Re: [PATCH v2 03/14] fscrypt: adjust effective lblks based on extents

[Josef Bacik <josef@toxicpanda.com>]

On Sun, Jul 09, 2023 at 02:53:36PM -0400, Sweet Tea Dorminy wrote:
> If a filesystem uses extent-based encryption, then the offset within a
> file is not a constant which can be used for calculating an IV.
> For instance, the same extent could be blocks 0-8 in one file, and
> blocks 100-108 in another file. Instead, the block offset within the
> extent must be used instead.
> 
> Update all uses of logical block offset within the file to use logical
> block offset within the extent, if applicable.
> 
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> ---
>  fs/crypto/crypto.c       |  3 ++-
>  fs/crypto/inline_crypt.c | 24 +++++++++++++++++-------
>  2 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
> index 1b7e375b1c6b..d75f1b3f5795 100644
> --- a/fs/crypto/crypto.c
> +++ b/fs/crypto/crypto.c
> @@ -107,8 +107,9 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
>  	struct skcipher_request *req = NULL;
>  	DECLARE_CRYPTO_WAIT(wait);
>  	struct scatterlist dst, src;
> +	u64 ci_offset = 0;
>  	struct fscrypt_info *ci =
> -		fscrypt_get_lblk_info(inode, lblk_num, NULL, NULL);
> +		fscrypt_get_lblk_info(inode, lblk_num, &ci_offset, NULL);
>  	struct crypto_skcipher *tfm = ci->ci_enc_key->tfm;
>  	int res = 0;
>  
> diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
> index 885a2ec3d711..b3e7a5291d22 100644
> --- a/fs/crypto/inline_crypt.c
> +++ b/fs/crypto/inline_crypt.c
> @@ -267,12 +267,15 @@ void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
>  {
>  	const struct fscrypt_info *ci;
>  	u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
> +	u64 ci_offset = 0;
>  
>  	if (!fscrypt_inode_uses_inline_crypto(inode))
>  		return;
> -	ci = fscrypt_get_lblk_info(inode, first_lblk, NULL, NULL);
> +	ci = fscrypt_get_lblk_info(inode, first_lblk, &ci_offset, NULL);
> +	if (!ci)
> +		return;
>  
> -	fscrypt_generate_dun(ci, first_lblk, dun);
> +	fscrypt_generate_dun(ci, ci_offset, dun);
>  	bio_crypt_set_ctx(bio, ci->ci_enc_key->blk_key, dun, gfp_mask);
>  }
>  EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx);
> @@ -350,22 +353,23 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
>  	const struct bio_crypt_ctx *bc = bio->bi_crypt_context;
>  	u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
>  	struct fscrypt_info *ci;
> +	u64 ci_offset = 0;
>  
>  	if (!!bc != fscrypt_inode_uses_inline_crypto(inode))
>  		return false;
>  	if (!bc)
>  		return true;
>  
> -	ci = fscrypt_get_lblk_info(inode, next_lblk, NULL, NULL);
> +	ci = fscrypt_get_lblk_info(inode, next_lblk, &ci_offset, NULL);
>  	/*
>  	 * Comparing the key pointers is good enough, as all I/O for each key
>  	 * uses the same pointer.  I.e., there's currently no need to support
>  	 * merging requests where the keys are the same but the pointers differ.
>  	 */
> -	if (bc->bc_key != ci->ci_enc_key->blk_key)
> +	if (!ci || bc->bc_key != ci->ci_enc_key->blk_key)
>  		return false;
>  

This seems like an unrelated change, we weren't checking !ci before and the
behavior hasn't changed with the new code.  Thanks,

Josef