fs/ext3/acl.c

   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/fs.h>
  11 #include <linux/namei.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  */
  20 static struct posix_acl *
  21 ext3_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_KERNEL);
  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
  77 fail:
  78         posix_acl_release(acl);
  79         return ERR_PTR(-EINVAL);
  80 }
  81
  82 /*
  83  * Convert from in-memory to filesystem representation.
  84  */
  85 static void *
  86 ext3_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 = (ext3_acl_header *)kmalloc(sizeof(ext3_acl_header) +
  94                 acl->a_count * sizeof(ext3_acl_entry), GFP_KERNEL);
  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
 124 fail:
 125         kfree(ext_acl);
 126         return ERR_PTR(-EINVAL);
 127 }
 128
 129 static inline struct posix_acl *
 130 ext3_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 131 {
 132         struct posix_acl *acl = EXT3_ACL_NOT_CACHED;
 133
 134         spin_lock(&inode->i_lock);
 135         if (*i_acl != EXT3_ACL_NOT_CACHED)
 136                 acl = posix_acl_dup(*i_acl);
 137         spin_unlock(&inode->i_lock);
 138
 139         return acl;
 140 }
 141
 142 static inline void
 143 ext3_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 144                   struct posix_acl *acl)
 145 {
 146         spin_lock(&inode->i_lock);
 147         if (*i_acl != EXT3_ACL_NOT_CACHED)
 148                 posix_acl_release(*i_acl);
 149         *i_acl = posix_acl_dup(acl);
 150         spin_unlock(&inode->i_lock);
 151 }
 152
 153 /*
 154  * Inode operation get_posix_acl().
 155  *
 156  * inode->i_sem: don't care
 157  */
 158 static struct posix_acl *
 159 ext3_get_acl(struct inode *inode, int type)
 160 {
 161         struct ext3_inode_info *ei = EXT3_I(inode);
 162         int name_index;
 163         char *value = NULL;
 164         struct posix_acl *acl;
 165         int retval;
 166
 167         if (!test_opt(inode->i_sb, POSIX_ACL))
 168                 return NULL;
 169
 170         switch(type) {
 171                 case ACL_TYPE_ACCESS:
 172                         acl = ext3_iget_acl(inode, &ei->i_acl);
 173                         if (acl != EXT3_ACL_NOT_CACHED)
 174                                 return acl;
 175                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 176                         break;
 177
 178                 case ACL_TYPE_DEFAULT:
 179                         acl = ext3_iget_acl(inode, &ei->i_default_acl);
 180                         if (acl != EXT3_ACL_NOT_CACHED)
 181                                 return acl;
 182                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 183                         break;
 184
 185                 default:
 186                         return ERR_PTR(-EINVAL);
 187         }
 188         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 189         if (retval > 0) {
 190                 value = kmalloc(retval, GFP_KERNEL);
 191                 if (!value)
 192                         return ERR_PTR(-ENOMEM);
 193                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 194         }
 195         if (retval > 0)
 196                 acl = ext3_acl_from_disk(value, retval);
 197         else if (retval == -ENODATA || retval == -ENOSYS)
 198                 acl = NULL;
 199         else
 200                 acl = ERR_PTR(retval);
 201         if (value)
 202                 kfree(value);
 203
 204         if (!IS_ERR(acl)) {
 205                 switch(type) {
 206                         case ACL_TYPE_ACCESS:
 207                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 208                                 break;
 209
 210                         case ACL_TYPE_DEFAULT:
 211                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 212                                 break;
 213                 }
 214         }
 215         return acl;
 216 }
 217
 218 /*
 219  * Set the access or default ACL of an inode.
 220  *
 221  * inode->i_sem: down unless called from ext3_new_inode
 222  */
 223 static int
 224 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 225              struct posix_acl *acl)
 226 {
 227         struct ext3_inode_info *ei = EXT3_I(inode);
 228         int name_index;
 229         void *value = NULL;
 230         size_t size;
 231         int error;
 232
 233         if (S_ISLNK(inode->i_mode))
 234                 return -EOPNOTSUPP;
 235
 236         switch(type) {
 237                 case ACL_TYPE_ACCESS:
 238                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 239                         if (acl) {
 240                                 mode_t mode = inode->i_mode;
 241                                 error = posix_acl_equiv_mode(acl, &mode);
 242                                 if (error < 0)
 243                                         return error;
 244                                 else {
 245                                         inode->i_mode = mode;
 246                                         ext3_mark_inode_dirty(handle, inode);
 247                                         if (error == 0)
 248                                                 acl = NULL;
 249                                 }
 250                         }
 251                         break;
 252
 253                 case ACL_TYPE_DEFAULT:
 254                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 255                         if (!S_ISDIR(inode->i_mode))
 256                                 return acl ? -EACCES : 0;
 257                         break;
 258
 259                 default:
 260                         return -EINVAL;
 261         }
 262         if (acl) {
 263                 if (acl->a_count > EXT3_ACL_MAX_ENTRIES)
 264                         return -EINVAL;
 265                 value = ext3_acl_to_disk(acl, &size);
 266                 if (IS_ERR(value))
 267                         return (int)PTR_ERR(value);
 268         }
 269
 270         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 271                                       value, size, 0);
 272
 273         if (value)
 274                 kfree(value);
 275         if (!error) {
 276                 switch(type) {
 277                         case ACL_TYPE_ACCESS:
 278                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 279                                 break;
 280
 281                         case ACL_TYPE_DEFAULT:
 282                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 283                                 break;
 284                 }
 285         }
 286         return error;
 287 }
 288
 289 /*
 290  * Inode operation permission().
 291  *
 292  * inode->i_sem: don't care
 293  */
 294 int
 295 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 296 {
 297         int mode = inode->i_mode;
 298
 299         /* Nobody gets write access to a read-only fs */
 300         if ((mask & MAY_WRITE) && (IS_RDONLY(inode) ||
 301             (nd && nd->mnt && MNT_IS_RDONLY(nd->mnt))) &&
 302             (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
 303                 return -EROFS;
 304         /* Nobody gets write access to an immutable file */
 305         if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
 306             return -EACCES;
 307         if (current->fsuid == inode->i_uid) {
 308                 mode >>= 6;
 309         } else if (test_opt(inode->i_sb, POSIX_ACL)) {
 310                 struct posix_acl *acl;
 311
 312                 /* The access ACL cannot grant access if the group class
 313                    permission bits don't contain all requested permissions. */
 314                 if (((mode >> 3) & mask & S_IRWXO) != mask)
 315                         goto check_groups;
 316                 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 317                 if (acl) {
 318                         int error = posix_acl_permission(inode, acl, mask);
 319                         posix_acl_release(acl);
 320                         if (error == -EACCES)
 321                                 goto check_capabilities;
 322                         return error;
 323                 } else
 324                         goto check_groups;
 325         } else {
 326 check_groups:
 327                 if (in_group_p(inode->i_gid))
 328                         mode >>= 3;
 329         }
 330         if ((mode & mask & S_IRWXO) == mask)
 331                 return 0;
 332
 333 check_capabilities:
 334         /* Allowed to override Discretionary Access Control? */
 335         if (!(mask & MAY_EXEC) ||
 336             (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
 337                 if (capable(CAP_DAC_OVERRIDE))
 338                         return 0;
 339         /* Read and search granted if capable(CAP_DAC_READ_SEARCH) */
 340         if (capable(CAP_DAC_READ_SEARCH) && ((mask == MAY_READ) ||
 341             (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))))
 342                 return 0;
 343         return -EACCES;
 344 }
 345
 346 /*
 347  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 348  *
 349  * dir->i_sem: down
 350  * inode->i_sem: up (access to inode is still exclusive)
 351  */
 352 int
 353 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 354 {
 355         struct posix_acl *acl = NULL;
 356         int error = 0;
 357
 358         if (!S_ISLNK(inode->i_mode)) {
 359                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 360                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 361                         if (IS_ERR(acl))
 362                                 return PTR_ERR(acl);
 363                 }
 364                 if (!acl)
 365                         inode->i_mode &= ~current->fs->umask;
 366         }
 367         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 368                 struct posix_acl *clone;
 369                 mode_t mode;
 370
 371                 if (S_ISDIR(inode->i_mode)) {
 372                         error = ext3_set_acl(handle, inode,
 373                                              ACL_TYPE_DEFAULT, acl);
 374                         if (error)
 375                                 goto cleanup;
 376                 }
 377                 clone = posix_acl_clone(acl, GFP_KERNEL);
 378                 error = -ENOMEM;
 379                 if (!clone)
 380                         goto cleanup;
 381
 382                 mode = inode->i_mode;
 383                 error = posix_acl_create_masq(clone, &mode);
 384                 if (error >= 0) {
 385                         inode->i_mode = mode;
 386                         if (error > 0) {
 387                                 /* This is an extended ACL */
 388                                 error = ext3_set_acl(handle, inode,
 389                                                      ACL_TYPE_ACCESS, clone);
 390                         }
 391                 }
 392                 posix_acl_release(clone);
 393         }
 394 cleanup:
 395         posix_acl_release(acl);
 396         return error;
 397 }
 398
 399 /*
 400  * Does chmod for an inode that may have an Access Control List. The
 401  * inode->i_mode field must be updated to the desired value by the caller
 402  * before calling this function.
 403  * Returns 0 on success, or a negative error number.
 404  *
 405  * We change the ACL rather than storing some ACL entries in the file
 406  * mode permission bits (which would be more efficient), because that
 407  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 408  * for directories) are added. There are no more bits available in the
 409  * file mode.
 410  *
 411  * inode->i_sem: down
 412  */
 413 int
 414 ext3_acl_chmod(struct inode *inode)
 415 {
 416         struct posix_acl *acl, *clone;
 417         int error;
 418
 419         if (S_ISLNK(inode->i_mode))
 420                 return -EOPNOTSUPP;
 421         if (!test_opt(inode->i_sb, POSIX_ACL))
 422                 return 0;
 423         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 424         if (IS_ERR(acl) || !acl)
 425                 return PTR_ERR(acl);
 426         clone = posix_acl_clone(acl, GFP_KERNEL);
 427         posix_acl_release(acl);
 428         if (!clone)
 429                 return -ENOMEM;
 430         error = posix_acl_chmod_masq(clone, inode->i_mode);
 431         if (!error) {
 432                 handle_t *handle;
 433                 int retries = 0;
 434
 435         retry:
 436                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 437                 if (IS_ERR(handle)) {
 438                         error = PTR_ERR(handle);
 439                         ext3_std_error(inode->i_sb, error);
 440                         goto out;
 441                 }
 442                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 443                 ext3_journal_stop(handle);
 444                 if (error == -ENOSPC &&
 445                     ext3_should_retry_alloc(inode->i_sb, &retries))
 446                         goto retry;
 447         }
 448 out:
 449         posix_acl_release(clone);
 450         return error;
 451 }
 452
 453 /*
 454  * Extended attribute handlers
 455  */
 456 static size_t
 457 ext3_xattr_list_acl_access(char *list, struct inode *inode,
 458                            const char *name, int name_len)
 459 {
 460         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 461
 462         if (!test_opt(inode->i_sb, POSIX_ACL))
 463                 return 0;
 464         if (list)
 465                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 466         return size;
 467 }
 468
 469 static size_t
 470 ext3_xattr_list_acl_default(char *list, struct inode *inode,
 471                             const char *name, int name_len)
 472 {
 473         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 474
 475         if (!test_opt(inode->i_sb, POSIX_ACL))
 476                 return 0;
 477         if (list)
 478                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 479         return size;
 480 }
 481
 482 static int
 483 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 484 {
 485         struct posix_acl *acl;
 486         int error;
 487
 488         if (!test_opt(inode->i_sb, POSIX_ACL))
 489                 return -EOPNOTSUPP;
 490
 491         acl = ext3_get_acl(inode, type);
 492         if (IS_ERR(acl))
 493                 return PTR_ERR(acl);
 494         if (acl == NULL)
 495                 return -ENODATA;
 496         error = posix_acl_to_xattr(acl, buffer, size);
 497         posix_acl_release(acl);
 498
 499         return error;
 500 }
 501
 502 static int
 503 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 504                           void *buffer, size_t size)
 505 {
 506         if (strcmp(name, "") != 0)
 507                 return -EINVAL;
 508         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 509 }
 510
 511 static int
 512 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 513                            void *buffer, size_t size)
 514 {
 515         if (strcmp(name, "") != 0)
 516                 return -EINVAL;
 517         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 518 }
 519
 520 static int
 521 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 522                    size_t size)
 523 {
 524         handle_t *handle;
 525         struct posix_acl *acl;
 526         int error, retries = 0;
 527
 528         if (!test_opt(inode->i_sb, POSIX_ACL))
 529                 return -EOPNOTSUPP;
 530         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 531                 return -EPERM;
 532
 533         if (value) {
 534                 acl = posix_acl_from_xattr(value, size);
 535                 if (IS_ERR(acl))
 536                         return PTR_ERR(acl);
 537                 else if (acl) {
 538                         error = posix_acl_valid(acl);
 539                         if (error)
 540                                 goto release_and_out;
 541                 }
 542         } else
 543                 acl = NULL;
 544
 545 retry:
 546         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 547         if (IS_ERR(handle))
 548                 return PTR_ERR(handle);
 549         error = ext3_set_acl(handle, inode, type, acl);
 550         ext3_journal_stop(handle);
 551         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 552                 goto retry;
 553
 554 release_and_out:
 555         posix_acl_release(acl);
 556         return error;
 557 }
 558
 559 static int
 560 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 561                           const void *value, size_t size, int flags)
 562 {
 563         if (strcmp(name, "") != 0)
 564                 return -EINVAL;
 565         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 566 }
 567
 568 static int
 569 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 570                            const void *value, size_t size, int flags)
 571 {
 572         if (strcmp(name, "") != 0)
 573                 return -EINVAL;
 574         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 575 }
 576
 577 struct ext3_xattr_handler ext3_xattr_acl_access_handler = {
 578         .prefix = XATTR_NAME_ACL_ACCESS,
 579         .list   = ext3_xattr_list_acl_access,
 580         .get    = ext3_xattr_get_acl_access,
 581         .set    = ext3_xattr_set_acl_access,
 582 };
 583
 584 struct ext3_xattr_handler ext3_xattr_acl_default_handler = {
 585         .prefix = XATTR_NAME_ACL_DEFAULT,
 586         .list   = ext3_xattr_list_acl_default,
 587         .get    = ext3_xattr_get_acl_default,
 588         .set    = ext3_xattr_set_acl_default,
 589 };
 590
 591 void
 592 exit_ext3_acl(void)
 593 {
 594         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 595                               &ext3_xattr_acl_access_handler);
 596         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 597                               &ext3_xattr_acl_default_handler);
 598 }
 599
 600 int __init
 601 init_ext3_acl(void)
 602 {
 603         int error;
 604
 605         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 606                                     &ext3_xattr_acl_access_handler);
 607         if (error)
 608                 goto fail;
 609         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 610                                     &ext3_xattr_acl_default_handler);
 611         if (error)
 612                 goto fail;
 613         return 0;
 614
 615 fail:
 616         exit_ext3_acl();
 617         return error;
 618 }