- 根目录:
- fs
- btrfs
- xattr.c
/*
* Copyright (C) 2007 Red Hat. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rwsem.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include "ctree.h"
#include "btrfs_inode.h"
#include "transaction.h"
#include "xattr.h"
#include "disk-io.h"
ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct btrfs_dir_item *di;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_path *path;
struct extent_buffer *leaf;
int ret = 0;
unsigned long data_ptr;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
/* lookup the xattr by name */
di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name,
strlen(name), 0);
if (!di) {
ret = -ENODATA;
goto out;
} else if (IS_ERR(di)) {
ret = PTR_ERR(di);
goto out;
}
leaf = path->nodes[0];
/* if size is 0, that means we want the size of the attr */
if (!size) {
ret = btrfs_dir_data_len(leaf, di);
goto out;
}
/* now get the data out of our dir_item */
if (btrfs_dir_data_len(leaf, di) > size) {
ret = -ERANGE;
goto out;
}
/*
* The way things are packed into the leaf is like this
* |struct btrfs_dir_item|name|data|
* where name is the xattr name, so security.foo, and data is the
* content of the xattr. data_ptr points to the location in memory
* where the data starts in the in memory leaf
*/
data_ptr = (unsigned long)((char *)(di + 1) +
btrfs_dir_name_len(leaf, di));
read_extent_buffer(leaf, buffer, data_ptr,
btrfs_dir_data_len(leaf, di));
ret = btrfs_dir_data_len(leaf, di);
out:
btrfs_free_path(path);
return ret;
}
static int do_setxattr(struct btrfs_trans_handle *trans,
struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct btrfs_dir_item *di;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_path *path;
size_t name_len = strlen(name);
int ret = 0;
if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
return -ENOSPC;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
if (flags & XATTR_REPLACE) {
di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name,
name_len, -1);
if (IS_ERR(di)) {
ret = PTR_ERR(di);
goto out;
} else if (!di) {
ret = -ENODATA;
goto out;
}
ret = btrfs_delete_one_dir_name(trans, root, path, di);
if (ret)
goto out;
btrfs_release_path(path);
/*
* remove the attribute
*/
if (!value)
goto out;
} else {
di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode),
name, name_len, 0);
if (IS_ERR(di)) {
ret = PTR_ERR(di);
goto out;
}
if (!di && !value)
goto out;
btrfs_release_path(path);
}
again:
ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
name, name_len, value, size);
/*
* If we're setting an xattr to a new value but the new value is say
* exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting
* back from split_leaf. This is because it thinks we'll be extending
* the existing item size, but we're asking for enough space to add the
* item itself. So if we get EOVERFLOW just set ret to EEXIST and let
* the rest of the function figure it out.
*/
if (ret == -EOVERFLOW)
ret = -EEXIST;
if (ret == -EEXIST) {
if (flags & XATTR_CREATE)
goto out;
/*
* We can't use the path we already have since we won't have the
* proper locking for a delete, so release the path and
* re-lookup to delete the thing.
*/
btrfs_release_path(path);
di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
name, name_len, -1);
if (IS_ERR(di)) {
ret = PTR_ERR(di);
goto out;
} else if (!di) {
/* Shouldn't happen but just in case... */
btrfs_release_path(path);
goto again;
}
ret = btrfs_delete_one_dir_name(trans, root, path, di);
if (ret)
goto out;
/*
* We have a value to set, so go back and try to insert it now.
*/
if (value) {
btrfs_release_path(path);
goto again;
}
}
out:
btrfs_free_path(path);
return ret;
}
/*
* @value: "" makes the attribute to empty, NULL removes it
*/
int __btrfs_setxattr(struct btrfs_trans_handle *trans,
struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
int ret;
if (trans)
return do_setxattr(trans, inode, name, value, size, flags);
trans = btrfs_start_transaction(root, 2);
if (IS_ERR(trans))
return PTR_ERR(trans);
ret = do_setxattr(trans, inode, name, value, size, flags);
if (ret)
goto out;
inode_inc_iversion(inode);
inode->i_ctime = CURRENT_TIME;
set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
ret = btrfs_update_inode(trans, root, inode);
BUG_ON(ret);
out:
btrfs_end_transaction(trans, root);
return ret;
}
ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
struct btrfs_key key, found_key;
struct inode *inode = dentry->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_path *path;
struct extent_buffer *leaf;
struct btrfs_dir_item *di;
int ret = 0, slot;
size_t total_size = 0, size_left = size;
unsigned long name_ptr;
size_t name_len;
/*
* ok we want all objects associated with this id.
* NOTE: we set key.offset = 0; because we want to start with the
* first xattr that we find and walk forward
*/
key.objectid = btrfs_ino(inode);
btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
key.offset = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = 2;
/* search for our xattrs */
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
goto err;
while (1) {
leaf = path->nodes[0];
slot = path->slots[0];
/* this is where we start walking through the path */
if (slot >= btrfs_header_nritems(leaf)) {
/*
* if we've reached the last slot in this leaf we need
* to go to the next leaf and reset everything
*/
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto err;
else if (ret > 0)
break;
continue;
}
btrfs_item_key_to_cpu(leaf, &found_key, slot);
/* check to make sure this item is what we want */
if (found_key.objectid != key.objectid)
break;
if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
break;
di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
if (verify_dir_item(root, leaf, di))
goto next;
name_len = btrfs_dir_name_len(leaf, di);
total_size += name_len + 1;
/* we are just looking for how big our buffer needs to be */
if (!size)
goto next;
if (!buffer || (name_len + 1) > size_left) {
ret = -ERANGE;
goto err;
}
name_ptr = (unsigned long)(di + 1);
read_extent_buffer(leaf, buffer, name_ptr, name_len);
buffer[name_len] = '\0';
size_left -= name_len + 1;
buffer += name_len + 1;
next:
path->slots[0]++;
}
ret = total_size;
err:
btrfs_free_path(path);
return ret;
}
/*
* List of handlers for synthetic system.* attributes. All real ondisk
* attributes are handled directly.
*/
const struct xattr_handler *btrfs_xattr_handlers[] = {
#ifdef CONFIG_BTRFS_FS_POSIX_ACL
&btrfs_xattr_acl_access_handler,
&btrfs_xattr_acl_default_handler,
#endif
NULL,
};
/*
* Check if the attribute is in a supported namespace.
*
* This applied after the check for the synthetic attributes in the system
* namespace.
*/
static bool btrfs_is_valid_xattr(const char *name)
{
return !strncmp(name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN) ||
!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
}
ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_getxattr(dentry, name, buffer, size);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
}
int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags)
{
struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
/*
* The permission on security.* and system.* is not checked
* in permission().
*/
if (btrfs_root_readonly(root))
return -EROFS;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_setxattr(dentry, name, value, size, flags);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
if (size == 0)
value = ""; /* empty EA, do not remove */
return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
flags);
}
int btrfs_removexattr(struct dentry *dentry, const char *name)
{
struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
/*
* The permission on security.* and system.* is not checked
* in permission().
*/
if (btrfs_root_readonly(root))
return -EROFS;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_removexattr(dentry, name);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
XATTR_REPLACE);
}
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_NOFS);
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);
}