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 inode *inode, struct posix_acl *acl, int type)
  98 {
  99         int ret, size = 0;
 100         const char *name;
 101         char *value = NULL;
 102         mode_t mode;
 103
 104         if (acl) {
 105                 ret = posix_acl_valid(acl);
 106                 if (ret < 0)
 107                         return ret;
 108                 ret = 0;
 109         }
 110
 111         switch (type) {
 112         case ACL_TYPE_ACCESS:
 113                 mode = inode->i_mode;
 114                 ret = posix_acl_equiv_mode(acl, &mode);
 115                 if (ret < 0)
 116                         return ret;
 117                 ret = 0;
 118                 inode->i_mode = mode;
 119                 name = POSIX_ACL_XATTR_ACCESS;
 120                 break;
 121         case ACL_TYPE_DEFAULT:
 122                 if (!S_ISDIR(inode->i_mode))
 123                         return acl ? -EINVAL : 0;
 124                 name = POSIX_ACL_XATTR_DEFAULT;
 125                 break;
 126         default:
 127                 return -EINVAL;
 128         }
 129
 130         if (acl) {
 131                 size = posix_acl_xattr_size(acl->a_count);
 132                 value = kmalloc(size, GFP_NOFS);
 133                 if (!value) {
 134                         ret = -ENOMEM;
 135                         goto out;
 136                 }
 137
 138                 ret = posix_acl_to_xattr(acl, value, size);
 139                 if (ret < 0)
 140                         goto out;
 141         }
 142
 143         ret = __btrfs_setxattr(inode, name, value, size, 0);
 144
 145 out:
 146         kfree(value);
 147
 148         if (!ret)
 149                 set_cached_acl(inode, type, acl);
 150
 151         return ret;
 152 }
 153
 154 static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 155                 const void *value, size_t size, int flags, int type)
 156 {
 157         int ret = 0;
 158         struct posix_acl *acl = NULL;
 159
 160         if (value) {
 161                 acl = posix_acl_from_xattr(value, size);
 162                 if (acl == NULL) {
 163                         value = NULL;
 164                         size = 0;
 165                 } else if (IS_ERR(acl)) {
 166                         return PTR_ERR(acl);
 167                 }
 168         }
 169
 170         ret = btrfs_set_acl(dentry->d_inode, acl, type);
 171
 172         posix_acl_release(acl);
 173
 174         return ret;
 175 }
 176
 177 int btrfs_check_acl(struct inode *inode, int mask)
 178 {
 179         struct posix_acl *acl;
 180         int error = -EAGAIN;
 181
 182         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 183
 184         if (IS_ERR(acl))
 185                 return PTR_ERR(acl);
 186         if (acl) {
 187                 error = posix_acl_permission(inode, acl, mask);
 188                 posix_acl_release(acl);
 189         }
 190
 191         return error;
 192 }
 193
 194 /*
 195  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 196  * stuff has been fixed to work with that.  If the locking stuff changes, we
 197  * need to re-evaluate the acl locking stuff.
 198  */
 199 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 200 {
 201         struct posix_acl *acl = NULL;
 202         int ret = 0;
 203
 204         /* this happens with subvols */
 205         if (!dir)
 206                 return 0;
 207
 208         if (!S_ISLNK(inode->i_mode)) {
 209                 if (IS_POSIXACL(dir)) {
 210                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 211                         if (IS_ERR(acl))
 212                                 return PTR_ERR(acl);
 213                 }
 214
 215                 if (!acl)
 216                         inode->i_mode &= ~current_umask();
 217         }
 218
 219         if (IS_POSIXACL(dir) && acl) {
 220                 struct posix_acl *clone;
 221                 mode_t mode;
 222
 223                 if (S_ISDIR(inode->i_mode)) {
 224                         ret = btrfs_set_acl(inode, acl, ACL_TYPE_DEFAULT);
 225                         if (ret)
 226                                 goto failed;
 227                 }
 228                 clone = posix_acl_clone(acl, GFP_NOFS);
 229                 ret = -ENOMEM;
 230                 if (!clone)
 231                         goto failed;
 232
 233                 mode = inode->i_mode;
 234                 ret = posix_acl_create_masq(clone, &mode);
 235                 if (ret >= 0) {
 236                         inode->i_mode = mode;
 237                         if (ret > 0) {
 238                                 /* we need an acl */
 239                                 ret = btrfs_set_acl(inode, clone,
 240                                                     ACL_TYPE_ACCESS);
 241                         }
 242                 }
 243         }
 244 failed:
 245         posix_acl_release(acl);
 246
 247         return ret;
 248 }
 249
 250 int btrfs_acl_chmod(struct inode *inode)
 251 {
 252         struct posix_acl *acl, *clone;
 253         int ret = 0;
 254
 255         if (S_ISLNK(inode->i_mode))
 256                 return -EOPNOTSUPP;
 257
 258         if (!IS_POSIXACL(inode))
 259                 return 0;
 260
 261         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 262         if (IS_ERR(acl) || !acl)
 263                 return PTR_ERR(acl);
 264
 265         clone = posix_acl_clone(acl, GFP_KERNEL);
 266         posix_acl_release(acl);
 267         if (!clone)
 268                 return -ENOMEM;
 269
 270         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 271         if (!ret)
 272                 ret = btrfs_set_acl(inode, clone, ACL_TYPE_ACCESS);
 273
 274         posix_acl_release(clone);
 275
 276         return ret;
 277 }
 278
 279 struct xattr_handler btrfs_xattr_acl_default_handler = {
 280         .prefix = POSIX_ACL_XATTR_DEFAULT,
 281         .flags  = ACL_TYPE_DEFAULT,
 282         .get    = btrfs_xattr_acl_get,
 283         .set    = btrfs_xattr_acl_set,
 284 };
 285
 286 struct xattr_handler btrfs_xattr_acl_access_handler = {
 287         .prefix = POSIX_ACL_XATTR_ACCESS,
 288         .flags  = ACL_TYPE_ACCESS,
 289         .get    = btrfs_xattr_acl_get,
 290         .set    = btrfs_xattr_acl_set,
 291 };
 292
 293 #else /* CONFIG_BTRFS_FS_POSIX_ACL */
 294
 295 int btrfs_acl_chmod(struct inode *inode)
 296 {
 297         return 0;
 298 }
 299
 300 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 301 {
 302         return 0;
 303 }
 304
 305 #endif /* CONFIG_BTRFS_FS_POSIX_ACL */