Re: [PATCH] [PATCH] [crypto] LRW: use proper alignment.

[Stefan Hellermann <stefan@the2masters.de>]

Sebastian Siewior schrieb:
> The LRW blockmode uses a copy of the IV which is saved on the stack
> and may or may not be properly aligned. If it is not, it will break
> hardware cipher like the geode or padlock.
> This patch moves the copy of IV to the private structre which has the
> same aligment as the underlying cipher.
> Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>

Tested-by: Stefan Hellermann <stefan@the2masters.de>

> ---
>  crypto/lrw.c |   32 ++++++++++++++++++--------------
>  1 files changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/crypto/lrw.c b/crypto/lrw.c
> index 9d52e58..0c3ce3e 100644
> --- a/crypto/lrw.c
> +++ b/crypto/lrw.c
> @@ -27,7 +27,17 @@
>  #include <crypto/b128ops.h>
>  #include <crypto/gf128mul.h>
>  
> +struct sinfo {
> +	be128 t;
> +	struct crypto_tfm *tfm;
> +	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
> +};
> +
>  struct priv {
> +	/* s.t being the first member in this struct enforces proper alignment
> +	 * required by the underlying cipher without explicit knowing the it.
> +	 */
> +	struct sinfo s;
>  	struct crypto_cipher *child;
>  	/* optimizes multiplying a random (non incrementing, as at the
>  	 * start of a new sector) value with key2, we could also have
> @@ -83,12 +93,6 @@ static int setkey(struct crypto_tfm *parent, const u8 *key,
>  	return 0;
>  }
>  
> -struct sinfo {
> -	be128 t;
> -	struct crypto_tfm *tfm;
> -	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
> -};
> -
>  static inline void inc(be128 *iv)
>  {
>  	if (!(iv->b = cpu_to_be64(be64_to_cpu(iv->b) + 1)))
> @@ -128,14 +132,14 @@ static int crypt(struct blkcipher_desc *d,
>  	int err;
>  	unsigned int avail;
>  	const int bs = crypto_cipher_blocksize(ctx->child);
> -	struct sinfo s = {
> -		.tfm = crypto_cipher_tfm(ctx->child),
> -		.fn = fn
> -	};
> +	struct sinfo *s = &ctx->s;
>  	be128 *iv;
>  	u8 *wsrc;
>  	u8 *wdst;
>  
> +	s->tfm = crypto_cipher_tfm(ctx->child);
> +	s->fn = fn;
> +
>  	err = blkcipher_walk_virt(d, w);
>  	if (!(avail = w->nbytes))
>  		return err;
> @@ -145,10 +149,10 @@ static int crypt(struct blkcipher_desc *d,
>  
>  	/* calculate first value of T */
>  	iv = (be128 *)w->iv;
> -	s.t = *iv;
> +	s->t = *iv;
>  
>  	/* T <- I*Key2 */
> -	gf128mul_64k_bbe(&s.t, ctx->table);
> +	gf128mul_64k_bbe(&s->t, ctx->table);
>  
>  	goto first;
>  
> @@ -156,11 +160,11 @@ static int crypt(struct blkcipher_desc *d,
>  		do {
>  			/* T <- I*Key2, using the optimization
>  			 * discussed in the specification */
> -			be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
> +			be128_xor(&s->t, &s->t, &ctx->mulinc[get_index128(iv)]);
>  			inc(iv);
>  
>  first:
> -			lrw_round(&s, wdst, wsrc);
> +			lrw_round(s, wdst, wsrc);
>  
>  			wsrc += bs;
>  			wdst += bs;