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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/kernel/seccomp.c | |
4 | * | |
5 | * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com> | |
6 | * | |
e2cfabdf WD |
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. | |
1da177e4 | 15 | */ |
e68f9d49 | 16 | #define pr_fmt(fmt) "seccomp: " fmt |
1da177e4 | 17 | |
0b5fa229 | 18 | #include <linux/refcount.h> |
85e7bac3 | 19 | #include <linux/audit.h> |
5b101740 | 20 | #include <linux/compat.h> |
b25e6716 | 21 | #include <linux/coredump.h> |
8e5f1ad1 | 22 | #include <linux/kmemleak.h> |
5c307089 KC |
23 | #include <linux/nospec.h> |
24 | #include <linux/prctl.h> | |
e2cfabdf | 25 | #include <linux/sched.h> |
68db0cf1 | 26 | #include <linux/sched/task_stack.h> |
e2cfabdf | 27 | #include <linux/seccomp.h> |
c8bee430 | 28 | #include <linux/slab.h> |
48dc92b9 | 29 | #include <linux/syscalls.h> |
8e5f1ad1 | 30 | #include <linux/sysctl.h> |
1da177e4 | 31 | |
495ac306 KC |
32 | /* Not exposed in headers: strictly internal use only. */ |
33 | #define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1) | |
34 | ||
a4412fc9 | 35 | #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER |
e2cfabdf | 36 | #include <asm/syscall.h> |
a4412fc9 | 37 | #endif |
e2cfabdf WD |
38 | |
39 | #ifdef CONFIG_SECCOMP_FILTER | |
6a21cc50 | 40 | #include <linux/file.h> |
e2cfabdf | 41 | #include <linux/filter.h> |
c2e1f2e3 | 42 | #include <linux/pid.h> |
fb0fadf9 | 43 | #include <linux/ptrace.h> |
fb14528e | 44 | #include <linux/capability.h> |
e2cfabdf | 45 | #include <linux/uaccess.h> |
6a21cc50 | 46 | #include <linux/anon_inodes.h> |
9f87dcf1 | 47 | #include <linux/lockdep.h> |
6a21cc50 | 48 | |
47e33c05 KC |
49 | /* |
50 | * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the | |
51 | * wrong direction flag in the ioctl number. This is the broken one, | |
52 | * which the kernel needs to keep supporting until all userspaces stop | |
53 | * using the wrong command number. | |
54 | */ | |
55 | #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64) | |
56 | ||
6a21cc50 TA |
57 | enum notify_state { |
58 | SECCOMP_NOTIFY_INIT, | |
59 | SECCOMP_NOTIFY_SENT, | |
60 | SECCOMP_NOTIFY_REPLIED, | |
61 | }; | |
62 | ||
63 | struct seccomp_knotif { | |
64 | /* The struct pid of the task whose filter triggered the notification */ | |
65 | struct task_struct *task; | |
66 | ||
67 | /* The "cookie" for this request; this is unique for this filter. */ | |
68 | u64 id; | |
69 | ||
70 | /* | |
71 | * The seccomp data. This pointer is valid the entire time this | |
72 | * notification is active, since it comes from __seccomp_filter which | |
73 | * eclipses the entire lifecycle here. | |
74 | */ | |
75 | const struct seccomp_data *data; | |
76 | ||
77 | /* | |
78 | * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a | |
79 | * struct seccomp_knotif is created and starts out in INIT. Once the | |
80 | * handler reads the notification off of an FD, it transitions to SENT. | |
81 | * If a signal is received the state transitions back to INIT and | |
82 | * another message is sent. When the userspace handler replies, state | |
83 | * transitions to REPLIED. | |
84 | */ | |
85 | enum notify_state state; | |
86 | ||
87 | /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */ | |
88 | int error; | |
89 | long val; | |
fb3c5386 | 90 | u32 flags; |
6a21cc50 | 91 | |
7cf97b12 SD |
92 | /* |
93 | * Signals when this has changed states, such as the listener | |
94 | * dying, a new seccomp addfd message, or changing to REPLIED | |
95 | */ | |
6a21cc50 TA |
96 | struct completion ready; |
97 | ||
98 | struct list_head list; | |
7cf97b12 SD |
99 | |
100 | /* outstanding addfd requests */ | |
101 | struct list_head addfd; | |
102 | }; | |
103 | ||
104 | /** | |
105 | * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages | |
106 | * | |
107 | * @file: A reference to the file to install in the other task | |
108 | * @fd: The fd number to install it at. If the fd number is -1, it means the | |
109 | * installing process should allocate the fd as normal. | |
110 | * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC | |
111 | * is allowed. | |
0ae71c77 | 112 | * @ioctl_flags: The flags used for the seccomp_addfd ioctl. |
7cf97b12 SD |
113 | * @ret: The return value of the installing process. It is set to the fd num |
114 | * upon success (>= 0). | |
115 | * @completion: Indicates that the installing process has completed fd | |
116 | * installation, or gone away (either due to successful | |
117 | * reply, or signal) | |
118 | * | |
119 | */ | |
120 | struct seccomp_kaddfd { | |
121 | struct file *file; | |
122 | int fd; | |
123 | unsigned int flags; | |
0ae71c77 | 124 | __u32 ioctl_flags; |
7cf97b12 | 125 | |
42eb0d54 CH |
126 | union { |
127 | bool setfd; | |
128 | /* To only be set on reply */ | |
129 | int ret; | |
130 | }; | |
7cf97b12 SD |
131 | struct completion completion; |
132 | struct list_head list; | |
6a21cc50 TA |
133 | }; |
134 | ||
135 | /** | |
136 | * struct notification - container for seccomp userspace notifications. Since | |
137 | * most seccomp filters will not have notification listeners attached and this | |
138 | * structure is fairly large, we store the notification-specific stuff in a | |
139 | * separate structure. | |
140 | * | |
141 | * @request: A semaphore that users of this notification can wait on for | |
142 | * changes. Actual reads and writes are still controlled with | |
143 | * filter->notify_lock. | |
144 | * @next_id: The id of the next request. | |
145 | * @notifications: A list of struct seccomp_knotif elements. | |
6a21cc50 TA |
146 | */ |
147 | struct notification { | |
148 | struct semaphore request; | |
149 | u64 next_id; | |
150 | struct list_head notifications; | |
6a21cc50 | 151 | }; |
e2cfabdf | 152 | |
f9d480b6 YZ |
153 | #ifdef SECCOMP_ARCH_NATIVE |
154 | /** | |
155 | * struct action_cache - per-filter cache of seccomp actions per | |
156 | * arch/syscall pair | |
157 | * | |
158 | * @allow_native: A bitmap where each bit represents whether the | |
159 | * filter will always allow the syscall, for the | |
160 | * native architecture. | |
161 | * @allow_compat: A bitmap where each bit represents whether the | |
162 | * filter will always allow the syscall, for the | |
163 | * compat architecture. | |
164 | */ | |
165 | struct action_cache { | |
166 | DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR); | |
167 | #ifdef SECCOMP_ARCH_COMPAT | |
168 | DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR); | |
169 | #endif | |
170 | }; | |
171 | #else | |
172 | struct action_cache { }; | |
173 | ||
174 | static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter, | |
175 | const struct seccomp_data *sd) | |
176 | { | |
177 | return false; | |
178 | } | |
8e01b51a YZ |
179 | |
180 | static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter) | |
181 | { | |
182 | } | |
f9d480b6 YZ |
183 | #endif /* SECCOMP_ARCH_NATIVE */ |
184 | ||
e2cfabdf WD |
185 | /** |
186 | * struct seccomp_filter - container for seccomp BPF programs | |
187 | * | |
b707ddee CB |
188 | * @refs: Reference count to manage the object lifetime. |
189 | * A filter's reference count is incremented for each directly | |
190 | * attached task, once for the dependent filter, and if | |
191 | * requested for the user notifier. When @refs reaches zero, | |
192 | * the filter can be freed. | |
99cdb8b9 CB |
193 | * @users: A filter's @users count is incremented for each directly |
194 | * attached task (filter installation, fork(), thread_sync), | |
195 | * and once for the dependent filter (tracked in filter->prev). | |
196 | * When it reaches zero it indicates that no direct or indirect | |
197 | * users of that filter exist. No new tasks can get associated with | |
198 | * this filter after reaching 0. The @users count is always smaller | |
199 | * or equal to @refs. Hence, reaching 0 for @users does not mean | |
200 | * the filter can be freed. | |
8e01b51a | 201 | * @cache: cache of arch/syscall mappings to actions |
e66a3997 | 202 | * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged |
e2cfabdf | 203 | * @prev: points to a previously installed, or inherited, filter |
285fdfc5 | 204 | * @prog: the BPF program to evaluate |
6a21cc50 TA |
205 | * @notif: the struct that holds all notification related information |
206 | * @notify_lock: A lock for all notification-related accesses. | |
76194c4e | 207 | * @wqh: A wait queue for poll if a notifier is in use. |
e2cfabdf WD |
208 | * |
209 | * seccomp_filter objects are organized in a tree linked via the @prev | |
210 | * pointer. For any task, it appears to be a singly-linked list starting | |
211 | * with current->seccomp.filter, the most recently attached or inherited filter. | |
212 | * However, multiple filters may share a @prev node, by way of fork(), which | |
213 | * results in a unidirectional tree existing in memory. This is similar to | |
214 | * how namespaces work. | |
215 | * | |
216 | * seccomp_filter objects should never be modified after being attached | |
b707ddee | 217 | * to a task_struct (other than @refs). |
e2cfabdf WD |
218 | */ |
219 | struct seccomp_filter { | |
b707ddee | 220 | refcount_t refs; |
99cdb8b9 | 221 | refcount_t users; |
e66a3997 | 222 | bool log; |
8e01b51a | 223 | struct action_cache cache; |
e2cfabdf | 224 | struct seccomp_filter *prev; |
7ae457c1 | 225 | struct bpf_prog *prog; |
6a21cc50 TA |
226 | struct notification *notif; |
227 | struct mutex notify_lock; | |
76194c4e | 228 | wait_queue_head_t wqh; |
e2cfabdf WD |
229 | }; |
230 | ||
231 | /* Limit any path through the tree to 256KB worth of instructions. */ | |
232 | #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) | |
233 | ||
bd4cf0ed | 234 | /* |
e2cfabdf WD |
235 | * Endianness is explicitly ignored and left for BPF program authors to manage |
236 | * as per the specific architecture. | |
237 | */ | |
bd4cf0ed | 238 | static void populate_seccomp_data(struct seccomp_data *sd) |
e2cfabdf | 239 | { |
2d9ca267 DE |
240 | /* |
241 | * Instead of using current_pt_reg(), we're already doing the work | |
242 | * to safely fetch "current", so just use "task" everywhere below. | |
243 | */ | |
bd4cf0ed AS |
244 | struct task_struct *task = current; |
245 | struct pt_regs *regs = task_pt_regs(task); | |
2eac7648 | 246 | unsigned long args[6]; |
e2cfabdf | 247 | |
bd4cf0ed | 248 | sd->nr = syscall_get_nr(task, regs); |
16add411 | 249 | sd->arch = syscall_get_arch(task); |
b35f549d | 250 | syscall_get_arguments(task, regs, args); |
2eac7648 DB |
251 | sd->args[0] = args[0]; |
252 | sd->args[1] = args[1]; | |
253 | sd->args[2] = args[2]; | |
254 | sd->args[3] = args[3]; | |
255 | sd->args[4] = args[4]; | |
256 | sd->args[5] = args[5]; | |
bd4cf0ed | 257 | sd->instruction_pointer = KSTK_EIP(task); |
e2cfabdf WD |
258 | } |
259 | ||
260 | /** | |
261 | * seccomp_check_filter - verify seccomp filter code | |
262 | * @filter: filter to verify | |
263 | * @flen: length of filter | |
264 | * | |
4df95ff4 | 265 | * Takes a previously checked filter (by bpf_check_classic) and |
e2cfabdf WD |
266 | * redirects all filter code that loads struct sk_buff data |
267 | * and related data through seccomp_bpf_load. It also | |
268 | * enforces length and alignment checking of those loads. | |
269 | * | |
270 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
271 | */ | |
272 | static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) | |
273 | { | |
274 | int pc; | |
275 | for (pc = 0; pc < flen; pc++) { | |
276 | struct sock_filter *ftest = &filter[pc]; | |
277 | u16 code = ftest->code; | |
278 | u32 k = ftest->k; | |
279 | ||
280 | switch (code) { | |
34805931 | 281 | case BPF_LD | BPF_W | BPF_ABS: |
bd4cf0ed | 282 | ftest->code = BPF_LDX | BPF_W | BPF_ABS; |
e2cfabdf WD |
283 | /* 32-bit aligned and not out of bounds. */ |
284 | if (k >= sizeof(struct seccomp_data) || k & 3) | |
285 | return -EINVAL; | |
286 | continue; | |
34805931 | 287 | case BPF_LD | BPF_W | BPF_LEN: |
bd4cf0ed | 288 | ftest->code = BPF_LD | BPF_IMM; |
e2cfabdf WD |
289 | ftest->k = sizeof(struct seccomp_data); |
290 | continue; | |
34805931 | 291 | case BPF_LDX | BPF_W | BPF_LEN: |
bd4cf0ed | 292 | ftest->code = BPF_LDX | BPF_IMM; |
e2cfabdf WD |
293 | ftest->k = sizeof(struct seccomp_data); |
294 | continue; | |
295 | /* Explicitly include allowed calls. */ | |
34805931 DB |
296 | case BPF_RET | BPF_K: |
297 | case BPF_RET | BPF_A: | |
298 | case BPF_ALU | BPF_ADD | BPF_K: | |
299 | case BPF_ALU | BPF_ADD | BPF_X: | |
300 | case BPF_ALU | BPF_SUB | BPF_K: | |
301 | case BPF_ALU | BPF_SUB | BPF_X: | |
302 | case BPF_ALU | BPF_MUL | BPF_K: | |
303 | case BPF_ALU | BPF_MUL | BPF_X: | |
304 | case BPF_ALU | BPF_DIV | BPF_K: | |
305 | case BPF_ALU | BPF_DIV | BPF_X: | |
306 | case BPF_ALU | BPF_AND | BPF_K: | |
307 | case BPF_ALU | BPF_AND | BPF_X: | |
308 | case BPF_ALU | BPF_OR | BPF_K: | |
309 | case BPF_ALU | BPF_OR | BPF_X: | |
310 | case BPF_ALU | BPF_XOR | BPF_K: | |
311 | case BPF_ALU | BPF_XOR | BPF_X: | |
312 | case BPF_ALU | BPF_LSH | BPF_K: | |
313 | case BPF_ALU | BPF_LSH | BPF_X: | |
314 | case BPF_ALU | BPF_RSH | BPF_K: | |
315 | case BPF_ALU | BPF_RSH | BPF_X: | |
316 | case BPF_ALU | BPF_NEG: | |
317 | case BPF_LD | BPF_IMM: | |
318 | case BPF_LDX | BPF_IMM: | |
319 | case BPF_MISC | BPF_TAX: | |
320 | case BPF_MISC | BPF_TXA: | |
321 | case BPF_LD | BPF_MEM: | |
322 | case BPF_LDX | BPF_MEM: | |
323 | case BPF_ST: | |
324 | case BPF_STX: | |
325 | case BPF_JMP | BPF_JA: | |
326 | case BPF_JMP | BPF_JEQ | BPF_K: | |
327 | case BPF_JMP | BPF_JEQ | BPF_X: | |
328 | case BPF_JMP | BPF_JGE | BPF_K: | |
329 | case BPF_JMP | BPF_JGE | BPF_X: | |
330 | case BPF_JMP | BPF_JGT | BPF_K: | |
331 | case BPF_JMP | BPF_JGT | BPF_X: | |
332 | case BPF_JMP | BPF_JSET | BPF_K: | |
333 | case BPF_JMP | BPF_JSET | BPF_X: | |
e2cfabdf WD |
334 | continue; |
335 | default: | |
336 | return -EINVAL; | |
337 | } | |
338 | } | |
339 | return 0; | |
340 | } | |
341 | ||
f9d480b6 YZ |
342 | #ifdef SECCOMP_ARCH_NATIVE |
343 | static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap, | |
344 | size_t bitmap_size, | |
345 | int syscall_nr) | |
346 | { | |
347 | if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size)) | |
348 | return false; | |
349 | syscall_nr = array_index_nospec(syscall_nr, bitmap_size); | |
350 | ||
351 | return test_bit(syscall_nr, bitmap); | |
352 | } | |
353 | ||
354 | /** | |
355 | * seccomp_cache_check_allow - lookup seccomp cache | |
356 | * @sfilter: The seccomp filter | |
357 | * @sd: The seccomp data to lookup the cache with | |
358 | * | |
359 | * Returns true if the seccomp_data is cached and allowed. | |
360 | */ | |
361 | static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter, | |
362 | const struct seccomp_data *sd) | |
363 | { | |
364 | int syscall_nr = sd->nr; | |
365 | const struct action_cache *cache = &sfilter->cache; | |
366 | ||
367 | #ifndef SECCOMP_ARCH_COMPAT | |
368 | /* A native-only architecture doesn't need to check sd->arch. */ | |
369 | return seccomp_cache_check_allow_bitmap(cache->allow_native, | |
370 | SECCOMP_ARCH_NATIVE_NR, | |
371 | syscall_nr); | |
372 | #else | |
373 | if (likely(sd->arch == SECCOMP_ARCH_NATIVE)) | |
374 | return seccomp_cache_check_allow_bitmap(cache->allow_native, | |
375 | SECCOMP_ARCH_NATIVE_NR, | |
376 | syscall_nr); | |
377 | if (likely(sd->arch == SECCOMP_ARCH_COMPAT)) | |
378 | return seccomp_cache_check_allow_bitmap(cache->allow_compat, | |
379 | SECCOMP_ARCH_COMPAT_NR, | |
380 | syscall_nr); | |
381 | #endif /* SECCOMP_ARCH_COMPAT */ | |
382 | ||
383 | WARN_ON_ONCE(true); | |
384 | return false; | |
385 | } | |
386 | #endif /* SECCOMP_ARCH_NATIVE */ | |
387 | ||
e2cfabdf | 388 | /** |
285fdfc5 MS |
389 | * seccomp_run_filters - evaluates all seccomp filters against @sd |
390 | * @sd: optional seccomp data to be passed to filters | |
deb4de8b KC |
391 | * @match: stores struct seccomp_filter that resulted in the return value, |
392 | * unless filter returned SECCOMP_RET_ALLOW, in which case it will | |
393 | * be unchanged. | |
e2cfabdf WD |
394 | * |
395 | * Returns valid seccomp BPF response codes. | |
396 | */ | |
0466bdb9 | 397 | #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL))) |
deb4de8b KC |
398 | static u32 seccomp_run_filters(const struct seccomp_data *sd, |
399 | struct seccomp_filter **match) | |
e2cfabdf | 400 | { |
acf3b2c7 | 401 | u32 ret = SECCOMP_RET_ALLOW; |
8225d385 PK |
402 | /* Make sure cross-thread synced filter points somewhere sane. */ |
403 | struct seccomp_filter *f = | |
506458ef | 404 | READ_ONCE(current->seccomp.filter); |
acf3b2c7 WD |
405 | |
406 | /* Ensure unexpected behavior doesn't result in failing open. */ | |
0d42d73a | 407 | if (WARN_ON(f == NULL)) |
4d3b0b05 | 408 | return SECCOMP_RET_KILL_PROCESS; |
acf3b2c7 | 409 | |
f9d480b6 YZ |
410 | if (seccomp_cache_check_allow(f, sd)) |
411 | return SECCOMP_RET_ALLOW; | |
412 | ||
e2cfabdf WD |
413 | /* |
414 | * All filters in the list are evaluated and the lowest BPF return | |
acf3b2c7 | 415 | * value always takes priority (ignoring the DATA). |
e2cfabdf | 416 | */ |
3ba2530c | 417 | for (; f; f = f->prev) { |
3d9f773c | 418 | u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd); |
8f577cad | 419 | |
0466bdb9 | 420 | if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) { |
acf3b2c7 | 421 | ret = cur_ret; |
deb4de8b KC |
422 | *match = f; |
423 | } | |
e2cfabdf WD |
424 | } |
425 | return ret; | |
426 | } | |
1f41b450 | 427 | #endif /* CONFIG_SECCOMP_FILTER */ |
e2cfabdf | 428 | |
1f41b450 KC |
429 | static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) |
430 | { | |
69f6a34b | 431 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 432 | |
1f41b450 KC |
433 | if (current->seccomp.mode && current->seccomp.mode != seccomp_mode) |
434 | return false; | |
435 | ||
436 | return true; | |
437 | } | |
438 | ||
8bf37d8c | 439 | void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { } |
5c307089 | 440 | |
3ba2530c | 441 | static inline void seccomp_assign_mode(struct task_struct *task, |
00a02d0c KC |
442 | unsigned long seccomp_mode, |
443 | unsigned long flags) | |
1f41b450 | 444 | { |
69f6a34b | 445 | assert_spin_locked(&task->sighand->siglock); |
dbd95212 | 446 | |
3ba2530c KC |
447 | task->seccomp.mode = seccomp_mode; |
448 | /* | |
23d67a54 | 449 | * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and |
3ba2530c KC |
450 | * filter) is set. |
451 | */ | |
452 | smp_mb__before_atomic(); | |
00a02d0c KC |
453 | /* Assume default seccomp processes want spec flaw mitigation. */ |
454 | if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0) | |
8bf37d8c | 455 | arch_seccomp_spec_mitigate(task); |
23d67a54 | 456 | set_task_syscall_work(task, SECCOMP); |
1f41b450 KC |
457 | } |
458 | ||
459 | #ifdef CONFIG_SECCOMP_FILTER | |
c2e1f2e3 KC |
460 | /* Returns 1 if the parent is an ancestor of the child. */ |
461 | static int is_ancestor(struct seccomp_filter *parent, | |
462 | struct seccomp_filter *child) | |
463 | { | |
464 | /* NULL is the root ancestor. */ | |
465 | if (parent == NULL) | |
466 | return 1; | |
467 | for (; child; child = child->prev) | |
468 | if (child == parent) | |
469 | return 1; | |
470 | return 0; | |
471 | } | |
472 | ||
473 | /** | |
474 | * seccomp_can_sync_threads: checks if all threads can be synchronized | |
475 | * | |
476 | * Expects sighand and cred_guard_mutex locks to be held. | |
477 | * | |
478 | * Returns 0 on success, -ve on error, or the pid of a thread which was | |
6beff00b | 479 | * either not in the correct seccomp mode or did not have an ancestral |
c2e1f2e3 KC |
480 | * seccomp filter. |
481 | */ | |
482 | static inline pid_t seccomp_can_sync_threads(void) | |
483 | { | |
484 | struct task_struct *thread, *caller; | |
485 | ||
486 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 487 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
488 | |
489 | /* Validate all threads being eligible for synchronization. */ | |
490 | caller = current; | |
491 | for_each_thread(caller, thread) { | |
492 | pid_t failed; | |
493 | ||
494 | /* Skip current, since it is initiating the sync. */ | |
495 | if (thread == caller) | |
496 | continue; | |
497 | ||
498 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || | |
499 | (thread->seccomp.mode == SECCOMP_MODE_FILTER && | |
500 | is_ancestor(thread->seccomp.filter, | |
501 | caller->seccomp.filter))) | |
502 | continue; | |
503 | ||
504 | /* Return the first thread that cannot be synchronized. */ | |
505 | failed = task_pid_vnr(thread); | |
506 | /* If the pid cannot be resolved, then return -ESRCH */ | |
0d42d73a | 507 | if (WARN_ON(failed == 0)) |
c2e1f2e3 KC |
508 | failed = -ESRCH; |
509 | return failed; | |
510 | } | |
511 | ||
512 | return 0; | |
513 | } | |
514 | ||
3a15fb6e CB |
515 | static inline void seccomp_filter_free(struct seccomp_filter *filter) |
516 | { | |
517 | if (filter) { | |
518 | bpf_prog_destroy(filter->prog); | |
519 | kfree(filter); | |
520 | } | |
521 | } | |
522 | ||
99cdb8b9 CB |
523 | static void __seccomp_filter_orphan(struct seccomp_filter *orig) |
524 | { | |
525 | while (orig && refcount_dec_and_test(&orig->users)) { | |
526 | if (waitqueue_active(&orig->wqh)) | |
527 | wake_up_poll(&orig->wqh, EPOLLHUP); | |
528 | orig = orig->prev; | |
529 | } | |
530 | } | |
531 | ||
3a15fb6e CB |
532 | static void __put_seccomp_filter(struct seccomp_filter *orig) |
533 | { | |
534 | /* Clean up single-reference branches iteratively. */ | |
535 | while (orig && refcount_dec_and_test(&orig->refs)) { | |
536 | struct seccomp_filter *freeme = orig; | |
537 | orig = orig->prev; | |
538 | seccomp_filter_free(freeme); | |
539 | } | |
540 | } | |
541 | ||
99cdb8b9 CB |
542 | static void __seccomp_filter_release(struct seccomp_filter *orig) |
543 | { | |
544 | /* Notify about any unused filters in the task's former filter tree. */ | |
545 | __seccomp_filter_orphan(orig); | |
546 | /* Finally drop all references to the task's former tree. */ | |
547 | __put_seccomp_filter(orig); | |
548 | } | |
549 | ||
3a15fb6e | 550 | /** |
99cdb8b9 CB |
551 | * seccomp_filter_release - Detach the task from its filter tree, |
552 | * drop its reference count, and notify | |
553 | * about unused filters | |
3a15fb6e CB |
554 | * |
555 | * This function should only be called when the task is exiting as | |
556 | * it detaches it from its filter tree. As such, READ_ONCE() and | |
557 | * barriers are not needed here, as would normally be needed. | |
558 | */ | |
559 | void seccomp_filter_release(struct task_struct *tsk) | |
560 | { | |
561 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
562 | ||
0d8315dd YZ |
563 | /* We are effectively holding the siglock by not having any sighand. */ |
564 | WARN_ON(tsk->sighand != NULL); | |
565 | ||
3a15fb6e CB |
566 | /* Detach task from its filter tree. */ |
567 | tsk->seccomp.filter = NULL; | |
99cdb8b9 | 568 | __seccomp_filter_release(orig); |
3a15fb6e CB |
569 | } |
570 | ||
c2e1f2e3 KC |
571 | /** |
572 | * seccomp_sync_threads: sets all threads to use current's filter | |
573 | * | |
574 | * Expects sighand and cred_guard_mutex locks to be held, and for | |
575 | * seccomp_can_sync_threads() to have returned success already | |
576 | * without dropping the locks. | |
577 | * | |
578 | */ | |
00a02d0c | 579 | static inline void seccomp_sync_threads(unsigned long flags) |
c2e1f2e3 KC |
580 | { |
581 | struct task_struct *thread, *caller; | |
582 | ||
583 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 584 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
585 | |
586 | /* Synchronize all threads. */ | |
587 | caller = current; | |
588 | for_each_thread(caller, thread) { | |
589 | /* Skip current, since it needs no changes. */ | |
590 | if (thread == caller) | |
591 | continue; | |
592 | ||
593 | /* Get a task reference for the new leaf node. */ | |
594 | get_seccomp_filter(caller); | |
99cdb8b9 | 595 | |
c2e1f2e3 KC |
596 | /* |
597 | * Drop the task reference to the shared ancestor since | |
598 | * current's path will hold a reference. (This also | |
599 | * allows a put before the assignment.) | |
600 | */ | |
99cdb8b9 CB |
601 | __seccomp_filter_release(thread->seccomp.filter); |
602 | ||
603 | /* Make our new filter tree visible. */ | |
c2e1f2e3 KC |
604 | smp_store_release(&thread->seccomp.filter, |
605 | caller->seccomp.filter); | |
c818c03b | 606 | atomic_set(&thread->seccomp.filter_count, |
b4d8a58f | 607 | atomic_read(&caller->seccomp.filter_count)); |
103502a3 JH |
608 | |
609 | /* | |
610 | * Don't let an unprivileged task work around | |
611 | * the no_new_privs restriction by creating | |
612 | * a thread that sets it up, enters seccomp, | |
613 | * then dies. | |
614 | */ | |
615 | if (task_no_new_privs(caller)) | |
616 | task_set_no_new_privs(thread); | |
617 | ||
c2e1f2e3 KC |
618 | /* |
619 | * Opt the other thread into seccomp if needed. | |
620 | * As threads are considered to be trust-realm | |
621 | * equivalent (see ptrace_may_access), it is safe to | |
622 | * allow one thread to transition the other. | |
623 | */ | |
103502a3 | 624 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) |
00a02d0c KC |
625 | seccomp_assign_mode(thread, SECCOMP_MODE_FILTER, |
626 | flags); | |
c2e1f2e3 KC |
627 | } |
628 | } | |
629 | ||
e2cfabdf | 630 | /** |
c8bee430 | 631 | * seccomp_prepare_filter: Prepares a seccomp filter for use. |
e2cfabdf WD |
632 | * @fprog: BPF program to install |
633 | * | |
c8bee430 | 634 | * Returns filter on success or an ERR_PTR on failure. |
e2cfabdf | 635 | */ |
c8bee430 | 636 | static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) |
e2cfabdf | 637 | { |
ac67eb2c DB |
638 | struct seccomp_filter *sfilter; |
639 | int ret; | |
8e01b51a YZ |
640 | const bool save_orig = |
641 | #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE) | |
642 | true; | |
643 | #else | |
644 | false; | |
645 | #endif | |
e2cfabdf WD |
646 | |
647 | if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) | |
c8bee430 | 648 | return ERR_PTR(-EINVAL); |
d9e12f42 | 649 | |
c8bee430 | 650 | BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); |
e2cfabdf WD |
651 | |
652 | /* | |
119ce5c8 | 653 | * Installing a seccomp filter requires that the task has |
e2cfabdf WD |
654 | * CAP_SYS_ADMIN in its namespace or be running with no_new_privs. |
655 | * This avoids scenarios where unprivileged tasks can affect the | |
656 | * behavior of privileged children. | |
657 | */ | |
1d4457f9 | 658 | if (!task_no_new_privs(current) && |
fb14528e | 659 | !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN)) |
c8bee430 | 660 | return ERR_PTR(-EACCES); |
e2cfabdf | 661 | |
bd4cf0ed | 662 | /* Allocate a new seccomp_filter */ |
ac67eb2c DB |
663 | sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN); |
664 | if (!sfilter) | |
d9e12f42 | 665 | return ERR_PTR(-ENOMEM); |
ac67eb2c | 666 | |
6a21cc50 | 667 | mutex_init(&sfilter->notify_lock); |
ac67eb2c | 668 | ret = bpf_prog_create_from_user(&sfilter->prog, fprog, |
f8e529ed | 669 | seccomp_check_filter, save_orig); |
ac67eb2c DB |
670 | if (ret < 0) { |
671 | kfree(sfilter); | |
672 | return ERR_PTR(ret); | |
d9e12f42 | 673 | } |
bd4cf0ed | 674 | |
b707ddee | 675 | refcount_set(&sfilter->refs, 1); |
99cdb8b9 | 676 | refcount_set(&sfilter->users, 1); |
76194c4e | 677 | init_waitqueue_head(&sfilter->wqh); |
e2cfabdf | 678 | |
ac67eb2c | 679 | return sfilter; |
e2cfabdf WD |
680 | } |
681 | ||
682 | /** | |
c8bee430 | 683 | * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog |
e2cfabdf WD |
684 | * @user_filter: pointer to the user data containing a sock_fprog. |
685 | * | |
686 | * Returns 0 on success and non-zero otherwise. | |
687 | */ | |
c8bee430 KC |
688 | static struct seccomp_filter * |
689 | seccomp_prepare_user_filter(const char __user *user_filter) | |
e2cfabdf WD |
690 | { |
691 | struct sock_fprog fprog; | |
c8bee430 | 692 | struct seccomp_filter *filter = ERR_PTR(-EFAULT); |
e2cfabdf WD |
693 | |
694 | #ifdef CONFIG_COMPAT | |
5c38065e | 695 | if (in_compat_syscall()) { |
e2cfabdf WD |
696 | struct compat_sock_fprog fprog32; |
697 | if (copy_from_user(&fprog32, user_filter, sizeof(fprog32))) | |
698 | goto out; | |
699 | fprog.len = fprog32.len; | |
700 | fprog.filter = compat_ptr(fprog32.filter); | |
701 | } else /* falls through to the if below. */ | |
702 | #endif | |
703 | if (copy_from_user(&fprog, user_filter, sizeof(fprog))) | |
704 | goto out; | |
c8bee430 | 705 | filter = seccomp_prepare_filter(&fprog); |
e2cfabdf | 706 | out: |
c8bee430 KC |
707 | return filter; |
708 | } | |
709 | ||
8e01b51a YZ |
710 | #ifdef SECCOMP_ARCH_NATIVE |
711 | /** | |
712 | * seccomp_is_const_allow - check if filter is constant allow with given data | |
713 | * @fprog: The BPF programs | |
714 | * @sd: The seccomp data to check against, only syscall number and arch | |
715 | * number are considered constant. | |
716 | */ | |
717 | static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog, | |
718 | struct seccomp_data *sd) | |
719 | { | |
720 | unsigned int reg_value = 0; | |
721 | unsigned int pc; | |
722 | bool op_res; | |
723 | ||
724 | if (WARN_ON_ONCE(!fprog)) | |
725 | return false; | |
726 | ||
727 | for (pc = 0; pc < fprog->len; pc++) { | |
728 | struct sock_filter *insn = &fprog->filter[pc]; | |
729 | u16 code = insn->code; | |
730 | u32 k = insn->k; | |
731 | ||
732 | switch (code) { | |
733 | case BPF_LD | BPF_W | BPF_ABS: | |
734 | switch (k) { | |
735 | case offsetof(struct seccomp_data, nr): | |
736 | reg_value = sd->nr; | |
737 | break; | |
738 | case offsetof(struct seccomp_data, arch): | |
739 | reg_value = sd->arch; | |
740 | break; | |
741 | default: | |
742 | /* can't optimize (non-constant value load) */ | |
743 | return false; | |
744 | } | |
745 | break; | |
746 | case BPF_RET | BPF_K: | |
747 | /* reached return with constant values only, check allow */ | |
748 | return k == SECCOMP_RET_ALLOW; | |
749 | case BPF_JMP | BPF_JA: | |
750 | pc += insn->k; | |
751 | break; | |
752 | case BPF_JMP | BPF_JEQ | BPF_K: | |
753 | case BPF_JMP | BPF_JGE | BPF_K: | |
754 | case BPF_JMP | BPF_JGT | BPF_K: | |
755 | case BPF_JMP | BPF_JSET | BPF_K: | |
756 | switch (BPF_OP(code)) { | |
757 | case BPF_JEQ: | |
758 | op_res = reg_value == k; | |
759 | break; | |
760 | case BPF_JGE: | |
761 | op_res = reg_value >= k; | |
762 | break; | |
763 | case BPF_JGT: | |
764 | op_res = reg_value > k; | |
765 | break; | |
766 | case BPF_JSET: | |
767 | op_res = !!(reg_value & k); | |
768 | break; | |
769 | default: | |
770 | /* can't optimize (unknown jump) */ | |
771 | return false; | |
772 | } | |
773 | ||
774 | pc += op_res ? insn->jt : insn->jf; | |
775 | break; | |
776 | case BPF_ALU | BPF_AND | BPF_K: | |
777 | reg_value &= k; | |
778 | break; | |
779 | default: | |
780 | /* can't optimize (unknown insn) */ | |
781 | return false; | |
782 | } | |
783 | } | |
784 | ||
785 | /* ran off the end of the filter?! */ | |
786 | WARN_ON(1); | |
787 | return false; | |
788 | } | |
789 | ||
790 | static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter, | |
791 | void *bitmap, const void *bitmap_prev, | |
792 | size_t bitmap_size, int arch) | |
793 | { | |
794 | struct sock_fprog_kern *fprog = sfilter->prog->orig_prog; | |
795 | struct seccomp_data sd; | |
796 | int nr; | |
797 | ||
798 | if (bitmap_prev) { | |
799 | /* The new filter must be as restrictive as the last. */ | |
800 | bitmap_copy(bitmap, bitmap_prev, bitmap_size); | |
801 | } else { | |
802 | /* Before any filters, all syscalls are always allowed. */ | |
803 | bitmap_fill(bitmap, bitmap_size); | |
804 | } | |
805 | ||
806 | for (nr = 0; nr < bitmap_size; nr++) { | |
807 | /* No bitmap change: not a cacheable action. */ | |
808 | if (!test_bit(nr, bitmap)) | |
809 | continue; | |
810 | ||
811 | sd.nr = nr; | |
812 | sd.arch = arch; | |
813 | ||
814 | /* No bitmap change: continue to always allow. */ | |
815 | if (seccomp_is_const_allow(fprog, &sd)) | |
816 | continue; | |
817 | ||
818 | /* | |
819 | * Not a cacheable action: always run filters. | |
820 | * atomic clear_bit() not needed, filter not visible yet. | |
821 | */ | |
822 | __clear_bit(nr, bitmap); | |
823 | } | |
824 | } | |
825 | ||
826 | /** | |
a3fc712c | 827 | * seccomp_cache_prepare - emulate the filter to find cacheable syscalls |
8e01b51a YZ |
828 | * @sfilter: The seccomp filter |
829 | * | |
830 | * Returns 0 if successful or -errno if error occurred. | |
831 | */ | |
832 | static void seccomp_cache_prepare(struct seccomp_filter *sfilter) | |
833 | { | |
834 | struct action_cache *cache = &sfilter->cache; | |
835 | const struct action_cache *cache_prev = | |
836 | sfilter->prev ? &sfilter->prev->cache : NULL; | |
837 | ||
838 | seccomp_cache_prepare_bitmap(sfilter, cache->allow_native, | |
839 | cache_prev ? cache_prev->allow_native : NULL, | |
840 | SECCOMP_ARCH_NATIVE_NR, | |
841 | SECCOMP_ARCH_NATIVE); | |
842 | ||
843 | #ifdef SECCOMP_ARCH_COMPAT | |
844 | seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat, | |
845 | cache_prev ? cache_prev->allow_compat : NULL, | |
846 | SECCOMP_ARCH_COMPAT_NR, | |
847 | SECCOMP_ARCH_COMPAT); | |
848 | #endif /* SECCOMP_ARCH_COMPAT */ | |
849 | } | |
850 | #endif /* SECCOMP_ARCH_NATIVE */ | |
851 | ||
c8bee430 KC |
852 | /** |
853 | * seccomp_attach_filter: validate and attach filter | |
854 | * @flags: flags to change filter behavior | |
855 | * @filter: seccomp filter to add to the current process | |
856 | * | |
dbd95212 KC |
857 | * Caller must be holding current->sighand->siglock lock. |
858 | * | |
7a0df7fb TA |
859 | * Returns 0 on success, -ve on error, or |
860 | * - in TSYNC mode: the pid of a thread which was either not in the correct | |
861 | * seccomp mode or did not have an ancestral seccomp filter | |
862 | * - in NEW_LISTENER mode: the fd of the new listener | |
c8bee430 KC |
863 | */ |
864 | static long seccomp_attach_filter(unsigned int flags, | |
865 | struct seccomp_filter *filter) | |
866 | { | |
867 | unsigned long total_insns; | |
868 | struct seccomp_filter *walker; | |
869 | ||
69f6a34b | 870 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 871 | |
c8bee430 KC |
872 | /* Validate resulting filter length. */ |
873 | total_insns = filter->prog->len; | |
874 | for (walker = current->seccomp.filter; walker; walker = walker->prev) | |
875 | total_insns += walker->prog->len + 4; /* 4 instr penalty */ | |
876 | if (total_insns > MAX_INSNS_PER_PATH) | |
877 | return -ENOMEM; | |
878 | ||
c2e1f2e3 KC |
879 | /* If thread sync has been requested, check that it is possible. */ |
880 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) { | |
881 | int ret; | |
882 | ||
883 | ret = seccomp_can_sync_threads(); | |
51891498 TA |
884 | if (ret) { |
885 | if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) | |
886 | return -ESRCH; | |
887 | else | |
888 | return ret; | |
889 | } | |
c2e1f2e3 KC |
890 | } |
891 | ||
e66a3997 TH |
892 | /* Set log flag, if present. */ |
893 | if (flags & SECCOMP_FILTER_FLAG_LOG) | |
894 | filter->log = true; | |
895 | ||
c8bee430 KC |
896 | /* |
897 | * If there is an existing filter, make it the prev and don't drop its | |
898 | * task reference. | |
899 | */ | |
900 | filter->prev = current->seccomp.filter; | |
8e01b51a | 901 | seccomp_cache_prepare(filter); |
c8bee430 | 902 | current->seccomp.filter = filter; |
c818c03b | 903 | atomic_inc(¤t->seccomp.filter_count); |
c8bee430 | 904 | |
c2e1f2e3 KC |
905 | /* Now that the new filter is in place, synchronize to all threads. */ |
906 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) | |
00a02d0c | 907 | seccomp_sync_threads(flags); |
c2e1f2e3 | 908 | |
c8bee430 | 909 | return 0; |
e2cfabdf WD |
910 | } |
911 | ||
084f5601 | 912 | static void __get_seccomp_filter(struct seccomp_filter *filter) |
66a733ea | 913 | { |
b707ddee | 914 | refcount_inc(&filter->refs); |
66a733ea ON |
915 | } |
916 | ||
e2cfabdf WD |
917 | /* get_seccomp_filter - increments the reference count of the filter on @tsk */ |
918 | void get_seccomp_filter(struct task_struct *tsk) | |
919 | { | |
920 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
921 | if (!orig) | |
922 | return; | |
66a733ea | 923 | __get_seccomp_filter(orig); |
99cdb8b9 | 924 | refcount_inc(&orig->users); |
e2cfabdf WD |
925 | } |
926 | ||
e2cfabdf | 927 | #endif /* CONFIG_SECCOMP_FILTER */ |
1da177e4 | 928 | |
0ddec0fc | 929 | /* For use with seccomp_actions_logged */ |
4d3b0b05 KC |
930 | #define SECCOMP_LOG_KILL_PROCESS (1 << 0) |
931 | #define SECCOMP_LOG_KILL_THREAD (1 << 1) | |
0ddec0fc TH |
932 | #define SECCOMP_LOG_TRAP (1 << 2) |
933 | #define SECCOMP_LOG_ERRNO (1 << 3) | |
934 | #define SECCOMP_LOG_TRACE (1 << 4) | |
59f5cf44 TH |
935 | #define SECCOMP_LOG_LOG (1 << 5) |
936 | #define SECCOMP_LOG_ALLOW (1 << 6) | |
6a21cc50 | 937 | #define SECCOMP_LOG_USER_NOTIF (1 << 7) |
0ddec0fc | 938 | |
4d3b0b05 KC |
939 | static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS | |
940 | SECCOMP_LOG_KILL_THREAD | | |
fd76875c KC |
941 | SECCOMP_LOG_TRAP | |
942 | SECCOMP_LOG_ERRNO | | |
6a21cc50 | 943 | SECCOMP_LOG_USER_NOTIF | |
fd76875c | 944 | SECCOMP_LOG_TRACE | |
59f5cf44 | 945 | SECCOMP_LOG_LOG; |
0ddec0fc | 946 | |
e66a3997 TH |
947 | static inline void seccomp_log(unsigned long syscall, long signr, u32 action, |
948 | bool requested) | |
0ddec0fc TH |
949 | { |
950 | bool log = false; | |
951 | ||
952 | switch (action) { | |
953 | case SECCOMP_RET_ALLOW: | |
e66a3997 | 954 | break; |
0ddec0fc | 955 | case SECCOMP_RET_TRAP: |
e66a3997 TH |
956 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP; |
957 | break; | |
0ddec0fc | 958 | case SECCOMP_RET_ERRNO: |
e66a3997 TH |
959 | log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO; |
960 | break; | |
0ddec0fc | 961 | case SECCOMP_RET_TRACE: |
e66a3997 | 962 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE; |
0ddec0fc | 963 | break; |
6a21cc50 TA |
964 | case SECCOMP_RET_USER_NOTIF: |
965 | log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF; | |
966 | break; | |
59f5cf44 TH |
967 | case SECCOMP_RET_LOG: |
968 | log = seccomp_actions_logged & SECCOMP_LOG_LOG; | |
969 | break; | |
fd76875c | 970 | case SECCOMP_RET_KILL_THREAD: |
fd76875c | 971 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD; |
4d3b0b05 KC |
972 | break; |
973 | case SECCOMP_RET_KILL_PROCESS: | |
974 | default: | |
975 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS; | |
0ddec0fc TH |
976 | } |
977 | ||
978 | /* | |
326bee02 TH |
979 | * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the |
980 | * FILTER_FLAG_LOG bit was set. The admin has the ability to silence | |
981 | * any action from being logged by removing the action name from the | |
982 | * seccomp_actions_logged sysctl. | |
0ddec0fc | 983 | */ |
326bee02 TH |
984 | if (!log) |
985 | return; | |
0ddec0fc | 986 | |
326bee02 | 987 | audit_seccomp(syscall, signr, action); |
0ddec0fc TH |
988 | } |
989 | ||
1da177e4 LT |
990 | /* |
991 | * Secure computing mode 1 allows only read/write/exit/sigreturn. | |
992 | * To be fully secure this must be combined with rlimit | |
993 | * to limit the stack allocations too. | |
994 | */ | |
cb4253aa | 995 | static const int mode1_syscalls[] = { |
1da177e4 | 996 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, |
fe4bfff8 | 997 | -1, /* negative terminated */ |
1da177e4 LT |
998 | }; |
999 | ||
a4412fc9 | 1000 | static void __secure_computing_strict(int this_syscall) |
1da177e4 | 1001 | { |
fe4bfff8 | 1002 | const int *allowed_syscalls = mode1_syscalls; |
a4412fc9 | 1003 | #ifdef CONFIG_COMPAT |
5c38065e | 1004 | if (in_compat_syscall()) |
fe4bfff8 | 1005 | allowed_syscalls = get_compat_mode1_syscalls(); |
a4412fc9 AL |
1006 | #endif |
1007 | do { | |
fe4bfff8 | 1008 | if (*allowed_syscalls == this_syscall) |
a4412fc9 | 1009 | return; |
fe4bfff8 | 1010 | } while (*++allowed_syscalls != -1); |
a4412fc9 AL |
1011 | |
1012 | #ifdef SECCOMP_DEBUG | |
1013 | dump_stack(); | |
1014 | #endif | |
495ac306 | 1015 | current->seccomp.mode = SECCOMP_MODE_DEAD; |
fd76875c | 1016 | seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true); |
a4412fc9 AL |
1017 | do_exit(SIGKILL); |
1018 | } | |
1019 | ||
1020 | #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER | |
1021 | void secure_computing_strict(int this_syscall) | |
1022 | { | |
1023 | int mode = current->seccomp.mode; | |
1024 | ||
97f2645f | 1025 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 TA |
1026 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
1027 | return; | |
1028 | ||
221272f9 | 1029 | if (mode == SECCOMP_MODE_DISABLED) |
a4412fc9 AL |
1030 | return; |
1031 | else if (mode == SECCOMP_MODE_STRICT) | |
1032 | __secure_computing_strict(this_syscall); | |
1033 | else | |
1034 | BUG(); | |
1035 | } | |
1036 | #else | |
13aa72f0 AL |
1037 | |
1038 | #ifdef CONFIG_SECCOMP_FILTER | |
6a21cc50 TA |
1039 | static u64 seccomp_next_notify_id(struct seccomp_filter *filter) |
1040 | { | |
1041 | /* | |
1042 | * Note: overflow is ok here, the id just needs to be unique per | |
1043 | * filter. | |
1044 | */ | |
1045 | lockdep_assert_held(&filter->notify_lock); | |
1046 | return filter->notif->next_id++; | |
1047 | } | |
1048 | ||
0ae71c77 | 1049 | static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n) |
7cf97b12 | 1050 | { |
0ae71c77 RC |
1051 | int fd; |
1052 | ||
7cf97b12 SD |
1053 | /* |
1054 | * Remove the notification, and reset the list pointers, indicating | |
1055 | * that it has been handled. | |
1056 | */ | |
1057 | list_del_init(&addfd->list); | |
42eb0d54 | 1058 | if (!addfd->setfd) |
0ae71c77 | 1059 | fd = receive_fd(addfd->file, addfd->flags); |
42eb0d54 | 1060 | else |
0ae71c77 RC |
1061 | fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags); |
1062 | addfd->ret = fd; | |
1063 | ||
1064 | if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) { | |
1065 | /* If we fail reset and return an error to the notifier */ | |
1066 | if (fd < 0) { | |
1067 | n->state = SECCOMP_NOTIFY_SENT; | |
1068 | } else { | |
1069 | /* Return the FD we just added */ | |
1070 | n->flags = 0; | |
1071 | n->error = 0; | |
1072 | n->val = fd; | |
1073 | } | |
1074 | } | |
1075 | ||
1076 | /* | |
1077 | * Mark the notification as completed. From this point, addfd mem | |
1078 | * might be invalidated and we can't safely read it anymore. | |
1079 | */ | |
7cf97b12 SD |
1080 | complete(&addfd->completion); |
1081 | } | |
1082 | ||
fb3c5386 CB |
1083 | static int seccomp_do_user_notification(int this_syscall, |
1084 | struct seccomp_filter *match, | |
1085 | const struct seccomp_data *sd) | |
6a21cc50 TA |
1086 | { |
1087 | int err; | |
fb3c5386 | 1088 | u32 flags = 0; |
6a21cc50 TA |
1089 | long ret = 0; |
1090 | struct seccomp_knotif n = {}; | |
7cf97b12 | 1091 | struct seccomp_kaddfd *addfd, *tmp; |
6a21cc50 TA |
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); | |
4cbf6f62 | 1103 | list_add_tail(&n.list, &match->notif->notifications); |
7cf97b12 | 1104 | INIT_LIST_HEAD(&n.addfd); |
6a21cc50 TA |
1105 | |
1106 | up(&match->notif->request); | |
76194c4e | 1107 | wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM); |
6a21cc50 TA |
1108 | |
1109 | /* | |
1110 | * This is where we wait for a reply from userspace. | |
1111 | */ | |
ddc47391 SD |
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 | ||
7cf97b12 SD |
1119 | addfd = list_first_entry_or_null(&n.addfd, |
1120 | struct seccomp_kaddfd, list); | |
ddc47391 SD |
1121 | /* Check if we were woken up by a addfd message */ |
1122 | if (addfd) | |
0ae71c77 | 1123 | seccomp_handle_addfd(addfd, &n); |
6a21cc50 | 1124 | |
ddc47391 SD |
1125 | } while (n.state != SECCOMP_NOTIFY_REPLIED); |
1126 | ||
1127 | ret = n.val; | |
1128 | err = n.error; | |
1129 | flags = n.flags; | |
1130 | ||
1131 | interrupted: | |
7cf97b12 SD |
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 | ||
6a21cc50 TA |
1140 | /* |
1141 | * Note that it's possible the listener died in between the time when | |
7cf97b12 | 1142 | * we were notified of a response (or a signal) and when we were able to |
6a21cc50 TA |
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); | |
fb3c5386 CB |
1154 | |
1155 | /* Userspace requests to continue the syscall. */ | |
1156 | if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) | |
1157 | return 0; | |
1158 | ||
2d9ca267 | 1159 | syscall_set_return_value(current, current_pt_regs(), |
6a21cc50 | 1160 | err, ret); |
fb3c5386 | 1161 | return -1; |
6a21cc50 TA |
1162 | } |
1163 | ||
ce6526e8 KC |
1164 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
1165 | const bool recheck_after_trace) | |
13aa72f0 AL |
1166 | { |
1167 | u32 filter_ret, action; | |
deb4de8b | 1168 | struct seccomp_filter *match = NULL; |
13aa72f0 | 1169 | int data; |
db511391 | 1170 | struct seccomp_data sd_local; |
1da177e4 | 1171 | |
3ba2530c KC |
1172 | /* |
1173 | * Make sure that any changes to mode from another thread have | |
23d67a54 | 1174 | * been seen after SYSCALL_WORK_SECCOMP was seen. |
3ba2530c | 1175 | */ |
a381b70a | 1176 | smp_rmb(); |
3ba2530c | 1177 | |
db511391 TA |
1178 | if (!sd) { |
1179 | populate_seccomp_data(&sd_local); | |
1180 | sd = &sd_local; | |
1181 | } | |
1182 | ||
deb4de8b | 1183 | filter_ret = seccomp_run_filters(sd, &match); |
13aa72f0 | 1184 | data = filter_ret & SECCOMP_RET_DATA; |
0466bdb9 | 1185 | action = filter_ret & SECCOMP_RET_ACTION_FULL; |
13aa72f0 AL |
1186 | |
1187 | switch (action) { | |
1188 | case SECCOMP_RET_ERRNO: | |
580c57f1 KC |
1189 | /* Set low-order bits as an errno, capped at MAX_ERRNO. */ |
1190 | if (data > MAX_ERRNO) | |
1191 | data = MAX_ERRNO; | |
2d9ca267 | 1192 | syscall_set_return_value(current, current_pt_regs(), |
13aa72f0 AL |
1193 | -data, 0); |
1194 | goto skip; | |
1195 | ||
1196 | case SECCOMP_RET_TRAP: | |
1197 | /* Show the handler the original registers. */ | |
2d9ca267 | 1198 | syscall_rollback(current, current_pt_regs()); |
13aa72f0 | 1199 | /* Let the filter pass back 16 bits of data. */ |
307d522f | 1200 | force_sig_seccomp(this_syscall, data, false); |
13aa72f0 AL |
1201 | goto skip; |
1202 | ||
1203 | case SECCOMP_RET_TRACE: | |
ce6526e8 KC |
1204 | /* We've been put in this state by the ptracer already. */ |
1205 | if (recheck_after_trace) | |
1206 | return 0; | |
1207 | ||
8112c4f1 KC |
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, | |
2d9ca267 | 1211 | current_pt_regs(), |
8112c4f1 KC |
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 | |
485a252a KC |
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. | |
8112c4f1 KC |
1227 | */ |
1228 | if (fatal_signal_pending(current)) | |
485a252a | 1229 | goto skip; |
8112c4f1 | 1230 | /* Check if the tracer forced the syscall to be skipped. */ |
2d9ca267 | 1231 | this_syscall = syscall_get_nr(current, current_pt_regs()); |
8112c4f1 KC |
1232 | if (this_syscall < 0) |
1233 | goto skip; | |
1234 | ||
ce6526e8 KC |
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 | ||
8112c4f1 | 1244 | return 0; |
13aa72f0 | 1245 | |
6a21cc50 | 1246 | case SECCOMP_RET_USER_NOTIF: |
fb3c5386 CB |
1247 | if (seccomp_do_user_notification(this_syscall, match, sd)) |
1248 | goto skip; | |
1249 | ||
1250 | return 0; | |
6a21cc50 | 1251 | |
59f5cf44 TH |
1252 | case SECCOMP_RET_LOG: |
1253 | seccomp_log(this_syscall, 0, action, true); | |
1254 | return 0; | |
1255 | ||
13aa72f0 | 1256 | case SECCOMP_RET_ALLOW: |
deb4de8b KC |
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 | */ | |
8112c4f1 | 1262 | return 0; |
13aa72f0 | 1263 | |
fd76875c | 1264 | case SECCOMP_RET_KILL_THREAD: |
4d3b0b05 | 1265 | case SECCOMP_RET_KILL_PROCESS: |
131b6351 | 1266 | default: |
495ac306 | 1267 | current->seccomp.mode = SECCOMP_MODE_DEAD; |
e66a3997 | 1268 | seccomp_log(this_syscall, SIGSYS, action, true); |
d7276e32 | 1269 | /* Dump core only if this is the last remaining thread. */ |
4d671d92 | 1270 | if (action != SECCOMP_RET_KILL_THREAD || |
d21918e5 | 1271 | (atomic_read(¤t->signal->live) == 1)) { |
d7276e32 | 1272 | /* Show the original registers in the dump. */ |
2d9ca267 | 1273 | syscall_rollback(current, current_pt_regs()); |
307d522f EB |
1274 | /* Trigger a coredump with SIGSYS */ |
1275 | force_sig_seccomp(this_syscall, data, true); | |
1276 | } else { | |
4d3b0b05 | 1277 | do_exit(SIGSYS); |
307d522f EB |
1278 | } |
1279 | return -1; /* skip the syscall go directly to signal handling */ | |
13aa72f0 AL |
1280 | } |
1281 | ||
1282 | unreachable(); | |
1283 | ||
1284 | skip: | |
e66a3997 | 1285 | seccomp_log(this_syscall, 0, action, match ? match->log : false); |
8112c4f1 KC |
1286 | return -1; |
1287 | } | |
1288 | #else | |
ce6526e8 KC |
1289 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
1290 | const bool recheck_after_trace) | |
8112c4f1 KC |
1291 | { |
1292 | BUG(); | |
04b38d01 PC |
1293 | |
1294 | return -1; | |
13aa72f0 | 1295 | } |
1da177e4 | 1296 | #endif |
13aa72f0 | 1297 | |
8112c4f1 | 1298 | int __secure_computing(const struct seccomp_data *sd) |
13aa72f0 AL |
1299 | { |
1300 | int mode = current->seccomp.mode; | |
8112c4f1 | 1301 | int this_syscall; |
13aa72f0 | 1302 | |
97f2645f | 1303 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 | 1304 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
8112c4f1 KC |
1305 | return 0; |
1306 | ||
1307 | this_syscall = sd ? sd->nr : | |
2d9ca267 | 1308 | syscall_get_nr(current, current_pt_regs()); |
13c4a901 | 1309 | |
13aa72f0 | 1310 | switch (mode) { |
e2cfabdf | 1311 | case SECCOMP_MODE_STRICT: |
13aa72f0 | 1312 | __secure_computing_strict(this_syscall); /* may call do_exit */ |
8112c4f1 | 1313 | return 0; |
13aa72f0 | 1314 | case SECCOMP_MODE_FILTER: |
ce6526e8 | 1315 | return __seccomp_filter(this_syscall, sd, false); |
495ac306 KC |
1316 | /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */ |
1317 | case SECCOMP_MODE_DEAD: | |
1318 | WARN_ON_ONCE(1); | |
1319 | do_exit(SIGKILL); | |
1320 | return -1; | |
1da177e4 LT |
1321 | default: |
1322 | BUG(); | |
1323 | } | |
13aa72f0 | 1324 | } |
a4412fc9 | 1325 | #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */ |
1d9d02fe AA |
1326 | |
1327 | long prctl_get_seccomp(void) | |
1328 | { | |
1329 | return current->seccomp.mode; | |
1330 | } | |
1331 | ||
e2cfabdf | 1332 | /** |
3b23dd12 | 1333 | * seccomp_set_mode_strict: internal function for setting strict seccomp |
e2cfabdf WD |
1334 | * |
1335 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
1336 | * | |
1337 | * Returns 0 on success or -EINVAL on failure. | |
1338 | */ | |
3b23dd12 | 1339 | static long seccomp_set_mode_strict(void) |
1d9d02fe | 1340 | { |
3b23dd12 | 1341 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT; |
e2cfabdf | 1342 | long ret = -EINVAL; |
1d9d02fe | 1343 | |
dbd95212 KC |
1344 | spin_lock_irq(¤t->sighand->siglock); |
1345 | ||
1f41b450 | 1346 | if (!seccomp_may_assign_mode(seccomp_mode)) |
1d9d02fe AA |
1347 | goto out; |
1348 | ||
cf99abac | 1349 | #ifdef TIF_NOTSC |
3b23dd12 | 1350 | disable_TSC(); |
cf99abac | 1351 | #endif |
00a02d0c | 1352 | seccomp_assign_mode(current, seccomp_mode, 0); |
3b23dd12 KC |
1353 | ret = 0; |
1354 | ||
1355 | out: | |
dbd95212 | 1356 | spin_unlock_irq(¤t->sighand->siglock); |
3b23dd12 KC |
1357 | |
1358 | return ret; | |
1359 | } | |
1360 | ||
e2cfabdf | 1361 | #ifdef CONFIG_SECCOMP_FILTER |
e8393179 TA |
1362 | static void seccomp_notify_free(struct seccomp_filter *filter) |
1363 | { | |
1364 | kfree(filter->notif); | |
1365 | filter->notif = NULL; | |
1366 | } | |
1367 | ||
a566a901 | 1368 | static void seccomp_notify_detach(struct seccomp_filter *filter) |
6a21cc50 | 1369 | { |
6a21cc50 TA |
1370 | struct seccomp_knotif *knotif; |
1371 | ||
a811dc61 | 1372 | if (!filter) |
a566a901 | 1373 | return; |
a811dc61 | 1374 | |
6a21cc50 TA |
1375 | mutex_lock(&filter->notify_lock); |
1376 | ||
1377 | /* | |
1378 | * If this file is being closed because e.g. the task who owned it | |
1379 | * died, let's wake everyone up who was waiting on us. | |
1380 | */ | |
1381 | list_for_each_entry(knotif, &filter->notif->notifications, list) { | |
1382 | if (knotif->state == SECCOMP_NOTIFY_REPLIED) | |
1383 | continue; | |
1384 | ||
1385 | knotif->state = SECCOMP_NOTIFY_REPLIED; | |
1386 | knotif->error = -ENOSYS; | |
1387 | knotif->val = 0; | |
1388 | ||
7cf97b12 SD |
1389 | /* |
1390 | * We do not need to wake up any pending addfd messages, as | |
1391 | * the notifier will do that for us, as this just looks | |
1392 | * like a standard reply. | |
1393 | */ | |
6a21cc50 TA |
1394 | complete(&knotif->ready); |
1395 | } | |
1396 | ||
e8393179 | 1397 | seccomp_notify_free(filter); |
6a21cc50 | 1398 | mutex_unlock(&filter->notify_lock); |
a566a901 TA |
1399 | } |
1400 | ||
1401 | static int seccomp_notify_release(struct inode *inode, struct file *file) | |
1402 | { | |
1403 | struct seccomp_filter *filter = file->private_data; | |
1404 | ||
1405 | seccomp_notify_detach(filter); | |
6a21cc50 TA |
1406 | __put_seccomp_filter(filter); |
1407 | return 0; | |
1408 | } | |
1409 | ||
9f87dcf1 SD |
1410 | /* must be called with notif_lock held */ |
1411 | static inline struct seccomp_knotif * | |
1412 | find_notification(struct seccomp_filter *filter, u64 id) | |
1413 | { | |
1414 | struct seccomp_knotif *cur; | |
1415 | ||
1416 | lockdep_assert_held(&filter->notify_lock); | |
1417 | ||
1418 | list_for_each_entry(cur, &filter->notif->notifications, list) { | |
1419 | if (cur->id == id) | |
1420 | return cur; | |
1421 | } | |
1422 | ||
1423 | return NULL; | |
1424 | } | |
1425 | ||
1426 | ||
6a21cc50 TA |
1427 | static long seccomp_notify_recv(struct seccomp_filter *filter, |
1428 | void __user *buf) | |
1429 | { | |
1430 | struct seccomp_knotif *knotif = NULL, *cur; | |
1431 | struct seccomp_notif unotif; | |
1432 | ssize_t ret; | |
1433 | ||
2882d53c SD |
1434 | /* Verify that we're not given garbage to keep struct extensible. */ |
1435 | ret = check_zeroed_user(buf, sizeof(unotif)); | |
1436 | if (ret < 0) | |
1437 | return ret; | |
1438 | if (!ret) | |
1439 | return -EINVAL; | |
1440 | ||
6a21cc50 TA |
1441 | memset(&unotif, 0, sizeof(unotif)); |
1442 | ||
1443 | ret = down_interruptible(&filter->notif->request); | |
1444 | if (ret < 0) | |
1445 | return ret; | |
1446 | ||
1447 | mutex_lock(&filter->notify_lock); | |
1448 | list_for_each_entry(cur, &filter->notif->notifications, list) { | |
1449 | if (cur->state == SECCOMP_NOTIFY_INIT) { | |
1450 | knotif = cur; | |
1451 | break; | |
1452 | } | |
1453 | } | |
1454 | ||
1455 | /* | |
1456 | * If we didn't find a notification, it could be that the task was | |
1457 | * interrupted by a fatal signal between the time we were woken and | |
1458 | * when we were able to acquire the rw lock. | |
1459 | */ | |
1460 | if (!knotif) { | |
1461 | ret = -ENOENT; | |
1462 | goto out; | |
1463 | } | |
1464 | ||
1465 | unotif.id = knotif->id; | |
1466 | unotif.pid = task_pid_vnr(knotif->task); | |
1467 | unotif.data = *(knotif->data); | |
1468 | ||
1469 | knotif->state = SECCOMP_NOTIFY_SENT; | |
76194c4e | 1470 | wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM); |
6a21cc50 TA |
1471 | ret = 0; |
1472 | out: | |
1473 | mutex_unlock(&filter->notify_lock); | |
1474 | ||
1475 | if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) { | |
1476 | ret = -EFAULT; | |
1477 | ||
1478 | /* | |
1479 | * Userspace screwed up. To make sure that we keep this | |
1480 | * notification alive, let's reset it back to INIT. It | |
1481 | * may have died when we released the lock, so we need to make | |
1482 | * sure it's still around. | |
1483 | */ | |
6a21cc50 | 1484 | mutex_lock(&filter->notify_lock); |
9f87dcf1 | 1485 | knotif = find_notification(filter, unotif.id); |
6a21cc50 TA |
1486 | if (knotif) { |
1487 | knotif->state = SECCOMP_NOTIFY_INIT; | |
1488 | up(&filter->notif->request); | |
1489 | } | |
1490 | mutex_unlock(&filter->notify_lock); | |
1491 | } | |
1492 | ||
1493 | return ret; | |
1494 | } | |
1495 | ||
1496 | static long seccomp_notify_send(struct seccomp_filter *filter, | |
1497 | void __user *buf) | |
1498 | { | |
1499 | struct seccomp_notif_resp resp = {}; | |
9f87dcf1 | 1500 | struct seccomp_knotif *knotif; |
6a21cc50 TA |
1501 | long ret; |
1502 | ||
1503 | if (copy_from_user(&resp, buf, sizeof(resp))) | |
1504 | return -EFAULT; | |
1505 | ||
fb3c5386 CB |
1506 | if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE) |
1507 | return -EINVAL; | |
1508 | ||
1509 | if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) && | |
1510 | (resp.error || resp.val)) | |
6a21cc50 TA |
1511 | return -EINVAL; |
1512 | ||
1513 | ret = mutex_lock_interruptible(&filter->notify_lock); | |
1514 | if (ret < 0) | |
1515 | return ret; | |
1516 | ||
9f87dcf1 | 1517 | knotif = find_notification(filter, resp.id); |
6a21cc50 TA |
1518 | if (!knotif) { |
1519 | ret = -ENOENT; | |
1520 | goto out; | |
1521 | } | |
1522 | ||
1523 | /* Allow exactly one reply. */ | |
1524 | if (knotif->state != SECCOMP_NOTIFY_SENT) { | |
1525 | ret = -EINPROGRESS; | |
1526 | goto out; | |
1527 | } | |
1528 | ||
1529 | ret = 0; | |
1530 | knotif->state = SECCOMP_NOTIFY_REPLIED; | |
1531 | knotif->error = resp.error; | |
1532 | knotif->val = resp.val; | |
fb3c5386 | 1533 | knotif->flags = resp.flags; |
6a21cc50 TA |
1534 | complete(&knotif->ready); |
1535 | out: | |
1536 | mutex_unlock(&filter->notify_lock); | |
1537 | return ret; | |
1538 | } | |
1539 | ||
1540 | static long seccomp_notify_id_valid(struct seccomp_filter *filter, | |
1541 | void __user *buf) | |
1542 | { | |
9f87dcf1 | 1543 | struct seccomp_knotif *knotif; |
6a21cc50 TA |
1544 | u64 id; |
1545 | long ret; | |
1546 | ||
1547 | if (copy_from_user(&id, buf, sizeof(id))) | |
1548 | return -EFAULT; | |
1549 | ||
1550 | ret = mutex_lock_interruptible(&filter->notify_lock); | |
1551 | if (ret < 0) | |
1552 | return ret; | |
1553 | ||
9f87dcf1 SD |
1554 | knotif = find_notification(filter, id); |
1555 | if (knotif && knotif->state == SECCOMP_NOTIFY_SENT) | |
1556 | ret = 0; | |
1557 | else | |
1558 | ret = -ENOENT; | |
6a21cc50 | 1559 | |
6a21cc50 TA |
1560 | mutex_unlock(&filter->notify_lock); |
1561 | return ret; | |
1562 | } | |
1563 | ||
7cf97b12 SD |
1564 | static long seccomp_notify_addfd(struct seccomp_filter *filter, |
1565 | struct seccomp_notif_addfd __user *uaddfd, | |
1566 | unsigned int size) | |
1567 | { | |
1568 | struct seccomp_notif_addfd addfd; | |
1569 | struct seccomp_knotif *knotif; | |
1570 | struct seccomp_kaddfd kaddfd; | |
1571 | int ret; | |
1572 | ||
1573 | BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0); | |
1574 | BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST); | |
1575 | ||
1576 | if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE) | |
1577 | return -EINVAL; | |
1578 | ||
1579 | ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size); | |
1580 | if (ret) | |
1581 | return ret; | |
1582 | ||
1583 | if (addfd.newfd_flags & ~O_CLOEXEC) | |
1584 | return -EINVAL; | |
1585 | ||
0ae71c77 | 1586 | if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND)) |
7cf97b12 SD |
1587 | return -EINVAL; |
1588 | ||
1589 | if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD)) | |
1590 | return -EINVAL; | |
1591 | ||
1592 | kaddfd.file = fget(addfd.srcfd); | |
1593 | if (!kaddfd.file) | |
1594 | return -EBADF; | |
1595 | ||
0ae71c77 | 1596 | kaddfd.ioctl_flags = addfd.flags; |
7cf97b12 | 1597 | kaddfd.flags = addfd.newfd_flags; |
42eb0d54 CH |
1598 | kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD; |
1599 | kaddfd.fd = addfd.newfd; | |
7cf97b12 SD |
1600 | init_completion(&kaddfd.completion); |
1601 | ||
1602 | ret = mutex_lock_interruptible(&filter->notify_lock); | |
1603 | if (ret < 0) | |
1604 | goto out; | |
1605 | ||
1606 | knotif = find_notification(filter, addfd.id); | |
1607 | if (!knotif) { | |
1608 | ret = -ENOENT; | |
1609 | goto out_unlock; | |
1610 | } | |
1611 | ||
1612 | /* | |
1613 | * We do not want to allow for FD injection to occur before the | |
1614 | * notification has been picked up by a userspace handler, or after | |
1615 | * the notification has been replied to. | |
1616 | */ | |
1617 | if (knotif->state != SECCOMP_NOTIFY_SENT) { | |
1618 | ret = -EINPROGRESS; | |
1619 | goto out_unlock; | |
1620 | } | |
1621 | ||
0ae71c77 RC |
1622 | if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) { |
1623 | /* | |
1624 | * Disallow queuing an atomic addfd + send reply while there are | |
1625 | * some addfd requests still to process. | |
1626 | * | |
1627 | * There is no clear reason to support it and allows us to keep | |
1628 | * the loop on the other side straight-forward. | |
1629 | */ | |
1630 | if (!list_empty(&knotif->addfd)) { | |
1631 | ret = -EBUSY; | |
1632 | goto out_unlock; | |
1633 | } | |
1634 | ||
1635 | /* Allow exactly only one reply */ | |
1636 | knotif->state = SECCOMP_NOTIFY_REPLIED; | |
1637 | } | |
1638 | ||
7cf97b12 SD |
1639 | list_add(&kaddfd.list, &knotif->addfd); |
1640 | complete(&knotif->ready); | |
1641 | mutex_unlock(&filter->notify_lock); | |
1642 | ||
1643 | /* Now we wait for it to be processed or be interrupted */ | |
1644 | ret = wait_for_completion_interruptible(&kaddfd.completion); | |
1645 | if (ret == 0) { | |
1646 | /* | |
1647 | * We had a successful completion. The other side has already | |
1648 | * removed us from the addfd queue, and | |
1649 | * wait_for_completion_interruptible has a memory barrier upon | |
1650 | * success that lets us read this value directly without | |
1651 | * locking. | |
1652 | */ | |
1653 | ret = kaddfd.ret; | |
1654 | goto out; | |
1655 | } | |
1656 | ||
1657 | mutex_lock(&filter->notify_lock); | |
1658 | /* | |
1659 | * Even though we were woken up by a signal and not a successful | |
1660 | * completion, a completion may have happened in the mean time. | |
1661 | * | |
1662 | * We need to check again if the addfd request has been handled, | |
1663 | * and if not, we will remove it from the queue. | |
1664 | */ | |
1665 | if (list_empty(&kaddfd.list)) | |
1666 | ret = kaddfd.ret; | |
1667 | else | |
1668 | list_del(&kaddfd.list); | |
1669 | ||
1670 | out_unlock: | |
1671 | mutex_unlock(&filter->notify_lock); | |
1672 | out: | |
1673 | fput(kaddfd.file); | |
1674 | ||
1675 | return ret; | |
1676 | } | |
1677 | ||
6a21cc50 TA |
1678 | static long seccomp_notify_ioctl(struct file *file, unsigned int cmd, |
1679 | unsigned long arg) | |
1680 | { | |
1681 | struct seccomp_filter *filter = file->private_data; | |
1682 | void __user *buf = (void __user *)arg; | |
1683 | ||
7cf97b12 | 1684 | /* Fixed-size ioctls */ |
6a21cc50 TA |
1685 | switch (cmd) { |
1686 | case SECCOMP_IOCTL_NOTIF_RECV: | |
1687 | return seccomp_notify_recv(filter, buf); | |
1688 | case SECCOMP_IOCTL_NOTIF_SEND: | |
1689 | return seccomp_notify_send(filter, buf); | |
47e33c05 | 1690 | case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR: |
6a21cc50 TA |
1691 | case SECCOMP_IOCTL_NOTIF_ID_VALID: |
1692 | return seccomp_notify_id_valid(filter, buf); | |
7cf97b12 SD |
1693 | } |
1694 | ||
1695 | /* Extensible Argument ioctls */ | |
1696 | #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK)) | |
1697 | switch (EA_IOCTL(cmd)) { | |
1698 | case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD): | |
1699 | return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd)); | |
6a21cc50 TA |
1700 | default: |
1701 | return -EINVAL; | |
1702 | } | |
1703 | } | |
1704 | ||
1705 | static __poll_t seccomp_notify_poll(struct file *file, | |
1706 | struct poll_table_struct *poll_tab) | |
1707 | { | |
1708 | struct seccomp_filter *filter = file->private_data; | |
1709 | __poll_t ret = 0; | |
1710 | struct seccomp_knotif *cur; | |
1711 | ||
76194c4e | 1712 | poll_wait(file, &filter->wqh, poll_tab); |
6a21cc50 | 1713 | |
319deec7 | 1714 | if (mutex_lock_interruptible(&filter->notify_lock) < 0) |
6a21cc50 TA |
1715 | return EPOLLERR; |
1716 | ||
1717 | list_for_each_entry(cur, &filter->notif->notifications, list) { | |
1718 | if (cur->state == SECCOMP_NOTIFY_INIT) | |
1719 | ret |= EPOLLIN | EPOLLRDNORM; | |
1720 | if (cur->state == SECCOMP_NOTIFY_SENT) | |
1721 | ret |= EPOLLOUT | EPOLLWRNORM; | |
1722 | if ((ret & EPOLLIN) && (ret & EPOLLOUT)) | |
1723 | break; | |
1724 | } | |
1725 | ||
1726 | mutex_unlock(&filter->notify_lock); | |
1727 | ||
99cdb8b9 CB |
1728 | if (refcount_read(&filter->users) == 0) |
1729 | ret |= EPOLLHUP; | |
1730 | ||
6a21cc50 TA |
1731 | return ret; |
1732 | } | |
1733 | ||
1734 | static const struct file_operations seccomp_notify_ops = { | |
1735 | .poll = seccomp_notify_poll, | |
1736 | .release = seccomp_notify_release, | |
1737 | .unlocked_ioctl = seccomp_notify_ioctl, | |
3db81afd | 1738 | .compat_ioctl = seccomp_notify_ioctl, |
6a21cc50 TA |
1739 | }; |
1740 | ||
1741 | static struct file *init_listener(struct seccomp_filter *filter) | |
1742 | { | |
dfe719fe | 1743 | struct file *ret; |
6a21cc50 TA |
1744 | |
1745 | ret = ERR_PTR(-ENOMEM); | |
1746 | filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL); | |
1747 | if (!filter->notif) | |
1748 | goto out; | |
1749 | ||
1750 | sema_init(&filter->notif->request, 0); | |
1751 | filter->notif->next_id = get_random_u64(); | |
1752 | INIT_LIST_HEAD(&filter->notif->notifications); | |
6a21cc50 TA |
1753 | |
1754 | ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops, | |
1755 | filter, O_RDWR); | |
1756 | if (IS_ERR(ret)) | |
1757 | goto out_notif; | |
1758 | ||
1759 | /* The file has a reference to it now */ | |
1760 | __get_seccomp_filter(filter); | |
1761 | ||
1762 | out_notif: | |
1763 | if (IS_ERR(ret)) | |
e8393179 | 1764 | seccomp_notify_free(filter); |
6a21cc50 TA |
1765 | out: |
1766 | return ret; | |
1767 | } | |
1768 | ||
dfe719fe JH |
1769 | /* |
1770 | * Does @new_child have a listener while an ancestor also has a listener? | |
1771 | * If so, we'll want to reject this filter. | |
1772 | * This only has to be tested for the current process, even in the TSYNC case, | |
1773 | * because TSYNC installs @child with the same parent on all threads. | |
1774 | * Note that @new_child is not hooked up to its parent at this point yet, so | |
1775 | * we use current->seccomp.filter. | |
1776 | */ | |
1777 | static bool has_duplicate_listener(struct seccomp_filter *new_child) | |
1778 | { | |
1779 | struct seccomp_filter *cur; | |
1780 | ||
1781 | /* must be protected against concurrent TSYNC */ | |
1782 | lockdep_assert_held(¤t->sighand->siglock); | |
1783 | ||
1784 | if (!new_child->notif) | |
1785 | return false; | |
1786 | for (cur = current->seccomp.filter; cur; cur = cur->prev) { | |
1787 | if (cur->notif) | |
1788 | return true; | |
1789 | } | |
1790 | ||
1791 | return false; | |
1792 | } | |
1793 | ||
3b23dd12 KC |
1794 | /** |
1795 | * seccomp_set_mode_filter: internal function for setting seccomp filter | |
48dc92b9 | 1796 | * @flags: flags to change filter behavior |
3b23dd12 KC |
1797 | * @filter: struct sock_fprog containing filter |
1798 | * | |
1799 | * This function may be called repeatedly to install additional filters. | |
1800 | * Every filter successfully installed will be evaluated (in reverse order) | |
1801 | * for each system call the task makes. | |
1802 | * | |
1803 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
1804 | * | |
1805 | * Returns 0 on success or -EINVAL on failure. | |
1806 | */ | |
48dc92b9 KC |
1807 | static long seccomp_set_mode_filter(unsigned int flags, |
1808 | const char __user *filter) | |
3b23dd12 KC |
1809 | { |
1810 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; | |
c8bee430 | 1811 | struct seccomp_filter *prepared = NULL; |
3b23dd12 | 1812 | long ret = -EINVAL; |
6a21cc50 TA |
1813 | int listener = -1; |
1814 | struct file *listener_f = NULL; | |
3b23dd12 | 1815 | |
48dc92b9 | 1816 | /* Validate flags. */ |
c2e1f2e3 | 1817 | if (flags & ~SECCOMP_FILTER_FLAG_MASK) |
dbd95212 | 1818 | return -EINVAL; |
48dc92b9 | 1819 | |
7a0df7fb TA |
1820 | /* |
1821 | * In the successful case, NEW_LISTENER returns the new listener fd. | |
1822 | * But in the failure case, TSYNC returns the thread that died. If you | |
1823 | * combine these two flags, there's no way to tell whether something | |
51891498 TA |
1824 | * succeeded or failed. So, let's disallow this combination if the user |
1825 | * has not explicitly requested no errors from TSYNC. | |
7a0df7fb TA |
1826 | */ |
1827 | if ((flags & SECCOMP_FILTER_FLAG_TSYNC) && | |
51891498 TA |
1828 | (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) && |
1829 | ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0)) | |
7a0df7fb TA |
1830 | return -EINVAL; |
1831 | ||
c8bee430 KC |
1832 | /* Prepare the new filter before holding any locks. */ |
1833 | prepared = seccomp_prepare_user_filter(filter); | |
1834 | if (IS_ERR(prepared)) | |
1835 | return PTR_ERR(prepared); | |
1836 | ||
6a21cc50 TA |
1837 | if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) { |
1838 | listener = get_unused_fd_flags(O_CLOEXEC); | |
1839 | if (listener < 0) { | |
1840 | ret = listener; | |
1841 | goto out_free; | |
1842 | } | |
1843 | ||
1844 | listener_f = init_listener(prepared); | |
1845 | if (IS_ERR(listener_f)) { | |
1846 | put_unused_fd(listener); | |
1847 | ret = PTR_ERR(listener_f); | |
1848 | goto out_free; | |
1849 | } | |
1850 | } | |
1851 | ||
c2e1f2e3 KC |
1852 | /* |
1853 | * Make sure we cannot change seccomp or nnp state via TSYNC | |
1854 | * while another thread is in the middle of calling exec. | |
1855 | */ | |
1856 | if (flags & SECCOMP_FILTER_FLAG_TSYNC && | |
1857 | mutex_lock_killable(¤t->signal->cred_guard_mutex)) | |
6a21cc50 | 1858 | goto out_put_fd; |
c2e1f2e3 | 1859 | |
dbd95212 KC |
1860 | spin_lock_irq(¤t->sighand->siglock); |
1861 | ||
3b23dd12 KC |
1862 | if (!seccomp_may_assign_mode(seccomp_mode)) |
1863 | goto out; | |
1864 | ||
dfe719fe JH |
1865 | if (has_duplicate_listener(prepared)) { |
1866 | ret = -EBUSY; | |
1867 | goto out; | |
1868 | } | |
1869 | ||
c8bee430 | 1870 | ret = seccomp_attach_filter(flags, prepared); |
3b23dd12 | 1871 | if (ret) |
e2cfabdf | 1872 | goto out; |
c8bee430 KC |
1873 | /* Do not free the successfully attached filter. */ |
1874 | prepared = NULL; | |
1d9d02fe | 1875 | |
00a02d0c | 1876 | seccomp_assign_mode(current, seccomp_mode, flags); |
e2cfabdf | 1877 | out: |
dbd95212 | 1878 | spin_unlock_irq(¤t->sighand->siglock); |
c2e1f2e3 KC |
1879 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) |
1880 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
6a21cc50 TA |
1881 | out_put_fd: |
1882 | if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) { | |
7a0df7fb | 1883 | if (ret) { |
a811dc61 | 1884 | listener_f->private_data = NULL; |
6a21cc50 TA |
1885 | fput(listener_f); |
1886 | put_unused_fd(listener); | |
a566a901 | 1887 | seccomp_notify_detach(prepared); |
6a21cc50 TA |
1888 | } else { |
1889 | fd_install(listener, listener_f); | |
1890 | ret = listener; | |
1891 | } | |
1892 | } | |
c2e1f2e3 | 1893 | out_free: |
c8bee430 | 1894 | seccomp_filter_free(prepared); |
1d9d02fe AA |
1895 | return ret; |
1896 | } | |
3b23dd12 | 1897 | #else |
48dc92b9 KC |
1898 | static inline long seccomp_set_mode_filter(unsigned int flags, |
1899 | const char __user *filter) | |
3b23dd12 KC |
1900 | { |
1901 | return -EINVAL; | |
1902 | } | |
1903 | #endif | |
d78ab02c | 1904 | |
d612b1fd TH |
1905 | static long seccomp_get_action_avail(const char __user *uaction) |
1906 | { | |
1907 | u32 action; | |
1908 | ||
1909 | if (copy_from_user(&action, uaction, sizeof(action))) | |
1910 | return -EFAULT; | |
1911 | ||
1912 | switch (action) { | |
0466bdb9 | 1913 | case SECCOMP_RET_KILL_PROCESS: |
fd76875c | 1914 | case SECCOMP_RET_KILL_THREAD: |
d612b1fd TH |
1915 | case SECCOMP_RET_TRAP: |
1916 | case SECCOMP_RET_ERRNO: | |
6a21cc50 | 1917 | case SECCOMP_RET_USER_NOTIF: |
d612b1fd | 1918 | case SECCOMP_RET_TRACE: |
59f5cf44 | 1919 | case SECCOMP_RET_LOG: |
d612b1fd TH |
1920 | case SECCOMP_RET_ALLOW: |
1921 | break; | |
1922 | default: | |
1923 | return -EOPNOTSUPP; | |
1924 | } | |
1925 | ||
1926 | return 0; | |
1927 | } | |
1928 | ||
6a21cc50 TA |
1929 | static long seccomp_get_notif_sizes(void __user *usizes) |
1930 | { | |
1931 | struct seccomp_notif_sizes sizes = { | |
1932 | .seccomp_notif = sizeof(struct seccomp_notif), | |
1933 | .seccomp_notif_resp = sizeof(struct seccomp_notif_resp), | |
1934 | .seccomp_data = sizeof(struct seccomp_data), | |
1935 | }; | |
1936 | ||
1937 | if (copy_to_user(usizes, &sizes, sizeof(sizes))) | |
1938 | return -EFAULT; | |
1939 | ||
1940 | return 0; | |
1941 | } | |
1942 | ||
48dc92b9 KC |
1943 | /* Common entry point for both prctl and syscall. */ |
1944 | static long do_seccomp(unsigned int op, unsigned int flags, | |
a5662e4d | 1945 | void __user *uargs) |
48dc92b9 KC |
1946 | { |
1947 | switch (op) { | |
1948 | case SECCOMP_SET_MODE_STRICT: | |
1949 | if (flags != 0 || uargs != NULL) | |
1950 | return -EINVAL; | |
1951 | return seccomp_set_mode_strict(); | |
1952 | case SECCOMP_SET_MODE_FILTER: | |
1953 | return seccomp_set_mode_filter(flags, uargs); | |
d612b1fd TH |
1954 | case SECCOMP_GET_ACTION_AVAIL: |
1955 | if (flags != 0) | |
1956 | return -EINVAL; | |
1957 | ||
1958 | return seccomp_get_action_avail(uargs); | |
6a21cc50 TA |
1959 | case SECCOMP_GET_NOTIF_SIZES: |
1960 | if (flags != 0) | |
1961 | return -EINVAL; | |
1962 | ||
1963 | return seccomp_get_notif_sizes(uargs); | |
48dc92b9 KC |
1964 | default: |
1965 | return -EINVAL; | |
1966 | } | |
1967 | } | |
1968 | ||
1969 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, | |
a5662e4d | 1970 | void __user *, uargs) |
48dc92b9 KC |
1971 | { |
1972 | return do_seccomp(op, flags, uargs); | |
1973 | } | |
1974 | ||
d78ab02c KC |
1975 | /** |
1976 | * prctl_set_seccomp: configures current->seccomp.mode | |
1977 | * @seccomp_mode: requested mode to use | |
1978 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER | |
1979 | * | |
1980 | * Returns 0 on success or -EINVAL on failure. | |
1981 | */ | |
a5662e4d | 1982 | long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter) |
d78ab02c | 1983 | { |
48dc92b9 | 1984 | unsigned int op; |
a5662e4d | 1985 | void __user *uargs; |
48dc92b9 | 1986 | |
3b23dd12 KC |
1987 | switch (seccomp_mode) { |
1988 | case SECCOMP_MODE_STRICT: | |
48dc92b9 KC |
1989 | op = SECCOMP_SET_MODE_STRICT; |
1990 | /* | |
1991 | * Setting strict mode through prctl always ignored filter, | |
1992 | * so make sure it is always NULL here to pass the internal | |
1993 | * check in do_seccomp(). | |
1994 | */ | |
1995 | uargs = NULL; | |
1996 | break; | |
3b23dd12 | 1997 | case SECCOMP_MODE_FILTER: |
48dc92b9 KC |
1998 | op = SECCOMP_SET_MODE_FILTER; |
1999 | uargs = filter; | |
2000 | break; | |
3b23dd12 KC |
2001 | default: |
2002 | return -EINVAL; | |
2003 | } | |
48dc92b9 KC |
2004 | |
2005 | /* prctl interface doesn't have flags, so they are always zero. */ | |
2006 | return do_seccomp(op, 0, uargs); | |
d78ab02c | 2007 | } |
f8e529ed TA |
2008 | |
2009 | #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) | |
f06eae83 TA |
2010 | static struct seccomp_filter *get_nth_filter(struct task_struct *task, |
2011 | unsigned long filter_off) | |
f8e529ed | 2012 | { |
f06eae83 TA |
2013 | struct seccomp_filter *orig, *filter; |
2014 | unsigned long count; | |
f8e529ed | 2015 | |
f06eae83 TA |
2016 | /* |
2017 | * Note: this is only correct because the caller should be the (ptrace) | |
2018 | * tracer of the task, otherwise lock_task_sighand is needed. | |
2019 | */ | |
f8e529ed | 2020 | spin_lock_irq(&task->sighand->siglock); |
f06eae83 | 2021 | |
f8e529ed | 2022 | if (task->seccomp.mode != SECCOMP_MODE_FILTER) { |
f06eae83 TA |
2023 | spin_unlock_irq(&task->sighand->siglock); |
2024 | return ERR_PTR(-EINVAL); | |
f8e529ed TA |
2025 | } |
2026 | ||
f06eae83 TA |
2027 | orig = task->seccomp.filter; |
2028 | __get_seccomp_filter(orig); | |
2029 | spin_unlock_irq(&task->sighand->siglock); | |
2030 | ||
2031 | count = 0; | |
2032 | for (filter = orig; filter; filter = filter->prev) | |
f8e529ed | 2033 | count++; |
f8e529ed TA |
2034 | |
2035 | if (filter_off >= count) { | |
f06eae83 | 2036 | filter = ERR_PTR(-ENOENT); |
f8e529ed TA |
2037 | goto out; |
2038 | } | |
f8e529ed | 2039 | |
f06eae83 TA |
2040 | count -= filter_off; |
2041 | for (filter = orig; filter && count > 1; filter = filter->prev) | |
f8e529ed | 2042 | count--; |
f8e529ed TA |
2043 | |
2044 | if (WARN_ON(count != 1 || !filter)) { | |
f06eae83 | 2045 | filter = ERR_PTR(-ENOENT); |
f8e529ed TA |
2046 | goto out; |
2047 | } | |
2048 | ||
f06eae83 TA |
2049 | __get_seccomp_filter(filter); |
2050 | ||
2051 | out: | |
2052 | __put_seccomp_filter(orig); | |
2053 | return filter; | |
2054 | } | |
2055 | ||
2056 | long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, | |
2057 | void __user *data) | |
2058 | { | |
2059 | struct seccomp_filter *filter; | |
2060 | struct sock_fprog_kern *fprog; | |
2061 | long ret; | |
2062 | ||
2063 | if (!capable(CAP_SYS_ADMIN) || | |
2064 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { | |
2065 | return -EACCES; | |
2066 | } | |
2067 | ||
2068 | filter = get_nth_filter(task, filter_off); | |
2069 | if (IS_ERR(filter)) | |
2070 | return PTR_ERR(filter); | |
2071 | ||
f8e529ed TA |
2072 | fprog = filter->prog->orig_prog; |
2073 | if (!fprog) { | |
470bf1f2 | 2074 | /* This must be a new non-cBPF filter, since we save |
f8e529ed TA |
2075 | * every cBPF filter's orig_prog above when |
2076 | * CONFIG_CHECKPOINT_RESTORE is enabled. | |
2077 | */ | |
2078 | ret = -EMEDIUMTYPE; | |
2079 | goto out; | |
2080 | } | |
2081 | ||
2082 | ret = fprog->len; | |
2083 | if (!data) | |
2084 | goto out; | |
2085 | ||
f8e529ed TA |
2086 | if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog))) |
2087 | ret = -EFAULT; | |
2088 | ||
f8e529ed | 2089 | out: |
66a733ea | 2090 | __put_seccomp_filter(filter); |
f8e529ed | 2091 | return ret; |
f8e529ed | 2092 | } |
f8e529ed | 2093 | |
26500475 TA |
2094 | long seccomp_get_metadata(struct task_struct *task, |
2095 | unsigned long size, void __user *data) | |
2096 | { | |
2097 | long ret; | |
2098 | struct seccomp_filter *filter; | |
2099 | struct seccomp_metadata kmd = {}; | |
2100 | ||
2101 | if (!capable(CAP_SYS_ADMIN) || | |
2102 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { | |
2103 | return -EACCES; | |
2104 | } | |
2105 | ||
2106 | size = min_t(unsigned long, size, sizeof(kmd)); | |
2107 | ||
63bb0045 TA |
2108 | if (size < sizeof(kmd.filter_off)) |
2109 | return -EINVAL; | |
2110 | ||
2111 | if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off))) | |
26500475 TA |
2112 | return -EFAULT; |
2113 | ||
2114 | filter = get_nth_filter(task, kmd.filter_off); | |
2115 | if (IS_ERR(filter)) | |
2116 | return PTR_ERR(filter); | |
2117 | ||
26500475 TA |
2118 | if (filter->log) |
2119 | kmd.flags |= SECCOMP_FILTER_FLAG_LOG; | |
2120 | ||
2121 | ret = size; | |
2122 | if (copy_to_user(data, &kmd, size)) | |
2123 | ret = -EFAULT; | |
2124 | ||
2125 | __put_seccomp_filter(filter); | |
f8e529ed TA |
2126 | return ret; |
2127 | } | |
2128 | #endif | |
8e5f1ad1 TH |
2129 | |
2130 | #ifdef CONFIG_SYSCTL | |
2131 | ||
2132 | /* Human readable action names for friendly sysctl interaction */ | |
0466bdb9 | 2133 | #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process" |
fd76875c | 2134 | #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread" |
8e5f1ad1 TH |
2135 | #define SECCOMP_RET_TRAP_NAME "trap" |
2136 | #define SECCOMP_RET_ERRNO_NAME "errno" | |
6a21cc50 | 2137 | #define SECCOMP_RET_USER_NOTIF_NAME "user_notif" |
8e5f1ad1 | 2138 | #define SECCOMP_RET_TRACE_NAME "trace" |
59f5cf44 | 2139 | #define SECCOMP_RET_LOG_NAME "log" |
8e5f1ad1 TH |
2140 | #define SECCOMP_RET_ALLOW_NAME "allow" |
2141 | ||
fd76875c | 2142 | static const char seccomp_actions_avail[] = |
0466bdb9 | 2143 | SECCOMP_RET_KILL_PROCESS_NAME " " |
fd76875c KC |
2144 | SECCOMP_RET_KILL_THREAD_NAME " " |
2145 | SECCOMP_RET_TRAP_NAME " " | |
2146 | SECCOMP_RET_ERRNO_NAME " " | |
6a21cc50 | 2147 | SECCOMP_RET_USER_NOTIF_NAME " " |
fd76875c KC |
2148 | SECCOMP_RET_TRACE_NAME " " |
2149 | SECCOMP_RET_LOG_NAME " " | |
2150 | SECCOMP_RET_ALLOW_NAME; | |
8e5f1ad1 | 2151 | |
0ddec0fc TH |
2152 | struct seccomp_log_name { |
2153 | u32 log; | |
2154 | const char *name; | |
2155 | }; | |
2156 | ||
2157 | static const struct seccomp_log_name seccomp_log_names[] = { | |
0466bdb9 | 2158 | { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME }, |
fd76875c | 2159 | { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME }, |
0ddec0fc TH |
2160 | { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME }, |
2161 | { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME }, | |
6a21cc50 | 2162 | { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME }, |
0ddec0fc | 2163 | { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME }, |
59f5cf44 | 2164 | { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME }, |
0ddec0fc TH |
2165 | { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME }, |
2166 | { } | |
2167 | }; | |
2168 | ||
2169 | static bool seccomp_names_from_actions_logged(char *names, size_t size, | |
beb44aca TH |
2170 | u32 actions_logged, |
2171 | const char *sep) | |
0ddec0fc TH |
2172 | { |
2173 | const struct seccomp_log_name *cur; | |
beb44aca | 2174 | bool append_sep = false; |
0ddec0fc TH |
2175 | |
2176 | for (cur = seccomp_log_names; cur->name && size; cur++) { | |
2177 | ssize_t ret; | |
2178 | ||
2179 | if (!(actions_logged & cur->log)) | |
2180 | continue; | |
2181 | ||
beb44aca TH |
2182 | if (append_sep) { |
2183 | ret = strscpy(names, sep, size); | |
0ddec0fc TH |
2184 | if (ret < 0) |
2185 | return false; | |
2186 | ||
2187 | names += ret; | |
2188 | size -= ret; | |
2189 | } else | |
beb44aca | 2190 | append_sep = true; |
0ddec0fc TH |
2191 | |
2192 | ret = strscpy(names, cur->name, size); | |
2193 | if (ret < 0) | |
2194 | return false; | |
2195 | ||
2196 | names += ret; | |
2197 | size -= ret; | |
2198 | } | |
2199 | ||
2200 | return true; | |
2201 | } | |
2202 | ||
2203 | static bool seccomp_action_logged_from_name(u32 *action_logged, | |
2204 | const char *name) | |
2205 | { | |
2206 | const struct seccomp_log_name *cur; | |
2207 | ||
2208 | for (cur = seccomp_log_names; cur->name; cur++) { | |
2209 | if (!strcmp(cur->name, name)) { | |
2210 | *action_logged = cur->log; | |
2211 | return true; | |
2212 | } | |
2213 | } | |
2214 | ||
2215 | return false; | |
2216 | } | |
2217 | ||
2218 | static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names) | |
2219 | { | |
2220 | char *name; | |
2221 | ||
2222 | *actions_logged = 0; | |
2223 | while ((name = strsep(&names, " ")) && *name) { | |
2224 | u32 action_logged = 0; | |
2225 | ||
2226 | if (!seccomp_action_logged_from_name(&action_logged, name)) | |
2227 | return false; | |
2228 | ||
2229 | *actions_logged |= action_logged; | |
2230 | } | |
2231 | ||
2232 | return true; | |
2233 | } | |
2234 | ||
fab686eb | 2235 | static int read_actions_logged(struct ctl_table *ro_table, void *buffer, |
d013db02 | 2236 | size_t *lenp, loff_t *ppos) |
0ddec0fc TH |
2237 | { |
2238 | char names[sizeof(seccomp_actions_avail)]; | |
2239 | struct ctl_table table; | |
d013db02 TH |
2240 | |
2241 | memset(names, 0, sizeof(names)); | |
2242 | ||
2243 | if (!seccomp_names_from_actions_logged(names, sizeof(names), | |
beb44aca | 2244 | seccomp_actions_logged, " ")) |
d013db02 TH |
2245 | return -EINVAL; |
2246 | ||
2247 | table = *ro_table; | |
2248 | table.data = names; | |
2249 | table.maxlen = sizeof(names); | |
2250 | return proc_dostring(&table, 0, buffer, lenp, ppos); | |
2251 | } | |
2252 | ||
fab686eb | 2253 | static int write_actions_logged(struct ctl_table *ro_table, void *buffer, |
ea6eca77 | 2254 | size_t *lenp, loff_t *ppos, u32 *actions_logged) |
0ddec0fc TH |
2255 | { |
2256 | char names[sizeof(seccomp_actions_avail)]; | |
2257 | struct ctl_table table; | |
2258 | int ret; | |
2259 | ||
d013db02 | 2260 | if (!capable(CAP_SYS_ADMIN)) |
0ddec0fc TH |
2261 | return -EPERM; |
2262 | ||
2263 | memset(names, 0, sizeof(names)); | |
2264 | ||
0ddec0fc TH |
2265 | table = *ro_table; |
2266 | table.data = names; | |
2267 | table.maxlen = sizeof(names); | |
d013db02 | 2268 | ret = proc_dostring(&table, 1, buffer, lenp, ppos); |
0ddec0fc TH |
2269 | if (ret) |
2270 | return ret; | |
2271 | ||
ea6eca77 | 2272 | if (!seccomp_actions_logged_from_names(actions_logged, table.data)) |
d013db02 | 2273 | return -EINVAL; |
0ddec0fc | 2274 | |
ea6eca77 | 2275 | if (*actions_logged & SECCOMP_LOG_ALLOW) |
d013db02 | 2276 | return -EINVAL; |
0ddec0fc | 2277 | |
ea6eca77 | 2278 | seccomp_actions_logged = *actions_logged; |
0ddec0fc TH |
2279 | return 0; |
2280 | } | |
0ddec0fc | 2281 | |
ea6eca77 TH |
2282 | static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged, |
2283 | int ret) | |
2284 | { | |
2285 | char names[sizeof(seccomp_actions_avail)]; | |
2286 | char old_names[sizeof(seccomp_actions_avail)]; | |
2287 | const char *new = names; | |
2288 | const char *old = old_names; | |
0ddec0fc | 2289 | |
ea6eca77 TH |
2290 | if (!audit_enabled) |
2291 | return; | |
2292 | ||
2293 | memset(names, 0, sizeof(names)); | |
2294 | memset(old_names, 0, sizeof(old_names)); | |
2295 | ||
2296 | if (ret) | |
2297 | new = "?"; | |
2298 | else if (!actions_logged) | |
2299 | new = "(none)"; | |
2300 | else if (!seccomp_names_from_actions_logged(names, sizeof(names), | |
2301 | actions_logged, ",")) | |
2302 | new = "?"; | |
2303 | ||
2304 | if (!old_actions_logged) | |
2305 | old = "(none)"; | |
2306 | else if (!seccomp_names_from_actions_logged(old_names, | |
2307 | sizeof(old_names), | |
2308 | old_actions_logged, ",")) | |
2309 | old = "?"; | |
2310 | ||
2311 | return audit_seccomp_actions_logged(new, old, !ret); | |
2312 | } | |
2313 | ||
d013db02 | 2314 | static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, |
32927393 | 2315 | void *buffer, size_t *lenp, |
d013db02 TH |
2316 | loff_t *ppos) |
2317 | { | |
ea6eca77 TH |
2318 | int ret; |
2319 | ||
2320 | if (write) { | |
2321 | u32 actions_logged = 0; | |
2322 | u32 old_actions_logged = seccomp_actions_logged; | |
2323 | ||
2324 | ret = write_actions_logged(ro_table, buffer, lenp, ppos, | |
2325 | &actions_logged); | |
2326 | audit_actions_logged(actions_logged, old_actions_logged, ret); | |
2327 | } else | |
2328 | ret = read_actions_logged(ro_table, buffer, lenp, ppos); | |
2329 | ||
2330 | return ret; | |
0ddec0fc TH |
2331 | } |
2332 | ||
8e5f1ad1 TH |
2333 | static struct ctl_path seccomp_sysctl_path[] = { |
2334 | { .procname = "kernel", }, | |
2335 | { .procname = "seccomp", }, | |
2336 | { } | |
2337 | }; | |
2338 | ||
2339 | static struct ctl_table seccomp_sysctl_table[] = { | |
2340 | { | |
2341 | .procname = "actions_avail", | |
2342 | .data = (void *) &seccomp_actions_avail, | |
2343 | .maxlen = sizeof(seccomp_actions_avail), | |
2344 | .mode = 0444, | |
2345 | .proc_handler = proc_dostring, | |
2346 | }, | |
0ddec0fc TH |
2347 | { |
2348 | .procname = "actions_logged", | |
2349 | .mode = 0644, | |
2350 | .proc_handler = seccomp_actions_logged_handler, | |
2351 | }, | |
8e5f1ad1 TH |
2352 | { } |
2353 | }; | |
2354 | ||
2355 | static int __init seccomp_sysctl_init(void) | |
2356 | { | |
2357 | struct ctl_table_header *hdr; | |
2358 | ||
2359 | hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table); | |
2360 | if (!hdr) | |
e68f9d49 | 2361 | pr_warn("sysctl registration failed\n"); |
8e5f1ad1 TH |
2362 | else |
2363 | kmemleak_not_leak(hdr); | |
2364 | ||
2365 | return 0; | |
2366 | } | |
2367 | ||
2368 | device_initcall(seccomp_sysctl_init) | |
2369 | ||
2370 | #endif /* CONFIG_SYSCTL */ | |
0d8315dd YZ |
2371 | |
2372 | #ifdef CONFIG_SECCOMP_CACHE_DEBUG | |
2373 | /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */ | |
2374 | static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name, | |
2375 | const void *bitmap, size_t bitmap_size) | |
2376 | { | |
2377 | int nr; | |
2378 | ||
2379 | for (nr = 0; nr < bitmap_size; nr++) { | |
2380 | bool cached = test_bit(nr, bitmap); | |
2381 | char *status = cached ? "ALLOW" : "FILTER"; | |
2382 | ||
2383 | seq_printf(m, "%s %d %s\n", name, nr, status); | |
2384 | } | |
2385 | } | |
2386 | ||
2387 | int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns, | |
2388 | struct pid *pid, struct task_struct *task) | |
2389 | { | |
2390 | struct seccomp_filter *f; | |
2391 | unsigned long flags; | |
2392 | ||
2393 | /* | |
2394 | * We don't want some sandboxed process to know what their seccomp | |
2395 | * filters consist of. | |
2396 | */ | |
2397 | if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN)) | |
2398 | return -EACCES; | |
2399 | ||
2400 | if (!lock_task_sighand(task, &flags)) | |
2401 | return -ESRCH; | |
2402 | ||
2403 | f = READ_ONCE(task->seccomp.filter); | |
2404 | if (!f) { | |
2405 | unlock_task_sighand(task, &flags); | |
2406 | return 0; | |
2407 | } | |
2408 | ||
2409 | /* prevent filter from being freed while we are printing it */ | |
2410 | __get_seccomp_filter(f); | |
2411 | unlock_task_sighand(task, &flags); | |
2412 | ||
2413 | proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME, | |
2414 | f->cache.allow_native, | |
2415 | SECCOMP_ARCH_NATIVE_NR); | |
2416 | ||
2417 | #ifdef SECCOMP_ARCH_COMPAT | |
2418 | proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME, | |
2419 | f->cache.allow_compat, | |
2420 | SECCOMP_ARCH_COMPAT_NR); | |
2421 | #endif /* SECCOMP_ARCH_COMPAT */ | |
2422 | ||
2423 | __put_seccomp_filter(f); | |
2424 | return 0; | |
2425 | } | |
2426 | #endif /* CONFIG_SECCOMP_CACHE_DEBUG */ |