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 <asm/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         /* Pessimism: We can't assume that anything from the xattr root up
  29          * has been created. */
  30
  31         jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
  32                          reiserfs_xattr_nblocks(inode, size) * 2;
  33
  34         reiserfs_write_lock(inode->i_sb);
  35         error = journal_begin(&th, inode->i_sb, jcreate_blocks);
  36         reiserfs_write_unlock(inode->i_sb);
  37         if (error == 0) {
  38                 error = __reiserfs_set_acl(&th, inode, type, acl);
  39                 reiserfs_write_lock(inode->i_sb);
  40                 error2 = journal_end(&th, inode->i_sb, jcreate_blocks);
  41                 reiserfs_write_unlock(inode->i_sb);
  42                 if (error2)
  43                         error = error2;
  44         }
  45
  46         return error;
  47 }
  48
  49 /*
  50  * Convert from filesystem to in-memory representation.
  51  */
  52 static struct posix_acl *reiserfs_posix_acl_from_disk(const void *value, size_t size)
  53 {
  54         const char *end = (char *)value + size;
  55         int n, count;
  56         struct posix_acl *acl;
  57
  58         if (!value)
  59                 return NULL;
  60         if (size < sizeof(reiserfs_acl_header))
  61                 return ERR_PTR(-EINVAL);
  62         if (((reiserfs_acl_header *) value)->a_version !=
  63             cpu_to_le32(REISERFS_ACL_VERSION))
  64                 return ERR_PTR(-EINVAL);
  65         value = (char *)value + sizeof(reiserfs_acl_header);
  66         count = reiserfs_acl_count(size);
  67         if (count < 0)
  68                 return ERR_PTR(-EINVAL);
  69         if (count == 0)
  70                 return NULL;
  71         acl = posix_acl_alloc(count, GFP_NOFS);
  72         if (!acl)
  73                 return ERR_PTR(-ENOMEM);
  74         for (n = 0; n < count; n++) {
  75                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
  76                 if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
  77                         goto fail;
  78                 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
  79                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  80                 switch (acl->a_entries[n].e_tag) {
  81                 case ACL_USER_OBJ:
  82                 case ACL_GROUP_OBJ:
  83                 case ACL_MASK:
  84                 case ACL_OTHER:
  85                         value = (char *)value +
  86                             sizeof(reiserfs_acl_entry_short);
  87                         break;
  88
  89                 case ACL_USER:
  90                         value = (char *)value + sizeof(reiserfs_acl_entry);
  91                         if ((char *)value > end)
  92                                 goto fail;
  93                         acl->a_entries[n].e_uid =
  94                                 make_kuid(&init_user_ns,
  95                                           le32_to_cpu(entry->e_id));
  96                         break;
  97                 case ACL_GROUP:
  98                         value = (char *)value + sizeof(reiserfs_acl_entry);
  99                         if ((char *)value > end)
 100                                 goto fail;
 101                         acl->a_entries[n].e_gid =
 102                                 make_kgid(&init_user_ns,
 103                                           le32_to_cpu(entry->e_id));
 104                         break;
 105
 106                 default:
 107                         goto fail;
 108                 }
 109         }
 110         if (value != end)
 111                 goto fail;
 112         return acl;
 113
 114       fail:
 115         posix_acl_release(acl);
 116         return ERR_PTR(-EINVAL);
 117 }
 118
 119 /*
 120  * Convert from in-memory to filesystem representation.
 121  */
 122 static void *reiserfs_posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
 123 {
 124         reiserfs_acl_header *ext_acl;
 125         char *e;
 126         int n;
 127
 128         *size = reiserfs_acl_size(acl->a_count);
 129         ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
 130                                                   acl->a_count *
 131                                                   sizeof(reiserfs_acl_entry),
 132                                                   GFP_NOFS);
 133         if (!ext_acl)
 134                 return ERR_PTR(-ENOMEM);
 135         ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
 136         e = (char *)ext_acl + sizeof(reiserfs_acl_header);
 137         for (n = 0; n < acl->a_count; n++) {
 138                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 139                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
 140                 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
 141                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 142                 switch (acl->a_entries[n].e_tag) {
 143                 case ACL_USER:
 144                         entry->e_id = cpu_to_le32(
 145                                 from_kuid(&init_user_ns, acl_e->e_uid));
 146                         e += sizeof(reiserfs_acl_entry);
 147                         break;
 148                 case ACL_GROUP:
 149                         entry->e_id = cpu_to_le32(
 150                                 from_kgid(&init_user_ns, acl_e->e_gid));
 151                         e += sizeof(reiserfs_acl_entry);
 152                         break;
 153
 154                 case ACL_USER_OBJ:
 155                 case ACL_GROUP_OBJ:
 156                 case ACL_MASK:
 157                 case ACL_OTHER:
 158                         e += sizeof(reiserfs_acl_entry_short);
 159                         break;
 160
 161                 default:
 162                         goto fail;
 163                 }
 164         }
 165         return (char *)ext_acl;
 166
 167       fail:
 168         kfree(ext_acl);
 169         return ERR_PTR(-EINVAL);
 170 }
 171
 172 /*
 173  * Inode operation get_posix_acl().
 174  *
 175  * inode->i_mutex: down
 176  * BKL held [before 2.5.x]
 177  */
 178 struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
 179 {
 180         char *name, *value;
 181         struct posix_acl *acl;
 182         int size;
 183         int retval;
 184
 185         switch (type) {
 186         case ACL_TYPE_ACCESS:
 187                 name = POSIX_ACL_XATTR_ACCESS;
 188                 break;
 189         case ACL_TYPE_DEFAULT:
 190                 name = POSIX_ACL_XATTR_DEFAULT;
 191                 break;
 192         default:
 193                 BUG();
 194         }
 195
 196         size = reiserfs_xattr_get(inode, name, NULL, 0);
 197         if (size < 0) {
 198                 if (size == -ENODATA || size == -ENOSYS) {
 199                         set_cached_acl(inode, type, NULL);
 200                         return NULL;
 201                 }
 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                 /* This shouldn't actually happen as it should have
 212                    been caught above.. but just in case */
 213                 acl = NULL;
 214         } else if (retval < 0) {
 215                 acl = ERR_PTR(retval);
 216         } else {
 217                 acl = reiserfs_posix_acl_from_disk(value, retval);
 218         }
 219         if (!IS_ERR(acl))
 220                 set_cached_acl(inode, type, acl);
 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 = POSIX_ACL_XATTR_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 = POSIX_ACL_XATTR_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 /* dir->i_mutex: locked,
 294  * inode is new and not released into the wild yet */
 295 int
 296 reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
 297                              struct inode *dir, struct dentry *dentry,
 298                              struct inode *inode)
 299 {
 300         struct posix_acl *default_acl, *acl;
 301         int err = 0;
 302
 303         /* ACLs only get applied to files and directories */
 304         if (S_ISLNK(inode->i_mode))
 305                 return 0;
 306
 307         /* ACLs can only be used on "new" objects, so if it's an old object
 308          * there is nothing to inherit from */
 309         if (get_inode_sd_version(dir) == STAT_DATA_V1)
 310                 goto apply_umask;
 311
 312         /* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
 313          * would be useless since permissions are ignored, and a pain because
 314          * it introduces locking cycles */
 315         if (IS_PRIVATE(dir)) {
 316                 inode->i_flags |= S_PRIVATE;
 317                 goto apply_umask;
 318         }
 319
 320         err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 321         if (err)
 322                 return err;
 323
 324         if (default_acl) {
 325                 err = __reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
 326                                          default_acl);
 327                 posix_acl_release(default_acl);
 328         }
 329         if (acl) {
 330                 if (!err)
 331                         err = __reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS,
 332                                                  acl);
 333                 posix_acl_release(acl);
 334         }
 335
 336         return err;
 337
 338       apply_umask:
 339         /* no ACL, apply umask */
 340         inode->i_mode &= ~current_umask();
 341         return err;
 342 }
 343
 344 /* This is used to cache the default acl before a new object is created.
 345  * The biggest reason for this is to get an idea of how many blocks will
 346  * actually be required for the create operation if we must inherit an ACL.
 347  * An ACL write can add up to 3 object creations and an additional file write
 348  * so we'd prefer not to reserve that many blocks in the journal if we can.
 349  * It also has the advantage of not loading the ACL with a transaction open,
 350  * this may seem silly, but if the owner of the directory is doing the
 351  * creation, the ACL may not be loaded since the permissions wouldn't require
 352  * it.
 353  * We return the number of blocks required for the transaction.
 354  */
 355 int reiserfs_cache_default_acl(struct inode *inode)
 356 {
 357         struct posix_acl *acl;
 358         int nblocks = 0;
 359
 360         if (IS_PRIVATE(inode))
 361                 return 0;
 362
 363         acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
 364
 365         if (acl && !IS_ERR(acl)) {
 366                 int size = reiserfs_acl_size(acl->a_count);
 367
 368                 /* Other xattrs can be created during inode creation. We don't
 369                  * want to claim too many blocks, so we check to see if we
 370                  * we need to create the tree to the xattrs, and then we
 371                  * just want two files. */
 372                 nblocks = reiserfs_xattr_jcreate_nblocks(inode);
 373                 nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
 374
 375                 REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 376
 377                 /* We need to account for writes + bitmaps for two files */
 378                 nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
 379                 posix_acl_release(acl);
 380         }
 381
 382         return nblocks;
 383 }
 384
 385 /*
 386  * Called under i_mutex
 387  */
 388 int reiserfs_acl_chmod(struct inode *inode)
 389 {
 390         if (IS_PRIVATE(inode))
 391                 return 0;
 392         if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
 393             !reiserfs_posixacl(inode->i_sb))
 394                 return 0;
 395
 396         return posix_acl_chmod(inode, inode->i_mode);
 397 }