Commit | Line | Data |
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18710679 JG |
1 | /* |
2 | * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License, version 2 only, | |
6 | * as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
11 | * more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License along | |
14 | * with this program; if not, write to the Free Software Foundation, Inc., | |
15 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
16 | */ | |
17 | ||
18 | #include <common/compat/directory-handle.h> | |
19 | #include <common/error.h> | |
20 | #include <common/macros.h> | |
21 | #include <common/runas.h> | |
22 | #include <common/credentials.h> | |
23 | #include <lttng/constant.h> | |
24 | ||
25 | #include <assert.h> | |
26 | #include <sys/types.h> | |
27 | #include <sys/stat.h> | |
28 | #include <fcntl.h> | |
29 | #include <unistd.h> | |
30 | ||
31 | static | |
32 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, | |
33 | const char *path, struct stat *st); | |
34 | static | |
35 | int lttng_directory_handle_mkdir( | |
36 | const struct lttng_directory_handle *handle, | |
37 | const char *path, mode_t mode); | |
38 | static | |
39 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, | |
40 | mode_t mode, uid_t uid, gid_t gid); | |
41 | static | |
42 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, | |
43 | const char *path, mode_t mode, uid_t uid, gid_t gid); | |
46307ffe JG |
44 | static |
45 | void lttng_directory_handle_invalidate(struct lttng_directory_handle *handle); | |
18710679 JG |
46 | |
47 | #ifdef COMPAT_DIRFD | |
48 | ||
49 | LTTNG_HIDDEN | |
50 | int lttng_directory_handle_init(struct lttng_directory_handle *handle, | |
51 | const char *path) | |
52 | { | |
53 | int ret; | |
54 | ||
55 | if (!path) { | |
56 | handle->dirfd = AT_FDCWD; | |
57 | ret = 0; | |
58 | goto end; | |
59 | } | |
60 | ret = open(path, O_RDONLY | O_DIRECTORY | O_CLOEXEC); | |
61 | if (ret == -1) { | |
62 | PERROR("Failed to initialize directory handle to \"%s\"", path); | |
63 | goto end; | |
64 | } | |
65 | handle->dirfd = ret; | |
66 | ret = 0; | |
67 | end: | |
68 | return ret; | |
69 | } | |
70 | ||
71 | LTTNG_HIDDEN | |
72 | int lttng_directory_handle_init_from_dirfd( | |
73 | struct lttng_directory_handle *handle, int dirfd) | |
74 | { | |
75 | handle->dirfd = dirfd; | |
76 | return 0; | |
77 | } | |
78 | ||
79 | LTTNG_HIDDEN | |
80 | void lttng_directory_handle_fini(struct lttng_directory_handle *handle) | |
81 | { | |
82 | int ret; | |
83 | ||
46307ffe JG |
84 | if (handle->dirfd == AT_FDCWD || handle->dirfd == -1) { |
85 | goto end; | |
18710679 JG |
86 | } |
87 | ret = close(handle->dirfd); | |
88 | if (ret == -1) { | |
89 | PERROR("Failed to close directory file descriptor of directory handle"); | |
90 | } | |
46307ffe JG |
91 | end: |
92 | lttng_directory_handle_invalidate(handle); | |
18710679 JG |
93 | } |
94 | ||
578e21bd JG |
95 | LTTNG_HIDDEN |
96 | int lttng_directory_handle_copy(const struct lttng_directory_handle *handle, | |
97 | struct lttng_directory_handle *new_copy) | |
98 | { | |
99 | int ret = 0; | |
100 | ||
101 | if (handle->dirfd == AT_FDCWD) { | |
102 | new_copy->dirfd = handle->dirfd; | |
103 | } else { | |
104 | new_copy->dirfd = dup(handle->dirfd); | |
105 | if (new_copy->dirfd == -1) { | |
106 | PERROR("Failed to duplicate directory fd of directory handle"); | |
107 | ret = -1; | |
108 | } | |
109 | } | |
110 | return ret; | |
111 | } | |
112 | ||
46307ffe JG |
113 | static |
114 | void lttng_directory_handle_invalidate(struct lttng_directory_handle *handle) | |
115 | { | |
116 | handle->dirfd = -1; | |
117 | } | |
118 | ||
18710679 JG |
119 | static |
120 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, | |
121 | const char *path, struct stat *st) | |
122 | { | |
123 | return fstatat(handle->dirfd, path, st, 0); | |
124 | } | |
125 | ||
126 | static | |
127 | int lttng_directory_handle_mkdir( | |
128 | const struct lttng_directory_handle *handle, | |
129 | const char *path, mode_t mode) | |
130 | { | |
131 | return mkdirat(handle->dirfd, path, mode); | |
132 | } | |
133 | ||
134 | static | |
135 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, | |
136 | mode_t mode, uid_t uid, gid_t gid) | |
137 | { | |
138 | return run_as_mkdirat(handle->dirfd, path, mode, uid, gid); | |
139 | } | |
140 | ||
141 | static | |
142 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, | |
143 | const char *path, mode_t mode, uid_t uid, gid_t gid) | |
144 | { | |
145 | return run_as_mkdirat_recursive(handle->dirfd, path, mode, uid, gid); | |
146 | } | |
147 | ||
148 | #else /* COMPAT_DIRFD */ | |
149 | ||
150 | LTTNG_HIDDEN | |
151 | int lttng_directory_handle_init(struct lttng_directory_handle *handle, | |
152 | const char *path) | |
153 | { | |
154 | int ret; | |
155 | size_t cwd_len, path_len, handle_path_len; | |
156 | char cwd_buf[LTTNG_PATH_MAX]; | |
157 | const char *cwd; | |
158 | bool add_slash = false; | |
159 | struct stat stat_buf; | |
160 | ||
161 | cwd = getcwd(cwd_buf, sizeof(cwd_buf)); | |
162 | if (!cwd) { | |
163 | PERROR("Failed to initialize directory handle, can't get current working directory"); | |
164 | ret = -1; | |
165 | goto end; | |
166 | } | |
167 | cwd_len = strlen(cwd); | |
168 | if (cwd_len == 0) { | |
169 | ERR("Failed to initialize directory handle to \"%s\": getcwd() returned an empty string", | |
170 | path); | |
171 | ret = -1; | |
172 | goto end; | |
173 | } | |
174 | if (cwd[cwd_len - 1] != '/') { | |
175 | add_slash = true; | |
176 | } | |
177 | ||
178 | if (path) { | |
179 | path_len = strlen(path); | |
180 | if (path_len == 0) { | |
181 | ERR("Failed to initialize directory handle: provided path is an empty string"); | |
182 | ret = -1; | |
183 | goto end; | |
184 | } | |
185 | ||
186 | /* | |
187 | * Ensure that 'path' is a directory. There is a race | |
188 | * (TOCTOU) since the directory could be removed/replaced/renamed, | |
189 | * but this is inevitable on platforms that don't provide dirfd support. | |
190 | */ | |
191 | ret = stat(path, &stat_buf); | |
192 | if (ret == -1) { | |
193 | PERROR("Failed to initialize directory handle to \"%s\", stat() failed", | |
194 | path); | |
195 | goto end; | |
196 | } | |
197 | if (!S_ISDIR(stat_buf.st_mode)) { | |
198 | ERR("Failed to initialize directory handle to \"%s\": not a directory", | |
199 | path); | |
200 | ret = -1; | |
201 | goto end; | |
202 | } | |
203 | if (*path == '/') { | |
204 | handle->base_path = strdup(path); | |
205 | if (!handle->base_path) { | |
206 | ret = -1; | |
207 | } | |
208 | /* Not an error. */ | |
209 | goto end; | |
210 | } | |
211 | } else { | |
212 | path = ""; | |
213 | path_len = 0; | |
214 | add_slash = false; | |
215 | } | |
216 | ||
217 | handle_path_len = cwd_len + path_len + !!add_slash + 2; | |
218 | if (handle_path_len >= LTTNG_PATH_MAX) { | |
219 | ERR("Failed to initialize directory handle as the resulting path's length (%zu bytes) exceeds the maximal allowed length (%d bytes)", | |
220 | handle_path_len, LTTNG_PATH_MAX); | |
221 | ret = -1; | |
222 | goto end; | |
223 | } | |
224 | handle->base_path = zmalloc(handle_path_len); | |
225 | if (!handle->base_path) { | |
226 | PERROR("Failed to initialize directory handle"); | |
227 | ret = -1; | |
228 | goto end; | |
229 | } | |
230 | ||
231 | ret = sprintf(handle->base_path, "%s%s%s/", cwd, | |
232 | add_slash ? "/" : "", path); | |
233 | if (ret == -1 || ret >= handle_path_len) { | |
234 | ERR("Failed to initialize directory handle: path formatting failed"); | |
235 | ret = -1; | |
236 | goto end; | |
237 | } | |
238 | end: | |
239 | return ret; | |
240 | } | |
241 | ||
242 | LTTNG_HIDDEN | |
243 | int lttng_directory_handle_init_from_dirfd( | |
244 | struct lttng_directory_handle *handle, int dirfd) | |
245 | { | |
246 | assert(dirfd == AT_FDCWD); | |
247 | return lttng_directory_handle_init(handle, NULL); | |
248 | } | |
249 | ||
250 | LTTNG_HIDDEN | |
251 | void lttng_directory_handle_fini(struct lttng_directory_handle *handle) | |
252 | { | |
253 | free(handle->base_path); | |
46307ffe | 254 | lttng_directory_handle_invalidate(handle); |
18710679 JG |
255 | } |
256 | ||
578e21bd JG |
257 | LTTNG_HIDDEN |
258 | int lttng_directory_handle_copy(const struct lttng_directory_handle *handle, | |
259 | struct lttng_directory_handle *new_copy) | |
260 | { | |
261 | new_copy->base_path = strdup(handle->base_path); | |
262 | return new_copy->base_path ? 0 : -1; | |
263 | } | |
264 | ||
46307ffe JG |
265 | static |
266 | void lttng_directory_handle_invalidate(struct lttng_directory_handle *handle) | |
267 | { | |
268 | handle->base_path = NULL; | |
269 | } | |
270 | ||
18710679 JG |
271 | static |
272 | int get_full_path(const struct lttng_directory_handle *handle, | |
273 | const char *subdirectory, char *fullpath, size_t size) | |
274 | { | |
275 | int ret; | |
276 | ||
277 | /* | |
278 | * Don't include the base path if subdirectory is absolute. | |
279 | * This is the same behaviour than mkdirat. | |
280 | */ | |
281 | ret = snprintf(fullpath, size, "%s%s", | |
282 | *subdirectory != '/' ? handle->base_path : "", | |
283 | subdirectory); | |
284 | if (ret == -1 || ret >= size) { | |
285 | ERR("Failed to format subdirectory from directory handle"); | |
286 | ret = -1; | |
287 | } | |
288 | ret = 0; | |
289 | return ret; | |
290 | } | |
291 | ||
292 | static | |
293 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, | |
294 | const char *subdirectory, struct stat *st) | |
295 | { | |
296 | int ret; | |
297 | char fullpath[LTTNG_PATH_MAX]; | |
298 | ||
299 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); | |
300 | if (ret) { | |
301 | errno = ENOMEM; | |
302 | goto end; | |
303 | } | |
304 | ||
305 | ret = stat(fullpath, st); | |
306 | end: | |
307 | return ret; | |
308 | } | |
309 | ||
310 | static | |
311 | int lttng_directory_handle_mkdir(const struct lttng_directory_handle *handle, | |
312 | const char *subdirectory, mode_t mode) | |
313 | { | |
314 | int ret; | |
315 | char fullpath[LTTNG_PATH_MAX]; | |
316 | ||
317 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); | |
318 | if (ret) { | |
319 | errno = ENOMEM; | |
320 | goto end; | |
321 | } | |
322 | ||
323 | ret = mkdir(fullpath, mode); | |
324 | end: | |
325 | return ret; | |
326 | } | |
327 | ||
328 | static | |
329 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, | |
330 | mode_t mode, uid_t uid, gid_t gid) | |
331 | { | |
332 | int ret; | |
333 | char fullpath[LTTNG_PATH_MAX]; | |
334 | ||
335 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); | |
336 | if (ret) { | |
337 | errno = ENOMEM; | |
338 | goto end; | |
339 | } | |
340 | ||
341 | ret = run_as_mkdir(fullpath, mode, uid, gid); | |
342 | end: | |
343 | return ret; | |
344 | } | |
345 | ||
346 | static | |
347 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, | |
348 | const char *path, mode_t mode, uid_t uid, gid_t gid) | |
349 | { | |
350 | int ret; | |
351 | char fullpath[LTTNG_PATH_MAX]; | |
352 | ||
353 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); | |
354 | if (ret) { | |
355 | errno = ENOMEM; | |
356 | goto end; | |
357 | } | |
358 | ||
359 | ret = run_as_mkdir_recursive(fullpath, mode, uid, gid); | |
360 | end: | |
361 | return ret; | |
362 | } | |
363 | ||
364 | #endif /* COMPAT_DIRFD */ | |
365 | ||
366 | /* | |
367 | * On some filesystems (e.g. nfs), mkdir will validate access rights before | |
368 | * checking for the existence of the path element. This means that on a setup | |
369 | * where "/home/" is a mounted NFS share, and running as an unpriviledged user, | |
370 | * recursively creating a path of the form "/home/my_user/trace/" will fail with | |
371 | * EACCES on mkdir("/home", ...). | |
372 | * | |
373 | * Checking the path for existence allows us to work around this behaviour. | |
374 | */ | |
375 | static | |
376 | int create_directory_check_exists(const struct lttng_directory_handle *handle, | |
377 | const char *path, mode_t mode) | |
378 | { | |
379 | int ret = 0; | |
380 | struct stat st; | |
381 | ||
382 | ret = lttng_directory_handle_stat(handle, path, &st); | |
383 | if (ret == 0) { | |
384 | if (S_ISDIR(st.st_mode)) { | |
385 | /* Directory exists, skip. */ | |
386 | goto end; | |
387 | } else { | |
388 | /* Exists, but is not a directory. */ | |
389 | errno = ENOTDIR; | |
390 | ret = -1; | |
391 | goto end; | |
392 | } | |
393 | } | |
394 | ||
395 | /* | |
396 | * Let mkdir handle other errors as the caller expects mkdir | |
397 | * semantics. | |
398 | */ | |
399 | ret = lttng_directory_handle_mkdir(handle, path, mode); | |
400 | end: | |
401 | return ret; | |
402 | } | |
403 | ||
404 | /* Common implementation. */ | |
46307ffe JG |
405 | LTTNG_HIDDEN |
406 | struct lttng_directory_handle | |
407 | lttng_directory_handle_move(struct lttng_directory_handle *original) | |
408 | { | |
409 | const struct lttng_directory_handle tmp = *original; | |
410 | ||
411 | lttng_directory_handle_invalidate(original); | |
412 | return tmp; | |
413 | } | |
414 | ||
18710679 JG |
415 | static |
416 | int create_directory_recursive(const struct lttng_directory_handle *handle, | |
417 | const char *path, mode_t mode) | |
418 | { | |
419 | char *p, tmp[LTTNG_PATH_MAX]; | |
420 | size_t len; | |
421 | int ret; | |
422 | ||
423 | assert(path); | |
424 | ||
425 | ret = lttng_strncpy(tmp, path, sizeof(tmp)); | |
426 | if (ret) { | |
427 | ERR("Failed to create directory: provided path's length (%zu bytes) exceeds the maximal allowed length (%zu bytes)", | |
428 | strlen(path) + 1, sizeof(tmp)); | |
429 | goto error; | |
430 | } | |
431 | ||
432 | len = strlen(path); | |
433 | if (tmp[len - 1] == '/') { | |
434 | tmp[len - 1] = 0; | |
435 | } | |
436 | ||
437 | for (p = tmp + 1; *p; p++) { | |
438 | if (*p == '/') { | |
439 | *p = 0; | |
440 | if (tmp[strlen(tmp) - 1] == '.' && | |
441 | tmp[strlen(tmp) - 2] == '.' && | |
442 | tmp[strlen(tmp) - 3] == '/') { | |
443 | ERR("Using '/../' is not permitted in the trace path (%s)", | |
444 | tmp); | |
445 | ret = -1; | |
446 | goto error; | |
447 | } | |
448 | ret = create_directory_check_exists(handle, tmp, mode); | |
449 | if (ret < 0) { | |
450 | if (errno != EACCES) { | |
451 | PERROR("Failed to create directory \"%s\"", | |
452 | path); | |
453 | ret = -errno; | |
454 | goto error; | |
455 | } | |
456 | } | |
457 | *p = '/'; | |
458 | } | |
459 | } | |
460 | ||
461 | ret = create_directory_check_exists(handle, tmp, mode); | |
462 | if (ret < 0) { | |
463 | PERROR("mkdirat recursive last element"); | |
464 | ret = -errno; | |
465 | } | |
466 | error: | |
467 | return ret; | |
468 | } | |
469 | ||
470 | LTTNG_HIDDEN | |
471 | int lttng_directory_handle_create_subdirectory_as_user( | |
472 | const struct lttng_directory_handle *handle, | |
473 | const char *subdirectory, | |
69e3a560 | 474 | mode_t mode, const struct lttng_credentials *creds) |
18710679 JG |
475 | { |
476 | int ret; | |
477 | ||
478 | if (!creds) { | |
479 | /* Run as current user. */ | |
480 | ret = create_directory_check_exists(handle, | |
481 | subdirectory, mode); | |
482 | } else { | |
483 | ret = _run_as_mkdir(handle, subdirectory, | |
484 | mode, creds->uid, creds->gid); | |
485 | } | |
486 | ||
487 | return ret; | |
488 | } | |
489 | ||
490 | LTTNG_HIDDEN | |
491 | int lttng_directory_handle_create_subdirectory_recursive_as_user( | |
492 | const struct lttng_directory_handle *handle, | |
493 | const char *subdirectory_path, | |
69e3a560 | 494 | mode_t mode, const struct lttng_credentials *creds) |
18710679 JG |
495 | { |
496 | int ret; | |
497 | ||
498 | if (!creds) { | |
499 | /* Run as current user. */ | |
500 | ret = create_directory_recursive(handle, | |
501 | subdirectory_path, mode); | |
502 | } else { | |
503 | ret = _run_as_mkdir_recursive(handle, subdirectory_path, | |
504 | mode, creds->uid, creds->gid); | |
505 | } | |
506 | ||
507 | return ret; | |
508 | } | |
509 | ||
510 | LTTNG_HIDDEN | |
511 | int lttng_directory_handle_create_subdirectory( | |
512 | const struct lttng_directory_handle *handle, | |
513 | const char *subdirectory, | |
514 | mode_t mode) | |
515 | { | |
516 | return lttng_directory_handle_create_subdirectory_as_user( | |
517 | handle, subdirectory, mode, NULL); | |
518 | } | |
519 | ||
520 | LTTNG_HIDDEN | |
521 | int lttng_directory_handle_create_subdirectory_recursive( | |
522 | const struct lttng_directory_handle *handle, | |
523 | const char *subdirectory_path, | |
524 | mode_t mode) | |
525 | { | |
526 | return lttng_directory_handle_create_subdirectory_recursive_as_user( | |
527 | handle, subdirectory_path, mode, NULL); | |
528 | } |