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 static int
 291 ext3_check_acl(struct inode *inode, int mask)
 292 {
 293         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 294
 295         if (acl) {
 296                 int error = posix_acl_permission(inode, acl, mask);
 297                 posix_acl_release(acl);
 298                 return error;
 299         }
 300
 301         return -EAGAIN;
 302 }
 303
 304 int
 305 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 306 {
 307         return generic_permission(inode, mask, ext3_check_acl);
 308 }
 309
 310 /*
 311  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 312  *
 313  * dir->i_sem: down
 314  * inode->i_sem: up (access to inode is still exclusive)
 315  */
 316 int
 317 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 318 {
 319         struct posix_acl *acl = NULL;
 320         int error = 0;
 321
 322         if (!S_ISLNK(inode->i_mode)) {
 323                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 324                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 325                         if (IS_ERR(acl))
 326                                 return PTR_ERR(acl);
 327                 }
 328                 if (!acl)
 329                         inode->i_mode &= ~current->fs->umask;
 330         }
 331         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 332                 struct posix_acl *clone;
 333                 mode_t mode;
 334
 335                 if (S_ISDIR(inode->i_mode)) {
 336                         error = ext3_set_acl(handle, inode,
 337                                              ACL_TYPE_DEFAULT, acl);
 338                         if (error)
 339                                 goto cleanup;
 340                 }
 341                 clone = posix_acl_clone(acl, GFP_KERNEL);
 342                 error = -ENOMEM;
 343                 if (!clone)
 344                         goto cleanup;
 345
 346                 mode = inode->i_mode;
 347                 error = posix_acl_create_masq(clone, &mode);
 348                 if (error >= 0) {
 349                         inode->i_mode = mode;
 350                         if (error > 0) {
 351                                 /* This is an extended ACL */
 352                                 error = ext3_set_acl(handle, inode,
 353                                                      ACL_TYPE_ACCESS, clone);
 354                         }
 355                 }
 356                 posix_acl_release(clone);
 357         }
 358 cleanup:
 359         posix_acl_release(acl);
 360         return error;
 361 }
 362
 363 /*
 364  * Does chmod for an inode that may have an Access Control List. The
 365  * inode->i_mode field must be updated to the desired value by the caller
 366  * before calling this function.
 367  * Returns 0 on success, or a negative error number.
 368  *
 369  * We change the ACL rather than storing some ACL entries in the file
 370  * mode permission bits (which would be more efficient), because that
 371  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 372  * for directories) are added. There are no more bits available in the
 373  * file mode.
 374  *
 375  * inode->i_sem: down
 376  */
 377 int
 378 ext3_acl_chmod(struct inode *inode)
 379 {
 380         struct posix_acl *acl, *clone;
 381         int error;
 382
 383         if (S_ISLNK(inode->i_mode))
 384                 return -EOPNOTSUPP;
 385         if (!test_opt(inode->i_sb, POSIX_ACL))
 386                 return 0;
 387         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 388         if (IS_ERR(acl) || !acl)
 389                 return PTR_ERR(acl);
 390         clone = posix_acl_clone(acl, GFP_KERNEL);
 391         posix_acl_release(acl);
 392         if (!clone)
 393                 return -ENOMEM;
 394         error = posix_acl_chmod_masq(clone, inode->i_mode);
 395         if (!error) {
 396                 handle_t *handle;
 397                 int retries = 0;
 398
 399         retry:
 400                 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 401                 if (IS_ERR(handle)) {
 402                         error = PTR_ERR(handle);
 403                         ext3_std_error(inode->i_sb, error);
 404                         goto out;
 405                 }
 406                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 407                 ext3_journal_stop(handle);
 408                 if (error == -ENOSPC &&
 409                     ext3_should_retry_alloc(inode->i_sb, &retries))
 410                         goto retry;
 411         }
 412 out:
 413         posix_acl_release(clone);
 414         return error;
 415 }
 416
 417 /*
 418  * Extended attribute handlers
 419  */
 420 static size_t
 421 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
 422                            const char *name, size_t name_len)
 423 {
 424         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 425
 426         if (!test_opt(inode->i_sb, POSIX_ACL))
 427                 return 0;
 428         if (list && size <= list_len)
 429                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 430         return size;
 431 }
 432
 433 static size_t
 434 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
 435                             const char *name, size_t name_len)
 436 {
 437         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 438
 439         if (!test_opt(inode->i_sb, POSIX_ACL))
 440                 return 0;
 441         if (list && size <= list_len)
 442                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 443         return size;
 444 }
 445
 446 static int
 447 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 448 {
 449         struct posix_acl *acl;
 450         int error;
 451
 452         if (!test_opt(inode->i_sb, POSIX_ACL))
 453                 return -EOPNOTSUPP;
 454
 455         acl = ext3_get_acl(inode, type);
 456         if (IS_ERR(acl))
 457                 return PTR_ERR(acl);
 458         if (acl == NULL)
 459                 return -ENODATA;
 460         error = posix_acl_to_xattr(acl, buffer, size);
 461         posix_acl_release(acl);
 462
 463         return error;
 464 }
 465
 466 static int
 467 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 468                           void *buffer, size_t size)
 469 {
 470         if (strcmp(name, "") != 0)
 471                 return -EINVAL;
 472         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 473 }
 474
 475 static int
 476 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 477                            void *buffer, size_t size)
 478 {
 479         if (strcmp(name, "") != 0)
 480                 return -EINVAL;
 481         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 482 }
 483
 484 static int
 485 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 486                    size_t size)
 487 {
 488         handle_t *handle;
 489         struct posix_acl *acl;
 490         int error, retries = 0;
 491
 492         if (!test_opt(inode->i_sb, POSIX_ACL))
 493                 return -EOPNOTSUPP;
 494         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 495                 return -EPERM;
 496
 497         if (value) {
 498                 acl = posix_acl_from_xattr(value, size);
 499                 if (IS_ERR(acl))
 500                         return PTR_ERR(acl);
 501                 else if (acl) {
 502                         error = posix_acl_valid(acl);
 503                         if (error)
 504                                 goto release_and_out;
 505                 }
 506         } else
 507                 acl = NULL;
 508
 509 retry:
 510         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
 511         if (IS_ERR(handle))
 512                 return PTR_ERR(handle);
 513         error = ext3_set_acl(handle, inode, type, acl);
 514         ext3_journal_stop(handle);
 515         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 516                 goto retry;
 517
 518 release_and_out:
 519         posix_acl_release(acl);
 520         return error;
 521 }
 522
 523 static int
 524 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 525                           const void *value, size_t size, int flags)
 526 {
 527         if (strcmp(name, "") != 0)
 528                 return -EINVAL;
 529         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 530 }
 531
 532 static int
 533 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 534                            const void *value, size_t size, int flags)
 535 {
 536         if (strcmp(name, "") != 0)
 537                 return -EINVAL;
 538         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 539 }
 540
 541 struct xattr_handler ext3_xattr_acl_access_handler = {
 542         .prefix = XATTR_NAME_ACL_ACCESS,
 543         .list   = ext3_xattr_list_acl_access,
 544         .get    = ext3_xattr_get_acl_access,
 545         .set    = ext3_xattr_set_acl_access,
 546 };
 547
 548 struct xattr_handler ext3_xattr_acl_default_handler = {
 549         .prefix = XATTR_NAME_ACL_DEFAULT,
 550         .list   = ext3_xattr_list_acl_default,
 551         .get    = ext3_xattr_get_acl_default,
 552         .set    = ext3_xattr_set_acl_default,
 553 };