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/capability.h>
  11 #include <linux/fs.h>
  12 #include <linux/ext3_jbd.h>
  13 #include <linux/ext3_fs.h>
  14 #include "xattr.h"
  15 #include "acl.h"
  16
  17 /*
  18  * Convert from filesystem to in-memory representation.
  19  */
  20 static struct posix_acl *
  21 ext3_acl_from_disk(const void *value, size_t size)
  22 {
  23         const char *end = (char *)value + size;
  24         int n, count;
  25         struct posix_acl *acl;
  26
  27         if (!value)
  28                 return NULL;
  29         if (size < sizeof(ext3_acl_header))
  30                  return ERR_PTR(-EINVAL);
  31         if (((ext3_acl_header *)value)->a_version !=
  32             cpu_to_le32(EXT3_ACL_VERSION))
  33                 return ERR_PTR(-EINVAL);
  34         value = (char *)value + sizeof(ext3_acl_header);
  35         count = ext3_acl_count(size);
  36         if (count < 0)
  37                 return ERR_PTR(-EINVAL);
  38         if (count == 0)
  39                 return NULL;
  40         acl = posix_acl_alloc(count, GFP_NOFS);
  41         if (!acl)
  42                 return ERR_PTR(-ENOMEM);
  43         for (n=0; n < count; n++) {
  44                 ext3_acl_entry *entry =
  45                         (ext3_acl_entry *)value;
  46                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  47                         goto fail;
  48                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  49                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  50                 switch(acl->a_entries[n].e_tag) {
  51                         case ACL_USER_OBJ:
  52                         case ACL_GROUP_OBJ:
  53                         case ACL_MASK:
  54                         case ACL_OTHER:
  55                                 value = (char *)value +
  56                                         sizeof(ext3_acl_entry_short);
  57                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  58                                 break;
  59
  60                         case ACL_USER:
  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_id =
  66                                         le32_to_cpu(entry->e_id);
  67                                 break;
  68
  69                         default:
  70                                 goto fail;
  71                 }
  72         }
  73         if (value != end)
  74                 goto fail;
  75         return acl;
  76
  77 fail:
  78         posix_acl_release(acl);
  79         return ERR_PTR(-EINVAL);
  80 }
  81
  82 /*
  83  * Convert from in-memory to filesystem representation.
  84  */
  85 static void *
  86 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  87 {
  88         ext3_acl_header *ext_acl;
  89         char *e;
  90         size_t n;
  91
  92         *size = ext3_acl_size(acl->a_count);
  93         ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
  94                         sizeof(ext3_acl_entry), GFP_NOFS);
  95         if (!ext_acl)
  96                 return ERR_PTR(-ENOMEM);
  97         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  98         e = (char *)ext_acl + sizeof(ext3_acl_header);
  99         for (n=0; n < acl->a_count; n++) {
 100                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
 101                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 102                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 103                 switch(acl->a_entries[n].e_tag) {
 104                         case ACL_USER:
 105                         case ACL_GROUP:
 106                                 entry->e_id =
 107                                         cpu_to_le32(acl->a_entries[n].e_id);
 108                                 e += sizeof(ext3_acl_entry);
 109                                 break;
 110
 111                         case ACL_USER_OBJ:
 112                         case ACL_GROUP_OBJ:
 113                         case ACL_MASK:
 114                         case ACL_OTHER:
 115                                 e += sizeof(ext3_acl_entry_short);
 116                                 break;
 117
 118                         default:
 119                                 goto fail;
 120                 }
 121         }
 122         return (char *)ext_acl;
 123
 124 fail:
 125         kfree(ext_acl);
 126         return ERR_PTR(-EINVAL);
 127 }
 128
 129 /*
 130  * Inode operation get_posix_acl().
 131  *
 132  * inode->i_mutex: don't care
 133  */
 134 static struct posix_acl *
 135 ext3_get_acl(struct inode *inode, int type)
 136 {
 137         int name_index;
 138         char *value = NULL;
 139         struct posix_acl *acl;
 140         int retval;
 141
 142         if (!test_opt(inode->i_sb, POSIX_ACL))
 143                 return NULL;
 144
 145         acl = get_cached_acl(inode, type);
 146         if (acl != ACL_NOT_CACHED)
 147                 return acl;
 148
 149         switch (type) {
 150         case ACL_TYPE_ACCESS:
 151                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 152                 break;
 153         case ACL_TYPE_DEFAULT:
 154                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 155                 break;
 156         default:
 157                 BUG();
 158         }
 159
 160         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 161         if (retval > 0) {
 162                 value = kmalloc(retval, GFP_NOFS);
 163                 if (!value)
 164                         return ERR_PTR(-ENOMEM);
 165                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 166         }
 167         if (retval > 0)
 168                 acl = ext3_acl_from_disk(value, retval);
 169         else if (retval == -ENODATA || retval == -ENOSYS)
 170                 acl = NULL;
 171         else
 172                 acl = ERR_PTR(retval);
 173         kfree(value);
 174
 175         if (!IS_ERR(acl))
 176                 set_cached_acl(inode, type, acl);
 177
 178         return acl;
 179 }
 180
 181 /*
 182  * Set the access or default ACL of an inode.
 183  *
 184  * inode->i_mutex: down unless called from ext3_new_inode
 185  */
 186 static int
 187 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 188              struct posix_acl *acl)
 189 {
 190         int name_index;
 191         void *value = NULL;
 192         size_t size = 0;
 193         int error;
 194
 195         if (S_ISLNK(inode->i_mode))
 196                 return -EOPNOTSUPP;
 197
 198         switch(type) {
 199                 case ACL_TYPE_ACCESS:
 200                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 201                         if (acl) {
 202                                 mode_t mode = inode->i_mode;
 203                                 error = posix_acl_equiv_mode(acl, &mode);
 204                                 if (error < 0)
 205                                         return error;
 206                                 else {
 207                                         inode->i_mode = mode;
 208                                         inode->i_ctime = CURRENT_TIME_SEC;
 209                                         ext3_mark_inode_dirty(handle, inode);
 210                                         if (error == 0)
 211                                                 acl = NULL;
 212                                 }
 213                         }
 214                         break;
 215
 216                 case ACL_TYPE_DEFAULT:
 217                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 218                         if (!S_ISDIR(inode->i_mode))
 219                                 return acl ? -EACCES : 0;
 220                         break;
 221
 222                 default:
 223                         return -EINVAL;
 224         }
 225         if (acl) {
 226                 value = ext3_acl_to_disk(acl, &size);
 227                 if (IS_ERR(value))
 228                         return (int)PTR_ERR(value);
 229         }
 230
 231         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 232                                       value, size, 0);
 233
 234         kfree(value);
 235
 236         if (!error)
 237                 set_cached_acl(inode, type, acl);
 238
 239         return error;
 240 }
 241
 242 int
 243 ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
 244 {
 245         struct posix_acl *acl;
 246
 247         if (flags & IPERM_FLAG_RCU) {
 248                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 249                         return -ECHILD;
 250                 return -EAGAIN;
 251         }
 252
 253         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 254         if (IS_ERR(acl))
 255                 return PTR_ERR(acl);
 256         if (acl) {
 257                 int error = posix_acl_permission(inode, acl, mask);
 258                 posix_acl_release(acl);
 259                 return error;
 260         }
 261
 262         return -EAGAIN;
 263 }
 264
 265 /*
 266  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 267  *
 268  * dir->i_mutex: down
 269  * inode->i_mutex: up (access to inode is still exclusive)
 270  */
 271 int
 272 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 273 {
 274         struct posix_acl *acl = NULL;
 275         int error = 0;
 276
 277         if (!S_ISLNK(inode->i_mode)) {
 278                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 279                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 280                         if (IS_ERR(acl))
 281                                 return PTR_ERR(acl);
 282                 }
 283                 if (!acl)
 284                         inode->i_mode &= ~current_umask();
 285         }
 286         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 287                 struct posix_acl *clone;
 288                 mode_t mode;
 289
 290                 if (S_ISDIR(inode->i_mode)) {
 291                         error = ext3_set_acl(handle, inode,
 292                                              ACL_TYPE_DEFAULT, acl);
 293                         if (error)
 294                                 goto cleanup;
 295                 }
 296                 clone = posix_acl_clone(acl, GFP_NOFS);
 297                 error = -ENOMEM;
 298                 if (!clone)
 299                         goto cleanup;
 300
 301                 mode = inode->i_mode;
 302                 error = posix_acl_create_masq(clone, &mode);
 303                 if (error >= 0) {
 304                         inode->i_mode = mode;
 305                         if (error > 0) {
 306                                 /* This is an extended ACL */
 307                                 error = ext3_set_acl(handle, inode,
 308                                                      ACL_TYPE_ACCESS, clone);
 309                         }
 310                 }
 311                 posix_acl_release(clone);
 312         }
 313 cleanup:
 314         posix_acl_release(acl);
 315         return error;
 316 }
 317
 318 /*
 319  * Does chmod for an inode that may have an Access Control List. The
 320  * inode->i_mode field must be updated to the desired value by the caller
 321  * before calling this function.
 322  * Returns 0 on success, or a negative error number.
 323  *
 324  * We change the ACL rather than storing some ACL entries in the file
 325  * mode permission bits (which would be more efficient), because that
 326  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 327  * for directories) are added. There are no more bits available in the
 328  * file mode.
 329  *
 330  * inode->i_mutex: down
 331  */
 332 int
 333 ext3_acl_chmod(struct inode *inode)
 334 {
 335         struct posix_acl *acl, *clone;
 336         int error;
 337
 338         if (S_ISLNK(inode->i_mode))
 339                 return -EOPNOTSUPP;
 340         if (!test_opt(inode->i_sb, POSIX_ACL))
 341                 return 0;
 342         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 343         if (IS_ERR(acl) || !acl)
 344                 return PTR_ERR(acl);
 345         clone = posix_acl_clone(acl, GFP_KERNEL);
 346         posix_acl_release(acl);
 347         if (!clone)
 348                 return -ENOMEM;
 349         error = posix_acl_chmod_masq(clone, inode->i_mode);
 350         if (!error) {
 351                 handle_t *handle;
 352                 int retries = 0;
 353
 354         retry:
 355                 handle = ext3_journal_start(inode,
 356                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 357                 if (IS_ERR(handle)) {
 358                         error = PTR_ERR(handle);
 359                         ext3_std_error(inode->i_sb, error);
 360                         goto out;
 361                 }
 362                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 363                 ext3_journal_stop(handle);
 364                 if (error == -ENOSPC &&
 365                     ext3_should_retry_alloc(inode->i_sb, &retries))
 366                         goto retry;
 367         }
 368 out:
 369         posix_acl_release(clone);
 370         return error;
 371 }
 372
 373 /*
 374  * Extended attribute handlers
 375  */
 376 static size_t
 377 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 378                            const char *name, size_t name_len, int type)
 379 {
 380         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 381
 382         if (!test_opt(dentry->d_sb, POSIX_ACL))
 383                 return 0;
 384         if (list && size <= list_len)
 385                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 386         return size;
 387 }
 388
 389 static size_t
 390 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 391                             const char *name, size_t name_len, int type)
 392 {
 393         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 394
 395         if (!test_opt(dentry->d_sb, POSIX_ACL))
 396                 return 0;
 397         if (list && size <= list_len)
 398                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 399         return size;
 400 }
 401
 402 static int
 403 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 404                    size_t size, int type)
 405 {
 406         struct posix_acl *acl;
 407         int error;
 408
 409         if (strcmp(name, "") != 0)
 410                 return -EINVAL;
 411         if (!test_opt(dentry->d_sb, POSIX_ACL))
 412                 return -EOPNOTSUPP;
 413
 414         acl = ext3_get_acl(dentry->d_inode, type);
 415         if (IS_ERR(acl))
 416                 return PTR_ERR(acl);
 417         if (acl == NULL)
 418                 return -ENODATA;
 419         error = posix_acl_to_xattr(acl, buffer, size);
 420         posix_acl_release(acl);
 421
 422         return error;
 423 }
 424
 425 static int
 426 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 427                    size_t size, int flags, int type)
 428 {
 429         struct inode *inode = dentry->d_inode;
 430         handle_t *handle;
 431         struct posix_acl *acl;
 432         int error, retries = 0;
 433
 434         if (strcmp(name, "") != 0)
 435                 return -EINVAL;
 436         if (!test_opt(inode->i_sb, POSIX_ACL))
 437                 return -EOPNOTSUPP;
 438         if (!is_owner_or_cap(inode))
 439                 return -EPERM;
 440
 441         if (value) {
 442                 acl = posix_acl_from_xattr(value, size);
 443                 if (IS_ERR(acl))
 444                         return PTR_ERR(acl);
 445                 else if (acl) {
 446                         error = posix_acl_valid(acl);
 447                         if (error)
 448                                 goto release_and_out;
 449                 }
 450         } else
 451                 acl = NULL;
 452
 453 retry:
 454         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 455         if (IS_ERR(handle))
 456                 return PTR_ERR(handle);
 457         error = ext3_set_acl(handle, inode, type, acl);
 458         ext3_journal_stop(handle);
 459         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 460                 goto retry;
 461
 462 release_and_out:
 463         posix_acl_release(acl);
 464         return error;
 465 }
 466
 467 const struct xattr_handler ext3_xattr_acl_access_handler = {
 468         .prefix = POSIX_ACL_XATTR_ACCESS,
 469         .flags  = ACL_TYPE_ACCESS,
 470         .list   = ext3_xattr_list_acl_access,
 471         .get    = ext3_xattr_get_acl,
 472         .set    = ext3_xattr_set_acl,
 473 };
 474
 475 const struct xattr_handler ext3_xattr_acl_default_handler = {
 476         .prefix = POSIX_ACL_XATTR_DEFAULT,
 477         .flags  = ACL_TYPE_DEFAULT,
 478         .list   = ext3_xattr_list_acl_default,
 479         .get    = ext3_xattr_get_acl,
 480         .set    = ext3_xattr_set_acl,
 481 };