On Mon, Dec 09, 2019 at 12:39:18PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> As a sanity check, verify that the allocated crypto_skcipher actually
> has the ivsize that fscrypt is assuming it has. This will always be the
> case unless there's a bug. But if there ever is such a bug (e.g. like
> there was in earlier versions of the ESSIV conversion patch [1]) it's
> preferable for it to be immediately obvious, and not rely on the
> ciphertext verification tests failing due to uninitialized IV bytes.
>
> [1] https://lkml.kernel.org/linux-crypto/20190702215517.GA69157@xxxxxxxxx/
>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
> fs/crypto/keysetup.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index c9f4fe955971f..39fdea79e912f 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -91,6 +91,10 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
> pr_info("fscrypt: %s using implementation \"%s\"\n",
> mode->friendly_name, crypto_skcipher_driver_name(tfm));
> }
> + if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) {
> + err = -EINVAL;
> + goto err_free_tfm;
> + }
> crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
> err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);
> if (err)
> --
> 2.24.0.393.g34dc348eaf-goog
>
Applied to fscrypt.git#master for 5.6.
- Eric
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