| 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 | LTTNG_HIDDEN |
| 92 | int lttng_directory_handle_copy(const struct lttng_directory_handle *handle, |
| 93 | struct lttng_directory_handle *new_copy) |
| 94 | { |
| 95 | int ret = 0; |
| 96 | |
| 97 | if (handle->dirfd == AT_FDCWD) { |
| 98 | new_copy->dirfd = handle->dirfd; |
| 99 | } else { |
| 100 | new_copy->dirfd = dup(handle->dirfd); |
| 101 | if (new_copy->dirfd == -1) { |
| 102 | PERROR("Failed to duplicate directory fd of directory handle"); |
| 103 | ret = -1; |
| 104 | } |
| 105 | } |
| 106 | return ret; |
| 107 | } |
| 108 | |
| 109 | static |
| 110 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, |
| 111 | const char *path, struct stat *st) |
| 112 | { |
| 113 | return fstatat(handle->dirfd, path, st, 0); |
| 114 | } |
| 115 | |
| 116 | static |
| 117 | int lttng_directory_handle_mkdir( |
| 118 | const struct lttng_directory_handle *handle, |
| 119 | const char *path, mode_t mode) |
| 120 | { |
| 121 | return mkdirat(handle->dirfd, path, mode); |
| 122 | } |
| 123 | |
| 124 | static |
| 125 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, |
| 126 | mode_t mode, uid_t uid, gid_t gid) |
| 127 | { |
| 128 | return run_as_mkdirat(handle->dirfd, path, mode, uid, gid); |
| 129 | } |
| 130 | |
| 131 | static |
| 132 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, |
| 133 | const char *path, mode_t mode, uid_t uid, gid_t gid) |
| 134 | { |
| 135 | return run_as_mkdirat_recursive(handle->dirfd, path, mode, uid, gid); |
| 136 | } |
| 137 | |
| 138 | #else /* COMPAT_DIRFD */ |
| 139 | |
| 140 | LTTNG_HIDDEN |
| 141 | int lttng_directory_handle_init(struct lttng_directory_handle *handle, |
| 142 | const char *path) |
| 143 | { |
| 144 | int ret; |
| 145 | size_t cwd_len, path_len, handle_path_len; |
| 146 | char cwd_buf[LTTNG_PATH_MAX]; |
| 147 | const char *cwd; |
| 148 | bool add_slash = false; |
| 149 | struct stat stat_buf; |
| 150 | |
| 151 | cwd = getcwd(cwd_buf, sizeof(cwd_buf)); |
| 152 | if (!cwd) { |
| 153 | PERROR("Failed to initialize directory handle, can't get current working directory"); |
| 154 | ret = -1; |
| 155 | goto end; |
| 156 | } |
| 157 | cwd_len = strlen(cwd); |
| 158 | if (cwd_len == 0) { |
| 159 | ERR("Failed to initialize directory handle to \"%s\": getcwd() returned an empty string", |
| 160 | path); |
| 161 | ret = -1; |
| 162 | goto end; |
| 163 | } |
| 164 | if (cwd[cwd_len - 1] != '/') { |
| 165 | add_slash = true; |
| 166 | } |
| 167 | |
| 168 | if (path) { |
| 169 | path_len = strlen(path); |
| 170 | if (path_len == 0) { |
| 171 | ERR("Failed to initialize directory handle: provided path is an empty string"); |
| 172 | ret = -1; |
| 173 | goto end; |
| 174 | } |
| 175 | |
| 176 | /* |
| 177 | * Ensure that 'path' is a directory. There is a race |
| 178 | * (TOCTOU) since the directory could be removed/replaced/renamed, |
| 179 | * but this is inevitable on platforms that don't provide dirfd support. |
| 180 | */ |
| 181 | ret = stat(path, &stat_buf); |
| 182 | if (ret == -1) { |
| 183 | PERROR("Failed to initialize directory handle to \"%s\", stat() failed", |
| 184 | path); |
| 185 | goto end; |
| 186 | } |
| 187 | if (!S_ISDIR(stat_buf.st_mode)) { |
| 188 | ERR("Failed to initialize directory handle to \"%s\": not a directory", |
| 189 | path); |
| 190 | ret = -1; |
| 191 | goto end; |
| 192 | } |
| 193 | if (*path == '/') { |
| 194 | handle->base_path = strdup(path); |
| 195 | if (!handle->base_path) { |
| 196 | ret = -1; |
| 197 | } |
| 198 | /* Not an error. */ |
| 199 | goto end; |
| 200 | } |
| 201 | } else { |
| 202 | path = ""; |
| 203 | path_len = 0; |
| 204 | add_slash = false; |
| 205 | } |
| 206 | |
| 207 | handle_path_len = cwd_len + path_len + !!add_slash + 2; |
| 208 | if (handle_path_len >= LTTNG_PATH_MAX) { |
| 209 | ERR("Failed to initialize directory handle as the resulting path's length (%zu bytes) exceeds the maximal allowed length (%d bytes)", |
| 210 | handle_path_len, LTTNG_PATH_MAX); |
| 211 | ret = -1; |
| 212 | goto end; |
| 213 | } |
| 214 | handle->base_path = zmalloc(handle_path_len); |
| 215 | if (!handle->base_path) { |
| 216 | PERROR("Failed to initialize directory handle"); |
| 217 | ret = -1; |
| 218 | goto end; |
| 219 | } |
| 220 | |
| 221 | ret = sprintf(handle->base_path, "%s%s%s/", cwd, |
| 222 | add_slash ? "/" : "", path); |
| 223 | if (ret == -1 || ret >= handle_path_len) { |
| 224 | ERR("Failed to initialize directory handle: path formatting failed"); |
| 225 | ret = -1; |
| 226 | goto end; |
| 227 | } |
| 228 | end: |
| 229 | return ret; |
| 230 | } |
| 231 | |
| 232 | LTTNG_HIDDEN |
| 233 | int lttng_directory_handle_init_from_dirfd( |
| 234 | struct lttng_directory_handle *handle, int dirfd) |
| 235 | { |
| 236 | assert(dirfd == AT_FDCWD); |
| 237 | return lttng_directory_handle_init(handle, NULL); |
| 238 | } |
| 239 | |
| 240 | LTTNG_HIDDEN |
| 241 | void lttng_directory_handle_fini(struct lttng_directory_handle *handle) |
| 242 | { |
| 243 | free(handle->base_path); |
| 244 | } |
| 245 | |
| 246 | LTTNG_HIDDEN |
| 247 | int lttng_directory_handle_copy(const struct lttng_directory_handle *handle, |
| 248 | struct lttng_directory_handle *new_copy) |
| 249 | { |
| 250 | new_copy->base_path = strdup(handle->base_path); |
| 251 | return new_copy->base_path ? 0 : -1; |
| 252 | } |
| 253 | |
| 254 | static |
| 255 | int get_full_path(const struct lttng_directory_handle *handle, |
| 256 | const char *subdirectory, char *fullpath, size_t size) |
| 257 | { |
| 258 | int ret; |
| 259 | |
| 260 | /* |
| 261 | * Don't include the base path if subdirectory is absolute. |
| 262 | * This is the same behaviour than mkdirat. |
| 263 | */ |
| 264 | ret = snprintf(fullpath, size, "%s%s", |
| 265 | *subdirectory != '/' ? handle->base_path : "", |
| 266 | subdirectory); |
| 267 | if (ret == -1 || ret >= size) { |
| 268 | ERR("Failed to format subdirectory from directory handle"); |
| 269 | ret = -1; |
| 270 | } |
| 271 | ret = 0; |
| 272 | return ret; |
| 273 | } |
| 274 | |
| 275 | static |
| 276 | int lttng_directory_handle_stat(const struct lttng_directory_handle *handle, |
| 277 | const char *subdirectory, struct stat *st) |
| 278 | { |
| 279 | int ret; |
| 280 | char fullpath[LTTNG_PATH_MAX]; |
| 281 | |
| 282 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); |
| 283 | if (ret) { |
| 284 | errno = ENOMEM; |
| 285 | goto end; |
| 286 | } |
| 287 | |
| 288 | ret = stat(fullpath, st); |
| 289 | end: |
| 290 | return ret; |
| 291 | } |
| 292 | |
| 293 | static |
| 294 | int lttng_directory_handle_mkdir(const struct lttng_directory_handle *handle, |
| 295 | const char *subdirectory, mode_t mode) |
| 296 | { |
| 297 | int ret; |
| 298 | char fullpath[LTTNG_PATH_MAX]; |
| 299 | |
| 300 | ret = get_full_path(handle, subdirectory, fullpath, sizeof(fullpath)); |
| 301 | if (ret) { |
| 302 | errno = ENOMEM; |
| 303 | goto end; |
| 304 | } |
| 305 | |
| 306 | ret = mkdir(fullpath, mode); |
| 307 | end: |
| 308 | return ret; |
| 309 | } |
| 310 | |
| 311 | static |
| 312 | int _run_as_mkdir(const struct lttng_directory_handle *handle, const char *path, |
| 313 | mode_t mode, uid_t uid, gid_t gid) |
| 314 | { |
| 315 | int ret; |
| 316 | char fullpath[LTTNG_PATH_MAX]; |
| 317 | |
| 318 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); |
| 319 | if (ret) { |
| 320 | errno = ENOMEM; |
| 321 | goto end; |
| 322 | } |
| 323 | |
| 324 | ret = run_as_mkdir(fullpath, mode, uid, gid); |
| 325 | end: |
| 326 | return ret; |
| 327 | } |
| 328 | |
| 329 | static |
| 330 | int _run_as_mkdir_recursive(const struct lttng_directory_handle *handle, |
| 331 | const char *path, mode_t mode, uid_t uid, gid_t gid) |
| 332 | { |
| 333 | int ret; |
| 334 | char fullpath[LTTNG_PATH_MAX]; |
| 335 | |
| 336 | ret = get_full_path(handle, path, fullpath, sizeof(fullpath)); |
| 337 | if (ret) { |
| 338 | errno = ENOMEM; |
| 339 | goto end; |
| 340 | } |
| 341 | |
| 342 | ret = run_as_mkdir_recursive(fullpath, mode, uid, gid); |
| 343 | end: |
| 344 | return ret; |
| 345 | } |
| 346 | |
| 347 | #endif /* COMPAT_DIRFD */ |
| 348 | |
| 349 | /* |
| 350 | * On some filesystems (e.g. nfs), mkdir will validate access rights before |
| 351 | * checking for the existence of the path element. This means that on a setup |
| 352 | * where "/home/" is a mounted NFS share, and running as an unpriviledged user, |
| 353 | * recursively creating a path of the form "/home/my_user/trace/" will fail with |
| 354 | * EACCES on mkdir("/home", ...). |
| 355 | * |
| 356 | * Checking the path for existence allows us to work around this behaviour. |
| 357 | */ |
| 358 | static |
| 359 | int create_directory_check_exists(const struct lttng_directory_handle *handle, |
| 360 | const char *path, mode_t mode) |
| 361 | { |
| 362 | int ret = 0; |
| 363 | struct stat st; |
| 364 | |
| 365 | ret = lttng_directory_handle_stat(handle, path, &st); |
| 366 | if (ret == 0) { |
| 367 | if (S_ISDIR(st.st_mode)) { |
| 368 | /* Directory exists, skip. */ |
| 369 | goto end; |
| 370 | } else { |
| 371 | /* Exists, but is not a directory. */ |
| 372 | errno = ENOTDIR; |
| 373 | ret = -1; |
| 374 | goto end; |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | /* |
| 379 | * Let mkdir handle other errors as the caller expects mkdir |
| 380 | * semantics. |
| 381 | */ |
| 382 | ret = lttng_directory_handle_mkdir(handle, path, mode); |
| 383 | end: |
| 384 | return ret; |
| 385 | } |
| 386 | |
| 387 | /* Common implementation. */ |
| 388 | static |
| 389 | int create_directory_recursive(const struct lttng_directory_handle *handle, |
| 390 | const char *path, mode_t mode) |
| 391 | { |
| 392 | char *p, tmp[LTTNG_PATH_MAX]; |
| 393 | size_t len; |
| 394 | int ret; |
| 395 | |
| 396 | assert(path); |
| 397 | |
| 398 | ret = lttng_strncpy(tmp, path, sizeof(tmp)); |
| 399 | if (ret) { |
| 400 | ERR("Failed to create directory: provided path's length (%zu bytes) exceeds the maximal allowed length (%zu bytes)", |
| 401 | strlen(path) + 1, sizeof(tmp)); |
| 402 | goto error; |
| 403 | } |
| 404 | |
| 405 | len = strlen(path); |
| 406 | if (tmp[len - 1] == '/') { |
| 407 | tmp[len - 1] = 0; |
| 408 | } |
| 409 | |
| 410 | for (p = tmp + 1; *p; p++) { |
| 411 | if (*p == '/') { |
| 412 | *p = 0; |
| 413 | if (tmp[strlen(tmp) - 1] == '.' && |
| 414 | tmp[strlen(tmp) - 2] == '.' && |
| 415 | tmp[strlen(tmp) - 3] == '/') { |
| 416 | ERR("Using '/../' is not permitted in the trace path (%s)", |
| 417 | tmp); |
| 418 | ret = -1; |
| 419 | goto error; |
| 420 | } |
| 421 | ret = create_directory_check_exists(handle, tmp, mode); |
| 422 | if (ret < 0) { |
| 423 | if (errno != EACCES) { |
| 424 | PERROR("Failed to create directory \"%s\"", |
| 425 | path); |
| 426 | ret = -errno; |
| 427 | goto error; |
| 428 | } |
| 429 | } |
| 430 | *p = '/'; |
| 431 | } |
| 432 | } |
| 433 | |
| 434 | ret = create_directory_check_exists(handle, tmp, mode); |
| 435 | if (ret < 0) { |
| 436 | PERROR("mkdirat recursive last element"); |
| 437 | ret = -errno; |
| 438 | } |
| 439 | error: |
| 440 | return ret; |
| 441 | } |
| 442 | |
| 443 | LTTNG_HIDDEN |
| 444 | int lttng_directory_handle_create_subdirectory_as_user( |
| 445 | const struct lttng_directory_handle *handle, |
| 446 | const char *subdirectory, |
| 447 | mode_t mode, const struct lttng_credentials *creds) |
| 448 | { |
| 449 | int ret; |
| 450 | |
| 451 | if (!creds) { |
| 452 | /* Run as current user. */ |
| 453 | ret = create_directory_check_exists(handle, |
| 454 | subdirectory, mode); |
| 455 | } else { |
| 456 | ret = _run_as_mkdir(handle, subdirectory, |
| 457 | mode, creds->uid, creds->gid); |
| 458 | } |
| 459 | |
| 460 | return ret; |
| 461 | } |
| 462 | |
| 463 | LTTNG_HIDDEN |
| 464 | int lttng_directory_handle_create_subdirectory_recursive_as_user( |
| 465 | const struct lttng_directory_handle *handle, |
| 466 | const char *subdirectory_path, |
| 467 | mode_t mode, const struct lttng_credentials *creds) |
| 468 | { |
| 469 | int ret; |
| 470 | |
| 471 | if (!creds) { |
| 472 | /* Run as current user. */ |
| 473 | ret = create_directory_recursive(handle, |
| 474 | subdirectory_path, mode); |
| 475 | } else { |
| 476 | ret = _run_as_mkdir_recursive(handle, subdirectory_path, |
| 477 | mode, creds->uid, creds->gid); |
| 478 | } |
| 479 | |
| 480 | return ret; |
| 481 | } |
| 482 | |
| 483 | LTTNG_HIDDEN |
| 484 | int lttng_directory_handle_create_subdirectory( |
| 485 | const struct lttng_directory_handle *handle, |
| 486 | const char *subdirectory, |
| 487 | mode_t mode) |
| 488 | { |
| 489 | return lttng_directory_handle_create_subdirectory_as_user( |
| 490 | handle, subdirectory, mode, NULL); |
| 491 | } |
| 492 | |
| 493 | LTTNG_HIDDEN |
| 494 | int lttng_directory_handle_create_subdirectory_recursive( |
| 495 | const struct lttng_directory_handle *handle, |
| 496 | const char *subdirectory_path, |
| 497 | mode_t mode) |
| 498 | { |
| 499 | return lttng_directory_handle_create_subdirectory_recursive_as_user( |
| 500 | handle, subdirectory_path, mode, NULL); |
| 501 | } |