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 <linux/namei.h>
  12 #include <linux/vs_base.h>
  13 #include "ext2.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 ext2_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(ext2_acl_header))
  30                  return ERR_PTR(-EINVAL);
  31         if (((ext2_acl_header *)value)->a_version !=
  32             cpu_to_le32(EXT2_ACL_VERSION))
  33                 return ERR_PTR(-EINVAL);
  34         value = (char *)value + sizeof(ext2_acl_header);
  35         count = ext2_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_KERNEL);
  41         if (!acl)
  42                 return ERR_PTR(-ENOMEM);
  43         for (n=0; n < count; n++) {
  44                 ext2_acl_entry *entry =
  45                         (ext2_acl_entry *)value;
  46                 if ((char *)value + sizeof(ext2_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                 switch(acl->a_entries[n].e_tag) {
  51                         case ACL_USER_OBJ:
  52                         case ACL_GROUP_OBJ:
  53                         case ACL_MASK:
  54                         case ACL_OTHER:
  55                                 value = (char *)value +
  56                                         sizeof(ext2_acl_entry_short);
  57                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  58                                 break;
  59
  60                         case ACL_USER:
  61                         case ACL_GROUP:
  62                                 value = (char *)value + sizeof(ext2_acl_entry);
  63                                 if ((char *)value > end)
  64                                         goto fail;
  65                                 acl->a_entries[n].e_id =
  66                                         le32_to_cpu(entry->e_id);
  67                                 break;
  68
  69                         default:
  70                                 goto fail;
  71                 }
  72         }
  73         if (value != end)
  74                 goto fail;
  75         return acl;
  76
  77 fail:
  78         posix_acl_release(acl);
  79         return ERR_PTR(-EINVAL);
  80 }
  81
  82 /*
  83  * Convert from in-memory to filesystem representation.
  84  */
  85 static void *
  86 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  87 {
  88         ext2_acl_header *ext_acl;
  89         char *e;
  90         size_t n;
  91
  92         *size = ext2_acl_size(acl->a_count);
  93         ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
  94                 acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
  95         if (!ext_acl)
  96                 return ERR_PTR(-ENOMEM);
  97         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
  98         e = (char *)ext_acl + sizeof(ext2_acl_header);
  99         for (n=0; n < acl->a_count; n++) {
 100                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
 101                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 102                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 103                 switch(acl->a_entries[n].e_tag) {
 104                         case ACL_USER:
 105                         case ACL_GROUP:
 106                                 entry->e_id =
 107                                         cpu_to_le32(acl->a_entries[n].e_id);
 108                                 e += sizeof(ext2_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(ext2_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 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 131 {
 132         struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
 133
 134         spin_lock(&inode->i_lock);
 135         if (*i_acl != EXT2_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 ext2_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 != EXT2_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->i_sem: don't care
 155  */
 156 static struct posix_acl *
 157 ext2_get_acl(struct inode *inode, int type)
 158 {
 159         struct ext2_inode_info *ei = EXT2_I(inode);
 160         int name_index;
 161         char *value = NULL;
 162         struct posix_acl *acl;
 163         int retval;
 164
 165         if (!test_opt(inode->i_sb, POSIX_ACL))
 166                 return NULL;
 167
 168         switch(type) {
 169                 case ACL_TYPE_ACCESS:
 170                         acl = ext2_iget_acl(inode, &ei->i_acl);
 171                         if (acl != EXT2_ACL_NOT_CACHED)
 172                                 return acl;
 173                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 174                         break;
 175
 176                 case ACL_TYPE_DEFAULT:
 177                         acl = ext2_iget_acl(inode, &ei->i_default_acl);
 178                         if (acl != EXT2_ACL_NOT_CACHED)
 179                                 return acl;
 180                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 181                         break;
 182
 183                 default:
 184                         return ERR_PTR(-EINVAL);
 185         }
 186         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 187         if (retval > 0) {
 188                 value = kmalloc(retval, GFP_KERNEL);
 189                 if (!value)
 190                         return ERR_PTR(-ENOMEM);
 191                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 192         }
 193         if (retval > 0)
 194                 acl = ext2_acl_from_disk(value, retval);
 195         else if (retval == -ENODATA || retval == -ENOSYS)
 196                 acl = NULL;
 197         else
 198                 acl = ERR_PTR(retval);
 199         if (value)
 200                 kfree(value);
 201
 202         if (!IS_ERR(acl)) {
 203                 switch(type) {
 204                         case ACL_TYPE_ACCESS:
 205                                 ext2_iset_acl(inode, &ei->i_acl, acl);
 206                                 break;
 207
 208                         case ACL_TYPE_DEFAULT:
 209                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
 210                                 break;
 211                 }
 212         }
 213         return acl;
 214 }
 215
 216 /*
 217  * inode->i_sem: down
 218  */
 219 static int
 220 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 221 {
 222         struct ext2_inode_info *ei = EXT2_I(inode);
 223         int name_index;
 224         void *value = NULL;
 225         size_t size;
 226         int error;
 227
 228         if (S_ISLNK(inode->i_mode))
 229                 return -EOPNOTSUPP;
 230         if (!test_opt(inode->i_sb, POSIX_ACL))
 231                 return 0;
 232
 233         switch(type) {
 234                 case ACL_TYPE_ACCESS:
 235                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 236                         if (acl) {
 237                                 mode_t mode = inode->i_mode;
 238                                 error = posix_acl_equiv_mode(acl, &mode);
 239                                 if (error < 0)
 240                                         return error;
 241                                 else {
 242                                         inode->i_mode = mode;
 243                                         mark_inode_dirty(inode);
 244                                         if (error == 0)
 245                                                 acl = NULL;
 246                                 }
 247                         }
 248                         break;
 249
 250                 case ACL_TYPE_DEFAULT:
 251                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 252                         if (!S_ISDIR(inode->i_mode))
 253                                 return acl ? -EACCES : 0;
 254                         break;
 255
 256                 default:
 257                         return -EINVAL;
 258         }
 259         if (acl) {
 260                 value = ext2_acl_to_disk(acl, &size);
 261                 if (IS_ERR(value))
 262                         return (int)PTR_ERR(value);
 263         }
 264
 265         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 266
 267         if (value)
 268                 kfree(value);
 269         if (!error) {
 270                 switch(type) {
 271                         case ACL_TYPE_ACCESS:
 272                                 ext2_iset_acl(inode, &ei->i_acl, acl);
 273                                 break;
 274
 275                         case ACL_TYPE_DEFAULT:
 276                                 ext2_iset_acl(inode, &ei->i_default_acl, acl);
 277                                 break;
 278                 }
 279         }
 280         return error;
 281 }
 282
 283 static int
 284 ext2_check_acl(struct inode *inode, int mask)
 285 {
 286         struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 287
 288         if (IS_ERR(acl))
 289                 return PTR_ERR(acl);
 290         if (acl) {
 291                 int error = posix_acl_permission(inode, acl, mask);
 292                 posix_acl_release(acl);
 293                 return error;
 294         }
 295
 296         return -EAGAIN;
 297 }
 298
 299 int
 300 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
 301 {
 302         return generic_permission(inode, mask, ext2_check_acl);
 303 }
 304
 305 /*
 306  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 307  *
 308  * dir->i_sem: down
 309  * inode->i_sem: up (access to inode is still exclusive)
 310  */
 311 int
 312 ext2_init_acl(struct inode *inode, struct inode *dir)
 313 {
 314         struct posix_acl *acl = NULL;
 315         int error = 0;
 316
 317         if (!S_ISLNK(inode->i_mode)) {
 318                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 319                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 320                         if (IS_ERR(acl))
 321                                 return PTR_ERR(acl);
 322                 }
 323                 if (!acl)
 324                         inode->i_mode &= ~current->fs->umask;
 325         }
 326         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 327                struct posix_acl *clone;
 328                mode_t mode;
 329
 330                 if (S_ISDIR(inode->i_mode)) {
 331                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 332                         if (error)
 333                                 goto cleanup;
 334                 }
 335                 clone = posix_acl_clone(acl, GFP_KERNEL);
 336                 error = -ENOMEM;
 337                 if (!clone)
 338                         goto cleanup;
 339                 mode = inode->i_mode;
 340                 error = posix_acl_create_masq(clone, &mode);
 341                 if (error >= 0) {
 342                         inode->i_mode = mode;
 343                         if (error > 0) {
 344                                 /* This is an extended ACL */
 345                                 error = ext2_set_acl(inode,
 346                                                      ACL_TYPE_ACCESS, clone);
 347                         }
 348                 }
 349                 posix_acl_release(clone);
 350         }
 351 cleanup:
 352        posix_acl_release(acl);
 353        return error;
 354 }
 355
 356 /*
 357  * Does chmod for an inode that may have an Access Control List. The
 358  * inode->i_mode field must be updated to the desired value by the caller
 359  * before calling this function.
 360  * Returns 0 on success, or a negative error number.
 361  *
 362  * We change the ACL rather than storing some ACL entries in the file
 363  * mode permission bits (which would be more efficient), because that
 364  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 365  * for directories) are added. There are no more bits available in the
 366  * file mode.
 367  *
 368  * inode->i_sem: down
 369  */
 370 int
 371 ext2_acl_chmod(struct inode *inode)
 372 {
 373         struct posix_acl *acl, *clone;
 374         int error;
 375
 376         if (!test_opt(inode->i_sb, POSIX_ACL))
 377                 return 0;
 378         if (S_ISLNK(inode->i_mode))
 379                 return -EOPNOTSUPP;
 380         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 381         if (IS_ERR(acl) || !acl)
 382                 return PTR_ERR(acl);
 383         clone = posix_acl_clone(acl, GFP_KERNEL);
 384         posix_acl_release(acl);
 385         if (!clone)
 386                 return -ENOMEM;
 387         error = posix_acl_chmod_masq(clone, inode->i_mode);
 388         if (!error)
 389                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 390         posix_acl_release(clone);
 391         return error;
 392 }
 393
 394 /*
 395  * Extended attribut handlers
 396  */
 397 static size_t
 398 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
 399                            const char *name, size_t name_len)
 400 {
 401         const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
 402
 403         if (!test_opt(inode->i_sb, POSIX_ACL))
 404                 return 0;
 405         if (list && size <= list_size)
 406                 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
 407         return size;
 408 }
 409
 410 static size_t
 411 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
 412                             const char *name, size_t name_len)
 413 {
 414         const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
 415
 416         if (!test_opt(inode->i_sb, POSIX_ACL))
 417                 return 0;
 418         if (list && size <= list_size)
 419                 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
 420         return size;
 421 }
 422
 423 static int
 424 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 425 {
 426         struct posix_acl *acl;
 427         int error;
 428
 429         if (!test_opt(inode->i_sb, POSIX_ACL))
 430                 return -EOPNOTSUPP;
 431
 432         acl = ext2_get_acl(inode, type);
 433         if (IS_ERR(acl))
 434                 return PTR_ERR(acl);
 435         if (acl == NULL)
 436                 return -ENODATA;
 437         error = posix_acl_to_xattr(acl, buffer, size);
 438         posix_acl_release(acl);
 439
 440         return error;
 441 }
 442
 443 static int
 444 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
 445                           void *buffer, size_t size)
 446 {
 447         if (strcmp(name, "") != 0)
 448                 return -EINVAL;
 449         return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 450 }
 451
 452 static int
 453 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
 454                            void *buffer, size_t size)
 455 {
 456         if (strcmp(name, "") != 0)
 457                 return -EINVAL;
 458         return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 459 }
 460
 461 static int
 462 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
 463                    size_t size)
 464 {
 465         struct posix_acl *acl;
 466         int error;
 467
 468         if (!test_opt(inode->i_sb, POSIX_ACL))
 469                 return -EOPNOTSUPP;
 470         if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
 471                 return -EPERM;
 472
 473         if (value) {
 474                 acl = posix_acl_from_xattr(value, size);
 475                 if (IS_ERR(acl))
 476                         return PTR_ERR(acl);
 477                 else if (acl) {
 478                         error = posix_acl_valid(acl);
 479                         if (error)
 480                                 goto release_and_out;
 481                 }
 482         } else
 483                 acl = NULL;
 484
 485         error = ext2_set_acl(inode, type, acl);
 486
 487 release_and_out:
 488         posix_acl_release(acl);
 489         return error;
 490 }
 491
 492 static int
 493 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
 494                           const void *value, size_t size, int flags)
 495 {
 496         if (strcmp(name, "") != 0)
 497                 return -EINVAL;
 498         return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 499 }
 500
 501 static int
 502 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
 503                            const void *value, size_t size, int flags)
 504 {
 505         if (strcmp(name, "") != 0)
 506                 return -EINVAL;
 507         return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 508 }
 509
 510 struct xattr_handler ext2_xattr_acl_access_handler = {
 511         .prefix = XATTR_NAME_ACL_ACCESS,
 512         .list   = ext2_xattr_list_acl_access,
 513         .get    = ext2_xattr_get_acl_access,
 514         .set    = ext2_xattr_set_acl_access,
 515 };
 516
 517 struct xattr_handler ext2_xattr_acl_default_handler = {
 518         .prefix = XATTR_NAME_ACL_DEFAULT,
 519         .list   = ext2_xattr_list_acl_default,
 520         .get    = ext2_xattr_get_acl_default,
 521         .set    = ext2_xattr_set_acl_default,
 522 };