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
  26 #include "ctree.h"
  27 #include "btrfs_inode.h"
  28 #include "xattr.h"
  29
  30 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
  31
  32 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  33 {
  34         int size;
  35         const char *name;
  36         char *value = NULL;
  37         struct posix_acl *acl;
  38
  39         acl = get_cached_acl(inode, type);
  40         if (acl != ACL_NOT_CACHED)
  41                 return acl;
  42
  43         switch (type) {
  44         case ACL_TYPE_ACCESS:
  45                 name = POSIX_ACL_XATTR_ACCESS;
  46                 break;
  47         case ACL_TYPE_DEFAULT:
  48                 name = POSIX_ACL_XATTR_DEFAULT;
  49                 break;
  50         default:
  51                 BUG();
  52         }
  53
  54         size = __btrfs_getxattr(inode, name, "", 0);
  55         if (size > 0) {
  56                 value = kzalloc(size, GFP_NOFS);
  57                 if (!value)
  58                         return ERR_PTR(-ENOMEM);
  59                 size = __btrfs_getxattr(inode, name, value, size);
  60                 if (size > 0) {
  61                         acl = posix_acl_from_xattr(value, size);
  62                         set_cached_acl(inode, type, acl);
  63                 }
  64                 kfree(value);
  65         } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  66                 /* FIXME, who returns -ENOENT?  I think nobody */
  67                 acl = NULL;
  68                 set_cached_acl(inode, type, acl);
  69         } else {
  70                 acl = ERR_PTR(-EIO);
  71         }
  72
  73         return acl;
  74 }
  75
  76 static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
  77                 void *value, size_t size, int type)
  78 {
  79         struct posix_acl *acl;
  80         int ret = 0;
  81
  82         acl = btrfs_get_acl(dentry->d_inode, type);
  83
  84         if (IS_ERR(acl))
  85                 return PTR_ERR(acl);
  86         if (acl == NULL)
  87                 return -ENODATA;
  88         ret = posix_acl_to_xattr(acl, value, size);
  89         posix_acl_release(acl);
  90
  91         return ret;
  92 }
  93
  94 /*
  95  * Needs to be called with fs_mutex held
  96  */
  97 static int btrfs_set_acl(struct btrfs_trans_handle *trans,
  98                          struct inode *inode, struct posix_acl *acl, int type)
  99 {
 100         int ret, size = 0;
 101         const char *name;
 102         char *value = NULL;
 103         mode_t mode;
 104
 105         if (acl) {
 106                 ret = posix_acl_valid(acl);
 107                 if (ret < 0)
 108                         return ret;
 109                 ret = 0;
 110         }
 111
 112         switch (type) {
 113         case ACL_TYPE_ACCESS:
 114                 mode = inode->i_mode;
 115                 name = POSIX_ACL_XATTR_ACCESS;
 116                 if (acl) {
 117                         ret = posix_acl_equiv_mode(acl, &mode);
 118                         if (ret < 0)
 119                                 return ret;
 120                         inode->i_mode = mode;
 121                 }
 122                 ret = 0;
 123                 break;
 124         case ACL_TYPE_DEFAULT:
 125                 if (!S_ISDIR(inode->i_mode))
 126                         return acl ? -EINVAL : 0;
 127                 name = POSIX_ACL_XATTR_DEFAULT;
 128                 break;
 129         default:
 130                 return -EINVAL;
 131         }
 132
 133         if (acl) {
 134                 size = posix_acl_xattr_size(acl->a_count);
 135                 value = kmalloc(size, GFP_NOFS);
 136                 if (!value) {
 137                         ret = -ENOMEM;
 138                         goto out;
 139                 }
 140
 141                 ret = posix_acl_to_xattr(acl, value, size);
 142                 if (ret < 0)
 143                         goto out;
 144         }
 145
 146         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 147 out:
 148         kfree(value);
 149
 150         if (!ret)
 151                 set_cached_acl(inode, type, acl);
 152
 153         return ret;
 154 }
 155
 156 static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 157                 const void *value, size_t size, int flags, int type)
 158 {
 159         int ret;
 160         struct posix_acl *acl = NULL;
 161
 162         if (!is_owner_or_cap(dentry->d_inode))
 163                 return -EPERM;
 164
 165         if (value) {
 166                 acl = posix_acl_from_xattr(value, size);
 167                 if (acl == NULL) {
 168                         value = NULL;
 169                         size = 0;
 170                 } else if (IS_ERR(acl)) {
 171                         return PTR_ERR(acl);
 172                 }
 173         }
 174
 175         ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
 176
 177         posix_acl_release(acl);
 178
 179         return ret;
 180 }
 181
 182 int btrfs_check_acl(struct inode *inode, int mask)
 183 {
 184         struct posix_acl *acl;
 185         int error = -EAGAIN;
 186
 187         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 188
 189         if (IS_ERR(acl))
 190                 return PTR_ERR(acl);
 191         if (acl) {
 192                 error = posix_acl_permission(inode, acl, mask);
 193                 posix_acl_release(acl);
 194         }
 195
 196         return error;
 197 }
 198
 199 /*
 200  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 201  * stuff has been fixed to work with that.  If the locking stuff changes, we
 202  * need to re-evaluate the acl locking stuff.
 203  */
 204 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 205                    struct inode *inode, struct inode *dir)
 206 {
 207         struct posix_acl *acl = NULL;
 208         int ret = 0;
 209
 210         /* this happens with subvols */
 211         if (!dir)
 212                 return 0;
 213
 214         if (!S_ISLNK(inode->i_mode)) {
 215                 if (IS_POSIXACL(dir)) {
 216                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 217                         if (IS_ERR(acl))
 218                                 return PTR_ERR(acl);
 219                 }
 220
 221                 if (!acl)
 222                         inode->i_mode &= ~current_umask();
 223         }
 224
 225         if (IS_POSIXACL(dir) && acl) {
 226                 struct posix_acl *clone;
 227                 mode_t mode;
 228
 229                 if (S_ISDIR(inode->i_mode)) {
 230                         ret = btrfs_set_acl(trans, inode, acl,
 231                                             ACL_TYPE_DEFAULT);
 232                         if (ret)
 233                                 goto failed;
 234                 }
 235                 clone = posix_acl_clone(acl, GFP_NOFS);
 236                 ret = -ENOMEM;
 237                 if (!clone)
 238                         goto failed;
 239
 240                 mode = inode->i_mode;
 241                 ret = posix_acl_create_masq(clone, &mode);
 242                 if (ret >= 0) {
 243                         inode->i_mode = mode;
 244                         if (ret > 0) {
 245                                 /* we need an acl */
 246                                 ret = btrfs_set_acl(trans, inode, clone,
 247                                                     ACL_TYPE_ACCESS);
 248                         }
 249                 }
 250                 posix_acl_release(clone);
 251         }
 252 failed:
 253         posix_acl_release(acl);
 254
 255         return ret;
 256 }
 257
 258 int btrfs_acl_chmod(struct inode *inode)
 259 {
 260         struct posix_acl *acl, *clone;
 261         int ret = 0;
 262
 263         if (S_ISLNK(inode->i_mode))
 264                 return -EOPNOTSUPP;
 265
 266         if (!IS_POSIXACL(inode))
 267                 return 0;
 268
 269         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 270         if (IS_ERR(acl) || !acl)
 271                 return PTR_ERR(acl);
 272
 273         clone = posix_acl_clone(acl, GFP_KERNEL);
 274         posix_acl_release(acl);
 275         if (!clone)
 276                 return -ENOMEM;
 277
 278         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 279         if (!ret)
 280                 ret = btrfs_set_acl(NULL, inode, clone, ACL_TYPE_ACCESS);
 281
 282         posix_acl_release(clone);
 283
 284         return ret;
 285 }
 286
 287 struct xattr_handler btrfs_xattr_acl_default_handler = {
 288         .prefix = POSIX_ACL_XATTR_DEFAULT,
 289         .flags  = ACL_TYPE_DEFAULT,
 290         .get    = btrfs_xattr_acl_get,
 291         .set    = btrfs_xattr_acl_set,
 292 };
 293
 294 struct xattr_handler btrfs_xattr_acl_access_handler = {
 295         .prefix = POSIX_ACL_XATTR_ACCESS,
 296         .flags  = ACL_TYPE_ACCESS,
 297         .get    = btrfs_xattr_acl_get,
 298         .set    = btrfs_xattr_acl_set,
 299 };
 300
 301 #else /* CONFIG_BTRFS_FS_POSIX_ACL */
 302
 303 int btrfs_acl_chmod(struct inode *inode)
 304 {
 305         return 0;
 306 }
 307
 308 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 309                    struct inode *inode, struct inode *dir)
 310 {
 311         return 0;
 312 }
 313
 314 #endif /* CONFIG_BTRFS_FS_POSIX_ACL */