Commit | Line | Data |
---|---|---|
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 | ||
e2cfabdf | 16 | #include <linux/atomic.h> |
85e7bac3 | 17 | #include <linux/audit.h> |
5b101740 | 18 | #include <linux/compat.h> |
e2cfabdf WD |
19 | #include <linux/sched.h> |
20 | #include <linux/seccomp.h> | |
c8bee430 | 21 | #include <linux/slab.h> |
48dc92b9 | 22 | #include <linux/syscalls.h> |
1da177e4 LT |
23 | |
24 | /* #define SECCOMP_DEBUG 1 */ | |
e2cfabdf WD |
25 | |
26 | #ifdef CONFIG_SECCOMP_FILTER | |
27 | #include <asm/syscall.h> | |
28 | #include <linux/filter.h> | |
fb0fadf9 | 29 | #include <linux/ptrace.h> |
e2cfabdf | 30 | #include <linux/security.h> |
e2cfabdf WD |
31 | #include <linux/tracehook.h> |
32 | #include <linux/uaccess.h> | |
33 | ||
34 | /** | |
35 | * struct seccomp_filter - container for seccomp BPF programs | |
36 | * | |
37 | * @usage: reference count to manage the object lifetime. | |
38 | * get/put helpers should be used when accessing an instance | |
39 | * outside of a lifetime-guarded section. In general, this | |
40 | * is only needed for handling filters shared across tasks. | |
41 | * @prev: points to a previously installed, or inherited, filter | |
42 | * @len: the number of instructions in the program | |
119ce5c8 | 43 | * @insnsi: the BPF program instructions to evaluate |
e2cfabdf WD |
44 | * |
45 | * seccomp_filter objects are organized in a tree linked via the @prev | |
46 | * pointer. For any task, it appears to be a singly-linked list starting | |
47 | * with current->seccomp.filter, the most recently attached or inherited filter. | |
48 | * However, multiple filters may share a @prev node, by way of fork(), which | |
49 | * results in a unidirectional tree existing in memory. This is similar to | |
50 | * how namespaces work. | |
51 | * | |
52 | * seccomp_filter objects should never be modified after being attached | |
53 | * to a task_struct (other than @usage). | |
54 | */ | |
55 | struct seccomp_filter { | |
56 | atomic_t usage; | |
57 | struct seccomp_filter *prev; | |
8f577cad | 58 | struct sk_filter *prog; |
e2cfabdf WD |
59 | }; |
60 | ||
61 | /* Limit any path through the tree to 256KB worth of instructions. */ | |
62 | #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter)) | |
63 | ||
bd4cf0ed | 64 | /* |
e2cfabdf WD |
65 | * Endianness is explicitly ignored and left for BPF program authors to manage |
66 | * as per the specific architecture. | |
67 | */ | |
bd4cf0ed | 68 | static void populate_seccomp_data(struct seccomp_data *sd) |
e2cfabdf | 69 | { |
bd4cf0ed AS |
70 | struct task_struct *task = current; |
71 | struct pt_regs *regs = task_pt_regs(task); | |
2eac7648 | 72 | unsigned long args[6]; |
e2cfabdf | 73 | |
bd4cf0ed | 74 | sd->nr = syscall_get_nr(task, regs); |
0b747172 | 75 | sd->arch = syscall_get_arch(); |
2eac7648 DB |
76 | syscall_get_arguments(task, regs, 0, 6, args); |
77 | sd->args[0] = args[0]; | |
78 | sd->args[1] = args[1]; | |
79 | sd->args[2] = args[2]; | |
80 | sd->args[3] = args[3]; | |
81 | sd->args[4] = args[4]; | |
82 | sd->args[5] = args[5]; | |
bd4cf0ed | 83 | sd->instruction_pointer = KSTK_EIP(task); |
e2cfabdf WD |
84 | } |
85 | ||
86 | /** | |
87 | * seccomp_check_filter - verify seccomp filter code | |
88 | * @filter: filter to verify | |
89 | * @flen: length of filter | |
90 | * | |
91 | * Takes a previously checked filter (by sk_chk_filter) and | |
92 | * redirects all filter code that loads struct sk_buff data | |
93 | * and related data through seccomp_bpf_load. It also | |
94 | * enforces length and alignment checking of those loads. | |
95 | * | |
96 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
97 | */ | |
98 | static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen) | |
99 | { | |
100 | int pc; | |
101 | for (pc = 0; pc < flen; pc++) { | |
102 | struct sock_filter *ftest = &filter[pc]; | |
103 | u16 code = ftest->code; | |
104 | u32 k = ftest->k; | |
105 | ||
106 | switch (code) { | |
34805931 | 107 | case BPF_LD | BPF_W | BPF_ABS: |
bd4cf0ed | 108 | ftest->code = BPF_LDX | BPF_W | BPF_ABS; |
e2cfabdf WD |
109 | /* 32-bit aligned and not out of bounds. */ |
110 | if (k >= sizeof(struct seccomp_data) || k & 3) | |
111 | return -EINVAL; | |
112 | continue; | |
34805931 | 113 | case BPF_LD | BPF_W | BPF_LEN: |
bd4cf0ed | 114 | ftest->code = BPF_LD | BPF_IMM; |
e2cfabdf WD |
115 | ftest->k = sizeof(struct seccomp_data); |
116 | continue; | |
34805931 | 117 | case BPF_LDX | BPF_W | BPF_LEN: |
bd4cf0ed | 118 | ftest->code = BPF_LDX | BPF_IMM; |
e2cfabdf WD |
119 | ftest->k = sizeof(struct seccomp_data); |
120 | continue; | |
121 | /* Explicitly include allowed calls. */ | |
34805931 DB |
122 | case BPF_RET | BPF_K: |
123 | case BPF_RET | BPF_A: | |
124 | case BPF_ALU | BPF_ADD | BPF_K: | |
125 | case BPF_ALU | BPF_ADD | BPF_X: | |
126 | case BPF_ALU | BPF_SUB | BPF_K: | |
127 | case BPF_ALU | BPF_SUB | BPF_X: | |
128 | case BPF_ALU | BPF_MUL | BPF_K: | |
129 | case BPF_ALU | BPF_MUL | BPF_X: | |
130 | case BPF_ALU | BPF_DIV | BPF_K: | |
131 | case BPF_ALU | BPF_DIV | BPF_X: | |
132 | case BPF_ALU | BPF_AND | BPF_K: | |
133 | case BPF_ALU | BPF_AND | BPF_X: | |
134 | case BPF_ALU | BPF_OR | BPF_K: | |
135 | case BPF_ALU | BPF_OR | BPF_X: | |
136 | case BPF_ALU | BPF_XOR | BPF_K: | |
137 | case BPF_ALU | BPF_XOR | BPF_X: | |
138 | case BPF_ALU | BPF_LSH | BPF_K: | |
139 | case BPF_ALU | BPF_LSH | BPF_X: | |
140 | case BPF_ALU | BPF_RSH | BPF_K: | |
141 | case BPF_ALU | BPF_RSH | BPF_X: | |
142 | case BPF_ALU | BPF_NEG: | |
143 | case BPF_LD | BPF_IMM: | |
144 | case BPF_LDX | BPF_IMM: | |
145 | case BPF_MISC | BPF_TAX: | |
146 | case BPF_MISC | BPF_TXA: | |
147 | case BPF_LD | BPF_MEM: | |
148 | case BPF_LDX | BPF_MEM: | |
149 | case BPF_ST: | |
150 | case BPF_STX: | |
151 | case BPF_JMP | BPF_JA: | |
152 | case BPF_JMP | BPF_JEQ | BPF_K: | |
153 | case BPF_JMP | BPF_JEQ | BPF_X: | |
154 | case BPF_JMP | BPF_JGE | BPF_K: | |
155 | case BPF_JMP | BPF_JGE | BPF_X: | |
156 | case BPF_JMP | BPF_JGT | BPF_K: | |
157 | case BPF_JMP | BPF_JGT | BPF_X: | |
158 | case BPF_JMP | BPF_JSET | BPF_K: | |
159 | case BPF_JMP | BPF_JSET | BPF_X: | |
e2cfabdf WD |
160 | continue; |
161 | default: | |
162 | return -EINVAL; | |
163 | } | |
164 | } | |
165 | return 0; | |
166 | } | |
167 | ||
168 | /** | |
169 | * seccomp_run_filters - evaluates all seccomp filters against @syscall | |
170 | * @syscall: number of the current system call | |
171 | * | |
172 | * Returns valid seccomp BPF response codes. | |
173 | */ | |
174 | static u32 seccomp_run_filters(int syscall) | |
175 | { | |
176 | struct seccomp_filter *f; | |
bd4cf0ed | 177 | struct seccomp_data sd; |
acf3b2c7 WD |
178 | u32 ret = SECCOMP_RET_ALLOW; |
179 | ||
180 | /* Ensure unexpected behavior doesn't result in failing open. */ | |
181 | if (WARN_ON(current->seccomp.filter == NULL)) | |
182 | return SECCOMP_RET_KILL; | |
183 | ||
bd4cf0ed AS |
184 | populate_seccomp_data(&sd); |
185 | ||
e2cfabdf WD |
186 | /* |
187 | * All filters in the list are evaluated and the lowest BPF return | |
acf3b2c7 | 188 | * value always takes priority (ignoring the DATA). |
e2cfabdf WD |
189 | */ |
190 | for (f = current->seccomp.filter; f; f = f->prev) { | |
8f577cad AS |
191 | u32 cur_ret = SK_RUN_FILTER(f->prog, (void *)&sd); |
192 | ||
acf3b2c7 WD |
193 | if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION)) |
194 | ret = cur_ret; | |
e2cfabdf WD |
195 | } |
196 | return ret; | |
197 | } | |
1f41b450 | 198 | #endif /* CONFIG_SECCOMP_FILTER */ |
e2cfabdf | 199 | |
1f41b450 KC |
200 | static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode) |
201 | { | |
202 | if (current->seccomp.mode && current->seccomp.mode != seccomp_mode) | |
203 | return false; | |
204 | ||
205 | return true; | |
206 | } | |
207 | ||
208 | static inline void seccomp_assign_mode(unsigned long seccomp_mode) | |
209 | { | |
210 | current->seccomp.mode = seccomp_mode; | |
211 | set_tsk_thread_flag(current, TIF_SECCOMP); | |
212 | } | |
213 | ||
214 | #ifdef CONFIG_SECCOMP_FILTER | |
e2cfabdf | 215 | /** |
c8bee430 | 216 | * seccomp_prepare_filter: Prepares a seccomp filter for use. |
e2cfabdf WD |
217 | * @fprog: BPF program to install |
218 | * | |
c8bee430 | 219 | * Returns filter on success or an ERR_PTR on failure. |
e2cfabdf | 220 | */ |
c8bee430 | 221 | static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) |
e2cfabdf WD |
222 | { |
223 | struct seccomp_filter *filter; | |
c8bee430 | 224 | unsigned long fp_size; |
bd4cf0ed AS |
225 | struct sock_filter *fp; |
226 | int new_len; | |
e2cfabdf WD |
227 | long ret; |
228 | ||
229 | if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) | |
c8bee430 KC |
230 | return ERR_PTR(-EINVAL); |
231 | BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); | |
232 | fp_size = fprog->len * sizeof(struct sock_filter); | |
e2cfabdf WD |
233 | |
234 | /* | |
119ce5c8 | 235 | * Installing a seccomp filter requires that the task has |
e2cfabdf WD |
236 | * CAP_SYS_ADMIN in its namespace or be running with no_new_privs. |
237 | * This avoids scenarios where unprivileged tasks can affect the | |
238 | * behavior of privileged children. | |
239 | */ | |
1d4457f9 | 240 | if (!task_no_new_privs(current) && |
e2cfabdf WD |
241 | security_capable_noaudit(current_cred(), current_user_ns(), |
242 | CAP_SYS_ADMIN) != 0) | |
c8bee430 | 243 | return ERR_PTR(-EACCES); |
e2cfabdf | 244 | |
bd4cf0ed AS |
245 | fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN); |
246 | if (!fp) | |
c8bee430 | 247 | return ERR_PTR(-ENOMEM); |
e2cfabdf WD |
248 | |
249 | /* Copy the instructions from fprog. */ | |
250 | ret = -EFAULT; | |
bd4cf0ed AS |
251 | if (copy_from_user(fp, fprog->filter, fp_size)) |
252 | goto free_prog; | |
e2cfabdf WD |
253 | |
254 | /* Check and rewrite the fprog via the skb checker */ | |
bd4cf0ed | 255 | ret = sk_chk_filter(fp, fprog->len); |
e2cfabdf | 256 | if (ret) |
bd4cf0ed | 257 | goto free_prog; |
e2cfabdf WD |
258 | |
259 | /* Check and rewrite the fprog for seccomp use */ | |
bd4cf0ed AS |
260 | ret = seccomp_check_filter(fp, fprog->len); |
261 | if (ret) | |
262 | goto free_prog; | |
263 | ||
264 | /* Convert 'sock_filter' insns to 'sock_filter_int' insns */ | |
265 | ret = sk_convert_filter(fp, fprog->len, NULL, &new_len); | |
266 | if (ret) | |
267 | goto free_prog; | |
268 | ||
269 | /* Allocate a new seccomp_filter */ | |
0acf07d2 | 270 | ret = -ENOMEM; |
8f577cad | 271 | filter = kzalloc(sizeof(struct seccomp_filter), |
bd4cf0ed AS |
272 | GFP_KERNEL|__GFP_NOWARN); |
273 | if (!filter) | |
274 | goto free_prog; | |
275 | ||
8f577cad AS |
276 | filter->prog = kzalloc(sk_filter_size(new_len), |
277 | GFP_KERNEL|__GFP_NOWARN); | |
278 | if (!filter->prog) | |
bd4cf0ed | 279 | goto free_filter; |
8f577cad AS |
280 | |
281 | ret = sk_convert_filter(fp, fprog->len, filter->prog->insnsi, &new_len); | |
282 | if (ret) | |
283 | goto free_filter_prog; | |
0acf07d2 | 284 | kfree(fp); |
bd4cf0ed AS |
285 | |
286 | atomic_set(&filter->usage, 1); | |
8f577cad | 287 | filter->prog->len = new_len; |
8f577cad | 288 | |
5fe821a9 | 289 | sk_filter_select_runtime(filter->prog); |
e2cfabdf | 290 | |
c8bee430 | 291 | return filter; |
bd4cf0ed | 292 | |
8f577cad AS |
293 | free_filter_prog: |
294 | kfree(filter->prog); | |
bd4cf0ed | 295 | free_filter: |
e2cfabdf | 296 | kfree(filter); |
bd4cf0ed AS |
297 | free_prog: |
298 | kfree(fp); | |
c8bee430 | 299 | return ERR_PTR(ret); |
e2cfabdf WD |
300 | } |
301 | ||
302 | /** | |
c8bee430 | 303 | * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog |
e2cfabdf WD |
304 | * @user_filter: pointer to the user data containing a sock_fprog. |
305 | * | |
306 | * Returns 0 on success and non-zero otherwise. | |
307 | */ | |
c8bee430 KC |
308 | static struct seccomp_filter * |
309 | seccomp_prepare_user_filter(const char __user *user_filter) | |
e2cfabdf WD |
310 | { |
311 | struct sock_fprog fprog; | |
c8bee430 | 312 | struct seccomp_filter *filter = ERR_PTR(-EFAULT); |
e2cfabdf WD |
313 | |
314 | #ifdef CONFIG_COMPAT | |
315 | if (is_compat_task()) { | |
316 | struct compat_sock_fprog fprog32; | |
317 | if (copy_from_user(&fprog32, user_filter, sizeof(fprog32))) | |
318 | goto out; | |
319 | fprog.len = fprog32.len; | |
320 | fprog.filter = compat_ptr(fprog32.filter); | |
321 | } else /* falls through to the if below. */ | |
322 | #endif | |
323 | if (copy_from_user(&fprog, user_filter, sizeof(fprog))) | |
324 | goto out; | |
c8bee430 | 325 | filter = seccomp_prepare_filter(&fprog); |
e2cfabdf | 326 | out: |
c8bee430 KC |
327 | return filter; |
328 | } | |
329 | ||
330 | /** | |
331 | * seccomp_attach_filter: validate and attach filter | |
332 | * @flags: flags to change filter behavior | |
333 | * @filter: seccomp filter to add to the current process | |
334 | * | |
335 | * Returns 0 on success, -ve on error. | |
336 | */ | |
337 | static long seccomp_attach_filter(unsigned int flags, | |
338 | struct seccomp_filter *filter) | |
339 | { | |
340 | unsigned long total_insns; | |
341 | struct seccomp_filter *walker; | |
342 | ||
343 | /* Validate resulting filter length. */ | |
344 | total_insns = filter->prog->len; | |
345 | for (walker = current->seccomp.filter; walker; walker = walker->prev) | |
346 | total_insns += walker->prog->len + 4; /* 4 instr penalty */ | |
347 | if (total_insns > MAX_INSNS_PER_PATH) | |
348 | return -ENOMEM; | |
349 | ||
350 | /* | |
351 | * If there is an existing filter, make it the prev and don't drop its | |
352 | * task reference. | |
353 | */ | |
354 | filter->prev = current->seccomp.filter; | |
355 | current->seccomp.filter = filter; | |
356 | ||
357 | return 0; | |
e2cfabdf WD |
358 | } |
359 | ||
360 | /* get_seccomp_filter - increments the reference count of the filter on @tsk */ | |
361 | void get_seccomp_filter(struct task_struct *tsk) | |
362 | { | |
363 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
364 | if (!orig) | |
365 | return; | |
366 | /* Reference count is bounded by the number of total processes. */ | |
367 | atomic_inc(&orig->usage); | |
368 | } | |
369 | ||
c8bee430 KC |
370 | static inline void seccomp_filter_free(struct seccomp_filter *filter) |
371 | { | |
372 | if (filter) { | |
373 | sk_filter_free(filter->prog); | |
374 | kfree(filter); | |
375 | } | |
376 | } | |
377 | ||
e2cfabdf WD |
378 | /* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */ |
379 | void put_seccomp_filter(struct task_struct *tsk) | |
380 | { | |
381 | struct seccomp_filter *orig = tsk->seccomp.filter; | |
382 | /* Clean up single-reference branches iteratively. */ | |
383 | while (orig && atomic_dec_and_test(&orig->usage)) { | |
384 | struct seccomp_filter *freeme = orig; | |
385 | orig = orig->prev; | |
c8bee430 | 386 | seccomp_filter_free(freeme); |
e2cfabdf WD |
387 | } |
388 | } | |
bb6ea430 WD |
389 | |
390 | /** | |
391 | * seccomp_send_sigsys - signals the task to allow in-process syscall emulation | |
392 | * @syscall: syscall number to send to userland | |
393 | * @reason: filter-supplied reason code to send to userland (via si_errno) | |
394 | * | |
395 | * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. | |
396 | */ | |
397 | static void seccomp_send_sigsys(int syscall, int reason) | |
398 | { | |
399 | struct siginfo info; | |
400 | memset(&info, 0, sizeof(info)); | |
401 | info.si_signo = SIGSYS; | |
402 | info.si_code = SYS_SECCOMP; | |
403 | info.si_call_addr = (void __user *)KSTK_EIP(current); | |
404 | info.si_errno = reason; | |
5e937a9a | 405 | info.si_arch = syscall_get_arch(); |
bb6ea430 WD |
406 | info.si_syscall = syscall; |
407 | force_sig_info(SIGSYS, &info, current); | |
408 | } | |
e2cfabdf | 409 | #endif /* CONFIG_SECCOMP_FILTER */ |
1da177e4 LT |
410 | |
411 | /* | |
412 | * Secure computing mode 1 allows only read/write/exit/sigreturn. | |
413 | * To be fully secure this must be combined with rlimit | |
414 | * to limit the stack allocations too. | |
415 | */ | |
416 | static int mode1_syscalls[] = { | |
417 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, | |
418 | 0, /* null terminated */ | |
419 | }; | |
420 | ||
5b101740 | 421 | #ifdef CONFIG_COMPAT |
1da177e4 LT |
422 | static int mode1_syscalls_32[] = { |
423 | __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32, | |
424 | 0, /* null terminated */ | |
425 | }; | |
426 | #endif | |
427 | ||
acf3b2c7 | 428 | int __secure_computing(int this_syscall) |
1da177e4 LT |
429 | { |
430 | int mode = current->seccomp.mode; | |
e2cfabdf WD |
431 | int exit_sig = 0; |
432 | int *syscall; | |
8156b451 | 433 | u32 ret; |
1da177e4 LT |
434 | |
435 | switch (mode) { | |
e2cfabdf | 436 | case SECCOMP_MODE_STRICT: |
1da177e4 | 437 | syscall = mode1_syscalls; |
5b101740 RM |
438 | #ifdef CONFIG_COMPAT |
439 | if (is_compat_task()) | |
1da177e4 LT |
440 | syscall = mode1_syscalls_32; |
441 | #endif | |
442 | do { | |
443 | if (*syscall == this_syscall) | |
acf3b2c7 | 444 | return 0; |
1da177e4 | 445 | } while (*++syscall); |
e2cfabdf | 446 | exit_sig = SIGKILL; |
8156b451 | 447 | ret = SECCOMP_RET_KILL; |
1da177e4 | 448 | break; |
e2cfabdf | 449 | #ifdef CONFIG_SECCOMP_FILTER |
8156b451 WD |
450 | case SECCOMP_MODE_FILTER: { |
451 | int data; | |
87b526d3 | 452 | struct pt_regs *regs = task_pt_regs(current); |
acf3b2c7 WD |
453 | ret = seccomp_run_filters(this_syscall); |
454 | data = ret & SECCOMP_RET_DATA; | |
8156b451 WD |
455 | ret &= SECCOMP_RET_ACTION; |
456 | switch (ret) { | |
acf3b2c7 WD |
457 | case SECCOMP_RET_ERRNO: |
458 | /* Set the low-order 16-bits as a errno. */ | |
87b526d3 | 459 | syscall_set_return_value(current, regs, |
acf3b2c7 WD |
460 | -data, 0); |
461 | goto skip; | |
bb6ea430 WD |
462 | case SECCOMP_RET_TRAP: |
463 | /* Show the handler the original registers. */ | |
87b526d3 | 464 | syscall_rollback(current, regs); |
bb6ea430 WD |
465 | /* Let the filter pass back 16 bits of data. */ |
466 | seccomp_send_sigsys(this_syscall, data); | |
467 | goto skip; | |
fb0fadf9 WD |
468 | case SECCOMP_RET_TRACE: |
469 | /* Skip these calls if there is no tracer. */ | |
87b526d3 AL |
470 | if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { |
471 | syscall_set_return_value(current, regs, | |
472 | -ENOSYS, 0); | |
fb0fadf9 | 473 | goto skip; |
87b526d3 | 474 | } |
fb0fadf9 WD |
475 | /* Allow the BPF to provide the event message */ |
476 | ptrace_event(PTRACE_EVENT_SECCOMP, data); | |
477 | /* | |
478 | * The delivery of a fatal signal during event | |
479 | * notification may silently skip tracer notification. | |
480 | * Terminating the task now avoids executing a system | |
481 | * call that may not be intended. | |
482 | */ | |
483 | if (fatal_signal_pending(current)) | |
484 | break; | |
87b526d3 AL |
485 | if (syscall_get_nr(current, regs) < 0) |
486 | goto skip; /* Explicit request to skip. */ | |
487 | ||
fb0fadf9 | 488 | return 0; |
acf3b2c7 WD |
489 | case SECCOMP_RET_ALLOW: |
490 | return 0; | |
491 | case SECCOMP_RET_KILL: | |
492 | default: | |
493 | break; | |
494 | } | |
e2cfabdf WD |
495 | exit_sig = SIGSYS; |
496 | break; | |
8156b451 | 497 | } |
e2cfabdf | 498 | #endif |
1da177e4 LT |
499 | default: |
500 | BUG(); | |
501 | } | |
502 | ||
503 | #ifdef SECCOMP_DEBUG | |
504 | dump_stack(); | |
505 | #endif | |
acf3b2c7 | 506 | audit_seccomp(this_syscall, exit_sig, ret); |
e2cfabdf | 507 | do_exit(exit_sig); |
8156b451 | 508 | #ifdef CONFIG_SECCOMP_FILTER |
acf3b2c7 WD |
509 | skip: |
510 | audit_seccomp(this_syscall, exit_sig, ret); | |
8156b451 | 511 | #endif |
acf3b2c7 | 512 | return -1; |
1da177e4 | 513 | } |
1d9d02fe AA |
514 | |
515 | long prctl_get_seccomp(void) | |
516 | { | |
517 | return current->seccomp.mode; | |
518 | } | |
519 | ||
e2cfabdf | 520 | /** |
3b23dd12 | 521 | * seccomp_set_mode_strict: internal function for setting strict seccomp |
e2cfabdf WD |
522 | * |
523 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
524 | * | |
525 | * Returns 0 on success or -EINVAL on failure. | |
526 | */ | |
3b23dd12 | 527 | static long seccomp_set_mode_strict(void) |
1d9d02fe | 528 | { |
3b23dd12 | 529 | const unsigned long seccomp_mode = SECCOMP_MODE_STRICT; |
e2cfabdf | 530 | long ret = -EINVAL; |
1d9d02fe | 531 | |
1f41b450 | 532 | if (!seccomp_may_assign_mode(seccomp_mode)) |
1d9d02fe AA |
533 | goto out; |
534 | ||
cf99abac | 535 | #ifdef TIF_NOTSC |
3b23dd12 | 536 | disable_TSC(); |
cf99abac | 537 | #endif |
3b23dd12 KC |
538 | seccomp_assign_mode(seccomp_mode); |
539 | ret = 0; | |
540 | ||
541 | out: | |
542 | ||
543 | return ret; | |
544 | } | |
545 | ||
e2cfabdf | 546 | #ifdef CONFIG_SECCOMP_FILTER |
3b23dd12 KC |
547 | /** |
548 | * seccomp_set_mode_filter: internal function for setting seccomp filter | |
48dc92b9 | 549 | * @flags: flags to change filter behavior |
3b23dd12 KC |
550 | * @filter: struct sock_fprog containing filter |
551 | * | |
552 | * This function may be called repeatedly to install additional filters. | |
553 | * Every filter successfully installed will be evaluated (in reverse order) | |
554 | * for each system call the task makes. | |
555 | * | |
556 | * Once current->seccomp.mode is non-zero, it may not be changed. | |
557 | * | |
558 | * Returns 0 on success or -EINVAL on failure. | |
559 | */ | |
48dc92b9 KC |
560 | static long seccomp_set_mode_filter(unsigned int flags, |
561 | const char __user *filter) | |
3b23dd12 KC |
562 | { |
563 | const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; | |
c8bee430 | 564 | struct seccomp_filter *prepared = NULL; |
3b23dd12 KC |
565 | long ret = -EINVAL; |
566 | ||
48dc92b9 KC |
567 | /* Validate flags. */ |
568 | if (flags != 0) | |
569 | goto out; | |
570 | ||
c8bee430 KC |
571 | /* Prepare the new filter before holding any locks. */ |
572 | prepared = seccomp_prepare_user_filter(filter); | |
573 | if (IS_ERR(prepared)) | |
574 | return PTR_ERR(prepared); | |
575 | ||
3b23dd12 KC |
576 | if (!seccomp_may_assign_mode(seccomp_mode)) |
577 | goto out; | |
578 | ||
c8bee430 | 579 | ret = seccomp_attach_filter(flags, prepared); |
3b23dd12 | 580 | if (ret) |
e2cfabdf | 581 | goto out; |
c8bee430 KC |
582 | /* Do not free the successfully attached filter. */ |
583 | prepared = NULL; | |
1d9d02fe | 584 | |
1f41b450 | 585 | seccomp_assign_mode(seccomp_mode); |
e2cfabdf | 586 | out: |
c8bee430 | 587 | seccomp_filter_free(prepared); |
1d9d02fe AA |
588 | return ret; |
589 | } | |
3b23dd12 | 590 | #else |
48dc92b9 KC |
591 | static inline long seccomp_set_mode_filter(unsigned int flags, |
592 | const char __user *filter) | |
3b23dd12 KC |
593 | { |
594 | return -EINVAL; | |
595 | } | |
596 | #endif | |
d78ab02c | 597 | |
48dc92b9 KC |
598 | /* Common entry point for both prctl and syscall. */ |
599 | static long do_seccomp(unsigned int op, unsigned int flags, | |
600 | const char __user *uargs) | |
601 | { | |
602 | switch (op) { | |
603 | case SECCOMP_SET_MODE_STRICT: | |
604 | if (flags != 0 || uargs != NULL) | |
605 | return -EINVAL; | |
606 | return seccomp_set_mode_strict(); | |
607 | case SECCOMP_SET_MODE_FILTER: | |
608 | return seccomp_set_mode_filter(flags, uargs); | |
609 | default: | |
610 | return -EINVAL; | |
611 | } | |
612 | } | |
613 | ||
614 | SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, | |
615 | const char __user *, uargs) | |
616 | { | |
617 | return do_seccomp(op, flags, uargs); | |
618 | } | |
619 | ||
d78ab02c KC |
620 | /** |
621 | * prctl_set_seccomp: configures current->seccomp.mode | |
622 | * @seccomp_mode: requested mode to use | |
623 | * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER | |
624 | * | |
625 | * Returns 0 on success or -EINVAL on failure. | |
626 | */ | |
627 | long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) | |
628 | { | |
48dc92b9 KC |
629 | unsigned int op; |
630 | char __user *uargs; | |
631 | ||
3b23dd12 KC |
632 | switch (seccomp_mode) { |
633 | case SECCOMP_MODE_STRICT: | |
48dc92b9 KC |
634 | op = SECCOMP_SET_MODE_STRICT; |
635 | /* | |
636 | * Setting strict mode through prctl always ignored filter, | |
637 | * so make sure it is always NULL here to pass the internal | |
638 | * check in do_seccomp(). | |
639 | */ | |
640 | uargs = NULL; | |
641 | break; | |
3b23dd12 | 642 | case SECCOMP_MODE_FILTER: |
48dc92b9 KC |
643 | op = SECCOMP_SET_MODE_FILTER; |
644 | uargs = filter; | |
645 | break; | |
3b23dd12 KC |
646 | default: |
647 | return -EINVAL; | |
648 | } | |
48dc92b9 KC |
649 | |
650 | /* prctl interface doesn't have flags, so they are always zero. */ | |
651 | return do_seccomp(op, 0, uargs); | |
d78ab02c | 652 | } |