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 "ext3.h"
   8 #include "xattr.h"
   9 #include "acl.h"
  10
  11 /*
  12  * Convert from filesystem to in-memory representation.
  13  */
  14 static struct posix_acl *
  15 ext3_acl_from_disk(const void *value, size_t size)
  16 {
  17         const char *end = (char *)value + size;
  18         int n, count;
  19         struct posix_acl *acl;
  20
  21         if (!value)
  22                 return NULL;
  23         if (size < sizeof(ext3_acl_header))
  24                  return ERR_PTR(-EINVAL);
  25         if (((ext3_acl_header *)value)->a_version !=
  26             cpu_to_le32(EXT3_ACL_VERSION))
  27                 return ERR_PTR(-EINVAL);
  28         value = (char *)value + sizeof(ext3_acl_header);
  29         count = ext3_acl_count(size);
  30         if (count < 0)
  31                 return ERR_PTR(-EINVAL);
  32         if (count == 0)
  33                 return NULL;
  34         acl = posix_acl_alloc(count, GFP_NOFS);
  35         if (!acl)
  36                 return ERR_PTR(-ENOMEM);
  37         for (n=0; n < count; n++) {
  38                 ext3_acl_entry *entry =
  39                         (ext3_acl_entry *)value;
  40                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  41                         goto fail;
  42                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  43                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  44                 switch(acl->a_entries[n].e_tag) {
  45                         case ACL_USER_OBJ:
  46                         case ACL_GROUP_OBJ:
  47                         case ACL_MASK:
  48                         case ACL_OTHER:
  49                                 value = (char *)value +
  50                                         sizeof(ext3_acl_entry_short);
  51                                 break;
  52
  53                         case ACL_USER:
  54                                 value = (char *)value + sizeof(ext3_acl_entry);
  55                                 if ((char *)value > end)
  56                                         goto fail;
  57                                 acl->a_entries[n].e_uid =
  58                                         make_kuid(&init_user_ns,
  59                                                   le32_to_cpu(entry->e_id));
  60                                 break;
  61                         case ACL_GROUP:
  62                                 value = (char *)value + sizeof(ext3_acl_entry);
  63                                 if ((char *)value > end)
  64                                         goto fail;
  65                                 acl->a_entries[n].e_gid =
  66                                         make_kgid(&init_user_ns,
  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 = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
  95                         sizeof(ext3_acl_entry), GFP_NOFS);
  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                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 102                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
 103                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 104                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 105                 switch(acl_e->e_tag) {
 106                         case ACL_USER:
 107                                 entry->e_id = cpu_to_le32(
 108                                         from_kuid(&init_user_ns, acl_e->e_uid));
 109                                 e += sizeof(ext3_acl_entry);
 110                                 break;
 111                         case ACL_GROUP:
 112                                 entry->e_id = cpu_to_le32(
 113                                         from_kgid(&init_user_ns, acl_e->e_gid));
 114                                 e += sizeof(ext3_acl_entry);
 115                                 break;
 116
 117                         case ACL_USER_OBJ:
 118                         case ACL_GROUP_OBJ:
 119                         case ACL_MASK:
 120                         case ACL_OTHER:
 121                                 e += sizeof(ext3_acl_entry_short);
 122                                 break;
 123
 124                         default:
 125                                 goto fail;
 126                 }
 127         }
 128         return (char *)ext_acl;
 129
 130 fail:
 131         kfree(ext_acl);
 132         return ERR_PTR(-EINVAL);
 133 }
 134
 135 /*
 136  * Inode operation get_posix_acl().
 137  *
 138  * inode->i_mutex: don't care
 139  */
 140 struct posix_acl *
 141 ext3_get_acl(struct inode *inode, int type)
 142 {
 143         int name_index;
 144         char *value = NULL;
 145         struct posix_acl *acl;
 146         int retval;
 147
 148         if (!test_opt(inode->i_sb, POSIX_ACL))
 149                 return NULL;
 150
 151         acl = get_cached_acl(inode, type);
 152         if (acl != ACL_NOT_CACHED)
 153                 return acl;
 154
 155         switch (type) {
 156         case ACL_TYPE_ACCESS:
 157                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 158                 break;
 159         case ACL_TYPE_DEFAULT:
 160                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 161                 break;
 162         default:
 163                 BUG();
 164         }
 165
 166         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 167         if (retval > 0) {
 168                 value = kmalloc(retval, GFP_NOFS);
 169                 if (!value)
 170                         return ERR_PTR(-ENOMEM);
 171                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 172         }
 173         if (retval > 0)
 174                 acl = ext3_acl_from_disk(value, retval);
 175         else if (retval == -ENODATA || retval == -ENOSYS)
 176                 acl = NULL;
 177         else
 178                 acl = ERR_PTR(retval);
 179         kfree(value);
 180
 181         if (!IS_ERR(acl))
 182                 set_cached_acl(inode, type, acl);
 183
 184         return acl;
 185 }
 186
 187 /*
 188  * Set the access or default ACL of an inode.
 189  *
 190  * inode->i_mutex: down unless called from ext3_new_inode
 191  */
 192 static int
 193 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 194              struct posix_acl *acl)
 195 {
 196         int name_index;
 197         void *value = NULL;
 198         size_t size = 0;
 199         int error;
 200
 201         if (S_ISLNK(inode->i_mode))
 202                 return -EOPNOTSUPP;
 203
 204         switch(type) {
 205                 case ACL_TYPE_ACCESS:
 206                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 207                         if (acl) {
 208                                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 209                                 if (error < 0)
 210                                         return error;
 211                                 else {
 212                                         inode->i_ctime = CURRENT_TIME_SEC;
 213                                         ext3_mark_inode_dirty(handle, inode);
 214                                         if (error == 0)
 215                                                 acl = NULL;
 216                                 }
 217                         }
 218                         break;
 219
 220                 case ACL_TYPE_DEFAULT:
 221                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 222                         if (!S_ISDIR(inode->i_mode))
 223                                 return acl ? -EACCES : 0;
 224                         break;
 225
 226                 default:
 227                         return -EINVAL;
 228         }
 229         if (acl) {
 230                 value = ext3_acl_to_disk(acl, &size);
 231                 if (IS_ERR(value))
 232                         return (int)PTR_ERR(value);
 233         }
 234
 235         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 236                                       value, size, 0);
 237
 238         kfree(value);
 239
 240         if (!error)
 241                 set_cached_acl(inode, type, acl);
 242
 243         return error;
 244 }
 245
 246 /*
 247  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 248  *
 249  * dir->i_mutex: down
 250  * inode->i_mutex: up (access to inode is still exclusive)
 251  */
 252 int
 253 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 254 {
 255         struct posix_acl *acl = NULL;
 256         int error = 0;
 257
 258         if (!S_ISLNK(inode->i_mode)) {
 259                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 260                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 261                         if (IS_ERR(acl))
 262                                 return PTR_ERR(acl);
 263                 }
 264                 if (!acl)
 265                         inode->i_mode &= ~current_umask();
 266         }
 267         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 268                 if (S_ISDIR(inode->i_mode)) {
 269                         error = ext3_set_acl(handle, inode,
 270                                              ACL_TYPE_DEFAULT, acl);
 271                         if (error)
 272                                 goto cleanup;
 273                 }
 274                 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
 275                 if (error < 0)
 276                         return error;
 277
 278                 if (error > 0) {
 279                         /* This is an extended ACL */
 280                         error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 281                 }
 282         }
 283 cleanup:
 284         posix_acl_release(acl);
 285         return error;
 286 }
 287
 288 /*
 289  * Does chmod for an inode that may have an Access Control List. The
 290  * inode->i_mode field must be updated to the desired value by the caller
 291  * before calling this function.
 292  * Returns 0 on success, or a negative error number.
 293  *
 294  * We change the ACL rather than storing some ACL entries in the file
 295  * mode permission bits (which would be more efficient), because that
 296  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 297  * for directories) are added. There are no more bits available in the
 298  * file mode.
 299  *
 300  * inode->i_mutex: down
 301  */
 302 int
 303 ext3_acl_chmod(struct inode *inode)
 304 {
 305         struct posix_acl *acl;
 306         handle_t *handle;
 307         int retries = 0;
 308         int error;
 309
 310         if (S_ISLNK(inode->i_mode))
 311                 return -EOPNOTSUPP;
 312         if (!test_opt(inode->i_sb, POSIX_ACL))
 313                 return 0;
 314         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 315         if (IS_ERR(acl) || !acl)
 316                 return PTR_ERR(acl);
 317         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 318         if (error)
 319                 return error;
 320 retry:
 321         handle = ext3_journal_start(inode,
 322                         EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 323         if (IS_ERR(handle)) {
 324                 error = PTR_ERR(handle);
 325                 ext3_std_error(inode->i_sb, error);
 326                 goto out;
 327         }
 328         error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 329         ext3_journal_stop(handle);
 330         if (error == -ENOSPC &&
 331             ext3_should_retry_alloc(inode->i_sb, &retries))
 332                 goto retry;
 333 out:
 334         posix_acl_release(acl);
 335         return error;
 336 }
 337
 338 /*
 339  * Extended attribute handlers
 340  */
 341 static size_t
 342 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 343                            const char *name, size_t name_len, int type)
 344 {
 345         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 346
 347         if (!test_opt(dentry->d_sb, POSIX_ACL))
 348                 return 0;
 349         if (list && size <= list_len)
 350                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 351         return size;
 352 }
 353
 354 static size_t
 355 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 356                             const char *name, size_t name_len, int type)
 357 {
 358         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 359
 360         if (!test_opt(dentry->d_sb, POSIX_ACL))
 361                 return 0;
 362         if (list && size <= list_len)
 363                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 364         return size;
 365 }
 366
 367 static int
 368 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 369                    size_t size, int type)
 370 {
 371         struct posix_acl *acl;
 372         int error;
 373
 374         if (strcmp(name, "") != 0)
 375                 return -EINVAL;
 376         if (!test_opt(dentry->d_sb, POSIX_ACL))
 377                 return -EOPNOTSUPP;
 378
 379         acl = ext3_get_acl(dentry->d_inode, type);
 380         if (IS_ERR(acl))
 381                 return PTR_ERR(acl);
 382         if (acl == NULL)
 383                 return -ENODATA;
 384         error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 385         posix_acl_release(acl);
 386
 387         return error;
 388 }
 389
 390 static int
 391 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 392                    size_t size, int flags, int type)
 393 {
 394         struct inode *inode = dentry->d_inode;
 395         handle_t *handle;
 396         struct posix_acl *acl;
 397         int error, retries = 0;
 398
 399         if (strcmp(name, "") != 0)
 400                 return -EINVAL;
 401         if (!test_opt(inode->i_sb, POSIX_ACL))
 402                 return -EOPNOTSUPP;
 403         if (!inode_owner_or_capable(inode))
 404                 return -EPERM;
 405
 406         if (value) {
 407                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 408                 if (IS_ERR(acl))
 409                         return PTR_ERR(acl);
 410                 else if (acl) {
 411                         error = posix_acl_valid(acl);
 412                         if (error)
 413                                 goto release_and_out;
 414                 }
 415         } else
 416                 acl = NULL;
 417
 418 retry:
 419         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 420         if (IS_ERR(handle))
 421                 return PTR_ERR(handle);
 422         error = ext3_set_acl(handle, inode, type, acl);
 423         ext3_journal_stop(handle);
 424         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 425                 goto retry;
 426
 427 release_and_out:
 428         posix_acl_release(acl);
 429         return error;
 430 }
 431
 432 const struct xattr_handler ext3_xattr_acl_access_handler = {
 433         .prefix = POSIX_ACL_XATTR_ACCESS,
 434         .flags  = ACL_TYPE_ACCESS,
 435         .list   = ext3_xattr_list_acl_access,
 436         .get    = ext3_xattr_get_acl,
 437         .set    = ext3_xattr_set_acl,
 438 };
 439
 440 const struct xattr_handler ext3_xattr_acl_default_handler = {
 441         .prefix = POSIX_ACL_XATTR_DEFAULT,
 442         .flags  = ACL_TYPE_DEFAULT,
 443         .list   = ext3_xattr_list_acl_default,
 444         .get    = ext3_xattr_get_acl,
 445         .set    = ext3_xattr_set_acl,
 446 };