fs/btrfs/acl.c

   1 /*
   2  * Copyright (C) 2007 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/string.h>
  21 #include <linux/xattr.h>
  22 #include <linux/posix_acl_xattr.h>
  23 #include <linux/posix_acl.h>
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26
  27 #include "ctree.h"
  28 #include "btrfs_inode.h"
  29 #include "xattr.h"
  30
  31 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
  32
  33 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  34 {
  35         int size;
  36         const char *name;
  37         char *value = NULL;
  38         struct posix_acl *acl;
  39
  40         if (!IS_POSIXACL(inode))
  41                 return NULL;
  42
  43         acl = get_cached_acl(inode, type);
  44         if (acl != ACL_NOT_CACHED)
  45                 return acl;
  46
  47         switch (type) {
  48         case ACL_TYPE_ACCESS:
  49                 name = POSIX_ACL_XATTR_ACCESS;
  50                 break;
  51         case ACL_TYPE_DEFAULT:
  52                 name = POSIX_ACL_XATTR_DEFAULT;
  53                 break;
  54         default:
  55                 BUG();
  56         }
  57
  58         size = __btrfs_getxattr(inode, name, "", 0);
  59         if (size > 0) {
  60                 value = kzalloc(size, GFP_NOFS);
  61                 if (!value)
  62                         return ERR_PTR(-ENOMEM);
  63                 size = __btrfs_getxattr(inode, name, value, size);
  64                 if (size > 0) {
  65                         acl = posix_acl_from_xattr(value, size);
  66                         if (IS_ERR(acl)) {
  67                                 kfree(value);
  68                                 return acl;
  69                         }
  70                         set_cached_acl(inode, type, acl);
  71                 }
  72                 kfree(value);
  73         } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  74                 /* FIXME, who returns -ENOENT?  I think nobody */
  75                 acl = NULL;
  76                 set_cached_acl(inode, type, acl);
  77         } else {
  78                 acl = ERR_PTR(-EIO);
  79         }
  80
  81         return acl;
  82 }
  83
  84 static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
  85                 void *value, size_t size, int type)
  86 {
  87         struct posix_acl *acl;
  88         int ret = 0;
  89
  90         if (!IS_POSIXACL(dentry->d_inode))
  91                 return -EOPNOTSUPP;
  92
  93         acl = btrfs_get_acl(dentry->d_inode, type);
  94
  95         if (IS_ERR(acl))
  96                 return PTR_ERR(acl);
  97         if (acl == NULL)
  98                 return -ENODATA;
  99         ret = posix_acl_to_xattr(acl, value, size);
 100         posix_acl_release(acl);
 101
 102         return ret;
 103 }
 104
 105 /*
 106  * Needs to be called with fs_mutex held
 107  */
 108 static int btrfs_set_acl(struct btrfs_trans_handle *trans,
 109                          struct inode *inode, struct posix_acl *acl, int type)
 110 {
 111         int ret, size = 0;
 112         const char *name;
 113         char *value = NULL;
 114         mode_t mode;
 115
 116         if (acl) {
 117                 ret = posix_acl_valid(acl);
 118                 if (ret < 0)
 119                         return ret;
 120                 ret = 0;
 121         }
 122
 123         switch (type) {
 124         case ACL_TYPE_ACCESS:
 125                 mode = inode->i_mode;
 126                 name = POSIX_ACL_XATTR_ACCESS;
 127                 if (acl) {
 128                         ret = posix_acl_equiv_mode(acl, &mode);
 129                         if (ret < 0)
 130                                 return ret;
 131                         inode->i_mode = mode;
 132                 }
 133                 ret = 0;
 134                 break;
 135         case ACL_TYPE_DEFAULT:
 136                 if (!S_ISDIR(inode->i_mode))
 137                         return acl ? -EINVAL : 0;
 138                 name = POSIX_ACL_XATTR_DEFAULT;
 139                 break;
 140         default:
 141                 return -EINVAL;
 142         }
 143
 144         if (acl) {
 145                 size = posix_acl_xattr_size(acl->a_count);
 146                 value = kmalloc(size, GFP_NOFS);
 147                 if (!value) {
 148                         ret = -ENOMEM;
 149                         goto out;
 150                 }
 151
 152                 ret = posix_acl_to_xattr(acl, value, size);
 153                 if (ret < 0)
 154                         goto out;
 155         }
 156
 157         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 158 out:
 159         kfree(value);
 160
 161         if (!ret)
 162                 set_cached_acl(inode, type, acl);
 163
 164         return ret;
 165 }
 166
 167 static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 168                 const void *value, size_t size, int flags, int type)
 169 {
 170         int ret;
 171         struct posix_acl *acl = NULL;
 172
 173         if (!is_owner_or_cap(dentry->d_inode))
 174                 return -EPERM;
 175
 176         if (!IS_POSIXACL(dentry->d_inode))
 177                 return -EOPNOTSUPP;
 178
 179         if (value) {
 180                 acl = posix_acl_from_xattr(value, size);
 181                 if (acl == NULL) {
 182                         value = NULL;
 183                         size = 0;
 184                 } else if (IS_ERR(acl)) {
 185                         return PTR_ERR(acl);
 186                 }
 187         }
 188
 189         ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
 190
 191         posix_acl_release(acl);
 192
 193         return ret;
 194 }
 195
 196 int btrfs_check_acl(struct inode *inode, int mask, unsigned int flags)
 197 {
 198         int error = -EAGAIN;
 199
 200         if (flags & IPERM_FLAG_RCU) {
 201                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 202                         error = -ECHILD;
 203
 204         } else {
 205                 struct posix_acl *acl;
 206                 acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 207                 if (IS_ERR(acl))
 208                         return PTR_ERR(acl);
 209                 if (acl) {
 210                         error = posix_acl_permission(inode, acl, mask);
 211                         posix_acl_release(acl);
 212                 }
 213         }
 214
 215         return error;
 216 }
 217
 218 /*
 219  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 220  * stuff has been fixed to work with that.  If the locking stuff changes, we
 221  * need to re-evaluate the acl locking stuff.
 222  */
 223 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 224                    struct inode *inode, struct inode *dir)
 225 {
 226         struct posix_acl *acl = NULL;
 227         int ret = 0;
 228
 229         /* this happens with subvols */
 230         if (!dir)
 231                 return 0;
 232
 233         if (!S_ISLNK(inode->i_mode)) {
 234                 if (IS_POSIXACL(dir)) {
 235                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 236                         if (IS_ERR(acl))
 237                                 return PTR_ERR(acl);
 238                 }
 239
 240                 if (!acl)
 241                         inode->i_mode &= ~current_umask();
 242         }
 243
 244         if (IS_POSIXACL(dir) && acl) {
 245                 struct posix_acl *clone;
 246                 mode_t mode;
 247
 248                 if (S_ISDIR(inode->i_mode)) {
 249                         ret = btrfs_set_acl(trans, inode, acl,
 250                                             ACL_TYPE_DEFAULT);
 251                         if (ret)
 252                                 goto failed;
 253                 }
 254                 clone = posix_acl_clone(acl, GFP_NOFS);
 255                 ret = -ENOMEM;
 256                 if (!clone)
 257                         goto failed;
 258
 259                 mode = inode->i_mode;
 260                 ret = posix_acl_create_masq(clone, &mode);
 261                 if (ret >= 0) {
 262                         inode->i_mode = mode;
 263                         if (ret > 0) {
 264                                 /* we need an acl */
 265                                 ret = btrfs_set_acl(trans, inode, clone,
 266                                                     ACL_TYPE_ACCESS);
 267                         }
 268                 }
 269                 posix_acl_release(clone);
 270         }
 271 failed:
 272         posix_acl_release(acl);
 273
 274         return ret;
 275 }
 276
 277 int btrfs_acl_chmod(struct inode *inode)
 278 {
 279         struct posix_acl *acl, *clone;
 280         int ret = 0;
 281
 282         if (S_ISLNK(inode->i_mode))
 283                 return -EOPNOTSUPP;
 284
 285         if (!IS_POSIXACL(inode))
 286                 return 0;
 287
 288         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 289         if (IS_ERR(acl) || !acl)
 290                 return PTR_ERR(acl);
 291
 292         clone = posix_acl_clone(acl, GFP_KERNEL);
 293         posix_acl_release(acl);
 294         if (!clone)
 295                 return -ENOMEM;
 296
 297         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 298         if (!ret)
 299                 ret = btrfs_set_acl(NULL, inode, clone, ACL_TYPE_ACCESS);
 300
 301         posix_acl_release(clone);
 302
 303         return ret;
 304 }
 305
 306 const struct xattr_handler btrfs_xattr_acl_default_handler = {
 307         .prefix = POSIX_ACL_XATTR_DEFAULT,
 308         .flags  = ACL_TYPE_DEFAULT,
 309         .get    = btrfs_xattr_acl_get,
 310         .set    = btrfs_xattr_acl_set,
 311 };
 312
 313 const struct xattr_handler btrfs_xattr_acl_access_handler = {
 314         .prefix = POSIX_ACL_XATTR_ACCESS,
 315         .flags  = ACL_TYPE_ACCESS,
 316         .get    = btrfs_xattr_acl_get,
 317         .set    = btrfs_xattr_acl_set,
 318 };
 319
 320 #else /* CONFIG_BTRFS_FS_POSIX_ACL */
 321
 322 int btrfs_acl_chmod(struct inode *inode)
 323 {
 324         return 0;
 325 }
 326
 327 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 328                    struct inode *inode, struct inode *dir)
 329 {
 330         return 0;
 331 }
 332
 333 #endif /* CONFIG_BTRFS_FS_POSIX_ACL */