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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 LT |
15 | */ |
16 | ||
0b5fa229 | 17 | #include <linux/refcount.h> |
85e7bac3 | 18 | #include <linux/audit.h> |
5b101740 | 19 | #include <linux/compat.h> |
b25e6716 | 20 | #include <linux/coredump.h> |
8e5f1ad1 | 21 | #include <linux/kmemleak.h> |
5c307089 KC |
22 | #include <linux/nospec.h> |
23 | #include <linux/prctl.h> | |
e2cfabdf | 24 | #include <linux/sched.h> |
68db0cf1 | 25 | #include <linux/sched/task_stack.h> |
e2cfabdf | 26 | #include <linux/seccomp.h> |
c8bee430 | 27 | #include <linux/slab.h> |
48dc92b9 | 28 | #include <linux/syscalls.h> |
8e5f1ad1 | 29 | #include <linux/sysctl.h> |
1da177e4 | 30 | |
a4412fc9 | 31 | #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER |
e2cfabdf | 32 | #include <asm/syscall.h> |
a4412fc9 | 33 | #endif |
e2cfabdf WD |
34 | |
35 | #ifdef CONFIG_SECCOMP_FILTER | |
e2cfabdf | 36 | #include <linux/filter.h> |
c2e1f2e3 | 37 | #include <linux/pid.h> |
fb0fadf9 | 38 | #include <linux/ptrace.h> |
e2cfabdf | 39 | #include <linux/security.h> |
e2cfabdf WD |
40 | #include <linux/tracehook.h> |
41 | #include <linux/uaccess.h> | |
42 | ||
43 | /** | |
44 | * struct seccomp_filter - container for seccomp BPF programs | |
45 | * | |
46 | * @usage: reference count to manage the object lifetime. | |
47 | * get/put helpers should be used when accessing an instance | |
48 | * outside of a lifetime-guarded section. In general, this | |
49 | * is only needed for handling filters shared across tasks. | |
e66a3997 | 50 | * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged |
e2cfabdf | 51 | * @prev: points to a previously installed, or inherited, filter |
285fdfc5 | 52 | * @prog: the BPF program to evaluate |
e2cfabdf WD |
53 | * |
54 | * seccomp_filter objects are organized in a tree linked via the @prev | |
55 | * pointer. For any task, it appears to be a singly-linked list starting | |
56 | * with current->seccomp.filter, the most recently attached or inherited filter. | |
57 | * However, multiple filters may share a @prev node, by way of fork(), which | |
58 | * results in a unidirectional tree existing in memory. This is similar to | |
59 | * how namespaces work. | |
60 | * | |
61 | * seccomp_filter objects should never be modified after being attached | |
62 | * to a task_struct (other than @usage). | |
63 | */ | |
64 | struct seccomp_filter { | |
0b5fa229 | 65 | refcount_t usage; |
e66a3997 | 66 | bool log; |
e2cfabdf | 67 | struct seccomp_filter *prev; |
7ae457c1 | 68 | struct bpf_prog *prog; |
e2cfabdf WD |
69 | }; |
70 | ||
71 | /* Limit any path through the tree to 256KB worth of instructions. */ | |
72 | #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) | |
73 | ||
bd4cf0ed | 74 | /* |
e2cfabdf WD |
75 | * Endianness is explicitly ignored and left for BPF program authors to manage |
76 | * as per the specific architecture. | |
77 | */ | |
bd4cf0ed | 78 | static void populate_seccomp_data(struct seccomp_data *sd) |
e2cfabdf | 79 | { |
bd4cf0ed AS |
80 | struct task_struct *task = current; |
81 | struct pt_regs *regs = task_pt_regs(task); | |
2eac7648 | 82 | unsigned long args[6]; |
e2cfabdf | 83 | |
bd4cf0ed | 84 | sd->nr = syscall_get_nr(task, regs); |
0b747172 | 85 | sd->arch = syscall_get_arch(); |
2eac7648 DB |
86 | syscall_get_arguments(task, regs, 0, 6, args); |
87 | sd->args[0] = args[0]; | |
88 | sd->args[1] = args[1]; | |
89 | sd->args[2] = args[2]; | |
90 | sd->args[3] = args[3]; | |
91 | sd->args[4] = args[4]; | |
92 | sd->args[5] = args[5]; | |
bd4cf0ed | 93 | sd->instruction_pointer = KSTK_EIP(task); |
e2cfabdf WD |
94 | } |
95 | ||
96 | /** | |
97 | * seccomp_check_filter - verify seccomp filter code | |
98 | * @filter: filter to verify | |
99 | * @flen: length of filter | |
100 | * | |
4df95ff4 | 101 | * Takes a previously checked filter (by bpf_check_classic) and |
e2cfabdf WD |
102 | * redirects all filter code that loads struct sk_buff data |
103 | * and related data through seccomp_bpf_load. It also | |
104 | * enforces length and alignment checking of those loads. | |
105 | * | |
106 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
107 | */ | |
108 | static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) | |
109 | { | |
110 | int pc; | |
111 | for (pc = 0; pc < flen; pc++) { | |
112 | struct sock_filter *ftest = &filter[pc]; | |
113 | u16 code = ftest->code; | |
114 | u32 k = ftest->k; | |
115 | ||
116 | switch (code) { | |
34805931 | 117 | case BPF_LD | BPF_W | BPF_ABS: |
bd4cf0ed | 118 | ftest->code = BPF_LDX | BPF_W | BPF_ABS; |
e2cfabdf WD |
119 | /* 32-bit aligned and not out of bounds. */ |
120 | if (k >= sizeof(struct seccomp_data) || k & 3) | |
121 | return -EINVAL; | |
122 | continue; | |
34805931 | 123 | case BPF_LD | BPF_W | BPF_LEN: |
bd4cf0ed | 124 | ftest->code = BPF_LD | BPF_IMM; |
e2cfabdf WD |
125 | ftest->k = sizeof(struct seccomp_data); |
126 | continue; | |
34805931 | 127 | case BPF_LDX | BPF_W | BPF_LEN: |
bd4cf0ed | 128 | ftest->code = BPF_LDX | BPF_IMM; |
e2cfabdf WD |
129 | ftest->k = sizeof(struct seccomp_data); |
130 | continue; | |
131 | /* Explicitly include allowed calls. */ | |
34805931 DB |
132 | case BPF_RET | BPF_K: |
133 | case BPF_RET | BPF_A: | |
134 | case BPF_ALU | BPF_ADD | BPF_K: | |
135 | case BPF_ALU | BPF_ADD | BPF_X: | |
136 | case BPF_ALU | BPF_SUB | BPF_K: | |
137 | case BPF_ALU | BPF_SUB | BPF_X: | |
138 | case BPF_ALU | BPF_MUL | BPF_K: | |
139 | case BPF_ALU | BPF_MUL | BPF_X: | |
140 | case BPF_ALU | BPF_DIV | BPF_K: | |
141 | case BPF_ALU | BPF_DIV | BPF_X: | |
142 | case BPF_ALU | BPF_AND | BPF_K: | |
143 | case BPF_ALU | BPF_AND | BPF_X: | |
144 | case BPF_ALU | BPF_OR | BPF_K: | |
145 | case BPF_ALU | BPF_OR | BPF_X: | |
146 | case BPF_ALU | BPF_XOR | BPF_K: | |
147 | case BPF_ALU | BPF_XOR | BPF_X: | |
148 | case BPF_ALU | BPF_LSH | BPF_K: | |
149 | case BPF_ALU | BPF_LSH | BPF_X: | |
150 | case BPF_ALU | BPF_RSH | BPF_K: | |
151 | case BPF_ALU | BPF_RSH | BPF_X: | |
152 | case BPF_ALU | BPF_NEG: | |
153 | case BPF_LD | BPF_IMM: | |
154 | case BPF_LDX | BPF_IMM: | |
155 | case BPF_MISC | BPF_TAX: | |
156 | case BPF_MISC | BPF_TXA: | |
157 | case BPF_LD | BPF_MEM: | |
158 | case BPF_LDX | BPF_MEM: | |
159 | case BPF_ST: | |
160 | case BPF_STX: | |
161 | case BPF_JMP | BPF_JA: | |
162 | case BPF_JMP | BPF_JEQ | BPF_K: | |
163 | case BPF_JMP | BPF_JEQ | BPF_X: | |
164 | case BPF_JMP | BPF_JGE | BPF_K: | |
165 | case BPF_JMP | BPF_JGE | BPF_X: | |
166 | case BPF_JMP | BPF_JGT | BPF_K: | |
167 | case BPF_JMP | BPF_JGT | BPF_X: | |
168 | case BPF_JMP | BPF_JSET | BPF_K: | |
169 | case BPF_JMP | BPF_JSET | BPF_X: | |
e2cfabdf WD |
170 | continue; |
171 | default: | |
172 | return -EINVAL; | |
173 | } | |
174 | } | |
175 | return 0; | |
176 | } | |
177 | ||
178 | /** | |
285fdfc5 MS |
179 | * seccomp_run_filters - evaluates all seccomp filters against @sd |
180 | * @sd: optional seccomp data to be passed to filters | |
deb4de8b KC |
181 | * @match: stores struct seccomp_filter that resulted in the return value, |
182 | * unless filter returned SECCOMP_RET_ALLOW, in which case it will | |
183 | * be unchanged. | |
e2cfabdf WD |
184 | * |
185 | * Returns valid seccomp BPF response codes. | |
186 | */ | |
0466bdb9 | 187 | #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL))) |
deb4de8b KC |
188 | static u32 seccomp_run_filters(const struct seccomp_data *sd, |
189 | struct seccomp_filter **match) | |
e2cfabdf | 190 | { |
d39bd00d | 191 | struct seccomp_data sd_local; |
acf3b2c7 | 192 | u32 ret = SECCOMP_RET_ALLOW; |
8225d385 PK |
193 | /* Make sure cross-thread synced filter points somewhere sane. */ |
194 | struct seccomp_filter *f = | |
506458ef | 195 | READ_ONCE(current->seccomp.filter); |
acf3b2c7 WD |
196 | |
197 | /* Ensure unexpected behavior doesn't result in failing open. */ | |
3ba2530c | 198 | if (unlikely(WARN_ON(f == NULL))) |
4d3b0b05 | 199 | return SECCOMP_RET_KILL_PROCESS; |
acf3b2c7 | 200 | |
d39bd00d AL |
201 | if (!sd) { |
202 | populate_seccomp_data(&sd_local); | |
203 | sd = &sd_local; | |
204 | } | |
bd4cf0ed | 205 | |
e2cfabdf WD |
206 | /* |
207 | * All filters in the list are evaluated and the lowest BPF return | |
acf3b2c7 | 208 | * value always takes priority (ignoring the DATA). |
e2cfabdf | 209 | */ |
3ba2530c | 210 | for (; f; f = f->prev) { |
88575199 | 211 | u32 cur_ret = BPF_PROG_RUN(f->prog, sd); |
8f577cad | 212 | |
0466bdb9 | 213 | if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) { |
acf3b2c7 | 214 | ret = cur_ret; |
deb4de8b KC |
215 | *match = f; |
216 | } | |
e2cfabdf WD |
217 | } |
218 | return ret; | |
219 | } | |
1f41b450 | 220 | #endif /* CONFIG_SECCOMP_FILTER */ |
e2cfabdf | 221 | |
1f41b450 KC |
222 | static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) |
223 | { | |
69f6a34b | 224 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 225 | |
1f41b450 KC |
226 | if (current->seccomp.mode && current->seccomp.mode != seccomp_mode) |
227 | return false; | |
228 | ||
229 | return true; | |
230 | } | |
231 | ||
8bf37d8c | 232 | void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { } |
5c307089 | 233 | |
3ba2530c | 234 | static inline void seccomp_assign_mode(struct task_struct *task, |
00a02d0c KC |
235 | unsigned long seccomp_mode, |
236 | unsigned long flags) | |
1f41b450 | 237 | { |
69f6a34b | 238 | assert_spin_locked(&task->sighand->siglock); |
dbd95212 | 239 | |
3ba2530c KC |
240 | task->seccomp.mode = seccomp_mode; |
241 | /* | |
242 | * Make sure TIF_SECCOMP cannot be set before the mode (and | |
243 | * filter) is set. | |
244 | */ | |
245 | smp_mb__before_atomic(); | |
00a02d0c KC |
246 | /* Assume default seccomp processes want spec flaw mitigation. */ |
247 | if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0) | |
8bf37d8c | 248 | arch_seccomp_spec_mitigate(task); |
3ba2530c | 249 | set_tsk_thread_flag(task, TIF_SECCOMP); |
1f41b450 KC |
250 | } |
251 | ||
252 | #ifdef CONFIG_SECCOMP_FILTER | |
c2e1f2e3 KC |
253 | /* Returns 1 if the parent is an ancestor of the child. */ |
254 | static int is_ancestor(struct seccomp_filter *parent, | |
255 | struct seccomp_filter *child) | |
256 | { | |
257 | /* NULL is the root ancestor. */ | |
258 | if (parent == NULL) | |
259 | return 1; | |
260 | for (; child; child = child->prev) | |
261 | if (child == parent) | |
262 | return 1; | |
263 | return 0; | |
264 | } | |
265 | ||
266 | /** | |
267 | * seccomp_can_sync_threads: checks if all threads can be synchronized | |
268 | * | |
269 | * Expects sighand and cred_guard_mutex locks to be held. | |
270 | * | |
271 | * Returns 0 on success, -ve on error, or the pid of a thread which was | |
272 | * either not in the correct seccomp mode or it did not have an ancestral | |
273 | * seccomp filter. | |
274 | */ | |
275 | static inline pid_t seccomp_can_sync_threads(void) | |
276 | { | |
277 | struct task_struct *thread, *caller; | |
278 | ||
279 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 280 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
281 | |
282 | /* Validate all threads being eligible for synchronization. */ | |
283 | caller = current; | |
284 | for_each_thread(caller, thread) { | |
285 | pid_t failed; | |
286 | ||
287 | /* Skip current, since it is initiating the sync. */ | |
288 | if (thread == caller) | |
289 | continue; | |
290 | ||
291 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || | |
292 | (thread->seccomp.mode == SECCOMP_MODE_FILTER && | |
293 | is_ancestor(thread->seccomp.filter, | |
294 | caller->seccomp.filter))) | |
295 | continue; | |
296 | ||
297 | /* Return the first thread that cannot be synchronized. */ | |
298 | failed = task_pid_vnr(thread); | |
299 | /* If the pid cannot be resolved, then return -ESRCH */ | |
300 | if (unlikely(WARN_ON(failed == 0))) | |
301 | failed = -ESRCH; | |
302 | return failed; | |
303 | } | |
304 | ||
305 | return 0; | |
306 | } | |
307 | ||
308 | /** | |
309 | * seccomp_sync_threads: sets all threads to use current's filter | |
310 | * | |
311 | * Expects sighand and cred_guard_mutex locks to be held, and for | |
312 | * seccomp_can_sync_threads() to have returned success already | |
313 | * without dropping the locks. | |
314 | * | |
315 | */ | |
00a02d0c | 316 | static inline void seccomp_sync_threads(unsigned long flags) |
c2e1f2e3 KC |
317 | { |
318 | struct task_struct *thread, *caller; | |
319 | ||
320 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 321 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
322 | |
323 | /* Synchronize all threads. */ | |
324 | caller = current; | |
325 | for_each_thread(caller, thread) { | |
326 | /* Skip current, since it needs no changes. */ | |
327 | if (thread == caller) | |
328 | continue; | |
329 | ||
330 | /* Get a task reference for the new leaf node. */ | |
331 | get_seccomp_filter(caller); | |
332 | /* | |
333 | * Drop the task reference to the shared ancestor since | |
334 | * current's path will hold a reference. (This also | |
335 | * allows a put before the assignment.) | |
336 | */ | |
337 | put_seccomp_filter(thread); | |
338 | smp_store_release(&thread->seccomp.filter, | |
339 | caller->seccomp.filter); | |
103502a3 JH |
340 | |
341 | /* | |
342 | * Don't let an unprivileged task work around | |
343 | * the no_new_privs restriction by creating | |
344 | * a thread that sets it up, enters seccomp, | |
345 | * then dies. | |
346 | */ | |
347 | if (task_no_new_privs(caller)) | |
348 | task_set_no_new_privs(thread); | |
349 | ||
c2e1f2e3 KC |
350 | /* |
351 | * Opt the other thread into seccomp if needed. | |
352 | * As threads are considered to be trust-realm | |
353 | * equivalent (see ptrace_may_access), it is safe to | |
354 | * allow one thread to transition the other. | |
355 | */ | |
103502a3 | 356 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) |
00a02d0c KC |
357 | seccomp_assign_mode(thread, SECCOMP_MODE_FILTER, |
358 | flags); | |
c2e1f2e3 KC |
359 | } |
360 | } | |
361 | ||
e2cfabdf | 362 | /** |
c8bee430 | 363 | * seccomp_prepare_filter: Prepares a seccomp filter for use. |
e2cfabdf WD |
364 | * @fprog: BPF program to install |
365 | * | |
c8bee430 | 366 | * Returns filter on success or an ERR_PTR on failure. |
e2cfabdf | 367 | */ |
c8bee430 | 368 | static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) |
e2cfabdf | 369 | { |
ac67eb2c DB |
370 | struct seccomp_filter *sfilter; |
371 | int ret; | |
97f2645f | 372 | const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE); |
e2cfabdf WD |
373 | |
374 | if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) | |
c8bee430 | 375 | return ERR_PTR(-EINVAL); |
d9e12f42 | 376 | |
c8bee430 | 377 | BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); |
e2cfabdf WD |
378 | |
379 | /* | |
119ce5c8 | 380 | * Installing a seccomp filter requires that the task has |
e2cfabdf WD |
381 | * CAP_SYS_ADMIN in its namespace or be running with no_new_privs. |
382 | * This avoids scenarios where unprivileged tasks can affect the | |
383 | * behavior of privileged children. | |
384 | */ | |
1d4457f9 | 385 | if (!task_no_new_privs(current) && |
e2cfabdf WD |
386 | security_capable_noaudit(current_cred(), current_user_ns(), |
387 | CAP_SYS_ADMIN) != 0) | |
c8bee430 | 388 | return ERR_PTR(-EACCES); |
e2cfabdf | 389 | |
bd4cf0ed | 390 | /* Allocate a new seccomp_filter */ |
ac67eb2c DB |
391 | sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN); |
392 | if (!sfilter) | |
d9e12f42 | 393 | return ERR_PTR(-ENOMEM); |
ac67eb2c DB |
394 | |
395 | ret = bpf_prog_create_from_user(&sfilter->prog, fprog, | |
f8e529ed | 396 | seccomp_check_filter, save_orig); |
ac67eb2c DB |
397 | if (ret < 0) { |
398 | kfree(sfilter); | |
399 | return ERR_PTR(ret); | |
d9e12f42 | 400 | } |
bd4cf0ed | 401 | |
0b5fa229 | 402 | refcount_set(&sfilter->usage, 1); |
e2cfabdf | 403 | |
ac67eb2c | 404 | return sfilter; |
e2cfabdf WD |
405 | } |
406 | ||
407 | /** | |
c8bee430 | 408 | * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog |
e2cfabdf WD |
409 | * @user_filter: pointer to the user data containing a sock_fprog. |
410 | * | |
411 | * Returns 0 on success and non-zero otherwise. | |
412 | */ | |
c8bee430 KC |
413 | static struct seccomp_filter * |
414 | seccomp_prepare_user_filter(const char __user *user_filter) | |
e2cfabdf WD |
415 | { |
416 | struct sock_fprog fprog; | |
c8bee430 | 417 | struct seccomp_filter *filter = ERR_PTR(-EFAULT); |
e2cfabdf WD |
418 | |
419 | #ifdef CONFIG_COMPAT | |
5c38065e | 420 | if (in_compat_syscall()) { |
e2cfabdf WD |
421 | struct compat_sock_fprog fprog32; |
422 | if (copy_from_user(&fprog32, user_filter, sizeof(fprog32))) | |
423 | goto out; | |
424 | fprog.len = fprog32.len; | |
425 | fprog.filter = compat_ptr(fprog32.filter); | |
426 | } else /* falls through to the if below. */ | |
427 | #endif | |
428 | if (copy_from_user(&fprog, user_filter, sizeof(fprog))) | |
429 | goto out; | |
c8bee430 | 430 | filter = seccomp_prepare_filter(&fprog); |
e2cfabdf | 431 | out: |
c8bee430 KC |
432 | return filter; |
433 | } | |
434 | ||
435 | /** | |
436 | * seccomp_attach_filter: validate and attach filter | |
437 | * @flags: flags to change filter behavior | |
438 | * @filter: seccomp filter to add to the current process | |
439 | * | |
dbd95212 KC |
440 | * Caller must be holding current->sighand->siglock lock. |
441 | * | |
c8bee430 KC |
442 | * Returns 0 on success, -ve on error. |
443 | */ | |
444 | static long seccomp_attach_filter(unsigned int flags, | |
445 | struct seccomp_filter *filter) | |
446 | { | |
447 | unsigned long total_insns; | |
448 | struct seccomp_filter *walker; | |
449 | ||
69f6a34b | 450 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 451 | |
c8bee430 KC |
452 | /* Validate resulting filter length. */ |
453 | total_insns = filter->prog->len; | |
454 | for (walker = current->seccomp.filter; walker; walker = walker->prev) | |
455 | total_insns += walker->prog->len + 4; /* 4 instr penalty */ | |
456 | if (total_insns > MAX_INSNS_PER_PATH) | |
457 | return -ENOMEM; | |
458 | ||
c2e1f2e3 KC |
459 | /* If thread sync has been requested, check that it is possible. */ |
460 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) { | |
461 | int ret; | |
462 | ||
463 | ret = seccomp_can_sync_threads(); | |
464 | if (ret) | |
465 | return ret; | |
466 | } | |
467 | ||
e66a3997 TH |
468 | /* Set log flag, if present. */ |
469 | if (flags & SECCOMP_FILTER_FLAG_LOG) | |
470 | filter->log = true; | |
471 | ||
c8bee430 KC |
472 | /* |
473 | * If there is an existing filter, make it the prev and don't drop its | |
474 | * task reference. | |
475 | */ | |
476 | filter->prev = current->seccomp.filter; | |
477 | current->seccomp.filter = filter; | |
478 | ||
c2e1f2e3 KC |
479 | /* Now that the new filter is in place, synchronize to all threads. */ |
480 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) | |
00a02d0c | 481 | seccomp_sync_threads(flags); |
c2e1f2e3 | 482 | |
c8bee430 | 483 | return 0; |
e2cfabdf WD |
484 | } |
485 | ||
084f5601 | 486 | static void __get_seccomp_filter(struct seccomp_filter *filter) |
66a733ea ON |
487 | { |
488 | /* Reference count is bounded by the number of total processes. */ | |
489 | refcount_inc(&filter->usage); | |
490 | } | |
491 | ||
e2cfabdf WD |
492 | /* get_seccomp_filter - increments the reference count of the filter on @tsk */ |
493 | void get_seccomp_filter(struct task_struct *tsk) | |
494 | { | |
495 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
496 | if (!orig) | |
497 | return; | |
66a733ea | 498 | __get_seccomp_filter(orig); |
e2cfabdf WD |
499 | } |
500 | ||
c8bee430 KC |
501 | static inline void seccomp_filter_free(struct seccomp_filter *filter) |
502 | { | |
503 | if (filter) { | |
bab18991 | 504 | bpf_prog_destroy(filter->prog); |
c8bee430 KC |
505 | kfree(filter); |
506 | } | |
507 | } | |
508 | ||
66a733ea | 509 | static void __put_seccomp_filter(struct seccomp_filter *orig) |
e2cfabdf | 510 | { |
e2cfabdf | 511 | /* Clean up single-reference branches iteratively. */ |
0b5fa229 | 512 | while (orig && refcount_dec_and_test(&orig->usage)) { |
e2cfabdf WD |
513 | struct seccomp_filter *freeme = orig; |
514 | orig = orig->prev; | |
c8bee430 | 515 | seccomp_filter_free(freeme); |
e2cfabdf WD |
516 | } |
517 | } | |
bb6ea430 | 518 | |
66a733ea ON |
519 | /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */ |
520 | void put_seccomp_filter(struct task_struct *tsk) | |
521 | { | |
522 | __put_seccomp_filter(tsk->seccomp.filter); | |
523 | } | |
524 | ||
b25e6716 MF |
525 | static void seccomp_init_siginfo(siginfo_t *info, int syscall, int reason) |
526 | { | |
3b10db2b | 527 | clear_siginfo(info); |
b25e6716 MF |
528 | info->si_signo = SIGSYS; |
529 | info->si_code = SYS_SECCOMP; | |
530 | info->si_call_addr = (void __user *)KSTK_EIP(current); | |
531 | info->si_errno = reason; | |
532 | info->si_arch = syscall_get_arch(); | |
533 | info->si_syscall = syscall; | |
534 | } | |
535 | ||
bb6ea430 WD |
536 | /** |
537 | * seccomp_send_sigsys - signals the task to allow in-process syscall emulation | |
538 | * @syscall: syscall number to send to userland | |
539 | * @reason: filter-supplied reason code to send to userland (via si_errno) | |
540 | * | |
541 | * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. | |
542 | */ | |
543 | static void seccomp_send_sigsys(int syscall, int reason) | |
544 | { | |
545 | struct siginfo info; | |
b25e6716 | 546 | seccomp_init_siginfo(&info, syscall, reason); |
bb6ea430 WD |
547 | force_sig_info(SIGSYS, &info, current); |
548 | } | |
e2cfabdf | 549 | #endif /* CONFIG_SECCOMP_FILTER */ |
1da177e4 | 550 | |
0ddec0fc | 551 | /* For use with seccomp_actions_logged */ |
4d3b0b05 KC |
552 | #define SECCOMP_LOG_KILL_PROCESS (1 << 0) |
553 | #define SECCOMP_LOG_KILL_THREAD (1 << 1) | |
0ddec0fc TH |
554 | #define SECCOMP_LOG_TRAP (1 << 2) |
555 | #define SECCOMP_LOG_ERRNO (1 << 3) | |
556 | #define SECCOMP_LOG_TRACE (1 << 4) | |
59f5cf44 TH |
557 | #define SECCOMP_LOG_LOG (1 << 5) |
558 | #define SECCOMP_LOG_ALLOW (1 << 6) | |
0ddec0fc | 559 | |
4d3b0b05 KC |
560 | static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS | |
561 | SECCOMP_LOG_KILL_THREAD | | |
fd76875c KC |
562 | SECCOMP_LOG_TRAP | |
563 | SECCOMP_LOG_ERRNO | | |
564 | SECCOMP_LOG_TRACE | | |
59f5cf44 | 565 | SECCOMP_LOG_LOG; |
0ddec0fc | 566 | |
e66a3997 TH |
567 | static inline void seccomp_log(unsigned long syscall, long signr, u32 action, |
568 | bool requested) | |
0ddec0fc TH |
569 | { |
570 | bool log = false; | |
571 | ||
572 | switch (action) { | |
573 | case SECCOMP_RET_ALLOW: | |
e66a3997 | 574 | break; |
0ddec0fc | 575 | case SECCOMP_RET_TRAP: |
e66a3997 TH |
576 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP; |
577 | break; | |
0ddec0fc | 578 | case SECCOMP_RET_ERRNO: |
e66a3997 TH |
579 | log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO; |
580 | break; | |
0ddec0fc | 581 | case SECCOMP_RET_TRACE: |
e66a3997 | 582 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE; |
0ddec0fc | 583 | break; |
59f5cf44 TH |
584 | case SECCOMP_RET_LOG: |
585 | log = seccomp_actions_logged & SECCOMP_LOG_LOG; | |
586 | break; | |
fd76875c | 587 | case SECCOMP_RET_KILL_THREAD: |
fd76875c | 588 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD; |
4d3b0b05 KC |
589 | break; |
590 | case SECCOMP_RET_KILL_PROCESS: | |
591 | default: | |
592 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS; | |
0ddec0fc TH |
593 | } |
594 | ||
595 | /* | |
326bee02 TH |
596 | * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the |
597 | * FILTER_FLAG_LOG bit was set. The admin has the ability to silence | |
598 | * any action from being logged by removing the action name from the | |
599 | * seccomp_actions_logged sysctl. | |
0ddec0fc | 600 | */ |
326bee02 TH |
601 | if (!log) |
602 | return; | |
0ddec0fc | 603 | |
326bee02 | 604 | audit_seccomp(syscall, signr, action); |
0ddec0fc TH |
605 | } |
606 | ||
1da177e4 LT |
607 | /* |
608 | * Secure computing mode 1 allows only read/write/exit/sigreturn. | |
609 | * To be fully secure this must be combined with rlimit | |
610 | * to limit the stack allocations too. | |
611 | */ | |
cb4253aa | 612 | static const int mode1_syscalls[] = { |
1da177e4 LT |
613 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, |
614 | 0, /* null terminated */ | |
615 | }; | |
616 | ||
a4412fc9 | 617 | static void __secure_computing_strict(int this_syscall) |
1da177e4 | 618 | { |
cb4253aa | 619 | const int *syscall_whitelist = mode1_syscalls; |
a4412fc9 | 620 | #ifdef CONFIG_COMPAT |
5c38065e | 621 | if (in_compat_syscall()) |
c983f0e8 | 622 | syscall_whitelist = get_compat_mode1_syscalls(); |
a4412fc9 AL |
623 | #endif |
624 | do { | |
625 | if (*syscall_whitelist == this_syscall) | |
626 | return; | |
627 | } while (*++syscall_whitelist); | |
628 | ||
629 | #ifdef SECCOMP_DEBUG | |
630 | dump_stack(); | |
631 | #endif | |
fd76875c | 632 | seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true); |
a4412fc9 AL |
633 | do_exit(SIGKILL); |
634 | } | |
635 | ||
636 | #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER | |
637 | void secure_computing_strict(int this_syscall) | |
638 | { | |
639 | int mode = current->seccomp.mode; | |
640 | ||
97f2645f | 641 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 TA |
642 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
643 | return; | |
644 | ||
221272f9 | 645 | if (mode == SECCOMP_MODE_DISABLED) |
a4412fc9 AL |
646 | return; |
647 | else if (mode == SECCOMP_MODE_STRICT) | |
648 | __secure_computing_strict(this_syscall); | |
649 | else | |
650 | BUG(); | |
651 | } | |
652 | #else | |
13aa72f0 AL |
653 | |
654 | #ifdef CONFIG_SECCOMP_FILTER | |
ce6526e8 KC |
655 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
656 | const bool recheck_after_trace) | |
13aa72f0 AL |
657 | { |
658 | u32 filter_ret, action; | |
deb4de8b | 659 | struct seccomp_filter *match = NULL; |
13aa72f0 | 660 | int data; |
1da177e4 | 661 | |
3ba2530c KC |
662 | /* |
663 | * Make sure that any changes to mode from another thread have | |
664 | * been seen after TIF_SECCOMP was seen. | |
665 | */ | |
666 | rmb(); | |
667 | ||
deb4de8b | 668 | filter_ret = seccomp_run_filters(sd, &match); |
13aa72f0 | 669 | data = filter_ret & SECCOMP_RET_DATA; |
0466bdb9 | 670 | action = filter_ret & SECCOMP_RET_ACTION_FULL; |
13aa72f0 AL |
671 | |
672 | switch (action) { | |
673 | case SECCOMP_RET_ERRNO: | |
580c57f1 KC |
674 | /* Set low-order bits as an errno, capped at MAX_ERRNO. */ |
675 | if (data > MAX_ERRNO) | |
676 | data = MAX_ERRNO; | |
d39bd00d | 677 | syscall_set_return_value(current, task_pt_regs(current), |
13aa72f0 AL |
678 | -data, 0); |
679 | goto skip; | |
680 | ||
681 | case SECCOMP_RET_TRAP: | |
682 | /* Show the handler the original registers. */ | |
d39bd00d | 683 | syscall_rollback(current, task_pt_regs(current)); |
13aa72f0 AL |
684 | /* Let the filter pass back 16 bits of data. */ |
685 | seccomp_send_sigsys(this_syscall, data); | |
686 | goto skip; | |
687 | ||
688 | case SECCOMP_RET_TRACE: | |
ce6526e8 KC |
689 | /* We've been put in this state by the ptracer already. */ |
690 | if (recheck_after_trace) | |
691 | return 0; | |
692 | ||
8112c4f1 KC |
693 | /* ENOSYS these calls if there is no tracer attached. */ |
694 | if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { | |
695 | syscall_set_return_value(current, | |
696 | task_pt_regs(current), | |
697 | -ENOSYS, 0); | |
698 | goto skip; | |
699 | } | |
700 | ||
701 | /* Allow the BPF to provide the event message */ | |
702 | ptrace_event(PTRACE_EVENT_SECCOMP, data); | |
703 | /* | |
704 | * The delivery of a fatal signal during event | |
485a252a KC |
705 | * notification may silently skip tracer notification, |
706 | * which could leave us with a potentially unmodified | |
707 | * syscall that the tracer would have liked to have | |
708 | * changed. Since the process is about to die, we just | |
709 | * force the syscall to be skipped and let the signal | |
710 | * kill the process and correctly handle any tracer exit | |
711 | * notifications. | |
8112c4f1 KC |
712 | */ |
713 | if (fatal_signal_pending(current)) | |
485a252a | 714 | goto skip; |
8112c4f1 KC |
715 | /* Check if the tracer forced the syscall to be skipped. */ |
716 | this_syscall = syscall_get_nr(current, task_pt_regs(current)); | |
717 | if (this_syscall < 0) | |
718 | goto skip; | |
719 | ||
ce6526e8 KC |
720 | /* |
721 | * Recheck the syscall, since it may have changed. This | |
722 | * intentionally uses a NULL struct seccomp_data to force | |
723 | * a reload of all registers. This does not goto skip since | |
724 | * a skip would have already been reported. | |
725 | */ | |
726 | if (__seccomp_filter(this_syscall, NULL, true)) | |
727 | return -1; | |
728 | ||
8112c4f1 | 729 | return 0; |
13aa72f0 | 730 | |
59f5cf44 TH |
731 | case SECCOMP_RET_LOG: |
732 | seccomp_log(this_syscall, 0, action, true); | |
733 | return 0; | |
734 | ||
13aa72f0 | 735 | case SECCOMP_RET_ALLOW: |
deb4de8b KC |
736 | /* |
737 | * Note that the "match" filter will always be NULL for | |
738 | * this action since SECCOMP_RET_ALLOW is the starting | |
739 | * state in seccomp_run_filters(). | |
740 | */ | |
8112c4f1 | 741 | return 0; |
13aa72f0 | 742 | |
fd76875c | 743 | case SECCOMP_RET_KILL_THREAD: |
4d3b0b05 | 744 | case SECCOMP_RET_KILL_PROCESS: |
131b6351 | 745 | default: |
e66a3997 | 746 | seccomp_log(this_syscall, SIGSYS, action, true); |
d7276e32 | 747 | /* Dump core only if this is the last remaining thread. */ |
4d3b0b05 KC |
748 | if (action == SECCOMP_RET_KILL_PROCESS || |
749 | get_nr_threads(current) == 1) { | |
131b6351 KC |
750 | siginfo_t info; |
751 | ||
d7276e32 KC |
752 | /* Show the original registers in the dump. */ |
753 | syscall_rollback(current, task_pt_regs(current)); | |
754 | /* Trigger a manual coredump since do_exit skips it. */ | |
755 | seccomp_init_siginfo(&info, this_syscall, data); | |
756 | do_coredump(&info); | |
757 | } | |
4d3b0b05 KC |
758 | if (action == SECCOMP_RET_KILL_PROCESS) |
759 | do_group_exit(SIGSYS); | |
760 | else | |
761 | do_exit(SIGSYS); | |
13aa72f0 AL |
762 | } |
763 | ||
764 | unreachable(); | |
765 | ||
766 | skip: | |
e66a3997 | 767 | seccomp_log(this_syscall, 0, action, match ? match->log : false); |
8112c4f1 KC |
768 | return -1; |
769 | } | |
770 | #else | |
ce6526e8 KC |
771 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
772 | const bool recheck_after_trace) | |
8112c4f1 KC |
773 | { |
774 | BUG(); | |
13aa72f0 | 775 | } |
1da177e4 | 776 | #endif |
13aa72f0 | 777 | |
8112c4f1 | 778 | int __secure_computing(const struct seccomp_data *sd) |
13aa72f0 AL |
779 | { |
780 | int mode = current->seccomp.mode; | |
8112c4f1 | 781 | int this_syscall; |
13aa72f0 | 782 | |
97f2645f | 783 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 | 784 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
8112c4f1 KC |
785 | return 0; |
786 | ||
787 | this_syscall = sd ? sd->nr : | |
788 | syscall_get_nr(current, task_pt_regs(current)); | |
13c4a901 | 789 | |
13aa72f0 | 790 | switch (mode) { |
e2cfabdf | 791 | case SECCOMP_MODE_STRICT: |
13aa72f0 | 792 | __secure_computing_strict(this_syscall); /* may call do_exit */ |
8112c4f1 | 793 | return 0; |
13aa72f0 | 794 | case SECCOMP_MODE_FILTER: |
ce6526e8 | 795 | return __seccomp_filter(this_syscall, sd, false); |
1da177e4 LT |
796 | default: |
797 | BUG(); | |
798 | } | |
13aa72f0 | 799 | } |
a4412fc9 | 800 | #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */ |
1d9d02fe AA |
801 | |
802 | long prctl_get_seccomp(void) | |
803 | { | |
804 | return current->seccomp.mode; | |
805 | } | |
806 | ||
e2cfabdf | 807 | /** |
3b23dd12 | 808 | * seccomp_set_mode_strict: internal function for setting strict seccomp |
e2cfabdf WD |
809 | * |
810 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
811 | * | |
812 | * Returns 0 on success or -EINVAL on failure. | |
813 | */ | |
3b23dd12 | 814 | static long seccomp_set_mode_strict(void) |
1d9d02fe | 815 | { |
3b23dd12 | 816 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT; |
e2cfabdf | 817 | long ret = -EINVAL; |
1d9d02fe | 818 | |
dbd95212 KC |
819 | spin_lock_irq(¤t->sighand->siglock); |
820 | ||
1f41b450 | 821 | if (!seccomp_may_assign_mode(seccomp_mode)) |
1d9d02fe AA |
822 | goto out; |
823 | ||
cf99abac | 824 | #ifdef TIF_NOTSC |
3b23dd12 | 825 | disable_TSC(); |
cf99abac | 826 | #endif |
00a02d0c | 827 | seccomp_assign_mode(current, seccomp_mode, 0); |
3b23dd12 KC |
828 | ret = 0; |
829 | ||
830 | out: | |
dbd95212 | 831 | spin_unlock_irq(¤t->sighand->siglock); |
3b23dd12 KC |
832 | |
833 | return ret; | |
834 | } | |
835 | ||
e2cfabdf | 836 | #ifdef CONFIG_SECCOMP_FILTER |
3b23dd12 KC |
837 | /** |
838 | * seccomp_set_mode_filter: internal function for setting seccomp filter | |
48dc92b9 | 839 | * @flags: flags to change filter behavior |
3b23dd12 KC |
840 | * @filter: struct sock_fprog containing filter |
841 | * | |
842 | * This function may be called repeatedly to install additional filters. | |
843 | * Every filter successfully installed will be evaluated (in reverse order) | |
844 | * for each system call the task makes. | |
845 | * | |
846 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
847 | * | |
848 | * Returns 0 on success or -EINVAL on failure. | |
849 | */ | |
48dc92b9 KC |
850 | static long seccomp_set_mode_filter(unsigned int flags, |
851 | const char __user *filter) | |
3b23dd12 KC |
852 | { |
853 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; | |
c8bee430 | 854 | struct seccomp_filter *prepared = NULL; |
3b23dd12 KC |
855 | long ret = -EINVAL; |
856 | ||
48dc92b9 | 857 | /* Validate flags. */ |
c2e1f2e3 | 858 | if (flags & ~SECCOMP_FILTER_FLAG_MASK) |
dbd95212 | 859 | return -EINVAL; |
48dc92b9 | 860 | |
c8bee430 KC |
861 | /* Prepare the new filter before holding any locks. */ |
862 | prepared = seccomp_prepare_user_filter(filter); | |
863 | if (IS_ERR(prepared)) | |
864 | return PTR_ERR(prepared); | |
865 | ||
c2e1f2e3 KC |
866 | /* |
867 | * Make sure we cannot change seccomp or nnp state via TSYNC | |
868 | * while another thread is in the middle of calling exec. | |
869 | */ | |
870 | if (flags & SECCOMP_FILTER_FLAG_TSYNC && | |
871 | mutex_lock_killable(¤t->signal->cred_guard_mutex)) | |
872 | goto out_free; | |
873 | ||
dbd95212 KC |
874 | spin_lock_irq(¤t->sighand->siglock); |
875 | ||
3b23dd12 KC |
876 | if (!seccomp_may_assign_mode(seccomp_mode)) |
877 | goto out; | |
878 | ||
c8bee430 | 879 | ret = seccomp_attach_filter(flags, prepared); |
3b23dd12 | 880 | if (ret) |
e2cfabdf | 881 | goto out; |
c8bee430 KC |
882 | /* Do not free the successfully attached filter. */ |
883 | prepared = NULL; | |
1d9d02fe | 884 | |
00a02d0c | 885 | seccomp_assign_mode(current, seccomp_mode, flags); |
e2cfabdf | 886 | out: |
dbd95212 | 887 | spin_unlock_irq(¤t->sighand->siglock); |
c2e1f2e3 KC |
888 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) |
889 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
890 | out_free: | |
c8bee430 | 891 | seccomp_filter_free(prepared); |
1d9d02fe AA |
892 | return ret; |
893 | } | |
3b23dd12 | 894 | #else |
48dc92b9 KC |
895 | static inline long seccomp_set_mode_filter(unsigned int flags, |
896 | const char __user *filter) | |
3b23dd12 KC |
897 | { |
898 | return -EINVAL; | |
899 | } | |
900 | #endif | |
d78ab02c | 901 | |
d612b1fd TH |
902 | static long seccomp_get_action_avail(const char __user *uaction) |
903 | { | |
904 | u32 action; | |
905 | ||
906 | if (copy_from_user(&action, uaction, sizeof(action))) | |
907 | return -EFAULT; | |
908 | ||
909 | switch (action) { | |
0466bdb9 | 910 | case SECCOMP_RET_KILL_PROCESS: |
fd76875c | 911 | case SECCOMP_RET_KILL_THREAD: |
d612b1fd TH |
912 | case SECCOMP_RET_TRAP: |
913 | case SECCOMP_RET_ERRNO: | |
914 | case SECCOMP_RET_TRACE: | |
59f5cf44 | 915 | case SECCOMP_RET_LOG: |
d612b1fd TH |
916 | case SECCOMP_RET_ALLOW: |
917 | break; | |
918 | default: | |
919 | return -EOPNOTSUPP; | |
920 | } | |
921 | ||
922 | return 0; | |
923 | } | |
924 | ||
48dc92b9 KC |
925 | /* Common entry point for both prctl and syscall. */ |
926 | static long do_seccomp(unsigned int op, unsigned int flags, | |
927 | const char __user *uargs) | |
928 | { | |
929 | switch (op) { | |
930 | case SECCOMP_SET_MODE_STRICT: | |
931 | if (flags != 0 || uargs != NULL) | |
932 | return -EINVAL; | |
933 | return seccomp_set_mode_strict(); | |
934 | case SECCOMP_SET_MODE_FILTER: | |
935 | return seccomp_set_mode_filter(flags, uargs); | |
d612b1fd TH |
936 | case SECCOMP_GET_ACTION_AVAIL: |
937 | if (flags != 0) | |
938 | return -EINVAL; | |
939 | ||
940 | return seccomp_get_action_avail(uargs); | |
48dc92b9 KC |
941 | default: |
942 | return -EINVAL; | |
943 | } | |
944 | } | |
945 | ||
946 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, | |
947 | const char __user *, uargs) | |
948 | { | |
949 | return do_seccomp(op, flags, uargs); | |
950 | } | |
951 | ||
d78ab02c KC |
952 | /** |
953 | * prctl_set_seccomp: configures current->seccomp.mode | |
954 | * @seccomp_mode: requested mode to use | |
955 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER | |
956 | * | |
957 | * Returns 0 on success or -EINVAL on failure. | |
958 | */ | |
959 | long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) | |
960 | { | |
48dc92b9 KC |
961 | unsigned int op; |
962 | char __user *uargs; | |
963 | ||
3b23dd12 KC |
964 | switch (seccomp_mode) { |
965 | case SECCOMP_MODE_STRICT: | |
48dc92b9 KC |
966 | op = SECCOMP_SET_MODE_STRICT; |
967 | /* | |
968 | * Setting strict mode through prctl always ignored filter, | |
969 | * so make sure it is always NULL here to pass the internal | |
970 | * check in do_seccomp(). | |
971 | */ | |
972 | uargs = NULL; | |
973 | break; | |
3b23dd12 | 974 | case SECCOMP_MODE_FILTER: |
48dc92b9 KC |
975 | op = SECCOMP_SET_MODE_FILTER; |
976 | uargs = filter; | |
977 | break; | |
3b23dd12 KC |
978 | default: |
979 | return -EINVAL; | |
980 | } | |
48dc92b9 KC |
981 | |
982 | /* prctl interface doesn't have flags, so they are always zero. */ | |
983 | return do_seccomp(op, 0, uargs); | |
d78ab02c | 984 | } |
f8e529ed TA |
985 | |
986 | #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) | |
f06eae83 TA |
987 | static struct seccomp_filter *get_nth_filter(struct task_struct *task, |
988 | unsigned long filter_off) | |
f8e529ed | 989 | { |
f06eae83 TA |
990 | struct seccomp_filter *orig, *filter; |
991 | unsigned long count; | |
f8e529ed | 992 | |
f06eae83 TA |
993 | /* |
994 | * Note: this is only correct because the caller should be the (ptrace) | |
995 | * tracer of the task, otherwise lock_task_sighand is needed. | |
996 | */ | |
f8e529ed | 997 | spin_lock_irq(&task->sighand->siglock); |
f06eae83 | 998 | |
f8e529ed | 999 | if (task->seccomp.mode != SECCOMP_MODE_FILTER) { |
f06eae83 TA |
1000 | spin_unlock_irq(&task->sighand->siglock); |
1001 | return ERR_PTR(-EINVAL); | |
f8e529ed TA |
1002 | } |
1003 | ||
f06eae83 TA |
1004 | orig = task->seccomp.filter; |
1005 | __get_seccomp_filter(orig); | |
1006 | spin_unlock_irq(&task->sighand->siglock); | |
1007 | ||
1008 | count = 0; | |
1009 | for (filter = orig; filter; filter = filter->prev) | |
f8e529ed | 1010 | count++; |
f8e529ed TA |
1011 | |
1012 | if (filter_off >= count) { | |
f06eae83 | 1013 | filter = ERR_PTR(-ENOENT); |
f8e529ed TA |
1014 | goto out; |
1015 | } | |
f8e529ed | 1016 | |
f06eae83 TA |
1017 | count -= filter_off; |
1018 | for (filter = orig; filter && count > 1; filter = filter->prev) | |
f8e529ed | 1019 | count--; |
f8e529ed TA |
1020 | |
1021 | if (WARN_ON(count != 1 || !filter)) { | |
f06eae83 | 1022 | filter = ERR_PTR(-ENOENT); |
f8e529ed TA |
1023 | goto out; |
1024 | } | |
1025 | ||
f06eae83 TA |
1026 | __get_seccomp_filter(filter); |
1027 | ||
1028 | out: | |
1029 | __put_seccomp_filter(orig); | |
1030 | return filter; | |
1031 | } | |
1032 | ||
1033 | long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, | |
1034 | void __user *data) | |
1035 | { | |
1036 | struct seccomp_filter *filter; | |
1037 | struct sock_fprog_kern *fprog; | |
1038 | long ret; | |
1039 | ||
1040 | if (!capable(CAP_SYS_ADMIN) || | |
1041 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { | |
1042 | return -EACCES; | |
1043 | } | |
1044 | ||
1045 | filter = get_nth_filter(task, filter_off); | |
1046 | if (IS_ERR(filter)) | |
1047 | return PTR_ERR(filter); | |
1048 | ||
f8e529ed TA |
1049 | fprog = filter->prog->orig_prog; |
1050 | if (!fprog) { | |
470bf1f2 | 1051 | /* This must be a new non-cBPF filter, since we save |
f8e529ed TA |
1052 | * every cBPF filter's orig_prog above when |
1053 | * CONFIG_CHECKPOINT_RESTORE is enabled. | |
1054 | */ | |
1055 | ret = -EMEDIUMTYPE; | |
1056 | goto out; | |
1057 | } | |
1058 | ||
1059 | ret = fprog->len; | |
1060 | if (!data) | |
1061 | goto out; | |
1062 | ||
f8e529ed TA |
1063 | if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog))) |
1064 | ret = -EFAULT; | |
1065 | ||
f8e529ed | 1066 | out: |
66a733ea | 1067 | __put_seccomp_filter(filter); |
f8e529ed | 1068 | return ret; |
f8e529ed | 1069 | } |
f8e529ed | 1070 | |
26500475 TA |
1071 | long seccomp_get_metadata(struct task_struct *task, |
1072 | unsigned long size, void __user *data) | |
1073 | { | |
1074 | long ret; | |
1075 | struct seccomp_filter *filter; | |
1076 | struct seccomp_metadata kmd = {}; | |
1077 | ||
1078 | if (!capable(CAP_SYS_ADMIN) || | |
1079 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { | |
1080 | return -EACCES; | |
1081 | } | |
1082 | ||
1083 | size = min_t(unsigned long, size, sizeof(kmd)); | |
1084 | ||
63bb0045 TA |
1085 | if (size < sizeof(kmd.filter_off)) |
1086 | return -EINVAL; | |
1087 | ||
1088 | if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off))) | |
26500475 TA |
1089 | return -EFAULT; |
1090 | ||
1091 | filter = get_nth_filter(task, kmd.filter_off); | |
1092 | if (IS_ERR(filter)) | |
1093 | return PTR_ERR(filter); | |
1094 | ||
26500475 TA |
1095 | if (filter->log) |
1096 | kmd.flags |= SECCOMP_FILTER_FLAG_LOG; | |
1097 | ||
1098 | ret = size; | |
1099 | if (copy_to_user(data, &kmd, size)) | |
1100 | ret = -EFAULT; | |
1101 | ||
1102 | __put_seccomp_filter(filter); | |
f8e529ed TA |
1103 | return ret; |
1104 | } | |
1105 | #endif | |
8e5f1ad1 TH |
1106 | |
1107 | #ifdef CONFIG_SYSCTL | |
1108 | ||
1109 | /* Human readable action names for friendly sysctl interaction */ | |
0466bdb9 | 1110 | #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process" |
fd76875c | 1111 | #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread" |
8e5f1ad1 TH |
1112 | #define SECCOMP_RET_TRAP_NAME "trap" |
1113 | #define SECCOMP_RET_ERRNO_NAME "errno" | |
1114 | #define SECCOMP_RET_TRACE_NAME "trace" | |
59f5cf44 | 1115 | #define SECCOMP_RET_LOG_NAME "log" |
8e5f1ad1 TH |
1116 | #define SECCOMP_RET_ALLOW_NAME "allow" |
1117 | ||
fd76875c | 1118 | static const char seccomp_actions_avail[] = |
0466bdb9 | 1119 | SECCOMP_RET_KILL_PROCESS_NAME " " |
fd76875c KC |
1120 | SECCOMP_RET_KILL_THREAD_NAME " " |
1121 | SECCOMP_RET_TRAP_NAME " " | |
1122 | SECCOMP_RET_ERRNO_NAME " " | |
1123 | SECCOMP_RET_TRACE_NAME " " | |
1124 | SECCOMP_RET_LOG_NAME " " | |
1125 | SECCOMP_RET_ALLOW_NAME; | |
8e5f1ad1 | 1126 | |
0ddec0fc TH |
1127 | struct seccomp_log_name { |
1128 | u32 log; | |
1129 | const char *name; | |
1130 | }; | |
1131 | ||
1132 | static const struct seccomp_log_name seccomp_log_names[] = { | |
0466bdb9 | 1133 | { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME }, |
fd76875c | 1134 | { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME }, |
0ddec0fc TH |
1135 | { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME }, |
1136 | { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME }, | |
1137 | { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME }, | |
59f5cf44 | 1138 | { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME }, |
0ddec0fc TH |
1139 | { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME }, |
1140 | { } | |
1141 | }; | |
1142 | ||
1143 | static bool seccomp_names_from_actions_logged(char *names, size_t size, | |
beb44aca TH |
1144 | u32 actions_logged, |
1145 | const char *sep) | |
0ddec0fc TH |
1146 | { |
1147 | const struct seccomp_log_name *cur; | |
beb44aca | 1148 | bool append_sep = false; |
0ddec0fc TH |
1149 | |
1150 | for (cur = seccomp_log_names; cur->name && size; cur++) { | |
1151 | ssize_t ret; | |
1152 | ||
1153 | if (!(actions_logged & cur->log)) | |
1154 | continue; | |
1155 | ||
beb44aca TH |
1156 | if (append_sep) { |
1157 | ret = strscpy(names, sep, size); | |
0ddec0fc TH |
1158 | if (ret < 0) |
1159 | return false; | |
1160 | ||
1161 | names += ret; | |
1162 | size -= ret; | |
1163 | } else | |
beb44aca | 1164 | append_sep = true; |
0ddec0fc TH |
1165 | |
1166 | ret = strscpy(names, cur->name, size); | |
1167 | if (ret < 0) | |
1168 | return false; | |
1169 | ||
1170 | names += ret; | |
1171 | size -= ret; | |
1172 | } | |
1173 | ||
1174 | return true; | |
1175 | } | |
1176 | ||
1177 | static bool seccomp_action_logged_from_name(u32 *action_logged, | |
1178 | const char *name) | |
1179 | { | |
1180 | const struct seccomp_log_name *cur; | |
1181 | ||
1182 | for (cur = seccomp_log_names; cur->name; cur++) { | |
1183 | if (!strcmp(cur->name, name)) { | |
1184 | *action_logged = cur->log; | |
1185 | return true; | |
1186 | } | |
1187 | } | |
1188 | ||
1189 | return false; | |
1190 | } | |
1191 | ||
1192 | static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names) | |
1193 | { | |
1194 | char *name; | |
1195 | ||
1196 | *actions_logged = 0; | |
1197 | while ((name = strsep(&names, " ")) && *name) { | |
1198 | u32 action_logged = 0; | |
1199 | ||
1200 | if (!seccomp_action_logged_from_name(&action_logged, name)) | |
1201 | return false; | |
1202 | ||
1203 | *actions_logged |= action_logged; | |
1204 | } | |
1205 | ||
1206 | return true; | |
1207 | } | |
1208 | ||
d013db02 TH |
1209 | static int read_actions_logged(struct ctl_table *ro_table, void __user *buffer, |
1210 | size_t *lenp, loff_t *ppos) | |
0ddec0fc TH |
1211 | { |
1212 | char names[sizeof(seccomp_actions_avail)]; | |
1213 | struct ctl_table table; | |
d013db02 TH |
1214 | |
1215 | memset(names, 0, sizeof(names)); | |
1216 | ||
1217 | if (!seccomp_names_from_actions_logged(names, sizeof(names), | |
beb44aca | 1218 | seccomp_actions_logged, " ")) |
d013db02 TH |
1219 | return -EINVAL; |
1220 | ||
1221 | table = *ro_table; | |
1222 | table.data = names; | |
1223 | table.maxlen = sizeof(names); | |
1224 | return proc_dostring(&table, 0, buffer, lenp, ppos); | |
1225 | } | |
1226 | ||
1227 | static int write_actions_logged(struct ctl_table *ro_table, void __user *buffer, | |
ea6eca77 | 1228 | size_t *lenp, loff_t *ppos, u32 *actions_logged) |
0ddec0fc TH |
1229 | { |
1230 | char names[sizeof(seccomp_actions_avail)]; | |
1231 | struct ctl_table table; | |
1232 | int ret; | |
1233 | ||
d013db02 | 1234 | if (!capable(CAP_SYS_ADMIN)) |
0ddec0fc TH |
1235 | return -EPERM; |
1236 | ||
1237 | memset(names, 0, sizeof(names)); | |
1238 | ||
0ddec0fc TH |
1239 | table = *ro_table; |
1240 | table.data = names; | |
1241 | table.maxlen = sizeof(names); | |
d013db02 | 1242 | ret = proc_dostring(&table, 1, buffer, lenp, ppos); |
0ddec0fc TH |
1243 | if (ret) |
1244 | return ret; | |
1245 | ||
ea6eca77 | 1246 | if (!seccomp_actions_logged_from_names(actions_logged, table.data)) |
d013db02 | 1247 | return -EINVAL; |
0ddec0fc | 1248 | |
ea6eca77 | 1249 | if (*actions_logged & SECCOMP_LOG_ALLOW) |
d013db02 | 1250 | return -EINVAL; |
0ddec0fc | 1251 | |
ea6eca77 | 1252 | seccomp_actions_logged = *actions_logged; |
0ddec0fc TH |
1253 | return 0; |
1254 | } | |
0ddec0fc | 1255 | |
ea6eca77 TH |
1256 | static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged, |
1257 | int ret) | |
1258 | { | |
1259 | char names[sizeof(seccomp_actions_avail)]; | |
1260 | char old_names[sizeof(seccomp_actions_avail)]; | |
1261 | const char *new = names; | |
1262 | const char *old = old_names; | |
0ddec0fc | 1263 | |
ea6eca77 TH |
1264 | if (!audit_enabled) |
1265 | return; | |
1266 | ||
1267 | memset(names, 0, sizeof(names)); | |
1268 | memset(old_names, 0, sizeof(old_names)); | |
1269 | ||
1270 | if (ret) | |
1271 | new = "?"; | |
1272 | else if (!actions_logged) | |
1273 | new = "(none)"; | |
1274 | else if (!seccomp_names_from_actions_logged(names, sizeof(names), | |
1275 | actions_logged, ",")) | |
1276 | new = "?"; | |
1277 | ||
1278 | if (!old_actions_logged) | |
1279 | old = "(none)"; | |
1280 | else if (!seccomp_names_from_actions_logged(old_names, | |
1281 | sizeof(old_names), | |
1282 | old_actions_logged, ",")) | |
1283 | old = "?"; | |
1284 | ||
1285 | return audit_seccomp_actions_logged(new, old, !ret); | |
1286 | } | |
1287 | ||
d013db02 TH |
1288 | static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, |
1289 | void __user *buffer, size_t *lenp, | |
1290 | loff_t *ppos) | |
1291 | { | |
ea6eca77 TH |
1292 | int ret; |
1293 | ||
1294 | if (write) { | |
1295 | u32 actions_logged = 0; | |
1296 | u32 old_actions_logged = seccomp_actions_logged; | |
1297 | ||
1298 | ret = write_actions_logged(ro_table, buffer, lenp, ppos, | |
1299 | &actions_logged); | |
1300 | audit_actions_logged(actions_logged, old_actions_logged, ret); | |
1301 | } else | |
1302 | ret = read_actions_logged(ro_table, buffer, lenp, ppos); | |
1303 | ||
1304 | return ret; | |
0ddec0fc TH |
1305 | } |
1306 | ||
8e5f1ad1 TH |
1307 | static struct ctl_path seccomp_sysctl_path[] = { |
1308 | { .procname = "kernel", }, | |
1309 | { .procname = "seccomp", }, | |
1310 | { } | |
1311 | }; | |
1312 | ||
1313 | static struct ctl_table seccomp_sysctl_table[] = { | |
1314 | { | |
1315 | .procname = "actions_avail", | |
1316 | .data = (void *) &seccomp_actions_avail, | |
1317 | .maxlen = sizeof(seccomp_actions_avail), | |
1318 | .mode = 0444, | |
1319 | .proc_handler = proc_dostring, | |
1320 | }, | |
0ddec0fc TH |
1321 | { |
1322 | .procname = "actions_logged", | |
1323 | .mode = 0644, | |
1324 | .proc_handler = seccomp_actions_logged_handler, | |
1325 | }, | |
8e5f1ad1 TH |
1326 | { } |
1327 | }; | |
1328 | ||
1329 | static int __init seccomp_sysctl_init(void) | |
1330 | { | |
1331 | struct ctl_table_header *hdr; | |
1332 | ||
1333 | hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table); | |
1334 | if (!hdr) | |
1335 | pr_warn("seccomp: sysctl registration failed\n"); | |
1336 | else | |
1337 | kmemleak_not_leak(hdr); | |
1338 | ||
1339 | return 0; | |
1340 | } | |
1341 | ||
1342 | device_initcall(seccomp_sysctl_init) | |
1343 | ||
1344 | #endif /* CONFIG_SYSCTL */ |