1 /* 2 * linux/fs/ext4/acl.c 3 * 4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de> 5 */ 6 7 #include <linux/init.h> 8 #include <linux/sched.h> 9 #include <linux/slab.h> 10 #include <linux/capability.h> 11 #include <linux/fs.h> 12 #include "ext4_jbd2.h" 13 #include "ext4.h" 14 #include "xattr.h" 15 #include "acl.h" 16 17 /* 18 * Convert from filesystem to in-memory representation. 19 */ 20 static struct posix_acl * 21 ext4_acl_from_disk(const void *value, size_t size) 22 { 23 const char *end = (char *)value + size; 24 int n, count; 25 struct posix_acl *acl; 26 27 if (!value) 28 return NULL; 29 if (size < sizeof(ext4_acl_header)) 30 return ERR_PTR(-EINVAL); 31 if (((ext4_acl_header *)value)->a_version != 32 cpu_to_le32(EXT4_ACL_VERSION)) 33 return ERR_PTR(-EINVAL); 34 value = (char *)value + sizeof(ext4_acl_header); 35 count = ext4_acl_count(size); 36 if (count < 0) 37 return ERR_PTR(-EINVAL); 38 if (count == 0) 39 return NULL; 40 acl = posix_acl_alloc(count, GFP_NOFS); 41 if (!acl) 42 return ERR_PTR(-ENOMEM); 43 for (n = 0; n < count; n++) { 44 ext4_acl_entry *entry = 45 (ext4_acl_entry *)value; 46 if ((char *)value + sizeof(ext4_acl_entry_short) > end) 47 goto fail; 48 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag); 49 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm); 50 51 switch (acl->a_entries[n].e_tag) { 52 case ACL_USER_OBJ: 53 case ACL_GROUP_OBJ: 54 case ACL_MASK: 55 case ACL_OTHER: 56 value = (char *)value + 57 sizeof(ext4_acl_entry_short); 58 acl->a_entries[n].e_id = ACL_UNDEFINED_ID; 59 break; 60 61 case ACL_USER: 62 case ACL_GROUP: 63 value = (char *)value + sizeof(ext4_acl_entry); 64 if ((char *)value > end) 65 goto fail; 66 acl->a_entries[n].e_id = 67 le32_to_cpu(entry->e_id); 68 break; 69 70 default: 71 goto fail; 72 } 73 } 74 if (value != end) 75 goto fail; 76 return acl; 77 78 fail: 79 posix_acl_release(acl); 80 return ERR_PTR(-EINVAL); 81 } 82 83 /* 84 * Convert from in-memory to filesystem representation. 85 */ 86 static void * 87 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size) 88 { 89 ext4_acl_header *ext_acl; 90 char *e; 91 size_t n; 92 93 *size = ext4_acl_size(acl->a_count); 94 ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count * 95 sizeof(ext4_acl_entry), GFP_NOFS); 96 if (!ext_acl) 97 return ERR_PTR(-ENOMEM); 98 ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION); 99 e = (char *)ext_acl + sizeof(ext4_acl_header); 100 for (n = 0; n < acl->a_count; n++) { 101 ext4_acl_entry *entry = (ext4_acl_entry *)e; 102 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag); 103 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm); 104 switch (acl->a_entries[n].e_tag) { 105 case ACL_USER: 106 case ACL_GROUP: 107 entry->e_id = cpu_to_le32(acl->a_entries[n].e_id); 108 e += sizeof(ext4_acl_entry); 109 break; 110 111 case ACL_USER_OBJ: 112 case ACL_GROUP_OBJ: 113 case ACL_MASK: 114 case ACL_OTHER: 115 e += sizeof(ext4_acl_entry_short); 116 break; 117 118 default: 119 goto fail; 120 } 121 } 122 return (char *)ext_acl; 123 124 fail: 125 kfree(ext_acl); 126 return ERR_PTR(-EINVAL); 127 } 128 129 /* 130 * Inode operation get_posix_acl(). 131 * 132 * inode->i_mutex: don't care 133 */ 134 static struct posix_acl * 135 ext4_get_acl(struct inode *inode, int type) 136 { 137 int name_index; 138 char *value = NULL; 139 struct posix_acl *acl; 140 int retval; 141 142 if (!test_opt(inode->i_sb, POSIX_ACL)) 143 return NULL; 144 145 acl = get_cached_acl(inode, type); 146 if (acl != ACL_NOT_CACHED) 147 return acl; 148 149 switch (type) { 150 case ACL_TYPE_ACCESS: 151 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 152 break; 153 case ACL_TYPE_DEFAULT: 154 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 155 break; 156 default: 157 BUG(); 158 } 159 retval = ext4_xattr_get(inode, name_index, "", NULL, 0); 160 if (retval > 0) { 161 value = kmalloc(retval, GFP_NOFS); 162 if (!value) 163 return ERR_PTR(-ENOMEM); 164 retval = ext4_xattr_get(inode, name_index, "", value, retval); 165 } 166 if (retval > 0) 167 acl = ext4_acl_from_disk(value, retval); 168 else if (retval == -ENODATA || retval == -ENOSYS) 169 acl = NULL; 170 else 171 acl = ERR_PTR(retval); 172 kfree(value); 173 174 if (!IS_ERR(acl)) 175 set_cached_acl(inode, type, acl); 176 177 return acl; 178 } 179 180 /* 181 * Set the access or default ACL of an inode. 182 * 183 * inode->i_mutex: down unless called from ext4_new_inode 184 */ 185 static int 186 ext4_set_acl(handle_t *handle, struct inode *inode, int type, 187 struct posix_acl *acl) 188 { 189 int name_index; 190 void *value = NULL; 191 size_t size = 0; 192 int error; 193 194 if (S_ISLNK(inode->i_mode)) 195 return -EOPNOTSUPP; 196 197 switch (type) { 198 case ACL_TYPE_ACCESS: 199 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 200 if (acl) { 201 mode_t mode = inode->i_mode; 202 error = posix_acl_equiv_mode(acl, &mode); 203 if (error < 0) 204 return error; 205 else { 206 inode->i_mode = mode; 207 ext4_mark_inode_dirty(handle, inode); 208 if (error == 0) 209 acl = NULL; 210 } 211 } 212 break; 213 214 case ACL_TYPE_DEFAULT: 215 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 216 if (!S_ISDIR(inode->i_mode)) 217 return acl ? -EACCES : 0; 218 break; 219 220 default: 221 return -EINVAL; 222 } 223 if (acl) { 224 value = ext4_acl_to_disk(acl, &size); 225 if (IS_ERR(value)) 226 return (int)PTR_ERR(value); 227 } 228 229 error = ext4_xattr_set_handle(handle, inode, name_index, "", 230 value, size, 0); 231 232 kfree(value); 233 if (!error) 234 set_cached_acl(inode, type, acl); 235 236 return error; 237 } 238 239 static int 240 ext4_check_acl(struct inode *inode, int mask) 241 { 242 struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 243 244 if (IS_ERR(acl)) 245 return PTR_ERR(acl); 246 if (acl) { 247 int error = posix_acl_permission(inode, acl, mask); 248 posix_acl_release(acl); 249 return error; 250 } 251 252 return -EAGAIN; 253 } 254 255 int 256 ext4_permission(struct inode *inode, int mask) 257 { 258 return generic_permission(inode, mask, ext4_check_acl); 259 } 260 261 /* 262 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 263 * 264 * dir->i_mutex: down 265 * inode->i_mutex: up (access to inode is still exclusive) 266 */ 267 int 268 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 269 { 270 struct posix_acl *acl = NULL; 271 int error = 0; 272 273 if (!S_ISLNK(inode->i_mode)) { 274 if (test_opt(dir->i_sb, POSIX_ACL)) { 275 acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); 276 if (IS_ERR(acl)) 277 return PTR_ERR(acl); 278 } 279 if (!acl) 280 inode->i_mode &= ~current_umask(); 281 } 282 if (test_opt(inode->i_sb, POSIX_ACL) && acl) { 283 struct posix_acl *clone; 284 mode_t mode; 285 286 if (S_ISDIR(inode->i_mode)) { 287 error = ext4_set_acl(handle, inode, 288 ACL_TYPE_DEFAULT, acl); 289 if (error) 290 goto cleanup; 291 } 292 clone = posix_acl_clone(acl, GFP_NOFS); 293 error = -ENOMEM; 294 if (!clone) 295 goto cleanup; 296 297 mode = inode->i_mode; 298 error = posix_acl_create_masq(clone, &mode); 299 if (error >= 0) { 300 inode->i_mode = mode; 301 if (error > 0) { 302 /* This is an extended ACL */ 303 error = ext4_set_acl(handle, inode, 304 ACL_TYPE_ACCESS, clone); 305 } 306 } 307 posix_acl_release(clone); 308 } 309 cleanup: 310 posix_acl_release(acl); 311 return error; 312 } 313 314 /* 315 * Does chmod for an inode that may have an Access Control List. The 316 * inode->i_mode field must be updated to the desired value by the caller 317 * before calling this function. 318 * Returns 0 on success, or a negative error number. 319 * 320 * We change the ACL rather than storing some ACL entries in the file 321 * mode permission bits (which would be more efficient), because that 322 * would break once additional permissions (like ACL_APPEND, ACL_DELETE 323 * for directories) are added. There are no more bits available in the 324 * file mode. 325 * 326 * inode->i_mutex: down 327 */ 328 int 329 ext4_acl_chmod(struct inode *inode) 330 { 331 struct posix_acl *acl, *clone; 332 int error; 333 334 if (S_ISLNK(inode->i_mode)) 335 return -EOPNOTSUPP; 336 if (!test_opt(inode->i_sb, POSIX_ACL)) 337 return 0; 338 acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 339 if (IS_ERR(acl) || !acl) 340 return PTR_ERR(acl); 341 clone = posix_acl_clone(acl, GFP_KERNEL); 342 posix_acl_release(acl); 343 if (!clone) 344 return -ENOMEM; 345 error = posix_acl_chmod_masq(clone, inode->i_mode); 346 if (!error) { 347 handle_t *handle; 348 int retries = 0; 349 350 retry: 351 handle = ext4_journal_start(inode, 352 EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 353 if (IS_ERR(handle)) { 354 error = PTR_ERR(handle); 355 ext4_std_error(inode->i_sb, error); 356 goto out; 357 } 358 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone); 359 ext4_journal_stop(handle); 360 if (error == -ENOSPC && 361 ext4_should_retry_alloc(inode->i_sb, &retries)) 362 goto retry; 363 } 364 out: 365 posix_acl_release(clone); 366 return error; 367 } 368 369 /* 370 * Extended attribute handlers 371 */ 372 static size_t 373 ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len, 374 const char *name, size_t name_len) 375 { 376 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); 377 378 if (!test_opt(inode->i_sb, POSIX_ACL)) 379 return 0; 380 if (list && size <= list_len) 381 memcpy(list, POSIX_ACL_XATTR_ACCESS, size); 382 return size; 383 } 384 385 static size_t 386 ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len, 387 const char *name, size_t name_len) 388 { 389 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); 390 391 if (!test_opt(inode->i_sb, POSIX_ACL)) 392 return 0; 393 if (list && size <= list_len) 394 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); 395 return size; 396 } 397 398 static int 399 ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size) 400 { 401 struct posix_acl *acl; 402 int error; 403 404 if (!test_opt(inode->i_sb, POSIX_ACL)) 405 return -EOPNOTSUPP; 406 407 acl = ext4_get_acl(inode, type); 408 if (IS_ERR(acl)) 409 return PTR_ERR(acl); 410 if (acl == NULL) 411 return -ENODATA; 412 error = posix_acl_to_xattr(acl, buffer, size); 413 posix_acl_release(acl); 414 415 return error; 416 } 417 418 static int 419 ext4_xattr_get_acl_access(struct inode *inode, const char *name, 420 void *buffer, size_t size) 421 { 422 if (strcmp(name, "") != 0) 423 return -EINVAL; 424 return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size); 425 } 426 427 static int 428 ext4_xattr_get_acl_default(struct inode *inode, const char *name, 429 void *buffer, size_t size) 430 { 431 if (strcmp(name, "") != 0) 432 return -EINVAL; 433 return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size); 434 } 435 436 static int 437 ext4_xattr_set_acl(struct inode *inode, int type, const void *value, 438 size_t size) 439 { 440 handle_t *handle; 441 struct posix_acl *acl; 442 int error, retries = 0; 443 444 if (!test_opt(inode->i_sb, POSIX_ACL)) 445 return -EOPNOTSUPP; 446 if (!is_owner_or_cap(inode)) 447 return -EPERM; 448 449 if (value) { 450 acl = posix_acl_from_xattr(value, size); 451 if (IS_ERR(acl)) 452 return PTR_ERR(acl); 453 else if (acl) { 454 error = posix_acl_valid(acl); 455 if (error) 456 goto release_and_out; 457 } 458 } else 459 acl = NULL; 460 461 retry: 462 handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 463 if (IS_ERR(handle)) 464 return PTR_ERR(handle); 465 error = ext4_set_acl(handle, inode, type, acl); 466 ext4_journal_stop(handle); 467 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 468 goto retry; 469 470 release_and_out: 471 posix_acl_release(acl); 472 return error; 473 } 474 475 static int 476 ext4_xattr_set_acl_access(struct inode *inode, const char *name, 477 const void *value, size_t size, int flags) 478 { 479 if (strcmp(name, "") != 0) 480 return -EINVAL; 481 return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size); 482 } 483 484 static int 485 ext4_xattr_set_acl_default(struct inode *inode, const char *name, 486 const void *value, size_t size, int flags) 487 { 488 if (strcmp(name, "") != 0) 489 return -EINVAL; 490 return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size); 491 } 492 493 struct xattr_handler ext4_xattr_acl_access_handler = { 494 .prefix = POSIX_ACL_XATTR_ACCESS, 495 .list = ext4_xattr_list_acl_access, 496 .get = ext4_xattr_get_acl_access, 497 .set = ext4_xattr_set_acl_access, 498 }; 499 500 struct xattr_handler ext4_xattr_acl_default_handler = { 501 .prefix = POSIX_ACL_XATTR_DEFAULT, 502 .list = ext4_xattr_list_acl_default, 503 .get = ext4_xattr_get_acl_default, 504 .set = ext4_xattr_set_acl_default, 505 }; 506