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         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                 value = ext3_acl_to_disk(acl, &size);
 264                 if (IS_ERR(value))
 265                         return (int)PTR_ERR(value);
 266         }
 267
 268         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 269                                       value, size, 0);
 270
 271         kfree(value);
 272         if (!error) {
 273                 switch(type) {
 274                         case ACL_TYPE_ACCESS:
 275                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 276                                 break;
 277
 278                         case ACL_TYPE_DEFAULT:
 279                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 280                                 break;
 281                 }
 282         }
 283         return error;
 284 }
 285
 286 static int
 287 ext3_check_acl(struct inode *inode, int mask)
 288 {
 289         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 290
 291         if (IS_ERR(acl))
 292                 return PTR_ERR(acl);
 293         if (acl) {
 294                 int error = posix_acl_permission(inode, acl, mask);
 295                 posix_acl_release(acl);
 296                 return error;
 297         }
 298
 299         return -EAGAIN;
 300 }
 301
 302 int
 303 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 304 {
 305         return generic_permission(inode, mask, ext3_check_acl);
 306 }
 307
 308 /*
 309  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 310  *
 311  * dir->i_sem: down
 312  * inode->i_sem: up (access to inode is still exclusive)
 313  */
 314 int
 315 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 316 {
 317         struct posix_acl *acl = NULL;
 318         int error = 0;
 319
 320         if (!S_ISLNK(inode->i_mode)) {
 321                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 322                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 323                         if (IS_ERR(acl))
 324                                 return PTR_ERR(acl);
 325                 }
 326                 if (!acl)
 327                         inode->i_mode &= ~current->fs->umask;
 328         }
 329         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 330                 struct posix_acl *clone;
 331                 mode_t mode;
 332
 333                 if (S_ISDIR(inode->i_mode)) {
 334                         error = ext3_set_acl(handle, inode,
 335                                              ACL_TYPE_DEFAULT, acl);
 336                         if (error)
 337                                 goto cleanup;
 338                 }
 339                 clone = posix_acl_clone(acl, GFP_KERNEL);
 340                 error = -ENOMEM;
 341                 if (!clone)
 342                         goto cleanup;
 343
 344                 mode = inode->i_mode;
 345                 error = posix_acl_create_masq(clone, &mode);
 346                 if (error >= 0) {
 347                         inode->i_mode = mode;
 348                         if (error > 0) {
 349                                 /* This is an extended ACL */
 350                                 error = ext3_set_acl(handle, inode,
 351                                                      ACL_TYPE_ACCESS, clone);
 352                         }
 353                 }
 354                 posix_acl_release(clone);
 355         }
 356 cleanup:
 357         posix_acl_release(acl);
 358         return error;
 359 }
 360
 361 /*
 362  * Does chmod for an inode that may have an Access Control List. The
 363  * inode->i_mode field must be updated to the desired value by the caller
 364  * before calling this function.
 365  * Returns 0 on success, or a negative error number.
 366  *
 367  * We change the ACL rather than storing some ACL entries in the file
 368  * mode permission bits (which would be more efficient), because that
 369  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 370  * for directories) are added. There are no more bits available in the
 371  * file mode.
 372  *
 373  * inode->i_sem: down
 374  */
 375 int
 376 ext3_acl_chmod(struct inode *inode)
 377 {
 378         struct posix_acl *acl, *clone;
 379         int error;
 380
 381         if (S_ISLNK(inode->i_mode))
 382                 return -EOPNOTSUPP;
 383         if (!test_opt(inode->i_sb, POSIX_ACL))
 384                 return 0;
 385         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 386         if (IS_ERR(acl) || !acl)
 387                 return PTR_ERR(acl);
 388         clone = posix_acl_clone(acl, GFP_KERNEL);
 389         posix_acl_release(acl);
 390         if (!clone)
 391                 return -ENOMEM;
 392         error = posix_acl_chmod_masq(clone, inode->i_mode);
 393         if (!error) {
 394                 handle_t *handle;
 395                 int retries = 0;
 396
 397         retry:
 398                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 399                 if (IS_ERR(handle)) {
 400                         error = PTR_ERR(handle);
 401                         ext3_std_error(inode->i_sb, error);
 402                         goto out;
 403                 }
 404                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 405                 ext3_journal_stop(handle);
 406                 if (error == -ENOSPC &&
 407                     ext3_should_retry_alloc(inode->i_sb, &retries))
 408                         goto retry;
 409         }
 410 out:
 411         posix_acl_release(clone);
 412         return error;
 413 }
 414
 415 /*
 416  * Extended attribute handlers
 417  */
 418 static size_t
 419 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
 420                            const char *name, size_t name_len)
 421 {
 422         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 423
 424         if (!test_opt(inode->i_sb, POSIX_ACL))
 425                 return 0;
 426         if (list && size <= list_len)
 427                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 428         return size;
 429 }
 430
 431 static size_t
 432 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
 433                             const char *name, size_t name_len)
 434 {
 435         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 436
 437         if (!test_opt(inode->i_sb, POSIX_ACL))
 438                 return 0;
 439         if (list && size <= list_len)
 440                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 441         return size;
 442 }
 443
 444 static int
 445 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 446 {
 447         struct posix_acl *acl;
 448         int error;
 449
 450         if (!test_opt(inode->i_sb, POSIX_ACL))
 451                 return -EOPNOTSUPP;
 452
 453         acl = ext3_get_acl(inode, type);
 454         if (IS_ERR(acl))
 455                 return PTR_ERR(acl);
 456         if (acl == NULL)
 457                 return -ENODATA;
 458         error = posix_acl_to_xattr(acl, buffer, size);
 459         posix_acl_release(acl);
 460
 461         return error;
 462 }
 463
 464 static int
 465 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 466                           void *buffer, size_t size)
 467 {
 468         if (strcmp(name, "") != 0)
 469                 return -EINVAL;
 470         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 471 }
 472
 473 static int
 474 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 475                            void *buffer, size_t size)
 476 {
 477         if (strcmp(name, "") != 0)
 478                 return -EINVAL;
 479         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 480 }
 481
 482 static int
 483 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 484                    size_t size)
 485 {
 486         handle_t *handle;
 487         struct posix_acl *acl;
 488         int error, retries = 0;
 489
 490         if (!test_opt(inode->i_sb, POSIX_ACL))
 491                 return -EOPNOTSUPP;
 492         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 493                 return -EPERM;
 494
 495         if (value) {
 496                 acl = posix_acl_from_xattr(value, size);
 497                 if (IS_ERR(acl))
 498                         return PTR_ERR(acl);
 499                 else if (acl) {
 500                         error = posix_acl_valid(acl);
 501                         if (error)
 502                                 goto release_and_out;
 503                 }
 504         } else
 505                 acl = NULL;
 506
 507 retry:
 508         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 509         if (IS_ERR(handle))
 510                 return PTR_ERR(handle);
 511         error = ext3_set_acl(handle, inode, type, acl);
 512         ext3_journal_stop(handle);
 513         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 514                 goto retry;
 515
 516 release_and_out:
 517         posix_acl_release(acl);
 518         return error;
 519 }
 520
 521 static int
 522 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 523                           const void *value, size_t size, int flags)
 524 {
 525         if (strcmp(name, "") != 0)
 526                 return -EINVAL;
 527         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 528 }
 529
 530 static int
 531 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 532                            const void *value, size_t size, int flags)
 533 {
 534         if (strcmp(name, "") != 0)
 535                 return -EINVAL;
 536         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 537 }
 538
 539 struct xattr_handler ext3_xattr_acl_access_handler = {
 540         .prefix = XATTR_NAME_ACL_ACCESS,
 541         .list   = ext3_xattr_list_acl_access,
 542         .get    = ext3_xattr_get_acl_access,
 543         .set    = ext3_xattr_set_acl_access,
 544 };
 545
 546 struct xattr_handler ext3_xattr_acl_default_handler = {
 547         .prefix = XATTR_NAME_ACL_DEFAULT,
 548         .list   = ext3_xattr_list_acl_default,
 549         .get    = ext3_xattr_get_acl_default,
 550         .set    = ext3_xattr_set_acl_default,
 551 };