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![Su Yue](/assets/img/avatar_default.png)
Originally, verify_dir_item verifies name_len of dir_item with fixed values but not item boundary. If corrupted name_len was not bigger than the fixed value, for example 255, the function will think the dir_item is fine. And then reading beyond boundary will cause crash. Example: 1. Corrupt one dir_item name_len to be 255. 2. Run 'ls -lar /mnt/test/ > /dev/null' dmesg: [ 48.451449] BTRFS info (device vdb1): disk space caching is enabled [ 48.451453] BTRFS info (device vdb1): has skinny extents [ 48.489420] general protection fault: 0000 [#1] SMP [ 48.489571] Modules linked in: ext4 jbd2 mbcache btrfs xor raid6_pq [ 48.489716] CPU: 1 PID: 2710 Comm: ls Not tainted 4.10.0-rc1 #5 [ 48.489853] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 [ 48.490008] task: ffff880035df1bc0 task.stack: ffffc90004800000 [ 48.490008] RIP: 0010:read_extent_buffer+0xd2/0x190 [btrfs] [ 48.490008] RSP: 0018:ffffc90004803d98 EFLAGS: 00010202 [ 48.490008] RAX: 000000000000001b RBX: 000000000000001b RCX: 0000000000000000 [ 48.490008] RDX: ffff880079dbf36c RSI: 0005080000000000 RDI: ffff880079dbf368 [ 48.490008] RBP: ffffc90004803dc8 R08: ffff880078e8cc48 R09: ffff880000000000 [ 48.490008] R10: 0000160000000000 R11: 0000000000001000 R12: ffff880079dbf288 [ 48.490008] R13: ffff880078e8ca88 R14: 0000000000000003 R15: ffffc90004803e20 [ 48.490008] FS: 00007fef50c60800(0000) GS:ffff88007d400000(0000) knlGS:0000000000000000 [ 48.490008] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 48.490008] CR2: 000055f335ac2ff8 CR3: 000000007356d000 CR4: 00000000001406e0 [ 48.490008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 48.490008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 48.490008] Call Trace: [ 48.490008] btrfs_real_readdir+0x3b7/0x4a0 [btrfs] [ 48.490008] iterate_dir+0x181/0x1b0 [ 48.490008] SyS_getdents+0xa7/0x150 [ 48.490008] ? fillonedir+0x150/0x150 [ 48.490008] entry_SYSCALL_64_fastpath+0x18/0xad [ 48.490008] RIP: 0033:0x7fef5032546b [ 48.490008] RSP: 002b:00007ffeafcdb830 EFLAGS: 00000206 ORIG_RAX: 000000000000004e [ 48.490008] RAX: ffffffffffffffda RBX: 00007fef5061db38 RCX: 00007fef5032546b [ 48.490008] RDX: 0000000000008000 RSI: 000055f335abaff0 RDI: 0000000000000003 [ 48.490008] RBP: 00007fef5061dae0 R08: 00007fef5061db48 R09: 0000000000000000 [ 48.490008] R10: 000055f335abafc0 R11: 0000000000000206 R12: 00007fef5061db38 [ 48.490008] R13: 0000000000008040 R14: 00007fef5061db38 R15: 000000000000270e [ 48.490008] RIP: read_extent_buffer+0xd2/0x190 [btrfs] RSP: ffffc90004803d98 [ 48.499455] ---[ end trace 321920d8e8339505 ]--- Fix it by adding a parameter @slot and check name_len with item boundary by calling btrfs_is_name_len_valid. Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com> rev Signed-off-by: David Sterba <dsterba@suse.com>
471 lines
12 KiB
C
471 lines
12 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 <linux/posix_acl_xattr.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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#include "props.h"
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#include "locking.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, btrfs_ino(BTRFS_I(inode)),
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name, 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 = NULL;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_fs_info *fs_info = root->fs_info;
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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->fs_info))
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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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path->skip_release_on_error = 1;
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if (!value) {
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di = btrfs_lookup_xattr(trans, root, path,
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btrfs_ino(BTRFS_I(inode)), name, name_len, -1);
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if (!di && (flags & XATTR_REPLACE))
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ret = -ENODATA;
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else if (IS_ERR(di))
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ret = PTR_ERR(di);
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else if (di)
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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goto out;
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}
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/*
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* For a replace we can't just do the insert blindly.
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* Do a lookup first (read-only btrfs_search_slot), and return if xattr
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* doesn't exist. If it exists, fall down below to the insert/replace
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* path - we can't race with a concurrent xattr delete, because the VFS
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* locks the inode's i_mutex before calling setxattr or removexattr.
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*/
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if (flags & XATTR_REPLACE) {
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ASSERT(inode_is_locked(inode));
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di = btrfs_lookup_xattr(NULL, root, path,
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btrfs_ino(BTRFS_I(inode)), name, name_len, 0);
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if (!di)
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ret = -ENODATA;
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else if (IS_ERR(di))
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ret = PTR_ERR(di);
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if (ret)
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goto out;
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btrfs_release_path(path);
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di = NULL;
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}
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ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)),
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name, name_len, value, size);
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if (ret == -EOVERFLOW) {
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/*
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* We have an existing item in a leaf, split_leaf couldn't
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* expand it. That item might have or not a dir_item that
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* matches our target xattr, so lets check.
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*/
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ret = 0;
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btrfs_assert_tree_locked(path->nodes[0]);
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di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
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if (!di && !(flags & XATTR_REPLACE)) {
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ret = -ENOSPC;
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goto out;
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}
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} else if (ret == -EEXIST) {
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ret = 0;
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di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
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ASSERT(di); /* logic error */
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} else if (ret) {
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goto out;
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}
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if (di && (flags & XATTR_CREATE)) {
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ret = -EEXIST;
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goto out;
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}
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if (di) {
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/*
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* We're doing a replace, and it must be atomic, that is, at
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* any point in time we have either the old or the new xattr
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* value in the tree. We don't want readers (getxattr and
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* listxattrs) to miss a value, this is specially important
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* for ACLs.
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*/
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const int slot = path->slots[0];
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struct extent_buffer *leaf = path->nodes[0];
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const u16 old_data_len = btrfs_dir_data_len(leaf, di);
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const u32 item_size = btrfs_item_size_nr(leaf, slot);
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const u32 data_size = sizeof(*di) + name_len + size;
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struct btrfs_item *item;
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unsigned long data_ptr;
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char *ptr;
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if (size > old_data_len) {
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if (btrfs_leaf_free_space(fs_info, leaf) <
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(size - old_data_len)) {
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ret = -ENOSPC;
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goto out;
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}
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}
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if (old_data_len + name_len + sizeof(*di) == item_size) {
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/* No other xattrs packed in the same leaf item. */
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if (size > old_data_len)
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btrfs_extend_item(fs_info, path,
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size - old_data_len);
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else if (size < old_data_len)
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btrfs_truncate_item(fs_info, path,
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data_size, 1);
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} else {
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/* There are other xattrs packed in the same item. */
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ret = btrfs_delete_one_dir_name(trans, root, path, di);
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if (ret)
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goto out;
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btrfs_extend_item(fs_info, path, data_size);
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}
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item = btrfs_item_nr(slot);
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ptr = btrfs_item_ptr(leaf, slot, char);
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ptr += btrfs_item_size(leaf, item) - data_size;
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di = (struct btrfs_dir_item *)ptr;
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btrfs_set_dir_data_len(leaf, di, size);
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data_ptr = ((unsigned long)(di + 1)) + name_len;
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write_extent_buffer(leaf, value, data_ptr, size);
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btrfs_mark_buffer_dirty(leaf);
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} else {
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/*
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* Insert, and we had space for the xattr, so path->slots[0] is
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* where our xattr dir_item is and btrfs_insert_xattr_item()
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* filled it.
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*/
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}
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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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/*
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* @value: "" makes the attribute to empty, NULL removes it
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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 (btrfs_root_readonly(root))
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return -EROFS;
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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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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_inc_iversion(inode);
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inode->i_ctime = current_time(inode);
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set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
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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(trans);
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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;
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struct inode *inode = d_inode(dentry);
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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struct btrfs_root *root = BTRFS_I(inode)->root;
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struct btrfs_path *path;
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int ret = 0;
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size_t total_size = 0, size_left = size;
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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 = btrfs_ino(BTRFS_I(inode));
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key.type = 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 = READA_FORWARD;
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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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while (1) {
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struct extent_buffer *leaf;
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int slot;
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struct btrfs_dir_item *di;
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struct btrfs_key found_key;
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u32 item_size;
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u32 cur;
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leaf = path->nodes[0];
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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 (slot >= btrfs_header_nritems(leaf)) {
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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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ret = btrfs_next_leaf(root, path);
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if (ret < 0)
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goto err;
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else if (ret > 0)
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break;
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continue;
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}
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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 (found_key.type > BTRFS_XATTR_ITEM_KEY)
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break;
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if (found_key.type < BTRFS_XATTR_ITEM_KEY)
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goto next_item;
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di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
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item_size = btrfs_item_size_nr(leaf, slot);
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cur = 0;
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while (cur < item_size) {
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u16 name_len = btrfs_dir_name_len(leaf, di);
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u16 data_len = btrfs_dir_data_len(leaf, di);
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u32 this_len = sizeof(*di) + name_len + data_len;
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unsigned long name_ptr = (unsigned long)(di + 1);
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if (verify_dir_item(fs_info, leaf, slot, di)) {
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ret = -EIO;
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goto err;
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}
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total_size += name_len + 1;
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/*
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* We are just looking for how big our buffer needs to
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* be.
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*/
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if (!size)
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goto next;
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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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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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next:
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cur += this_len;
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di = (struct btrfs_dir_item *)((char *)di + this_len);
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}
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next_item:
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path->slots[0]++;
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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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static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
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struct dentry *unused, struct inode *inode,
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const char *name, void *buffer, size_t size)
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{
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name = xattr_full_name(handler, name);
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return __btrfs_getxattr(inode, name, buffer, size);
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}
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static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
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struct dentry *unused, struct inode *inode,
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const char *name, const void *buffer,
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size_t size, int flags)
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{
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name = xattr_full_name(handler, name);
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return __btrfs_setxattr(NULL, inode, name, buffer, size, flags);
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}
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static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
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struct dentry *unused, struct inode *inode,
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const char *name, const void *value,
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size_t size, int flags)
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{
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name = xattr_full_name(handler, name);
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return btrfs_set_prop(inode, name, value, size, flags);
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}
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static const struct xattr_handler btrfs_security_xattr_handler = {
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.prefix = XATTR_SECURITY_PREFIX,
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.get = btrfs_xattr_handler_get,
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.set = btrfs_xattr_handler_set,
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};
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static const struct xattr_handler btrfs_trusted_xattr_handler = {
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.prefix = XATTR_TRUSTED_PREFIX,
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.get = btrfs_xattr_handler_get,
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.set = btrfs_xattr_handler_set,
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};
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static const struct xattr_handler btrfs_user_xattr_handler = {
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.prefix = XATTR_USER_PREFIX,
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.get = btrfs_xattr_handler_get,
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.set = btrfs_xattr_handler_set,
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};
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static const struct xattr_handler btrfs_btrfs_xattr_handler = {
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.prefix = XATTR_BTRFS_PREFIX,
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.get = btrfs_xattr_handler_get,
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.set = btrfs_xattr_handler_set_prop,
|
|
};
|
|
|
|
const struct xattr_handler *btrfs_xattr_handlers[] = {
|
|
&btrfs_security_xattr_handler,
|
|
#ifdef CONFIG_BTRFS_FS_POSIX_ACL
|
|
&posix_acl_access_xattr_handler,
|
|
&posix_acl_default_xattr_handler,
|
|
#endif
|
|
&btrfs_trusted_xattr_handler,
|
|
&btrfs_user_xattr_handler,
|
|
&btrfs_btrfs_xattr_handler,
|
|
NULL,
|
|
};
|
|
|
|
static int btrfs_initxattrs(struct inode *inode,
|
|
const struct xattr *xattr_array, void *fs_info)
|
|
{
|
|
const struct xattr *xattr;
|
|
struct btrfs_trans_handle *trans = fs_info;
|
|
char *name;
|
|
int err = 0;
|
|
|
|
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
|
|
name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
|
|
strlen(xattr->name) + 1, GFP_KERNEL);
|
|
if (!name) {
|
|
err = -ENOMEM;
|
|
break;
|
|
}
|
|
strcpy(name, XATTR_SECURITY_PREFIX);
|
|
strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
|
|
err = __btrfs_setxattr(trans, inode, name,
|
|
xattr->value, xattr->value_len, 0);
|
|
kfree(name);
|
|
if (err < 0)
|
|
break;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
|
|
struct inode *inode, struct inode *dir,
|
|
const struct qstr *qstr)
|
|
{
|
|
return security_inode_init_security(inode, dir, qstr,
|
|
&btrfs_initxattrs, trans);
|
|
}
|