crypto: x86/cast6 - drop CTR mode implementation

CAST6 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.

Acked-by: Eric Biggers <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

arch/x86/crypto/cast6-avx-x86_64-asm_64.S

@@ -410,31 +410,3 @@ SYM_FUNC_START(cast6_cbc_dec_8way)
 	FRAME_END
 	ret;
 SYM_FUNC_END(cast6_cbc_dec_8way)
-
-SYM_FUNC_START(cast6_ctr_8way)
-	/* input:
-	 *	%rdi: ctx, CTX
-	 *	%rsi: dst
-	 *	%rdx: src
-	 *	%rcx: iv (little endian, 128bit)
-	 */
-	FRAME_BEGIN
-	pushq %r12;
-	pushq %r15
-
-	movq %rdi, CTX;
-	movq %rsi, %r11;
-	movq %rdx, %r12;
-
-	load_ctr_8way(%rcx, .Lbswap128_mask, RA1, RB1, RC1, RD1, RA2, RB2, RC2,
-		      RD2, RX, RKR, RKM);
-
-	call __cast6_enc_blk8;
-
-	store_ctr_8way(%r12, %r11, RA1, RB1, RC1, RD1, RA2, RB2, RC2, RD2);
-
-	popq %r15;
-	popq %r12;
-	FRAME_END
-	ret;
-SYM_FUNC_END(cast6_ctr_8way)

arch/x86/crypto/cast6_avx_glue.c

@@ -23,28 +23,13 @@ asmlinkage void cast6_ecb_enc_8way(const void *ctx, u8 *dst, const u8 *src);
 asmlinkage void cast6_ecb_dec_8way(const void *ctx, u8 *dst, const u8 *src);
 
 asmlinkage void cast6_cbc_dec_8way(const void *ctx, u8 *dst, const u8 *src);
-asmlinkage void cast6_ctr_8way(const void *ctx, u8 *dst, const u8 *src,
-			       le128 *iv);
 
 static int cast6_setkey_skcipher(struct crypto_skcipher *tfm,
 				 const u8 *key, unsigned int keylen)
 {
 	return cast6_setkey(&tfm->base, key, keylen);
 }
 
-static void cast6_crypt_ctr(const void *ctx, u8 *d, const u8 *s, le128 *iv)
-{
-	be128 ctrblk;
-	u128 *dst = (u128 *)d;
-	const u128 *src = (const u128 *)s;
-
-	le128_to_be128(&ctrblk, iv);
-	le128_inc(iv);
-
-	__cast6_encrypt(ctx, (u8 *)&ctrblk, (u8 *)&ctrblk);
-	u128_xor(dst, src, (u128 *)&ctrblk);
-}
-
 static const struct common_glue_ctx cast6_enc = {
 	.num_funcs = 2,
 	.fpu_blocks_limit = CAST6_PARALLEL_BLOCKS,
@@ -58,19 +43,6 @@ static const struct common_glue_ctx cast6_enc = {
 	} }
 };
 
-static const struct common_glue_ctx cast6_ctr = {
-	.num_funcs = 2,
-	.fpu_blocks_limit = CAST6_PARALLEL_BLOCKS,
-
-	.funcs = { {
-		.num_blocks = CAST6_PARALLEL_BLOCKS,
-		.fn_u = { .ctr = cast6_ctr_8way }
-	}, {
-		.num_blocks = 1,
-		.fn_u = { .ctr = cast6_crypt_ctr }
-	} }
-};
-
 static const struct common_glue_ctx cast6_dec = {
 	.num_funcs = 2,
 	.fpu_blocks_limit = CAST6_PARALLEL_BLOCKS,
@@ -117,11 +89,6 @@ static int cbc_decrypt(struct skcipher_request *req)
 	return glue_cbc_decrypt_req_128bit(&cast6_dec_cbc, req);
 }
 
-static int ctr_crypt(struct skcipher_request *req)
-{
-	return glue_ctr_req_128bit(&cast6_ctr, req);
-}
-
 static struct skcipher_alg cast6_algs[] = {
 	{
 		.base.cra_name		= "__ecb(cast6)",
@@ -150,21 +117,6 @@ static struct skcipher_alg cast6_algs[] = {
 		.setkey			= cast6_setkey_skcipher,
 		.encrypt		= cbc_encrypt,
 		.decrypt		= cbc_decrypt,
-	}, {
-		.base.cra_name		= "__ctr(cast6)",
-		.base.cra_driver_name	= "__ctr-cast6-avx",
-		.base.cra_priority	= 200,
-		.base.cra_flags		= CRYPTO_ALG_INTERNAL,
-		.base.cra_blocksize	= 1,
-		.base.cra_ctxsize	= sizeof(struct cast6_ctx),
-		.base.cra_module	= THIS_MODULE,
-		.min_keysize		= CAST6_MIN_KEY_SIZE,
-		.max_keysize		= CAST6_MAX_KEY_SIZE,
-		.ivsize			= CAST6_BLOCK_SIZE,
-		.chunksize		= CAST6_BLOCK_SIZE,
-		.setkey			= cast6_setkey_skcipher,
-		.encrypt		= ctr_crypt,
-		.decrypt		= ctr_crypt,
 	},
 };
 

crypto/Kconfig

@@ -1397,6 +1397,7 @@ config CRYPTO_CAST6_AVX_X86_64
 	select CRYPTO_GLUE_HELPER_X86
 	select CRYPTO_SIMD
 	imply CRYPTO_XTS
+	imply CRYPTO_CTR
 	help
 	  The CAST6 encryption algorithm (synonymous with CAST-256) is
 	  described in RFC2612.