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