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 == -ENOENT || size == -ENODATA || size == 0) {
  59                 /* FIXME, who returns -ENOENT?  I think nobody */
  60                 acl = NULL;
  61         } else {
  62                 acl = ERR_PTR(-EIO);
  63         }
  64         kfree(value);
  65
  66         if (!IS_ERR(acl))
  67                 set_cached_acl(inode, type, acl);
  68
  69         return acl;
  70 }
  71
  72 /*
  73  * Needs to be called with fs_mutex held
  74  */
  75 static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
  76                          struct inode *inode, struct posix_acl *acl, int type)
  77 {
  78         int ret, size = 0;
  79         const char *name;
  80         char *value = NULL;
  81
  82         switch (type) {
  83         case ACL_TYPE_ACCESS:
  84                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  85                 if (acl) {
  86                         ret = posix_acl_equiv_mode(acl, &inode->i_mode);
  87                         if (ret < 0)
  88                                 return ret;
  89                         if (ret == 0)
  90                                 acl = NULL;
  91                 }
  92                 ret = 0;
  93                 break;
  94         case ACL_TYPE_DEFAULT:
  95                 if (!S_ISDIR(inode->i_mode))
  96                         return acl ? -EINVAL : 0;
  97                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  98                 break;
  99         default:
 100                 return -EINVAL;
 101         }
 102
 103         if (acl) {
 104                 size = posix_acl_xattr_size(acl->a_count);
 105                 value = kmalloc(size, GFP_KERNEL);
 106                 if (!value) {
 107                         ret = -ENOMEM;
 108                         goto out;
 109                 }
 110
 111                 ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 112                 if (ret < 0)
 113                         goto out;
 114         }
 115
 116         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 117 out:
 118         kfree(value);
 119
 120         if (!ret)
 121                 set_cached_acl(inode, type, acl);
 122
 123         return ret;
 124 }
 125
 126 int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 127 {
 128         return __btrfs_set_acl(NULL, inode, acl, type);
 129 }
 130
 131 /*
 132  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 133  * stuff has been fixed to work with that.  If the locking stuff changes, we
 134  * need to re-evaluate the acl locking stuff.
 135  */
 136 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 137                    struct inode *inode, struct inode *dir)
 138 {
 139         struct posix_acl *default_acl, *acl;
 140         int ret = 0;
 141
 142         /* this happens with subvols */
 143         if (!dir)
 144                 return 0;
 145
 146         ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 147         if (ret)
 148                 return ret;
 149
 150         if (default_acl) {
 151                 ret = __btrfs_set_acl(trans, inode, default_acl,
 152                                       ACL_TYPE_DEFAULT);
 153                 posix_acl_release(default_acl);
 154         }
 155
 156         if (acl) {
 157                 if (!ret)
 158                         ret = __btrfs_set_acl(trans, inode, acl,
 159                                               ACL_TYPE_ACCESS);
 160                 posix_acl_release(acl);
 161         }
 162
 163         if (!default_acl && !acl)
 164                 cache_no_acl(inode);
 165         return ret;
 166 }