- 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 <linux/posix_acl_xattr.h>
#include "ctree.h"
#include "btrfs_inode.h"
#include "transaction.h"
#include "xattr.h"
#include "disk-io.h"
#include "props.h"
#include "locking.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 = NULL;
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;
path->skip_release_on_error = 1;
if (!value) {
di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode),
name, name_len, -1);
if (!di && (flags & XATTR_REPLACE))
ret = -ENODATA;
else if (IS_ERR(di))
ret = PTR_ERR(di);
else if (di)
ret = btrfs_delete_one_dir_name(trans, root, path, di);
goto out;
}
/*
* For a replace we can't just do the insert blindly.
* Do a lookup first (read-only btrfs_search_slot), and return if xattr
* doesn't exist. If it exists, fall down below to the insert/replace
* path - we can't race with a concurrent xattr delete, because the VFS
* locks the inode's i_mutex before calling setxattr or removexattr.
*/
if (flags & XATTR_REPLACE) {
ASSERT(mutex_is_locked(&inode->i_mutex));
di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode),
name, name_len, 0);
if (!di)
ret = -ENODATA;
else if (IS_ERR(di))
ret = PTR_ERR(di);
if (ret)
goto out;
btrfs_release_path(path);
di = NULL;
}
ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode),
name, name_len, value, size);
if (ret == -EOVERFLOW) {
/*
* We have an existing item in a leaf, split_leaf couldn't
* expand it. That item might have or not a dir_item that
* matches our target xattr, so lets check.
*/
ret = 0;
btrfs_assert_tree_locked(path->nodes[0]);
di = btrfs_match_dir_item_name(root, path, name, name_len);
if (!di && !(flags & XATTR_REPLACE)) {
ret = -ENOSPC;
goto out;
}
} else if (ret == -EEXIST) {
ret = 0;
di = btrfs_match_dir_item_name(root, path, name, name_len);
ASSERT(di); /* logic error */
} else if (ret) {
goto out;
}
if (di && (flags & XATTR_CREATE)) {
ret = -EEXIST;
goto out;
}
if (di) {
/*
* We're doing a replace, and it must be atomic, that is, at
* any point in time we have either the old or the new xattr
* value in the tree. We don't want readers (getxattr and
* listxattrs) to miss a value, this is specially important
* for ACLs.
*/
const int slot = path->slots[0];
struct extent_buffer *leaf = path->nodes[0];
const u16 old_data_len = btrfs_dir_data_len(leaf, di);
const u32 item_size = btrfs_item_size_nr(leaf, slot);
const u32 data_size = sizeof(*di) + name_len + size;
struct btrfs_item *item;
unsigned long data_ptr;
char *ptr;
if (size > old_data_len) {
if (btrfs_leaf_free_space(root, leaf) <
(size - old_data_len)) {
ret = -ENOSPC;
goto out;
}
}
if (old_data_len + name_len + sizeof(*di) == item_size) {
/* No other xattrs packed in the same leaf item. */
if (size > old_data_len)
btrfs_extend_item(root, path,
size - old_data_len);
else if (size < old_data_len)
btrfs_truncate_item(root, path, data_size, 1);
} else {
/* There are other xattrs packed in the same item. */
ret = btrfs_delete_one_dir_name(trans, root, path, di);
if (ret)
goto out;
btrfs_extend_item(root, path, data_size);
}
item = btrfs_item_nr(slot);
ptr = btrfs_item_ptr(leaf, slot, char);
ptr += btrfs_item_size(leaf, item) - data_size;
di = (struct btrfs_dir_item *)ptr;
btrfs_set_dir_data_len(leaf, di, size);
data_ptr = ((unsigned long)(di + 1)) + name_len;
write_extent_buffer(leaf, value, data_ptr, size);
btrfs_mark_buffer_dirty(leaf);
} else {
/*
* Insert, and we had space for the xattr, so path->slots[0] is
* where our xattr dir_item is and btrfs_insert_xattr_item()
* filled it.
*/
}
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 = d_inode(dentry);
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);
key.type = 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 (found_key.type > BTRFS_XATTR_ITEM_KEY)
break;
if (found_key.type < BTRFS_XATTR_ITEM_KEY)
goto next;
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
&posix_acl_access_xattr_handler,
&posix_acl_default_xattr_handler,
#endif
NULL,
};
/*
* Check if the attribute is in a supported namespace.
*
* This is applied after the check for the synthetic attributes in the system
* namespace.
*/
static int btrfs_is_valid_xattr(const char *name)
{
int len = strlen(name);
int prefixlen = 0;
if (!strncmp(name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN))
prefixlen = XATTR_SECURITY_PREFIX_LEN;
else if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
prefixlen = XATTR_SYSTEM_PREFIX_LEN;
else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
prefixlen = XATTR_TRUSTED_PREFIX_LEN;
else if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
prefixlen = XATTR_USER_PREFIX_LEN;
else if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
prefixlen = XATTR_BTRFS_PREFIX_LEN;
else
return -EOPNOTSUPP;
/*
* The name cannot consist of just prefix
*/
if (len <= prefixlen)
return -EINVAL;
return 0;
}
ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
int ret;
/*
* 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);
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
return __btrfs_getxattr(d_inode(dentry), 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(d_inode(dentry))->root;
int ret;
/*
* 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);
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
return btrfs_set_prop(d_inode(dentry), name,
value, size, flags);
if (size == 0)
value = ""; /* empty EA, do not remove */
return __btrfs_setxattr(NULL, d_inode(dentry), name, value, size,
flags);
}
int btrfs_removexattr(struct dentry *dentry, const char *name)
{
struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
int ret;
/*
* 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);
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
return btrfs_set_prop(d_inode(dentry), name,
NULL, 0, XATTR_REPLACE);
return __btrfs_setxattr(NULL, d_inode(dentry), 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);
}