crypto: vmx - ghash: do nosimd fallback manually
authorDaniel Axtens <dja@axtens.net>
Thu, 16 May 2019 15:40:02 +0000 (01:40 +1000)
committerHerbert Xu <herbert@gondor.apana.org.au>
Fri, 17 May 2019 05:36:54 +0000 (13:36 +0800)
VMX ghash was using a fallback that did not support interleaving simd
and nosimd operations, leading to failures in the extended test suite.

If I understood correctly, Eric's suggestion was to use the same
data format that the generic code uses, allowing us to call into it
with the same contexts. I wasn't able to get that to work - I think
there's a very different key structure and data layout being used.

So instead steal the arm64 approach and perform the fallback
operations directly if required.

Fixes: cc333cd68dfa ("crypto: vmx - Adding GHASH routines for VMX module")
Cc: stable@vger.kernel.org # v4.1+
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
drivers/crypto/vmx/ghash.c

index b5a6883..14807ac 100644 (file)
@@ -1,22 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
 /**
  * GHASH routines supporting VMX instructions on the Power 8
  *
- * Copyright (C) 2015 International Business Machines Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 only.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * Copyright (C) 2015, 2019 International Business Machines Inc.
  *
  * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
+ *
+ * Extended by Daniel Axtens <dja@axtens.net> to replace the fallback
+ * mechanism. The new approach is based on arm64 code, which is:
+ *   Copyright (C) 2014 - 2018 Linaro Ltd. <ard.biesheuvel@linaro.org>
  */
 
 #include <linux/types.h>
@@ -38,70 +30,25 @@ void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],
                  const u8 *in, size_t len);
 
 struct p8_ghash_ctx {
+       /* key used by vector asm */
        u128 htable[16];
-       struct crypto_shash *fallback;
+       /* key used by software fallback */
+       be128 key;
 };
 
 struct p8_ghash_desc_ctx {
        u64 shash[2];
        u8 buffer[GHASH_DIGEST_SIZE];
        int bytes;
-       struct shash_desc fallback_desc;
 };
 
-static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
-{
-       const char *alg = "ghash-generic";
-       struct crypto_shash *fallback;
-       struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
-       struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
-
-       fallback = crypto_alloc_shash(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
-       if (IS_ERR(fallback)) {
-               printk(KERN_ERR
-                      "Failed to allocate transformation for '%s': %ld\n",
-                      alg, PTR_ERR(fallback));
-               return PTR_ERR(fallback);
-       }
-
-       crypto_shash_set_flags(fallback,
-                              crypto_shash_get_flags((struct crypto_shash
-                                                      *) tfm));
-
-       /* Check if the descsize defined in the algorithm is still enough. */
-       if (shash_tfm->descsize < sizeof(struct p8_ghash_desc_ctx)
-           + crypto_shash_descsize(fallback)) {
-               printk(KERN_ERR
-                      "Desc size of the fallback implementation (%s) does not match the expected value: %lu vs %u\n",
-                      alg,
-                      shash_tfm->descsize - sizeof(struct p8_ghash_desc_ctx),
-                      crypto_shash_descsize(fallback));
-               return -EINVAL;
-       }
-       ctx->fallback = fallback;
-
-       return 0;
-}
-
-static void p8_ghash_exit_tfm(struct crypto_tfm *tfm)
-{
-       struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
-
-       if (ctx->fallback) {
-               crypto_free_shash(ctx->fallback);
-               ctx->fallback = NULL;
-       }
-}
-
 static int p8_ghash_init(struct shash_desc *desc)
 {
-       struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
        struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
        dctx->bytes = 0;
        memset(dctx->shash, 0, GHASH_DIGEST_SIZE);
-       dctx->fallback_desc.tfm = ctx->fallback;
-       return crypto_shash_init(&dctx->fallback_desc);
+       return 0;
 }
 
 static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
@@ -119,7 +66,51 @@ static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
        disable_kernel_vsx();
        pagefault_enable();
        preempt_enable();
-       return crypto_shash_setkey(ctx->fallback, key, keylen);
+
+       memcpy(&ctx->key, key, GHASH_BLOCK_SIZE);
+
+       return 0;
+}
+
+static inline void __ghash_block(struct p8_ghash_ctx *ctx,
+                                struct p8_ghash_desc_ctx *dctx)
+{
+       if (crypto_simd_usable()) {
+               preempt_disable();
+               pagefault_disable();
+               enable_kernel_vsx();
+               gcm_ghash_p8(dctx->shash, ctx->htable,
+                               dctx->buffer, GHASH_DIGEST_SIZE);
+               disable_kernel_vsx();
+               pagefault_enable();
+               preempt_enable();
+       } else {
+               crypto_xor((u8 *)dctx->shash, dctx->buffer, GHASH_BLOCK_SIZE);
+               gf128mul_lle((be128 *)dctx->shash, &ctx->key);
+       }
+}
+
+static inline void __ghash_blocks(struct p8_ghash_ctx *ctx,
+                                 struct p8_ghash_desc_ctx *dctx,
+                                 const u8 *src, unsigned int srclen)
+{
+       if (crypto_simd_usable()) {
+               preempt_disable();
+               pagefault_disable();
+               enable_kernel_vsx();
+               gcm_ghash_p8(dctx->shash, ctx->htable,
+                               src, srclen);
+               disable_kernel_vsx();
+               pagefault_enable();
+               preempt_enable();
+       } else {
+               while (srclen >= GHASH_BLOCK_SIZE) {
+                       crypto_xor((u8 *)dctx->shash, src, GHASH_BLOCK_SIZE);
+                       gf128mul_lle((be128 *)dctx->shash, &ctx->key);
+                       srclen -= GHASH_BLOCK_SIZE;
+                       src += GHASH_BLOCK_SIZE;
+               }
+       }
 }
 
 static int p8_ghash_update(struct shash_desc *desc,
@@ -129,49 +120,33 @@ static int p8_ghash_update(struct shash_desc *desc,
        struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
        struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
-       if (!crypto_simd_usable()) {
-               return crypto_shash_update(&dctx->fallback_desc, src,
-                                          srclen);
-       } else {
-               if (dctx->bytes) {
-                       if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
-                               memcpy(dctx->buffer + dctx->bytes, src,
-                                      srclen);
-                               dctx->bytes += srclen;
-                               return 0;
-                       }
+       if (dctx->bytes) {
+               if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
                        memcpy(dctx->buffer + dctx->bytes, src,
-                              GHASH_DIGEST_SIZE - dctx->bytes);
-                       preempt_disable();
-                       pagefault_disable();
-                       enable_kernel_vsx();
-                       gcm_ghash_p8(dctx->shash, ctx->htable,
-                                    dctx->buffer, GHASH_DIGEST_SIZE);
-                       disable_kernel_vsx();
-                       pagefault_enable();
-                       preempt_enable();
-                       src += GHASH_DIGEST_SIZE - dctx->bytes;
-                       srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
-                       dctx->bytes = 0;
-               }
-               len = srclen & ~(GHASH_DIGEST_SIZE - 1);
-               if (len) {
-                       preempt_disable();
-                       pagefault_disable();
-                       enable_kernel_vsx();
-                       gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
-                       disable_kernel_vsx();
-                       pagefault_enable();
-                       preempt_enable();
-                       src += len;
-                       srclen -= len;
-               }
-               if (srclen) {
-                       memcpy(dctx->buffer, src, srclen);
-                       dctx->bytes = srclen;
+                               srclen);
+                       dctx->bytes += srclen;
+                       return 0;
                }
-               return 0;
+               memcpy(dctx->buffer + dctx->bytes, src,
+                       GHASH_DIGEST_SIZE - dctx->bytes);
+
+               __ghash_block(ctx, dctx);
+
+               src += GHASH_DIGEST_SIZE - dctx->bytes;
+               srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
+               dctx->bytes = 0;
+       }
+       len = srclen & ~(GHASH_DIGEST_SIZE - 1);
+       if (len) {
+               __ghash_blocks(ctx, dctx, src, len);
+               src += len;
+               srclen -= len;
        }
+       if (srclen) {
+               memcpy(dctx->buffer, src, srclen);
+               dctx->bytes = srclen;
+       }
+       return 0;
 }
 
 static int p8_ghash_final(struct shash_desc *desc, u8 *out)
@@ -180,25 +155,14 @@ static int p8_ghash_final(struct shash_desc *desc, u8 *out)
        struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
        struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
 
-       if (!crypto_simd_usable()) {
-               return crypto_shash_final(&dctx->fallback_desc, out);
-       } else {
-               if (dctx->bytes) {
-                       for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
-                               dctx->buffer[i] = 0;
-                       preempt_disable();
-                       pagefault_disable();
-                       enable_kernel_vsx();
-                       gcm_ghash_p8(dctx->shash, ctx->htable,
-                                    dctx->buffer, GHASH_DIGEST_SIZE);
-                       disable_kernel_vsx();
-                       pagefault_enable();
-                       preempt_enable();
-                       dctx->bytes = 0;
-               }
-               memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
-               return 0;
+       if (dctx->bytes) {
+               for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
+                       dctx->buffer[i] = 0;
+               __ghash_block(ctx, dctx);
+               dctx->bytes = 0;
        }
+       memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
+       return 0;
 }
 
 struct shash_alg p8_ghash_alg = {
@@ -213,11 +177,8 @@ struct shash_alg p8_ghash_alg = {
                 .cra_name = "ghash",
                 .cra_driver_name = "p8_ghash",
                 .cra_priority = 1000,
-                .cra_flags = CRYPTO_ALG_NEED_FALLBACK,
                 .cra_blocksize = GHASH_BLOCK_SIZE,
                 .cra_ctxsize = sizeof(struct p8_ghash_ctx),
                 .cra_module = THIS_MODULE,
-                .cra_init = p8_ghash_init_tfm,
-                .cra_exit = p8_ghash_exit_tfm,
        },
 };