fs/ext2/acl.c

   1 /*
   2  * linux/fs/ext2/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  */
   6
   7 #include <linux/capability.h>
   8 #include <linux/init.h>
   9 #include <linux/sched.h>
  10 #include <linux/slab.h>
  11 #include <linux/fs.h>
  12 #include "ext2.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 ext2_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(ext2_acl_header))
  29                  return ERR_PTR(-EINVAL);
  30         if (((ext2_acl_header *)value)->a_version !=
  31             cpu_to_le32(EXT2_ACL_VERSION))
  32                 return ERR_PTR(-EINVAL);
  33         value = (char *)value + sizeof(ext2_acl_header);
  34         count = ext2_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                 ext2_acl_entry *entry =
  44                         (ext2_acl_entry *)value;
  45                 if ((char *)value + sizeof(ext2_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(ext2_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(ext2_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 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  86 {
  87         ext2_acl_header *ext_acl;
  88         char *e;
  89         size_t n;
  90
  91         *size = ext2_acl_size(acl->a_count);
  92         ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
  93                         sizeof(ext2_acl_entry), GFP_KERNEL);
  94         if (!ext_acl)
  95                 return ERR_PTR(-ENOMEM);
  96         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
  97         e = (char *)ext_acl + sizeof(ext2_acl_header);
  98         for (n=0; n < acl->a_count; n++) {
  99                 ext2_acl_entry *entry = (ext2_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(ext2_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(ext2_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 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 130 {
 131         struct posix_acl *acl = ACL_NOT_CACHED;
 132
 133         spin_lock(&inode->i_lock);
 134         if (*i_acl != 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 ext2_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 != 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->i_mutex: don't care
 154  */
 155 static struct posix_acl *
 156 ext2_get_acl(struct inode *inode, int type)
 157 {
 158         int name_index;
 159         char *value = NULL;
 160         struct posix_acl *acl;
 161         int retval;
 162
 163         if (!test_opt(inode->i_sb, POSIX_ACL))
 164                 return NULL;
 165
 166         switch(type) {
 167                 case ACL_TYPE_ACCESS:
 168                         acl = ext2_iget_acl(inode, &inode->i_acl);
 169                         if (acl != ACL_NOT_CACHED)
 170                                 return acl;
 171                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 172                         break;
 173
 174                 case ACL_TYPE_DEFAULT:
 175                         acl = ext2_iget_acl(inode, &inode->i_default_acl);
 176                         if (acl != ACL_NOT_CACHED)
 177                                 return acl;
 178                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 179                         break;
 180
 181                 default:
 182                         return ERR_PTR(-EINVAL);
 183         }
 184         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 185         if (retval > 0) {
 186                 value = kmalloc(retval, GFP_KERNEL);
 187                 if (!value)
 188                         return ERR_PTR(-ENOMEM);
 189                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 190         }
 191         if (retval > 0)
 192                 acl = ext2_acl_from_disk(value, retval);
 193         else if (retval == -ENODATA || retval == -ENOSYS)
 194                 acl = NULL;
 195         else
 196                 acl = ERR_PTR(retval);
 197         kfree(value);
 198
 199         if (!IS_ERR(acl)) {
 200                 switch(type) {
 201                         case ACL_TYPE_ACCESS:
 202                                 ext2_iset_acl(inode, &inode->i_acl, acl);
 203                                 break;
 204
 205                         case ACL_TYPE_DEFAULT:
 206                                 ext2_iset_acl(inode, &inode->i_default_acl, acl);
 207                                 break;
 208                 }
 209         }
 210         return acl;
 211 }
 212
 213 /*
 214  * inode->i_mutex: down
 215  */
 216 static int
 217 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 218 {
 219         int name_index;
 220         void *value = NULL;
 221         size_t size = 0;
 222         int error;
 223
 224         if (S_ISLNK(inode->i_mode))
 225                 return -EOPNOTSUPP;
 226         if (!test_opt(inode->i_sb, POSIX_ACL))
 227                 return 0;
 228
 229         switch(type) {
 230                 case ACL_TYPE_ACCESS:
 231                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 232                         if (acl) {
 233                                 mode_t mode = inode->i_mode;
 234                                 error = posix_acl_equiv_mode(acl, &mode);
 235                                 if (error < 0)
 236                                         return error;
 237                                 else {
 238                                         inode->i_mode = mode;
 239                                         mark_inode_dirty(inode);
 240                                         if (error == 0)
 241                                                 acl = NULL;
 242                                 }
 243                         }
 244                         break;
 245
 246                 case ACL_TYPE_DEFAULT:
 247                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 248                         if (!S_ISDIR(inode->i_mode))
 249                                 return acl ? -EACCES : 0;
 250                         break;
 251
 252                 default:
 253                         return -EINVAL;
 254         }
 255         if (acl) {
 256                 value = ext2_acl_to_disk(acl, &size);
 257                 if (IS_ERR(value))
 258                         return (int)PTR_ERR(value);
 259         }
 260
 261         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 262
 263         kfree(value);
 264         if (!error) {
 265                 switch(type) {
 266                         case ACL_TYPE_ACCESS:
 267                                 ext2_iset_acl(inode, &inode->i_acl, acl);
 268                                 break;
 269
 270                         case ACL_TYPE_DEFAULT:
 271                                 ext2_iset_acl(inode, &inode->i_default_acl, acl);
 272                                 break;
 273                 }
 274         }
 275         return error;
 276 }
 277
 278 static int
 279 ext2_check_acl(struct inode *inode, int mask)
 280 {
 281         struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 282
 283         if (IS_ERR(acl))
 284                 return PTR_ERR(acl);
 285         if (acl) {
 286                 int error = posix_acl_permission(inode, acl, mask);
 287                 posix_acl_release(acl);
 288                 return error;
 289         }
 290
 291         return -EAGAIN;
 292 }
 293
 294 int
 295 ext2_permission(struct inode *inode, int mask)
 296 {
 297         return generic_permission(inode, mask, ext2_check_acl);
 298 }
 299
 300 /*
 301  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 302  *
 303  * dir->i_mutex: down
 304  * inode->i_mutex: up (access to inode is still exclusive)
 305  */
 306 int
 307 ext2_init_acl(struct inode *inode, struct inode *dir)
 308 {
 309         struct posix_acl *acl = NULL;
 310         int error = 0;
 311
 312         if (!S_ISLNK(inode->i_mode)) {
 313                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 314                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 315                         if (IS_ERR(acl))
 316                                 return PTR_ERR(acl);
 317                 }
 318                 if (!acl)
 319                         inode->i_mode &= ~current_umask();
 320         }
 321         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 322                struct posix_acl *clone;
 323                mode_t mode;
 324
 325                 if (S_ISDIR(inode->i_mode)) {
 326                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 327                         if (error)
 328                                 goto cleanup;
 329                 }
 330                 clone = posix_acl_clone(acl, GFP_KERNEL);
 331                 error = -ENOMEM;
 332                 if (!clone)
 333                         goto cleanup;
 334                 mode = inode->i_mode;
 335                 error = posix_acl_create_masq(clone, &mode);
 336                 if (error >= 0) {
 337                         inode->i_mode = mode;
 338                         if (error > 0) {
 339                                 /* This is an extended ACL */
 340                                 error = ext2_set_acl(inode,
 341                                                      ACL_TYPE_ACCESS, clone);
 342                         }
 343                 }
 344                 posix_acl_release(clone);
 345         }
 346 cleanup:
 347        posix_acl_release(acl);
 348        return error;
 349 }
 350
 351 /*
 352  * Does chmod for an inode that may have an Access Control List. The
 353  * inode->i_mode field must be updated to the desired value by the caller
 354  * before calling this function.
 355  * Returns 0 on success, or a negative error number.
 356  *
 357  * We change the ACL rather than storing some ACL entries in the file
 358  * mode permission bits (which would be more efficient), because that
 359  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 360  * for directories) are added. There are no more bits available in the
 361  * file mode.
 362  *
 363  * inode->i_mutex: down
 364  */
 365 int
 366 ext2_acl_chmod(struct inode *inode)
 367 {
 368         struct posix_acl *acl, *clone;
 369         int error;
 370
 371         if (!test_opt(inode->i_sb, POSIX_ACL))
 372                 return 0;
 373         if (S_ISLNK(inode->i_mode))
 374                 return -EOPNOTSUPP;
 375         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 376         if (IS_ERR(acl) || !acl)
 377                 return PTR_ERR(acl);
 378         clone = posix_acl_clone(acl, GFP_KERNEL);
 379         posix_acl_release(acl);
 380         if (!clone)
 381                 return -ENOMEM;
 382         error = posix_acl_chmod_masq(clone, inode->i_mode);
 383         if (!error)
 384                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 385         posix_acl_release(clone);
 386         return error;
 387 }
 388
 389 /*
 390  * Extended attribut handlers
 391  */
 392 static size_t
 393 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
 394                            const char *name, size_t name_len)
 395 {
 396         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 397
 398         if (!test_opt(inode->i_sb, POSIX_ACL))
 399                 return 0;
 400         if (list && size <= list_size)
 401                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 402         return size;
 403 }
 404
 405 static size_t
 406 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
 407                             const char *name, size_t name_len)
 408 {
 409         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 410
 411         if (!test_opt(inode->i_sb, POSIX_ACL))
 412                 return 0;
 413         if (list && size <= list_size)
 414                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 415         return size;
 416 }
 417
 418 static int
 419 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 420 {
 421         struct posix_acl *acl;
 422         int error;
 423
 424         if (!test_opt(inode->i_sb, POSIX_ACL))
 425                 return -EOPNOTSUPP;
 426
 427         acl = ext2_get_acl(inode, type);
 428         if (IS_ERR(acl))
 429                 return PTR_ERR(acl);
 430         if (acl == NULL)
 431                 return -ENODATA;
 432         error = posix_acl_to_xattr(acl, buffer, size);
 433         posix_acl_release(acl);
 434
 435         return error;
 436 }
 437
 438 static int
 439 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
 440                           void *buffer, size_t size)
 441 {
 442         if (strcmp(name, "") != 0)
 443                 return -EINVAL;
 444         return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 445 }
 446
 447 static int
 448 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
 449                            void *buffer, size_t size)
 450 {
 451         if (strcmp(name, "") != 0)
 452                 return -EINVAL;
 453         return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 454 }
 455
 456 static int
 457 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
 458                    size_t size)
 459 {
 460         struct posix_acl *acl;
 461         int error;
 462
 463         if (!test_opt(inode->i_sb, POSIX_ACL))
 464                 return -EOPNOTSUPP;
 465         if (!is_owner_or_cap(inode))
 466                 return -EPERM;
 467
 468         if (value) {
 469                 acl = posix_acl_from_xattr(value, size);
 470                 if (IS_ERR(acl))
 471                         return PTR_ERR(acl);
 472                 else if (acl) {
 473                         error = posix_acl_valid(acl);
 474                         if (error)
 475                                 goto release_and_out;
 476                 }
 477         } else
 478                 acl = NULL;
 479
 480         error = ext2_set_acl(inode, type, acl);
 481
 482 release_and_out:
 483         posix_acl_release(acl);
 484         return error;
 485 }
 486
 487 static int
 488 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
 489                           const void *value, size_t size, int flags)
 490 {
 491         if (strcmp(name, "") != 0)
 492                 return -EINVAL;
 493         return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 494 }
 495
 496 static int
 497 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
 498                            const void *value, size_t size, int flags)
 499 {
 500         if (strcmp(name, "") != 0)
 501                 return -EINVAL;
 502         return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 503 }
 504
 505 struct xattr_handler ext2_xattr_acl_access_handler = {
 506         .prefix = POSIX_ACL_XATTR_ACCESS,
 507         .list   = ext2_xattr_list_acl_access,
 508         .get    = ext2_xattr_get_acl_access,
 509         .set    = ext2_xattr_set_acl_access,
 510 };
 511
 512 struct xattr_handler ext2_xattr_acl_default_handler = {
 513         .prefix = POSIX_ACL_XATTR_DEFAULT,
 514         .list   = ext2_xattr_list_acl_default,
 515         .get    = ext2_xattr_get_acl_default,
 516         .set    = ext2_xattr_set_acl_default,
 517 };