fs/ext4/acl.c

   1 /*
   2  * linux/fs/ext4/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 "ext4_jbd2.h"
  13 #include "ext4.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 ext4_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(ext4_acl_header))
  30                  return ERR_PTR(-EINVAL);
  31         if (((ext4_acl_header *)value)->a_version !=
  32             cpu_to_le32(EXT4_ACL_VERSION))
  33                 return ERR_PTR(-EINVAL);
  34         value = (char *)value + sizeof(ext4_acl_header);
  35         count = ext4_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                 ext4_acl_entry *entry =
  45                         (ext4_acl_entry *)value;
  46                 if ((char *)value + sizeof(ext4_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
  51                 switch (acl->a_entries[n].e_tag) {
  52                 case ACL_USER_OBJ:
  53                 case ACL_GROUP_OBJ:
  54                 case ACL_MASK:
  55                 case ACL_OTHER:
  56                         value = (char *)value +
  57                                 sizeof(ext4_acl_entry_short);
  58                         acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  59                         break;
  60
  61                 case ACL_USER:
  62                 case ACL_GROUP:
  63                         value = (char *)value + sizeof(ext4_acl_entry);
  64                         if ((char *)value > end)
  65                                 goto fail;
  66                         acl->a_entries[n].e_id =
  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 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  88 {
  89         ext4_acl_header *ext_acl;
  90         char *e;
  91         size_t n;
  92
  93         *size = ext4_acl_size(acl->a_count);
  94         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
  95                         sizeof(ext4_acl_entry), GFP_NOFS);
  96         if (!ext_acl)
  97                 return ERR_PTR(-ENOMEM);
  98         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
  99         e = (char *)ext_acl + sizeof(ext4_acl_header);
 100         for (n = 0; n < acl->a_count; n++) {
 101                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
 102                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 103                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 104                 switch (acl->a_entries[n].e_tag) {
 105                 case ACL_USER:
 106                 case ACL_GROUP:
 107                         entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
 108                         e += sizeof(ext4_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(ext4_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 static inline struct posix_acl *
 130 ext4_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 131 {
 132         struct posix_acl *acl = ACCESS_ONCE(*i_acl);
 133
 134         if (acl) {
 135                 spin_lock(&inode->i_lock);
 136                 acl = *i_acl;
 137                 if (acl != EXT4_ACL_NOT_CACHED)
 138                         acl = posix_acl_dup(acl);
 139                 spin_unlock(&inode->i_lock);
 140         }
 141
 142         return acl;
 143 }
 144
 145 static inline void
 146 ext4_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 147                 struct posix_acl *acl)
 148 {
 149         spin_lock(&inode->i_lock);
 150         if (*i_acl != EXT4_ACL_NOT_CACHED)
 151                 posix_acl_release(*i_acl);
 152         *i_acl = posix_acl_dup(acl);
 153         spin_unlock(&inode->i_lock);
 154 }
 155
 156 /*
 157  * Inode operation get_posix_acl().
 158  *
 159  * inode->i_mutex: don't care
 160  */
 161 static struct posix_acl *
 162 ext4_get_acl(struct inode *inode, int type)
 163 {
 164         struct ext4_inode_info *ei = EXT4_I(inode);
 165         int name_index;
 166         char *value = NULL;
 167         struct posix_acl *acl;
 168         int retval;
 169
 170         if (!test_opt(inode->i_sb, POSIX_ACL))
 171                 return NULL;
 172
 173         switch (type) {
 174         case ACL_TYPE_ACCESS:
 175                 acl = ext4_iget_acl(inode, &ei->i_acl);
 176                 if (acl != EXT4_ACL_NOT_CACHED)
 177                         return acl;
 178                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 179                 break;
 180
 181         case ACL_TYPE_DEFAULT:
 182                 acl = ext4_iget_acl(inode, &ei->i_default_acl);
 183                 if (acl != EXT4_ACL_NOT_CACHED)
 184                         return acl;
 185                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 186                 break;
 187
 188         default:
 189                 return ERR_PTR(-EINVAL);
 190         }
 191         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 192         if (retval > 0) {
 193                 value = kmalloc(retval, GFP_NOFS);
 194                 if (!value)
 195                         return ERR_PTR(-ENOMEM);
 196                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 197         }
 198         if (retval > 0)
 199                 acl = ext4_acl_from_disk(value, retval);
 200         else if (retval == -ENODATA || retval == -ENOSYS)
 201                 acl = NULL;
 202         else
 203                 acl = ERR_PTR(retval);
 204         kfree(value);
 205
 206         if (!IS_ERR(acl)) {
 207                 switch (type) {
 208                 case ACL_TYPE_ACCESS:
 209                         ext4_iset_acl(inode, &ei->i_acl, acl);
 210                         break;
 211
 212                 case ACL_TYPE_DEFAULT:
 213                         ext4_iset_acl(inode, &ei->i_default_acl, acl);
 214                         break;
 215                 }
 216         }
 217         return acl;
 218 }
 219
 220 /*
 221  * Set the access or default ACL of an inode.
 222  *
 223  * inode->i_mutex: down unless called from ext4_new_inode
 224  */
 225 static int
 226 ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 227              struct posix_acl *acl)
 228 {
 229         struct ext4_inode_info *ei = EXT4_I(inode);
 230         int name_index;
 231         void *value = NULL;
 232         size_t size = 0;
 233         int error;
 234
 235         if (S_ISLNK(inode->i_mode))
 236                 return -EOPNOTSUPP;
 237
 238         switch (type) {
 239         case ACL_TYPE_ACCESS:
 240                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 241                 if (acl) {
 242                         mode_t mode = inode->i_mode;
 243                         error = posix_acl_equiv_mode(acl, &mode);
 244                         if (error < 0)
 245                                 return error;
 246                         else {
 247                                 inode->i_mode = mode;
 248                                 ext4_mark_inode_dirty(handle, inode);
 249                                 if (error == 0)
 250                                         acl = NULL;
 251                         }
 252                 }
 253                 break;
 254
 255         case ACL_TYPE_DEFAULT:
 256                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 257                 if (!S_ISDIR(inode->i_mode))
 258                         return acl ? -EACCES : 0;
 259                 break;
 260
 261         default:
 262                 return -EINVAL;
 263         }
 264         if (acl) {
 265                 value = ext4_acl_to_disk(acl, &size);
 266                 if (IS_ERR(value))
 267                         return (int)PTR_ERR(value);
 268         }
 269
 270         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 271                                       value, size, 0);
 272
 273         kfree(value);
 274         if (!error) {
 275                 switch (type) {
 276                 case ACL_TYPE_ACCESS:
 277                         ext4_iset_acl(inode, &ei->i_acl, acl);
 278                         break;
 279
 280                 case ACL_TYPE_DEFAULT:
 281                         ext4_iset_acl(inode, &ei->i_default_acl, acl);
 282                         break;
 283                 }
 284         }
 285         return error;
 286 }
 287
 288 static int
 289 ext4_check_acl(struct inode *inode, int mask)
 290 {
 291         struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
 292
 293         if (IS_ERR(acl))
 294                 return PTR_ERR(acl);
 295         if (acl) {
 296                 int error = posix_acl_permission(inode, acl, mask);
 297                 posix_acl_release(acl);
 298                 return error;
 299         }
 300
 301         return -EAGAIN;
 302 }
 303
 304 int
 305 ext4_permission(struct inode *inode, int mask)
 306 {
 307         return generic_permission(inode, mask, ext4_check_acl);
 308 }
 309
 310 /*
 311  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 312  *
 313  * dir->i_mutex: down
 314  * inode->i_mutex: up (access to inode is still exclusive)
 315  */
 316 int
 317 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 318 {
 319         struct posix_acl *acl = NULL;
 320         int error = 0;
 321
 322         if (!S_ISLNK(inode->i_mode)) {
 323                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 324                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
 325                         if (IS_ERR(acl))
 326                                 return PTR_ERR(acl);
 327                 }
 328                 if (!acl)
 329                         inode->i_mode &= ~current_umask();
 330         }
 331         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 332                 struct posix_acl *clone;
 333                 mode_t mode;
 334
 335                 if (S_ISDIR(inode->i_mode)) {
 336                         error = ext4_set_acl(handle, inode,
 337                                              ACL_TYPE_DEFAULT, acl);
 338                         if (error)
 339                                 goto cleanup;
 340                 }
 341                 clone = posix_acl_clone(acl, GFP_NOFS);
 342                 error = -ENOMEM;
 343                 if (!clone)
 344                         goto cleanup;
 345
 346                 mode = inode->i_mode;
 347                 error = posix_acl_create_masq(clone, &mode);
 348                 if (error >= 0) {
 349                         inode->i_mode = mode;
 350                         if (error > 0) {
 351                                 /* This is an extended ACL */
 352                                 error = ext4_set_acl(handle, inode,
 353                                                      ACL_TYPE_ACCESS, clone);
 354                         }
 355                 }
 356                 posix_acl_release(clone);
 357         }
 358 cleanup:
 359         posix_acl_release(acl);
 360         return error;
 361 }
 362
 363 /*
 364  * Does chmod for an inode that may have an Access Control List. The
 365  * inode->i_mode field must be updated to the desired value by the caller
 366  * before calling this function.
 367  * Returns 0 on success, or a negative error number.
 368  *
 369  * We change the ACL rather than storing some ACL entries in the file
 370  * mode permission bits (which would be more efficient), because that
 371  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 372  * for directories) are added. There are no more bits available in the
 373  * file mode.
 374  *
 375  * inode->i_mutex: down
 376  */
 377 int
 378 ext4_acl_chmod(struct inode *inode)
 379 {
 380         struct posix_acl *acl, *clone;
 381         int error;
 382
 383         if (S_ISLNK(inode->i_mode))
 384                 return -EOPNOTSUPP;
 385         if (!test_opt(inode->i_sb, POSIX_ACL))
 386                 return 0;
 387         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
 388         if (IS_ERR(acl) || !acl)
 389                 return PTR_ERR(acl);
 390         clone = posix_acl_clone(acl, GFP_KERNEL);
 391         posix_acl_release(acl);
 392         if (!clone)
 393                 return -ENOMEM;
 394         error = posix_acl_chmod_masq(clone, inode->i_mode);
 395         if (!error) {
 396                 handle_t *handle;
 397                 int retries = 0;
 398
 399         retry:
 400                 handle = ext4_journal_start(inode,
 401                                 EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
 402                 if (IS_ERR(handle)) {
 403                         error = PTR_ERR(handle);
 404                         ext4_std_error(inode->i_sb, error);
 405                         goto out;
 406                 }
 407                 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 408                 ext4_journal_stop(handle);
 409                 if (error == -ENOSPC &&
 410                     ext4_should_retry_alloc(inode->i_sb, &retries))
 411                         goto retry;
 412         }
 413 out:
 414         posix_acl_release(clone);
 415         return error;
 416 }
 417
 418 /*
 419  * Extended attribute handlers
 420  */
 421 static size_t
 422 ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
 423                            const char *name, size_t name_len)
 424 {
 425         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 426
 427         if (!test_opt(inode->i_sb, POSIX_ACL))
 428                 return 0;
 429         if (list && size <= list_len)
 430                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 431         return size;
 432 }
 433
 434 static size_t
 435 ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
 436                             const char *name, size_t name_len)
 437 {
 438         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 439
 440         if (!test_opt(inode->i_sb, POSIX_ACL))
 441                 return 0;
 442         if (list && size <= list_len)
 443                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 444         return size;
 445 }
 446
 447 static int
 448 ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 449 {
 450         struct posix_acl *acl;
 451         int error;
 452
 453         if (!test_opt(inode->i_sb, POSIX_ACL))
 454                 return -EOPNOTSUPP;
 455
 456         acl = ext4_get_acl(inode, type);
 457         if (IS_ERR(acl))
 458                 return PTR_ERR(acl);
 459         if (acl == NULL)
 460                 return -ENODATA;
 461         error = posix_acl_to_xattr(acl, buffer, size);
 462         posix_acl_release(acl);
 463
 464         return error;
 465 }
 466
 467 static int
 468 ext4_xattr_get_acl_access(struct inode *inode, const char *name,
 469                           void *buffer, size_t size)
 470 {
 471         if (strcmp(name, "") != 0)
 472                 return -EINVAL;
 473         return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 474 }
 475
 476 static int
 477 ext4_xattr_get_acl_default(struct inode *inode, const char *name,
 478                            void *buffer, size_t size)
 479 {
 480         if (strcmp(name, "") != 0)
 481                 return -EINVAL;
 482         return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 483 }
 484
 485 static int
 486 ext4_xattr_set_acl(struct inode *inode, int type, const void *value,
 487                    size_t size)
 488 {
 489         handle_t *handle;
 490         struct posix_acl *acl;
 491         int error, retries = 0;
 492
 493         if (!test_opt(inode->i_sb, POSIX_ACL))
 494                 return -EOPNOTSUPP;
 495         if (!is_owner_or_cap(inode))
 496                 return -EPERM;
 497
 498         if (value) {
 499                 acl = posix_acl_from_xattr(value, size);
 500                 if (IS_ERR(acl))
 501                         return PTR_ERR(acl);
 502                 else if (acl) {
 503                         error = posix_acl_valid(acl);
 504                         if (error)
 505                                 goto release_and_out;
 506                 }
 507         } else
 508                 acl = NULL;
 509
 510 retry:
 511         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
 512         if (IS_ERR(handle))
 513                 return PTR_ERR(handle);
 514         error = ext4_set_acl(handle, inode, type, acl);
 515         ext4_journal_stop(handle);
 516         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 517                 goto retry;
 518
 519 release_and_out:
 520         posix_acl_release(acl);
 521         return error;
 522 }
 523
 524 static int
 525 ext4_xattr_set_acl_access(struct inode *inode, const char *name,
 526                           const void *value, size_t size, int flags)
 527 {
 528         if (strcmp(name, "") != 0)
 529                 return -EINVAL;
 530         return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 531 }
 532
 533 static int
 534 ext4_xattr_set_acl_default(struct inode *inode, const char *name,
 535                            const void *value, size_t size, int flags)
 536 {
 537         if (strcmp(name, "") != 0)
 538                 return -EINVAL;
 539         return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 540 }
 541
 542 struct xattr_handler ext4_xattr_acl_access_handler = {
 543         .prefix = POSIX_ACL_XATTR_ACCESS,
 544         .list   = ext4_xattr_list_acl_access,
 545         .get    = ext4_xattr_get_acl_access,
 546         .set    = ext4_xattr_set_acl_access,
 547 };
 548
 549 struct xattr_handler ext4_xattr_acl_default_handler = {
 550         .prefix = POSIX_ACL_XATTR_DEFAULT,
 551         .list   = ext4_xattr_list_acl_default,
 552         .get    = ext4_xattr_get_acl_default,
 553         .set    = ext4_xattr_set_acl_default,
 554 };