linux-ext4 - Re: [PATCH] fscrypt: fix inline encryption not used on new files

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Date:   Thu, 12 Nov 2020 12:29:16 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     linux-fscrypt@...r.kernel.org
Cc:     linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        Satya Tangirala <satyat@...gle.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>
Subject: Re: [PATCH] fscrypt: fix inline encryption not used on new files

On Tue, Nov 10, 2020 at 05:52:24PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> The new helper function fscrypt_prepare_new_inode() runs before
> S_ENCRYPTED has been set on the new inode.  This accidentally made
> fscrypt_select_encryption_impl() never enable inline encryption on newly
> created files, due to its use of fscrypt_needs_contents_encryption()
> which only returns true when S_ENCRYPTED is set.
> 
> Fix this by using S_ISREG() directly instead of
> fscrypt_needs_contents_encryption(), analogous to what
> select_encryption_mode() does.
> 
> I didn't notice this earlier because by design, the user-visible
> behavior is the same (other than performance, potentially) regardless of
> whether inline encryption is used or not.
> 
> Fixes: a992b20cd4ee ("fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()")
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
>  fs/crypto/inline_crypt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
> index 89bffa82ed74a..c57bebfa48fea 100644
> --- a/fs/crypto/inline_crypt.c
> +++ b/fs/crypto/inline_crypt.c
> @@ -74,7 +74,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
>  	int i;
>  
>  	/* The file must need contents encryption, not filenames encryption */
> -	if (!fscrypt_needs_contents_encryption(inode))
> +	if (!S_ISREG(inode->i_mode))
>  		return 0;
>  
>  	/* The crypto mode must have a blk-crypto counterpart */
> 
> base-commit: 92cfcd030e4b1de11a6b1edb0840e55c26332d31

Applied to fscrypt.git#for-stable for 5.10.

- Eric