1/* 2 * linux/fs/ext3/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 <linux/ext3_jbd.h> 13#include <linux/ext3_fs.h> 14#include "xattr.h" 15#include "acl.h" 16 17/* 18 * Convert from filesystem to in-memory representation. 19 */ 20static struct posix_acl * 21ext3_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(ext3_acl_header)) 30 return ERR_PTR(-EINVAL); 31 if (((ext3_acl_header *)value)->a_version != 32 cpu_to_le32(EXT3_ACL_VERSION)) 33 return ERR_PTR(-EINVAL); 34 value = (char *)value + sizeof(ext3_acl_header); 35 count = ext3_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 ext3_acl_entry *entry = 45 (ext3_acl_entry *)value; 46 if ((char *)value + sizeof(ext3_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 switch(acl->a_entries[n].e_tag) { 51 case ACL_USER_OBJ: 52 case ACL_GROUP_OBJ: 53 case ACL_MASK: 54 case ACL_OTHER: 55 value = (char *)value + 56 sizeof(ext3_acl_entry_short); 57 acl->a_entries[n].e_id = ACL_UNDEFINED_ID; 58 break; 59 60 case ACL_USER: 61 case ACL_GROUP: 62 value = (char *)value + sizeof(ext3_acl_entry); 63 if ((char *)value > end) 64 goto fail; 65 acl->a_entries[n].e_id = 66 le32_to_cpu(entry->e_id); 67 break; 68 69 default: 70 goto fail; 71 } 72 } 73 if (value != end) 74 goto fail; 75 return acl; 76 77fail: 78 posix_acl_release(acl); 79 return ERR_PTR(-EINVAL); 80} 81 82/* 83 * Convert from in-memory to filesystem representation. 84 */ 85static void * 86ext3_acl_to_disk(const struct posix_acl *acl, size_t *size) 87{ 88 ext3_acl_header *ext_acl; 89 char *e; 90 size_t n; 91 92 *size = ext3_acl_size(acl->a_count); 93 ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count * 94 sizeof(ext3_acl_entry), GFP_NOFS); 95 if (!ext_acl) 96 return ERR_PTR(-ENOMEM); 97 ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION); 98 e = (char *)ext_acl + sizeof(ext3_acl_header); 99 for (n=0; n < acl->a_count; n++) { 100 ext3_acl_entry *entry = (ext3_acl_entry *)e; 101 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag); 102 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm); 103 switch(acl->a_entries[n].e_tag) { 104 case ACL_USER: 105 case ACL_GROUP: 106 entry->e_id = 107 cpu_to_le32(acl->a_entries[n].e_id); 108 e += sizeof(ext3_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(ext3_acl_entry_short); 116 break; 117 118 default: 119 goto fail; 120 } 121 } 122 return (char *)ext_acl; 123 124fail: 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 */ 134static struct posix_acl * 135ext3_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 = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS; 152 break; 153 case ACL_TYPE_DEFAULT: 154 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT; 155 break; 156 default: 157 BUG(); 158 } 159 160 retval = ext3_xattr_get(inode, name_index, "", NULL, 0); 161 if (retval > 0) { 162 value = kmalloc(retval, GFP_NOFS); 163 if (!value) 164 return ERR_PTR(-ENOMEM); 165 retval = ext3_xattr_get(inode, name_index, "", value, retval); 166 } 167 if (retval > 0) 168 acl = ext3_acl_from_disk(value, retval); 169 else if (retval == -ENODATA || retval == -ENOSYS) 170 acl = NULL; 171 else 172 acl = ERR_PTR(retval); 173 kfree(value); 174 175 if (!IS_ERR(acl)) 176 set_cached_acl(inode, type, acl); 177 178 return acl; 179} 180 181/* 182 * Set the access or default ACL of an inode. 183 * 184 * inode->i_mutex: down unless called from ext3_new_inode 185 */ 186static int 187ext3_set_acl(handle_t *handle, struct inode *inode, int type, 188 struct posix_acl *acl) 189{ 190 int name_index; 191 void *value = NULL; 192 size_t size = 0; 193 int error; 194 195 if (S_ISLNK(inode->i_mode)) 196 return -EOPNOTSUPP; 197 198 switch(type) { 199 case ACL_TYPE_ACCESS: 200 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS; 201 if (acl) { 202 mode_t mode = inode->i_mode; 203 error = posix_acl_equiv_mode(acl, &mode); 204 if (error < 0) 205 return error; 206 else { 207 inode->i_mode = mode; 208 inode->i_ctime = CURRENT_TIME_SEC; 209 ext3_mark_inode_dirty(handle, inode); 210 if (error == 0) 211 acl = NULL; 212 } 213 } 214 break; 215 216 case ACL_TYPE_DEFAULT: 217 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT; 218 if (!S_ISDIR(inode->i_mode)) 219 return acl ? -EACCES : 0; 220 break; 221 222 default: 223 return -EINVAL; 224 } 225 if (acl) { 226 value = ext3_acl_to_disk(acl, &size); 227 if (IS_ERR(value)) 228 return (int)PTR_ERR(value); 229 } 230 231 error = ext3_xattr_set_handle(handle, inode, name_index, "", 232 value, size, 0); 233 234 kfree(value); 235 236 if (!error) 237 set_cached_acl(inode, type, acl); 238 239 return error; 240} 241 242int 243ext3_check_acl(struct inode *inode, int mask) 244{ 245 struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS); 246 247 if (IS_ERR(acl)) 248 return PTR_ERR(acl); 249 if (acl) { 250 int error = posix_acl_permission(inode, acl, mask); 251 posix_acl_release(acl); 252 return error; 253 } 254 255 return -EAGAIN; 256} 257 258/* 259 * Initialize the ACLs of a new inode. Called from ext3_new_inode. 260 * 261 * dir->i_mutex: down 262 * inode->i_mutex: up (access to inode is still exclusive) 263 */ 264int 265ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) 266{ 267 struct posix_acl *acl = NULL; 268 int error = 0; 269 270 if (!S_ISLNK(inode->i_mode)) { 271 if (test_opt(dir->i_sb, POSIX_ACL)) { 272 acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT); 273 if (IS_ERR(acl)) 274 return PTR_ERR(acl); 275 } 276 if (!acl) 277 inode->i_mode &= ~current_umask(); 278 } 279 if (test_opt(inode->i_sb, POSIX_ACL) && acl) { 280 struct posix_acl *clone; 281 mode_t mode; 282 283 if (S_ISDIR(inode->i_mode)) { 284 error = ext3_set_acl(handle, inode, 285 ACL_TYPE_DEFAULT, acl); 286 if (error) 287 goto cleanup; 288 } 289 clone = posix_acl_clone(acl, GFP_NOFS); 290 error = -ENOMEM; 291 if (!clone) 292 goto cleanup; 293 294 mode = inode->i_mode; 295 error = posix_acl_create_masq(clone, &mode); 296 if (error >= 0) { 297 inode->i_mode = mode; 298 if (error > 0) { 299 /* This is an extended ACL */ 300 error = ext3_set_acl(handle, inode, 301 ACL_TYPE_ACCESS, clone); 302 } 303 } 304 posix_acl_release(clone); 305 } 306cleanup: 307 posix_acl_release(acl); 308 return error; 309} 310 311/* 312 * Does chmod for an inode that may have an Access Control List. The 313 * inode->i_mode field must be updated to the desired value by the caller 314 * before calling this function. 315 * Returns 0 on success, or a negative error number. 316 * 317 * We change the ACL rather than storing some ACL entries in the file 318 * mode permission bits (which would be more efficient), because that 319 * would break once additional permissions (like ACL_APPEND, ACL_DELETE 320 * for directories) are added. There are no more bits available in the 321 * file mode. 322 * 323 * inode->i_mutex: down 324 */ 325int 326ext3_acl_chmod(struct inode *inode) 327{ 328 struct posix_acl *acl, *clone; 329 int error; 330 331 if (S_ISLNK(inode->i_mode)) 332 return -EOPNOTSUPP; 333 if (!test_opt(inode->i_sb, POSIX_ACL)) 334 return 0; 335 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS); 336 if (IS_ERR(acl) || !acl) 337 return PTR_ERR(acl); 338 clone = posix_acl_clone(acl, GFP_KERNEL); 339 posix_acl_release(acl); 340 if (!clone) 341 return -ENOMEM; 342 error = posix_acl_chmod_masq(clone, inode->i_mode); 343 if (!error) { 344 handle_t *handle; 345 int retries = 0; 346 347 retry: 348 handle = ext3_journal_start(inode, 349 EXT3_DATA_TRANS_BLOCKS(inode->i_sb)); 350 if (IS_ERR(handle)) { 351 error = PTR_ERR(handle); 352 ext3_std_error(inode->i_sb, error); 353 goto out; 354 } 355 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone); 356 ext3_journal_stop(handle); 357 if (error == -ENOSPC && 358 ext3_should_retry_alloc(inode->i_sb, &retries)) 359 goto retry; 360 } 361out: 362 posix_acl_release(clone); 363 return error; 364} 365 366/* 367 * Extended attribute handlers 368 */ 369static size_t 370ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len, 371 const char *name, size_t name_len, int type) 372{ 373 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); 374 375 if (!test_opt(dentry->d_sb, POSIX_ACL)) 376 return 0; 377 if (list && size <= list_len) 378 memcpy(list, POSIX_ACL_XATTR_ACCESS, size); 379 return size; 380} 381 382static size_t 383ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len, 384 const char *name, size_t name_len, int type) 385{ 386 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); 387 388 if (!test_opt(dentry->d_sb, POSIX_ACL)) 389 return 0; 390 if (list && size <= list_len) 391 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); 392 return size; 393} 394 395static int 396ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer, 397 size_t size, int type) 398{ 399 struct posix_acl *acl; 400 int error; 401 402 if (strcmp(name, "") != 0) 403 return -EINVAL; 404 if (!test_opt(dentry->d_sb, POSIX_ACL)) 405 return -EOPNOTSUPP; 406 407 acl = ext3_get_acl(dentry->d_inode, type); 408 if (IS_ERR(acl)) 409 return PTR_ERR(acl); 410 if (acl == NULL) 411 return -ENODATA; 412 error = posix_acl_to_xattr(acl, buffer, size); 413 posix_acl_release(acl); 414 415 return error; 416} 417 418static int 419ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value, 420 size_t size, int flags, int type) 421{ 422 struct inode *inode = dentry->d_inode; 423 handle_t *handle; 424 struct posix_acl *acl; 425 int error, retries = 0; 426 427 if (strcmp(name, "") != 0) 428 return -EINVAL; 429 if (!test_opt(inode->i_sb, POSIX_ACL)) 430 return -EOPNOTSUPP; 431 if (!is_owner_or_cap(inode)) 432 return -EPERM; 433 434 if (value) { 435 acl = posix_acl_from_xattr(value, size); 436 if (IS_ERR(acl)) 437 return PTR_ERR(acl); 438 else if (acl) { 439 error = posix_acl_valid(acl); 440 if (error) 441 goto release_and_out; 442 } 443 } else 444 acl = NULL; 445 446retry: 447 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb)); 448 if (IS_ERR(handle)) 449 return PTR_ERR(handle); 450 error = ext3_set_acl(handle, inode, type, acl); 451 ext3_journal_stop(handle); 452 if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries)) 453 goto retry; 454 455release_and_out: 456 posix_acl_release(acl); 457 return error; 458} 459 460const struct xattr_handler ext3_xattr_acl_access_handler = { 461 .prefix = POSIX_ACL_XATTR_ACCESS, 462 .flags = ACL_TYPE_ACCESS, 463 .list = ext3_xattr_list_acl_access, 464 .get = ext3_xattr_get_acl, 465 .set = ext3_xattr_set_acl, 466}; 467 468const struct xattr_handler ext3_xattr_acl_default_handler = { 469 .prefix = POSIX_ACL_XATTR_DEFAULT, 470 .flags = ACL_TYPE_DEFAULT, 471 .list = ext3_xattr_list_acl_default, 472 .get = ext3_xattr_get_acl, 473 .set = ext3_xattr_set_acl, 474}; 475