fs/reiserfs/xattr_acl.c

   1 #include <linux/capability.h>
   2 #include <linux/fs.h>
   3 #include <linux/posix_acl.h>
   4 #include "reiserfs.h"
   5 #include <linux/errno.h>
   6 #include <linux/pagemap.h>
   7 #include <linux/xattr.h>
   8 #include <linux/slab.h>
   9 #include <linux/posix_acl_xattr.h>
  10 #include "xattr.h"
  11 #include "acl.h"
  12 #include <linux/uaccess.h>
  13
  14 static int __reiserfs_set_acl(struct reiserfs_transaction_handle *th,
  15                             struct inode *inode, int type,
  16                             struct posix_acl *acl);
  17
  18
  19 int
  20 reiserfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  21 {
  22         int error, error2;
  23         struct reiserfs_transaction_handle th;
  24         size_t jcreate_blocks;
  25         int size = acl ? posix_acl_xattr_size(acl->a_count) : 0;
  26
  27
  28         /*
  29          * Pessimism: We can't assume that anything from the xattr root up
  30          * has been created.
  31          */
  32
  33         jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
  34                          reiserfs_xattr_nblocks(inode, size) * 2;
  35
  36         reiserfs_write_lock(inode->i_sb);
  37         error = journal_begin(&th, inode->i_sb, jcreate_blocks);
  38         reiserfs_write_unlock(inode->i_sb);
  39         if (error == 0) {
  40                 error = __reiserfs_set_acl(&th, inode, type, acl);
  41                 reiserfs_write_lock(inode->i_sb);
  42                 error2 = journal_end(&th);
  43                 reiserfs_write_unlock(inode->i_sb);
  44                 if (error2)
  45                         error = error2;
  46         }
  47
  48         return error;
  49 }
  50
  51 /*
  52  * Convert from filesystem to in-memory representation.
  53  */
  54 static struct posix_acl *reiserfs_posix_acl_from_disk(const void *value, size_t size)
  55 {
  56         const char *end = (char *)value + size;
  57         int n, count;
  58         struct posix_acl *acl;
  59
  60         if (!value)
  61                 return NULL;
  62         if (size < sizeof(reiserfs_acl_header))
  63                 return ERR_PTR(-EINVAL);
  64         if (((reiserfs_acl_header *) value)->a_version !=
  65             cpu_to_le32(REISERFS_ACL_VERSION))
  66                 return ERR_PTR(-EINVAL);
  67         value = (char *)value + sizeof(reiserfs_acl_header);
  68         count = reiserfs_acl_count(size);
  69         if (count < 0)
  70                 return ERR_PTR(-EINVAL);
  71         if (count == 0)
  72                 return NULL;
  73         acl = posix_acl_alloc(count, GFP_NOFS);
  74         if (!acl)
  75                 return ERR_PTR(-ENOMEM);
  76         for (n = 0; n < count; n++) {
  77                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
  78                 if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
  79                         goto fail;
  80                 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
  81                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  82                 switch (acl->a_entries[n].e_tag) {
  83                 case ACL_USER_OBJ:
  84                 case ACL_GROUP_OBJ:
  85                 case ACL_MASK:
  86                 case ACL_OTHER:
  87                         value = (char *)value +
  88                             sizeof(reiserfs_acl_entry_short);
  89                         break;
  90
  91                 case ACL_USER:
  92                         value = (char *)value + sizeof(reiserfs_acl_entry);
  93                         if ((char *)value > end)
  94                                 goto fail;
  95                         acl->a_entries[n].e_uid =
  96                                 make_kuid(&init_user_ns,
  97                                           le32_to_cpu(entry->e_id));
  98                         break;
  99                 case ACL_GROUP:
 100                         value = (char *)value + sizeof(reiserfs_acl_entry);
 101                         if ((char *)value > end)
 102                                 goto fail;
 103                         acl->a_entries[n].e_gid =
 104                                 make_kgid(&init_user_ns,
 105                                           le32_to_cpu(entry->e_id));
 106                         break;
 107
 108                 default:
 109                         goto fail;
 110                 }
 111         }
 112         if (value != end)
 113                 goto fail;
 114         return acl;
 115
 116 fail:
 117         posix_acl_release(acl);
 118         return ERR_PTR(-EINVAL);
 119 }
 120
 121 /*
 122  * Convert from in-memory to filesystem representation.
 123  */
 124 static void *reiserfs_posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
 125 {
 126         reiserfs_acl_header *ext_acl;
 127         char *e;
 128         int n;
 129
 130         *size = reiserfs_acl_size(acl->a_count);
 131         ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
 132                                                   acl->a_count *
 133                                                   sizeof(reiserfs_acl_entry),
 134                                                   GFP_NOFS);
 135         if (!ext_acl)
 136                 return ERR_PTR(-ENOMEM);
 137         ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
 138         e = (char *)ext_acl + sizeof(reiserfs_acl_header);
 139         for (n = 0; n < acl->a_count; n++) {
 140                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 141                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
 142                 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
 143                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 144                 switch (acl->a_entries[n].e_tag) {
 145                 case ACL_USER:
 146                         entry->e_id = cpu_to_le32(
 147                                 from_kuid(&init_user_ns, acl_e->e_uid));
 148                         e += sizeof(reiserfs_acl_entry);
 149                         break;
 150                 case ACL_GROUP:
 151                         entry->e_id = cpu_to_le32(
 152                                 from_kgid(&init_user_ns, acl_e->e_gid));
 153                         e += sizeof(reiserfs_acl_entry);
 154                         break;
 155
 156                 case ACL_USER_OBJ:
 157                 case ACL_GROUP_OBJ:
 158                 case ACL_MASK:
 159                 case ACL_OTHER:
 160                         e += sizeof(reiserfs_acl_entry_short);
 161                         break;
 162
 163                 default:
 164                         goto fail;
 165                 }
 166         }
 167         return (char *)ext_acl;
 168
 169 fail:
 170         kfree(ext_acl);
 171         return ERR_PTR(-EINVAL);
 172 }
 173
 174 /*
 175  * Inode operation get_posix_acl().
 176  *
 177  * inode->i_mutex: down
 178  * BKL held [before 2.5.x]
 179  */
 180 struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
 181 {
 182         char *name, *value;
 183         struct posix_acl *acl;
 184         int size;
 185         int retval;
 186
 187         switch (type) {
 188         case ACL_TYPE_ACCESS:
 189                 name = XATTR_NAME_POSIX_ACL_ACCESS;
 190                 break;
 191         case ACL_TYPE_DEFAULT:
 192                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
 193                 break;
 194         default:
 195                 BUG();
 196         }
 197
 198         size = reiserfs_xattr_get(inode, name, NULL, 0);
 199         if (size < 0) {
 200                 if (size == -ENODATA || size == -ENOSYS)
 201                         return NULL;
 202                 return ERR_PTR(size);
 203         }
 204
 205         value = kmalloc(size, GFP_NOFS);
 206         if (!value)
 207                 return ERR_PTR(-ENOMEM);
 208
 209         retval = reiserfs_xattr_get(inode, name, value, size);
 210         if (retval == -ENODATA || retval == -ENOSYS) {
 211                 /*
 212                  * This shouldn't actually happen as it should have
 213                  * been caught above.. but just in case
 214                  */
 215                 acl = NULL;
 216         } else if (retval < 0) {
 217                 acl = ERR_PTR(retval);
 218         } else {
 219                 acl = reiserfs_posix_acl_from_disk(value, retval);
 220         }
 221
 222         kfree(value);
 223         return acl;
 224 }
 225
 226 /*
 227  * Inode operation set_posix_acl().
 228  *
 229  * inode->i_mutex: down
 230  * BKL held [before 2.5.x]
 231  */
 232 static int
 233 __reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
 234                  int type, struct posix_acl *acl)
 235 {
 236         char *name;
 237         void *value = NULL;
 238         size_t size = 0;
 239         int error;
 240
 241         switch (type) {
 242         case ACL_TYPE_ACCESS:
 243                 name = XATTR_NAME_POSIX_ACL_ACCESS;
 244                 if (acl) {
 245                         error = posix_acl_equiv_mode(acl, &inode->i_mode);
 246                         if (error < 0)
 247                                 return error;
 248                         else {
 249                                 if (error == 0)
 250                                         acl = NULL;
 251                         }
 252                 }
 253                 break;
 254         case ACL_TYPE_DEFAULT:
 255                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
 256                 if (!S_ISDIR(inode->i_mode))
 257                         return acl ? -EACCES : 0;
 258                 break;
 259         default:
 260                 return -EINVAL;
 261         }
 262
 263         if (acl) {
 264                 value = reiserfs_posix_acl_to_disk(acl, &size);
 265                 if (IS_ERR(value))
 266                         return (int)PTR_ERR(value);
 267         }
 268
 269         error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
 270
 271         /*
 272          * Ensure that the inode gets dirtied if we're only using
 273          * the mode bits and an old ACL didn't exist. We don't need
 274          * to check if the inode is hashed here since we won't get
 275          * called by reiserfs_inherit_default_acl().
 276          */
 277         if (error == -ENODATA) {
 278                 error = 0;
 279                 if (type == ACL_TYPE_ACCESS) {
 280                         inode->i_ctime = CURRENT_TIME_SEC;
 281                         mark_inode_dirty(inode);
 282                 }
 283         }
 284
 285         kfree(value);
 286
 287         if (!error)
 288                 set_cached_acl(inode, type, acl);
 289
 290         return error;
 291 }
 292
 293 /*
 294  * dir->i_mutex: locked,
 295  * inode is new and not released into the wild yet
 296  */
 297 int
 298 reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
 299                              struct inode *dir, struct dentry *dentry,
 300                              struct inode *inode)
 301 {
 302         struct posix_acl *default_acl, *acl;
 303         int err = 0;
 304
 305         /* ACLs only get applied to files and directories */
 306         if (S_ISLNK(inode->i_mode))
 307                 return 0;
 308
 309         /*
 310          * ACLs can only be used on "new" objects, so if it's an old object
 311          * there is nothing to inherit from
 312          */
 313         if (get_inode_sd_version(dir) == STAT_DATA_V1)
 314                 goto apply_umask;
 315
 316         /*
 317          * Don't apply ACLs to objects in the .reiserfs_priv tree.. This
 318          * would be useless since permissions are ignored, and a pain because
 319          * it introduces locking cycles
 320          */
 321         if (IS_PRIVATE(dir)) {
 322                 inode->i_flags |= S_PRIVATE;
 323                 goto apply_umask;
 324         }
 325
 326         err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 327         if (err)
 328                 return err;
 329
 330         if (default_acl) {
 331                 err = __reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
 332                                          default_acl);
 333                 posix_acl_release(default_acl);
 334         }
 335         if (acl) {
 336                 if (!err)
 337                         err = __reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS,
 338                                                  acl);
 339                 posix_acl_release(acl);
 340         }
 341
 342         return err;
 343
 344 apply_umask:
 345         /* no ACL, apply umask */
 346         inode->i_mode &= ~current_umask();
 347         return err;
 348 }
 349
 350 /* This is used to cache the default acl before a new object is created.
 351  * The biggest reason for this is to get an idea of how many blocks will
 352  * actually be required for the create operation if we must inherit an ACL.
 353  * An ACL write can add up to 3 object creations and an additional file write
 354  * so we'd prefer not to reserve that many blocks in the journal if we can.
 355  * It also has the advantage of not loading the ACL with a transaction open,
 356  * this may seem silly, but if the owner of the directory is doing the
 357  * creation, the ACL may not be loaded since the permissions wouldn't require
 358  * it.
 359  * We return the number of blocks required for the transaction.
 360  */
 361 int reiserfs_cache_default_acl(struct inode *inode)
 362 {
 363         struct posix_acl *acl;
 364         int nblocks = 0;
 365
 366         if (IS_PRIVATE(inode))
 367                 return 0;
 368
 369         acl = get_acl(inode, ACL_TYPE_DEFAULT);
 370
 371         if (acl && !IS_ERR(acl)) {
 372                 int size = reiserfs_acl_size(acl->a_count);
 373
 374                 /* Other xattrs can be created during inode creation. We don't
 375                  * want to claim too many blocks, so we check to see if we
 376                  * we need to create the tree to the xattrs, and then we
 377                  * just want two files. */
 378                 nblocks = reiserfs_xattr_jcreate_nblocks(inode);
 379                 nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
 380
 381                 REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 382
 383                 /* We need to account for writes + bitmaps for two files */
 384                 nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
 385                 posix_acl_release(acl);
 386         }
 387
 388         return nblocks;
 389 }
 390
 391 /*
 392  * Called under i_mutex
 393  */
 394 int reiserfs_acl_chmod(struct inode *inode)
 395 {
 396         if (IS_PRIVATE(inode))
 397                 return 0;
 398         if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
 399             !reiserfs_posixacl(inode->i_sb))
 400                 return 0;
 401
 402         return posix_acl_chmod(inode, inode->i_mode);
 403 }