fs/ext4/acl.c

   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 /*
 130  * Inode operation get_posix_acl().
 131  *
 132  * inode->i_mutex: don't care
 133  */
 134 struct posix_acl *
 135 ext4_get_acl(struct inode *inode, int type)
 136 {
 137         int name_index;
 138         char *value = NULL;
 139         struct posix_acl *acl;
 140         int retval;
 141
 142         if (!test_opt(inode->i_sb, POSIX_ACL))
 143                 return NULL;
 144
 145         acl = get_cached_acl(inode, type);
 146         if (acl != ACL_NOT_CACHED)
 147                 return acl;
 148
 149         switch (type) {
 150         case ACL_TYPE_ACCESS:
 151                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 152                 break;
 153         case ACL_TYPE_DEFAULT:
 154                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 155                 break;
 156         default:
 157                 BUG();
 158         }
 159         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 160         if (retval > 0) {
 161                 value = kmalloc(retval, GFP_NOFS);
 162                 if (!value)
 163                         return ERR_PTR(-ENOMEM);
 164                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 165         }
 166         if (retval > 0)
 167                 acl = ext4_acl_from_disk(value, retval);
 168         else if (retval == -ENODATA || retval == -ENOSYS)
 169                 acl = NULL;
 170         else
 171                 acl = ERR_PTR(retval);
 172         kfree(value);
 173
 174         if (!IS_ERR(acl))
 175                 set_cached_acl(inode, type, acl);
 176
 177         return acl;
 178 }
 179
 180 /*
 181  * Set the access or default ACL of an inode.
 182  *
 183  * inode->i_mutex: down unless called from ext4_new_inode
 184  */
 185 static int
 186 ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 187              struct posix_acl *acl)
 188 {
 189         int name_index;
 190         void *value = NULL;
 191         size_t size = 0;
 192         int error;
 193
 194         if (S_ISLNK(inode->i_mode))
 195                 return -EOPNOTSUPP;
 196
 197         switch (type) {
 198         case ACL_TYPE_ACCESS:
 199                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 200                 if (acl) {
 201                         error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
 202                         if (error)
 203                                 return error;
 204                         inode->i_ctime = ext4_current_time(inode);
 205                         ext4_mark_inode_dirty(handle, inode);
 206                 }
 207                 break;
 208
 209         case ACL_TYPE_DEFAULT:
 210                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 211                 if (!S_ISDIR(inode->i_mode))
 212                         return acl ? -EACCES : 0;
 213                 break;
 214
 215         default:
 216                 return -EINVAL;
 217         }
 218         if (acl) {
 219                 value = ext4_acl_to_disk(acl, &size);
 220                 if (IS_ERR(value))
 221                         return (int)PTR_ERR(value);
 222         }
 223
 224         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 225                                       value, size, 0);
 226
 227         kfree(value);
 228         if (!error)
 229                 set_cached_acl(inode, type, acl);
 230
 231         return error;
 232 }
 233
 234 /*
 235  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 236  *
 237  * dir->i_mutex: down
 238  * inode->i_mutex: up (access to inode is still exclusive)
 239  */
 240 int
 241 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 242 {
 243         struct posix_acl *acl = NULL;
 244         int error = 0;
 245
 246         if (!S_ISLNK(inode->i_mode)) {
 247                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 248                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
 249                         if (IS_ERR(acl))
 250                                 return PTR_ERR(acl);
 251                 }
 252                 if (!acl)
 253                         inode->i_mode &= ~current_umask();
 254         }
 255         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 256                 if (S_ISDIR(inode->i_mode)) {
 257                         error = ext4_set_acl(handle, inode,
 258                                              ACL_TYPE_DEFAULT, acl);
 259                         if (error)
 260                                 goto cleanup;
 261                 }
 262                 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
 263                 if (error < 0)
 264                         return error;
 265
 266                 if (error > 0) {
 267                         /* This is an extended ACL */
 268                         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 269                 }
 270         }
 271 cleanup:
 272         posix_acl_release(acl);
 273         return error;
 274 }
 275
 276 /*
 277  * Does chmod for an inode that may have an Access Control List. The
 278  * inode->i_mode field must be updated to the desired value by the caller
 279  * before calling this function.
 280  * Returns 0 on success, or a negative error number.
 281  *
 282  * We change the ACL rather than storing some ACL entries in the file
 283  * mode permission bits (which would be more efficient), because that
 284  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 285  * for directories) are added. There are no more bits available in the
 286  * file mode.
 287  *
 288  * inode->i_mutex: down
 289  */
 290 int
 291 ext4_acl_chmod(struct inode *inode)
 292 {
 293         struct posix_acl *acl;
 294         handle_t *handle;
 295         int retries = 0;
 296         int error;
 297
 298
 299         if (S_ISLNK(inode->i_mode))
 300                 return -EOPNOTSUPP;
 301         if (!test_opt(inode->i_sb, POSIX_ACL))
 302                 return 0;
 303         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
 304         if (IS_ERR(acl) || !acl)
 305                 return PTR_ERR(acl);
 306         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 307         if (error)
 308                 return error;
 309 retry:
 310         handle = ext4_journal_start(inode,
 311                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
 312         if (IS_ERR(handle)) {
 313                 error = PTR_ERR(handle);
 314                 ext4_std_error(inode->i_sb, error);
 315                 goto out;
 316         }
 317         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 318         ext4_journal_stop(handle);
 319         if (error == -ENOSPC &&
 320             ext4_should_retry_alloc(inode->i_sb, &retries))
 321                 goto retry;
 322 out:
 323         posix_acl_release(acl);
 324         return error;
 325 }
 326
 327 /*
 328  * Extended attribute handlers
 329  */
 330 static size_t
 331 ext4_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 332                            const char *name, size_t name_len, int type)
 333 {
 334         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 335
 336         if (!test_opt(dentry->d_sb, POSIX_ACL))
 337                 return 0;
 338         if (list && size <= list_len)
 339                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 340         return size;
 341 }
 342
 343 static size_t
 344 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 345                             const char *name, size_t name_len, int type)
 346 {
 347         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 348
 349         if (!test_opt(dentry->d_sb, POSIX_ACL))
 350                 return 0;
 351         if (list && size <= list_len)
 352                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 353         return size;
 354 }
 355
 356 static int
 357 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 358                    size_t size, int type)
 359 {
 360         struct posix_acl *acl;
 361         int error;
 362
 363         if (strcmp(name, "") != 0)
 364                 return -EINVAL;
 365         if (!test_opt(dentry->d_sb, POSIX_ACL))
 366                 return -EOPNOTSUPP;
 367
 368         acl = ext4_get_acl(dentry->d_inode, type);
 369         if (IS_ERR(acl))
 370                 return PTR_ERR(acl);
 371         if (acl == NULL)
 372                 return -ENODATA;
 373         error = posix_acl_to_xattr(acl, buffer, size);
 374         posix_acl_release(acl);
 375
 376         return error;
 377 }
 378
 379 static int
 380 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 381                    size_t size, int flags, int type)
 382 {
 383         struct inode *inode = dentry->d_inode;
 384         handle_t *handle;
 385         struct posix_acl *acl;
 386         int error, retries = 0;
 387
 388         if (strcmp(name, "") != 0)
 389                 return -EINVAL;
 390         if (!test_opt(inode->i_sb, POSIX_ACL))
 391                 return -EOPNOTSUPP;
 392         if (!inode_owner_or_capable(inode))
 393                 return -EPERM;
 394
 395         if (value) {
 396                 acl = posix_acl_from_xattr(value, size);
 397                 if (IS_ERR(acl))
 398                         return PTR_ERR(acl);
 399                 else if (acl) {
 400                         error = posix_acl_valid(acl);
 401                         if (error)
 402                                 goto release_and_out;
 403                 }
 404         } else
 405                 acl = NULL;
 406
 407 retry:
 408         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
 409         if (IS_ERR(handle)) {
 410                 error = PTR_ERR(handle);
 411                 goto release_and_out;
 412         }
 413         error = ext4_set_acl(handle, inode, type, acl);
 414         ext4_journal_stop(handle);
 415         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 416                 goto retry;
 417
 418 release_and_out:
 419         posix_acl_release(acl);
 420         return error;
 421 }
 422
 423 const struct xattr_handler ext4_xattr_acl_access_handler = {
 424         .prefix = POSIX_ACL_XATTR_ACCESS,
 425         .flags  = ACL_TYPE_ACCESS,
 426         .list   = ext4_xattr_list_acl_access,
 427         .get    = ext4_xattr_get_acl,
 428         .set    = ext4_xattr_set_acl,
 429 };
 430
 431 const struct xattr_handler ext4_xattr_acl_default_handler = {
 432         .prefix = POSIX_ACL_XATTR_DEFAULT,
 433         .flags  = ACL_TYPE_DEFAULT,
 434         .list   = ext4_xattr_list_acl_default,
 435         .get    = ext4_xattr_get_acl,
 436         .set    = ext4_xattr_set_acl,
 437 };