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                         break;
  59
  60                 case ACL_USER:
  61                         value = (char *)value + sizeof(ext4_acl_entry);
  62                         if ((char *)value > end)
  63                                 goto fail;
  64                         acl->a_entries[n].e_uid =
  65                                 make_kuid(&init_user_ns,
  66                                           le32_to_cpu(entry->e_id));
  67                         break;
  68                 case ACL_GROUP:
  69                         value = (char *)value + sizeof(ext4_acl_entry);
  70                         if ((char *)value > end)
  71                                 goto fail;
  72                         acl->a_entries[n].e_gid =
  73                                 make_kgid(&init_user_ns,
  74                                           le32_to_cpu(entry->e_id));
  75                         break;
  76
  77                 default:
  78                         goto fail;
  79                 }
  80         }
  81         if (value != end)
  82                 goto fail;
  83         return acl;
  84
  85 fail:
  86         posix_acl_release(acl);
  87         return ERR_PTR(-EINVAL);
  88 }
  89
  90 /*
  91  * Convert from in-memory to filesystem representation.
  92  */
  93 static void *
  94 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  95 {
  96         ext4_acl_header *ext_acl;
  97         char *e;
  98         size_t n;
  99
 100         *size = ext4_acl_size(acl->a_count);
 101         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
 102                         sizeof(ext4_acl_entry), GFP_NOFS);
 103         if (!ext_acl)
 104                 return ERR_PTR(-ENOMEM);
 105         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
 106         e = (char *)ext_acl + sizeof(ext4_acl_header);
 107         for (n = 0; n < acl->a_count; n++) {
 108                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 109                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
 110                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 111                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 112                 switch (acl_e->e_tag) {
 113                 case ACL_USER:
 114                         entry->e_id = cpu_to_le32(
 115                                 from_kuid(&init_user_ns, acl_e->e_uid));
 116                         e += sizeof(ext4_acl_entry);
 117                         break;
 118                 case ACL_GROUP:
 119                         entry->e_id = cpu_to_le32(
 120                                 from_kgid(&init_user_ns, acl_e->e_gid));
 121                         e += sizeof(ext4_acl_entry);
 122                         break;
 123
 124                 case ACL_USER_OBJ:
 125                 case ACL_GROUP_OBJ:
 126                 case ACL_MASK:
 127                 case ACL_OTHER:
 128                         e += sizeof(ext4_acl_entry_short);
 129                         break;
 130
 131                 default:
 132                         goto fail;
 133                 }
 134         }
 135         return (char *)ext_acl;
 136
 137 fail:
 138         kfree(ext_acl);
 139         return ERR_PTR(-EINVAL);
 140 }
 141
 142 /*
 143  * Inode operation get_posix_acl().
 144  *
 145  * inode->i_mutex: don't care
 146  */
 147 struct posix_acl *
 148 ext4_get_acl(struct inode *inode, int type)
 149 {
 150         int name_index;
 151         char *value = NULL;
 152         struct posix_acl *acl;
 153         int retval;
 154
 155         if (!test_opt(inode->i_sb, POSIX_ACL))
 156                 return NULL;
 157
 158         acl = get_cached_acl(inode, type);
 159         if (acl != ACL_NOT_CACHED)
 160                 return acl;
 161
 162         switch (type) {
 163         case ACL_TYPE_ACCESS:
 164                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 165                 break;
 166         case ACL_TYPE_DEFAULT:
 167                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 168                 break;
 169         default:
 170                 BUG();
 171         }
 172         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 173         if (retval > 0) {
 174                 value = kmalloc(retval, GFP_NOFS);
 175                 if (!value)
 176                         return ERR_PTR(-ENOMEM);
 177                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 178         }
 179         if (retval > 0)
 180                 acl = ext4_acl_from_disk(value, retval);
 181         else if (retval == -ENODATA || retval == -ENOSYS)
 182                 acl = NULL;
 183         else
 184                 acl = ERR_PTR(retval);
 185         kfree(value);
 186
 187         if (!IS_ERR(acl))
 188                 set_cached_acl(inode, type, acl);
 189
 190         return acl;
 191 }
 192
 193 /*
 194  * Set the access or default ACL of an inode.
 195  *
 196  * inode->i_mutex: down unless called from ext4_new_inode
 197  */
 198 static int
 199 ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 200              struct posix_acl *acl)
 201 {
 202         int name_index;
 203         void *value = NULL;
 204         size_t size = 0;
 205         int error;
 206
 207         if (S_ISLNK(inode->i_mode))
 208                 return -EOPNOTSUPP;
 209
 210         switch (type) {
 211         case ACL_TYPE_ACCESS:
 212                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 213                 if (acl) {
 214                         error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
 215                         if (error < 0)
 216                                 return error;
 217                         inode->i_ctime = ext4_current_time(inode);
 218                         ext4_mark_inode_dirty(handle, inode);
 219                 }
 220                 break;
 221
 222         case ACL_TYPE_DEFAULT:
 223                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 224                 if (!S_ISDIR(inode->i_mode))
 225                         return acl ? -EACCES : 0;
 226                 break;
 227
 228         default:
 229                 return -EINVAL;
 230         }
 231         if (acl) {
 232                 value = ext4_acl_to_disk(acl, &size);
 233                 if (IS_ERR(value))
 234                         return (int)PTR_ERR(value);
 235         }
 236
 237         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 238                                       value, size, 0);
 239
 240         kfree(value);
 241         if (!error)
 242                 set_cached_acl(inode, type, acl);
 243
 244         return error;
 245 }
 246
 247 /*
 248  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 249  *
 250  * dir->i_mutex: down
 251  * inode->i_mutex: up (access to inode is still exclusive)
 252  */
 253 int
 254 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 255 {
 256         struct posix_acl *acl = NULL;
 257         int error = 0;
 258
 259         if (!S_ISLNK(inode->i_mode)) {
 260                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 261                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
 262                         if (IS_ERR(acl))
 263                                 return PTR_ERR(acl);
 264                 }
 265                 if (!acl)
 266                         inode->i_mode &= ~current_umask();
 267         }
 268         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 269                 if (S_ISDIR(inode->i_mode)) {
 270                         error = ext4_set_acl(handle, inode,
 271                                              ACL_TYPE_DEFAULT, acl);
 272                         if (error)
 273                                 goto cleanup;
 274                 }
 275                 error = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
 276                 if (error < 0)
 277                         return error;
 278
 279                 if (error > 0) {
 280                         /* This is an extended ACL */
 281                         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 282                 }
 283         }
 284 cleanup:
 285         posix_acl_release(acl);
 286         return error;
 287 }
 288
 289 /*
 290  * Does chmod for an inode that may have an Access Control List. The
 291  * inode->i_mode field must be updated to the desired value by the caller
 292  * before calling this function.
 293  * Returns 0 on success, or a negative error number.
 294  *
 295  * We change the ACL rather than storing some ACL entries in the file
 296  * mode permission bits (which would be more efficient), because that
 297  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 298  * for directories) are added. There are no more bits available in the
 299  * file mode.
 300  *
 301  * inode->i_mutex: down
 302  */
 303 int
 304 ext4_acl_chmod(struct inode *inode)
 305 {
 306         struct posix_acl *acl;
 307         handle_t *handle;
 308         int retries = 0;
 309         int error;
 310
 311
 312         if (S_ISLNK(inode->i_mode))
 313                 return -EOPNOTSUPP;
 314         if (!test_opt(inode->i_sb, POSIX_ACL))
 315                 return 0;
 316         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
 317         if (IS_ERR(acl) || !acl)
 318                 return PTR_ERR(acl);
 319         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 320         if (error)
 321                 return error;
 322 retry:
 323         handle = ext4_journal_start(inode, EXT4_HT_XATTR,
 324                                     ext4_jbd2_credits_xattr(inode));
 325         if (IS_ERR(handle)) {
 326                 error = PTR_ERR(handle);
 327                 ext4_std_error(inode->i_sb, error);
 328                 goto out;
 329         }
 330         error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, acl);
 331         ext4_journal_stop(handle);
 332         if (error == -ENOSPC &&
 333             ext4_should_retry_alloc(inode->i_sb, &retries))
 334                 goto retry;
 335 out:
 336         posix_acl_release(acl);
 337         return error;
 338 }
 339
 340 /*
 341  * Extended attribute handlers
 342  */
 343 static size_t
 344 ext4_xattr_list_acl_access(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_ACCESS);
 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_ACCESS, size);
 353         return size;
 354 }
 355
 356 static size_t
 357 ext4_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 358                             const char *name, size_t name_len, int type)
 359 {
 360         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 361
 362         if (!test_opt(dentry->d_sb, POSIX_ACL))
 363                 return 0;
 364         if (list && size <= list_len)
 365                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 366         return size;
 367 }
 368
 369 static int
 370 ext4_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 371                    size_t size, int type)
 372 {
 373         struct posix_acl *acl;
 374         int error;
 375
 376         if (strcmp(name, "") != 0)
 377                 return -EINVAL;
 378         if (!test_opt(dentry->d_sb, POSIX_ACL))
 379                 return -EOPNOTSUPP;
 380
 381         acl = ext4_get_acl(dentry->d_inode, type);
 382         if (IS_ERR(acl))
 383                 return PTR_ERR(acl);
 384         if (acl == NULL)
 385                 return -ENODATA;
 386         error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 387         posix_acl_release(acl);
 388
 389         return error;
 390 }
 391
 392 static int
 393 ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 394                    size_t size, int flags, int type)
 395 {
 396         struct inode *inode = dentry->d_inode;
 397         handle_t *handle;
 398         struct posix_acl *acl;
 399         int error, retries = 0;
 400
 401         if (strcmp(name, "") != 0)
 402                 return -EINVAL;
 403         if (!test_opt(inode->i_sb, POSIX_ACL))
 404                 return -EOPNOTSUPP;
 405         if (!inode_owner_or_capable(inode))
 406                 return -EPERM;
 407
 408         if (value) {
 409                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 410                 if (IS_ERR(acl))
 411                         return PTR_ERR(acl);
 412                 else if (acl) {
 413                         error = posix_acl_valid(acl);
 414                         if (error)
 415                                 goto release_and_out;
 416                 }
 417         } else
 418                 acl = NULL;
 419
 420 retry:
 421         handle = ext4_journal_start(inode, EXT4_HT_XATTR,
 422                                     ext4_jbd2_credits_xattr(inode));
 423         if (IS_ERR(handle)) {
 424                 error = PTR_ERR(handle);
 425                 goto release_and_out;
 426         }
 427         error = ext4_set_acl(handle, inode, type, acl);
 428         ext4_journal_stop(handle);
 429         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 430                 goto retry;
 431
 432 release_and_out:
 433         posix_acl_release(acl);
 434         return error;
 435 }
 436
 437 const struct xattr_handler ext4_xattr_acl_access_handler = {
 438         .prefix = POSIX_ACL_XATTR_ACCESS,
 439         .flags  = ACL_TYPE_ACCESS,
 440         .list   = ext4_xattr_list_acl_access,
 441         .get    = ext4_xattr_get_acl,
 442         .set    = ext4_xattr_set_acl,
 443 };
 444
 445 const struct xattr_handler ext4_xattr_acl_default_handler = {
 446         .prefix = POSIX_ACL_XATTR_DEFAULT,
 447         .flags  = ACL_TYPE_DEFAULT,
 448         .list   = ext4_xattr_list_acl_default,
 449         .get    = ext4_xattr_get_acl,
 450         .set    = ext4_xattr_set_acl,
 451 };