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 <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)
 244 {
 245         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 246
 247         if (IS_ERR(acl))
 248                 return PTR_ERR(acl);
 249         if (acl) {
 250                 int error = posix_acl_permission(inode, acl, mask);
 251                 posix_acl_release(acl);
 252                 return error;
 253         }
 254
 255         return -EAGAIN;
 256 }
 257
 258 /*
 259  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 260  *
 261  * dir->i_mutex: down
 262  * inode->i_mutex: up (access to inode is still exclusive)
 263  */
 264 int
 265 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 266 {
 267         struct posix_acl *acl = NULL;
 268         int error = 0;
 269
 270         if (!S_ISLNK(inode->i_mode)) {
 271                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 272                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 273                         if (IS_ERR(acl))
 274                                 return PTR_ERR(acl);
 275                 }
 276                 if (!acl)
 277                         inode->i_mode &= ~current_umask();
 278         }
 279         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 280                 struct posix_acl *clone;
 281                 mode_t mode;
 282
 283                 if (S_ISDIR(inode->i_mode)) {
 284                         error = ext3_set_acl(handle, inode,
 285                                              ACL_TYPE_DEFAULT, acl);
 286                         if (error)
 287                                 goto cleanup;
 288                 }
 289                 clone = posix_acl_clone(acl, GFP_NOFS);
 290                 error = -ENOMEM;
 291                 if (!clone)
 292                         goto cleanup;
 293
 294                 mode = inode->i_mode;
 295                 error = posix_acl_create_masq(clone, &mode);
 296                 if (error >= 0) {
 297                         inode->i_mode = mode;
 298                         if (error > 0) {
 299                                 /* This is an extended ACL */
 300                                 error = ext3_set_acl(handle, inode,
 301                                                      ACL_TYPE_ACCESS, clone);
 302                         }
 303                 }
 304                 posix_acl_release(clone);
 305         }
 306 cleanup:
 307         posix_acl_release(acl);
 308         return error;
 309 }
 310
 311 /*
 312  * Does chmod for an inode that may have an Access Control List. The
 313  * inode->i_mode field must be updated to the desired value by the caller
 314  * before calling this function.
 315  * Returns 0 on success, or a negative error number.
 316  *
 317  * We change the ACL rather than storing some ACL entries in the file
 318  * mode permission bits (which would be more efficient), because that
 319  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 320  * for directories) are added. There are no more bits available in the
 321  * file mode.
 322  *
 323  * inode->i_mutex: down
 324  */
 325 int
 326 ext3_acl_chmod(struct inode *inode)
 327 {
 328         struct posix_acl *acl, *clone;
 329         int error;
 330
 331         if (S_ISLNK(inode->i_mode))
 332                 return -EOPNOTSUPP;
 333         if (!test_opt(inode->i_sb, POSIX_ACL))
 334                 return 0;
 335         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 336         if (IS_ERR(acl) || !acl)
 337                 return PTR_ERR(acl);
 338         clone = posix_acl_clone(acl, GFP_KERNEL);
 339         posix_acl_release(acl);
 340         if (!clone)
 341                 return -ENOMEM;
 342         error = posix_acl_chmod_masq(clone, inode->i_mode);
 343         if (!error) {
 344                 handle_t *handle;
 345                 int retries = 0;
 346
 347         retry:
 348                 handle = ext3_journal_start(inode,
 349                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 350                 if (IS_ERR(handle)) {
 351                         error = PTR_ERR(handle);
 352                         ext3_std_error(inode->i_sb, error);
 353                         goto out;
 354                 }
 355                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 356                 ext3_journal_stop(handle);
 357                 if (error == -ENOSPC &&
 358                     ext3_should_retry_alloc(inode->i_sb, &retries))
 359                         goto retry;
 360         }
 361 out:
 362         posix_acl_release(clone);
 363         return error;
 364 }
 365
 366 /*
 367  * Extended attribute handlers
 368  */
 369 static size_t
 370 ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 371                            const char *name, size_t name_len, int type)
 372 {
 373         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 374
 375         if (!test_opt(dentry->d_sb, POSIX_ACL))
 376                 return 0;
 377         if (list && size <= list_len)
 378                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 379         return size;
 380 }
 381
 382 static size_t
 383 ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 384                             const char *name, size_t name_len, int type)
 385 {
 386         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 387
 388         if (!test_opt(dentry->d_sb, POSIX_ACL))
 389                 return 0;
 390         if (list && size <= list_len)
 391                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 392         return size;
 393 }
 394
 395 static int
 396 ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 397                    size_t size, int type)
 398 {
 399         struct posix_acl *acl;
 400         int error;
 401
 402         if (strcmp(name, "") != 0)
 403                 return -EINVAL;
 404         if (!test_opt(dentry->d_sb, POSIX_ACL))
 405                 return -EOPNOTSUPP;
 406
 407         acl = ext3_get_acl(dentry->d_inode, type);
 408         if (IS_ERR(acl))
 409                 return PTR_ERR(acl);
 410         if (acl == NULL)
 411                 return -ENODATA;
 412         error = posix_acl_to_xattr(acl, buffer, size);
 413         posix_acl_release(acl);
 414
 415         return error;
 416 }
 417
 418 static int
 419 ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 420                    size_t size, int flags, int type)
 421 {
 422         struct inode *inode = dentry->d_inode;
 423         handle_t *handle;
 424         struct posix_acl *acl;
 425         int error, retries = 0;
 426
 427         if (strcmp(name, "") != 0)
 428                 return -EINVAL;
 429         if (!test_opt(inode->i_sb, POSIX_ACL))
 430                 return -EOPNOTSUPP;
 431         if (!is_owner_or_cap(inode))
 432                 return -EPERM;
 433
 434         if (value) {
 435                 acl = posix_acl_from_xattr(value, size);
 436                 if (IS_ERR(acl))
 437                         return PTR_ERR(acl);
 438                 else if (acl) {
 439                         error = posix_acl_valid(acl);
 440                         if (error)
 441                                 goto release_and_out;
 442                 }
 443         } else
 444                 acl = NULL;
 445
 446 retry:
 447         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 448         if (IS_ERR(handle))
 449                 return PTR_ERR(handle);
 450         error = ext3_set_acl(handle, inode, type, acl);
 451         ext3_journal_stop(handle);
 452         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 453                 goto retry;
 454
 455 release_and_out:
 456         posix_acl_release(acl);
 457         return error;
 458 }
 459
 460 const struct xattr_handler ext3_xattr_acl_access_handler = {
 461         .prefix = POSIX_ACL_XATTR_ACCESS,
 462         .flags  = ACL_TYPE_ACCESS,
 463         .list   = ext3_xattr_list_acl_access,
 464         .get    = ext3_xattr_get_acl,
 465         .set    = ext3_xattr_set_acl,
 466 };
 467
 468 const struct xattr_handler ext3_xattr_acl_default_handler = {
 469         .prefix = POSIX_ACL_XATTR_DEFAULT,
 470         .flags  = ACL_TYPE_DEFAULT,
 471         .list   = ext3_xattr_list_acl_default,
 472         .get    = ext3_xattr_get_acl,
 473         .set    = ext3_xattr_set_acl,
 474 };