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         switch (type) {
  39         case ACL_TYPE_ACCESS:
  40                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  41                 break;
  42         case ACL_TYPE_DEFAULT:
  43                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  44                 break;
  45         default:
  46                 BUG();
  47         }
  48
  49         size = __btrfs_getxattr(inode, name, "", 0);
  50         if (size > 0) {
  51                 value = kzalloc(size, GFP_KERNEL);
  52                 if (!value)
  53                         return ERR_PTR(-ENOMEM);
  54                 size = __btrfs_getxattr(inode, name, value, size);
  55         }
  56         if (size > 0) {
  57                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
  58         } else if (size == -ERANGE || size == -ENODATA || size == 0) {
  59                 acl = NULL;
  60         } else {
  61                 acl = ERR_PTR(-EIO);
  62         }
  63         kfree(value);
  64
  65         return acl;
  66 }
  67
  68 /*
  69  * Needs to be called with fs_mutex held
  70  */
  71 static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
  72                          struct inode *inode, struct posix_acl *acl, int type)
  73 {
  74         int ret, size = 0;
  75         const char *name;
  76         char *value = NULL;
  77
  78         switch (type) {
  79         case ACL_TYPE_ACCESS:
  80                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  81                 break;
  82         case ACL_TYPE_DEFAULT:
  83                 if (!S_ISDIR(inode->i_mode))
  84                         return acl ? -EINVAL : 0;
  85                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  86                 break;
  87         default:
  88                 return -EINVAL;
  89         }
  90
  91         if (acl) {
  92                 size = posix_acl_xattr_size(acl->a_count);
  93                 value = kmalloc(size, GFP_KERNEL);
  94                 if (!value) {
  95                         ret = -ENOMEM;
  96                         goto out;
  97                 }
  98
  99                 ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 100                 if (ret < 0)
 101                         goto out;
 102         }
 103
 104         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 105 out:
 106         kfree(value);
 107
 108         if (!ret)
 109                 set_cached_acl(inode, type, acl);
 110
 111         return ret;
 112 }
 113
 114 int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 115 {
 116         int ret;
 117         umode_t old_mode = inode->i_mode;
 118
 119         if (type == ACL_TYPE_ACCESS && acl) {
 120                 ret = posix_acl_update_mode(inode, &inode->i_mode, &acl);
 121                 if (ret)
 122                         return ret;
 123         }
 124         ret = __btrfs_set_acl(NULL, inode, acl, type);
 125         if (ret)
 126                 inode->i_mode = old_mode;
 127         return ret;
 128 }
 129
 130 /*
 131  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 132  * stuff has been fixed to work with that.  If the locking stuff changes, we
 133  * need to re-evaluate the acl locking stuff.
 134  */
 135 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 136                    struct inode *inode, struct inode *dir)
 137 {
 138         struct posix_acl *default_acl, *acl;
 139         int ret = 0;
 140
 141         /* this happens with subvols */
 142         if (!dir)
 143                 return 0;
 144
 145         ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 146         if (ret)
 147                 return ret;
 148
 149         if (default_acl) {
 150                 ret = __btrfs_set_acl(trans, inode, default_acl,
 151                                       ACL_TYPE_DEFAULT);
 152                 posix_acl_release(default_acl);
 153         }
 154
 155         if (acl) {
 156                 if (!ret)
 157                         ret = __btrfs_set_acl(trans, inode, acl,
 158                                               ACL_TYPE_ACCESS);
 159                 posix_acl_release(acl);
 160         }
 161
 162         if (!default_acl && !acl)
 163                 cache_no_acl(inode);
 164         return ret;
 165 }