Re: [PATCH] crypto: powerpc - convert SPE AES algorithms to skcipher API

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On Mon, 14 Oct 2019 at 19:38, Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Mon, Oct 14, 2019 at 10:45:22AM +0200, Ard Biesheuvel wrote:
> > Hi Eric,
> >
> > On Sat, 12 Oct 2019 at 04:32, Eric Biggers <ebiggers@kernel.org> wrote:
> > >
> > > From: Eric Biggers <ebiggers@google.com>
> > >
> > > Convert the glue code for the PowerPC SPE implementations of AES-ECB,
> > > AES-CBC, AES-CTR, and AES-XTS from the deprecated "blkcipher" API to the
> > > "skcipher" API.
> > >
> > > Tested with:
> > >
> > >         export ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu-
> > >         make mpc85xx_defconfig
> > >         cat >> .config << EOF
> > >         # CONFIG_MODULES is not set
> > >         # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
> > >         CONFIG_DEBUG_KERNEL=y
> > >         CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y
> > >         CONFIG_CRYPTO_AES=y
> > >         CONFIG_CRYPTO_CBC=y
> > >         CONFIG_CRYPTO_CTR=y
> > >         CONFIG_CRYPTO_ECB=y
> > >         CONFIG_CRYPTO_XTS=y
> > >         CONFIG_CRYPTO_AES_PPC_SPE=y
> > >         EOF
> > >         make olddefconfig
> > >         make -j32
> > >         qemu-system-ppc -M mpc8544ds -cpu e500 -nographic \
> > >                 -kernel arch/powerpc/boot/zImage \
> > >                 -append cryptomgr.fuzz_iterations=1000
> > >
> > > Note that xts-ppc-spe still fails the comparison tests due to the lack
> > > of ciphertext stealing support.  This is not addressed by this patch.
> > >
> > > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > > ---
> > >  arch/powerpc/crypto/aes-spe-glue.c | 416 +++++++++++++----------------
> > >  crypto/Kconfig                     |   1 +
> > >  2 files changed, 186 insertions(+), 231 deletions(-)
> > >
> > > diff --git a/arch/powerpc/crypto/aes-spe-glue.c b/arch/powerpc/crypto/aes-spe-glue.c
> > > index 3a4ca7d32477..374e3e51e998 100644
> > > --- a/arch/powerpc/crypto/aes-spe-glue.c
> > > +++ b/arch/powerpc/crypto/aes-spe-glue.c
> > > @@ -17,6 +17,7 @@
> > >  #include <asm/byteorder.h>
> > >  #include <asm/switch_to.h>
> > >  #include <crypto/algapi.h>
> > > +#include <crypto/internal/skcipher.h>
> > >  #include <crypto/xts.h>
> > >
> > >  /*
> > > @@ -86,17 +87,13 @@ static void spe_end(void)
> > >         preempt_enable();
> > >  }
> > >
> > > -static int ppc_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
> > > -               unsigned int key_len)
> > > +static int expand_key(struct ppc_aes_ctx *ctx,
> > > +                     const u8 *in_key, unsigned int key_len)
> > >  {
> > > -       struct ppc_aes_ctx *ctx = crypto_tfm_ctx(tfm);
> > > -
> > >         if (key_len != AES_KEYSIZE_128 &&
> > >             key_len != AES_KEYSIZE_192 &&
> > > -           key_len != AES_KEYSIZE_256) {
> > > -               tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
> > > +           key_len != AES_KEYSIZE_256)
> > >                 return -EINVAL;
> > > -       }
> > >
> > >         switch (key_len) {
> > >         case AES_KEYSIZE_128:
> > > @@ -114,17 +111,40 @@ static int ppc_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
> > >         }
> > >
> > >         ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);
> > > +       return 0;
> > > +}
> > >
> > > +static int ppc_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
> > > +               unsigned int key_len)
> > > +{
> > > +       struct ppc_aes_ctx *ctx = crypto_tfm_ctx(tfm);
> > > +
> > > +       if (expand_key(ctx, in_key, key_len) != 0) {
> > > +               tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
> > > +               return -EINVAL;
> > > +       }
> > > +       return 0;
> > > +}
> > > +
> > > +static int ppc_aes_setkey_skcipher(struct crypto_skcipher *tfm,
> > > +                                  const u8 *in_key, unsigned int key_len)
> > > +{
> > > +       struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
> > > +
> > > +       if (expand_key(ctx, in_key, key_len) != 0) {
> > > +               crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
> > > +               return -EINVAL;
> > > +       }
> > >         return 0;
> > >  }
> > >
> > > -static int ppc_xts_setkey(struct crypto_tfm *tfm, const u8 *in_key,
> > > +static int ppc_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
> > >                    unsigned int key_len)
> > >  {
> > > -       struct ppc_xts_ctx *ctx = crypto_tfm_ctx(tfm);
> > > +       struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
> > >         int err;
> > >
> > > -       err = xts_check_key(tfm, in_key, key_len);
> > > +       err = xts_verify_key(tfm, in_key, key_len);
> > >         if (err)
> > >                 return err;
> > >
> > > @@ -133,7 +153,7 @@ static int ppc_xts_setkey(struct crypto_tfm *tfm, const u8 *in_key,
> > >         if (key_len != AES_KEYSIZE_128 &&
> > >             key_len != AES_KEYSIZE_192 &&
> > >             key_len != AES_KEYSIZE_256) {
> > > -               tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
> > > +               crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
> > >                 return -EINVAL;
> > >         }
> > >
> > > @@ -178,208 +198,154 @@ static void ppc_aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
> > >         spe_end();
> > >  }
> > >
> > > -static int ppc_ecb_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
> > > -                          struct scatterlist *src, unsigned int nbytes)
> > > +static int ppc_ecb_crypt(struct skcipher_request *req, bool enc)
> > >  {
> > > -       struct ppc_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
> > > -       struct blkcipher_walk walk;
> > > -       unsigned int ubytes;
> > > +       struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
> > > +       struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
> > > +       struct skcipher_walk walk;
> > > +       unsigned int nbytes;
> > >         int err;
> > >
> > > -       desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
> > > -       blkcipher_walk_init(&walk, dst, src, nbytes);
> > > -       err = blkcipher_walk_virt(desc, &walk);
> > > +       err = skcipher_walk_virt(&walk, req, false);
> > >
> >
> > Shouldn't atomic be set to 'true' here to retain the non-sleeping behavior?
>
> This was intentional since the non-sleeping behavior is unnecessary, as the call
> to skcipher_walk_done() is not within the spe_begin() / spe_end() section.
> I can split this into a separate patch if it would make it clearer, though.
>

No, I guess that is fine, but it deserves a mention in the commit log.