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         kfree(value);
 201
 202         if (!IS_ERR(acl)) {
 203                 switch(type) {
 204                         case ACL_TYPE_ACCESS:
 205                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 206                                 break;
 207
 208                         case ACL_TYPE_DEFAULT:
 209                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 210                                 break;
 211                 }
 212         }
 213         return acl;
 214 }
 215
 216 /*
 217  * Set the access or default ACL of an inode.
 218  *
 219  * inode->i_sem: down unless called from ext3_new_inode
 220  */
 221 static int
 222 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 223              struct posix_acl *acl)
 224 {
 225         struct ext3_inode_info *ei = EXT3_I(inode);
 226         int name_index;
 227         void *value = NULL;
 228         size_t size;
 229         int error;
 230
 231         if (S_ISLNK(inode->i_mode))
 232                 return -EOPNOTSUPP;
 233
 234         switch(type) {
 235                 case ACL_TYPE_ACCESS:
 236                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 237                         if (acl) {
 238                                 mode_t mode = inode->i_mode;
 239                                 error = posix_acl_equiv_mode(acl, &mode);
 240                                 if (error < 0)
 241                                         return error;
 242                                 else {
 243                                         inode->i_mode = mode;
 244                                         ext3_mark_inode_dirty(handle, inode);
 245                                         if (error == 0)
 246                                                 acl = NULL;
 247                                 }
 248                         }
 249                         break;
 250
 251                 case ACL_TYPE_DEFAULT:
 252                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 253                         if (!S_ISDIR(inode->i_mode))
 254                                 return acl ? -EACCES : 0;
 255                         break;
 256
 257                 default:
 258                         return -EINVAL;
 259         }
 260         if (acl) {
 261                 value = ext3_acl_to_disk(acl, &size);
 262                 if (IS_ERR(value))
 263                         return (int)PTR_ERR(value);
 264         }
 265
 266         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 267                                       value, size, 0);
 268
 269         kfree(value);
 270         if (!error) {
 271                 switch(type) {
 272                         case ACL_TYPE_ACCESS:
 273                                 ext3_iset_acl(inode, &ei->i_acl, acl);
 274                                 break;
 275
 276                         case ACL_TYPE_DEFAULT:
 277                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
 278                                 break;
 279                 }
 280         }
 281         return error;
 282 }
 283
 284 static int
 285 ext3_check_acl(struct inode *inode, int mask)
 286 {
 287         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 288
 289         if (IS_ERR(acl))
 290                 return PTR_ERR(acl);
 291         if (acl) {
 292                 int error = posix_acl_permission(inode, acl, mask);
 293                 posix_acl_release(acl);
 294                 return error;
 295         }
 296
 297         return -EAGAIN;
 298 }
 299
 300 int
 301 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
 302 {
 303         return generic_permission(inode, mask, ext3_check_acl);
 304 }
 305
 306 /*
 307  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 308  *
 309  * dir->i_sem: down
 310  * inode->i_sem: up (access to inode is still exclusive)
 311  */
 312 int
 313 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 314 {
 315         struct posix_acl *acl = NULL;
 316         int error = 0;
 317
 318         if (!S_ISLNK(inode->i_mode)) {
 319                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 320                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 321                         if (IS_ERR(acl))
 322                                 return PTR_ERR(acl);
 323                 }
 324                 if (!acl)
 325                         inode->i_mode &= ~current->fs->umask;
 326         }
 327         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 328                 struct posix_acl *clone;
 329                 mode_t mode;
 330
 331                 if (S_ISDIR(inode->i_mode)) {
 332                         error = ext3_set_acl(handle, inode,
 333                                              ACL_TYPE_DEFAULT, acl);
 334                         if (error)
 335                                 goto cleanup;
 336                 }
 337                 clone = posix_acl_clone(acl, GFP_KERNEL);
 338                 error = -ENOMEM;
 339                 if (!clone)
 340                         goto cleanup;
 341
 342                 mode = inode->i_mode;
 343                 error = posix_acl_create_masq(clone, &mode);
 344                 if (error >= 0) {
 345                         inode->i_mode = mode;
 346                         if (error > 0) {
 347                                 /* This is an extended ACL */
 348                                 error = ext3_set_acl(handle, inode,
 349                                                      ACL_TYPE_ACCESS, clone);
 350                         }
 351                 }
 352                 posix_acl_release(clone);
 353         }
 354 cleanup:
 355         posix_acl_release(acl);
 356         return error;
 357 }
 358
 359 /*
 360  * Does chmod for an inode that may have an Access Control List. The
 361  * inode->i_mode field must be updated to the desired value by the caller
 362  * before calling this function.
 363  * Returns 0 on success, or a negative error number.
 364  *
 365  * We change the ACL rather than storing some ACL entries in the file
 366  * mode permission bits (which would be more efficient), because that
 367  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 368  * for directories) are added. There are no more bits available in the
 369  * file mode.
 370  *
 371  * inode->i_sem: down
 372  */
 373 int
 374 ext3_acl_chmod(struct inode *inode)
 375 {
 376         struct posix_acl *acl, *clone;
 377         int error;
 378
 379         if (S_ISLNK(inode->i_mode))
 380                 return -EOPNOTSUPP;
 381         if (!test_opt(inode->i_sb, POSIX_ACL))
 382                 return 0;
 383         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 384         if (IS_ERR(acl) || !acl)
 385                 return PTR_ERR(acl);
 386         clone = posix_acl_clone(acl, GFP_KERNEL);
 387         posix_acl_release(acl);
 388         if (!clone)
 389                 return -ENOMEM;
 390         error = posix_acl_chmod_masq(clone, inode->i_mode);
 391         if (!error) {
 392                 handle_t *handle;
 393                 int retries = 0;
 394
 395         retry:
 396                 handle = ext3_journal_start(inode,
 397                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 398                 if (IS_ERR(handle)) {
 399                         error = PTR_ERR(handle);
 400                         ext3_std_error(inode->i_sb, error);
 401                         goto out;
 402                 }
 403                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 404                 ext3_journal_stop(handle);
 405                 if (error == -ENOSPC &&
 406                     ext3_should_retry_alloc(inode->i_sb, &retries))
 407                         goto retry;
 408         }
 409 out:
 410         posix_acl_release(clone);
 411         return error;
 412 }
 413
 414 /*
 415  * Extended attribute handlers
 416  */
 417 static size_t
 418 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
 419                            const char *name, size_t name_len)
 420 {
 421         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 422
 423         if (!test_opt(inode->i_sb, POSIX_ACL))
 424                 return 0;
 425         if (list && size <= list_len)
 426                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 427         return size;
 428 }
 429
 430 static size_t
 431 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
 432                             const char *name, size_t name_len)
 433 {
 434         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 435
 436         if (!test_opt(inode->i_sb, POSIX_ACL))
 437                 return 0;
 438         if (list && size <= list_len)
 439                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 440         return size;
 441 }
 442
 443 static int
 444 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 445 {
 446         struct posix_acl *acl;
 447         int error;
 448
 449         if (!test_opt(inode->i_sb, POSIX_ACL))
 450                 return -EOPNOTSUPP;
 451
 452         acl = ext3_get_acl(inode, type);
 453         if (IS_ERR(acl))
 454                 return PTR_ERR(acl);
 455         if (acl == NULL)
 456                 return -ENODATA;
 457         error = posix_acl_to_xattr(acl, buffer, size);
 458         posix_acl_release(acl);
 459
 460         return error;
 461 }
 462
 463 static int
 464 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
 465                           void *buffer, size_t size)
 466 {
 467         if (strcmp(name, "") != 0)
 468                 return -EINVAL;
 469         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 470 }
 471
 472 static int
 473 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
 474                            void *buffer, size_t size)
 475 {
 476         if (strcmp(name, "") != 0)
 477                 return -EINVAL;
 478         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 479 }
 480
 481 static int
 482 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
 483                    size_t size)
 484 {
 485         handle_t *handle;
 486         struct posix_acl *acl;
 487         int error, retries = 0;
 488
 489         if (!test_opt(inode->i_sb, POSIX_ACL))
 490                 return -EOPNOTSUPP;
 491         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 492                 return -EPERM;
 493
 494         if (value) {
 495                 acl = posix_acl_from_xattr(value, size);
 496                 if (IS_ERR(acl))
 497                         return PTR_ERR(acl);
 498                 else if (acl) {
 499                         error = posix_acl_valid(acl);
 500                         if (error)
 501                                 goto release_and_out;
 502                 }
 503         } else
 504                 acl = NULL;
 505
 506 retry:
 507         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 508         if (IS_ERR(handle))
 509                 return PTR_ERR(handle);
 510         error = ext3_set_acl(handle, inode, type, acl);
 511         ext3_journal_stop(handle);
 512         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 513                 goto retry;
 514
 515 release_and_out:
 516         posix_acl_release(acl);
 517         return error;
 518 }
 519
 520 static int
 521 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
 522                           const void *value, size_t size, int flags)
 523 {
 524         if (strcmp(name, "") != 0)
 525                 return -EINVAL;
 526         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 527 }
 528
 529 static int
 530 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
 531                            const void *value, size_t size, int flags)
 532 {
 533         if (strcmp(name, "") != 0)
 534                 return -EINVAL;
 535         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 536 }
 537
 538 struct xattr_handler ext3_xattr_acl_access_handler = {
 539         .prefix = POSIX_ACL_XATTR_ACCESS,
 540         .list   = ext3_xattr_list_acl_access,
 541         .get    = ext3_xattr_get_acl_access,
 542         .set    = ext3_xattr_set_acl_access,
 543 };
 544
 545 struct xattr_handler ext3_xattr_acl_default_handler = {
 546         .prefix = POSIX_ACL_XATTR_DEFAULT,
 547         .list   = ext3_xattr_list_acl_default,
 548         .get    = ext3_xattr_get_acl_default,
 549         .set    = ext3_xattr_set_acl_default,
 550 };