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