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