linux/fs/f2fs/xattr.h
Chao Yu dd6c89b5f2 f2fs: fix to do sanity check with inode.i_inline_xattr_size
As Paul Bandha reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=202709

When I run the poc on the mounted f2fs img I get a buffer overflow in
read_inline_xattr due to there being no sanity check on the value of
i_inline_xattr_size.

I created the img by just modifying the value of i_inline_xattr_size
in the inode:

i_name                        		[test1.txt]
i_ext: fofs:0 blkaddr:0 len:0
i_extra_isize                 		[0x      18 : 24]
i_inline_xattr_size           		[0x    ffff : 65535]
i_addr[ofs]                   		[0x       0 : 0]

mkdir /mnt/f2fs
mount ./f2fs1.img /mnt/f2fs
gcc poc.c -o poc
./poc

int main() {
	int y = syscall(SYS_listxattr, "/mnt/f2fs/test1.txt", NULL, 0);
	printf("ret %d", y);
	printf("errno: %d\n", errno);

}

 BUG: KASAN: slab-out-of-bounds in read_inline_xattr+0x18f/0x260
 Read of size 262140 at addr ffff88011035efd8 by task f2fs1poc/3263

 CPU: 0 PID: 3263 Comm: f2fs1poc Not tainted 4.18.0-custom #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
 Call Trace:
  dump_stack+0x71/0xab
  print_address_description+0x83/0x250
  kasan_report+0x213/0x350
  memcpy+0x1f/0x50
  read_inline_xattr+0x18f/0x260
  read_all_xattrs+0xba/0x190
  f2fs_listxattr+0x9d/0x3f0
  listxattr+0xb2/0xd0
  path_listxattr+0x93/0xe0
  do_syscall_64+0x9d/0x220
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Let's add sanity check for inode.i_inline_xattr_size during f2fs_iget()
to avoid this issue.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2019-03-12 19:02:26 -07:00

162 lines
4.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* fs/f2fs/xattr.h
*
* Copyright (c) 2012 Samsung Electronics Co., Ltd.
* http://www.samsung.com/
*
* Portions of this code from linux/fs/ext2/xattr.h
*
* On-disk format of extended attributes for the ext2 filesystem.
*
* (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
*/
#ifndef __F2FS_XATTR_H__
#define __F2FS_XATTR_H__
#include <linux/init.h>
#include <linux/xattr.h>
/* Magic value in attribute blocks */
#define F2FS_XATTR_MAGIC 0xF2F52011
/* Maximum number of references to one attribute block */
#define F2FS_XATTR_REFCOUNT_MAX 1024
/* Name indexes */
#define F2FS_SYSTEM_ADVISE_NAME "system.advise"
#define F2FS_XATTR_INDEX_USER 1
#define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS 2
#define F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
#define F2FS_XATTR_INDEX_TRUSTED 4
#define F2FS_XATTR_INDEX_LUSTRE 5
#define F2FS_XATTR_INDEX_SECURITY 6
#define F2FS_XATTR_INDEX_ADVISE 7
/* Should be same as EXT4_XATTR_INDEX_ENCRYPTION */
#define F2FS_XATTR_INDEX_ENCRYPTION 9
#define F2FS_XATTR_NAME_ENCRYPTION_CONTEXT "c"
struct f2fs_xattr_header {
__le32 h_magic; /* magic number for identification */
__le32 h_refcount; /* reference count */
__u32 h_reserved[4]; /* zero right now */
};
struct f2fs_xattr_entry {
__u8 e_name_index;
__u8 e_name_len;
__le16 e_value_size; /* size of attribute value */
char e_name[0]; /* attribute name */
};
#define XATTR_HDR(ptr) ((struct f2fs_xattr_header *)(ptr))
#define XATTR_ENTRY(ptr) ((struct f2fs_xattr_entry *)(ptr))
#define XATTR_FIRST_ENTRY(ptr) (XATTR_ENTRY(XATTR_HDR(ptr) + 1))
#define XATTR_ROUND (3)
#define XATTR_ALIGN(size) (((size) + XATTR_ROUND) & ~XATTR_ROUND)
#define ENTRY_SIZE(entry) (XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) + \
(entry)->e_name_len + le16_to_cpu((entry)->e_value_size)))
#define XATTR_NEXT_ENTRY(entry) ((struct f2fs_xattr_entry *)((char *)(entry) +\
ENTRY_SIZE(entry)))
#define IS_XATTR_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
#define list_for_each_xattr(entry, addr) \
for (entry = XATTR_FIRST_ENTRY(addr);\
!IS_XATTR_LAST_ENTRY(entry);\
entry = XATTR_NEXT_ENTRY(entry))
#define VALID_XATTR_BLOCK_SIZE (PAGE_SIZE - sizeof(struct node_footer))
#define XATTR_PADDING_SIZE (sizeof(__u32))
#define MIN_OFFSET(i) XATTR_ALIGN(inline_xattr_size(i) + \
VALID_XATTR_BLOCK_SIZE)
#define MAX_VALUE_LEN(i) (MIN_OFFSET(i) - \
sizeof(struct f2fs_xattr_header) - \
sizeof(struct f2fs_xattr_entry))
#define MAX_INLINE_XATTR_SIZE \
(DEF_ADDRS_PER_INODE - \
F2FS_TOTAL_EXTRA_ATTR_SIZE / sizeof(__le32) - \
DEF_INLINE_RESERVED_SIZE - \
MIN_INLINE_DENTRY_SIZE / sizeof(__le32))
/*
* On-disk structure of f2fs_xattr
* We use inline xattrs space + 1 block for xattr.
*
* +--------------------+
* | f2fs_xattr_header |
* | |
* +--------------------+
* | f2fs_xattr_entry |
* | .e_name_index = 1 |
* | .e_name_len = 3 |
* | .e_value_size = 14 |
* | .e_name = "foo" |
* | "value_of_xattr" |<- value_offs = e_name + e_name_len
* +--------------------+
* | f2fs_xattr_entry |
* | .e_name_index = 4 |
* | .e_name = "bar" |
* +--------------------+
* | |
* | Free |
* | |
* +--------------------+<- MIN_OFFSET
* | node_footer |
* | (nid, ino, offset) |
* +--------------------+
*
**/
#ifdef CONFIG_F2FS_FS_XATTR
extern const struct xattr_handler f2fs_xattr_user_handler;
extern const struct xattr_handler f2fs_xattr_trusted_handler;
extern const struct xattr_handler f2fs_xattr_advise_handler;
extern const struct xattr_handler f2fs_xattr_security_handler;
extern const struct xattr_handler *f2fs_xattr_handlers[];
extern int f2fs_setxattr(struct inode *, int, const char *,
const void *, size_t, struct page *, int);
extern int f2fs_getxattr(struct inode *, int, const char *, void *,
size_t, struct page *);
extern ssize_t f2fs_listxattr(struct dentry *, char *, size_t);
#else
#define f2fs_xattr_handlers NULL
static inline int f2fs_setxattr(struct inode *inode, int index,
const char *name, const void *value, size_t size,
struct page *page, int flags)
{
return -EOPNOTSUPP;
}
static inline int f2fs_getxattr(struct inode *inode, int index,
const char *name, void *buffer,
size_t buffer_size, struct page *dpage)
{
return -EOPNOTSUPP;
}
static inline ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
size_t buffer_size)
{
return -EOPNOTSUPP;
}
#endif
#ifdef CONFIG_F2FS_FS_SECURITY
extern int f2fs_init_security(struct inode *, struct inode *,
const struct qstr *, struct page *);
#else
static inline int f2fs_init_security(struct inode *inode, struct inode *dir,
const struct qstr *qstr, struct page *ipage)
{
return 0;
}
#endif
#endif /* __F2FS_XATTR_H__ */