         { .procname = "seccomp", },
2316         { }
2317 };
2318
2319 static struct ctl_table seccomp_sysctl_table[] = {
2320         {
2321                 .procname       = "actions_avail",
2322                 .data           = (void *) &seccomp_actions_avail,
2323                 .maxlen         = sizeof(seccomp_actions_avail),
2324                 .mode           = 0444,
2325                 .proc_handler   = proc_dostring,
2326         },
2327         {
2328                 .procname       = "actions_logged",
2329                 .mode           = 0644,
2330                 .proc_handler   = seccomp_actions_logged_handler,
2331         },
2332         { }
2333 };
2334
2335 static int __init seccomp_sysctl_init(void)
2336 {
2337         struct ctl_table_header *hdr;
2338
2339         hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
2340         if (!hdr)
2341                 pr_warn("sysctl registration failed\n");
2342         else
2343                 kmemleak_not_leak(hdr);
2344
2345         return 0;
2346 }
2347
2348 device_initcall(seccomp_sysctl_init)
2349
2350 #endif /* CONFIG_SYSCTL */
2351
2352 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
2353 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2354 static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2355                                         const void *bitmap, size_t bitmap_size)
2356 {
2357         int nr;
2358
2359         for (nr = 0; nr < bitmap_size; nr++) {
2360                 bool cached = test_bit(nr, bitmap);
2361                 char *status = cached ? "ALLOW" : "FILTER";
2362
2363                 seq_printf(m, "%s %d %s\n", name, nr, status);
2364         }
2365 }
2366
2367 int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2368                            struct pid *pid, struct task_struct *task)
2369 {
2370         struct seccomp_filter *f;
2371         unsigned long flags;
2372
2373         /*
2374          * We don't want some sandboxed process to know what their seccomp
2375          * filters consist of.
2376          */
2377         if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2378                 return -EACCES;
2379
2380         if (!lock_task_sighand(task, &flags))
2381                 return -ESRCH;
2382
2383         f = READ_ONCE(task->seccomp.filter);
2384         if (!f) {
2385                 unlock_task_sighand(task, &flags);
2386                 return 0;
2387         }
2388
2389         /* prevent filter from being freed while we are printing it */
2390         __get_seccomp_filter(f);
2391         unlock_task_sighand(task, &flags);
2392
2393         proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2394                                     f->cache.allow_native,
2395                                     SECCOMP_ARCH_NATIVE_NR);
2396
2397 #ifdef SECCOMP_ARCH_COMPAT
2398         proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2399                                     f->cache.allow_compat,
2400                                     SECCOMP_ARCH_COMPAT_NR);
2401 #endif /* SECCOMP_ARCH_COMPAT */
2402
2403         __put_seccomp_filter(f);
2404         return 0;
2405 }
2406 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */