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/ext3_jbd.h>
  12 #include <linux/ext3_fs.h>
  13 #include "xattr.h"
  14 #include "acl.h"
  15
  16 /*
  17  * Convert from filesystem to in-memory representation.
  18  */
  19 static struct posix_acl *
  20 ext3_acl_from_disk(const void *value, size_t size)
  21 {
  22         const char *end = (char *)value + size;
  23         int n, count;
  24         struct posix_acl *acl;
  25
  26         if (!value)
  27                 return NULL;
  28         if (size < sizeof(ext3_acl_header))
  29                  return ERR_PTR(-EINVAL);
  30         if (((ext3_acl_header *)value)->a_version !=
  31             cpu_to_le32(EXT3_ACL_VERSION))
  32                 return ERR_PTR(-EINVAL);
  33         value = (char *)value + sizeof(ext3_acl_header);
  34         count = ext3_acl_count(size);
  35         if (count < 0)
  36                 return ERR_PTR(-EINVAL);
  37         if (count == 0)
  38                 return NULL;
  39         acl = posix_acl_alloc(count, GFP_KERNEL);
  40         if (!acl)
  41                 return ERR_PTR(-ENOMEM);
  42         for (n=0; n < count; n++) {
  43                 ext3_acl_entry *entry =
  44                         (ext3_acl_entry *)value;
  45                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  46                         goto fail;
  47                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  48                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  49                 switch(acl->a_entries[n].e_tag) {
  50                         case ACL_USER_OBJ:
  51                         case ACL_GROUP_OBJ:
  52                         case ACL_MASK:
  53                         case ACL_OTHER:
  54                                 value = (char *)value +
  55                                         sizeof(ext3_acl_entry_short);
  56                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  57                                 break;
  58
  59                         case ACL_USER:
  60                         case ACL_GROUP:
  61                                 value = (char *)value + sizeof(ext3_acl_entry);
  62                                 if ((char *)value > end)
  63                                         goto fail;
  64                                 acl->a_entries[n].e_id =
  65                                         le32_to_cpu(entry->e_id);
  66                                 break;
  67
  68                         default:
  69                                 goto fail;
  70                 }
  71         }
  72         if (value != end)
  73                 goto fail;
  74         return acl;
  75
  76 fail:
  77         posix_acl_release(acl);
  78         return ERR_PTR(-EINVAL);
  79 }
  80
  81 /*
  82  * Convert from in-memory to filesystem representation.
  83  */
  84 static void *
  85 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  86 {
  87         ext3_acl_header *ext_acl;
  88         char *e;
  89         size_t n;
  90
  91         *size = ext3_acl_size(acl->a_count);
  92         ext_acl = (ext3_acl_header *)kmalloc(sizeof(ext3_acl_header) +
  93                 acl->a_count * sizeof(ext3_acl_entry), GFP_KERNEL);
  94         if (!ext_acl)
  95                 return ERR_PTR(-ENOMEM);
  96         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  97         e = (char *)ext_acl + sizeof(ext3_acl_header);
  98         for (n=0; n < acl->a_count; n++) {
  99                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
 100                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 101                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 102                 switch(acl->a_entries[n].e_tag) {
 103                         case ACL_USER:
 104                         case ACL_GROUP:
 105                                 entry->e_id =
 106                                         cpu_to_le32(acl->a_entries[n].e_id);
 107                                 e += sizeof(ext3_acl_entry);
 108                                 break;
 109
 110                         case ACL_USER_OBJ:
 111                         case ACL_GROUP_OBJ:
 112                         case ACL_MASK:
 113                         case ACL_OTHER:
 114                                 e += sizeof(ext3_acl_entry_short);
 115                                 break;
 116
 117                         default:
 118                                 goto fail;
 119                 }
 120         }
 121         return (char *)ext_acl;
 122
 123 fail:
 124         kfree(ext_acl);
 125         return ERR_PTR(-EINVAL);
 126 }
 127
 128 static inline struct posix_acl *
 129 ext3_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 130 {
 131         struct posix_acl *acl = EXT3_ACL_NOT_CACHED;
 132
 133         spin_lock(&inode->i_lock);
 134         if (*i_acl != EXT3_ACL_NOT_CACHED)
 135                 acl = posix_acl_dup(*i_acl);
 136         spin_unlock(&inode->i_lock);
 137
 138         return acl;
 139 }
 140
 141 static inline void
 142 ext3_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 143                   struct posix_acl *acl)
 144 {
 145         spin_lock(&inode->i_lock);
 146         if (*i_acl != EXT3_ACL_NOT_CACHED)
 147                 posix_acl_release(*i_acl);
 148         *i_acl = posix_acl_dup(acl);
 149         spin_unlock(&inode->i_lock);
 150 }
 151
 152 /*
 153  * Inode operation get_posix_acl().
 154  *
 155  * inode->i_sem: don't care
 156  */
 157 static struct posix_acl *
 158 ext3_get_acl(struct inode *inode, int type)
 159 {
 160         struct ext3_inode_info *ei = EXT3_I(inode);
 161         int name_index;
 162         char *value = NULL;
 163         struct posix_acl *acl;
 164         int retval;
 165
 166         if (!test_opt(inode->i_sb, POSIX_ACL))
 167                 return NULL;
 168
 169         switch(type) {
 170                 case ACL_TYPE_ACCESS:
 171                         acl = ext3_iget_acl(inode, &ei->i_acl);
 172                         if (acl != EXT3_ACL_NOT_CACHED)
 173                                 return acl;
 174                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 175                         break;
 176
 177                 case ACL_TYPE_DEFAULT:
 178                         acl = ext3_iget_acl(inode, &ei->i_default_acl);
 179                         if (acl != EXT3_ACL_NOT_CACHED)
 180                                 return acl;
 181                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 182                         break;
 183
 184                 default:
 185                         return ERR_PTR(-EINVAL);
 186         }
 187         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 188         if (retval > 0) {
 189                 value = kmalloc(retval, GFP_KERNEL);
 190                 if (!value)
 191                         return ERR_PTR(-ENOMEM);
 192                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 193         }
 194         if (retval > 0)
 195                 acl = ext3_acl_from_disk(value, retval);
 196         else if (retval == -ENODATA || retval == -ENOSYS)
 197                 acl = NULL;
 198         else
 199                 acl = ERR_PTR(retval);
 200         if (value)
 201                 kfree(value);
 202
 203         if (!IS_ERR(acl)) {
 204                 switch(type) {
 205                         case ACL_TYPE_ACCESS:
 206                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 207                                 break;
 208
 209                         case ACL_TYPE_DEFAULT:
 210                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 211                                 break;
 212                 }
 213         }
 214         return acl;
 215 }
 216
 217 /*
 218  * Set the access or default ACL of an inode.
 219  *
 220  * inode->i_sem: down unless called from ext3_new_inode
 221  */
 222 static int
 223 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 224              struct posix_acl *acl)
 225 {
 226         struct ext3_inode_info *ei = EXT3_I(inode);
 227         int name_index;
 228         void *value = NULL;
 229         size_t size;
 230         int error;
 231
 232         if (S_ISLNK(inode->i_mode))
 233                 return -EOPNOTSUPP;
 234
 235         switch(type) {
 236                 case ACL_TYPE_ACCESS:
 237                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 238                         if (acl) {
 239                                 mode_t mode = inode->i_mode;
 240                                 error = posix_acl_equiv_mode(acl, &mode);
 241                                 if (error < 0)
 242                                         return error;
 243                                 else {
 244                                         inode->i_mode = mode;
 245                                         ext3_mark_inode_dirty(handle, inode);
 246                                         if (error == 0)
 247                                                 acl = NULL;
 248                                 }
 249                         }
 250                         break;
 251
 252                 case ACL_TYPE_DEFAULT:
 253                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 254                         if (!S_ISDIR(inode->i_mode))
 255                                 return acl ? -EACCES : 0;
 256                         break;
 257
 258                 default:
 259                         return -EINVAL;
 260         }
 261         if (acl) {
 262                 if (acl->a_count > EXT3_ACL_MAX_ENTRIES)
 263                         return -EINVAL;
 264                 value = ext3_acl_to_disk(acl, &size);
 265                 if (IS_ERR(value))
 266                         return (int)PTR_ERR(value);
 267         }
 268
 269         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 270                                       value, size, 0);
 271
 272         if (value)
 273                 kfree(value);
 274         if (!error) {
 275                 switch(type) {
 276                         case ACL_TYPE_ACCESS:
 277                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 278                                 break;
 279
 280                         case ACL_TYPE_DEFAULT:
 281                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 282                                 break;
 283                 }
 284         }
 285         return error;
 286 }
 287
 288 /*
 289  * Inode operation permission().
 290  *
 291  * inode->i_sem: don't care
 292  */
 293 int
 294 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 295 {
 296         int mode = inode->i_mode;
 297
 298         /* Nobody gets write access to a read-only fs */
 299         if ((mask & MAY_WRITE) && IS_RDONLY(inode) &&
 300             (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
 301                 return -EROFS;
 302         /* Nobody gets write access to an immutable file */
 303         if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
 304             return -EACCES;
 305         if (current->fsuid == inode->i_uid) {
 306                 mode >>= 6;
 307         } else if (test_opt(inode->i_sb, POSIX_ACL)) {
 308                 struct posix_acl *acl;
 309
 310                 /* The access ACL cannot grant access if the group class
 311                    permission bits don't contain all requested permissions. */
 312                 if (((mode >> 3) & mask & S_IRWXO) != mask)
 313                         goto check_groups;
 314                 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 315                 if (acl) {
 316                         int error = posix_acl_permission(inode, acl, mask);
 317                         posix_acl_release(acl);
 318                         if (error == -EACCES)
 319                                 goto check_capabilities;
 320                         return error;
 321                 } else
 322                         goto check_groups;
 323         } else {
 324 check_groups:
 325                 if (in_group_p(inode->i_gid))
 326                         mode >>= 3;
 327         }
 328         if ((mode & mask & S_IRWXO) == mask)
 329                 return 0;
 330
 331 check_capabilities:
 332         /* Allowed to override Discretionary Access Control? */
 333         if (!(mask & MAY_EXEC) ||
 334             (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
 335                 if (capable(CAP_DAC_OVERRIDE))
 336                         return 0;
 337         /* Read and search granted if capable(CAP_DAC_READ_SEARCH) */
 338         if (capable(CAP_DAC_READ_SEARCH) && ((mask == MAY_READ) ||
 339             (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))))
 340                 return 0;
 341         return -EACCES;
 342 }
 343
 344 /*
 345  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 346  *
 347  * dir->i_sem: down
 348  * inode->i_sem: up (access to inode is still exclusive)
 349  */
 350 int
 351 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 352 {
 353         struct posix_acl *acl = NULL;
 354         int error = 0;
 355
 356         if (!S_ISLNK(inode->i_mode)) {
 357                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 358                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 359                         if (IS_ERR(acl))
 360                                 return PTR_ERR(acl);
 361                 }
 362                 if (!acl)
 363                         inode->i_mode &= ~current->fs->umask;
 364         }
 365         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 366                 struct posix_acl *clone;
 367                 mode_t mode;
 368
 369                 if (S_ISDIR(inode->i_mode)) {
 370                         error = ext3_set_acl(handle, inode,
 371                                              ACL_TYPE_DEFAULT, acl);
 372                         if (error)
 373                                 goto cleanup;
 374                 }
 375                 clone = posix_acl_clone(acl, GFP_KERNEL);
 376                 error = -ENOMEM;
 377                 if (!clone)
 378                         goto cleanup;
 379
 380                 mode = inode->i_mode;
 381                 error = posix_acl_create_masq(clone, &mode);
 382                 if (error >= 0) {
 383                         inode->i_mode = mode;
 384                         if (error > 0) {
 385                                 /* This is an extended ACL */
 386                                 error = ext3_set_acl(handle, inode,
 387                                                      ACL_TYPE_ACCESS, clone);
 388                         }
 389                 }
 390                 posix_acl_release(clone);
 391         }
 392 cleanup:
 393         posix_acl_release(acl);
 394         return error;
 395 }
 396
 397 /*
 398  * Does chmod for an inode that may have an Access Control List. The
 399  * inode->i_mode field must be updated to the desired value by the caller
 400  * before calling this function.
 401  * Returns 0 on success, or a negative error number.
 402  *
 403  * We change the ACL rather than storing some ACL entries in the file
 404  * mode permission bits (which would be more efficient), because that
 405  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 406  * for directories) are added. There are no more bits available in the
 407  * file mode.
 408  *
 409  * inode->i_sem: down
 410  */
 411 int
 412 ext3_acl_chmod(struct inode *inode)
 413 {
 414         struct posix_acl *acl, *clone;
 415         int error;
 416
 417         if (S_ISLNK(inode->i_mode))
 418                 return -EOPNOTSUPP;
 419         if (!test_opt(inode->i_sb, POSIX_ACL))
 420                 return 0;
 421         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 422         if (IS_ERR(acl) || !acl)
 423                 return PTR_ERR(acl);
 424         clone = posix_acl_clone(acl, GFP_KERNEL);
 425         posix_acl_release(acl);
 426         if (!clone)
 427                 return -ENOMEM;
 428         error = posix_acl_chmod_masq(clone, inode->i_mode);
 429         if (!error) {
 430                 handle_t *handle;
 431                 int retries = 0;
 432
 433         retry:
 434                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 435                 if (IS_ERR(handle)) {
 436                         error = PTR_ERR(handle);
 437                         ext3_std_error(inode->i_sb, error);
 438                         goto out;
 439                 }
 440                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 441                 ext3_journal_stop(handle);
 442                 if (error == -ENOSPC &&
 443                     ext3_should_retry_alloc(inode->i_sb, &retries))
 444                         goto retry;
 445         }
 446 out:
 447         posix_acl_release(clone);
 448         return error;
 449 }
 450
 451 /*
 452  * Extended attribute handlers
 453  */
 454 static size_t
 455 ext3_xattr_list_acl_access(char *list, struct inode *inode,
 456                            const char *name, int name_len)
 457 {
 458         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 459
 460         if (!test_opt(inode->i_sb, POSIX_ACL))
 461                 return 0;
 462         if (list)
 463                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 464         return size;
 465 }
 466
 467 static size_t
 468 ext3_xattr_list_acl_default(char *list, struct inode *inode,
 469                             const char *name, int name_len)
 470 {
 471         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 472
 473         if (!test_opt(inode->i_sb, POSIX_ACL))
 474                 return 0;
 475         if (list)
 476                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 477         return size;
 478 }
 479
 480 static int
 481 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 482 {
 483         struct posix_acl *acl;
 484         int error;
 485
 486         if (!test_opt(inode->i_sb, POSIX_ACL))
 487                 return -EOPNOTSUPP;
 488
 489         acl = ext3_get_acl(inode, type);
 490         if (IS_ERR(acl))
 491                 return PTR_ERR(acl);
 492         if (acl == NULL)
 493                 return -ENODATA;
 494         error = posix_acl_to_xattr(acl, buffer, size);
 495         posix_acl_release(acl);
 496
 497         return error;
 498 }
 499
 500 static int
 501 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 502                           void *buffer, size_t size)
 503 {
 504         if (strcmp(name, "") != 0)
 505                 return -EINVAL;
 506         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 507 }
 508
 509 static int
 510 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 511                            void *buffer, size_t size)
 512 {
 513         if (strcmp(name, "") != 0)
 514                 return -EINVAL;
 515         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 516 }
 517
 518 static int
 519 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 520                    size_t size)
 521 {
 522         handle_t *handle;
 523         struct posix_acl *acl;
 524         int error, retries = 0;
 525
 526         if (!test_opt(inode->i_sb, POSIX_ACL))
 527                 return -EOPNOTSUPP;
 528         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 529                 return -EPERM;
 530
 531         if (value) {
 532                 acl = posix_acl_from_xattr(value, size);
 533                 if (IS_ERR(acl))
 534                         return PTR_ERR(acl);
 535                 else if (acl) {
 536                         error = posix_acl_valid(acl);
 537                         if (error)
 538                                 goto release_and_out;
 539                 }
 540         } else
 541                 acl = NULL;
 542
 543 retry:
 544         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 545         if (IS_ERR(handle))
 546                 return PTR_ERR(handle);
 547         error = ext3_set_acl(handle, inode, type, acl);
 548         ext3_journal_stop(handle);
 549         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 550                 goto retry;
 551
 552 release_and_out:
 553         posix_acl_release(acl);
 554         return error;
 555 }
 556
 557 static int
 558 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 559                           const void *value, size_t size, int flags)
 560 {
 561         if (strcmp(name, "") != 0)
 562                 return -EINVAL;
 563         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 564 }
 565
 566 static int
 567 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 568                            const void *value, size_t size, int flags)
 569 {
 570         if (strcmp(name, "") != 0)
 571                 return -EINVAL;
 572         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 573 }
 574
 575 struct ext3_xattr_handler ext3_xattr_acl_access_handler = {
 576         .prefix = XATTR_NAME_ACL_ACCESS,
 577         .list   = ext3_xattr_list_acl_access,
 578         .get    = ext3_xattr_get_acl_access,
 579         .set    = ext3_xattr_set_acl_access,
 580 };
 581
 582 struct ext3_xattr_handler ext3_xattr_acl_default_handler = {
 583         .prefix = XATTR_NAME_ACL_DEFAULT,
 584         .list   = ext3_xattr_list_acl_default,
 585         .get    = ext3_xattr_get_acl_default,
 586         .set    = ext3_xattr_set_acl_default,
 587 };
 588
 589 void
 590 exit_ext3_acl(void)
 591 {
 592         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 593                               &ext3_xattr_acl_access_handler);
 594         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 595                               &ext3_xattr_acl_default_handler);
 596 }
 597
 598 int __init
 599 init_ext3_acl(void)
 600 {
 601         int error;
 602
 603         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 604                                     &ext3_xattr_acl_access_handler);
 605         if (error)
 606                 goto fail;
 607         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 608                                     &ext3_xattr_acl_default_handler);
 609         if (error)
 610                 goto fail;
 611         return 0;
 612
 613 fail:
 614         exit_ext3_acl();
 615         return error;
 616 }