15b6be97fc09a3455695d6b97f79f282db3f2a2d
[sfrench/cifs-2.6.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
17 #include <linux/refcount.h>
18 #include <linux/audit.h>
19 #include <linux/compat.h>
20 #include <linux/coredump.h>
21 #include <linux/kmemleak.h>
22 #include <linux/nospec.h>
23 #include <linux/prctl.h>
24 #include <linux/sched.h>
25 #include <linux/sched/task_stack.h>
26 #include <linux/seccomp.h>
27 #include <linux/slab.h>
28 #include <linux/syscalls.h>
29 #include <linux/sysctl.h>
30
31 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
32 #include <asm/syscall.h>
33 #endif
34
35 #ifdef CONFIG_SECCOMP_FILTER
36 #include <linux/file.h>
37 #include <linux/filter.h>
38 #include <linux/pid.h>
39 #include <linux/ptrace.h>
40 #include <linux/security.h>
41 #include <linux/tracehook.h>
42 #include <linux/uaccess.h>
43 #include <linux/anon_inodes.h>
44
45 enum notify_state {
46         SECCOMP_NOTIFY_INIT,
47         SECCOMP_NOTIFY_SENT,
48         SECCOMP_NOTIFY_REPLIED,
49 };
50
51 struct seccomp_knotif {
52         /* The struct pid of the task whose filter triggered the notification */
53         struct task_struct *task;
54
55         /* The "cookie" for this request; this is unique for this filter. */
56         u64 id;
57
58         /*
59          * The seccomp data. This pointer is valid the entire time this
60          * notification is active, since it comes from __seccomp_filter which
61          * eclipses the entire lifecycle here.
62          */
63         const struct seccomp_data *data;
64
65         /*
66          * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
67          * struct seccomp_knotif is created and starts out in INIT. Once the
68          * handler reads the notification off of an FD, it transitions to SENT.
69          * If a signal is received the state transitions back to INIT and
70          * another message is sent. When the userspace handler replies, state
71          * transitions to REPLIED.
72          */
73         enum notify_state state;
74
75         /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
76         int error;
77         long val;
78
79         /* Signals when this has entered SECCOMP_NOTIFY_REPLIED */
80         struct completion ready;
81
82         struct list_head list;
83 };
84
85 /**
86  * struct notification - container for seccomp userspace notifications. Since
87  * most seccomp filters will not have notification listeners attached and this
88  * structure is fairly large, we store the notification-specific stuff in a
89  * separate structure.
90  *
91  * @request: A semaphore that users of this notification can wait on for
92  *           changes. Actual reads and writes are still controlled with
93  *           filter->notify_lock.
94  * @next_id: The id of the next request.
95  * @notifications: A list of struct seccomp_knotif elements.
96  * @wqh: A wait queue for poll.
97  */
98 struct notification {
99         struct semaphore request;
100         u64 next_id;
101         struct list_head notifications;
102         wait_queue_head_t wqh;
103 };
104
105 /**
106  * struct seccomp_filter - container for seccomp BPF programs
107  *
108  * @usage: reference count to manage the object lifetime.
109  *         get/put helpers should be used when accessing an instance
110  *         outside of a lifetime-guarded section.  In general, this
111  *         is only needed for handling filters shared across tasks.
112  * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
113  * @prev: points to a previously installed, or inherited, filter
114  * @prog: the BPF program to evaluate
115  * @notif: the struct that holds all notification related information
116  * @notify_lock: A lock for all notification-related accesses.
117  *
118  * seccomp_filter objects are organized in a tree linked via the @prev
119  * pointer.  For any task, it appears to be a singly-linked list starting
120  * with current->seccomp.filter, the most recently attached or inherited filter.
121  * However, multiple filters may share a @prev node, by way of fork(), which
122  * results in a unidirectional tree existing in memory.  This is similar to
123  * how namespaces work.
124  *
125  * seccomp_filter objects should never be modified after being attached
126  * to a task_struct (other than @usage).
127  */
128 struct seccomp_filter {
129         refcount_t usage;
130         bool log;
131         struct seccomp_filter *prev;
132         struct bpf_prog *prog;
133         struct notification *notif;
134         struct mutex notify_lock;
135 };
136
137 /* Limit any path through the tree to 256KB worth of instructions. */
138 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
139
140 /*
141  * Endianness is explicitly ignored and left for BPF program authors to manage
142  * as per the specific architecture.
143  */
144 static void populate_seccomp_data(struct seccomp_data *sd)
145 {
146         struct task_struct *task = current;
147         struct pt_regs *regs = task_pt_regs(task);
148         unsigned long args[6];
149
150         sd->nr = syscall_get_nr(task, regs);
151         sd->arch = syscall_get_arch();
152         syscall_get_arguments(task, regs, 0, 6, args);
153         sd->args[0] = args[0];
154         sd->args[1] = args[1];
155         sd->args[2] = args[2];
156         sd->args[3] = args[3];
157         sd->args[4] = args[4];
158         sd->args[5] = args[5];
159         sd->instruction_pointer = KSTK_EIP(task);
160 }
161
162 /**
163  *      seccomp_check_filter - verify seccomp filter code
164  *      @filter: filter to verify
165  *      @flen: length of filter
166  *
167  * Takes a previously checked filter (by bpf_check_classic) and
168  * redirects all filter code that loads struct sk_buff data
169  * and related data through seccomp_bpf_load.  It also
170  * enforces length and alignment checking of those loads.
171  *
172  * Returns 0 if the rule set is legal or -EINVAL if not.
173  */
174 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
175 {
176         int pc;
177         for (pc = 0; pc < flen; pc++) {
178                 struct sock_filter *ftest = &filter[pc];
179                 u16 code = ftest->code;
180                 u32 k = ftest->k;
181
182                 switch (code) {
183                 case BPF_LD | BPF_W | BPF_ABS:
184                         ftest->code = BPF_LDX | BPF_W | BPF_ABS;
185                         /* 32-bit aligned and not out of bounds. */
186                         if (k >= sizeof(struct seccomp_data) || k & 3)
187                                 return -EINVAL;
188                         continue;
189                 case BPF_LD | BPF_W | BPF_LEN:
190                         ftest->code = BPF_LD | BPF_IMM;
191                         ftest->k = sizeof(struct seccomp_data);
192                         continue;
193                 case BPF_LDX | BPF_W | BPF_LEN:
194                         ftest->code = BPF_LDX | BPF_IMM;
195                         ftest->k = sizeof(struct seccomp_data);
196                         continue;
197                 /* Explicitly include allowed calls. */
198                 case BPF_RET | BPF_K:
199                 case BPF_RET | BPF_A:
200                 case BPF_ALU | BPF_ADD | BPF_K:
201                 case BPF_ALU | BPF_ADD | BPF_X:
202                 case BPF_ALU | BPF_SUB | BPF_K:
203                 case BPF_ALU | BPF_SUB | BPF_X:
204                 case BPF_ALU | BPF_MUL | BPF_K:
205                 case BPF_ALU | BPF_MUL | BPF_X:
206                 case BPF_ALU | BPF_DIV | BPF_K:
207                 case BPF_ALU | BPF_DIV | BPF_X:
208                 case BPF_ALU | BPF_AND | BPF_K:
209                 case BPF_ALU | BPF_AND | BPF_X:
210                 case BPF_ALU | BPF_OR | BPF_K:
211                 case BPF_ALU | BPF_OR | BPF_X:
212                 case BPF_ALU | BPF_XOR | BPF_K:
213                 case BPF_ALU | BPF_XOR | BPF_X:
214                 case BPF_ALU | BPF_LSH | BPF_K:
215                 case BPF_ALU | BPF_LSH | BPF_X:
216                 case BPF_ALU | BPF_RSH | BPF_K:
217                 case BPF_ALU | BPF_RSH | BPF_X:
218                 case BPF_ALU | BPF_NEG:
219                 case BPF_LD | BPF_IMM:
220                 case BPF_LDX | BPF_IMM:
221                 case BPF_MISC | BPF_TAX:
222                 case BPF_MISC | BPF_TXA:
223                 case BPF_LD | BPF_MEM:
224                 case BPF_LDX | BPF_MEM:
225                 case BPF_ST:
226                 case BPF_STX:
227                 case BPF_JMP | BPF_JA:
228                 case BPF_JMP | BPF_JEQ | BPF_K:
229                 case BPF_JMP | BPF_JEQ | BPF_X:
230                 case BPF_JMP | BPF_JGE | BPF_K:
231                 case BPF_JMP | BPF_JGE | BPF_X:
232                 case BPF_JMP | BPF_JGT | BPF_K:
233                 case BPF_JMP | BPF_JGT | BPF_X:
234                 case BPF_JMP | BPF_JSET | BPF_K:
235                 case BPF_JMP | BPF_JSET | BPF_X:
236                         continue;
237                 default:
238                         return -EINVAL;
239                 }
240         }
241         return 0;
242 }
243
244 /**
245  * seccomp_run_filters - evaluates all seccomp filters against @sd
246  * @sd: optional seccomp data to be passed to filters
247  * @match: stores struct seccomp_filter that resulted in the return value,
248  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
249  *         be unchanged.
250  *
251  * Returns valid seccomp BPF response codes.
252  */
253 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
254 static u32 seccomp_run_filters(const struct seccomp_data *sd,
255                                struct seccomp_filter **match)
256 {
257         u32 ret = SECCOMP_RET_ALLOW;
258         /* Make sure cross-thread synced filter points somewhere sane. */
259         struct seccomp_filter *f =
260                         READ_ONCE(current->seccomp.filter);
261
262         /* Ensure unexpected behavior doesn't result in failing open. */
263         if (WARN_ON(f == NULL))
264                 return SECCOMP_RET_KILL_PROCESS;
265
266         /*
267          * All filters in the list are evaluated and the lowest BPF return
268          * value always takes priority (ignoring the DATA).
269          */
270         for (; f; f = f->prev) {
271                 u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
272
273                 if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
274                         ret = cur_ret;
275                         *match = f;
276                 }
277         }
278         return ret;
279 }
280 #endif /* CONFIG_SECCOMP_FILTER */
281
282 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
283 {
284         assert_spin_locked(&current->sighand->siglock);
285
286         if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
287                 return false;
288
289         return true;
290 }
291
292 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
293
294 static inline void seccomp_assign_mode(struct task_struct *task,
295                                        unsigned long seccomp_mode,
296                                        unsigned long flags)
297 {
298         assert_spin_locked(&task->sighand->siglock);
299
300         task->seccomp.mode = seccomp_mode;
301         /*
302          * Make sure TIF_SECCOMP cannot be set before the mode (and
303          * filter) is set.
304          */
305         smp_mb__before_atomic();
306         /* Assume default seccomp processes want spec flaw mitigation. */
307         if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
308                 arch_seccomp_spec_mitigate(task);
309         set_tsk_thread_flag(task, TIF_SECCOMP);
310 }
311
312 #ifdef CONFIG_SECCOMP_FILTER
313 /* Returns 1 if the parent is an ancestor of the child. */
314 static int is_ancestor(struct seccomp_filter *parent,
315                        struct seccomp_filter *child)
316 {
317         /* NULL is the root ancestor. */
318         if (parent == NULL)
319                 return 1;
320         for (; child; child = child->prev)
321                 if (child == parent)
322                         return 1;
323         return 0;
324 }
325
326 /**
327  * seccomp_can_sync_threads: checks if all threads can be synchronized
328  *
329  * Expects sighand and cred_guard_mutex locks to be held.
330  *
331  * Returns 0 on success, -ve on error, or the pid of a thread which was
332  * either not in the correct seccomp mode or it did not have an ancestral
333  * seccomp filter.
334  */
335 static inline pid_t seccomp_can_sync_threads(void)
336 {
337         struct task_struct *thread, *caller;
338
339         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
340         assert_spin_locked(&current->sighand->siglock);
341
342         /* Validate all threads being eligible for synchronization. */
343         caller = current;
344         for_each_thread(caller, thread) {
345                 pid_t failed;
346
347                 /* Skip current, since it is initiating the sync. */
348                 if (thread == caller)
349                         continue;
350
351                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
352                     (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
353                      is_ancestor(thread->seccomp.filter,
354                                  caller->seccomp.filter)))
355                         continue;
356
357                 /* Return the first thread that cannot be synchronized. */
358                 failed = task_pid_vnr(thread);
359                 /* If the pid cannot be resolved, then return -ESRCH */
360                 if (WARN_ON(failed == 0))
361                         failed = -ESRCH;
362                 return failed;
363         }
364
365         return 0;
366 }
367
368 /**
369  * seccomp_sync_threads: sets all threads to use current's filter
370  *
371  * Expects sighand and cred_guard_mutex locks to be held, and for
372  * seccomp_can_sync_threads() to have returned success already
373  * without dropping the locks.
374  *
375  */
376 static inline void seccomp_sync_threads(unsigned long flags)
377 {
378         struct task_struct *thread, *caller;
379
380         BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
381         assert_spin_locked(&current->sighand->siglock);
382
383         /* Synchronize all threads. */
384         caller = current;
385         for_each_thread(caller, thread) {
386                 /* Skip current, since it needs no changes. */
387                 if (thread == caller)
388                         continue;
389
390                 /* Get a task reference for the new leaf node. */
391                 get_seccomp_filter(caller);
392                 /*
393                  * Drop the task reference to the shared ancestor since
394                  * current's path will hold a reference.  (This also
395                  * allows a put before the assignment.)
396                  */
397                 put_seccomp_filter(thread);
398                 smp_store_release(&thread->seccomp.filter,
399                                   caller->seccomp.filter);
400
401                 /*
402                  * Don't let an unprivileged task work around
403                  * the no_new_privs restriction by creating
404                  * a thread that sets it up, enters seccomp,
405                  * then dies.
406                  */
407                 if (task_no_new_privs(caller))
408                         task_set_no_new_privs(thread);
409
410                 /*
411                  * Opt the other thread into seccomp if needed.
412                  * As threads are considered to be trust-realm
413                  * equivalent (see ptrace_may_access), it is safe to
414                  * allow one thread to transition the other.
415                  */
416                 if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
417                         seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
418                                             flags);
419         }
420 }
421
422 /**
423  * seccomp_prepare_filter: Prepares a seccomp filter for use.
424  * @fprog: BPF program to install
425  *
426  * Returns filter on success or an ERR_PTR on failure.
427  */
428 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
429 {
430         struct seccomp_filter *sfilter;
431         int ret;
432         const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE);
433
434         if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
435                 return ERR_PTR(-EINVAL);
436
437         BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
438
439         /*
440          * Installing a seccomp filter requires that the task has
441          * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
442          * This avoids scenarios where unprivileged tasks can affect the
443          * behavior of privileged children.
444          */
445         if (!task_no_new_privs(current) &&
446             security_capable_noaudit(current_cred(), current_user_ns(),
447                                      CAP_SYS_ADMIN) != 0)
448                 return ERR_PTR(-EACCES);
449
450         /* Allocate a new seccomp_filter */
451         sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
452         if (!sfilter)
453                 return ERR_PTR(-ENOMEM);
454
455         mutex_init(&sfilter->notify_lock);
456         ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
457                                         seccomp_check_filter, save_orig);
458         if (ret < 0) {
459                 kfree(sfilter);
460                 return ERR_PTR(ret);
461         }
462
463         refcount_set(&sfilter->usage, 1);
464
465         return sfilter;
466 }
467
468 /**
469  * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
470  * @user_filter: pointer to the user data containing a sock_fprog.
471  *
472  * Returns 0 on success and non-zero otherwise.
473  */
474 static struct seccomp_filter *
475 seccomp_prepare_user_filter(const char __user *user_filter)
476 {
477         struct sock_fprog fprog;
478         struct seccomp_filter *filter = ERR_PTR(-EFAULT);
479
480 #ifdef CONFIG_COMPAT
481         if (in_compat_syscall()) {
482                 struct compat_sock_fprog fprog32;
483                 if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
484                         goto out;
485                 fprog.len = fprog32.len;
486                 fprog.filter = compat_ptr(fprog32.filter);
487         } else /* falls through to the if below. */
488 #endif
489         if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
490                 goto out;
491         filter = seccomp_prepare_filter(&fprog);
492 out:
493         return filter;
494 }
495
496 /**
497  * seccomp_attach_filter: validate and attach filter
498  * @flags:  flags to change filter behavior
499  * @filter: seccomp filter to add to the current process
500  *
501  * Caller must be holding current->sighand->siglock lock.
502  *
503  * Returns 0 on success, -ve on error.
504  */
505 static long seccomp_attach_filter(unsigned int flags,
506                                   struct seccomp_filter *filter)
507 {
508         unsigned long total_insns;
509         struct seccomp_filter *walker;
510
511         assert_spin_locked(&current->sighand->siglock);
512
513         /* Validate resulting filter length. */
514         total_insns = filter->prog->len;
515         for (walker = current->seccomp.filter; walker; walker = walker->prev)
516                 total_insns += walker->prog->len + 4;  /* 4 instr penalty */
517         if (total_insns > MAX_INSNS_PER_PATH)
518                 return -ENOMEM;
519
520         /* If thread sync has been requested, check that it is possible. */
521         if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
522                 int ret;
523
524                 ret = seccomp_can_sync_threads();
525                 if (ret)
526                         return ret;
527         }
528
529         /* Set log flag, if present. */
530         if (flags & SECCOMP_FILTER_FLAG_LOG)
531                 filter->log = true;
532
533         /*
534          * If there is an existing filter, make it the prev and don't drop its
535          * task reference.
536          */
537         filter->prev = current->seccomp.filter;
538         current->seccomp.filter = filter;
539
540         /* Now that the new filter is in place, synchronize to all threads. */
541         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
542                 seccomp_sync_threads(flags);
543
544         return 0;
545 }
546
547 static void __get_seccomp_filter(struct seccomp_filter *filter)
548 {
549         refcount_inc(&filter->usage);
550 }
551
552 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
553 void get_seccomp_filter(struct task_struct *tsk)
554 {
555         struct seccomp_filter *orig = tsk->seccomp.filter;
556         if (!orig)
557                 return;
558         __get_seccomp_filter(orig);
559 }
560
561 static inline void seccomp_filter_free(struct seccomp_filter *filter)
562 {
563         if (filter) {
564                 bpf_prog_destroy(filter->prog);
565                 kfree(filter);
566         }
567 }
568
569 static void __put_seccomp_filter(struct seccomp_filter *orig)
570 {
571         /* Clean up single-reference branches iteratively. */
572         while (orig && refcount_dec_and_test(&orig->usage)) {
573                 struct seccomp_filter *freeme = orig;
574                 orig = orig->prev;
575                 seccomp_filter_free(freeme);
576         }
577 }
578
579 /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
580 void put_seccomp_filter(struct task_struct *tsk)
581 {
582         __put_seccomp_filter(tsk->seccomp.filter);
583 }
584
585 static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
586 {
587         clear_siginfo(info);
588         info->si_signo = SIGSYS;
589         info->si_code = SYS_SECCOMP;
590         info->si_call_addr = (void __user *)KSTK_EIP(current);
591         info->si_errno = reason;
592         info->si_arch = syscall_get_arch();
593         info->si_syscall = syscall;
594 }
595
596 /**
597  * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
598  * @syscall: syscall number to send to userland
599  * @reason: filter-supplied reason code to send to userland (via si_errno)
600  *
601  * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
602  */
603 static void seccomp_send_sigsys(int syscall, int reason)
604 {
605         struct kernel_siginfo info;
606         seccomp_init_siginfo(&info, syscall, reason);
607         force_sig_info(SIGSYS, &info, current);
608 }
609 #endif  /* CONFIG_SECCOMP_FILTER */
610
611 /* For use with seccomp_actions_logged */
612 #define SECCOMP_LOG_KILL_PROCESS        (1 << 0)
613 #define SECCOMP_LOG_KILL_THREAD         (1 << 1)
614 #define SECCOMP_LOG_TRAP                (1 << 2)
615 #define SECCOMP_LOG_ERRNO               (1 << 3)
616 #define SECCOMP_LOG_TRACE               (1 << 4)
617 #define SECCOMP_LOG_LOG                 (1 << 5)
618 #define SECCOMP_LOG_ALLOW               (1 << 6)
619 #define SECCOMP_LOG_USER_NOTIF          (1 << 7)
620
621 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
622                                     SECCOMP_LOG_KILL_THREAD  |
623                                     SECCOMP_LOG_TRAP  |
624                                     SECCOMP_LOG_ERRNO |
625                                     SECCOMP_LOG_USER_NOTIF |
626                                     SECCOMP_LOG_TRACE |
627                                     SECCOMP_LOG_LOG;
628
629 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
630                                bool requested)
631 {
632         bool log = false;
633
634         switch (action) {
635         case SECCOMP_RET_ALLOW:
636                 break;
637         case SECCOMP_RET_TRAP:
638                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
639                 break;
640         case SECCOMP_RET_ERRNO:
641                 log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
642                 break;
643         case SECCOMP_RET_TRACE:
644                 log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
645                 break;
646         case SECCOMP_RET_USER_NOTIF:
647                 log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
648                 break;
649         case SECCOMP_RET_LOG:
650                 log = seccomp_actions_logged & SECCOMP_LOG_LOG;
651                 break;
652         case SECCOMP_RET_KILL_THREAD:
653                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
654                 break;
655         case SECCOMP_RET_KILL_PROCESS:
656         default:
657                 log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
658         }
659
660         /*
661          * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
662          * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
663          * any action from being logged by removing the action name from the
664          * seccomp_actions_logged sysctl.
665          */
666         if (!log)
667                 return;
668
669         audit_seccomp(syscall, signr, action);
670 }
671
672 /*
673  * Secure computing mode 1 allows only read/write/exit/sigreturn.
674  * To be fully secure this must be combined with rlimit
675  * to limit the stack allocations too.
676  */
677 static const int mode1_syscalls[] = {
678         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
679         0, /* null terminated */
680 };
681
682 static void __secure_computing_strict(int this_syscall)
683 {
684         const int *syscall_whitelist = mode1_syscalls;
685 #ifdef CONFIG_COMPAT
686         if (in_compat_syscall())
687                 syscall_whitelist = get_compat_mode1_syscalls();
688 #endif
689         do {
690                 if (*syscall_whitelist == this_syscall)
691                         return;
692         } while (*++syscall_whitelist);
693
694 #ifdef SECCOMP_DEBUG
695         dump_stack();
696 #endif
697         seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
698         do_exit(SIGKILL);
699 }
700
701 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
702 void secure_computing_strict(int this_syscall)
703 {
704         int mode = current->seccomp.mode;
705
706         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
707             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
708                 return;
709
710         if (mode == SECCOMP_MODE_DISABLED)
711                 return;
712         else if (mode == SECCOMP_MODE_STRICT)
713                 __secure_computing_strict(this_syscall);
714         else
715                 BUG();
716 }
717 #else
718
719 #ifdef CONFIG_SECCOMP_FILTER
720 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
721 {
722         /*
723          * Note: overflow is ok here, the id just needs to be unique per
724          * filter.
725          */
726         lockdep_assert_held(&filter->notify_lock);
727         return filter->notif->next_id++;
728 }
729
730 static void seccomp_do_user_notification(int this_syscall,
731                                          struct seccomp_filter *match,
732                                          const struct seccomp_data *sd)
733 {
734         int err;
735         long ret = 0;
736         struct seccomp_knotif n = {};
737
738         mutex_lock(&match->notify_lock);
739         err = -ENOSYS;
740         if (!match->notif)
741                 goto out;
742
743         n.task = current;
744         n.state = SECCOMP_NOTIFY_INIT;
745         n.data = sd;
746         n.id = seccomp_next_notify_id(match);
747         init_completion(&n.ready);
748         list_add(&n.list, &match->notif->notifications);
749
750         up(&match->notif->request);
751         wake_up_poll(&match->notif->wqh, EPOLLIN | EPOLLRDNORM);
752         mutex_unlock(&match->notify_lock);
753
754         /*
755          * This is where we wait for a reply from userspace.
756          */
757         err = wait_for_completion_interruptible(&n.ready);
758         mutex_lock(&match->notify_lock);
759         if (err == 0) {
760                 ret = n.val;
761                 err = n.error;
762         }
763
764         /*
765          * Note that it's possible the listener died in between the time when
766          * we were notified of a respons (or a signal) and when we were able to
767          * re-acquire the lock, so only delete from the list if the
768          * notification actually exists.
769          *
770          * Also note that this test is only valid because there's no way to
771          * *reattach* to a notifier right now. If one is added, we'll need to
772          * keep track of the notif itself and make sure they match here.
773          */
774         if (match->notif)
775                 list_del(&n.list);
776 out:
777         mutex_unlock(&match->notify_lock);
778         syscall_set_return_value(current, task_pt_regs(current),
779                                  err, ret);
780 }
781
782 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
783                             const bool recheck_after_trace)
784 {
785         u32 filter_ret, action;
786         struct seccomp_filter *match = NULL;
787         int data;
788         struct seccomp_data sd_local;
789
790         /*
791          * Make sure that any changes to mode from another thread have
792          * been seen after TIF_SECCOMP was seen.
793          */
794         rmb();
795
796         if (!sd) {
797                 populate_seccomp_data(&sd_local);
798                 sd = &sd_local;
799         }
800
801         filter_ret = seccomp_run_filters(sd, &match);
802         data = filter_ret & SECCOMP_RET_DATA;
803         action = filter_ret & SECCOMP_RET_ACTION_FULL;
804
805         switch (action) {
806         case SECCOMP_RET_ERRNO:
807                 /* Set low-order bits as an errno, capped at MAX_ERRNO. */
808                 if (data > MAX_ERRNO)
809                         data = MAX_ERRNO;
810                 syscall_set_return_value(current, task_pt_regs(current),
811                                          -data, 0);
812                 goto skip;
813
814         case SECCOMP_RET_TRAP:
815                 /* Show the handler the original registers. */
816                 syscall_rollback(current, task_pt_regs(current));
817                 /* Let the filter pass back 16 bits of data. */
818                 seccomp_send_sigsys(this_syscall, data);
819                 goto skip;
820
821         case SECCOMP_RET_TRACE:
822                 /* We've been put in this state by the ptracer already. */
823                 if (recheck_after_trace)
824                         return 0;
825
826                 /* ENOSYS these calls if there is no tracer attached. */
827                 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
828                         syscall_set_return_value(current,
829                                                  task_pt_regs(current),
830                                                  -ENOSYS, 0);
831                         goto skip;
832                 }
833
834                 /* Allow the BPF to provide the event message */
835                 ptrace_event(PTRACE_EVENT_SECCOMP, data);
836                 /*
837                  * The delivery of a fatal signal during event
838                  * notification may silently skip tracer notification,
839                  * which could leave us with a potentially unmodified
840                  * syscall that the tracer would have liked to have
841                  * changed. Since the process is about to die, we just
842                  * force the syscall to be skipped and let the signal
843                  * kill the process and correctly handle any tracer exit
844                  * notifications.
845                  */
846                 if (fatal_signal_pending(current))
847                         goto skip;
848                 /* Check if the tracer forced the syscall to be skipped. */
849                 this_syscall = syscall_get_nr(current, task_pt_regs(current));
850                 if (this_syscall < 0)
851                         goto skip;
852
853                 /*
854                  * Recheck the syscall, since it may have changed. This
855                  * intentionally uses a NULL struct seccomp_data to force
856                  * a reload of all registers. This does not goto skip since
857                  * a skip would have already been reported.
858                  */
859                 if (__seccomp_filter(this_syscall, NULL, true))
860                         return -1;
861
862                 return 0;
863
864         case SECCOMP_RET_USER_NOTIF:
865                 seccomp_do_user_notification(this_syscall, match, sd);
866                 goto skip;
867
868         case SECCOMP_RET_LOG:
869                 seccomp_log(this_syscall, 0, action, true);
870                 return 0;
871
872         case SECCOMP_RET_ALLOW:
873                 /*
874                  * Note that the "match" filter will always be NULL for
875                  * this action since SECCOMP_RET_ALLOW is the starting
876                  * state in seccomp_run_filters().
877                  */
878                 return 0;
879
880         case SECCOMP_RET_KILL_THREAD:
881         case SECCOMP_RET_KILL_PROCESS:
882         default:
883                 seccomp_log(this_syscall, SIGSYS, action, true);
884                 /* Dump core only if this is the last remaining thread. */
885                 if (action == SECCOMP_RET_KILL_PROCESS ||
886                     get_nr_threads(current) == 1) {
887                         kernel_siginfo_t info;
888
889                         /* Show the original registers in the dump. */
890                         syscall_rollback(current, task_pt_regs(current));
891                         /* Trigger a manual coredump since do_exit skips it. */
892                         seccomp_init_siginfo(&info, this_syscall, data);
893                         do_coredump(&info);
894                 }
895                 if (action == SECCOMP_RET_KILL_PROCESS)
896                         do_group_exit(SIGSYS);
897                 else
898                         do_exit(SIGSYS);
899         }
900
901         unreachable();
902
903 skip:
904         seccomp_log(this_syscall, 0, action, match ? match->log : false);
905         return -1;
906 }
907 #else
908 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
909                             const bool recheck_after_trace)
910 {
911         BUG();
912 }
913 #endif
914
915 int __secure_computing(const struct seccomp_data *sd)
916 {
917         int mode = current->seccomp.mode;
918         int this_syscall;
919
920         if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
921             unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
922                 return 0;
923
924         this_syscall = sd ? sd->nr :
925                 syscall_get_nr(current, task_pt_regs(current));
926
927         switch (mode) {
928         case SECCOMP_MODE_STRICT:
929                 __secure_computing_strict(this_syscall);  /* may call do_exit */
930                 return 0;
931         case SECCOMP_MODE_FILTER:
932                 return __seccomp_filter(this_syscall, sd, false);
933         default:
934                 BUG();
935         }
936 }
937 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
938
939 long prctl_get_seccomp(void)
940 {
941         return current->seccomp.mode;
942 }
943
944 /**
945  * seccomp_set_mode_strict: internal function for setting strict seccomp
946  *
947  * Once current->seccomp.mode is non-zero, it may not be changed.
948  *
949  * Returns 0 on success or -EINVAL on failure.
950  */
951 static long seccomp_set_mode_strict(void)
952 {
953         const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
954         long ret = -EINVAL;
955
956         spin_lock_irq(&current->sighand->siglock);
957
958         if (!seccomp_may_assign_mode(seccomp_mode))
959                 goto out;
960
961 #ifdef TIF_NOTSC
962         disable_TSC();
963 #endif
964         seccomp_assign_mode(current, seccomp_mode, 0);
965         ret = 0;
966
967 out:
968         spin_unlock_irq(&current->sighand->siglock);
969
970         return ret;
971 }
972
973 #ifdef CONFIG_SECCOMP_FILTER
974 static int seccomp_notify_release(struct inode *inode, struct file *file)
975 {
976         struct seccomp_filter *filter = file->private_data;
977         struct seccomp_knotif *knotif;
978
979         mutex_lock(&filter->notify_lock);
980
981         /*
982          * If this file is being closed because e.g. the task who owned it
983          * died, let's wake everyone up who was waiting on us.
984          */
985         list_for_each_entry(knotif, &filter->notif->notifications, list) {
986                 if (knotif->state == SECCOMP_NOTIFY_REPLIED)
987                         continue;
988
989                 knotif->state = SECCOMP_NOTIFY_REPLIED;
990                 knotif->error = -ENOSYS;
991                 knotif->val = 0;
992
993                 complete(&knotif->ready);
994         }
995
996         kfree(filter->notif);
997         filter->notif = NULL;
998         mutex_unlock(&filter->notify_lock);
999         __put_seccomp_filter(filter);
1000         return 0;
1001 }
1002
1003 static long seccomp_notify_recv(struct seccomp_filter *filter,
1004                                 void __user *buf)
1005 {
1006         struct seccomp_knotif *knotif = NULL, *cur;
1007         struct seccomp_notif unotif;
1008         ssize_t ret;
1009
1010         memset(&unotif, 0, sizeof(unotif));
1011
1012         ret = down_interruptible(&filter->notif->request);
1013         if (ret < 0)
1014                 return ret;
1015
1016         mutex_lock(&filter->notify_lock);
1017         list_for_each_entry(cur, &filter->notif->notifications, list) {
1018                 if (cur->state == SECCOMP_NOTIFY_INIT) {
1019                         knotif = cur;
1020                         break;
1021                 }
1022         }
1023
1024         /*
1025          * If we didn't find a notification, it could be that the task was
1026          * interrupted by a fatal signal between the time we were woken and
1027          * when we were able to acquire the rw lock.
1028          */
1029         if (!knotif) {
1030                 ret = -ENOENT;
1031                 goto out;
1032         }
1033
1034         unotif.id = knotif->id;
1035         unotif.pid = task_pid_vnr(knotif->task);
1036         unotif.data = *(knotif->data);
1037
1038         knotif->state = SECCOMP_NOTIFY_SENT;
1039         wake_up_poll(&filter->notif->wqh, EPOLLOUT | EPOLLWRNORM);
1040         ret = 0;
1041 out:
1042         mutex_unlock(&filter->notify_lock);
1043
1044         if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1045                 ret = -EFAULT;
1046
1047                 /*
1048                  * Userspace screwed up. To make sure that we keep this
1049                  * notification alive, let's reset it back to INIT. It
1050                  * may have died when we released the lock, so we need to make
1051                  * sure it's still around.
1052                  */
1053                 knotif = NULL;
1054                 mutex_lock(&filter->notify_lock);
1055                 list_for_each_entry(cur, &filter->notif->notifications, list) {
1056                         if (cur->id == unotif.id) {
1057                                 knotif = cur;
1058                                 break;
1059                         }
1060                 }
1061
1062                 if (knotif) {
1063                         knotif->state = SECCOMP_NOTIFY_INIT;
1064                         up(&filter->notif->request);
1065                 }
1066                 mutex_unlock(&filter->notify_lock);
1067         }
1068
1069         return ret;
1070 }
1071
1072 static long seccomp_notify_send(struct seccomp_filter *filter,
1073                                 void __user *buf)
1074 {
1075         struct seccomp_notif_resp resp = {};
1076         struct seccomp_knotif *knotif = NULL, *cur;
1077         long ret;
1078
1079         if (copy_from_user(&resp, buf, sizeof(resp)))
1080                 return -EFAULT;
1081
1082         if (resp.flags)
1083                 return -EINVAL;
1084
1085         ret = mutex_lock_interruptible(&filter->notify_lock);
1086         if (ret < 0)
1087                 return ret;
1088
1089         list_for_each_entry(cur, &filter->notif->notifications, list) {
1090                 if (cur->id == resp.id) {
1091                         knotif = cur;
1092                         break;
1093                 }
1094         }
1095
1096         if (!knotif) {
1097                 ret = -ENOENT;
1098                 goto out;
1099         }
1100
1101         /* Allow exactly one reply. */
1102         if (knotif->state != SECCOMP_NOTIFY_SENT) {
1103                 ret = -EINPROGRESS;
1104                 goto out;
1105         }
1106
1107         ret = 0;
1108         knotif->state = SECCOMP_NOTIFY_REPLIED;
1109         knotif->error = resp.error;
1110         knotif->val = resp.val;
1111         complete(&knotif->ready);
1112 out:
1113         mutex_unlock(&filter->notify_lock);
1114         return ret;
1115 }
1116
1117 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1118                                     void __user *buf)
1119 {
1120         struct seccomp_knotif *knotif = NULL;
1121         u64 id;
1122         long ret;
1123
1124         if (copy_from_user(&id, buf, sizeof(id)))
1125                 return -EFAULT;
1126
1127         ret = mutex_lock_interruptible(&filter->notify_lock);
1128         if (ret < 0)
1129                 return ret;
1130
1131         ret = -ENOENT;
1132         list_for_each_entry(knotif, &filter->notif->notifications, list) {
1133                 if (knotif->id == id) {
1134                         if (knotif->state == SECCOMP_NOTIFY_SENT)
1135                                 ret = 0;
1136                         goto out;
1137                 }
1138         }
1139
1140 out:
1141         mutex_unlock(&filter->notify_lock);
1142         return ret;
1143 }
1144
1145 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1146                                  unsigned long arg)
1147 {
1148         struct seccomp_filter *filter = file->private_data;
1149         void __user *buf = (void __user *)arg;
1150
1151         switch (cmd) {
1152         case SECCOMP_IOCTL_NOTIF_RECV:
1153                 return seccomp_notify_recv(filter, buf);
1154         case SECCOMP_IOCTL_NOTIF_SEND:
1155                 return seccomp_notify_send(filter, buf);
1156         case SECCOMP_IOCTL_NOTIF_ID_VALID:
1157                 return seccomp_notify_id_valid(filter, buf);
1158         default:
1159                 return -EINVAL;
1160         }
1161 }
1162
1163 static __poll_t seccomp_notify_poll(struct file *file,
1164                                     struct poll_table_struct *poll_tab)
1165 {
1166         struct seccomp_filter *filter = file->private_data;
1167         __poll_t ret = 0;
1168         struct seccomp_knotif *cur;
1169
1170         poll_wait(file, &filter->notif->wqh, poll_tab);
1171
1172         ret = mutex_lock_interruptible(&filter->notify_lock);
1173         if (ret < 0)
1174                 return EPOLLERR;
1175
1176         list_for_each_entry(cur, &filter->notif->notifications, list) {
1177                 if (cur->state == SECCOMP_NOTIFY_INIT)
1178                         ret |= EPOLLIN | EPOLLRDNORM;
1179                 if (cur->state == SECCOMP_NOTIFY_SENT)
1180                         ret |= EPOLLOUT | EPOLLWRNORM;
1181                 if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1182                         break;
1183         }
1184
1185         mutex_unlock(&filter->notify_lock);
1186
1187         return ret;
1188 }
1189
1190 static const struct file_operations seccomp_notify_ops = {
1191         .poll = seccomp_notify_poll,
1192         .release = seccomp_notify_release,
1193         .unlocked_ioctl = seccomp_notify_ioctl,
1194 };
1195
1196 static struct file *init_listener(struct seccomp_filter *filter)
1197 {
1198         struct file *ret = ERR_PTR(-EBUSY);
1199         struct seccomp_filter *cur;
1200
1201         for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1202                 if (cur->notif)
1203                         goto out;
1204         }
1205
1206         ret = ERR_PTR(-ENOMEM);
1207         filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1208         if (!filter->notif)
1209                 goto out;
1210
1211         sema_init(&filter->notif->request, 0);
1212         filter->notif->next_id = get_random_u64();
1213         INIT_LIST_HEAD(&filter->notif->notifications);
1214         init_waitqueue_head(&filter->notif->wqh);
1215
1216         ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1217                                  filter, O_RDWR);
1218         if (IS_ERR(ret))
1219                 goto out_notif;
1220
1221         /* The file has a reference to it now */
1222         __get_seccomp_filter(filter);
1223
1224 out_notif:
1225         if (IS_ERR(ret))
1226                 kfree(filter->notif);
1227 out:
1228         return ret;
1229 }
1230
1231 /**
1232  * seccomp_set_mode_filter: internal function for setting seccomp filter
1233  * @flags:  flags to change filter behavior
1234  * @filter: struct sock_fprog containing filter
1235  *
1236  * This function may be called repeatedly to install additional filters.
1237  * Every filter successfully installed will be evaluated (in reverse order)
1238  * for each system call the task makes.
1239  *
1240  * Once current->seccomp.mode is non-zero, it may not be changed.
1241  *
1242  * Returns 0 on success or -EINVAL on failure.
1243  */
1244 static long seccomp_set_mode_filter(unsigned int flags,
1245                                     const char __user *filter)
1246 {
1247         const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1248         struct seccomp_filter *prepared = NULL;
1249         long ret = -EINVAL;
1250         int listener = -1;
1251         struct file *listener_f = NULL;
1252
1253         /* Validate flags. */
1254         if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1255                 return -EINVAL;
1256
1257         /* Prepare the new filter before holding any locks. */
1258         prepared = seccomp_prepare_user_filter(filter);
1259         if (IS_ERR(prepared))
1260                 return PTR_ERR(prepared);
1261
1262         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1263                 listener = get_unused_fd_flags(O_CLOEXEC);
1264                 if (listener < 0) {
1265                         ret = listener;
1266                         goto out_free;
1267                 }
1268
1269                 listener_f = init_listener(prepared);
1270                 if (IS_ERR(listener_f)) {
1271                         put_unused_fd(listener);
1272                         ret = PTR_ERR(listener_f);
1273                         goto out_free;
1274                 }
1275         }
1276
1277         /*
1278          * Make sure we cannot change seccomp or nnp state via TSYNC
1279          * while another thread is in the middle of calling exec.
1280          */
1281         if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1282             mutex_lock_killable(&current->signal->cred_guard_mutex))
1283                 goto out_put_fd;
1284
1285         spin_lock_irq(&current->sighand->siglock);
1286
1287         if (!seccomp_may_assign_mode(seccomp_mode))
1288                 goto out;
1289
1290         ret = seccomp_attach_filter(flags, prepared);
1291         if (ret)
1292                 goto out;
1293         /* Do not free the successfully attached filter. */
1294         prepared = NULL;
1295
1296         seccomp_assign_mode(current, seccomp_mode, flags);
1297 out:
1298         spin_unlock_irq(&current->sighand->siglock);
1299         if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1300                 mutex_unlock(&current->signal->cred_guard_mutex);
1301 out_put_fd:
1302         if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1303                 if (ret < 0) {
1304                         fput(listener_f);
1305                         put_unused_fd(listener);
1306                 } else {
1307                         fd_install(listener, listener_f);
1308                         ret = listener;
1309                 }
1310         }
1311 out_free:
1312         seccomp_filter_free(prepared);
1313         return ret;
1314 }
1315 #else
1316 static inline long seccomp_set_mode_filter(unsigned int flags,
1317                                            const char __user *filter)
1318 {
1319         return -EINVAL;
1320 }
1321 #endif
1322
1323 static long seccomp_get_action_avail(const char __user *uaction)
1324 {
1325         u32 action;
1326
1327         if (copy_from_user(&action, uaction, sizeof(action)))
1328                 return -EFAULT;
1329
1330         switch (action) {
1331         case SECCOMP_RET_KILL_PROCESS:
1332         case SECCOMP_RET_KILL_THREAD:
1333         case SECCOMP_RET_TRAP:
1334         case SECCOMP_RET_ERRNO:
1335         case SECCOMP_RET_USER_NOTIF:
1336         case SECCOMP_RET_TRACE:
1337         case SECCOMP_RET_LOG:
1338         case SECCOMP_RET_ALLOW:
1339                 break;
1340         default:
1341                 return -EOPNOTSUPP;
1342         }
1343
1344         return 0;
1345 }
1346
1347 static long seccomp_get_notif_sizes(void __user *usizes)
1348 {
1349         struct seccomp_notif_sizes sizes = {
1350                 .seccomp_notif = sizeof(struct seccomp_notif),
1351                 .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1352                 .seccomp_data = sizeof(struct seccomp_data),
1353         };
1354
1355         if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1356                 return -EFAULT;
1357
1358         return 0;
1359 }
1360
1361 /* Common entry point for both prctl and syscall. */
1362 static long do_seccomp(unsigned int op, unsigned int flags,
1363                        void __user *uargs)
1364 {
1365         switch (op) {
1366         case SECCOMP_SET_MODE_STRICT:
1367                 if (flags != 0 || uargs != NULL)
1368                         return -EINVAL;
1369                 return seccomp_set_mode_strict();
1370         case SECCOMP_SET_MODE_FILTER:
1371                 return seccomp_set_mode_filter(flags, uargs);
1372         case SECCOMP_GET_ACTION_AVAIL:
1373                 if (flags != 0)
1374                         return -EINVAL;
1375
1376                 return seccomp_get_action_avail(uargs);
1377         case SECCOMP_GET_NOTIF_SIZES:
1378                 if (flags != 0)
1379                         return -EINVAL;
1380
1381                 return seccomp_get_notif_sizes(uargs);
1382         default:
1383                 return -EINVAL;
1384         }
1385 }
1386
1387 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
1388                          void __user *, uargs)
1389 {
1390         return do_seccomp(op, flags, uargs);
1391 }
1392
1393 /**
1394  * prctl_set_seccomp: configures current->seccomp.mode
1395  * @seccomp_mode: requested mode to use
1396  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
1397  *
1398  * Returns 0 on success or -EINVAL on failure.
1399  */
1400 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
1401 {
1402         unsigned int op;
1403         void __user *uargs;
1404
1405         switch (seccomp_mode) {
1406         case SECCOMP_MODE_STRICT:
1407                 op = SECCOMP_SET_MODE_STRICT;
1408                 /*
1409                  * Setting strict mode through prctl always ignored filter,
1410                  * so make sure it is always NULL here to pass the internal
1411                  * check in do_seccomp().
1412                  */
1413                 uargs = NULL;
1414                 break;
1415         case SECCOMP_MODE_FILTER:
1416                 op = SECCOMP_SET_MODE_FILTER;
1417                 uargs = filter;
1418                 break;
1419         default:
1420                 return -EINVAL;
1421         }
1422
1423         /* prctl interface doesn't have flags, so they are always zero. */
1424         return do_seccomp(op, 0, uargs);
1425 }
1426
1427 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
1428 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
1429                                              unsigned long filter_off)
1430 {
1431         struct seccomp_filter *orig, *filter;
1432         unsigned long count;
1433
1434         /*
1435          * Note: this is only correct because the caller should be the (ptrace)
1436          * tracer of the task, otherwise lock_task_sighand is needed.
1437          */
1438         spin_lock_irq(&task->sighand->siglock);
1439
1440         if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
1441                 spin_unlock_irq(&task->sighand->siglock);
1442                 return ERR_PTR(-EINVAL);
1443         }
1444
1445         orig = task->seccomp.filter;
1446         __get_seccomp_filter(orig);
1447         spin_unlock_irq(&task->sighand->siglock);
1448
1449         count = 0;
1450         for (filter = orig; filter; filter = filter->prev)
1451                 count++;
1452
1453         if (filter_off >= count) {
1454                 filter = ERR_PTR(-ENOENT);
1455                 goto out;
1456         }
1457
1458         count -= filter_off;
1459         for (filter = orig; filter && count > 1; filter = filter->prev)
1460                 count--;
1461
1462         if (WARN_ON(count != 1 || !filter)) {
1463                 filter = ERR_PTR(-ENOENT);
1464                 goto out;
1465         }
1466
1467         __get_seccomp_filter(filter);
1468
1469 out:
1470         __put_seccomp_filter(orig);
1471         return filter;
1472 }
1473
1474 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
1475                         void __user *data)
1476 {
1477         struct seccomp_filter *filter;
1478         struct sock_fprog_kern *fprog;
1479         long ret;
1480
1481         if (!capable(CAP_SYS_ADMIN) ||
1482             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1483                 return -EACCES;
1484         }
1485
1486         filter = get_nth_filter(task, filter_off);
1487         if (IS_ERR(filter))
1488                 return PTR_ERR(filter);
1489
1490         fprog = filter->prog->orig_prog;
1491         if (!fprog) {
1492                 /* This must be a new non-cBPF filter, since we save
1493                  * every cBPF filter's orig_prog above when
1494                  * CONFIG_CHECKPOINT_RESTORE is enabled.
1495                  */
1496                 ret = -EMEDIUMTYPE;
1497                 goto out;
1498         }
1499
1500         ret = fprog->len;
1501         if (!data)
1502                 goto out;
1503
1504         if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
1505                 ret = -EFAULT;
1506
1507 out:
1508         __put_seccomp_filter(filter);
1509         return ret;
1510 }
1511
1512 long seccomp_get_metadata(struct task_struct *task,
1513                           unsigned long size, void __user *data)
1514 {
1515         long ret;
1516         struct seccomp_filter *filter;
1517         struct seccomp_metadata kmd = {};
1518
1519         if (!capable(CAP_SYS_ADMIN) ||
1520             current->seccomp.mode != SECCOMP_MODE_DISABLED) {
1521                 return -EACCES;
1522         }
1523
1524         size = min_t(unsigned long, size, sizeof(kmd));
1525
1526         if (size < sizeof(kmd.filter_off))
1527                 return -EINVAL;
1528
1529         if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
1530                 return -EFAULT;
1531
1532         filter = get_nth_filter(task, kmd.filter_off);
1533         if (IS_ERR(filter))
1534                 return PTR_ERR(filter);
1535
1536         if (filter->log)
1537                 kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
1538
1539         ret = size;
1540         if (copy_to_user(data, &kmd, size))
1541                 ret = -EFAULT;
1542
1543         __put_seccomp_filter(filter);
1544         return ret;
1545 }
1546 #endif
1547
1548 #ifdef CONFIG_SYSCTL
1549
1550 /* Human readable action names for friendly sysctl interaction */
1551 #define SECCOMP_RET_KILL_PROCESS_NAME   "kill_process"
1552 #define SECCOMP_RET_KILL_THREAD_NAME    "kill_thread"
1553 #define SECCOMP_RET_TRAP_NAME           "trap"
1554 #define SECCOMP_RET_ERRNO_NAME          "errno"
1555 #define SECCOMP_RET_USER_NOTIF_NAME     "user_notif"
1556 #define SECCOMP_RET_TRACE_NAME          "trace"
1557 #define SECCOMP_RET_LOG_NAME            "log"
1558 #define SECCOMP_RET_ALLOW_NAME          "allow"
1559
1560 static const char seccomp_actions_avail[] =
1561                                 SECCOMP_RET_KILL_PROCESS_NAME   " "
1562                                 SECCOMP_RET_KILL_THREAD_NAME    " "
1563                                 SECCOMP_RET_TRAP_NAME           " "
1564                                 SECCOMP_RET_ERRNO_NAME          " "
1565                                 SECCOMP_RET_USER_NOTIF_NAME     " "
1566                                 SECCOMP_RET_TRACE_NAME          " "
1567                                 SECCOMP_RET_LOG_NAME            " "
1568                                 SECCOMP_RET_ALLOW_NAME;
1569
1570 struct seccomp_log_name {
1571         u32             log;
1572         const char      *name;
1573 };
1574
1575 static const struct seccomp_log_name seccomp_log_names[] = {
1576         { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
1577         { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
1578         { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
1579         { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
1580         { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
1581         { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
1582         { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
1583         { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
1584         { }
1585 };
1586
1587 static bool seccomp_names_from_actions_logged(char *names, size_t size,
1588                                               u32 actions_logged,
1589                                               const char *sep)
1590 {
1591         const struct seccomp_log_name *cur;
1592         bool append_sep = false;
1593
1594         for (cur = seccomp_log_names; cur->name && size; cur++) {
1595                 ssize_t ret;
1596
1597                 if (!(actions_logged & cur->log))
1598                         continue;
1599
1600                 if (append_sep) {
1601                         ret = strscpy(names, sep, size);
1602                         if (ret < 0)
1603                                 return false;
1604
1605                         names += ret;
1606                         size -= ret;
1607                 } else
1608                         append_sep = true;
1609
1610                 ret = strscpy(names, cur->name, size);
1611                 if (ret < 0)
1612                         return false;
1613
1614                 names += ret;
1615                 size -= ret;
1616         }
1617
1618         return true;
1619 }
1620
1621 static bool seccomp_action_logged_from_name(u32 *action_logged,
1622                                             const char *name)
1623 {
1624         const struct seccomp_log_name *cur;
1625
1626         for (cur = seccomp_log_names; cur->name; cur++) {
1627                 if (!strcmp(cur->name, name)) {
1628                         *action_logged = cur->log;
1629                         return true;
1630                 }
1631         }
1632
1633         return false;
1634 }
1635
1636 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
1637 {
1638         char *name;
1639
1640         *actions_logged = 0;
1641         while ((name = strsep(&names, " ")) && *name) {
1642                 u32 action_logged = 0;
1643
1644                 if (!seccomp_action_logged_from_name(&action_logged, name))
1645                         return false;
1646
1647                 *actions_logged |= action_logged;
1648         }
1649
1650         return true;
1651 }
1652
1653 static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1654                                size_t *lenp, loff_t *ppos)
1655 {
1656         char names[sizeof(seccomp_actions_avail)];
1657         struct ctl_table table;
1658
1659         memset(names, 0, sizeof(names));
1660
1661         if (!seccomp_names_from_actions_logged(names, sizeof(names),
1662                                                seccomp_actions_logged, " "))
1663                 return -EINVAL;
1664
1665         table = *ro_table;
1666         table.data = names;
1667         table.maxlen = sizeof(names);
1668         return proc_dostring(&table, 0, buffer, lenp, ppos);
1669 }
1670
1671 static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer,
1672                                 size_t *lenp, loff_t *ppos, u32 *actions_logged)
1673 {
1674         char names[sizeof(seccomp_actions_avail)];
1675         struct ctl_table table;
1676         int ret;
1677
1678         if (!capable(CAP_SYS_ADMIN))
1679                 return -EPERM;
1680
1681         memset(names, 0, sizeof(names));
1682
1683         table = *ro_table;
1684         table.data = names;
1685         table.maxlen = sizeof(names);
1686         ret = proc_dostring(&table, 1, buffer, lenp, ppos);
1687         if (ret)
1688                 return ret;
1689
1690         if (!seccomp_actions_logged_from_names(actions_logged, table.data))
1691                 return -EINVAL;
1692
1693         if (*actions_logged & SECCOMP_LOG_ALLOW)
1694                 return -EINVAL;
1695
1696         seccomp_actions_logged = *actions_logged;
1697         return 0;
1698 }
1699
1700 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
1701                                  int ret)
1702 {
1703         char names[sizeof(seccomp_actions_avail)];
1704         char old_names[sizeof(seccomp_actions_avail)];
1705         const char *new = names;
1706         const char *old = old_names;
1707
1708         if (!audit_enabled)
1709                 return;
1710
1711         memset(names, 0, sizeof(names));
1712         memset(old_names, 0, sizeof(old_names));
1713
1714         if (ret)
1715                 new = "?";
1716         else if (!actions_logged)
1717                 new = "(none)";
1718         else if (!seccomp_names_from_actions_logged(names, sizeof(names),
1719                                                     actions_logged, ","))
1720                 new = "?";
1721
1722         if (!old_actions_logged)
1723                 old = "(none)";
1724         else if (!seccomp_names_from_actions_logged(old_names,
1725                                                     sizeof(old_names),
1726                                                     old_actions_logged, ","))
1727                 old = "?";
1728
1729         return audit_seccomp_actions_logged(new, old, !ret);
1730 }
1731
1732 static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
1733                                           void __user *buffer, size_t *lenp,
1734                                           loff_t *ppos)
1735 {
1736         int ret;
1737
1738         if (write) {
1739                 u32 actions_logged = 0;
1740                 u32 old_actions_logged = seccomp_actions_logged;
1741
1742                 ret = write_actions_logged(ro_table, buffer, lenp, ppos,
1743                                            &actions_logged);
1744                 audit_actions_logged(actions_logged, old_actions_logged, ret);
1745         } else
1746                 ret = read_actions_logged(ro_table, buffer, lenp, ppos);
1747
1748         return ret;
1749 }
1750
1751 static struct ctl_path seccomp_sysctl_path[] = {
1752         { .procname = "kernel", },
1753         { .procname = "seccomp", },
1754         { }
1755 };
1756
1757 static struct ctl_table seccomp_sysctl_table[] = {
1758         {
1759                 .procname       = "actions_avail",
1760                 .data           = (void *) &seccomp_actions_avail,
1761                 .maxlen         = sizeof(seccomp_actions_avail),
1762                 .mode           = 0444,
1763                 .proc_handler   = proc_dostring,
1764         },
1765         {
1766                 .procname       = "actions_logged",
1767                 .mode           = 0644,
1768                 .proc_handler   = seccomp_actions_logged_handler,
1769         },
1770         { }
1771 };
1772
1773 static int __init seccomp_sysctl_init(void)
1774 {
1775         struct ctl_table_header *hdr;
1776
1777         hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
1778         if (!hdr)
1779                 pr_warn("seccomp: sysctl registration failed\n");
1780         else
1781                 kmemleak_not_leak(hdr);
1782
1783         return 0;
1784 }
1785
1786 device_initcall(seccomp_sysctl_init)
1787
1788 #endif /* CONFIG_SYSCTL */