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                 if (acl) {
  82                         ret = posix_acl_equiv_mode(acl, &inode->i_mode);
  83                         if (ret < 0)
  84                                 return ret;
  85                         if (ret == 0)
  86                                 acl = NULL;
  87                 }
  88                 ret = 0;
  89                 break;
  90         case ACL_TYPE_DEFAULT:
  91                 if (!S_ISDIR(inode->i_mode))
  92                         return acl ? -EINVAL : 0;
  93                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  94                 break;
  95         default:
  96                 return -EINVAL;
  97         }
  98
  99         if (acl) {
 100                 size = posix_acl_xattr_size(acl->a_count);
 101                 value = kmalloc(size, GFP_KERNEL);
 102                 if (!value) {
 103                         ret = -ENOMEM;
 104                         goto out;
 105                 }
 106
 107                 ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 108                 if (ret < 0)
 109                         goto out;
 110         }
 111
 112         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 113 out:
 114         kfree(value);
 115
 116         if (!ret)
 117                 set_cached_acl(inode, type, acl);
 118
 119         return ret;
 120 }
 121
 122 int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 123 {
 124         return __btrfs_set_acl(NULL, inode, acl, type);
 125 }
 126
 127 /*
 128  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 129  * stuff has been fixed to work with that.  If the locking stuff changes, we
 130  * need to re-evaluate the acl locking stuff.
 131  */
 132 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 133                    struct inode *inode, struct inode *dir)
 134 {
 135         struct posix_acl *default_acl, *acl;
 136         int ret = 0;
 137
 138         /* this happens with subvols */
 139         if (!dir)
 140                 return 0;
 141
 142         ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 143         if (ret)
 144                 return ret;
 145
 146         if (default_acl) {
 147                 ret = __btrfs_set_acl(trans, inode, default_acl,
 148                                       ACL_TYPE_DEFAULT);
 149                 posix_acl_release(default_acl);
 150         }
 151
 152         if (acl) {
 153                 if (!ret)
 154                         ret = __btrfs_set_acl(trans, inode, acl,
 155                                               ACL_TYPE_ACCESS);
 156                 posix_acl_release(acl);
 157         }
 158
 159         if (!default_acl && !acl)
 160                 cache_no_acl(inode);
 161         return ret;
 162 }