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SubjectRe: [PATCH crypto-next 07/23] block: cryptoloop: Remove VLA usage of skcipher
On Wed, 19 Sep 2018 at 04:11, Kees Cook <keescook@chromium.org> wrote:
>
> In the quest to remove all stack VLA usage from the kernel[1], this
> replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
> with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
> which uses a fixed stack size.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: linux-block@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/block/cryptoloop.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/block/cryptoloop.c b/drivers/block/cryptoloop.c
> index 7033a4beda66..254ee7d54e91 100644
> --- a/drivers/block/cryptoloop.c
> +++ b/drivers/block/cryptoloop.c
> @@ -45,7 +45,7 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
> char cms[LO_NAME_SIZE]; /* cipher-mode string */
> char *mode;
> char *cmsp = cms; /* c-m string pointer */
> - struct crypto_skcipher *tfm;
> + struct crypto_sync_skcipher *tfm;
>
> /* encryption breaks for non sector aligned offsets */
>
> @@ -80,13 +80,13 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
> *cmsp++ = ')';
> *cmsp = 0;
>
> - tfm = crypto_alloc_skcipher(cms, 0, CRYPTO_ALG_ASYNC);
> + tfm = crypto_alloc_sync_skcipher(cms, 0, 0);
> if (IS_ERR(tfm))
> return PTR_ERR(tfm);
>
> - err = crypto_skcipher_setkey(tfm, info->lo_encrypt_key,
> - info->lo_encrypt_key_size);
> -
> + err = crypto_sync_skcipher_setkey(tfm, info->lo_encrypt_key,
> + info->lo_encrypt_key_size);
> +
> if (err != 0)
> goto out_free_tfm;
>
> @@ -94,7 +94,7 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
> return 0;
>
> out_free_tfm:
> - crypto_free_skcipher(tfm);
> + crypto_free_sync_skcipher(tfm);
>
> out:
> return err;
> @@ -109,8 +109,8 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
> struct page *loop_page, unsigned loop_off,
> int size, sector_t IV)
> {
> - struct crypto_skcipher *tfm = lo->key_data;
> - SKCIPHER_REQUEST_ON_STACK(req, tfm);
> + struct crypto_sync_skcipher *tfm = lo->key_data;
> + SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
> struct scatterlist sg_out;
> struct scatterlist sg_in;
>
> @@ -119,7 +119,7 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
> unsigned in_offs, out_offs;
> int err;
>
> - skcipher_request_set_tfm(req, tfm);
> + skcipher_request_set_sync_tfm(req, tfm);
> skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
> NULL, NULL);
>

Does this work?

> @@ -175,9 +175,9 @@ cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
> static int
> cryptoloop_release(struct loop_device *lo)
> {
> - struct crypto_skcipher *tfm = lo->key_data;
> + struct crypto_sync_skcipher *tfm = lo->key_data;
> if (tfm != NULL) {
> - crypto_free_skcipher(tfm);
> + crypto_free_sync_skcipher(tfm);
> lo->key_data = NULL;
> return 0;
> }
> --
> 2.17.1
>

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