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 0;
 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
 432                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 433                 if (IS_ERR(handle)) {
 434                         error = PTR_ERR(handle);
 435                         ext3_std_error(inode->i_sb, error);
 436                         goto out;
 437                 }
 438                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 439                 ext3_journal_stop(handle);
 440         }
 441 out:
 442         posix_acl_release(clone);
 443         return error;
 444 }
 445
 446 /*
 447  * Extended attribute handlers
 448  */
 449 static size_t
 450 ext3_xattr_list_acl_access(char *list, struct inode *inode,
 451                            const char *name, int name_len)
 452 {
 453         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 454
 455         if (!test_opt(inode->i_sb, POSIX_ACL))
 456                 return 0;
 457         if (list)
 458                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 459         return size;
 460 }
 461
 462 static size_t
 463 ext3_xattr_list_acl_default(char *list, struct inode *inode,
 464                             const char *name, int name_len)
 465 {
 466         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 467
 468         if (!test_opt(inode->i_sb, POSIX_ACL))
 469                 return 0;
 470         if (list)
 471                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 472         return size;
 473 }
 474
 475 static int
 476 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 477 {
 478         struct posix_acl *acl;
 479         int error;
 480
 481         if (!test_opt(inode->i_sb, POSIX_ACL))
 482                 return -EOPNOTSUPP;
 483
 484         acl = ext3_get_acl(inode, type);
 485         if (IS_ERR(acl))
 486                 return PTR_ERR(acl);
 487         if (acl == NULL)
 488                 return -ENODATA;
 489         error = posix_acl_to_xattr(acl, buffer, size);
 490         posix_acl_release(acl);
 491
 492         return error;
 493 }
 494
 495 static int
 496 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 497                           void *buffer, size_t size)
 498 {
 499         if (strcmp(name, "") != 0)
 500                 return -EINVAL;
 501         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 502 }
 503
 504 static int
 505 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 506                            void *buffer, size_t size)
 507 {
 508         if (strcmp(name, "") != 0)
 509                 return -EINVAL;
 510         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 511 }
 512
 513 static int
 514 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 515                    size_t size)
 516 {
 517         handle_t *handle;
 518         struct posix_acl *acl;
 519         int error;
 520
 521         if (!test_opt(inode->i_sb, POSIX_ACL))
 522                 return -EOPNOTSUPP;
 523         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 524                 return -EPERM;
 525
 526         if (value) {
 527                 acl = posix_acl_from_xattr(value, size);
 528                 if (IS_ERR(acl))
 529                         return PTR_ERR(acl);
 530                 else if (acl) {
 531                         error = posix_acl_valid(acl);
 532                         if (error)
 533                                 goto release_and_out;
 534                 }
 535         } else
 536                 acl = NULL;
 537
 538         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 539         if (IS_ERR(handle))
 540                 return PTR_ERR(handle);
 541         error = ext3_set_acl(handle, inode, type, acl);
 542         ext3_journal_stop(handle);
 543
 544 release_and_out:
 545         posix_acl_release(acl);
 546         return error;
 547 }
 548
 549 static int
 550 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 551                           const void *value, size_t size, int flags)
 552 {
 553         if (strcmp(name, "") != 0)
 554                 return -EINVAL;
 555         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 556 }
 557
 558 static int
 559 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 560                            const void *value, size_t size, int flags)
 561 {
 562         if (strcmp(name, "") != 0)
 563                 return -EINVAL;
 564         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 565 }
 566
 567 struct ext3_xattr_handler ext3_xattr_acl_access_handler = {
 568         .prefix = XATTR_NAME_ACL_ACCESS,
 569         .list   = ext3_xattr_list_acl_access,
 570         .get    = ext3_xattr_get_acl_access,
 571         .set    = ext3_xattr_set_acl_access,
 572 };
 573
 574 struct ext3_xattr_handler ext3_xattr_acl_default_handler = {
 575         .prefix = XATTR_NAME_ACL_DEFAULT,
 576         .list   = ext3_xattr_list_acl_default,
 577         .get    = ext3_xattr_get_acl_default,
 578         .set    = ext3_xattr_set_acl_default,
 579 };
 580
 581 void
 582 exit_ext3_acl(void)
 583 {
 584         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 585                               &ext3_xattr_acl_access_handler);
 586         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 587                               &ext3_xattr_acl_default_handler);
 588 }
 589
 590 int __init
 591 init_ext3_acl(void)
 592 {
 593         int error;
 594
 595         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 596                                     &ext3_xattr_acl_access_handler);
 597         if (error)
 598                 goto fail;
 599         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 600                                     &ext3_xattr_acl_default_handler);
 601         if (error)
 602                 goto fail;
 603         return 0;
 604
 605 fail:
 606         exit_ext3_acl();
 607         return error;
 608 }