fs/ext3/acl.c

   1 /*
   2  * linux/fs/ext3/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
   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                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  52                                 break;
  53
  54                         case ACL_USER:
  55                         case ACL_GROUP:
  56                                 value = (char *)value + sizeof(ext3_acl_entry);
  57                                 if ((char *)value > end)
  58                                         goto fail;
  59                                 acl->a_entries[n].e_id =
  60                                         le32_to_cpu(entry->e_id);
  61                                 break;
  62
  63                         default:
  64                                 goto fail;
  65                 }
  66         }
  67         if (value != end)
  68                 goto fail;
  69         return acl;
  70
  71 fail:
  72         posix_acl_release(acl);
  73         return ERR_PTR(-EINVAL);
  74 }
  75
  76 /*
  77  * Convert from in-memory to filesystem representation.
  78  */
  79 static void *
  80 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  81 {
  82         ext3_acl_header *ext_acl;
  83         char *e;
  84         size_t n;
  85
  86         *size = ext3_acl_size(acl->a_count);
  87         ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
  88                         sizeof(ext3_acl_entry), GFP_NOFS);
  89         if (!ext_acl)
  90                 return ERR_PTR(-ENOMEM);
  91         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  92         e = (char *)ext_acl + sizeof(ext3_acl_header);
  93         for (n=0; n < acl->a_count; n++) {
  94                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
  95                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
  96                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
  97                 switch(acl->a_entries[n].e_tag) {
  98                         case ACL_USER:
  99                         case ACL_GROUP:
 100                                 entry->e_id =
 101                                         cpu_to_le32(acl->a_entries[n].e_id);
 102                                 e += sizeof(ext3_acl_entry);
 103                                 break;
 104
 105                         case ACL_USER_OBJ:
 106                         case ACL_GROUP_OBJ:
 107                         case ACL_MASK:
 108                         case ACL_OTHER:
 109                                 e += sizeof(ext3_acl_entry_short);
 110                                 break;
 111
 112                         default:
 113                                 goto fail;
 114                 }
 115         }
 116         return (char *)ext_acl;
 117
 118 fail:
 119         kfree(ext_acl);
 120         return ERR_PTR(-EINVAL);
 121 }
 122
 123 /*
 124  * Inode operation get_posix_acl().
 125  *
 126  * inode->i_mutex: don't care
 127  */
 128 struct posix_acl *
 129 ext3_get_acl(struct inode *inode, int type)
 130 {
 131         int name_index;
 132         char *value = NULL;
 133         struct posix_acl *acl;
 134         int retval;
 135
 136         if (!test_opt(inode->i_sb, POSIX_ACL))
 137                 return NULL;
 138
 139         acl = get_cached_acl(inode, type);
 140         if (acl != ACL_NOT_CACHED)
 141                 return acl;
 142
 143         switch (type) {
 144         case ACL_TYPE_ACCESS:
 145                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 146                 break;
 147         case ACL_TYPE_DEFAULT:
 148                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 149                 break;
 150         default:
 151                 BUG();
 152         }
 153
 154         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 155         if (retval > 0) {
 156                 value = kmalloc(retval, GFP_NOFS);
 157                 if (!value)
 158                         return ERR_PTR(-ENOMEM);
 159                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 160         }
 161         if (retval > 0)
 162                 acl = ext3_acl_from_disk(value, retval);
 163         else if (retval == -ENODATA || retval == -ENOSYS)
 164                 acl = NULL;
 165         else
 166                 acl = ERR_PTR(retval);
 167         kfree(value);
 168
 169         if (!IS_ERR(acl))
 170                 set_cached_acl(inode, type, acl);
 171
 172         return acl;
 173 }
 174
 175 /*
 176  * Set the access or default ACL of an inode.
 177  *
 178  * inode->i_mutex: down unless called from ext3_new_inode
 179  */
 180 static int
 181 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 182              struct posix_acl *acl)
 183 {
 184         int name_index;
 185         void *value = NULL;
 186         size_t size = 0;
 187         int error;
 188
 189         if (S_ISLNK(inode->i_mode))
 190                 return -EOPNOTSUPP;
 191
 192         switch(type) {
 193                 case ACL_TYPE_ACCESS:
 194                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 195                         if (acl) {
 196                                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 197                                 if (error < 0)
 198                                         return error;
 199                                 else {
 200                                         inode->i_ctime = CURRENT_TIME_SEC;
 201                                         ext3_mark_inode_dirty(handle, inode);
 202                                         if (error == 0)
 203                                                 acl = NULL;
 204                                 }
 205                         }
 206                         break;
 207
 208                 case ACL_TYPE_DEFAULT:
 209                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 210                         if (!S_ISDIR(inode->i_mode))
 211                                 return acl ? -EACCES : 0;
 212                         break;
 213
 214                 default:
 215                         return -EINVAL;
 216         }
 217         if (acl) {
 218                 value = ext3_acl_to_disk(acl, &size);
 219                 if (IS_ERR(value))
 220                         return (int)PTR_ERR(value);
 221         }
 222
 223         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 224                                       value, size, 0);
 225
 226         kfree(value);
 227
 228         if (!error)
 229                 set_cached_acl(inode, type, acl);
 230
 231         return error;
 232 }
 233
 234 /*
 235  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 236  *
 237  * dir->i_mutex: down
 238  * inode->i_mutex: up (access to inode is still exclusive)
 239  */
 240 int
 241 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 242 {
 243         struct posix_acl *acl = NULL;
 244         int error = 0;
 245
 246         if (!S_ISLNK(inode->i_mode)) {
 247                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 248                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 249                         if (IS_ERR(acl))
 250                                 return PTR_ERR(acl);
 251                 }
 252                 if (!acl)
 253                         inode->i_mode &= ~current_umask();
 254         }
 255         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 256                 if (S_ISDIR(inode->i_mode)) {
 257                         error = ext3_set_acl(handle, inode,
 258                                              ACL_TYPE_DEFAULT, acl);
 259                         if (error)
 260                                 goto cleanup;
 261                 }
 262                 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
 263                 if (error < 0)
 264                         return error;
 265
 266                 if (error > 0) {
 267                         /* This is an extended ACL */
 268                         error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 269                 }
 270         }
 271 cleanup:
 272         posix_acl_release(acl);
 273         return error;
 274 }
 275
 276 /*
 277  * Does chmod for an inode that may have an Access Control List. The
 278  * inode->i_mode field must be updated to the desired value by the caller
 279  * before calling this function.
 280  * Returns 0 on success, or a negative error number.
 281  *
 282  * We change the ACL rather than storing some ACL entries in the file
 283  * mode permission bits (which would be more efficient), because that
 284  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 285  * for directories) are added. There are no more bits available in the
 286  * file mode.
 287  *
 288  * inode->i_mutex: down
 289  */
 290 int
 291 ext3_acl_chmod(struct inode *inode)
 292 {
 293         struct posix_acl *acl;
 294         handle_t *handle;
 295         int retries = 0;
 296         int error;
 297
 298         if (S_ISLNK(inode->i_mode))
 299                 return -EOPNOTSUPP;
 300         if (!test_opt(inode->i_sb, POSIX_ACL))
 301                 return 0;
 302         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 303         if (IS_ERR(acl) || !acl)
 304                 return PTR_ERR(acl);
 305         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 306         if (error)
 307                 return error;
 308 retry:
 309         handle = ext3_journal_start(inode,
 310                         EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 311         if (IS_ERR(handle)) {
 312                 error = PTR_ERR(handle);
 313                 ext3_std_error(inode->i_sb, error);
 314                 goto out;
 315         }
 316         error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 317         ext3_journal_stop(handle);
 318         if (error == -ENOSPC &&
 319             ext3_should_retry_alloc(inode->i_sb, &retries))
 320                 goto retry;
 321 out:
 322         posix_acl_release(acl);
 323         return error;
 324 }
 325
 326 /*
 327  * Extended attribute handlers
 328  */
 329 static size_t
 330 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 331                            const char *name, size_t name_len, int type)
 332 {
 333         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 334
 335         if (!test_opt(dentry->d_sb, POSIX_ACL))
 336                 return 0;
 337         if (list && size <= list_len)
 338                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 339         return size;
 340 }
 341
 342 static size_t
 343 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 344                             const char *name, size_t name_len, int type)
 345 {
 346         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 347
 348         if (!test_opt(dentry->d_sb, POSIX_ACL))
 349                 return 0;
 350         if (list && size <= list_len)
 351                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 352         return size;
 353 }
 354
 355 static int
 356 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 357                    size_t size, int type)
 358 {
 359         struct posix_acl *acl;
 360         int error;
 361
 362         if (strcmp(name, "") != 0)
 363                 return -EINVAL;
 364         if (!test_opt(dentry->d_sb, POSIX_ACL))
 365                 return -EOPNOTSUPP;
 366
 367         acl = ext3_get_acl(dentry->d_inode, type);
 368         if (IS_ERR(acl))
 369                 return PTR_ERR(acl);
 370         if (acl == NULL)
 371                 return -ENODATA;
 372         error = posix_acl_to_xattr(acl, buffer, size);
 373         posix_acl_release(acl);
 374
 375         return error;
 376 }
 377
 378 static int
 379 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 380                    size_t size, int flags, int type)
 381 {
 382         struct inode *inode = dentry->d_inode;
 383         handle_t *handle;
 384         struct posix_acl *acl;
 385         int error, retries = 0;
 386
 387         if (strcmp(name, "") != 0)
 388                 return -EINVAL;
 389         if (!test_opt(inode->i_sb, POSIX_ACL))
 390                 return -EOPNOTSUPP;
 391         if (!inode_owner_or_capable(inode))
 392                 return -EPERM;
 393
 394         if (value) {
 395                 acl = posix_acl_from_xattr(value, size);
 396                 if (IS_ERR(acl))
 397                         return PTR_ERR(acl);
 398                 else if (acl) {
 399                         error = posix_acl_valid(acl);
 400                         if (error)
 401                                 goto release_and_out;
 402                 }
 403         } else
 404                 acl = NULL;
 405
 406 retry:
 407         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 408         if (IS_ERR(handle))
 409                 return PTR_ERR(handle);
 410         error = ext3_set_acl(handle, inode, type, acl);
 411         ext3_journal_stop(handle);
 412         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 413                 goto retry;
 414
 415 release_and_out:
 416         posix_acl_release(acl);
 417         return error;
 418 }
 419
 420 const struct xattr_handler ext3_xattr_acl_access_handler = {
 421         .prefix = POSIX_ACL_XATTR_ACCESS,
 422         .flags  = ACL_TYPE_ACCESS,
 423         .list   = ext3_xattr_list_acl_access,
 424         .get    = ext3_xattr_get_acl,
 425         .set    = ext3_xattr_set_acl,
 426 };
 427
 428 const struct xattr_handler ext3_xattr_acl_default_handler = {
 429         .prefix = POSIX_ACL_XATTR_DEFAULT,
 430         .flags  = ACL_TYPE_DEFAULT,
 431         .list   = ext3_xattr_list_acl_default,
 432         .get    = ext3_xattr_get_acl,
 433         .set    = ext3_xattr_set_acl,
 434 };