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1 | /** |
2 | * Seccomp Library API | |
3 | * | |
4 | * Copyright (c) 2012,2013 Red Hat <pmoore@redhat.com> | |
5 | * Author: Paul Moore <paul@paul-moore.com> | |
6 | */ | |
7 | ||
8 | /* | |
9 | * This library is free software; you can redistribute it and/or modify it | |
10 | * under the terms of version 2.1 of the GNU Lesser General Public License as | |
11 | * published by the Free Software Foundation. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, but WITHOUT | |
14 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License | |
16 | * for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public License | |
19 | * along with this library; if not, see <http://www.gnu.org/licenses>. | |
20 | */ | |
21 | ||
22 | #include <endian.h> | |
23 | #include <errno.h> | |
24 | #include <inttypes.h> | |
25 | #include <unistd.h> | |
26 | #include <stdarg.h> | |
27 | #include <stdlib.h> | |
28 | #include <string.h> | |
29 | #include <stdbool.h> | |
30 | ||
31 | #include <seccomp.h> | |
32 | ||
33 | #include "arch.h" | |
34 | #include "db.h" | |
35 | #include "gen_pfc.h" | |
36 | #include "gen_bpf.h" | |
37 | #include "system.h" | |
38 | ||
39 | #define API __attribute__((visibility("default"))) | |
40 | ||
41 | const struct scmp_version library_version = { | |
42 | .major = SCMP_VER_MAJOR, | |
43 | .minor = SCMP_VER_MINOR, | |
44 | .micro = SCMP_VER_MICRO, | |
45 | }; | |
46 | ||
47 | /** | |
48 | * Validate a filter context | |
49 | * @param ctx the filter context | |
50 | * | |
51 | * Attempt to validate the provided filter context. Returns zero if the | |
52 | * context is valid, negative values on failure. | |
53 | * | |
54 | */ | |
55 | static int _ctx_valid(const scmp_filter_ctx *ctx) | |
56 | { | |
57 | return db_col_valid((struct db_filter_col *)ctx); | |
58 | } | |
59 | ||
60 | /** | |
61 | * Validate a syscall number | |
62 | * @param syscall the syscall number | |
63 | * | |
64 | * Attempt to perform basic syscall number validation. Returns zero of the | |
65 | * syscall appears valid, negative values on failure. | |
66 | * | |
67 | */ | |
68 | static int _syscall_valid(int syscall) | |
69 | { | |
70 | if (syscall <= -1 && syscall >= -99) | |
71 | return -EINVAL; | |
72 | return 0; | |
73 | } | |
74 | ||
75 | /* NOTE - function header comment in include/seccomp.h */ | |
76 | API const struct scmp_version *seccomp_version(void) | |
77 | { | |
78 | return &library_version; | |
79 | } | |
80 | ||
81 | /* NOTE - function header comment in include/seccomp.h */ | |
82 | API scmp_filter_ctx seccomp_init(uint32_t def_action) | |
83 | { | |
84 | if (db_action_valid(def_action) < 0) | |
85 | return NULL; | |
86 | ||
87 | return db_col_init(def_action); | |
88 | } | |
89 | ||
90 | /* NOTE - function header comment in include/seccomp.h */ | |
91 | API int seccomp_reset(scmp_filter_ctx ctx, uint32_t def_action) | |
92 | { | |
93 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
94 | ||
95 | if (ctx == NULL || db_action_valid(def_action) < 0) | |
96 | return -EINVAL; | |
97 | ||
98 | return db_col_reset(col, def_action); | |
99 | } | |
100 | ||
101 | /* NOTE - function header comment in include/seccomp.h */ | |
102 | API void seccomp_release(scmp_filter_ctx ctx) | |
103 | { | |
104 | db_col_release((struct db_filter_col *)ctx); | |
105 | } | |
106 | ||
107 | /* NOTE - function header comment in include/seccomp.h */ | |
108 | API int seccomp_merge(scmp_filter_ctx ctx_dst, | |
109 | scmp_filter_ctx ctx_src) | |
110 | { | |
111 | struct db_filter_col *col_dst = (struct db_filter_col *)ctx_dst; | |
112 | struct db_filter_col *col_src = (struct db_filter_col *)ctx_src; | |
113 | ||
114 | if (db_col_valid(col_dst) || db_col_valid(col_src)) | |
115 | return -EINVAL; | |
116 | ||
117 | /* NOTE: only the default action, NNP, and TSYNC settings must match */ | |
118 | if ((col_dst->attr.act_default != col_src->attr.act_default) || | |
119 | (col_dst->attr.nnp_enable != col_src->attr.nnp_enable) || | |
120 | (col_dst->attr.tsync_enable != col_src->attr.tsync_enable)) | |
121 | return -EINVAL; | |
122 | ||
123 | return db_col_merge(col_dst, col_src); | |
124 | } | |
125 | ||
126 | /* NOTE - function header comment in include/seccomp.h */ | |
127 | API uint32_t seccomp_arch_resolve_name(const char *arch_name) | |
128 | { | |
129 | const struct arch_def *arch; | |
130 | ||
131 | if (arch_name == NULL) | |
132 | return 0; | |
133 | ||
134 | arch = arch_def_lookup_name(arch_name); | |
135 | if (arch == NULL) | |
136 | return 0; | |
137 | ||
138 | return arch->token; | |
139 | } | |
140 | ||
141 | /* NOTE - function header comment in include/seccomp.h */ | |
142 | API uint32_t seccomp_arch_native(void) | |
143 | { | |
144 | return arch_def_native->token; | |
145 | } | |
146 | ||
147 | /* NOTE - function header comment in include/seccomp.h */ | |
148 | API int seccomp_arch_exist(const scmp_filter_ctx ctx, | |
149 | uint32_t arch_token) | |
150 | { | |
151 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
152 | ||
153 | if (arch_token == 0) | |
154 | arch_token = arch_def_native->token; | |
155 | ||
156 | if (arch_valid(arch_token)) | |
157 | return -EINVAL; | |
158 | ||
159 | return (db_col_arch_exist(col, arch_token) ? 0 : -EEXIST); | |
160 | } | |
161 | ||
162 | /* NOTE - function header comment in include/seccomp.h */ | |
163 | API int seccomp_arch_add(scmp_filter_ctx ctx, uint32_t arch_token) | |
164 | { | |
165 | const struct arch_def *arch; | |
166 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
167 | ||
168 | if (arch_token == 0) | |
169 | arch_token = arch_def_native->token; | |
170 | ||
171 | if (arch_valid(arch_token)) | |
172 | return -EINVAL; | |
173 | if (db_col_arch_exist(col, arch_token)) | |
174 | return -EEXIST; | |
175 | ||
176 | arch = arch_def_lookup(arch_token); | |
177 | if (arch == NULL) | |
178 | return -EFAULT; | |
179 | return db_col_db_new(col, arch); | |
180 | } | |
181 | ||
182 | /* NOTE - function header comment in include/seccomp.h */ | |
183 | API int seccomp_arch_remove(scmp_filter_ctx ctx, uint32_t arch_token) | |
184 | { | |
185 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
186 | ||
187 | if (arch_token == 0) | |
188 | arch_token = arch_def_native->token; | |
189 | ||
190 | if (arch_valid(arch_token)) | |
191 | return -EINVAL; | |
192 | if (db_col_arch_exist(col, arch_token) != -EEXIST) | |
193 | return -EEXIST; | |
194 | ||
195 | return db_col_db_remove(col, arch_token); | |
196 | } | |
197 | ||
198 | /* NOTE - function header comment in include/seccomp.h */ | |
199 | API int seccomp_load(const scmp_filter_ctx ctx) | |
200 | { | |
201 | struct db_filter_col *col; | |
202 | ||
203 | if (_ctx_valid(ctx)) | |
204 | return -EINVAL; | |
205 | col = (struct db_filter_col *)ctx; | |
206 | ||
207 | return sys_filter_load(col); | |
208 | } | |
209 | ||
210 | /* NOTE - function header comment in include/seccomp.h */ | |
211 | API int seccomp_attr_get(const scmp_filter_ctx ctx, | |
212 | enum scmp_filter_attr attr, uint32_t *value) | |
213 | { | |
214 | if (_ctx_valid(ctx)) | |
215 | return -EINVAL; | |
216 | ||
217 | return db_col_attr_get((const struct db_filter_col *)ctx, attr, value); | |
218 | } | |
219 | ||
220 | /* NOTE - function header comment in include/seccomp.h */ | |
221 | API int seccomp_attr_set(scmp_filter_ctx ctx, | |
222 | enum scmp_filter_attr attr, uint32_t value) | |
223 | { | |
224 | if (_ctx_valid(ctx)) | |
225 | return -EINVAL; | |
226 | ||
227 | return db_col_attr_set((struct db_filter_col *)ctx, attr, value); | |
228 | } | |
229 | ||
230 | /* NOTE - function header comment in include/seccomp.h */ | |
231 | API char *seccomp_syscall_resolve_num_arch(uint32_t arch_token, int num) | |
232 | { | |
233 | const struct arch_def *arch; | |
234 | const char *name; | |
235 | ||
236 | if (arch_token == 0) | |
237 | arch_token = arch_def_native->token; | |
238 | if (arch_valid(arch_token)) | |
239 | return NULL; | |
240 | arch = arch_def_lookup(arch_token); | |
241 | if (arch == NULL) | |
242 | return NULL; | |
243 | ||
244 | name = arch_syscall_resolve_num(arch, num); | |
245 | if (name == NULL) | |
246 | return NULL; | |
247 | ||
248 | return strdup(name); | |
249 | } | |
250 | ||
251 | /* NOTE - function header comment in include/seccomp.h */ | |
252 | API int seccomp_syscall_resolve_name_arch(uint32_t arch_token, const char *name) | |
253 | { | |
254 | const struct arch_def *arch; | |
255 | ||
256 | if (name == NULL) | |
257 | return __NR_SCMP_ERROR; | |
258 | ||
259 | if (arch_token == 0) | |
260 | arch_token = arch_def_native->token; | |
261 | if (arch_valid(arch_token)) | |
262 | return __NR_SCMP_ERROR; | |
263 | arch = arch_def_lookup(arch_token); | |
264 | if (arch == NULL) | |
265 | return __NR_SCMP_ERROR; | |
266 | ||
267 | return arch_syscall_resolve_name(arch, name); | |
268 | } | |
269 | ||
270 | /* NOTE - function header comment in include/seccomp.h */ | |
271 | API int seccomp_syscall_resolve_name_rewrite(uint32_t arch_token, | |
272 | const char *name) | |
273 | { | |
274 | int rc; | |
275 | int syscall; | |
276 | const struct arch_def *arch; | |
277 | ||
278 | if (name == NULL) | |
279 | return __NR_SCMP_ERROR; | |
280 | ||
281 | if (arch_token == 0) | |
282 | arch_token = arch_def_native->token; | |
283 | if (arch_valid(arch_token)) | |
284 | return __NR_SCMP_ERROR; | |
285 | arch = arch_def_lookup(arch_token); | |
286 | if (arch == NULL) | |
287 | return __NR_SCMP_ERROR; | |
288 | ||
289 | syscall = arch_syscall_resolve_name(arch, name); | |
290 | if (syscall == __NR_SCMP_ERROR) | |
291 | return __NR_SCMP_ERROR; | |
292 | rc = arch_syscall_rewrite(arch, &syscall); | |
293 | if (rc == -EDOM) | |
294 | /* if we can't rewrite the syscall, just pass it through */ | |
295 | return syscall; | |
296 | else if (rc < 0) | |
297 | return __NR_SCMP_ERROR; | |
298 | ||
299 | return syscall; | |
300 | } | |
301 | ||
302 | /* NOTE - function header comment in include/seccomp.h */ | |
303 | API int seccomp_syscall_resolve_name(const char *name) | |
304 | { | |
305 | return seccomp_syscall_resolve_name_arch(SCMP_ARCH_NATIVE, name); | |
306 | } | |
307 | ||
308 | /* NOTE - function header comment in include/seccomp.h */ | |
309 | API int seccomp_syscall_priority(scmp_filter_ctx ctx, | |
310 | int syscall, uint8_t priority) | |
311 | { | |
312 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
313 | ||
314 | if (db_col_valid(col) || _syscall_valid(syscall)) | |
315 | return -EINVAL; | |
316 | ||
317 | return db_col_syscall_priority(col, syscall, priority); | |
318 | } | |
319 | ||
320 | /* NOTE - function header comment in include/seccomp.h */ | |
321 | API int seccomp_rule_add_array(scmp_filter_ctx ctx, | |
322 | uint32_t action, int syscall, | |
323 | unsigned int arg_cnt, | |
324 | const struct scmp_arg_cmp *arg_array) | |
325 | { | |
326 | int rc; | |
327 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
328 | ||
329 | if (arg_cnt > ARG_COUNT_MAX) | |
330 | return -EINVAL; | |
331 | if (arg_cnt > 0 && arg_array == NULL) | |
332 | return -EINVAL; | |
333 | ||
334 | if (db_col_valid(col) || _syscall_valid(syscall)) | |
335 | return -EINVAL; | |
336 | ||
337 | rc = db_action_valid(action); | |
338 | if (rc < 0) | |
339 | return rc; | |
340 | if (action == col->attr.act_default) | |
341 | return -EPERM; | |
342 | ||
343 | return db_col_rule_add(col, 0, action, syscall, arg_cnt, arg_array); | |
344 | } | |
345 | ||
346 | /* NOTE - function header comment in include/seccomp.h */ | |
347 | API int seccomp_rule_add(scmp_filter_ctx ctx, | |
348 | uint32_t action, int syscall, | |
349 | unsigned int arg_cnt, ...) | |
350 | { | |
351 | int rc; | |
352 | int iter; | |
353 | struct scmp_arg_cmp arg_array[ARG_COUNT_MAX]; | |
354 | va_list arg_list; | |
355 | ||
356 | /* arg_cnt is unsigned, so no need to check the lower bound */ | |
357 | if (arg_cnt > ARG_COUNT_MAX) | |
358 | return -EINVAL; | |
359 | ||
360 | va_start(arg_list, arg_cnt); | |
361 | for (iter = 0; iter < arg_cnt; ++iter) | |
362 | arg_array[iter] = va_arg(arg_list, struct scmp_arg_cmp); | |
363 | rc = seccomp_rule_add_array(ctx, action, syscall, arg_cnt, arg_array); | |
364 | va_end(arg_list); | |
365 | ||
366 | return rc; | |
367 | } | |
368 | ||
369 | /* NOTE - function header comment in include/seccomp.h */ | |
370 | API int seccomp_rule_add_exact_array(scmp_filter_ctx ctx, | |
371 | uint32_t action, int syscall, | |
372 | unsigned int arg_cnt, | |
373 | const struct scmp_arg_cmp *arg_array) | |
374 | { | |
375 | int rc; | |
376 | struct db_filter_col *col = (struct db_filter_col *)ctx; | |
377 | ||
378 | if (arg_cnt > ARG_COUNT_MAX) | |
379 | return -EINVAL; | |
380 | if (arg_cnt > 0 && arg_array == NULL) | |
381 | return -EINVAL; | |
382 | ||
383 | if (db_col_valid(col) || _syscall_valid(syscall)) | |
384 | return -EINVAL; | |
385 | ||
386 | rc = db_action_valid(action); | |
387 | if (rc < 0) | |
388 | return rc; | |
389 | if (action == col->attr.act_default) | |
390 | return -EPERM; | |
391 | ||
392 | if (col->filter_cnt > 1) | |
393 | return -EOPNOTSUPP; | |
394 | ||
395 | return db_col_rule_add(col, 1, action, syscall, arg_cnt, arg_array); | |
396 | } | |
397 | ||
398 | /* NOTE - function header comment in include/seccomp.h */ | |
399 | API int seccomp_rule_add_exact(scmp_filter_ctx ctx, | |
400 | uint32_t action, int syscall, | |
401 | unsigned int arg_cnt, ...) | |
402 | { | |
403 | int rc; | |
404 | int iter; | |
405 | struct scmp_arg_cmp arg_array[ARG_COUNT_MAX]; | |
406 | va_list arg_list; | |
407 | ||
408 | /* arg_cnt is unsigned, so no need to check the lower bound */ | |
409 | if (arg_cnt > ARG_COUNT_MAX) | |
410 | return -EINVAL; | |
411 | ||
412 | va_start(arg_list, arg_cnt); | |
413 | for (iter = 0; iter < arg_cnt; ++iter) | |
414 | arg_array[iter] = va_arg(arg_list, struct scmp_arg_cmp); | |
415 | rc = seccomp_rule_add_exact_array(ctx, | |
416 | action, syscall, arg_cnt, arg_array); | |
417 | va_end(arg_list); | |
418 | ||
419 | return rc; | |
420 | } | |
421 | ||
422 | /* NOTE - function header comment in include/seccomp.h */ | |
423 | API int seccomp_export_pfc(const scmp_filter_ctx ctx, int fd) | |
424 | { | |
425 | if (_ctx_valid(ctx)) | |
426 | return -EINVAL; | |
427 | ||
428 | return gen_pfc_generate((struct db_filter_col *)ctx, fd); | |
429 | } | |
430 | ||
431 | /* NOTE - function header comment in include/seccomp.h */ | |
432 | API int seccomp_export_bpf(const scmp_filter_ctx ctx, int fd) | |
433 | { | |
434 | int rc; | |
435 | struct bpf_program *program; | |
436 | ||
437 | if (_ctx_valid(ctx)) | |
438 | return -EINVAL; | |
439 | ||
440 | program = gen_bpf_generate((struct db_filter_col *)ctx); | |
441 | if (program == NULL) | |
442 | return -ENOMEM; | |
443 | rc = write(fd, program->blks, BPF_PGM_SIZE(program)); | |
444 | gen_bpf_release(program); | |
445 | if (rc < 0) | |
446 | return -errno; | |
447 | ||
448 | return 0; | |
449 | } |