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 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 error = posix_acl_equiv_mode(acl, &inode->i_mode); 202 if (error < 0) 203 return error; 204 else { 205 inode->i_ctime = ext4_current_time(inode); 206 ext4_mark_inode_dirty(handle, inode); 207 if (error == 0) 208 acl = NULL; 209 } 210 } 211 break; 212 213 case ACL_TYPE_DEFAULT: 214 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 215 if (!S_ISDIR(inode->i_mode)) 216 return acl ? -EACCES : 0; 217 break; 218 219 default: 220 return -EINVAL; 221 } 222 if (acl) { 223 value = ext4_acl_to_disk(acl, &size); 224 if (IS_ERR(value)) 225 return (int)PTR_ERR(value); 226 } 227 228 error = ext4_xattr_set_handle(handle, inode, name_index, "", 229 value, size, 0); 230 231 kfree(value); 232 if (!error) 233 set_cached_acl(inode, type, acl); 234 235 return error; 236 } 237 238 /* 239 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 240 * 241 * dir->i_mutex: down 242 * inode->i_mutex: up (access to inode is still exclusive) 243 */ 244 int 245 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 246 { 247 struct posix_acl *acl = NULL; 248 int error = 0; 249 250 if (!S_ISLNK(inode->i_mode)) { 251 if (test_opt(dir->i_sb, POSIX_ACL)) { 252 acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); 253 if (IS_ERR(acl)) 254 return PTR_ERR(acl); 255 } 256 if (!acl) 257 inode->i_mode &= ~current_umask(); 258 } 259 if (test_opt(inode->i_sb, POSIX_ACL) && acl) { 260 if (S_ISDIR(inode->i_mode)) { 261 error = ext4_set_acl(handle, inode, 262 ACL_TYPE_DEFAULT, acl); 263 if (error) 264 goto cleanup; 265 } 266 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode); 267 if (error < 0) 268 return error; 269 270 if (error > 0) { 271 /* This is an extended ACL */ 272 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); 273 } 274 } 275 cleanup: 276 posix_acl_release(acl); 277 return error; 278 } 279 280 /* 281 * Does chmod for an inode that may have an Access Control List. The 282 * inode->i_mode field must be updated to the desired value by the caller 283 * before calling this function. 284 * Returns 0 on success, or a negative error number. 285 * 286 * We change the ACL rather than storing some ACL entries in the file 287 * mode permission bits (which would be more efficient), because that 288 * would break once additional permissions (like ACL_APPEND, ACL_DELETE 289 * for directories) are added. There are no more bits available in the 290 * file mode. 291 * 292 * inode->i_mutex: down 293 */ 294 int 295 ext4_acl_chmod(struct inode *inode) 296 { 297 struct posix_acl *acl; 298 handle_t *handle; 299 int retries = 0; 300 int error; 301 302 303 if (S_ISLNK(inode->i_mode)) 304 return -EOPNOTSUPP; 305 if (!test_opt(inode->i_sb, POSIX_ACL)) 306 return 0; 307 acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 308 if (IS_ERR(acl) || !acl) 309 return PTR_ERR(acl); 310 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode); 311 if (error) 312 return error; 313 retry: 314 handle = ext4_journal_start(inode, 315 EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 316 if (IS_ERR(handle)) { 317 error = PTR_ERR(handle); 318 ext4_std_error(inode->i_sb, error); 319 goto out; 320 } 321 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); 322 ext4_journal_stop(handle); 323 if (error == -ENOSPC && 324 ext4_should_retry_alloc(inode->i_sb, &retries)) 325 goto retry; 326 out: 327 posix_acl_release(acl); 328 return error; 329 } 330 331 /* 332 * Extended attribute handlers 333 */ 334 static size_t 335 ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len, 336 const char *name, size_t name_len, int type) 337 { 338 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); 339 340 if (!test_opt(dentry->d_sb, POSIX_ACL)) 341 return 0; 342 if (list && size <= list_len) 343 memcpy(list, POSIX_ACL_XATTR_ACCESS, size); 344 return size; 345 } 346 347 static size_t 348 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len, 349 const char *name, size_t name_len, int type) 350 { 351 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); 352 353 if (!test_opt(dentry->d_sb, POSIX_ACL)) 354 return 0; 355 if (list && size <= list_len) 356 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); 357 return size; 358 } 359 360 static int 361 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer, 362 size_t size, int type) 363 { 364 struct posix_acl *acl; 365 int error; 366 367 if (strcmp(name, "") != 0) 368 return -EINVAL; 369 if (!test_opt(dentry->d_sb, POSIX_ACL)) 370 return -EOPNOTSUPP; 371 372 acl = ext4_get_acl(dentry->d_inode, type); 373 if (IS_ERR(acl)) 374 return PTR_ERR(acl); 375 if (acl == NULL) 376 return -ENODATA; 377 error = posix_acl_to_xattr(acl, buffer, size); 378 posix_acl_release(acl); 379 380 return error; 381 } 382 383 static int 384 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value, 385 size_t size, int flags, int type) 386 { 387 struct inode *inode = dentry->d_inode; 388 handle_t *handle; 389 struct posix_acl *acl; 390 int error, retries = 0; 391 392 if (strcmp(name, "") != 0) 393 return -EINVAL; 394 if (!test_opt(inode->i_sb, POSIX_ACL)) 395 return -EOPNOTSUPP; 396 if (!inode_owner_or_capable(inode)) 397 return -EPERM; 398 399 if (value) { 400 acl = posix_acl_from_xattr(value, size); 401 if (IS_ERR(acl)) 402 return PTR_ERR(acl); 403 else if (acl) { 404 error = posix_acl_valid(acl); 405 if (error) 406 goto release_and_out; 407 } 408 } else 409 acl = NULL; 410 411 retry: 412 handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); 413 if (IS_ERR(handle)) 414 return PTR_ERR(handle); 415 error = ext4_set_acl(handle, inode, type, acl); 416 ext4_journal_stop(handle); 417 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 418 goto retry; 419 420 release_and_out: 421 posix_acl_release(acl); 422 return error; 423 } 424 425 const struct xattr_handler ext4_xattr_acl_access_handler = { 426 .prefix = POSIX_ACL_XATTR_ACCESS, 427 .flags = ACL_TYPE_ACCESS, 428 .list = ext4_xattr_list_acl_access, 429 .get = ext4_xattr_get_acl, 430 .set = ext4_xattr_set_acl, 431 }; 432 433 const struct xattr_handler ext4_xattr_acl_default_handler = { 434 .prefix = POSIX_ACL_XATTR_DEFAULT, 435 .flags = ACL_TYPE_DEFAULT, 436 .list = ext4_xattr_list_acl_default, 437 .get = ext4_xattr_get_acl, 438 .set = ext4_xattr_set_acl, 439 }; 440