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/init.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/fs.h>
  11 #include "ext2.h"
  12 #include "xattr.h"
  13 #include "acl.h"
  14
  15 /*
  16  * Convert from filesystem to in-memory representation.
  17  */
  18 static struct posix_acl *
  19 ext2_acl_from_disk(const void *value, size_t size)
  20 {
  21         const char *end = (char *)value + size;
  22         int n, count;
  23         struct posix_acl *acl;
  24
  25         if (!value)
  26                 return NULL;
  27         if (size < sizeof(ext2_acl_header))
  28                  return ERR_PTR(-EINVAL);
  29         if (((ext2_acl_header *)value)->a_version !=
  30             cpu_to_le32(EXT2_ACL_VERSION))
  31                 return ERR_PTR(-EINVAL);
  32         value = (char *)value + sizeof(ext2_acl_header);
  33         count = ext2_acl_count(size);
  34         if (count < 0)
  35                 return ERR_PTR(-EINVAL);
  36         if (count == 0)
  37                 return NULL;
  38         acl = posix_acl_alloc(count, GFP_KERNEL);
  39         if (!acl)
  40                 return ERR_PTR(-ENOMEM);
  41         for (n=0; n < count; n++) {
  42                 ext2_acl_entry *entry =
  43                         (ext2_acl_entry *)value;
  44                 if ((char *)value + sizeof(ext2_acl_entry_short) > end)
  45                         goto fail;
  46                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  47                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  48                 switch(acl->a_entries[n].e_tag) {
  49                         case ACL_USER_OBJ:
  50                         case ACL_GROUP_OBJ:
  51                         case ACL_MASK:
  52                         case ACL_OTHER:
  53                                 value = (char *)value +
  54                                         sizeof(ext2_acl_entry_short);
  55                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  56                                 break;
  57
  58                         case ACL_USER:
  59                         case ACL_GROUP:
  60                                 value = (char *)value + sizeof(ext2_acl_entry);
  61                                 if ((char *)value > end)
  62                                         goto fail;
  63                                 acl->a_entries[n].e_id =
  64                                         le32_to_cpu(entry->e_id);
  65                                 break;
  66
  67                         default:
  68                                 goto fail;
  69                 }
  70         }
  71         if (value != end)
  72                 goto fail;
  73         return acl;
  74
  75 fail:
  76         posix_acl_release(acl);
  77         return ERR_PTR(-EINVAL);
  78 }
  79
  80 /*
  81  * Convert from in-memory to filesystem representation.
  82  */
  83 static void *
  84 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  85 {
  86         ext2_acl_header *ext_acl;
  87         char *e;
  88         size_t n;
  89
  90         *size = ext2_acl_size(acl->a_count);
  91         ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
  92                 acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
  93         if (!ext_acl)
  94                 return ERR_PTR(-ENOMEM);
  95         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
  96         e = (char *)ext_acl + sizeof(ext2_acl_header);
  97         for (n=0; n < acl->a_count; n++) {
  98                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
  99                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 100                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 101                 switch(acl->a_entries[n].e_tag) {
 102                         case ACL_USER:
 103                         case ACL_GROUP:
 104                                 entry->e_id =
 105                                         cpu_to_le32(acl->a_entries[n].e_id);
 106                                 e += sizeof(ext2_acl_entry);
 107                                 break;
 108
 109                         case ACL_USER_OBJ:
 110                         case ACL_GROUP_OBJ:
 111                         case ACL_MASK:
 112                         case ACL_OTHER:
 113                                 e += sizeof(ext2_acl_entry_short);
 114                                 break;
 115
 116                         default:
 117                                 goto fail;
 118                 }
 119         }
 120         return (char *)ext_acl;
 121
 122 fail:
 123         kfree(ext_acl);
 124         return ERR_PTR(-EINVAL);
 125 }
 126
 127 static inline struct posix_acl *
 128 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 129 {
 130         struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
 131
 132         spin_lock(&inode->i_lock);
 133         if (*i_acl != EXT2_ACL_NOT_CACHED)
 134                 acl = posix_acl_dup(*i_acl);
 135         spin_unlock(&inode->i_lock);
 136
 137         return acl;
 138 }
 139
 140 static inline void
 141 ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 142                    struct posix_acl *acl)
 143 {
 144         spin_lock(&inode->i_lock);
 145         if (*i_acl != EXT2_ACL_NOT_CACHED)
 146                 posix_acl_release(*i_acl);
 147         *i_acl = posix_acl_dup(acl);
 148         spin_unlock(&inode->i_lock);
 149 }
 150
 151 /*
 152  * inode->i_sem: don't care
 153  */
 154 static struct posix_acl *
 155 ext2_get_acl(struct inode *inode, int type)
 156 {
 157         struct ext2_inode_info *ei = EXT2_I(inode);
 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, &ei->i_acl);
 169                         if (acl != EXT2_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, &ei->i_default_acl);
 176                         if (acl != EXT2_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         if (value)
 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_sem: 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;
 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         if (value)
 266                 kfree(value);
 267         if (!error) {
 268                 switch(type) {
 269                         case ACL_TYPE_ACCESS:
 270                                 ext2_iset_acl(inode, &ei->i_acl, acl);
 271                                 break;
 272
 273                         case ACL_TYPE_DEFAULT:
 274                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
 275                                 break;
 276                 }
 277         }
 278         return error;
 279 }
 280
 281 static int
 282 ext2_check_acl(struct inode *inode, int mask)
 283 {
 284         struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 285
 286         if (IS_ERR(acl))
 287                 return PTR_ERR(acl);
 288         if (acl) {
 289                 int error = posix_acl_permission(inode, acl, mask);
 290                 posix_acl_release(acl);
 291                 return error;
 292         }
 293
 294         return -EAGAIN;
 295 }
 296
 297 int
 298 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
 299 {
 300         return generic_permission(inode, mask, ext2_check_acl);
 301 }
 302
 303 /*
 304  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 305  *
 306  * dir->i_sem: down
 307  * inode->i_sem: up (access to inode is still exclusive)
 308  */
 309 int
 310 ext2_init_acl(struct inode *inode, struct inode *dir)
 311 {
 312         struct posix_acl *acl = NULL;
 313         int error = 0;
 314
 315         if (!S_ISLNK(inode->i_mode)) {
 316                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 317                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 318                         if (IS_ERR(acl))
 319                                 return PTR_ERR(acl);
 320                 }
 321                 if (!acl)
 322                         inode->i_mode &= ~current->fs->umask;
 323         }
 324         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 325                struct posix_acl *clone;
 326                mode_t mode;
 327
 328                 if (S_ISDIR(inode->i_mode)) {
 329                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 330                         if (error)
 331                                 goto cleanup;
 332                 }
 333                 clone = posix_acl_clone(acl, GFP_KERNEL);
 334                 error = -ENOMEM;
 335                 if (!clone)
 336                         goto cleanup;
 337                 mode = inode->i_mode;
 338                 error = posix_acl_create_masq(clone, &mode);
 339                 if (error >= 0) {
 340                         inode->i_mode = mode;
 341                         if (error > 0) {
 342                                 /* This is an extended ACL */
 343                                 error = ext2_set_acl(inode,
 344                                                      ACL_TYPE_ACCESS, clone);
 345                         }
 346                 }
 347                 posix_acl_release(clone);
 348         }
 349 cleanup:
 350        posix_acl_release(acl);
 351        return error;
 352 }
 353
 354 /*
 355  * Does chmod for an inode that may have an Access Control List. The
 356  * inode->i_mode field must be updated to the desired value by the caller
 357  * before calling this function.
 358  * Returns 0 on success, or a negative error number.
 359  *
 360  * We change the ACL rather than storing some ACL entries in the file
 361  * mode permission bits (which would be more efficient), because that
 362  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 363  * for directories) are added. There are no more bits available in the
 364  * file mode.
 365  *
 366  * inode->i_sem: down
 367  */
 368 int
 369 ext2_acl_chmod(struct inode *inode)
 370 {
 371         struct posix_acl *acl, *clone;
 372         int error;
 373
 374         if (!test_opt(inode->i_sb, POSIX_ACL))
 375                 return 0;
 376         if (S_ISLNK(inode->i_mode))
 377                 return -EOPNOTSUPP;
 378         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 379         if (IS_ERR(acl) || !acl)
 380                 return PTR_ERR(acl);
 381         clone = posix_acl_clone(acl, GFP_KERNEL);
 382         posix_acl_release(acl);
 383         if (!clone)
 384                 return -ENOMEM;
 385         error = posix_acl_chmod_masq(clone, inode->i_mode);
 386         if (!error)
 387                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 388         posix_acl_release(clone);
 389         return error;
 390 }
 391
 392 /*
 393  * Extended attribut handlers
 394  */
 395 static size_t
 396 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
 397                            const char *name, size_t name_len)
 398 {
 399         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 400
 401         if (!test_opt(inode->i_sb, POSIX_ACL))
 402                 return 0;
 403         if (list && size <= list_size)
 404                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 405         return size;
 406 }
 407
 408 static size_t
 409 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
 410                             const char *name, size_t name_len)
 411 {
 412         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 413
 414         if (!test_opt(inode->i_sb, POSIX_ACL))
 415                 return 0;
 416         if (list && size <= list_size)
 417                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 418         return size;
 419 }
 420
 421 static int
 422 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 423 {
 424         struct posix_acl *acl;
 425         int error;
 426
 427         if (!test_opt(inode->i_sb, POSIX_ACL))
 428                 return -EOPNOTSUPP;
 429
 430         acl = ext2_get_acl(inode, type);
 431         if (IS_ERR(acl))
 432                 return PTR_ERR(acl);
 433         if (acl == NULL)
 434                 return -ENODATA;
 435         error = posix_acl_to_xattr(acl, buffer, size);
 436         posix_acl_release(acl);
 437
 438         return error;
 439 }
 440
 441 static int
 442 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
 443                           void *buffer, size_t size)
 444 {
 445         if (strcmp(name, "") != 0)
 446                 return -EINVAL;
 447         return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 448 }
 449
 450 static int
 451 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
 452                            void *buffer, size_t size)
 453 {
 454         if (strcmp(name, "") != 0)
 455                 return -EINVAL;
 456         return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 457 }
 458
 459 static int
 460 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
 461                    size_t size)
 462 {
 463         struct posix_acl *acl;
 464         int error;
 465
 466         if (!test_opt(inode->i_sb, POSIX_ACL))
 467                 return -EOPNOTSUPP;
 468         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 469                 return -EPERM;
 470
 471         if (value) {
 472                 acl = posix_acl_from_xattr(value, size);
 473                 if (IS_ERR(acl))
 474                         return PTR_ERR(acl);
 475                 else if (acl) {
 476                         error = posix_acl_valid(acl);
 477                         if (error)
 478                                 goto release_and_out;
 479                 }
 480         } else
 481                 acl = NULL;
 482
 483         error = ext2_set_acl(inode, type, acl);
 484
 485 release_and_out:
 486         posix_acl_release(acl);
 487         return error;
 488 }
 489
 490 static int
 491 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
 492                           const void *value, size_t size, int flags)
 493 {
 494         if (strcmp(name, "") != 0)
 495                 return -EINVAL;
 496         return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 497 }
 498
 499 static int
 500 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
 501                            const void *value, size_t size, int flags)
 502 {
 503         if (strcmp(name, "") != 0)
 504                 return -EINVAL;
 505         return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 506 }
 507
 508 struct xattr_handler ext2_xattr_acl_access_handler = {
 509         .prefix = XATTR_NAME_ACL_ACCESS,
 510         .list   = ext2_xattr_list_acl_access,
 511         .get    = ext2_xattr_get_acl_access,
 512         .set    = ext2_xattr_set_acl_access,
 513 };
 514
 515 struct xattr_handler ext2_xattr_acl_default_handler = {
 516         .prefix = XATTR_NAME_ACL_DEFAULT,
 517         .list   = ext2_xattr_list_acl_default,
 518         .get    = ext2_xattr_get_acl_default,
 519         .set    = ext2_xattr_set_acl_default,
 520 };