[PATCH 08/21] crypto: x86/cast5 - drop CTR mode implementation

[Ard Biesheuvel <ardb@kernel.org>]

CAST5 in CTR mode is never used by the kernel directly, and is highly
unlikely to be relied upon by dm-crypt or algif_skcipher. So let's drop
the accelerated CTR mode implementation, and instead, rely on the CTR
template and the bare cipher.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/crypto/cast5_avx_glue.c | 103 --------------------
 crypto/Kconfig                   |   1 +
 2 files changed, 1 insertion(+), 103 deletions(-)

diff --git a/arch/x86/crypto/cast5_avx_glue.c b/arch/x86/crypto/cast5_avx_glue.c
index 384ccb00f9e1..e0d1c7903b29 100644
--- a/arch/x86/crypto/cast5_avx_glue.c
+++ b/arch/x86/crypto/cast5_avx_glue.c
@@ -23,8 +23,6 @@ asmlinkage void cast5_ecb_dec_16way(struct cast5_ctx *ctx, u8 *dst,
 				    const u8 *src);
 asmlinkage void cast5_cbc_dec_16way(struct cast5_ctx *ctx, u8 *dst,
 				    const u8 *src);
-asmlinkage void cast5_ctr_16way(struct cast5_ctx *ctx, u8 *dst, const u8 *src,
-				__be64 *iv);
 
 static int cast5_setkey_skcipher(struct crypto_skcipher *tfm, const u8 *key,
 				 unsigned int keylen)
@@ -214,92 +212,6 @@ static int cbc_decrypt(struct skcipher_request *req)
 	return err;
 }
 
-static void ctr_crypt_final(struct skcipher_walk *walk, struct cast5_ctx *ctx)
-{
-	u8 *ctrblk = walk->iv;
-	u8 keystream[CAST5_BLOCK_SIZE];
-	u8 *src = walk->src.virt.addr;
-	u8 *dst = walk->dst.virt.addr;
-	unsigned int nbytes = walk->nbytes;
-
-	__cast5_encrypt(ctx, keystream, ctrblk);
-	crypto_xor_cpy(dst, keystream, src, nbytes);
-
-	crypto_inc(ctrblk, CAST5_BLOCK_SIZE);
-}
-
-static unsigned int __ctr_crypt(struct skcipher_walk *walk,
-				struct cast5_ctx *ctx)
-{
-	const unsigned int bsize = CAST5_BLOCK_SIZE;
-	unsigned int nbytes = walk->nbytes;
-	u64 *src = (u64 *)walk->src.virt.addr;
-	u64 *dst = (u64 *)walk->dst.virt.addr;
-
-	/* Process multi-block batch */
-	if (nbytes >= bsize * CAST5_PARALLEL_BLOCKS) {
-		do {
-			cast5_ctr_16way(ctx, (u8 *)dst, (u8 *)src,
-					(__be64 *)walk->iv);
-
-			src += CAST5_PARALLEL_BLOCKS;
-			dst += CAST5_PARALLEL_BLOCKS;
-			nbytes -= bsize * CAST5_PARALLEL_BLOCKS;
-		} while (nbytes >= bsize * CAST5_PARALLEL_BLOCKS);
-
-		if (nbytes < bsize)
-			goto done;
-	}
-
-	/* Handle leftovers */
-	do {
-		u64 ctrblk;
-
-		if (dst != src)
-			*dst = *src;
-
-		ctrblk = *(u64 *)walk->iv;
-		be64_add_cpu((__be64 *)walk->iv, 1);
-
-		__cast5_encrypt(ctx, (u8 *)&ctrblk, (u8 *)&ctrblk);
-		*dst ^= ctrblk;
-
-		src += 1;
-		dst += 1;
-		nbytes -= bsize;
-	} while (nbytes >= bsize);
-
-done:
-	return nbytes;
-}
-
-static int ctr_crypt(struct skcipher_request *req)
-{
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	struct cast5_ctx *ctx = crypto_skcipher_ctx(tfm);
-	bool fpu_enabled = false;
-	struct skcipher_walk walk;
-	unsigned int nbytes;
-	int err;
-
-	err = skcipher_walk_virt(&walk, req, false);
-
-	while ((nbytes = walk.nbytes) >= CAST5_BLOCK_SIZE) {
-		fpu_enabled = cast5_fpu_begin(fpu_enabled, &walk, nbytes);
-		nbytes = __ctr_crypt(&walk, ctx);
-		err = skcipher_walk_done(&walk, nbytes);
-	}
-
-	cast5_fpu_end(fpu_enabled);
-
-	if (walk.nbytes) {
-		ctr_crypt_final(&walk, ctx);
-		err = skcipher_walk_done(&walk, 0);
-	}
-
-	return err;
-}
-
 static struct skcipher_alg cast5_algs[] = {
 	{
 		.base.cra_name		= "__ecb(cast5)",
@@ -328,21 +240,6 @@ static struct skcipher_alg cast5_algs[] = {
 		.setkey			= cast5_setkey_skcipher,
 		.encrypt		= cbc_encrypt,
 		.decrypt		= cbc_decrypt,
-	}, {
-		.base.cra_name		= "__ctr(cast5)",
-		.base.cra_driver_name	= "__ctr-cast5-avx",
-		.base.cra_priority	= 200,
-		.base.cra_flags		= CRYPTO_ALG_INTERNAL,
-		.base.cra_blocksize	= 1,
-		.base.cra_ctxsize	= sizeof(struct cast5_ctx),
-		.base.cra_module	= THIS_MODULE,
-		.min_keysize		= CAST5_MIN_KEY_SIZE,
-		.max_keysize		= CAST5_MAX_KEY_SIZE,
-		.ivsize			= CAST5_BLOCK_SIZE,
-		.chunksize		= CAST5_BLOCK_SIZE,
-		.setkey			= cast5_setkey_skcipher,
-		.encrypt		= ctr_crypt,
-		.decrypt		= ctr_crypt,
 	}
 };
 
diff --git a/crypto/Kconfig b/crypto/Kconfig
index dd48c3bab3f5..fed73fff5a65 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1372,6 +1372,7 @@ config CRYPTO_CAST5_AVX_X86_64
 	select CRYPTO_CAST5
 	select CRYPTO_CAST_COMMON
 	select CRYPTO_SIMD
+	imply CRYPTO_CTR
 	help
 	  The CAST5 encryption algorithm (synonymous with CAST-128) is
 	  described in RFC2144.
-- 
2.17.1