fs/reiserfs/xattr_acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/capability.h>
   3 #include <linux/fs.h>
   4 #include <linux/posix_acl.h>
   5 #include "reiserfs.h"
   6 #include <linux/errno.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/xattr.h>
   9 #include <linux/slab.h>
  10 #include <linux/posix_acl_xattr.h>
  11 #include "xattr.h"
  12 #include "acl.h"
  13 #include <linux/uaccess.h>
  14
  15 static int __reiserfs_set_acl(struct reiserfs_transaction_handle *th,
  16                             struct inode *inode, int type,
  17                             struct posix_acl *acl);
  18
  19
  20 int
  21 reiserfs_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
  22                  struct posix_acl *acl, int type)
  23 {
  24         int error, error2;
  25         struct reiserfs_transaction_handle th;
  26         size_t jcreate_blocks;
  27         int size = acl ? posix_acl_xattr_size(acl->a_count) : 0;
  28         int update_mode = 0;
  29         umode_t mode = inode->i_mode;
  30
  31         /*
  32          * Pessimism: We can't assume that anything from the xattr root up
  33          * has been created.
  34          */
  35
  36         jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
  37                          reiserfs_xattr_nblocks(inode, size) * 2;
  38
  39         reiserfs_write_lock(inode->i_sb);
  40         error = journal_begin(&th, inode->i_sb, jcreate_blocks);
  41         reiserfs_write_unlock(inode->i_sb);
  42         if (error == 0) {
  43                 if (type == ACL_TYPE_ACCESS && acl) {
  44                         error = posix_acl_update_mode(&init_user_ns, inode,
  45                                                       &mode, &acl);
  46                         if (error)
  47                                 goto unlock;
  48                         update_mode = 1;
  49                 }
  50                 error = __reiserfs_set_acl(&th, inode, type, acl);
  51                 if (!error && update_mode)
  52                         inode->i_mode = mode;
  53 unlock:
  54                 reiserfs_write_lock(inode->i_sb);
  55                 error2 = journal_end(&th);
  56                 reiserfs_write_unlock(inode->i_sb);
  57                 if (error2)
  58                         error = error2;
  59         }
  60
  61         return error;
  62 }
  63
  64 /*
  65  * Convert from filesystem to in-memory representation.
  66  */
  67 static struct posix_acl *reiserfs_posix_acl_from_disk(const void *value, size_t size)
  68 {
  69         const char *end = (char *)value + size;
  70         int n, count;
  71         struct posix_acl *acl;
  72
  73         if (!value)
  74                 return NULL;
  75         if (size < sizeof(reiserfs_acl_header))
  76                 return ERR_PTR(-EINVAL);
  77         if (((reiserfs_acl_header *) value)->a_version !=
  78             cpu_to_le32(REISERFS_ACL_VERSION))
  79                 return ERR_PTR(-EINVAL);
  80         value = (char *)value + sizeof(reiserfs_acl_header);
  81         count = reiserfs_acl_count(size);
  82         if (count < 0)
  83                 return ERR_PTR(-EINVAL);
  84         if (count == 0)
  85                 return NULL;
  86         acl = posix_acl_alloc(count, GFP_NOFS);
  87         if (!acl)
  88                 return ERR_PTR(-ENOMEM);
  89         for (n = 0; n < count; n++) {
  90                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
  91                 if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
  92                         goto fail;
  93                 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
  94                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  95                 switch (acl->a_entries[n].e_tag) {
  96                 case ACL_USER_OBJ:
  97                 case ACL_GROUP_OBJ:
  98                 case ACL_MASK:
  99                 case ACL_OTHER:
 100                         value = (char *)value +
 101                             sizeof(reiserfs_acl_entry_short);
 102                         break;
 103
 104                 case ACL_USER:
 105                         value = (char *)value + sizeof(reiserfs_acl_entry);
 106                         if ((char *)value > end)
 107                                 goto fail;
 108                         acl->a_entries[n].e_uid =
 109                                 make_kuid(&init_user_ns,
 110                                           le32_to_cpu(entry->e_id));
 111                         break;
 112                 case ACL_GROUP:
 113                         value = (char *)value + sizeof(reiserfs_acl_entry);
 114                         if ((char *)value > end)
 115                                 goto fail;
 116                         acl->a_entries[n].e_gid =
 117                                 make_kgid(&init_user_ns,
 118                                           le32_to_cpu(entry->e_id));
 119                         break;
 120
 121                 default:
 122                         goto fail;
 123                 }
 124         }
 125         if (value != end)
 126                 goto fail;
 127         return acl;
 128
 129 fail:
 130         posix_acl_release(acl);
 131         return ERR_PTR(-EINVAL);
 132 }
 133
 134 /*
 135  * Convert from in-memory to filesystem representation.
 136  */
 137 static void *reiserfs_posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
 138 {
 139         reiserfs_acl_header *ext_acl;
 140         char *e;
 141         int n;
 142
 143         *size = reiserfs_acl_size(acl->a_count);
 144         ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
 145                                                   acl->a_count *
 146                                                   sizeof(reiserfs_acl_entry),
 147                                                   GFP_NOFS);
 148         if (!ext_acl)
 149                 return ERR_PTR(-ENOMEM);
 150         ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
 151         e = (char *)ext_acl + sizeof(reiserfs_acl_header);
 152         for (n = 0; n < acl->a_count; n++) {
 153                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 154                 reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
 155                 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
 156                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 157                 switch (acl->a_entries[n].e_tag) {
 158                 case ACL_USER:
 159                         entry->e_id = cpu_to_le32(
 160                                 from_kuid(&init_user_ns, acl_e->e_uid));
 161                         e += sizeof(reiserfs_acl_entry);
 162                         break;
 163                 case ACL_GROUP:
 164                         entry->e_id = cpu_to_le32(
 165                                 from_kgid(&init_user_ns, acl_e->e_gid));
 166                         e += sizeof(reiserfs_acl_entry);
 167                         break;
 168
 169                 case ACL_USER_OBJ:
 170                 case ACL_GROUP_OBJ:
 171                 case ACL_MASK:
 172                 case ACL_OTHER:
 173                         e += sizeof(reiserfs_acl_entry_short);
 174                         break;
 175
 176                 default:
 177                         goto fail;
 178                 }
 179         }
 180         return (char *)ext_acl;
 181
 182 fail:
 183         kfree(ext_acl);
 184         return ERR_PTR(-EINVAL);
 185 }
 186
 187 /*
 188  * Inode operation get_posix_acl().
 189  *
 190  * inode->i_mutex: down
 191  * BKL held [before 2.5.x]
 192  */
 193 struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
 194 {
 195         char *name, *value;
 196         struct posix_acl *acl;
 197         int size;
 198         int retval;
 199
 200         switch (type) {
 201         case ACL_TYPE_ACCESS:
 202                 name = XATTR_NAME_POSIX_ACL_ACCESS;
 203                 break;
 204         case ACL_TYPE_DEFAULT:
 205                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
 206                 break;
 207         default:
 208                 BUG();
 209         }
 210
 211         size = reiserfs_xattr_get(inode, name, NULL, 0);
 212         if (size < 0) {
 213                 if (size == -ENODATA || size == -ENOSYS)
 214                         return NULL;
 215                 return ERR_PTR(size);
 216         }
 217
 218         value = kmalloc(size, GFP_NOFS);
 219         if (!value)
 220                 return ERR_PTR(-ENOMEM);
 221
 222         retval = reiserfs_xattr_get(inode, name, value, size);
 223         if (retval == -ENODATA || retval == -ENOSYS) {
 224                 /*
 225                  * This shouldn't actually happen as it should have
 226                  * been caught above.. but just in case
 227                  */
 228                 acl = NULL;
 229         } else if (retval < 0) {
 230                 acl = ERR_PTR(retval);
 231         } else {
 232                 acl = reiserfs_posix_acl_from_disk(value, retval);
 233         }
 234
 235         kfree(value);
 236         return acl;
 237 }
 238
 239 /*
 240  * Inode operation set_posix_acl().
 241  *
 242  * inode->i_mutex: down
 243  * BKL held [before 2.5.x]
 244  */
 245 static int
 246 __reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
 247                  int type, struct posix_acl *acl)
 248 {
 249         char *name;
 250         void *value = NULL;
 251         size_t size = 0;
 252         int error;
 253
 254         switch (type) {
 255         case ACL_TYPE_ACCESS:
 256                 name = XATTR_NAME_POSIX_ACL_ACCESS;
 257                 break;
 258         case ACL_TYPE_DEFAULT:
 259                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
 260                 if (!S_ISDIR(inode->i_mode))
 261                         return acl ? -EACCES : 0;
 262                 break;
 263         default:
 264                 return -EINVAL;
 265         }
 266
 267         if (acl) {
 268                 value = reiserfs_posix_acl_to_disk(acl, &size);
 269                 if (IS_ERR(value))
 270                         return (int)PTR_ERR(value);
 271         }
 272
 273         error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
 274
 275         /*
 276          * Ensure that the inode gets dirtied if we're only using
 277          * the mode bits and an old ACL didn't exist. We don't need
 278          * to check if the inode is hashed here since we won't get
 279          * called by reiserfs_inherit_default_acl().
 280          */
 281         if (error == -ENODATA) {
 282                 error = 0;
 283                 if (type == ACL_TYPE_ACCESS) {
 284                         inode->i_ctime = current_time(inode);
 285                         mark_inode_dirty(inode);
 286                 }
 287         }
 288
 289         kfree(value);
 290
 291         if (!error)
 292                 set_cached_acl(inode, type, acl);
 293
 294         return error;
 295 }
 296
 297 /*
 298  * dir->i_mutex: locked,
 299  * inode is new and not released into the wild yet
 300  */
 301 int
 302 reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
 303                              struct inode *dir, struct dentry *dentry,
 304                              struct inode *inode)
 305 {
 306         struct posix_acl *default_acl, *acl;
 307         int err = 0;
 308
 309         /* ACLs only get applied to files and directories */
 310         if (S_ISLNK(inode->i_mode))
 311                 return 0;
 312
 313         /*
 314          * ACLs can only be used on "new" objects, so if it's an old object
 315          * there is nothing to inherit from
 316          */
 317         if (get_inode_sd_version(dir) == STAT_DATA_V1)
 318                 goto apply_umask;
 319
 320         /*
 321          * Don't apply ACLs to objects in the .reiserfs_priv tree.. This
 322          * would be useless since permissions are ignored, and a pain because
 323          * it introduces locking cycles
 324          */
 325         if (IS_PRIVATE(inode))
 326                 goto apply_umask;
 327
 328         err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 329         if (err)
 330                 return err;
 331
 332         if (default_acl) {
 333                 err = __reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
 334                                          default_acl);
 335                 posix_acl_release(default_acl);
 336         }
 337         if (acl) {
 338                 if (!err)
 339                         err = __reiserfs_set_acl(th, inode, ACL_TYPE_ACCESS,
 340                                                  acl);
 341                 posix_acl_release(acl);
 342         }
 343
 344         return err;
 345
 346 apply_umask:
 347         /* no ACL, apply umask */
 348         inode->i_mode &= ~current_umask();
 349         return err;
 350 }
 351
 352 /* This is used to cache the default acl before a new object is created.
 353  * The biggest reason for this is to get an idea of how many blocks will
 354  * actually be required for the create operation if we must inherit an ACL.
 355  * An ACL write can add up to 3 object creations and an additional file write
 356  * so we'd prefer not to reserve that many blocks in the journal if we can.
 357  * It also has the advantage of not loading the ACL with a transaction open,
 358  * this may seem silly, but if the owner of the directory is doing the
 359  * creation, the ACL may not be loaded since the permissions wouldn't require
 360  * it.
 361  * We return the number of blocks required for the transaction.
 362  */
 363 int reiserfs_cache_default_acl(struct inode *inode)
 364 {
 365         struct posix_acl *acl;
 366         int nblocks = 0;
 367
 368         if (IS_PRIVATE(inode))
 369                 return 0;
 370
 371         acl = get_acl(inode, ACL_TYPE_DEFAULT);
 372
 373         if (acl && !IS_ERR(acl)) {
 374                 int size = reiserfs_acl_size(acl->a_count);
 375
 376                 /* Other xattrs can be created during inode creation. We don't
 377                  * want to claim too many blocks, so we check to see if we
 378                  * need to create the tree to the xattrs, and then we
 379                  * just want two files. */
 380                 nblocks = reiserfs_xattr_jcreate_nblocks(inode);
 381                 nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
 382
 383                 REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
 384
 385                 /* We need to account for writes + bitmaps for two files */
 386                 nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
 387                 posix_acl_release(acl);
 388         }
 389
 390         return nblocks;
 391 }
 392
 393 /*
 394  * Called under i_mutex
 395  */
 396 int reiserfs_acl_chmod(struct inode *inode)
 397 {
 398         if (IS_PRIVATE(inode))
 399                 return 0;
 400         if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
 401             !reiserfs_posixacl(inode->i_sb))
 402                 return 0;
 403
 404         return posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
 405 }