linux-kernel - Re: [PATCH v2] f2fs: fix to disallow getting inner inode via f2fs

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Message-ID: <4efaecb4-7179-ae6c-05b6-49a168b3c8bd@kernel.org>
Date:   Tue, 13 Sep 2022 14:44:24 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] f2fs: fix to disallow getting inner inode via
 f2fs_iget()

On 2022/9/13 13:54, Jaegeuk Kim wrote:
> On 09/13, Chao Yu wrote:
>> On 2022/9/12 23:39, Jaegeuk Kim wrote:
>>> On 09/08, Chao Yu wrote:
>>>> On 2022/9/8 10:19, Jaegeuk Kim wrote:
>>>>> On 09/08, Chao Yu wrote:
>>>>>> On 2022/9/8 10:02, Jaegeuk Kim wrote:
>>>>>>> On 08/31, Chao Yu wrote:
>>>>>>>> From: Chao Yu <chao.yu@...o.com>
>>>>>>>>
>>>>>>>> Introduce f2fs_iget_inner() for f2fs_fill_super() to get inner inode:
>>>>>>>> meta inode, node inode or compressed inode, and add f2fs_check_nid_range()
>>>>>>>> in f2fs_iget() to avoid getting inner inode from external interfaces.
>>>>>>>
>>>>>>> So, we don't want to check the range of inner inode numbers? What'd be the
>>>>>>> way to check it's okay?
>>>>>>
>>>>>> For node_ino, meta_ino, root_ino, we have checked them in sanity_check_raw_super()
>>>>>> as below:
>>>>>>
>>>>>> 	/* check reserved ino info */
>>>>>> 	if (le32_to_cpu(raw_super->node_ino) != 1 ||
>>>>>> 		le32_to_cpu(raw_super->meta_ino) != 2 ||
>>>>>> 		le32_to_cpu(raw_super->root_ino) != 3) {
>>>>>> 		f2fs_info(sbi, "Invalid Fs Meta Ino: node(%u) meta(%u) root(%u)",
>>>>>> 			  le32_to_cpu(raw_super->node_ino),
>>>>>> 			  le32_to_cpu(raw_super->meta_ino),
>>>>>> 			  le32_to_cpu(raw_super->root_ino));
>>>>>> 		return -EFSCORRUPTED;
>>>>>> 	}
>>>>>>
>>>>>> compressed_ino should always be NM_I(sbi)->max_nid, it can be checked in
>>>>>> f2fs_init_compress_inode()?
>>>>>
>>>>> Hmm, I'm not sure whether we really need this patch, since it'd look better
>>>>> to handle all the iget with single f2fs_iget?
>>>>
>>>> Well, the main concern is previously f2fs_iget() won't check validation for inner
>>>> inode due to it will skip do_read_inode() - f2fs_check_nid_range(), so that in a
>>>> fuzzed image, caller may pass inner ino into f2fs_iget(), result in incorrect use
>>>> of inner inode. So I add f2fs_check_nid_range() in prior to f2fs_iget_inner() in
>>>> f2fs_iget() as below to detect and avoid this case.
>>>
>>> FWIW, sanity_check_raw_super() checked the inode numbers.
>>
>> However, previously, f2fs_iget() will return inner inode to caller directly, if caller
>> passes meta_ino, node_ino or compress_ino to f2fs_iget()?
> 
> Do you want to do sanity check on corrupted dentry? If so, how about checking

Yes, including:

- corrupted ino in dentry
- corrupted ino of orphan inode

As I replied in this thread:

https://lore.kernel.org/lkml/b1c74dc1-8d01-9041-9469-036273c5618d@kernel.org/

> it in f2fs_iget instead?
> 
> 	if (is_meta_ino(ino)) {
> 		if (!(inode->i_state & I_NEW)
> 			return -EFSCORRUPTED;
> 		goto make_now;
> 	}

Fine to me, let me revise in v3.

Thanks,

> 
>>
>> Thanks,
>>
>>>
>>>>
>>>>>>>> +struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>>>>>>>> +{
>>>>>>>> +	int ret;
>>>>>>>> +
>>>>>>>> +	ret = f2fs_check_nid_range(F2FS_SB(sb), ino);
>>>>>>>> +	if (ret)
>>>>>>>> +		return ERR_PTR(ret);
>>>>>>>> +
>>>>>>>> +	return f2fs_iget_inner(sb, ino);