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 break; 59 60 case ACL_USER: 61 value = (char *)value + sizeof(ext4_acl_entry); 62 if ((char *)value > end) 63 goto fail; 64 acl->a_entries[n].e_uid = 65 make_kuid(&init_user_ns, 66 le32_to_cpu(entry->e_id)); 67 break; 68 case ACL_GROUP: 69 value = (char *)value + sizeof(ext4_acl_entry); 70 if ((char *)value > end) 71 goto fail; 72 acl->a_entries[n].e_gid = 73 make_kgid(&init_user_ns, 74 le32_to_cpu(entry->e_id)); 75 break; 76 77 default: 78 goto fail; 79 } 80 } 81 if (value != end) 82 goto fail; 83 return acl; 84 85 fail: 86 posix_acl_release(acl); 87 return ERR_PTR(-EINVAL); 88 } 89 90 /* 91 * Convert from in-memory to filesystem representation. 92 */ 93 static void * 94 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size) 95 { 96 ext4_acl_header *ext_acl; 97 char *e; 98 size_t n; 99 100 *size = ext4_acl_size(acl->a_count); 101 ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count * 102 sizeof(ext4_acl_entry), GFP_NOFS); 103 if (!ext_acl) 104 return ERR_PTR(-ENOMEM); 105 ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION); 106 e = (char *)ext_acl + sizeof(ext4_acl_header); 107 for (n = 0; n < acl->a_count; n++) { 108 const struct posix_acl_entry *acl_e = &acl->a_entries[n]; 109 ext4_acl_entry *entry = (ext4_acl_entry *)e; 110 entry->e_tag = cpu_to_le16(acl_e->e_tag); 111 entry->e_perm = cpu_to_le16(acl_e->e_perm); 112 switch (acl_e->e_tag) { 113 case ACL_USER: 114 entry->e_id = cpu_to_le32( 115 from_kuid(&init_user_ns, acl_e->e_uid)); 116 e += sizeof(ext4_acl_entry); 117 break; 118 case ACL_GROUP: 119 entry->e_id = cpu_to_le32( 120 from_kgid(&init_user_ns, acl_e->e_gid)); 121 e += sizeof(ext4_acl_entry); 122 break; 123 124 case ACL_USER_OBJ: 125 case ACL_GROUP_OBJ: 126 case ACL_MASK: 127 case ACL_OTHER: 128 e += sizeof(ext4_acl_entry_short); 129 break; 130 131 default: 132 goto fail; 133 } 134 } 135 return (char *)ext_acl; 136 137 fail: 138 kfree(ext_acl); 139 return ERR_PTR(-EINVAL); 140 } 141 142 /* 143 * Inode operation get_posix_acl(). 144 * 145 * inode->i_mutex: don't care 146 */ 147 struct posix_acl * 148 ext4_get_acl(struct inode *inode, int type) 149 { 150 int name_index; 151 char *value = NULL; 152 struct posix_acl *acl; 153 int retval; 154 155 if (!test_opt(inode->i_sb, POSIX_ACL)) 156 return NULL; 157 158 acl = get_cached_acl(inode, type); 159 if (acl != ACL_NOT_CACHED) 160 return acl; 161 162 switch (type) { 163 case ACL_TYPE_ACCESS: 164 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 165 break; 166 case ACL_TYPE_DEFAULT: 167 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 168 break; 169 default: 170 BUG(); 171 } 172 retval = ext4_xattr_get(inode, name_index, "", NULL, 0); 173 if (retval > 0) { 174 value = kmalloc(retval, GFP_NOFS); 175 if (!value) 176 return ERR_PTR(-ENOMEM); 177 retval = ext4_xattr_get(inode, name_index, "", value, retval); 178 } 179 if (retval > 0) 180 acl = ext4_acl_from_disk(value, retval); 181 else if (retval == -ENODATA || retval == -ENOSYS) 182 acl = NULL; 183 else 184 acl = ERR_PTR(retval); 185 kfree(value); 186 187 if (!IS_ERR(acl)) 188 set_cached_acl(inode, type, acl); 189 190 return acl; 191 } 192 193 /* 194 * Set the access or default ACL of an inode. 195 * 196 * inode->i_mutex: down unless called from ext4_new_inode 197 */ 198 static int 199 ext4_set_acl(handle_t *handle, struct inode *inode, int type, 200 struct posix_acl *acl) 201 { 202 int name_index; 203 void *value = NULL; 204 size_t size = 0; 205 int error; 206 207 if (S_ISLNK(inode->i_mode)) 208 return -EOPNOTSUPP; 209 210 switch (type) { 211 case ACL_TYPE_ACCESS: 212 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; 213 if (acl) { 214 error = posix_acl_equiv_mode(acl, &inode->i_mode); 215 if (error < 0) 216 return error; 217 else { 218 inode->i_ctime = ext4_current_time(inode); 219 ext4_mark_inode_dirty(handle, inode); 220 if (error == 0) 221 acl = NULL; 222 } 223 } 224 break; 225 226 case ACL_TYPE_DEFAULT: 227 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; 228 if (!S_ISDIR(inode->i_mode)) 229 return acl ? -EACCES : 0; 230 break; 231 232 default: 233 return -EINVAL; 234 } 235 if (acl) { 236 value = ext4_acl_to_disk(acl, &size); 237 if (IS_ERR(value)) 238 return (int)PTR_ERR(value); 239 } 240 241 error = ext4_xattr_set_handle(handle, inode, name_index, "", 242 value, size, 0); 243 244 kfree(value); 245 if (!error) 246 set_cached_acl(inode, type, acl); 247 248 return error; 249 } 250 251 /* 252 * Initialize the ACLs of a new inode. Called from ext4_new_inode. 253 * 254 * dir->i_mutex: down 255 * inode->i_mutex: up (access to inode is still exclusive) 256 */ 257 int 258 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 259 { 260 struct posix_acl *acl = NULL; 261 int error = 0; 262 263 if (!S_ISLNK(inode->i_mode)) { 264 if (test_opt(dir->i_sb, POSIX_ACL)) { 265 acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); 266 if (IS_ERR(acl)) 267 return PTR_ERR(acl); 268 } 269 if (!acl) 270 inode->i_mode &= ~current_umask(); 271 } 272 if (test_opt(inode->i_sb, POSIX_ACL) && acl) { 273 if (S_ISDIR(inode->i_mode)) { 274 error = ext4_set_acl(handle, inode, 275 ACL_TYPE_DEFAULT, acl); 276 if (error) 277 goto cleanup; 278 } 279 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode); 280 if (error < 0) 281 return error; 282 283 if (error > 0) { 284 /* This is an extended ACL */ 285 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); 286 } 287 } 288 cleanup: 289 posix_acl_release(acl); 290 return error; 291 } 292 293 /* 294 * Does chmod for an inode that may have an Access Control List. The 295 * inode->i_mode field must be updated to the desired value by the caller 296 * before calling this function. 297 * Returns 0 on success, or a negative error number. 298 * 299 * We change the ACL rather than storing some ACL entries in the file 300 * mode permission bits (which would be more efficient), because that 301 * would break once additional permissions (like ACL_APPEND, ACL_DELETE 302 * for directories) are added. There are no more bits available in the 303 * file mode. 304 * 305 * inode->i_mutex: down 306 */ 307 int 308 ext4_acl_chmod(struct inode *inode) 309 { 310 struct posix_acl *acl; 311 handle_t *handle; 312 int retries = 0; 313 int error; 314 315 316 if (S_ISLNK(inode->i_mode)) 317 return -EOPNOTSUPP; 318 if (!test_opt(inode->i_sb, POSIX_ACL)) 319 return 0; 320 acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); 321 if (IS_ERR(acl) || !acl) 322 return PTR_ERR(acl); 323 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode); 324 if (error) 325 return error; 326 retry: 327 handle = ext4_journal_start(inode, EXT4_HT_XATTR, 328 ext4_jbd2_credits_xattr(inode)); 329 if (IS_ERR(handle)) { 330 error = PTR_ERR(handle); 331 ext4_std_error(inode->i_sb, error); 332 goto out; 333 } 334 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl); 335 ext4_journal_stop(handle); 336 if (error == -ENOSPC && 337 ext4_should_retry_alloc(inode->i_sb, &retries)) 338 goto retry; 339 out: 340 posix_acl_release(acl); 341 return error; 342 } 343 344 /* 345 * Extended attribute handlers 346 */ 347 static size_t 348 ext4_xattr_list_acl_access(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_ACCESS); 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_ACCESS, size); 357 return size; 358 } 359 360 static size_t 361 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len, 362 const char *name, size_t name_len, int type) 363 { 364 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); 365 366 if (!test_opt(dentry->d_sb, POSIX_ACL)) 367 return 0; 368 if (list && size <= list_len) 369 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); 370 return size; 371 } 372 373 static int 374 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer, 375 size_t size, int type) 376 { 377 struct posix_acl *acl; 378 int error; 379 380 if (strcmp(name, "") != 0) 381 return -EINVAL; 382 if (!test_opt(dentry->d_sb, POSIX_ACL)) 383 return -EOPNOTSUPP; 384 385 acl = ext4_get_acl(dentry->d_inode, type); 386 if (IS_ERR(acl)) 387 return PTR_ERR(acl); 388 if (acl == NULL) 389 return -ENODATA; 390 error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size); 391 posix_acl_release(acl); 392 393 return error; 394 } 395 396 static int 397 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value, 398 size_t size, int flags, int type) 399 { 400 struct inode *inode = dentry->d_inode; 401 handle_t *handle; 402 struct posix_acl *acl; 403 int error, retries = 0; 404 405 if (strcmp(name, "") != 0) 406 return -EINVAL; 407 if (!test_opt(inode->i_sb, POSIX_ACL)) 408 return -EOPNOTSUPP; 409 if (!inode_owner_or_capable(inode)) 410 return -EPERM; 411 412 if (value) { 413 acl = posix_acl_from_xattr(&init_user_ns, value, size); 414 if (IS_ERR(acl)) 415 return PTR_ERR(acl); 416 else if (acl) { 417 error = posix_acl_valid(acl); 418 if (error) 419 goto release_and_out; 420 } 421 } else 422 acl = NULL; 423 424 retry: 425 handle = ext4_journal_start(inode, EXT4_HT_XATTR, 426 ext4_jbd2_credits_xattr(inode)); 427 if (IS_ERR(handle)) { 428 error = PTR_ERR(handle); 429 goto release_and_out; 430 } 431 error = ext4_set_acl(handle, inode, type, acl); 432 ext4_journal_stop(handle); 433 if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 434 goto retry; 435 436 release_and_out: 437 posix_acl_release(acl); 438 return error; 439 } 440 441 const struct xattr_handler ext4_xattr_acl_access_handler = { 442 .prefix = POSIX_ACL_XATTR_ACCESS, 443 .flags = ACL_TYPE_ACCESS, 444 .list = ext4_xattr_list_acl_access, 445 .get = ext4_xattr_get_acl, 446 .set = ext4_xattr_set_acl, 447 }; 448 449 const struct xattr_handler ext4_xattr_acl_default_handler = { 450 .prefix = POSIX_ACL_XATTR_DEFAULT, 451 .flags = ACL_TYPE_DEFAULT, 452 .list = ext4_xattr_list_acl_default, 453 .get = ext4_xattr_get_acl, 454 .set = ext4_xattr_set_acl, 455 }; 456