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