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   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 = EXT2_ACL_NOT_CACHED;
 132
 133         spin_lock(&inode->i_lock);
 134         if (*i_acl != EXT2_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 != EXT2_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         struct ext2_inode_info *ei = EXT2_I(inode);
 159         int name_index;
 160         char *value = NULL;
 161         struct posix_acl *acl;
 162         int retval;
 163
 164         if (!test_opt(inode->i_sb, POSIX_ACL))
 165                 return NULL;
 166
 167         switch(type) {
 168                 case ACL_TYPE_ACCESS:
 169                         acl = ext2_iget_acl(inode, &ei->i_acl);
 170                         if (acl != EXT2_ACL_NOT_CACHED)
 171                                 return acl;
 172                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 173                         break;
 174
 175                 case ACL_TYPE_DEFAULT:
 176                         acl = ext2_iget_acl(inode, &ei->i_default_acl);
 177                         if (acl != EXT2_ACL_NOT_CACHED)
 178                                 return acl;
 179                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 180                         break;
 181
 182                 default:
 183                         return ERR_PTR(-EINVAL);
 184         }
 185         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 186         if (retval > 0) {
 187                 value = kmalloc(retval, GFP_KERNEL);
 188                 if (!value)
 189                         return ERR_PTR(-ENOMEM);
 190                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 191         }
 192         if (retval > 0)
 193                 acl = ext2_acl_from_disk(value, retval);
 194         else if (retval == -ENODATA || retval == -ENOSYS)
 195                 acl = NULL;
 196         else
 197                 acl = ERR_PTR(retval);
 198         kfree(value);
 199
 200         if (!IS_ERR(acl)) {
 201                 switch(type) {
 202                         case ACL_TYPE_ACCESS:
 203                                 ext2_iset_acl(inode, &ei->i_acl, acl);
 204                                 break;
 205
 206                         case ACL_TYPE_DEFAULT:
 207                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
 208                                 break;
 209                 }
 210         }
 211         return acl;
 212 }
 213
 214 /*
 215  * inode->i_mutex: down
 216  */
 217 static int
 218 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 219 {
 220         struct ext2_inode_info *ei = EXT2_I(inode);
 221         int name_index;
 222         void *value = NULL;
 223         size_t size = 0;
 224         int error;
 225
 226         if (S_ISLNK(inode->i_mode))
 227                 return -EOPNOTSUPP;
 228         if (!test_opt(inode->i_sb, POSIX_ACL))
 229                 return 0;
 230
 231         switch(type) {
 232                 case ACL_TYPE_ACCESS:
 233                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 234                         if (acl) {
 235                                 mode_t mode = inode->i_mode;
 236                                 error = posix_acl_equiv_mode(acl, &mode);
 237                                 if (error < 0)
 238                                         return error;
 239                                 else {
 240                                         inode->i_mode = mode;
 241                                         mark_inode_dirty(inode);
 242                                         if (error == 0)
 243                                                 acl = NULL;
 244                                 }
 245                         }
 246                         break;
 247
 248                 case ACL_TYPE_DEFAULT:
 249                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 250                         if (!S_ISDIR(inode->i_mode))
 251                                 return acl ? -EACCES : 0;
 252                         break;
 253
 254                 default:
 255                         return -EINVAL;
 256         }
 257         if (acl) {
 258                 value = ext2_acl_to_disk(acl, &size);
 259                 if (IS_ERR(value))
 260                         return (int)PTR_ERR(value);
 261         }
 262
 263         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 264
 265         kfree(value);
 266         if (!error) {
 267                 switch(type) {
 268                         case ACL_TYPE_ACCESS:
 269                                 ext2_iset_acl(inode, &ei->i_acl, acl);
 270                                 break;
 271
 272                         case ACL_TYPE_DEFAULT:
 273                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
 274                                 break;
 275                 }
 276         }
 277         return error;
 278 }
 279
 280 static int
 281 ext2_check_acl(struct inode *inode, int mask)
 282 {
 283         struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 284
 285         if (IS_ERR(acl))
 286                 return PTR_ERR(acl);
 287         if (acl) {
 288                 int error = posix_acl_permission(inode, acl, mask);
 289                 posix_acl_release(acl);
 290                 return error;
 291         }
 292
 293         return -EAGAIN;
 294 }
 295
 296 int
 297 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
 298 {
 299         return generic_permission(inode, mask, ext2_check_acl);
 300 }
 301
 302 /*
 303  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 304  *
 305  * dir->i_mutex: down
 306  * inode->i_mutex: up (access to inode is still exclusive)
 307  */
 308 int
 309 ext2_init_acl(struct inode *inode, struct inode *dir)
 310 {
 311         struct posix_acl *acl = NULL;
 312         int error = 0;
 313
 314         if (!S_ISLNK(inode->i_mode)) {
 315                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 316                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 317                         if (IS_ERR(acl))
 318                                 return PTR_ERR(acl);
 319                 }
 320                 if (!acl)
 321                         inode->i_mode &= ~current->fs->umask;
 322         }
 323         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 324                struct posix_acl *clone;
 325                mode_t mode;
 326
 327                 if (S_ISDIR(inode->i_mode)) {
 328                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 329                         if (error)
 330                                 goto cleanup;
 331                 }
 332                 clone = posix_acl_clone(acl, GFP_KERNEL);
 333                 error = -ENOMEM;
 334                 if (!clone)
 335                         goto cleanup;
 336                 mode = inode->i_mode;
 337                 error = posix_acl_create_masq(clone, &mode);
 338                 if (error >= 0) {
 339                         inode->i_mode = mode;
 340                         if (error > 0) {
 341                                 /* This is an extended ACL */
 342                                 error = ext2_set_acl(inode,
 343                                                      ACL_TYPE_ACCESS, clone);
 344                         }
 345                 }
 346                 posix_acl_release(clone);
 347         }
 348 cleanup:
 349        posix_acl_release(acl);
 350        return error;
 351 }
 352
 353 /*
 354  * Does chmod for an inode that may have an Access Control List. The
 355  * inode->i_mode field must be updated to the desired value by the caller
 356  * before calling this function.
 357  * Returns 0 on success, or a negative error number.
 358  *
 359  * We change the ACL rather than storing some ACL entries in the file
 360  * mode permission bits (which would be more efficient), because that
 361  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 362  * for directories) are added. There are no more bits available in the
 363  * file mode.
 364  *
 365  * inode->i_mutex: down
 366  */
 367 int
 368 ext2_acl_chmod(struct inode *inode)
 369 {
 370         struct posix_acl *acl, *clone;
 371         int error;
 372
 373         if (!test_opt(inode->i_sb, POSIX_ACL))
 374                 return 0;
 375         if (S_ISLNK(inode->i_mode))
 376                 return -EOPNOTSUPP;
 377         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 378         if (IS_ERR(acl) || !acl)
 379                 return PTR_ERR(acl);
 380         clone = posix_acl_clone(acl, GFP_KERNEL);
 381         posix_acl_release(acl);
 382         if (!clone)
 383                 return -ENOMEM;
 384         error = posix_acl_chmod_masq(clone, inode->i_mode);
 385         if (!error)
 386                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 387         posix_acl_release(clone);
 388         return error;
 389 }
 390
 391 /*
 392  * Extended attribut handlers
 393  */
 394 static size_t
 395 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
 396                            const char *name, size_t name_len)
 397 {
 398         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 399
 400         if (!test_opt(inode->i_sb, POSIX_ACL))
 401                 return 0;
 402         if (list && size <= list_size)
 403                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 404         return size;
 405 }
 406
 407 static size_t
 408 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
 409                             const char *name, size_t name_len)
 410 {
 411         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 412
 413         if (!test_opt(inode->i_sb, POSIX_ACL))
 414                 return 0;
 415         if (list && size <= list_size)
 416                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 417         return size;
 418 }
 419
 420 static int
 421 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 422 {
 423         struct posix_acl *acl;
 424         int error;
 425
 426         if (!test_opt(inode->i_sb, POSIX_ACL))
 427                 return -EOPNOTSUPP;
 428
 429         acl = ext2_get_acl(inode, type);
 430         if (IS_ERR(acl))
 431                 return PTR_ERR(acl);
 432         if (acl == NULL)
 433                 return -ENODATA;
 434         error = posix_acl_to_xattr(acl, buffer, size);
 435         posix_acl_release(acl);
 436
 437         return error;
 438 }
 439
 440 static int
 441 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
 442                           void *buffer, size_t size)
 443 {
 444         if (strcmp(name, "") != 0)
 445                 return -EINVAL;
 446         return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 447 }
 448
 449 static int
 450 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
 451                            void *buffer, size_t size)
 452 {
 453         if (strcmp(name, "") != 0)
 454                 return -EINVAL;
 455         return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 456 }
 457
 458 static int
 459 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
 460                    size_t size)
 461 {
 462         struct posix_acl *acl;
 463         int error;
 464
 465         if (!test_opt(inode->i_sb, POSIX_ACL))
 466                 return -EOPNOTSUPP;
 467         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 468                 return -EPERM;
 469
 470         if (value) {
 471                 acl = posix_acl_from_xattr(value, size);
 472                 if (IS_ERR(acl))
 473                         return PTR_ERR(acl);
 474                 else if (acl) {
 475                         error = posix_acl_valid(acl);
 476                         if (error)
 477                                 goto release_and_out;
 478                 }
 479         } else
 480                 acl = NULL;
 481
 482         error = ext2_set_acl(inode, type, acl);
 483
 484 release_and_out:
 485         posix_acl_release(acl);
 486         return error;
 487 }
 488
 489 static int
 490 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
 491                           const void *value, size_t size, int flags)
 492 {
 493         if (strcmp(name, "") != 0)
 494                 return -EINVAL;
 495         return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 496 }
 497
 498 static int
 499 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
 500                            const void *value, size_t size, int flags)
 501 {
 502         if (strcmp(name, "") != 0)
 503                 return -EINVAL;
 504         return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 505 }
 506
 507 struct xattr_handler ext2_xattr_acl_access_handler = {
 508         .prefix = POSIX_ACL_XATTR_ACCESS,
 509         .list   = ext2_xattr_list_acl_access,
 510         .get    = ext2_xattr_get_acl_access,
 511         .set    = ext2_xattr_set_acl_access,
 512 };
 513
 514 struct xattr_handler ext2_xattr_acl_default_handler = {
 515         .prefix = POSIX_ACL_XATTR_DEFAULT,
 516         .list   = ext2_xattr_list_acl_default,
 517         .get    = ext2_xattr_get_acl_default,
 518         .set    = ext2_xattr_set_acl_default,
 519 };