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