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 = POSIX_ACL_XATTR_ACCESS;
  41                 break;
  42         case ACL_TYPE_DEFAULT:
  43                 name = POSIX_ACL_XATTR_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_NOFS);
  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         if (acl) {
  83                 ret = posix_acl_valid(acl);
  84                 if (ret < 0)
  85                         return ret;
  86                 ret = 0;
  87         }
  88
  89         switch (type) {
  90         case ACL_TYPE_ACCESS:
  91                 name = POSIX_ACL_XATTR_ACCESS;
  92                 if (acl) {
  93                         ret = posix_acl_equiv_mode(acl, &inode->i_mode);
  94                         if (ret < 0)
  95                                 return ret;
  96                         if (ret == 0)
  97                                 acl = NULL;
  98                 }
  99                 ret = 0;
 100                 break;
 101         case ACL_TYPE_DEFAULT:
 102                 if (!S_ISDIR(inode->i_mode))
 103                         return acl ? -EINVAL : 0;
 104                 name = POSIX_ACL_XATTR_DEFAULT;
 105                 break;
 106         default:
 107                 return -EINVAL;
 108         }
 109
 110         if (acl) {
 111                 size = posix_acl_xattr_size(acl->a_count);
 112                 value = kmalloc(size, GFP_NOFS);
 113                 if (!value) {
 114                         ret = -ENOMEM;
 115                         goto out;
 116                 }
 117
 118                 ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 119                 if (ret < 0)
 120                         goto out;
 121         }
 122
 123         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 124 out:
 125         kfree(value);
 126
 127         if (!ret)
 128                 set_cached_acl(inode, type, acl);
 129
 130         return ret;
 131 }
 132
 133 int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 134 {
 135         return __btrfs_set_acl(NULL, inode, acl, type);
 136 }
 137
 138 /*
 139  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 140  * stuff has been fixed to work with that.  If the locking stuff changes, we
 141  * need to re-evaluate the acl locking stuff.
 142  */
 143 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 144                    struct inode *inode, struct inode *dir)
 145 {
 146         struct posix_acl *default_acl, *acl;
 147         int ret = 0;
 148
 149         /* this happens with subvols */
 150         if (!dir)
 151                 return 0;
 152
 153         ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 154         if (ret)
 155                 return ret;
 156
 157         if (default_acl) {
 158                 ret = __btrfs_set_acl(trans, inode, default_acl,
 159                                       ACL_TYPE_DEFAULT);
 160                 posix_acl_release(default_acl);
 161         }
 162
 163         if (acl) {
 164                 if (!ret)
 165                         ret = __btrfs_set_acl(trans, inode, acl,
 166                                               ACL_TYPE_ACCESS);
 167                 posix_acl_release(acl);
 168         }
 169
 170         if (!default_acl && !acl)
 171                 cache_no_acl(inode);
 172         return ret;
 173 }