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 inode->i_ctime = ext4_current_time(inode); 208 ext4_mark_inode_dirty(handle, inode); 209 if (error == 0) 210 acl = NULL; 211 } 212 } 213 break; 214 215 case ACL_TYPE_DEFAULT: 216 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 217 if (!S_ISDIR(inode->i_mode)) 218 return acl ? -EACCES : 0; 219 break; 220 221 default: 222 return -EINVAL; 223 } 224 if (acl) { 225 value = ext4_acl_to_disk(acl, &size); 226 if (IS_ERR(value)) 227 return (int)PTR_ERR(value); 228 } 229 230 error = ext4_xattr_set_handle(handle, inode, name_index, "", 231 value, size, 0); 232 233 kfree(value); 234 if (!error) 235 set_cached_acl(inode, type, acl); 236 237 return error; 238 } 239 240 int 241 ext4_check_acl(struct inode *inode, int mask, unsigned int flags) 242 { 243 struct posix_acl *acl; 244 245 if (flags & IPERM_FLAG_RCU) { 246 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS)) 247 return -ECHILD; 248 return -EAGAIN; 249 } 250 251 acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 252 if (IS_ERR(acl)) 253 return PTR_ERR(acl); 254 if (acl) { 255 int error = posix_acl_permission(inode, acl, mask); 256 posix_acl_release(acl); 257 return error; 258 } 259 260 return -EAGAIN; 261 } 262 263 /* 264 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 265 * 266 * dir->i_mutex: down 267 * inode->i_mutex: up (access to inode is still exclusive) 268 */ 269 int 270 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 271 { 272 struct posix_acl *acl = NULL; 273 int error = 0; 274 275 if (!S_ISLNK(inode->i_mode)) { 276 if (test_opt(dir->i_sb, POSIX_ACL)) { 277 acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); 278 if (IS_ERR(acl)) 279 return PTR_ERR(acl); 280 } 281 if (!acl) 282 inode->i_mode &= ~current_umask(); 283 } 284 if (test_opt(inode->i_sb, POSIX_ACL) && acl) { 285 struct posix_acl *clone; 286 mode_t mode; 287 288 if (S_ISDIR(inode->i_mode)) { 289 error = ext4_set_acl(handle, inode, 290 ACL_TYPE_DEFAULT, acl); 291 if (error) 292 goto cleanup; 293 } 294 clone = posix_acl_clone(acl, GFP_NOFS); 295 error = -ENOMEM; 296 if (!clone) 297 goto cleanup; 298 299 mode = inode->i_mode; 300 error = posix_acl_create_masq(clone, &mode); 301 if (error >= 0) { 302 inode->i_mode = mode; 303 if (error > 0) { 304 /* This is an extended ACL */ 305 error = ext4_set_acl(handle, inode, 306 ACL_TYPE_ACCESS, clone); 307 } 308 } 309 posix_acl_release(clone); 310 } 311 cleanup: 312 posix_acl_release(acl); 313 return error; 314 } 315 316 /* 317 * Does chmod for an inode that may have an Access Control List. The 318 * inode->i_mode field must be updated to the desired value by the caller 319 * before calling this function. 320 * Returns 0 on success, or a negative error number. 321 * 322 * We change the ACL rather than storing some ACL entries in the file 323 * mode permission bits (which would be more efficient), because that 324 * would break once additional permissions (like ACL_APPEND, ACL_DELETE 325 * for directories) are added. There are no more bits available in the 326 * file mode. 327 * 328 * inode->i_mutex: down 329 */ 330 int 331 ext4_acl_chmod(struct inode *inode) 332 { 333 struct posix_acl *acl, *clone; 334 int error; 335 336 if (S_ISLNK(inode->i_mode)) 337 return -EOPNOTSUPP; 338 if (!test_opt(inode->i_sb, POSIX_ACL)) 339 return 0; 340 acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 341 if (IS_ERR(acl) || !acl) 342 return PTR_ERR(acl); 343 clone = posix_acl_clone(acl, GFP_KERNEL); 344 posix_acl_release(acl); 345 if (!clone) 346 return -ENOMEM; 347 error = posix_acl_chmod_masq(clone, inode->i_mode); 348 if (!error) { 349 handle_t *handle; 350 int retries = 0; 351 352 retry: 353 handle = ext4_journal_start(inode, 354 EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 355 if (IS_ERR(handle)) { 356 error = PTR_ERR(handle); 357 ext4_std_error(inode->i_sb, error); 358 goto out; 359 } 360 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone); 361 ext4_journal_stop(handle); 362 if (error == -ENOSPC && 363 ext4_should_retry_alloc(inode->i_sb, &retries)) 364 goto retry; 365 } 366 out: 367 posix_acl_release(clone); 368 return error; 369 } 370 371 /* 372 * Extended attribute handlers 373 */ 374 static size_t 375 ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len, 376 const char *name, size_t name_len, int type) 377 { 378 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); 379 380 if (!test_opt(dentry->d_sb, POSIX_ACL)) 381 return 0; 382 if (list && size <= list_len) 383 memcpy(list, POSIX_ACL_XATTR_ACCESS, size); 384 return size; 385 } 386 387 static size_t 388 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len, 389 const char *name, size_t name_len, int type) 390 { 391 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); 392 393 if (!test_opt(dentry->d_sb, POSIX_ACL)) 394 return 0; 395 if (list && size <= list_len) 396 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); 397 return size; 398 } 399 400 static int 401 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer, 402 size_t size, int type) 403 { 404 struct posix_acl *acl; 405 int error; 406 407 if (strcmp(name, "") != 0) 408 return -EINVAL; 409 if (!test_opt(dentry->d_sb, POSIX_ACL)) 410 return -EOPNOTSUPP; 411 412 acl = ext4_get_acl(dentry->d_inode, type); 413 if (IS_ERR(acl)) 414 return PTR_ERR(acl); 415 if (acl == NULL) 416 return -ENODATA; 417 error = posix_acl_to_xattr(acl, buffer, size); 418 posix_acl_release(acl); 419 420 return error; 421 } 422 423 static int 424 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value, 425 size_t size, int flags, int type) 426 { 427 struct inode *inode = dentry->d_inode; 428 handle_t *handle; 429 struct posix_acl *acl; 430 int error, retries = 0; 431 432 if (strcmp(name, "") != 0) 433 return -EINVAL; 434 if (!test_opt(inode->i_sb, POSIX_ACL)) 435 return -EOPNOTSUPP; 436 if (!is_owner_or_cap(inode)) 437 return -EPERM; 438 439 if (value) { 440 acl = posix_acl_from_xattr(value, size); 441 if (IS_ERR(acl)) 442 return PTR_ERR(acl); 443 else if (acl) { 444 error = posix_acl_valid(acl); 445 if (error) 446 goto release_and_out; 447 } 448 } else 449 acl = NULL; 450 451 retry: 452 handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 453 if (IS_ERR(handle)) 454 return PTR_ERR(handle); 455 error = ext4_set_acl(handle, inode, type, acl); 456 ext4_journal_stop(handle); 457 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 458 goto retry; 459 460 release_and_out: 461 posix_acl_release(acl); 462 return error; 463 } 464 465 const struct xattr_handler ext4_xattr_acl_access_handler = { 466 .prefix = POSIX_ACL_XATTR_ACCESS, 467 .flags = ACL_TYPE_ACCESS, 468 .list = ext4_xattr_list_acl_access, 469 .get = ext4_xattr_get_acl, 470 .set = ext4_xattr_set_acl, 471 }; 472 473 const struct xattr_handler ext4_xattr_acl_default_handler = { 474 .prefix = POSIX_ACL_XATTR_DEFAULT, 475 .flags = ACL_TYPE_DEFAULT, 476 .list = ext4_xattr_list_acl_default, 477 .get = ext4_xattr_get_acl, 478 .set = ext4_xattr_set_acl, 479 }; 480