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