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Date:   Wed, 7 Sep 2022 19:02:01 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <chao@kernel.org>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Chao Yu <chao.yu@oppo.com>
Subject: Re: [PATCH v2] f2fs: fix to disallow getting inner inode via
 f2fs_iget()
Message-ID: <YxlNGeh6Sr4isEFf@google.com>
References: <20220830225358.300027-1-chao@kernel.org>
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On 08/31, Chao Yu wrote:
> From: Chao Yu <chao.yu@oppo.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?

> 
> Signed-off-by: Chao Yu <chao.yu@oppo.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