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