![Eric Paris](/assets/img/avatar_default.png)
SELinux would like to implement a new labeling behavior of newly created inodes. We currently label new inodes based on the parent and the creating process. This new behavior would also take into account the name of the new object when deciding the new label. This is not the (supposed) full path, just the last component of the path. This is very useful because creating /etc/shadow is different than creating /etc/passwd but the kernel hooks are unable to differentiate these operations. We currently require that userspace realize it is doing some difficult operation like that and than userspace jumps through SELinux hoops to get things set up correctly. This patch does not implement new behavior, that is obviously contained in a seperate SELinux patch, but it does pass the needed name down to the correct LSM hook. If no such name exists it is fine to pass NULL. Signed-off-by: Eric Paris <eparis@redhat.com>
387 lines
9.6 KiB
C
387 lines
9.6 KiB
C
/*
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* Copyright (C) 2007 Red Hat. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/rwsem.h>
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#include <linux/xattr.h>
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#include <linux/security.h>
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#include "ctree.h"
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#include "btrfs_inode.h"
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#include "transaction.h"
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#include "xattr.h"
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#include "disk-io.h"
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ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
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void *buffer, size_t size)
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{
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struct btrfs_dir_item *di;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_path *path;
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struct extent_buffer *leaf;
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int ret = 0;
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unsigned long data_ptr;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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/* lookup the xattr by name */
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di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
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strlen(name), 0);
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if (!di) {
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ret = -ENODATA;
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goto out;
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} else if (IS_ERR(di)) {
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ret = PTR_ERR(di);
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goto out;
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}
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leaf = path->nodes[0];
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/* if size is 0, that means we want the size of the attr */
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if (!size) {
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ret = btrfs_dir_data_len(leaf, di);
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goto out;
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}
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/* now get the data out of our dir_item */
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if (btrfs_dir_data_len(leaf, di) > size) {
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ret = -ERANGE;
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goto out;
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}
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/*
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* The way things are packed into the leaf is like this
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* |struct btrfs_dir_item|name|data|
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* where name is the xattr name, so security.foo, and data is the
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* content of the xattr. data_ptr points to the location in memory
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* where the data starts in the in memory leaf
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*/
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data_ptr = (unsigned long)((char *)(di + 1) +
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btrfs_dir_name_len(leaf, di));
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read_extent_buffer(leaf, buffer, data_ptr,
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btrfs_dir_data_len(leaf, di));
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ret = btrfs_dir_data_len(leaf, di);
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out:
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btrfs_free_path(path);
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return ret;
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}
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static int do_setxattr(struct btrfs_trans_handle *trans,
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struct inode *inode, const char *name,
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const void *value, size_t size, int flags)
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{
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struct btrfs_dir_item *di;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_path *path;
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size_t name_len = strlen(name);
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int ret = 0;
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if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
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return -ENOSPC;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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/* first lets see if we already have this xattr */
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di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
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strlen(name), -1);
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if (IS_ERR(di)) {
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ret = PTR_ERR(di);
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goto out;
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}
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/* ok we already have this xattr, lets remove it */
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if (di) {
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/* if we want create only exit */
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if (flags & XATTR_CREATE) {
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ret = -EEXIST;
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goto out;
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}
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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BUG_ON(ret);
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btrfs_release_path(root, path);
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/* if we don't have a value then we are removing the xattr */
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if (!value)
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goto out;
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} else {
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btrfs_release_path(root, path);
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if (flags & XATTR_REPLACE) {
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/* we couldn't find the attr to replace */
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ret = -ENODATA;
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goto out;
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}
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}
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/* ok we have to create a completely new xattr */
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ret = btrfs_insert_xattr_item(trans, root, path, inode->i_ino,
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name, name_len, value, size);
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BUG_ON(ret);
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out:
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btrfs_free_path(path);
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return ret;
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}
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int __btrfs_setxattr(struct btrfs_trans_handle *trans,
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struct inode *inode, const char *name,
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const void *value, size_t size, int flags)
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{
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struct btrfs_root *root = BTRFS_I(inode)->root;
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int ret;
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if (trans)
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return do_setxattr(trans, inode, name, value, size, flags);
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trans = btrfs_start_transaction(root, 2);
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if (IS_ERR(trans))
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return PTR_ERR(trans);
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btrfs_set_trans_block_group(trans, inode);
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ret = do_setxattr(trans, inode, name, value, size, flags);
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if (ret)
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goto out;
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inode->i_ctime = CURRENT_TIME;
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ret = btrfs_update_inode(trans, root, inode);
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BUG_ON(ret);
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out:
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btrfs_end_transaction_throttle(trans, root);
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return ret;
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}
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ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
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{
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struct btrfs_key key, found_key;
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struct inode *inode = dentry->d_inode;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_path *path;
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struct extent_buffer *leaf;
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struct btrfs_dir_item *di;
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int ret = 0, slot, advance;
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size_t total_size = 0, size_left = size;
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unsigned long name_ptr;
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size_t name_len;
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u32 nritems;
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/*
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* ok we want all objects associated with this id.
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* NOTE: we set key.offset = 0; because we want to start with the
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* first xattr that we find and walk forward
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*/
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key.objectid = inode->i_ino;
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btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
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key.offset = 0;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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path->reada = 2;
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/* search for our xattrs */
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0)
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goto err;
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advance = 0;
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while (1) {
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leaf = path->nodes[0];
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nritems = btrfs_header_nritems(leaf);
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slot = path->slots[0];
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/* this is where we start walking through the path */
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if (advance || slot >= nritems) {
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/*
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* if we've reached the last slot in this leaf we need
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* to go to the next leaf and reset everything
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*/
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if (slot >= nritems-1) {
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ret = btrfs_next_leaf(root, path);
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if (ret)
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break;
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leaf = path->nodes[0];
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nritems = btrfs_header_nritems(leaf);
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slot = path->slots[0];
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} else {
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/*
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* just walking through the slots on this leaf
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*/
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slot++;
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path->slots[0]++;
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}
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}
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advance = 1;
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btrfs_item_key_to_cpu(leaf, &found_key, slot);
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/* check to make sure this item is what we want */
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if (found_key.objectid != key.objectid)
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break;
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if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
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break;
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di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
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name_len = btrfs_dir_name_len(leaf, di);
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total_size += name_len + 1;
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/* we are just looking for how big our buffer needs to be */
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if (!size)
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continue;
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if (!buffer || (name_len + 1) > size_left) {
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ret = -ERANGE;
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goto err;
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}
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name_ptr = (unsigned long)(di + 1);
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read_extent_buffer(leaf, buffer, name_ptr, name_len);
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buffer[name_len] = '\0';
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size_left -= name_len + 1;
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buffer += name_len + 1;
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}
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ret = total_size;
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err:
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btrfs_free_path(path);
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return ret;
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}
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/*
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* List of handlers for synthetic system.* attributes. All real ondisk
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* attributes are handled directly.
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*/
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const struct xattr_handler *btrfs_xattr_handlers[] = {
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#ifdef CONFIG_BTRFS_FS_POSIX_ACL
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&btrfs_xattr_acl_access_handler,
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&btrfs_xattr_acl_default_handler,
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#endif
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NULL,
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};
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/*
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* Check if the attribute is in a supported namespace.
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*
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* This applied after the check for the synthetic attributes in the system
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* namespace.
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*/
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static bool btrfs_is_valid_xattr(const char *name)
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{
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return !strncmp(name, XATTR_SECURITY_PREFIX,
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XATTR_SECURITY_PREFIX_LEN) ||
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!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
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!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
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!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
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}
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ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
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void *buffer, size_t size)
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{
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/*
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* If this is a request for a synthetic attribute in the system.*
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* namespace use the generic infrastructure to resolve a handler
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* for it via sb->s_xattr.
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*/
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if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
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return generic_getxattr(dentry, name, buffer, size);
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if (!btrfs_is_valid_xattr(name))
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return -EOPNOTSUPP;
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return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
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}
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int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
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size_t size, int flags)
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{
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/*
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* If this is a request for a synthetic attribute in the system.*
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* namespace use the generic infrastructure to resolve a handler
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* for it via sb->s_xattr.
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*/
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if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
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return generic_setxattr(dentry, name, value, size, flags);
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if (!btrfs_is_valid_xattr(name))
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return -EOPNOTSUPP;
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if (size == 0)
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value = ""; /* empty EA, do not remove */
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return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
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flags);
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}
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int btrfs_removexattr(struct dentry *dentry, const char *name)
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{
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/*
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* If this is a request for a synthetic attribute in the system.*
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* namespace use the generic infrastructure to resolve a handler
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* for it via sb->s_xattr.
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*/
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if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
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return generic_removexattr(dentry, name);
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if (!btrfs_is_valid_xattr(name))
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return -EOPNOTSUPP;
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return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
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XATTR_REPLACE);
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}
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int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
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struct inode *inode, struct inode *dir,
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const struct qstr *qstr)
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{
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int err;
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size_t len;
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void *value;
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char *suffix;
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char *name;
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err = security_inode_init_security(inode, dir, qstr, &suffix, &value,
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&len);
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if (err) {
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if (err == -EOPNOTSUPP)
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return 0;
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return err;
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}
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name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
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GFP_NOFS);
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if (!name) {
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err = -ENOMEM;
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} else {
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strcpy(name, XATTR_SECURITY_PREFIX);
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strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
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err = __btrfs_setxattr(trans, inode, name, value, len, 0);
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kfree(name);
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}
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kfree(suffix);
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kfree(value);
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return err;
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}
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