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 <linux/vs_base.h>
  15 #include "xattr.h"
  16 #include "acl.h"
  17
  18 /*
  19  * Convert from filesystem to in-memory representation.
  20  */
  21 static struct posix_acl *
  22 ext3_acl_from_disk(const void *value, size_t size)
  23 {
  24         const char *end = (char *)value + size;
  25         int n, count;
  26         struct posix_acl *acl;
  27
  28         if (!value)
  29                 return NULL;
  30         if (size < sizeof(ext3_acl_header))
  31                  return ERR_PTR(-EINVAL);
  32         if (((ext3_acl_header *)value)->a_version !=
  33             cpu_to_le32(EXT3_ACL_VERSION))
  34                 return ERR_PTR(-EINVAL);
  35         value = (char *)value + sizeof(ext3_acl_header);
  36         count = ext3_acl_count(size);
  37         if (count < 0)
  38                 return ERR_PTR(-EINVAL);
  39         if (count == 0)
  40                 return NULL;
  41         acl = posix_acl_alloc(count, GFP_KERNEL);
  42         if (!acl)
  43                 return ERR_PTR(-ENOMEM);
  44         for (n=0; n < count; n++) {
  45                 ext3_acl_entry *entry =
  46                         (ext3_acl_entry *)value;
  47                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  48                         goto fail;
  49                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  50                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  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(ext3_acl_entry_short);
  58                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  59                                 break;
  60
  61                         case ACL_USER:
  62                         case ACL_GROUP:
  63                                 value = (char *)value + sizeof(ext3_acl_entry);
  64                                 if ((char *)value > end)
  65                                         goto fail;
  66                                 acl->a_entries[n].e_id =
  67                                         le32_to_cpu(entry->e_id);
  68                                 break;
  69
  70                         default:
  71                                 goto fail;
  72                 }
  73         }
  74         if (value != end)
  75                 goto fail;
  76         return acl;
  77
  78 fail:
  79         posix_acl_release(acl);
  80         return ERR_PTR(-EINVAL);
  81 }
  82
  83 /*
  84  * Convert from in-memory to filesystem representation.
  85  */
  86 static void *
  87 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  88 {
  89         ext3_acl_header *ext_acl;
  90         char *e;
  91         size_t n;
  92
  93         *size = ext3_acl_size(acl->a_count);
  94         ext_acl = (ext3_acl_header *)kmalloc(sizeof(ext3_acl_header) +
  95                 acl->a_count * sizeof(ext3_acl_entry), GFP_KERNEL);
  96         if (!ext_acl)
  97                 return ERR_PTR(-ENOMEM);
  98         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  99         e = (char *)ext_acl + sizeof(ext3_acl_header);
 100         for (n=0; n < acl->a_count; n++) {
 101                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
 102                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 103                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 104                 switch(acl->a_entries[n].e_tag) {
 105                         case ACL_USER:
 106                         case ACL_GROUP:
 107                                 entry->e_id =
 108                                         cpu_to_le32(acl->a_entries[n].e_id);
 109                                 e += sizeof(ext3_acl_entry);
 110                                 break;
 111
 112                         case ACL_USER_OBJ:
 113                         case ACL_GROUP_OBJ:
 114                         case ACL_MASK:
 115                         case ACL_OTHER:
 116                                 e += sizeof(ext3_acl_entry_short);
 117                                 break;
 118
 119                         default:
 120                                 goto fail;
 121                 }
 122         }
 123         return (char *)ext_acl;
 124
 125 fail:
 126         kfree(ext_acl);
 127         return ERR_PTR(-EINVAL);
 128 }
 129
 130 static inline struct posix_acl *
 131 ext3_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 132 {
 133         struct posix_acl *acl = EXT3_ACL_NOT_CACHED;
 134
 135         spin_lock(&inode->i_lock);
 136         if (*i_acl != EXT3_ACL_NOT_CACHED)
 137                 acl = posix_acl_dup(*i_acl);
 138         spin_unlock(&inode->i_lock);
 139
 140         return acl;
 141 }
 142
 143 static inline void
 144 ext3_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 145                   struct posix_acl *acl)
 146 {
 147         spin_lock(&inode->i_lock);
 148         if (*i_acl != EXT3_ACL_NOT_CACHED)
 149                 posix_acl_release(*i_acl);
 150         *i_acl = posix_acl_dup(acl);
 151         spin_unlock(&inode->i_lock);
 152 }
 153
 154 /*
 155  * Inode operation get_posix_acl().
 156  *
 157  * inode->i_sem: don't care
 158  */
 159 static struct posix_acl *
 160 ext3_get_acl(struct inode *inode, int type)
 161 {
 162         struct ext3_inode_info *ei = EXT3_I(inode);
 163         int name_index;
 164         char *value = NULL;
 165         struct posix_acl *acl;
 166         int retval;
 167
 168         if (!test_opt(inode->i_sb, POSIX_ACL))
 169                 return NULL;
 170
 171         switch(type) {
 172                 case ACL_TYPE_ACCESS:
 173                         acl = ext3_iget_acl(inode, &ei->i_acl);
 174                         if (acl != EXT3_ACL_NOT_CACHED)
 175                                 return acl;
 176                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 177                         break;
 178
 179                 case ACL_TYPE_DEFAULT:
 180                         acl = ext3_iget_acl(inode, &ei->i_default_acl);
 181                         if (acl != EXT3_ACL_NOT_CACHED)
 182                                 return acl;
 183                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 184                         break;
 185
 186                 default:
 187                         return ERR_PTR(-EINVAL);
 188         }
 189         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 190         if (retval > 0) {
 191                 value = kmalloc(retval, GFP_KERNEL);
 192                 if (!value)
 193                         return ERR_PTR(-ENOMEM);
 194                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 195         }
 196         if (retval > 0)
 197                 acl = ext3_acl_from_disk(value, retval);
 198         else if (retval == -ENODATA || retval == -ENOSYS)
 199                 acl = NULL;
 200         else
 201                 acl = ERR_PTR(retval);
 202         if (value)
 203                 kfree(value);
 204
 205         if (!IS_ERR(acl)) {
 206                 switch(type) {
 207                         case ACL_TYPE_ACCESS:
 208                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 209                                 break;
 210
 211                         case ACL_TYPE_DEFAULT:
 212                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 213                                 break;
 214                 }
 215         }
 216         return acl;
 217 }
 218
 219 /*
 220  * Set the access or default ACL of an inode.
 221  *
 222  * inode->i_sem: down unless called from ext3_new_inode
 223  */
 224 static int
 225 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 226              struct posix_acl *acl)
 227 {
 228         struct ext3_inode_info *ei = EXT3_I(inode);
 229         int name_index;
 230         void *value = NULL;
 231         size_t size;
 232         int error;
 233
 234         if (S_ISLNK(inode->i_mode))
 235                 return -EOPNOTSUPP;
 236
 237         switch(type) {
 238                 case ACL_TYPE_ACCESS:
 239                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 240                         if (acl) {
 241                                 mode_t mode = inode->i_mode;
 242                                 error = posix_acl_equiv_mode(acl, &mode);
 243                                 if (error < 0)
 244                                         return error;
 245                                 else {
 246                                         inode->i_mode = mode;
 247                                         ext3_mark_inode_dirty(handle, inode);
 248                                         if (error == 0)
 249                                                 acl = NULL;
 250                                 }
 251                         }
 252                         break;
 253
 254                 case ACL_TYPE_DEFAULT:
 255                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 256                         if (!S_ISDIR(inode->i_mode))
 257                                 return acl ? -EACCES : 0;
 258                         break;
 259
 260                 default:
 261                         return -EINVAL;
 262         }
 263         if (acl) {
 264                 if (acl->a_count > EXT3_ACL_MAX_ENTRIES)
 265                         return -EINVAL;
 266                 value = ext3_acl_to_disk(acl, &size);
 267                 if (IS_ERR(value))
 268                         return (int)PTR_ERR(value);
 269         }
 270
 271         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 272                                       value, size, 0);
 273
 274         if (value)
 275                 kfree(value);
 276         if (!error) {
 277                 switch(type) {
 278                         case ACL_TYPE_ACCESS:
 279                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 280                                 break;
 281
 282                         case ACL_TYPE_DEFAULT:
 283                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 284                                 break;
 285                 }
 286         }
 287         return error;
 288 }
 289
 290 /*
 291  * Inode operation permission().
 292  *
 293  * inode->i_sem: don't care
 294  */
 295 int
 296 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 297 {
 298         int mode = inode->i_mode;
 299
 300         /* Prevent vservers from escaping chroot() barriers */
 301         if (IS_BARRIER(inode) && !vx_check(0, VX_ADMIN))
 302                 return -EACCES;
 303         /* Nobody gets write access to a read-only fs */
 304         if ((mask & MAY_WRITE) && (IS_RDONLY(inode) ||
 305             (nd && nd->mnt && MNT_IS_RDONLY(nd->mnt))) &&
 306             (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
 307                 return -EROFS;
 308         /* Nobody gets write access to an immutable file */
 309         if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
 310             return -EACCES;
 311         if (current->fsuid == inode->i_uid) {
 312                 mode >>= 6;
 313         } else if (test_opt(inode->i_sb, POSIX_ACL)) {
 314                 struct posix_acl *acl;
 315
 316                 /* The access ACL cannot grant access if the group class
 317                    permission bits don't contain all requested permissions. */
 318                 if (((mode >> 3) & mask & S_IRWXO) != mask)
 319                         goto check_groups;
 320                 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 321                 if (acl) {
 322                         int error = posix_acl_permission(inode, acl, mask);
 323                         posix_acl_release(acl);
 324                         if (error == -EACCES)
 325                                 goto check_capabilities;
 326                         return error;
 327                 } else
 328                         goto check_groups;
 329         } else {
 330 check_groups:
 331                 if (in_group_p(inode->i_gid))
 332                         mode >>= 3;
 333         }
 334         if ((mode & mask & S_IRWXO) == mask)
 335                 return 0;
 336
 337 check_capabilities:
 338         /* Allowed to override Discretionary Access Control? */
 339         if (!(mask & MAY_EXEC) ||
 340             (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
 341                 if (capable(CAP_DAC_OVERRIDE))
 342                         return 0;
 343         /* Read and search granted if capable(CAP_DAC_READ_SEARCH) */
 344         if (capable(CAP_DAC_READ_SEARCH) && ((mask == MAY_READ) ||
 345             (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))))
 346                 return 0;
 347         return -EACCES;
 348 }
 349
 350 /*
 351  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 352  *
 353  * dir->i_sem: down
 354  * inode->i_sem: up (access to inode is still exclusive)
 355  */
 356 int
 357 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 358 {
 359         struct posix_acl *acl = NULL;
 360         int error = 0;
 361
 362         if (!S_ISLNK(inode->i_mode)) {
 363                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 364                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 365                         if (IS_ERR(acl))
 366                                 return PTR_ERR(acl);
 367                 }
 368                 if (!acl)
 369                         inode->i_mode &= ~current->fs->umask;
 370         }
 371         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 372                 struct posix_acl *clone;
 373                 mode_t mode;
 374
 375                 if (S_ISDIR(inode->i_mode)) {
 376                         error = ext3_set_acl(handle, inode,
 377                                              ACL_TYPE_DEFAULT, acl);
 378                         if (error)
 379                                 goto cleanup;
 380                 }
 381                 clone = posix_acl_clone(acl, GFP_KERNEL);
 382                 error = -ENOMEM;
 383                 if (!clone)
 384                         goto cleanup;
 385
 386                 mode = inode->i_mode;
 387                 error = posix_acl_create_masq(clone, &mode);
 388                 if (error >= 0) {
 389                         inode->i_mode = mode;
 390                         if (error > 0) {
 391                                 /* This is an extended ACL */
 392                                 error = ext3_set_acl(handle, inode,
 393                                                      ACL_TYPE_ACCESS, clone);
 394                         }
 395                 }
 396                 posix_acl_release(clone);
 397         }
 398 cleanup:
 399         posix_acl_release(acl);
 400         return error;
 401 }
 402
 403 /*
 404  * Does chmod for an inode that may have an Access Control List. The
 405  * inode->i_mode field must be updated to the desired value by the caller
 406  * before calling this function.
 407  * Returns 0 on success, or a negative error number.
 408  *
 409  * We change the ACL rather than storing some ACL entries in the file
 410  * mode permission bits (which would be more efficient), because that
 411  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 412  * for directories) are added. There are no more bits available in the
 413  * file mode.
 414  *
 415  * inode->i_sem: down
 416  */
 417 int
 418 ext3_acl_chmod(struct inode *inode)
 419 {
 420         struct posix_acl *acl, *clone;
 421         int error;
 422
 423         if (S_ISLNK(inode->i_mode))
 424                 return -EOPNOTSUPP;
 425         if (!test_opt(inode->i_sb, POSIX_ACL))
 426                 return 0;
 427         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 428         if (IS_ERR(acl) || !acl)
 429                 return PTR_ERR(acl);
 430         clone = posix_acl_clone(acl, GFP_KERNEL);
 431         posix_acl_release(acl);
 432         if (!clone)
 433                 return -ENOMEM;
 434         error = posix_acl_chmod_masq(clone, inode->i_mode);
 435         if (!error) {
 436                 handle_t *handle;
 437                 int retries = 0;
 438
 439         retry:
 440                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 441                 if (IS_ERR(handle)) {
 442                         error = PTR_ERR(handle);
 443                         ext3_std_error(inode->i_sb, error);
 444                         goto out;
 445                 }
 446                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 447                 ext3_journal_stop(handle);
 448                 if (error == -ENOSPC &&
 449                     ext3_should_retry_alloc(inode->i_sb, &retries))
 450                         goto retry;
 451         }
 452 out:
 453         posix_acl_release(clone);
 454         return error;
 455 }
 456
 457 /*
 458  * Extended attribute handlers
 459  */
 460 static size_t
 461 ext3_xattr_list_acl_access(char *list, struct inode *inode,
 462                            const char *name, int name_len)
 463 {
 464         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 465
 466         if (!test_opt(inode->i_sb, POSIX_ACL))
 467                 return 0;
 468         if (list)
 469                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 470         return size;
 471 }
 472
 473 static size_t
 474 ext3_xattr_list_acl_default(char *list, struct inode *inode,
 475                             const char *name, int name_len)
 476 {
 477         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 478
 479         if (!test_opt(inode->i_sb, POSIX_ACL))
 480                 return 0;
 481         if (list)
 482                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 483         return size;
 484 }
 485
 486 static int
 487 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 488 {
 489         struct posix_acl *acl;
 490         int error;
 491
 492         if (!test_opt(inode->i_sb, POSIX_ACL))
 493                 return -EOPNOTSUPP;
 494
 495         acl = ext3_get_acl(inode, type);
 496         if (IS_ERR(acl))
 497                 return PTR_ERR(acl);
 498         if (acl == NULL)
 499                 return -ENODATA;
 500         error = posix_acl_to_xattr(acl, buffer, size);
 501         posix_acl_release(acl);
 502
 503         return error;
 504 }
 505
 506 static int
 507 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 508                           void *buffer, size_t size)
 509 {
 510         if (strcmp(name, "") != 0)
 511                 return -EINVAL;
 512         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 513 }
 514
 515 static int
 516 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 517                            void *buffer, size_t size)
 518 {
 519         if (strcmp(name, "") != 0)
 520                 return -EINVAL;
 521         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 522 }
 523
 524 static int
 525 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 526                    size_t size)
 527 {
 528         handle_t *handle;
 529         struct posix_acl *acl;
 530         int error, retries = 0;
 531
 532         if (!test_opt(inode->i_sb, POSIX_ACL))
 533                 return -EOPNOTSUPP;
 534         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 535                 return -EPERM;
 536
 537         if (value) {
 538                 acl = posix_acl_from_xattr(value, size);
 539                 if (IS_ERR(acl))
 540                         return PTR_ERR(acl);
 541                 else if (acl) {
 542                         error = posix_acl_valid(acl);
 543                         if (error)
 544                                 goto release_and_out;
 545                 }
 546         } else
 547                 acl = NULL;
 548
 549 retry:
 550         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 551         if (IS_ERR(handle))
 552                 return PTR_ERR(handle);
 553         error = ext3_set_acl(handle, inode, type, acl);
 554         ext3_journal_stop(handle);
 555         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 556                 goto retry;
 557
 558 release_and_out:
 559         posix_acl_release(acl);
 560         return error;
 561 }
 562
 563 static int
 564 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 565                           const void *value, size_t size, int flags)
 566 {
 567         if (strcmp(name, "") != 0)
 568                 return -EINVAL;
 569         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 570 }
 571
 572 static int
 573 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 574                            const void *value, size_t size, int flags)
 575 {
 576         if (strcmp(name, "") != 0)
 577                 return -EINVAL;
 578         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 579 }
 580
 581 struct ext3_xattr_handler ext3_xattr_acl_access_handler = {
 582         .prefix = XATTR_NAME_ACL_ACCESS,
 583         .list   = ext3_xattr_list_acl_access,
 584         .get    = ext3_xattr_get_acl_access,
 585         .set    = ext3_xattr_set_acl_access,
 586 };
 587
 588 struct ext3_xattr_handler ext3_xattr_acl_default_handler = {
 589         .prefix = XATTR_NAME_ACL_DEFAULT,
 590         .list   = ext3_xattr_list_acl_default,
 591         .get    = ext3_xattr_get_acl_default,
 592         .set    = ext3_xattr_set_acl_default,
 593 };
 594
 595 void
 596 exit_ext3_acl(void)
 597 {
 598         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 599                               &ext3_xattr_acl_access_handler);
 600         ext3_xattr_unregister(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 601                               &ext3_xattr_acl_default_handler);
 602 }
 603
 604 int __init
 605 init_ext3_acl(void)
 606 {
 607         int error;
 608
 609         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_ACCESS,
 610                                     &ext3_xattr_acl_access_handler);
 611         if (error)
 612                 goto fail;
 613         error = ext3_xattr_register(EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT,
 614                                     &ext3_xattr_acl_default_handler);
 615         if (error)
 616                 goto fail;
 617         return 0;
 618
 619 fail:
 620         exit_ext3_acl();
 621         return error;
 622 }