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/sched/mm.h>
  26 #include <linux/slab.h>
  27
  28 #include "ctree.h"
  29 #include "btrfs_inode.h"
  30 #include "xattr.h"
  31
  32 struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  33 {
  34         int size;
  35         const char *name;
  36         char *value = NULL;
  37         struct posix_acl *acl;
  38
  39         switch (type) {
  40         case ACL_TYPE_ACCESS:
  41                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  42                 break;
  43         case ACL_TYPE_DEFAULT:
  44                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  45                 break;
  46         default:
  47                 BUG();
  48         }
  49
  50         size = __btrfs_getxattr(inode, name, "", 0);
  51         if (size > 0) {
  52                 value = kzalloc(size, GFP_KERNEL);
  53                 if (!value)
  54                         return ERR_PTR(-ENOMEM);
  55                 size = __btrfs_getxattr(inode, name, value, size);
  56         }
  57         if (size > 0) {
  58                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
  59         } else if (size == -ERANGE || size == -ENODATA || size == 0) {
  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                 break;
  83         case ACL_TYPE_DEFAULT:
  84                 if (!S_ISDIR(inode->i_mode))
  85                         return acl ? -EINVAL : 0;
  86                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  87                 break;
  88         default:
  89                 return -EINVAL;
  90         }
  91
  92         if (acl) {
  93                 unsigned int nofs_flag;
  94
  95                 size = posix_acl_xattr_size(acl->a_count);
  96                 /*
  97                  * We're holding a transaction handle, so use a NOFS memory
  98                  * allocation context to avoid deadlock if reclaim happens.
  99                  */
 100                 nofs_flag = memalloc_nofs_save();
 101                 value = kmalloc(size, GFP_KERNEL);
 102                 memalloc_nofs_restore(nofs_flag);
 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         int ret;
 126         umode_t old_mode = inode->i_mode;
 127
 128         if (type == ACL_TYPE_ACCESS && acl) {
 129                 ret = posix_acl_update_mode(inode, &inode->i_mode, &acl);
 130                 if (ret)
 131                         return ret;
 132         }
 133         ret = __btrfs_set_acl(NULL, inode, acl, type);
 134         if (ret)
 135                 inode->i_mode = old_mode;
 136         return ret;
 137 }
 138
 139 /*
 140  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 141  * stuff has been fixed to work with that.  If the locking stuff changes, we
 142  * need to re-evaluate the acl locking stuff.
 143  */
 144 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 145                    struct inode *inode, struct inode *dir)
 146 {
 147         struct posix_acl *default_acl, *acl;
 148         int ret = 0;
 149
 150         /* this happens with subvols */
 151         if (!dir)
 152                 return 0;
 153
 154         ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 155         if (ret)
 156                 return ret;
 157
 158         if (default_acl) {
 159                 ret = __btrfs_set_acl(trans, inode, default_acl,
 160                                       ACL_TYPE_DEFAULT);
 161                 posix_acl_release(default_acl);
 162         }
 163
 164         if (acl) {
 165                 if (!ret)
 166                         ret = __btrfs_set_acl(trans, inode, acl,
 167                                               ACL_TYPE_ACCESS);
 168                 posix_acl_release(acl);
 169         }
 170
 171         if (!default_acl && !acl)
 172                 cache_no_acl(inode);
 173         return ret;
 174 }