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a42089bd 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); | |
44 | ||
45 | #ifdef COMPAT_DIRFD | |
46 | ||
47 | LTTNG_HIDDEN | |
48 | int lttng_directory_handle_init(struct lttng_directory_handle *handle, | |
49 | const char *path) | |
50 | { | |
51 | int ret; | |
52 | ||
53 | if (!path) { | |
54 | handle->dirfd = AT_FDCWD; | |
55 | ret = 0; | |
56 | goto end; | |
57 | } | |
58 | ret = open(path, O_RDONLY | O_DIRECTORY | O_CLOEXEC); | |
59 | if (ret == -1) { | |
60 | PERROR("Failed to initialize directory handle to \"%s\"", path); | |
61 | goto end; | |
62 | } | |
63 | handle->dirfd = ret; | |
64 | ret = 0; | |
65 | end: | |
66 | return ret; | |
67 | } | |
68 | ||
69 | LTTNG_HIDDEN | |
70 | int lttng_directory_handle_init_from_dirfd( | |
71 | struct lttng_directory_handle *handle, int dirfd) | |
72 | { | |
73 | handle->dirfd = dirfd; | |
74 | return 0; | |
75 | } | |
76 | ||
77 | LTTNG_HIDDEN | |
78 | void lttng_directory_handle_fini(struct lttng_directory_handle *handle) | |
79 | { | |
80 | int ret; | |
81 | ||
82 | if (handle->dirfd == AT_FDCWD) { | |
83 | return; | |
84 | } | |
85 | ret = close(handle->dirfd); | |
86 | if (ret == -1) { | |
87 | PERROR("Failed to close directory file descriptor of directory handle"); | |
88 | } | |
89 | } | |
90 | ||
91 | static | |
92 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, | |
93 | const char *path, struct stat *st) | |
94 | { | |
95 | return fstatat(handle->dirfd, path, st, 0); | |
96 | } | |
97 | ||
98 | static | |
99 | int lttng_directory_handle_mkdir( | |
100 | const struct lttng_directory_handle *handle, | |
101 | const char *path, mode_t mode) | |
102 | { | |
103 | return mkdirat(handle->dirfd, path, mode); | |
104 | } | |
105 | ||
106 | static | |
107 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, | |
108 | mode_t mode, uid_t uid, gid_t gid) | |
109 | { | |
110 | return run_as_mkdirat(handle->dirfd, path, mode, uid, gid); | |
111 | } | |
112 | ||
113 | static | |
114 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, | |
115 | const char *path, mode_t mode, uid_t uid, gid_t gid) | |
116 | { | |
117 | return run_as_mkdirat_recursive(handle->dirfd, path, mode, uid, gid); | |
118 | } | |
119 | ||
120 | #else /* COMPAT_DIRFD */ | |
121 | ||
122 | LTTNG_HIDDEN | |
123 | int lttng_directory_handle_init(struct lttng_directory_handle *handle, | |
124 | const char *path) | |
125 | { | |
126 | int ret; | |
127 | size_t cwd_len, path_len, handle_path_len; | |
128 | char cwd_buf[LTTNG_PATH_MAX]; | |
129 | const char *cwd; | |
130 | bool add_slash = false; | |
131 | struct stat stat_buf; | |
132 | ||
133 | cwd = getcwd(cwd_buf, sizeof(cwd_buf)); | |
134 | if (!cwd) { | |
135 | PERROR("Failed to initialize directory handle, can't get current working directory"); | |
136 | ret = -1; | |
137 | goto end; | |
138 | } | |
139 | cwd_len = strlen(cwd); | |
140 | if (cwd_len == 0) { | |
141 | ERR("Failed to initialize directory handle to \"%s\": getcwd() returned an empty string", | |
142 | path); | |
143 | ret = -1; | |
144 | goto end; | |
145 | } | |
146 | if (cwd[cwd_len - 1] != '/') { | |
147 | add_slash = true; | |
148 | } | |
149 | ||
150 | if (path) { | |
151 | path_len = strlen(path); | |
152 | if (path_len == 0) { | |
153 | ERR("Failed to initialize directory handle: provided path is an empty string"); | |
154 | ret = -1; | |
155 | goto end; | |
156 | } | |
157 | ||
158 | /* | |
159 | * Ensure that 'path' is a directory. There is a race | |
160 | * (TOCTOU) since the directory could be removed/replaced/renamed, | |
161 | * but this is inevitable on platforms that don't provide dirfd support. | |
162 | */ | |
163 | ret = stat(path, &stat_buf); | |
164 | if (ret == -1) { | |
165 | PERROR("Failed to initialize directory handle to \"%s\", stat() failed", | |
166 | path); | |
167 | goto end; | |
168 | } | |
169 | if (!S_ISDIR(stat_buf.st_mode)) { | |
170 | ERR("Failed to initialize directory handle to \"%s\": not a directory", | |
171 | path); | |
172 | ret = -1; | |
173 | goto end; | |
174 | } | |
175 | if (*path == '/') { | |
176 | handle->base_path = strdup(path); | |
177 | if (!handle->base_path) { | |
178 | ret = -1; | |
179 | } | |
180 | /* Not an error. */ | |
181 | goto end; | |
182 | } | |
183 | } else { | |
184 | path = ""; | |
185 | path_len = 0; | |
186 | add_slash = false; | |
187 | } | |
188 | ||
189 | handle_path_len = cwd_len + path_len + !!add_slash + 2; | |
190 | if (handle_path_len >= LTTNG_PATH_MAX) { | |
191 | ERR("Failed to initialize directory handle as the resulting path's length (%zu bytes) exceeds the maximal allowed length (%d bytes)", | |
192 | handle_path_len, LTTNG_PATH_MAX); | |
193 | ret = -1; | |
194 | goto end; | |
195 | } | |
196 | handle->base_path = zmalloc(handle_path_len); | |
197 | if (!handle->base_path) { | |
198 | PERROR("Failed to initialize directory handle"); | |
199 | ret = -1; | |
200 | goto end; | |
201 | } | |
202 | ||
203 | ret = sprintf(handle->base_path, "%s%s%s/", cwd, | |
204 | add_slash ? "/" : "", path); | |
205 | if (ret == -1 || ret >= handle_path_len) { | |
206 | ERR("Failed to initialize directory handle: path formatting failed"); | |
207 | ret = -1; | |
208 | goto end; | |
209 | } | |
210 | end: | |
211 | return ret; | |
212 | } | |
213 | ||
214 | LTTNG_HIDDEN | |
215 | int lttng_directory_handle_init_from_dirfd( | |
216 | struct lttng_directory_handle *handle, int dirfd) | |
217 | { | |
218 | assert(dirfd == AT_FDCWD); | |
219 | return lttng_directory_handle_init(handle, NULL); | |
220 | } | |
221 | ||
222 | LTTNG_HIDDEN | |
223 | void lttng_directory_handle_fini(struct lttng_directory_handle *handle) | |
224 | { | |
225 | free(handle->base_path); | |
226 | } | |
227 | ||
228 | static | |
229 | int get_full_path(const struct lttng_directory_handle *handle, | |
230 | const char *subdirectory, char *fullpath, size_t size) | |
231 | { | |
232 | int ret; | |
233 | ||
234 | /* | |
235 | * Don't include the base path if subdirectory is absolute. | |
236 | * This is the same behaviour than mkdirat. | |
237 | */ | |
238 | ret = snprintf(fullpath, size, "%s%s", | |
239 | *subdirectory != '/' ? handle->base_path : "", | |
240 | subdirectory); | |
241 | if (ret == -1 || ret >= size) { | |
242 | ERR("Failed to format subdirectory from directory handle"); | |
243 | ret = -1; | |
244 | } | |
245 | ret = 0; | |
246 | return ret; | |
247 | } | |
248 | ||
249 | static | |
250 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, | |
251 | const char *subdirectory, struct stat *st) | |
252 | { | |
253 | int ret; | |
254 | char fullpath[LTTNG_PATH_MAX]; | |
255 | ||
256 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); | |
257 | if (ret) { | |
258 | errno = ENOMEM; | |
259 | goto end; | |
260 | } | |
261 | ||
262 | ret = stat(fullpath, st); | |
263 | end: | |
264 | return ret; | |
265 | } | |
266 | ||
267 | static | |
268 | int lttng_directory_handle_mkdir(const struct lttng_directory_handle *handle, | |
269 | const char *subdirectory, mode_t mode) | |
270 | { | |
271 | int ret; | |
272 | char fullpath[LTTNG_PATH_MAX]; | |
273 | ||
274 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); | |
275 | if (ret) { | |
276 | errno = ENOMEM; | |
277 | goto end; | |
278 | } | |
279 | ||
280 | ret = mkdir(fullpath, mode); | |
281 | end: | |
282 | return ret; | |
283 | } | |
284 | ||
285 | static | |
286 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, | |
287 | mode_t mode, uid_t uid, gid_t gid) | |
288 | { | |
289 | int ret; | |
290 | char fullpath[LTTNG_PATH_MAX]; | |
291 | ||
292 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); | |
293 | if (ret) { | |
294 | errno = ENOMEM; | |
295 | goto end; | |
296 | } | |
297 | ||
298 | ret = run_as_mkdir(fullpath, mode, uid, gid); | |
299 | end: | |
300 | return ret; | |
301 | } | |
302 | ||
303 | static | |
304 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, | |
305 | const char *path, mode_t mode, uid_t uid, gid_t gid) | |
306 | { | |
307 | int ret; | |
308 | char fullpath[LTTNG_PATH_MAX]; | |
309 | ||
310 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); | |
311 | if (ret) { | |
312 | errno = ENOMEM; | |
313 | goto end; | |
314 | } | |
315 | ||
316 | ret = run_as_mkdir_recursive(fullpath, mode, uid, gid); | |
317 | end: | |
318 | return ret; | |
319 | } | |
320 | ||
321 | #endif /* COMPAT_DIRFD */ | |
322 | ||
323 | /* | |
324 | * On some filesystems (e.g. nfs), mkdir will validate access rights before | |
325 | * checking for the existence of the path element. This means that on a setup | |
326 | * where "/home/" is a mounted NFS share, and running as an unpriviledged user, | |
327 | * recursively creating a path of the form "/home/my_user/trace/" will fail with | |
328 | * EACCES on mkdir("/home", ...). | |
329 | * | |
330 | * Checking the path for existence allows us to work around this behaviour. | |
331 | */ | |
332 | static | |
333 | int create_directory_check_exists(const struct lttng_directory_handle *handle, | |
334 | const char *path, mode_t mode) | |
335 | { | |
336 | int ret = 0; | |
337 | struct stat st; | |
338 | ||
339 | ret = lttng_directory_handle_stat(handle, path, &st); | |
340 | if (ret == 0) { | |
341 | if (S_ISDIR(st.st_mode)) { | |
342 | /* Directory exists, skip. */ | |
343 | goto end; | |
344 | } else { | |
345 | /* Exists, but is not a directory. */ | |
346 | errno = ENOTDIR; | |
347 | ret = -1; | |
348 | goto end; | |
349 | } | |
350 | } | |
351 | ||
352 | /* | |
353 | * Let mkdir handle other errors as the caller expects mkdir | |
354 | * semantics. | |
355 | */ | |
356 | ret = lttng_directory_handle_mkdir(handle, path, mode); | |
357 | end: | |
358 | return ret; | |
359 | } | |
360 | ||
361 | /* Common implementation. */ | |
362 | static | |
363 | int create_directory_recursive(const struct lttng_directory_handle *handle, | |
364 | const char *path, mode_t mode) | |
365 | { | |
366 | char *p, tmp[LTTNG_PATH_MAX]; | |
367 | size_t len; | |
368 | int ret; | |
369 | ||
370 | assert(path); | |
371 | ||
372 | ret = lttng_strncpy(tmp, path, sizeof(tmp)); | |
373 | if (ret) { | |
374 | ERR("Failed to create directory: provided path's length (%zu bytes) exceeds the maximal allowed length (%zu bytes)", | |
375 | strlen(path) + 1, sizeof(tmp)); | |
376 | goto error; | |
377 | } | |
378 | ||
379 | len = strlen(path); | |
380 | if (tmp[len - 1] == '/') { | |
381 | tmp[len - 1] = 0; | |
382 | } | |
383 | ||
384 | for (p = tmp + 1; *p; p++) { | |
385 | if (*p == '/') { | |
386 | *p = 0; | |
387 | if (tmp[strlen(tmp) - 1] == '.' && | |
388 | tmp[strlen(tmp) - 2] == '.' && | |
389 | tmp[strlen(tmp) - 3] == '/') { | |
390 | ERR("Using '/../' is not permitted in the trace path (%s)", | |
391 | tmp); | |
392 | ret = -1; | |
393 | goto error; | |
394 | } | |
395 | ret = create_directory_check_exists(handle, tmp, mode); | |
396 | if (ret < 0) { | |
397 | if (errno != EACCES) { | |
398 | PERROR("Failed to create directory \"%s\"", | |
399 | path); | |
400 | ret = -errno; | |
401 | goto error; | |
402 | } | |
403 | } | |
404 | *p = '/'; | |
405 | } | |
406 | } | |
407 | ||
408 | ret = create_directory_check_exists(handle, tmp, mode); | |
409 | if (ret < 0) { | |
410 | PERROR("mkdirat recursive last element"); | |
411 | ret = -errno; | |
412 | } | |
413 | error: | |
414 | return ret; | |
415 | } | |
416 | ||
417 | LTTNG_HIDDEN | |
418 | int lttng_directory_handle_create_subdirectory_as_user( | |
419 | const struct lttng_directory_handle *handle, | |
420 | const char *subdirectory, | |
6992f9f1 | 421 | mode_t mode, const struct lttng_credentials *creds) |
a42089bd JG |
422 | { |
423 | int ret; | |
424 | ||
425 | if (!creds) { | |
426 | /* Run as current user. */ | |
427 | ret = create_directory_check_exists(handle, | |
428 | subdirectory, mode); | |
429 | } else { | |
430 | ret = _run_as_mkdir(handle, subdirectory, | |
431 | mode, creds->uid, creds->gid); | |
432 | } | |
433 | ||
434 | return ret; | |
435 | } | |
436 | ||
437 | LTTNG_HIDDEN | |
438 | int lttng_directory_handle_create_subdirectory_recursive_as_user( | |
439 | const struct lttng_directory_handle *handle, | |
440 | const char *subdirectory_path, | |
6992f9f1 | 441 | mode_t mode, const struct lttng_credentials *creds) |
a42089bd JG |
442 | { |
443 | int ret; | |
444 | ||
445 | if (!creds) { | |
446 | /* Run as current user. */ | |
447 | ret = create_directory_recursive(handle, | |
448 | subdirectory_path, mode); | |
449 | } else { | |
450 | ret = _run_as_mkdir_recursive(handle, subdirectory_path, | |
451 | mode, creds->uid, creds->gid); | |
452 | } | |
453 | ||
454 | return ret; | |
455 | } | |
456 | ||
457 | LTTNG_HIDDEN | |
458 | int lttng_directory_handle_create_subdirectory( | |
459 | const struct lttng_directory_handle *handle, | |
460 | const char *subdirectory, | |
461 | mode_t mode) | |
462 | { | |
463 | return lttng_directory_handle_create_subdirectory_as_user( | |
464 | handle, subdirectory, mode, NULL); | |
465 | } | |
466 | ||
467 | LTTNG_HIDDEN | |
468 | int lttng_directory_handle_create_subdirectory_recursive( | |
469 | const struct lttng_directory_handle *handle, | |
470 | const char *subdirectory_path, | |
471 | mode_t mode) | |
472 | { | |
473 | return lttng_directory_handle_create_subdirectory_recursive_as_user( | |
474 | handle, subdirectory_path, mode, NULL); | |
475 | } |