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1da177e4 LT |
1 | /* |
2 | * linux/kernel/seccomp.c | |
3 | * | |
4 | * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com> | |
5 | * | |
e2cfabdf WD |
6 | * Copyright (C) 2012 Google, Inc. |
7 | * Will Drewry <wad@chromium.org> | |
8 | * | |
9 | * This defines a simple but solid secure-computing facility. | |
10 | * | |
11 | * Mode 1 uses a fixed list of allowed system calls. | |
12 | * Mode 2 allows user-defined system call filters in the form | |
13 | * of Berkeley Packet Filters/Linux Socket Filters. | |
1da177e4 LT |
14 | */ |
15 | ||
0b5fa229 | 16 | #include <linux/refcount.h> |
85e7bac3 | 17 | #include <linux/audit.h> |
5b101740 | 18 | #include <linux/compat.h> |
b25e6716 | 19 | #include <linux/coredump.h> |
8e5f1ad1 | 20 | #include <linux/kmemleak.h> |
e2cfabdf | 21 | #include <linux/sched.h> |
68db0cf1 | 22 | #include <linux/sched/task_stack.h> |
e2cfabdf | 23 | #include <linux/seccomp.h> |
c8bee430 | 24 | #include <linux/slab.h> |
48dc92b9 | 25 | #include <linux/syscalls.h> |
8e5f1ad1 | 26 | #include <linux/sysctl.h> |
1da177e4 | 27 | |
a4412fc9 | 28 | #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER |
e2cfabdf | 29 | #include <asm/syscall.h> |
a4412fc9 | 30 | #endif |
e2cfabdf WD |
31 | |
32 | #ifdef CONFIG_SECCOMP_FILTER | |
e2cfabdf | 33 | #include <linux/filter.h> |
c2e1f2e3 | 34 | #include <linux/pid.h> |
fb0fadf9 | 35 | #include <linux/ptrace.h> |
e2cfabdf | 36 | #include <linux/security.h> |
e2cfabdf WD |
37 | #include <linux/tracehook.h> |
38 | #include <linux/uaccess.h> | |
39 | ||
40 | /** | |
41 | * struct seccomp_filter - container for seccomp BPF programs | |
42 | * | |
43 | * @usage: reference count to manage the object lifetime. | |
44 | * get/put helpers should be used when accessing an instance | |
45 | * outside of a lifetime-guarded section. In general, this | |
46 | * is only needed for handling filters shared across tasks. | |
e66a3997 | 47 | * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged |
e2cfabdf | 48 | * @prev: points to a previously installed, or inherited, filter |
285fdfc5 | 49 | * @prog: the BPF program to evaluate |
e2cfabdf WD |
50 | * |
51 | * seccomp_filter objects are organized in a tree linked via the @prev | |
52 | * pointer. For any task, it appears to be a singly-linked list starting | |
53 | * with current->seccomp.filter, the most recently attached or inherited filter. | |
54 | * However, multiple filters may share a @prev node, by way of fork(), which | |
55 | * results in a unidirectional tree existing in memory. This is similar to | |
56 | * how namespaces work. | |
57 | * | |
58 | * seccomp_filter objects should never be modified after being attached | |
59 | * to a task_struct (other than @usage). | |
60 | */ | |
61 | struct seccomp_filter { | |
0b5fa229 | 62 | refcount_t usage; |
e66a3997 | 63 | bool log; |
e2cfabdf | 64 | struct seccomp_filter *prev; |
7ae457c1 | 65 | struct bpf_prog *prog; |
e2cfabdf WD |
66 | }; |
67 | ||
68 | /* Limit any path through the tree to 256KB worth of instructions. */ | |
69 | #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) | |
70 | ||
bd4cf0ed | 71 | /* |
e2cfabdf WD |
72 | * Endianness is explicitly ignored and left for BPF program authors to manage |
73 | * as per the specific architecture. | |
74 | */ | |
bd4cf0ed | 75 | static void populate_seccomp_data(struct seccomp_data *sd) |
e2cfabdf | 76 | { |
bd4cf0ed AS |
77 | struct task_struct *task = current; |
78 | struct pt_regs *regs = task_pt_regs(task); | |
2eac7648 | 79 | unsigned long args[6]; |
e2cfabdf | 80 | |
bd4cf0ed | 81 | sd->nr = syscall_get_nr(task, regs); |
0b747172 | 82 | sd->arch = syscall_get_arch(); |
2eac7648 DB |
83 | syscall_get_arguments(task, regs, 0, 6, args); |
84 | sd->args[0] = args[0]; | |
85 | sd->args[1] = args[1]; | |
86 | sd->args[2] = args[2]; | |
87 | sd->args[3] = args[3]; | |
88 | sd->args[4] = args[4]; | |
89 | sd->args[5] = args[5]; | |
bd4cf0ed | 90 | sd->instruction_pointer = KSTK_EIP(task); |
e2cfabdf WD |
91 | } |
92 | ||
93 | /** | |
94 | * seccomp_check_filter - verify seccomp filter code | |
95 | * @filter: filter to verify | |
96 | * @flen: length of filter | |
97 | * | |
4df95ff4 | 98 | * Takes a previously checked filter (by bpf_check_classic) and |
e2cfabdf WD |
99 | * redirects all filter code that loads struct sk_buff data |
100 | * and related data through seccomp_bpf_load. It also | |
101 | * enforces length and alignment checking of those loads. | |
102 | * | |
103 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
104 | */ | |
105 | static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) | |
106 | { | |
107 | int pc; | |
108 | for (pc = 0; pc < flen; pc++) { | |
109 | struct sock_filter *ftest = &filter[pc]; | |
110 | u16 code = ftest->code; | |
111 | u32 k = ftest->k; | |
112 | ||
113 | switch (code) { | |
34805931 | 114 | case BPF_LD | BPF_W | BPF_ABS: |
bd4cf0ed | 115 | ftest->code = BPF_LDX | BPF_W | BPF_ABS; |
e2cfabdf WD |
116 | /* 32-bit aligned and not out of bounds. */ |
117 | if (k >= sizeof(struct seccomp_data) || k & 3) | |
118 | return -EINVAL; | |
119 | continue; | |
34805931 | 120 | case BPF_LD | BPF_W | BPF_LEN: |
bd4cf0ed | 121 | ftest->code = BPF_LD | BPF_IMM; |
e2cfabdf WD |
122 | ftest->k = sizeof(struct seccomp_data); |
123 | continue; | |
34805931 | 124 | case BPF_LDX | BPF_W | BPF_LEN: |
bd4cf0ed | 125 | ftest->code = BPF_LDX | BPF_IMM; |
e2cfabdf WD |
126 | ftest->k = sizeof(struct seccomp_data); |
127 | continue; | |
128 | /* Explicitly include allowed calls. */ | |
34805931 DB |
129 | case BPF_RET | BPF_K: |
130 | case BPF_RET | BPF_A: | |
131 | case BPF_ALU | BPF_ADD | BPF_K: | |
132 | case BPF_ALU | BPF_ADD | BPF_X: | |
133 | case BPF_ALU | BPF_SUB | BPF_K: | |
134 | case BPF_ALU | BPF_SUB | BPF_X: | |
135 | case BPF_ALU | BPF_MUL | BPF_K: | |
136 | case BPF_ALU | BPF_MUL | BPF_X: | |
137 | case BPF_ALU | BPF_DIV | BPF_K: | |
138 | case BPF_ALU | BPF_DIV | BPF_X: | |
139 | case BPF_ALU | BPF_AND | BPF_K: | |
140 | case BPF_ALU | BPF_AND | BPF_X: | |
141 | case BPF_ALU | BPF_OR | BPF_K: | |
142 | case BPF_ALU | BPF_OR | BPF_X: | |
143 | case BPF_ALU | BPF_XOR | BPF_K: | |
144 | case BPF_ALU | BPF_XOR | BPF_X: | |
145 | case BPF_ALU | BPF_LSH | BPF_K: | |
146 | case BPF_ALU | BPF_LSH | BPF_X: | |
147 | case BPF_ALU | BPF_RSH | BPF_K: | |
148 | case BPF_ALU | BPF_RSH | BPF_X: | |
149 | case BPF_ALU | BPF_NEG: | |
150 | case BPF_LD | BPF_IMM: | |
151 | case BPF_LDX | BPF_IMM: | |
152 | case BPF_MISC | BPF_TAX: | |
153 | case BPF_MISC | BPF_TXA: | |
154 | case BPF_LD | BPF_MEM: | |
155 | case BPF_LDX | BPF_MEM: | |
156 | case BPF_ST: | |
157 | case BPF_STX: | |
158 | case BPF_JMP | BPF_JA: | |
159 | case BPF_JMP | BPF_JEQ | BPF_K: | |
160 | case BPF_JMP | BPF_JEQ | BPF_X: | |
161 | case BPF_JMP | BPF_JGE | BPF_K: | |
162 | case BPF_JMP | BPF_JGE | BPF_X: | |
163 | case BPF_JMP | BPF_JGT | BPF_K: | |
164 | case BPF_JMP | BPF_JGT | BPF_X: | |
165 | case BPF_JMP | BPF_JSET | BPF_K: | |
166 | case BPF_JMP | BPF_JSET | BPF_X: | |
e2cfabdf WD |
167 | continue; |
168 | default: | |
169 | return -EINVAL; | |
170 | } | |
171 | } | |
172 | return 0; | |
173 | } | |
174 | ||
175 | /** | |
285fdfc5 MS |
176 | * seccomp_run_filters - evaluates all seccomp filters against @sd |
177 | * @sd: optional seccomp data to be passed to filters | |
deb4de8b KC |
178 | * @match: stores struct seccomp_filter that resulted in the return value, |
179 | * unless filter returned SECCOMP_RET_ALLOW, in which case it will | |
180 | * be unchanged. | |
e2cfabdf WD |
181 | * |
182 | * Returns valid seccomp BPF response codes. | |
183 | */ | |
0466bdb9 | 184 | #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL))) |
deb4de8b KC |
185 | static u32 seccomp_run_filters(const struct seccomp_data *sd, |
186 | struct seccomp_filter **match) | |
e2cfabdf | 187 | { |
d39bd00d | 188 | struct seccomp_data sd_local; |
acf3b2c7 | 189 | u32 ret = SECCOMP_RET_ALLOW; |
8225d385 PK |
190 | /* Make sure cross-thread synced filter points somewhere sane. */ |
191 | struct seccomp_filter *f = | |
192 | lockless_dereference(current->seccomp.filter); | |
acf3b2c7 WD |
193 | |
194 | /* Ensure unexpected behavior doesn't result in failing open. */ | |
3ba2530c | 195 | if (unlikely(WARN_ON(f == NULL))) |
4d3b0b05 | 196 | return SECCOMP_RET_KILL_PROCESS; |
acf3b2c7 | 197 | |
d39bd00d AL |
198 | if (!sd) { |
199 | populate_seccomp_data(&sd_local); | |
200 | sd = &sd_local; | |
201 | } | |
bd4cf0ed | 202 | |
e2cfabdf WD |
203 | /* |
204 | * All filters in the list are evaluated and the lowest BPF return | |
acf3b2c7 | 205 | * value always takes priority (ignoring the DATA). |
e2cfabdf | 206 | */ |
3ba2530c | 207 | for (; f; f = f->prev) { |
88575199 | 208 | u32 cur_ret = BPF_PROG_RUN(f->prog, sd); |
8f577cad | 209 | |
0466bdb9 | 210 | if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) { |
acf3b2c7 | 211 | ret = cur_ret; |
deb4de8b KC |
212 | *match = f; |
213 | } | |
e2cfabdf WD |
214 | } |
215 | return ret; | |
216 | } | |
1f41b450 | 217 | #endif /* CONFIG_SECCOMP_FILTER */ |
e2cfabdf | 218 | |
1f41b450 KC |
219 | static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) |
220 | { | |
69f6a34b | 221 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 222 | |
1f41b450 KC |
223 | if (current->seccomp.mode && current->seccomp.mode != seccomp_mode) |
224 | return false; | |
225 | ||
226 | return true; | |
227 | } | |
228 | ||
3ba2530c KC |
229 | static inline void seccomp_assign_mode(struct task_struct *task, |
230 | unsigned long seccomp_mode) | |
1f41b450 | 231 | { |
69f6a34b | 232 | assert_spin_locked(&task->sighand->siglock); |
dbd95212 | 233 | |
3ba2530c KC |
234 | task->seccomp.mode = seccomp_mode; |
235 | /* | |
236 | * Make sure TIF_SECCOMP cannot be set before the mode (and | |
237 | * filter) is set. | |
238 | */ | |
239 | smp_mb__before_atomic(); | |
240 | set_tsk_thread_flag(task, TIF_SECCOMP); | |
1f41b450 KC |
241 | } |
242 | ||
243 | #ifdef CONFIG_SECCOMP_FILTER | |
c2e1f2e3 KC |
244 | /* Returns 1 if the parent is an ancestor of the child. */ |
245 | static int is_ancestor(struct seccomp_filter *parent, | |
246 | struct seccomp_filter *child) | |
247 | { | |
248 | /* NULL is the root ancestor. */ | |
249 | if (parent == NULL) | |
250 | return 1; | |
251 | for (; child; child = child->prev) | |
252 | if (child == parent) | |
253 | return 1; | |
254 | return 0; | |
255 | } | |
256 | ||
257 | /** | |
258 | * seccomp_can_sync_threads: checks if all threads can be synchronized | |
259 | * | |
260 | * Expects sighand and cred_guard_mutex locks to be held. | |
261 | * | |
262 | * Returns 0 on success, -ve on error, or the pid of a thread which was | |
263 | * either not in the correct seccomp mode or it did not have an ancestral | |
264 | * seccomp filter. | |
265 | */ | |
266 | static inline pid_t seccomp_can_sync_threads(void) | |
267 | { | |
268 | struct task_struct *thread, *caller; | |
269 | ||
270 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 271 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
272 | |
273 | /* Validate all threads being eligible for synchronization. */ | |
274 | caller = current; | |
275 | for_each_thread(caller, thread) { | |
276 | pid_t failed; | |
277 | ||
278 | /* Skip current, since it is initiating the sync. */ | |
279 | if (thread == caller) | |
280 | continue; | |
281 | ||
282 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || | |
283 | (thread->seccomp.mode == SECCOMP_MODE_FILTER && | |
284 | is_ancestor(thread->seccomp.filter, | |
285 | caller->seccomp.filter))) | |
286 | continue; | |
287 | ||
288 | /* Return the first thread that cannot be synchronized. */ | |
289 | failed = task_pid_vnr(thread); | |
290 | /* If the pid cannot be resolved, then return -ESRCH */ | |
291 | if (unlikely(WARN_ON(failed == 0))) | |
292 | failed = -ESRCH; | |
293 | return failed; | |
294 | } | |
295 | ||
296 | return 0; | |
297 | } | |
298 | ||
299 | /** | |
300 | * seccomp_sync_threads: sets all threads to use current's filter | |
301 | * | |
302 | * Expects sighand and cred_guard_mutex locks to be held, and for | |
303 | * seccomp_can_sync_threads() to have returned success already | |
304 | * without dropping the locks. | |
305 | * | |
306 | */ | |
307 | static inline void seccomp_sync_threads(void) | |
308 | { | |
309 | struct task_struct *thread, *caller; | |
310 | ||
311 | BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex)); | |
69f6a34b | 312 | assert_spin_locked(¤t->sighand->siglock); |
c2e1f2e3 KC |
313 | |
314 | /* Synchronize all threads. */ | |
315 | caller = current; | |
316 | for_each_thread(caller, thread) { | |
317 | /* Skip current, since it needs no changes. */ | |
318 | if (thread == caller) | |
319 | continue; | |
320 | ||
321 | /* Get a task reference for the new leaf node. */ | |
322 | get_seccomp_filter(caller); | |
323 | /* | |
324 | * Drop the task reference to the shared ancestor since | |
325 | * current's path will hold a reference. (This also | |
326 | * allows a put before the assignment.) | |
327 | */ | |
328 | put_seccomp_filter(thread); | |
329 | smp_store_release(&thread->seccomp.filter, | |
330 | caller->seccomp.filter); | |
103502a3 JH |
331 | |
332 | /* | |
333 | * Don't let an unprivileged task work around | |
334 | * the no_new_privs restriction by creating | |
335 | * a thread that sets it up, enters seccomp, | |
336 | * then dies. | |
337 | */ | |
338 | if (task_no_new_privs(caller)) | |
339 | task_set_no_new_privs(thread); | |
340 | ||
c2e1f2e3 KC |
341 | /* |
342 | * Opt the other thread into seccomp if needed. | |
343 | * As threads are considered to be trust-realm | |
344 | * equivalent (see ptrace_may_access), it is safe to | |
345 | * allow one thread to transition the other. | |
346 | */ | |
103502a3 | 347 | if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) |
c2e1f2e3 | 348 | seccomp_assign_mode(thread, SECCOMP_MODE_FILTER); |
c2e1f2e3 KC |
349 | } |
350 | } | |
351 | ||
e2cfabdf | 352 | /** |
c8bee430 | 353 | * seccomp_prepare_filter: Prepares a seccomp filter for use. |
e2cfabdf WD |
354 | * @fprog: BPF program to install |
355 | * | |
c8bee430 | 356 | * Returns filter on success or an ERR_PTR on failure. |
e2cfabdf | 357 | */ |
c8bee430 | 358 | static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) |
e2cfabdf | 359 | { |
ac67eb2c DB |
360 | struct seccomp_filter *sfilter; |
361 | int ret; | |
97f2645f | 362 | const bool save_orig = IS_ENABLED(CONFIG_CHECKPOINT_RESTORE); |
e2cfabdf WD |
363 | |
364 | if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) | |
c8bee430 | 365 | return ERR_PTR(-EINVAL); |
d9e12f42 | 366 | |
c8bee430 | 367 | BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); |
e2cfabdf WD |
368 | |
369 | /* | |
119ce5c8 | 370 | * Installing a seccomp filter requires that the task has |
e2cfabdf WD |
371 | * CAP_SYS_ADMIN in its namespace or be running with no_new_privs. |
372 | * This avoids scenarios where unprivileged tasks can affect the | |
373 | * behavior of privileged children. | |
374 | */ | |
1d4457f9 | 375 | if (!task_no_new_privs(current) && |
e2cfabdf WD |
376 | security_capable_noaudit(current_cred(), current_user_ns(), |
377 | CAP_SYS_ADMIN) != 0) | |
c8bee430 | 378 | return ERR_PTR(-EACCES); |
e2cfabdf | 379 | |
bd4cf0ed | 380 | /* Allocate a new seccomp_filter */ |
ac67eb2c DB |
381 | sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN); |
382 | if (!sfilter) | |
d9e12f42 | 383 | return ERR_PTR(-ENOMEM); |
ac67eb2c DB |
384 | |
385 | ret = bpf_prog_create_from_user(&sfilter->prog, fprog, | |
f8e529ed | 386 | seccomp_check_filter, save_orig); |
ac67eb2c DB |
387 | if (ret < 0) { |
388 | kfree(sfilter); | |
389 | return ERR_PTR(ret); | |
d9e12f42 | 390 | } |
bd4cf0ed | 391 | |
0b5fa229 | 392 | refcount_set(&sfilter->usage, 1); |
e2cfabdf | 393 | |
ac67eb2c | 394 | return sfilter; |
e2cfabdf WD |
395 | } |
396 | ||
397 | /** | |
c8bee430 | 398 | * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog |
e2cfabdf WD |
399 | * @user_filter: pointer to the user data containing a sock_fprog. |
400 | * | |
401 | * Returns 0 on success and non-zero otherwise. | |
402 | */ | |
c8bee430 KC |
403 | static struct seccomp_filter * |
404 | seccomp_prepare_user_filter(const char __user *user_filter) | |
e2cfabdf WD |
405 | { |
406 | struct sock_fprog fprog; | |
c8bee430 | 407 | struct seccomp_filter *filter = ERR_PTR(-EFAULT); |
e2cfabdf WD |
408 | |
409 | #ifdef CONFIG_COMPAT | |
5c38065e | 410 | if (in_compat_syscall()) { |
e2cfabdf WD |
411 | struct compat_sock_fprog fprog32; |
412 | if (copy_from_user(&fprog32, user_filter, sizeof(fprog32))) | |
413 | goto out; | |
414 | fprog.len = fprog32.len; | |
415 | fprog.filter = compat_ptr(fprog32.filter); | |
416 | } else /* falls through to the if below. */ | |
417 | #endif | |
418 | if (copy_from_user(&fprog, user_filter, sizeof(fprog))) | |
419 | goto out; | |
c8bee430 | 420 | filter = seccomp_prepare_filter(&fprog); |
e2cfabdf | 421 | out: |
c8bee430 KC |
422 | return filter; |
423 | } | |
424 | ||
425 | /** | |
426 | * seccomp_attach_filter: validate and attach filter | |
427 | * @flags: flags to change filter behavior | |
428 | * @filter: seccomp filter to add to the current process | |
429 | * | |
dbd95212 KC |
430 | * Caller must be holding current->sighand->siglock lock. |
431 | * | |
c8bee430 KC |
432 | * Returns 0 on success, -ve on error. |
433 | */ | |
434 | static long seccomp_attach_filter(unsigned int flags, | |
435 | struct seccomp_filter *filter) | |
436 | { | |
437 | unsigned long total_insns; | |
438 | struct seccomp_filter *walker; | |
439 | ||
69f6a34b | 440 | assert_spin_locked(¤t->sighand->siglock); |
dbd95212 | 441 | |
c8bee430 KC |
442 | /* Validate resulting filter length. */ |
443 | total_insns = filter->prog->len; | |
444 | for (walker = current->seccomp.filter; walker; walker = walker->prev) | |
445 | total_insns += walker->prog->len + 4; /* 4 instr penalty */ | |
446 | if (total_insns > MAX_INSNS_PER_PATH) | |
447 | return -ENOMEM; | |
448 | ||
c2e1f2e3 KC |
449 | /* If thread sync has been requested, check that it is possible. */ |
450 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) { | |
451 | int ret; | |
452 | ||
453 | ret = seccomp_can_sync_threads(); | |
454 | if (ret) | |
455 | return ret; | |
456 | } | |
457 | ||
e66a3997 TH |
458 | /* Set log flag, if present. */ |
459 | if (flags & SECCOMP_FILTER_FLAG_LOG) | |
460 | filter->log = true; | |
461 | ||
c8bee430 KC |
462 | /* |
463 | * If there is an existing filter, make it the prev and don't drop its | |
464 | * task reference. | |
465 | */ | |
466 | filter->prev = current->seccomp.filter; | |
467 | current->seccomp.filter = filter; | |
468 | ||
c2e1f2e3 KC |
469 | /* Now that the new filter is in place, synchronize to all threads. */ |
470 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) | |
471 | seccomp_sync_threads(); | |
472 | ||
c8bee430 | 473 | return 0; |
e2cfabdf WD |
474 | } |
475 | ||
66a733ea ON |
476 | void __get_seccomp_filter(struct seccomp_filter *filter) |
477 | { | |
478 | /* Reference count is bounded by the number of total processes. */ | |
479 | refcount_inc(&filter->usage); | |
480 | } | |
481 | ||
e2cfabdf WD |
482 | /* get_seccomp_filter - increments the reference count of the filter on @tsk */ |
483 | void get_seccomp_filter(struct task_struct *tsk) | |
484 | { | |
485 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
486 | if (!orig) | |
487 | return; | |
66a733ea | 488 | __get_seccomp_filter(orig); |
e2cfabdf WD |
489 | } |
490 | ||
c8bee430 KC |
491 | static inline void seccomp_filter_free(struct seccomp_filter *filter) |
492 | { | |
493 | if (filter) { | |
bab18991 | 494 | bpf_prog_destroy(filter->prog); |
c8bee430 KC |
495 | kfree(filter); |
496 | } | |
497 | } | |
498 | ||
66a733ea | 499 | static void __put_seccomp_filter(struct seccomp_filter *orig) |
e2cfabdf | 500 | { |
e2cfabdf | 501 | /* Clean up single-reference branches iteratively. */ |
0b5fa229 | 502 | while (orig && refcount_dec_and_test(&orig->usage)) { |
e2cfabdf WD |
503 | struct seccomp_filter *freeme = orig; |
504 | orig = orig->prev; | |
c8bee430 | 505 | seccomp_filter_free(freeme); |
e2cfabdf WD |
506 | } |
507 | } | |
bb6ea430 | 508 | |
66a733ea ON |
509 | /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */ |
510 | void put_seccomp_filter(struct task_struct *tsk) | |
511 | { | |
512 | __put_seccomp_filter(tsk->seccomp.filter); | |
513 | } | |
514 | ||
b25e6716 MF |
515 | static void seccomp_init_siginfo(siginfo_t *info, int syscall, int reason) |
516 | { | |
517 | memset(info, 0, sizeof(*info)); | |
518 | info->si_signo = SIGSYS; | |
519 | info->si_code = SYS_SECCOMP; | |
520 | info->si_call_addr = (void __user *)KSTK_EIP(current); | |
521 | info->si_errno = reason; | |
522 | info->si_arch = syscall_get_arch(); | |
523 | info->si_syscall = syscall; | |
524 | } | |
525 | ||
bb6ea430 WD |
526 | /** |
527 | * seccomp_send_sigsys - signals the task to allow in-process syscall emulation | |
528 | * @syscall: syscall number to send to userland | |
529 | * @reason: filter-supplied reason code to send to userland (via si_errno) | |
530 | * | |
531 | * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. | |
532 | */ | |
533 | static void seccomp_send_sigsys(int syscall, int reason) | |
534 | { | |
535 | struct siginfo info; | |
b25e6716 | 536 | seccomp_init_siginfo(&info, syscall, reason); |
bb6ea430 WD |
537 | force_sig_info(SIGSYS, &info, current); |
538 | } | |
e2cfabdf | 539 | #endif /* CONFIG_SECCOMP_FILTER */ |
1da177e4 | 540 | |
0ddec0fc | 541 | /* For use with seccomp_actions_logged */ |
4d3b0b05 KC |
542 | #define SECCOMP_LOG_KILL_PROCESS (1 << 0) |
543 | #define SECCOMP_LOG_KILL_THREAD (1 << 1) | |
0ddec0fc TH |
544 | #define SECCOMP_LOG_TRAP (1 << 2) |
545 | #define SECCOMP_LOG_ERRNO (1 << 3) | |
546 | #define SECCOMP_LOG_TRACE (1 << 4) | |
59f5cf44 TH |
547 | #define SECCOMP_LOG_LOG (1 << 5) |
548 | #define SECCOMP_LOG_ALLOW (1 << 6) | |
0ddec0fc | 549 | |
4d3b0b05 KC |
550 | static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS | |
551 | SECCOMP_LOG_KILL_THREAD | | |
fd76875c KC |
552 | SECCOMP_LOG_TRAP | |
553 | SECCOMP_LOG_ERRNO | | |
554 | SECCOMP_LOG_TRACE | | |
59f5cf44 | 555 | SECCOMP_LOG_LOG; |
0ddec0fc | 556 | |
e66a3997 TH |
557 | static inline void seccomp_log(unsigned long syscall, long signr, u32 action, |
558 | bool requested) | |
0ddec0fc TH |
559 | { |
560 | bool log = false; | |
561 | ||
562 | switch (action) { | |
563 | case SECCOMP_RET_ALLOW: | |
e66a3997 | 564 | break; |
0ddec0fc | 565 | case SECCOMP_RET_TRAP: |
e66a3997 TH |
566 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP; |
567 | break; | |
0ddec0fc | 568 | case SECCOMP_RET_ERRNO: |
e66a3997 TH |
569 | log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO; |
570 | break; | |
0ddec0fc | 571 | case SECCOMP_RET_TRACE: |
e66a3997 | 572 | log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE; |
0ddec0fc | 573 | break; |
59f5cf44 TH |
574 | case SECCOMP_RET_LOG: |
575 | log = seccomp_actions_logged & SECCOMP_LOG_LOG; | |
576 | break; | |
fd76875c | 577 | case SECCOMP_RET_KILL_THREAD: |
fd76875c | 578 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD; |
4d3b0b05 KC |
579 | break; |
580 | case SECCOMP_RET_KILL_PROCESS: | |
581 | default: | |
582 | log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS; | |
0ddec0fc TH |
583 | } |
584 | ||
585 | /* | |
fd76875c | 586 | * Force an audit message to be emitted when the action is RET_KILL_*, |
59f5cf44 TH |
587 | * RET_LOG, or the FILTER_FLAG_LOG bit was set and the action is |
588 | * allowed to be logged by the admin. | |
0ddec0fc TH |
589 | */ |
590 | if (log) | |
591 | return __audit_seccomp(syscall, signr, action); | |
592 | ||
593 | /* | |
594 | * Let the audit subsystem decide if the action should be audited based | |
595 | * on whether the current task itself is being audited. | |
596 | */ | |
597 | return audit_seccomp(syscall, signr, action); | |
598 | } | |
599 | ||
1da177e4 LT |
600 | /* |
601 | * Secure computing mode 1 allows only read/write/exit/sigreturn. | |
602 | * To be fully secure this must be combined with rlimit | |
603 | * to limit the stack allocations too. | |
604 | */ | |
cb4253aa | 605 | static const int mode1_syscalls[] = { |
1da177e4 LT |
606 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, |
607 | 0, /* null terminated */ | |
608 | }; | |
609 | ||
a4412fc9 | 610 | static void __secure_computing_strict(int this_syscall) |
1da177e4 | 611 | { |
cb4253aa | 612 | const int *syscall_whitelist = mode1_syscalls; |
a4412fc9 | 613 | #ifdef CONFIG_COMPAT |
5c38065e | 614 | if (in_compat_syscall()) |
c983f0e8 | 615 | syscall_whitelist = get_compat_mode1_syscalls(); |
a4412fc9 AL |
616 | #endif |
617 | do { | |
618 | if (*syscall_whitelist == this_syscall) | |
619 | return; | |
620 | } while (*++syscall_whitelist); | |
621 | ||
622 | #ifdef SECCOMP_DEBUG | |
623 | dump_stack(); | |
624 | #endif | |
fd76875c | 625 | seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true); |
a4412fc9 AL |
626 | do_exit(SIGKILL); |
627 | } | |
628 | ||
629 | #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER | |
630 | void secure_computing_strict(int this_syscall) | |
631 | { | |
632 | int mode = current->seccomp.mode; | |
633 | ||
97f2645f | 634 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 TA |
635 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
636 | return; | |
637 | ||
221272f9 | 638 | if (mode == SECCOMP_MODE_DISABLED) |
a4412fc9 AL |
639 | return; |
640 | else if (mode == SECCOMP_MODE_STRICT) | |
641 | __secure_computing_strict(this_syscall); | |
642 | else | |
643 | BUG(); | |
644 | } | |
645 | #else | |
13aa72f0 AL |
646 | |
647 | #ifdef CONFIG_SECCOMP_FILTER | |
ce6526e8 KC |
648 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
649 | const bool recheck_after_trace) | |
13aa72f0 AL |
650 | { |
651 | u32 filter_ret, action; | |
deb4de8b | 652 | struct seccomp_filter *match = NULL; |
13aa72f0 | 653 | int data; |
1da177e4 | 654 | |
3ba2530c KC |
655 | /* |
656 | * Make sure that any changes to mode from another thread have | |
657 | * been seen after TIF_SECCOMP was seen. | |
658 | */ | |
659 | rmb(); | |
660 | ||
deb4de8b | 661 | filter_ret = seccomp_run_filters(sd, &match); |
13aa72f0 | 662 | data = filter_ret & SECCOMP_RET_DATA; |
0466bdb9 | 663 | action = filter_ret & SECCOMP_RET_ACTION_FULL; |
13aa72f0 AL |
664 | |
665 | switch (action) { | |
666 | case SECCOMP_RET_ERRNO: | |
580c57f1 KC |
667 | /* Set low-order bits as an errno, capped at MAX_ERRNO. */ |
668 | if (data > MAX_ERRNO) | |
669 | data = MAX_ERRNO; | |
d39bd00d | 670 | syscall_set_return_value(current, task_pt_regs(current), |
13aa72f0 AL |
671 | -data, 0); |
672 | goto skip; | |
673 | ||
674 | case SECCOMP_RET_TRAP: | |
675 | /* Show the handler the original registers. */ | |
d39bd00d | 676 | syscall_rollback(current, task_pt_regs(current)); |
13aa72f0 AL |
677 | /* Let the filter pass back 16 bits of data. */ |
678 | seccomp_send_sigsys(this_syscall, data); | |
679 | goto skip; | |
680 | ||
681 | case SECCOMP_RET_TRACE: | |
ce6526e8 KC |
682 | /* We've been put in this state by the ptracer already. */ |
683 | if (recheck_after_trace) | |
684 | return 0; | |
685 | ||
8112c4f1 KC |
686 | /* ENOSYS these calls if there is no tracer attached. */ |
687 | if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { | |
688 | syscall_set_return_value(current, | |
689 | task_pt_regs(current), | |
690 | -ENOSYS, 0); | |
691 | goto skip; | |
692 | } | |
693 | ||
694 | /* Allow the BPF to provide the event message */ | |
695 | ptrace_event(PTRACE_EVENT_SECCOMP, data); | |
696 | /* | |
697 | * The delivery of a fatal signal during event | |
485a252a KC |
698 | * notification may silently skip tracer notification, |
699 | * which could leave us with a potentially unmodified | |
700 | * syscall that the tracer would have liked to have | |
701 | * changed. Since the process is about to die, we just | |
702 | * force the syscall to be skipped and let the signal | |
703 | * kill the process and correctly handle any tracer exit | |
704 | * notifications. | |
8112c4f1 KC |
705 | */ |
706 | if (fatal_signal_pending(current)) | |
485a252a | 707 | goto skip; |
8112c4f1 KC |
708 | /* Check if the tracer forced the syscall to be skipped. */ |
709 | this_syscall = syscall_get_nr(current, task_pt_regs(current)); | |
710 | if (this_syscall < 0) | |
711 | goto skip; | |
712 | ||
ce6526e8 KC |
713 | /* |
714 | * Recheck the syscall, since it may have changed. This | |
715 | * intentionally uses a NULL struct seccomp_data to force | |
716 | * a reload of all registers. This does not goto skip since | |
717 | * a skip would have already been reported. | |
718 | */ | |
719 | if (__seccomp_filter(this_syscall, NULL, true)) | |
720 | return -1; | |
721 | ||
8112c4f1 | 722 | return 0; |
13aa72f0 | 723 | |
59f5cf44 TH |
724 | case SECCOMP_RET_LOG: |
725 | seccomp_log(this_syscall, 0, action, true); | |
726 | return 0; | |
727 | ||
13aa72f0 | 728 | case SECCOMP_RET_ALLOW: |
deb4de8b KC |
729 | /* |
730 | * Note that the "match" filter will always be NULL for | |
731 | * this action since SECCOMP_RET_ALLOW is the starting | |
732 | * state in seccomp_run_filters(). | |
733 | */ | |
8112c4f1 | 734 | return 0; |
13aa72f0 | 735 | |
fd76875c | 736 | case SECCOMP_RET_KILL_THREAD: |
4d3b0b05 | 737 | case SECCOMP_RET_KILL_PROCESS: |
131b6351 | 738 | default: |
e66a3997 | 739 | seccomp_log(this_syscall, SIGSYS, action, true); |
d7276e32 | 740 | /* Dump core only if this is the last remaining thread. */ |
4d3b0b05 KC |
741 | if (action == SECCOMP_RET_KILL_PROCESS || |
742 | get_nr_threads(current) == 1) { | |
131b6351 KC |
743 | siginfo_t info; |
744 | ||
d7276e32 KC |
745 | /* Show the original registers in the dump. */ |
746 | syscall_rollback(current, task_pt_regs(current)); | |
747 | /* Trigger a manual coredump since do_exit skips it. */ | |
748 | seccomp_init_siginfo(&info, this_syscall, data); | |
749 | do_coredump(&info); | |
750 | } | |
4d3b0b05 KC |
751 | if (action == SECCOMP_RET_KILL_PROCESS) |
752 | do_group_exit(SIGSYS); | |
753 | else | |
754 | do_exit(SIGSYS); | |
13aa72f0 AL |
755 | } |
756 | ||
757 | unreachable(); | |
758 | ||
759 | skip: | |
e66a3997 | 760 | seccomp_log(this_syscall, 0, action, match ? match->log : false); |
8112c4f1 KC |
761 | return -1; |
762 | } | |
763 | #else | |
ce6526e8 KC |
764 | static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, |
765 | const bool recheck_after_trace) | |
8112c4f1 KC |
766 | { |
767 | BUG(); | |
13aa72f0 | 768 | } |
1da177e4 | 769 | #endif |
13aa72f0 | 770 | |
8112c4f1 | 771 | int __secure_computing(const struct seccomp_data *sd) |
13aa72f0 AL |
772 | { |
773 | int mode = current->seccomp.mode; | |
8112c4f1 | 774 | int this_syscall; |
13aa72f0 | 775 | |
97f2645f | 776 | if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && |
13c4a901 | 777 | unlikely(current->ptrace & PT_SUSPEND_SECCOMP)) |
8112c4f1 KC |
778 | return 0; |
779 | ||
780 | this_syscall = sd ? sd->nr : | |
781 | syscall_get_nr(current, task_pt_regs(current)); | |
13c4a901 | 782 | |
13aa72f0 | 783 | switch (mode) { |
e2cfabdf | 784 | case SECCOMP_MODE_STRICT: |
13aa72f0 | 785 | __secure_computing_strict(this_syscall); /* may call do_exit */ |
8112c4f1 | 786 | return 0; |
13aa72f0 | 787 | case SECCOMP_MODE_FILTER: |
ce6526e8 | 788 | return __seccomp_filter(this_syscall, sd, false); |
1da177e4 LT |
789 | default: |
790 | BUG(); | |
791 | } | |
13aa72f0 | 792 | } |
a4412fc9 | 793 | #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */ |
1d9d02fe AA |
794 | |
795 | long prctl_get_seccomp(void) | |
796 | { | |
797 | return current->seccomp.mode; | |
798 | } | |
799 | ||
e2cfabdf | 800 | /** |
3b23dd12 | 801 | * seccomp_set_mode_strict: internal function for setting strict seccomp |
e2cfabdf WD |
802 | * |
803 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
804 | * | |
805 | * Returns 0 on success or -EINVAL on failure. | |
806 | */ | |
3b23dd12 | 807 | static long seccomp_set_mode_strict(void) |
1d9d02fe | 808 | { |
3b23dd12 | 809 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT; |
e2cfabdf | 810 | long ret = -EINVAL; |
1d9d02fe | 811 | |
dbd95212 KC |
812 | spin_lock_irq(¤t->sighand->siglock); |
813 | ||
1f41b450 | 814 | if (!seccomp_may_assign_mode(seccomp_mode)) |
1d9d02fe AA |
815 | goto out; |
816 | ||
cf99abac | 817 | #ifdef TIF_NOTSC |
3b23dd12 | 818 | disable_TSC(); |
cf99abac | 819 | #endif |
3ba2530c | 820 | seccomp_assign_mode(current, seccomp_mode); |
3b23dd12 KC |
821 | ret = 0; |
822 | ||
823 | out: | |
dbd95212 | 824 | spin_unlock_irq(¤t->sighand->siglock); |
3b23dd12 KC |
825 | |
826 | return ret; | |
827 | } | |
828 | ||
e2cfabdf | 829 | #ifdef CONFIG_SECCOMP_FILTER |
3b23dd12 KC |
830 | /** |
831 | * seccomp_set_mode_filter: internal function for setting seccomp filter | |
48dc92b9 | 832 | * @flags: flags to change filter behavior |
3b23dd12 KC |
833 | * @filter: struct sock_fprog containing filter |
834 | * | |
835 | * This function may be called repeatedly to install additional filters. | |
836 | * Every filter successfully installed will be evaluated (in reverse order) | |
837 | * for each system call the task makes. | |
838 | * | |
839 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
840 | * | |
841 | * Returns 0 on success or -EINVAL on failure. | |
842 | */ | |
48dc92b9 KC |
843 | static long seccomp_set_mode_filter(unsigned int flags, |
844 | const char __user *filter) | |
3b23dd12 KC |
845 | { |
846 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; | |
c8bee430 | 847 | struct seccomp_filter *prepared = NULL; |
3b23dd12 KC |
848 | long ret = -EINVAL; |
849 | ||
48dc92b9 | 850 | /* Validate flags. */ |
c2e1f2e3 | 851 | if (flags & ~SECCOMP_FILTER_FLAG_MASK) |
dbd95212 | 852 | return -EINVAL; |
48dc92b9 | 853 | |
c8bee430 KC |
854 | /* Prepare the new filter before holding any locks. */ |
855 | prepared = seccomp_prepare_user_filter(filter); | |
856 | if (IS_ERR(prepared)) | |
857 | return PTR_ERR(prepared); | |
858 | ||
c2e1f2e3 KC |
859 | /* |
860 | * Make sure we cannot change seccomp or nnp state via TSYNC | |
861 | * while another thread is in the middle of calling exec. | |
862 | */ | |
863 | if (flags & SECCOMP_FILTER_FLAG_TSYNC && | |
864 | mutex_lock_killable(¤t->signal->cred_guard_mutex)) | |
865 | goto out_free; | |
866 | ||
dbd95212 KC |
867 | spin_lock_irq(¤t->sighand->siglock); |
868 | ||
3b23dd12 KC |
869 | if (!seccomp_may_assign_mode(seccomp_mode)) |
870 | goto out; | |
871 | ||
c8bee430 | 872 | ret = seccomp_attach_filter(flags, prepared); |
3b23dd12 | 873 | if (ret) |
e2cfabdf | 874 | goto out; |
c8bee430 KC |
875 | /* Do not free the successfully attached filter. */ |
876 | prepared = NULL; | |
1d9d02fe | 877 | |
3ba2530c | 878 | seccomp_assign_mode(current, seccomp_mode); |
e2cfabdf | 879 | out: |
dbd95212 | 880 | spin_unlock_irq(¤t->sighand->siglock); |
c2e1f2e3 KC |
881 | if (flags & SECCOMP_FILTER_FLAG_TSYNC) |
882 | mutex_unlock(¤t->signal->cred_guard_mutex); | |
883 | out_free: | |
c8bee430 | 884 | seccomp_filter_free(prepared); |
1d9d02fe AA |
885 | return ret; |
886 | } | |
3b23dd12 | 887 | #else |
48dc92b9 KC |
888 | static inline long seccomp_set_mode_filter(unsigned int flags, |
889 | const char __user *filter) | |
3b23dd12 KC |
890 | { |
891 | return -EINVAL; | |
892 | } | |
893 | #endif | |
d78ab02c | 894 | |
d612b1fd TH |
895 | static long seccomp_get_action_avail(const char __user *uaction) |
896 | { | |
897 | u32 action; | |
898 | ||
899 | if (copy_from_user(&action, uaction, sizeof(action))) | |
900 | return -EFAULT; | |
901 | ||
902 | switch (action) { | |
0466bdb9 | 903 | case SECCOMP_RET_KILL_PROCESS: |
fd76875c | 904 | case SECCOMP_RET_KILL_THREAD: |
d612b1fd TH |
905 | case SECCOMP_RET_TRAP: |
906 | case SECCOMP_RET_ERRNO: | |
907 | case SECCOMP_RET_TRACE: | |
59f5cf44 | 908 | case SECCOMP_RET_LOG: |
d612b1fd TH |
909 | case SECCOMP_RET_ALLOW: |
910 | break; | |
911 | default: | |
912 | return -EOPNOTSUPP; | |
913 | } | |
914 | ||
915 | return 0; | |
916 | } | |
917 | ||
48dc92b9 KC |
918 | /* Common entry point for both prctl and syscall. */ |
919 | static long do_seccomp(unsigned int op, unsigned int flags, | |
920 | const char __user *uargs) | |
921 | { | |
922 | switch (op) { | |
923 | case SECCOMP_SET_MODE_STRICT: | |
924 | if (flags != 0 || uargs != NULL) | |
925 | return -EINVAL; | |
926 | return seccomp_set_mode_strict(); | |
927 | case SECCOMP_SET_MODE_FILTER: | |
928 | return seccomp_set_mode_filter(flags, uargs); | |
d612b1fd TH |
929 | case SECCOMP_GET_ACTION_AVAIL: |
930 | if (flags != 0) | |
931 | return -EINVAL; | |
932 | ||
933 | return seccomp_get_action_avail(uargs); | |
48dc92b9 KC |
934 | default: |
935 | return -EINVAL; | |
936 | } | |
937 | } | |
938 | ||
939 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, | |
940 | const char __user *, uargs) | |
941 | { | |
942 | return do_seccomp(op, flags, uargs); | |
943 | } | |
944 | ||
d78ab02c KC |
945 | /** |
946 | * prctl_set_seccomp: configures current->seccomp.mode | |
947 | * @seccomp_mode: requested mode to use | |
948 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER | |
949 | * | |
950 | * Returns 0 on success or -EINVAL on failure. | |
951 | */ | |
952 | long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) | |
953 | { | |
48dc92b9 KC |
954 | unsigned int op; |
955 | char __user *uargs; | |
956 | ||
3b23dd12 KC |
957 | switch (seccomp_mode) { |
958 | case SECCOMP_MODE_STRICT: | |
48dc92b9 KC |
959 | op = SECCOMP_SET_MODE_STRICT; |
960 | /* | |
961 | * Setting strict mode through prctl always ignored filter, | |
962 | * so make sure it is always NULL here to pass the internal | |
963 | * check in do_seccomp(). | |
964 | */ | |
965 | uargs = NULL; | |
966 | break; | |
3b23dd12 | 967 | case SECCOMP_MODE_FILTER: |
48dc92b9 KC |
968 | op = SECCOMP_SET_MODE_FILTER; |
969 | uargs = filter; | |
970 | break; | |
3b23dd12 KC |
971 | default: |
972 | return -EINVAL; | |
973 | } | |
48dc92b9 KC |
974 | |
975 | /* prctl interface doesn't have flags, so they are always zero. */ | |
976 | return do_seccomp(op, 0, uargs); | |
d78ab02c | 977 | } |
f8e529ed TA |
978 | |
979 | #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) | |
980 | long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, | |
981 | void __user *data) | |
982 | { | |
983 | struct seccomp_filter *filter; | |
984 | struct sock_fprog_kern *fprog; | |
985 | long ret; | |
986 | unsigned long count = 0; | |
987 | ||
988 | if (!capable(CAP_SYS_ADMIN) || | |
989 | current->seccomp.mode != SECCOMP_MODE_DISABLED) { | |
990 | return -EACCES; | |
991 | } | |
992 | ||
993 | spin_lock_irq(&task->sighand->siglock); | |
994 | if (task->seccomp.mode != SECCOMP_MODE_FILTER) { | |
995 | ret = -EINVAL; | |
996 | goto out; | |
997 | } | |
998 | ||
999 | filter = task->seccomp.filter; | |
1000 | while (filter) { | |
1001 | filter = filter->prev; | |
1002 | count++; | |
1003 | } | |
1004 | ||
1005 | if (filter_off >= count) { | |
1006 | ret = -ENOENT; | |
1007 | goto out; | |
1008 | } | |
1009 | count -= filter_off; | |
1010 | ||
1011 | filter = task->seccomp.filter; | |
1012 | while (filter && count > 1) { | |
1013 | filter = filter->prev; | |
1014 | count--; | |
1015 | } | |
1016 | ||
1017 | if (WARN_ON(count != 1 || !filter)) { | |
1018 | /* The filter tree shouldn't shrink while we're using it. */ | |
1019 | ret = -ENOENT; | |
1020 | goto out; | |
1021 | } | |
1022 | ||
1023 | fprog = filter->prog->orig_prog; | |
1024 | if (!fprog) { | |
470bf1f2 | 1025 | /* This must be a new non-cBPF filter, since we save |
f8e529ed TA |
1026 | * every cBPF filter's orig_prog above when |
1027 | * CONFIG_CHECKPOINT_RESTORE is enabled. | |
1028 | */ | |
1029 | ret = -EMEDIUMTYPE; | |
1030 | goto out; | |
1031 | } | |
1032 | ||
1033 | ret = fprog->len; | |
1034 | if (!data) | |
1035 | goto out; | |
1036 | ||
66a733ea | 1037 | __get_seccomp_filter(filter); |
f8e529ed TA |
1038 | spin_unlock_irq(&task->sighand->siglock); |
1039 | ||
1040 | if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog))) | |
1041 | ret = -EFAULT; | |
1042 | ||
66a733ea | 1043 | __put_seccomp_filter(filter); |
f8e529ed TA |
1044 | return ret; |
1045 | ||
1046 | out: | |
1047 | spin_unlock_irq(&task->sighand->siglock); | |
1048 | return ret; | |
1049 | } | |
1050 | #endif | |
8e5f1ad1 TH |
1051 | |
1052 | #ifdef CONFIG_SYSCTL | |
1053 | ||
1054 | /* Human readable action names for friendly sysctl interaction */ | |
0466bdb9 | 1055 | #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process" |
fd76875c | 1056 | #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread" |
8e5f1ad1 TH |
1057 | #define SECCOMP_RET_TRAP_NAME "trap" |
1058 | #define SECCOMP_RET_ERRNO_NAME "errno" | |
1059 | #define SECCOMP_RET_TRACE_NAME "trace" | |
59f5cf44 | 1060 | #define SECCOMP_RET_LOG_NAME "log" |
8e5f1ad1 TH |
1061 | #define SECCOMP_RET_ALLOW_NAME "allow" |
1062 | ||
fd76875c | 1063 | static const char seccomp_actions_avail[] = |
0466bdb9 | 1064 | SECCOMP_RET_KILL_PROCESS_NAME " " |
fd76875c KC |
1065 | SECCOMP_RET_KILL_THREAD_NAME " " |
1066 | SECCOMP_RET_TRAP_NAME " " | |
1067 | SECCOMP_RET_ERRNO_NAME " " | |
1068 | SECCOMP_RET_TRACE_NAME " " | |
1069 | SECCOMP_RET_LOG_NAME " " | |
1070 | SECCOMP_RET_ALLOW_NAME; | |
8e5f1ad1 | 1071 | |
0ddec0fc TH |
1072 | struct seccomp_log_name { |
1073 | u32 log; | |
1074 | const char *name; | |
1075 | }; | |
1076 | ||
1077 | static const struct seccomp_log_name seccomp_log_names[] = { | |
0466bdb9 | 1078 | { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME }, |
fd76875c | 1079 | { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME }, |
0ddec0fc TH |
1080 | { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME }, |
1081 | { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME }, | |
1082 | { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME }, | |
59f5cf44 | 1083 | { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME }, |
0ddec0fc TH |
1084 | { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME }, |
1085 | { } | |
1086 | }; | |
1087 | ||
1088 | static bool seccomp_names_from_actions_logged(char *names, size_t size, | |
1089 | u32 actions_logged) | |
1090 | { | |
1091 | const struct seccomp_log_name *cur; | |
1092 | bool append_space = false; | |
1093 | ||
1094 | for (cur = seccomp_log_names; cur->name && size; cur++) { | |
1095 | ssize_t ret; | |
1096 | ||
1097 | if (!(actions_logged & cur->log)) | |
1098 | continue; | |
1099 | ||
1100 | if (append_space) { | |
1101 | ret = strscpy(names, " ", size); | |
1102 | if (ret < 0) | |
1103 | return false; | |
1104 | ||
1105 | names += ret; | |
1106 | size -= ret; | |
1107 | } else | |
1108 | append_space = true; | |
1109 | ||
1110 | ret = strscpy(names, cur->name, size); | |
1111 | if (ret < 0) | |
1112 | return false; | |
1113 | ||
1114 | names += ret; | |
1115 | size -= ret; | |
1116 | } | |
1117 | ||
1118 | return true; | |
1119 | } | |
1120 | ||
1121 | static bool seccomp_action_logged_from_name(u32 *action_logged, | |
1122 | const char *name) | |
1123 | { | |
1124 | const struct seccomp_log_name *cur; | |
1125 | ||
1126 | for (cur = seccomp_log_names; cur->name; cur++) { | |
1127 | if (!strcmp(cur->name, name)) { | |
1128 | *action_logged = cur->log; | |
1129 | return true; | |
1130 | } | |
1131 | } | |
1132 | ||
1133 | return false; | |
1134 | } | |
1135 | ||
1136 | static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names) | |
1137 | { | |
1138 | char *name; | |
1139 | ||
1140 | *actions_logged = 0; | |
1141 | while ((name = strsep(&names, " ")) && *name) { | |
1142 | u32 action_logged = 0; | |
1143 | ||
1144 | if (!seccomp_action_logged_from_name(&action_logged, name)) | |
1145 | return false; | |
1146 | ||
1147 | *actions_logged |= action_logged; | |
1148 | } | |
1149 | ||
1150 | return true; | |
1151 | } | |
1152 | ||
1153 | static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write, | |
1154 | void __user *buffer, size_t *lenp, | |
1155 | loff_t *ppos) | |
1156 | { | |
1157 | char names[sizeof(seccomp_actions_avail)]; | |
1158 | struct ctl_table table; | |
1159 | int ret; | |
1160 | ||
1161 | if (write && !capable(CAP_SYS_ADMIN)) | |
1162 | return -EPERM; | |
1163 | ||
1164 | memset(names, 0, sizeof(names)); | |
1165 | ||
1166 | if (!write) { | |
1167 | if (!seccomp_names_from_actions_logged(names, sizeof(names), | |
1168 | seccomp_actions_logged)) | |
1169 | return -EINVAL; | |
1170 | } | |
1171 | ||
1172 | table = *ro_table; | |
1173 | table.data = names; | |
1174 | table.maxlen = sizeof(names); | |
1175 | ret = proc_dostring(&table, write, buffer, lenp, ppos); | |
1176 | if (ret) | |
1177 | return ret; | |
1178 | ||
1179 | if (write) { | |
1180 | u32 actions_logged; | |
1181 | ||
1182 | if (!seccomp_actions_logged_from_names(&actions_logged, | |
1183 | table.data)) | |
1184 | return -EINVAL; | |
1185 | ||
1186 | if (actions_logged & SECCOMP_LOG_ALLOW) | |
1187 | return -EINVAL; | |
1188 | ||
1189 | seccomp_actions_logged = actions_logged; | |
1190 | } | |
1191 | ||
1192 | return 0; | |
1193 | } | |
1194 | ||
8e5f1ad1 TH |
1195 | static struct ctl_path seccomp_sysctl_path[] = { |
1196 | { .procname = "kernel", }, | |
1197 | { .procname = "seccomp", }, | |
1198 | { } | |
1199 | }; | |
1200 | ||
1201 | static struct ctl_table seccomp_sysctl_table[] = { | |
1202 | { | |
1203 | .procname = "actions_avail", | |
1204 | .data = (void *) &seccomp_actions_avail, | |
1205 | .maxlen = sizeof(seccomp_actions_avail), | |
1206 | .mode = 0444, | |
1207 | .proc_handler = proc_dostring, | |
1208 | }, | |
0ddec0fc TH |
1209 | { |
1210 | .procname = "actions_logged", | |
1211 | .mode = 0644, | |
1212 | .proc_handler = seccomp_actions_logged_handler, | |
1213 | }, | |
8e5f1ad1 TH |
1214 | { } |
1215 | }; | |
1216 | ||
1217 | static int __init seccomp_sysctl_init(void) | |
1218 | { | |
1219 | struct ctl_table_header *hdr; | |
1220 | ||
1221 | hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table); | |
1222 | if (!hdr) | |
1223 | pr_warn("seccomp: sysctl registration failed\n"); | |
1224 | else | |
1225 | kmemleak_not_leak(hdr); | |
1226 | ||
1227 | return 0; | |
1228 | } | |
1229 | ||
1230 | device_initcall(seccomp_sysctl_init) | |
1231 | ||
1232 | #endif /* CONFIG_SYSCTL */ |