crypto: chacha20 - convert generic and x86 versions to skcipher

This converts the ChaCha20 code from a blkcipher to a skcipher, which
is now the preferred way to implement symmetric block and stream ciphers.

This ports the generic and x86 versions at the same time because the
latter reuses routines of the former.

Note that the skcipher_walk() API guarantees that all presented blocks
except the final one are a multiple of the chunk size, so we can simplify
the encrypt() routine somewhat.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/chacha20_glue.c

@@ -11,7 +11,7 @@
 
 #include <crypto/algapi.h>
 #include <crypto/chacha20.h>
-#include <linux/crypto.h>
+#include <crypto/internal/skcipher.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <asm/fpu/api.h>
@@ -63,36 +63,34 @@ static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
 	}
 }
 
-static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
-			 struct scatterlist *src, unsigned int nbytes)
+static int chacha20_simd(struct skcipher_request *req)
 {
-	u32 *state, state_buf[16 + (CHACHA20_STATE_ALIGN / sizeof(u32)) - 1];
-	struct blkcipher_walk walk;
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
+	u32 state[16] __aligned(CHACHA20_STATE_ALIGN);
+	struct skcipher_walk walk;
 	int err;
 
-	if (nbytes <= CHACHA20_BLOCK_SIZE || !may_use_simd())
-		return crypto_chacha20_crypt(desc, dst, src, nbytes);
+	if (req->cryptlen <= CHACHA20_BLOCK_SIZE || !may_use_simd())
+		return crypto_chacha20_crypt(req);
 
-	state = (u32 *)roundup((uintptr_t)state_buf, CHACHA20_STATE_ALIGN);
+	err = skcipher_walk_virt(&walk, req, true);
 
-	blkcipher_walk_init(&walk, dst, src, nbytes);
-	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
-
-	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
+	crypto_chacha20_init(state, ctx, walk.iv);
 
 	kernel_fpu_begin();
 
 	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
 		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
 				rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
-		err = blkcipher_walk_done(desc, &walk,
-					  walk.nbytes % CHACHA20_BLOCK_SIZE);
+		err = skcipher_walk_done(&walk,
+					 walk.nbytes % CHACHA20_BLOCK_SIZE);
 	}
 
 	if (walk.nbytes) {
 		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
 				walk.nbytes);
-		err = blkcipher_walk_done(desc, &walk, 0);
+		err = skcipher_walk_done(&walk, 0);
 	}
 
 	kernel_fpu_end();
@@ -100,27 +98,22 @@ static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
 	return err;
 }
 
-static struct crypto_alg alg = {
-	.cra_name		= "chacha20",
-	.cra_driver_name	= "chacha20-simd",
-	.cra_priority		= 300,
-	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
-	.cra_blocksize		= 1,
-	.cra_type		= &crypto_blkcipher_type,
-	.cra_ctxsize		= sizeof(struct chacha20_ctx),
-	.cra_alignmask		= sizeof(u32) - 1,
-	.cra_module		= THIS_MODULE,
-	.cra_u			= {
-		.blkcipher = {
-			.min_keysize	= CHACHA20_KEY_SIZE,
-			.max_keysize	= CHACHA20_KEY_SIZE,
-			.ivsize		= CHACHA20_IV_SIZE,
-			.geniv		= "seqiv",
-			.setkey		= crypto_chacha20_setkey,
-			.encrypt	= chacha20_simd,
-			.decrypt	= chacha20_simd,
-		},
-	},
+static struct skcipher_alg alg = {
+	.base.cra_name		= "chacha20",
+	.base.cra_driver_name	= "chacha20-simd",
+	.base.cra_priority	= 300,
+	.base.cra_blocksize	= 1,
+	.base.cra_ctxsize	= sizeof(struct chacha20_ctx),
+	.base.cra_alignmask	= sizeof(u32) - 1,
+	.base.cra_module	= THIS_MODULE,
+
+	.min_keysize		= CHACHA20_KEY_SIZE,
+	.max_keysize		= CHACHA20_KEY_SIZE,
+	.ivsize			= CHACHA20_IV_SIZE,
+	.chunksize		= CHACHA20_BLOCK_SIZE,
+	.setkey			= crypto_chacha20_setkey,
+	.encrypt		= chacha20_simd,
+	.decrypt		= chacha20_simd,
 };
 
 static int __init chacha20_simd_mod_init(void)
@@ -133,12 +126,12 @@ static int __init chacha20_simd_mod_init(void)
 			    boot_cpu_has(X86_FEATURE_AVX2) &&
 			    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
 #endif
-	return crypto_register_alg(&alg);
+	return crypto_register_skcipher(&alg);
 }
 
 static void __exit chacha20_simd_mod_fini(void)
 {
-	crypto_unregister_alg(&alg);
+	crypto_unregister_skcipher(&alg);
 }
 
 module_init(chacha20_simd_mod_init);

crypto/chacha20_generic.c

@@ -10,10 +10,9 @@
  */
 
 #include <crypto/algapi.h>
-#include <linux/crypto.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
 #include <crypto/chacha20.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/module.h>
 
 static inline u32 le32_to_cpuvp(const void *p)
 {
@@ -63,10 +62,10 @@ void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_init);
 
-int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
+int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
 			   unsigned int keysize)
 {
-	struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
 	int i;
 
 	if (keysize != CHACHA20_KEY_SIZE)
@@ -79,66 +78,54 @@ int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
 
-int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
-			  struct scatterlist *src, unsigned int nbytes)
+int crypto_chacha20_crypt(struct skcipher_request *req)
 {
-	struct blkcipher_walk walk;
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct skcipher_walk walk;
 	u32 state[16];
 	int err;
 
-	blkcipher_walk_init(&walk, dst, src, nbytes);
-	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
-
-	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
+	err = skcipher_walk_virt(&walk, req, true);
 
-	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
-		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
-				 rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
-		err = blkcipher_walk_done(desc, &walk,
-					  walk.nbytes % CHACHA20_BLOCK_SIZE);
-	}
+	crypto_chacha20_init(state, ctx, walk.iv);
 
-	if (walk.nbytes) {
+	while (walk.nbytes > 0) {
 		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
 				 walk.nbytes);
-		err = blkcipher_walk_done(desc, &walk, 0);
+		err = skcipher_walk_done(&walk, 0);
 	}
 
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
 
-static struct crypto_alg alg = {
-	.cra_name		= "chacha20",
-	.cra_driver_name	= "chacha20-generic",
-	.cra_priority		= 100,
-	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
-	.cra_blocksize		= 1,
-	.cra_type		= &crypto_blkcipher_type,
-	.cra_ctxsize		= sizeof(struct chacha20_ctx),
-	.cra_alignmask		= sizeof(u32) - 1,
-	.cra_module		= THIS_MODULE,
-	.cra_u			= {
-		.blkcipher = {
-			.min_keysize	= CHACHA20_KEY_SIZE,
-			.max_keysize	= CHACHA20_KEY_SIZE,
-			.ivsize		= CHACHA20_IV_SIZE,
-			.geniv		= "seqiv",
-			.setkey		= crypto_chacha20_setkey,
-			.encrypt	= crypto_chacha20_crypt,
-			.decrypt	= crypto_chacha20_crypt,
-		},
-	},
+static struct skcipher_alg alg = {
+	.base.cra_name		= "chacha20",
+	.base.cra_driver_name	= "chacha20-generic",
+	.base.cra_priority	= 100,
+	.base.cra_blocksize	= 1,
+	.base.cra_ctxsize	= sizeof(struct chacha20_ctx),
+	.base.cra_alignmask	= sizeof(u32) - 1,
+	.base.cra_module	= THIS_MODULE,
+
+	.min_keysize		= CHACHA20_KEY_SIZE,
+	.max_keysize		= CHACHA20_KEY_SIZE,
+	.ivsize			= CHACHA20_IV_SIZE,
+	.chunksize		= CHACHA20_BLOCK_SIZE,
+	.setkey			= crypto_chacha20_setkey,
+	.encrypt		= crypto_chacha20_crypt,
+	.decrypt		= crypto_chacha20_crypt,
 };
 
 static int __init chacha20_generic_mod_init(void)
 {
-	return crypto_register_alg(&alg);
+	return crypto_register_skcipher(&alg);
 }
 
 static void __exit chacha20_generic_mod_fini(void)
 {
-	crypto_unregister_alg(&alg);
+	crypto_unregister_skcipher(&alg);
 }
 
 module_init(chacha20_generic_mod_init);

include/crypto/chacha20.h

@@ -5,6 +5,7 @@
 #ifndef _CRYPTO_CHACHA20_H
 #define _CRYPTO_CHACHA20_H
 
+#include <crypto/skcipher.h>
 #include <linux/types.h>
 #include <linux/crypto.h>
 
@@ -18,9 +19,8 @@ struct chacha20_ctx {
 
 void chacha20_block(u32 *state, void *stream);
 void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv);
-int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
+int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
 			   unsigned int keysize);
-int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
-			  struct scatterlist *src, unsigned int nbytes);
+int crypto_chacha20_crypt(struct skcipher_request *req);
 
 #endif