- 根目录:
- fs
- squashfs
- xattr.c
/*
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2010
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2,
* or (at your option) any later version.
*
* 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* xattr.c
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/xattr.h>
#include <linux/slab.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
static const struct xattr_handler *squashfs_xattr_handler(int);
ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
size_t buffer_size)
{
struct inode *inode = d->d_inode;
struct super_block *sb = inode->i_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
+ msblk->xattr_table;
int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
int count = squashfs_i(inode)->xattr_count;
size_t rest = buffer_size;
int err;
/* check that the file system has xattrs */
if (msblk->xattr_id_table == NULL)
return -EOPNOTSUPP;
/* loop reading each xattr name */
while (count--) {
struct squashfs_xattr_entry entry;
struct squashfs_xattr_val val;
const struct xattr_handler *handler;
int name_size, prefix_size = 0;
err = squashfs_read_metadata(sb, &entry, &start, &offset,
sizeof(entry));
if (err < 0)
goto failed;
name_size = le16_to_cpu(entry.size);
handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
if (handler)
prefix_size = handler->list(d, buffer, rest, NULL,
name_size, handler->flags);
if (prefix_size) {
if (buffer) {
if (prefix_size + name_size + 1 > rest) {
err = -ERANGE;
goto failed;
}
buffer += prefix_size;
}
err = squashfs_read_metadata(sb, buffer, &start,
&offset, name_size);
if (err < 0)
goto failed;
if (buffer) {
buffer[name_size] = '\0';
buffer += name_size + 1;
}
rest -= prefix_size + name_size + 1;
} else {
/* no handler or insuffficient privileges, so skip */
err = squashfs_read_metadata(sb, NULL, &start,
&offset, name_size);
if (err < 0)
goto failed;
}
/* skip remaining xattr entry */
err = squashfs_read_metadata(sb, &val, &start, &offset,
sizeof(val));
if (err < 0)
goto failed;
err = squashfs_read_metadata(sb, NULL, &start, &offset,
le32_to_cpu(val.vsize));
if (err < 0)
goto failed;
}
err = buffer_size - rest;
failed:
return err;
}
static int squashfs_xattr_get(struct inode *inode, int name_index,
const char *name, void *buffer, size_t buffer_size)
{
struct super_block *sb = inode->i_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
+ msblk->xattr_table;
int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
int count = squashfs_i(inode)->xattr_count;
int name_len = strlen(name);
int err, vsize;
char *target = kmalloc(name_len, GFP_KERNEL);
if (target == NULL)
return -ENOMEM;
/* loop reading each xattr name */
for (; count; count--) {
struct squashfs_xattr_entry entry;
struct squashfs_xattr_val val;
int type, prefix, name_size;
err = squashfs_read_metadata(sb, &entry, &start, &offset,
sizeof(entry));
if (err < 0)
goto failed;
name_size = le16_to_cpu(entry.size);
type = le16_to_cpu(entry.type);
prefix = type & SQUASHFS_XATTR_PREFIX_MASK;
if (prefix == name_index && name_size == name_len)
err = squashfs_read_metadata(sb, target, &start,
&offset, name_size);
else
err = squashfs_read_metadata(sb, NULL, &start,
&offset, name_size);
if (err < 0)
goto failed;
if (prefix == name_index && name_size == name_len &&
strncmp(target, name, name_size) == 0) {
/* found xattr */
if (type & SQUASHFS_XATTR_VALUE_OOL) {
__le64 xattr_val;
u64 xattr;
/* val is a reference to the real location */
err = squashfs_read_metadata(sb, &val, &start,
&offset, sizeof(val));
if (err < 0)
goto failed;
err = squashfs_read_metadata(sb, &xattr_val,
&start, &offset, sizeof(xattr_val));
if (err < 0)
goto failed;
xattr = le64_to_cpu(xattr_val);
start = SQUASHFS_XATTR_BLK(xattr) +
msblk->xattr_table;
offset = SQUASHFS_XATTR_OFFSET(xattr);
}
/* read xattr value */
err = squashfs_read_metadata(sb, &val, &start, &offset,
sizeof(val));
if (err < 0)
goto failed;
vsize = le32_to_cpu(val.vsize);
if (buffer) {
if (vsize > buffer_size) {
err = -ERANGE;
goto failed;
}
err = squashfs_read_metadata(sb, buffer, &start,
&offset, vsize);
if (err < 0)
goto failed;
}
break;
}
/* no match, skip remaining xattr entry */
err = squashfs_read_metadata(sb, &val, &start, &offset,
sizeof(val));
if (err < 0)
goto failed;
err = squashfs_read_metadata(sb, NULL, &start, &offset,
le32_to_cpu(val.vsize));
if (err < 0)
goto failed;
}
err = count ? vsize : -ENODATA;
failed:
kfree(target);
return err;
}
/*
* User namespace support
*/
static size_t squashfs_user_list(struct dentry *d, char *list, size_t list_size,
const char *name, size_t name_len, int type)
{
if (list && XATTR_USER_PREFIX_LEN <= list_size)
memcpy(list, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
return XATTR_USER_PREFIX_LEN;
}
static int squashfs_user_get(struct dentry *d, const char *name, void *buffer,
size_t size, int type)
{
if (name[0] == '\0')
return -EINVAL;
return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_USER, name,
buffer, size);
}
static const struct xattr_handler squashfs_xattr_user_handler = {
.prefix = XATTR_USER_PREFIX,
.list = squashfs_user_list,
.get = squashfs_user_get
};
/*
* Trusted namespace support
*/
static size_t squashfs_trusted_list(struct dentry *d, char *list,
size_t list_size, const char *name, size_t name_len, int type)
{
if (!capable(CAP_SYS_ADMIN))
return 0;
if (list && XATTR_TRUSTED_PREFIX_LEN <= list_size)
memcpy(list, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
return XATTR_TRUSTED_PREFIX_LEN;
}
static int squashfs_trusted_get(struct dentry *d, const char *name,
void *buffer, size_t size, int type)
{
if (name[0] == '\0')
return -EINVAL;
return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_TRUSTED, name,
buffer, size);
}
static const struct xattr_handler squashfs_xattr_trusted_handler = {
.prefix = XATTR_TRUSTED_PREFIX,
.list = squashfs_trusted_list,
.get = squashfs_trusted_get
};
/*
* Security namespace support
*/
static size_t squashfs_security_list(struct dentry *d, char *list,
size_t list_size, const char *name, size_t name_len, int type)
{
if (list && XATTR_SECURITY_PREFIX_LEN <= list_size)
memcpy(list, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
return XATTR_SECURITY_PREFIX_LEN;
}
static int squashfs_security_get(struct dentry *d, const char *name,
void *buffer, size_t size, int type)
{
if (name[0] == '\0')
return -EINVAL;
return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_SECURITY, name,
buffer, size);
}
static const struct xattr_handler squashfs_xattr_security_handler = {
.prefix = XATTR_SECURITY_PREFIX,
.list = squashfs_security_list,
.get = squashfs_security_get
};
static const struct xattr_handler *squashfs_xattr_handler(int type)
{
if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
/* ignore unrecognised type */
return NULL;
switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
case SQUASHFS_XATTR_USER:
return &squashfs_xattr_user_handler;
case SQUASHFS_XATTR_TRUSTED:
return &squashfs_xattr_trusted_handler;
case SQUASHFS_XATTR_SECURITY:
return &squashfs_xattr_security_handler;
default:
/* ignore unrecognised type */
return NULL;
}
}
const struct xattr_handler *squashfs_xattr_handlers[] = {
&squashfs_xattr_user_handler,
&squashfs_xattr_trusted_handler,
&squashfs_xattr_security_handler,
NULL
};