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

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Message-ID: <0af788ed-8797-22a2-ae0c-433fdd6a2188@kernel.org>
Date:   Thu, 8 Sep 2022 10:11:41 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <chao.yu@...o.com>
Subject: Re: [PATCH v2] f2fs: fix to disallow getting inner inode via
 f2fs_iget()

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()?

Thanks,

> 
>>
>> Signed-off-by: Chao Yu <chao.yu@...o.com>
>> ---
>> v2:
>> - don't override errno from f2fs_check_nid_range()
>> - fix compile error
>>   fs/f2fs/compress.c |  2 +-
>>   fs/f2fs/f2fs.h     |  1 +
>>   fs/f2fs/inode.c    | 13 ++++++++++++-
>>   fs/f2fs/super.c    |  4 ++--
>>   4 files changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>> index 730256732a9e..c38b22bb6432 100644
>> --- a/fs/f2fs/compress.c
>> +++ b/fs/f2fs/compress.c
>> @@ -1947,7 +1947,7 @@ int f2fs_init_compress_inode(struct f2fs_sb_info *sbi)
>>   	if (!test_opt(sbi, COMPRESS_CACHE))
>>   		return 0;
>>   
>> -	inode = f2fs_iget(sbi->sb, F2FS_COMPRESS_INO(sbi));
>> +	inode = f2fs_iget_inner(sbi->sb, F2FS_COMPRESS_INO(sbi));
>>   	if (IS_ERR(inode))
>>   		return PTR_ERR(inode);
>>   	sbi->compress_inode = inode;
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 408d8034ed74..35f9e1a6a1bf 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -3467,6 +3467,7 @@ int f2fs_pin_file_control(struct inode *inode, bool inc);
>>   void f2fs_set_inode_flags(struct inode *inode);
>>   bool f2fs_inode_chksum_verify(struct f2fs_sb_info *sbi, struct page *page);
>>   void f2fs_inode_chksum_set(struct f2fs_sb_info *sbi, struct page *page);
>> +struct inode *f2fs_iget_inner(struct super_block *sb, unsigned long ino);
>>   struct inode *f2fs_iget(struct super_block *sb, unsigned long ino);
>>   struct inode *f2fs_iget_retry(struct super_block *sb, unsigned long ino);
>>   int f2fs_try_to_free_nats(struct f2fs_sb_info *sbi, int nr_shrink);
>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>> index 6d11c365d7b4..965f87c1dd63 100644
>> --- a/fs/f2fs/inode.c
>> +++ b/fs/f2fs/inode.c
>> @@ -480,7 +480,7 @@ static int do_read_inode(struct inode *inode)
>>   	return 0;
>>   }
>>   
>> -struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>> +struct inode *f2fs_iget_inner(struct super_block *sb, unsigned long ino)
>>   {
>>   	struct f2fs_sb_info *sbi = F2FS_SB(sb);
>>   	struct inode *inode;
>> @@ -568,6 +568,17 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>>   	return ERR_PTR(ret);
>>   }
>>   
>> +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);
>> +}
>> +
>>   struct inode *f2fs_iget_retry(struct super_block *sb, unsigned long ino)
>>   {
>>   	struct inode *inode;
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index b8e5fe244596..a5f5e7483791 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -4157,7 +4157,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>>   		goto free_xattr_cache;
>>   
>>   	/* get an inode for meta space */
>> -	sbi->meta_inode = f2fs_iget(sb, F2FS_META_INO(sbi));
>> +	sbi->meta_inode = f2fs_iget_inner(sb, F2FS_META_INO(sbi));
>>   	if (IS_ERR(sbi->meta_inode)) {
>>   		f2fs_err(sbi, "Failed to read F2FS meta data inode");
>>   		err = PTR_ERR(sbi->meta_inode);
>> @@ -4265,7 +4265,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>>   		goto free_nm;
>>   
>>   	/* get an inode for node space */
>> -	sbi->node_inode = f2fs_iget(sb, F2FS_NODE_INO(sbi));
>> +	sbi->node_inode = f2fs_iget_inner(sb, F2FS_NODE_INO(sbi));
>>   	if (IS_ERR(sbi->node_inode)) {
>>   		f2fs_err(sbi, "Failed to read node inode");
>>   		err = PTR_ERR(sbi->node_inode);
>> -- 
>> 2.25.1