crypto: skcipher - Add top-level skcipher interface

This patch introduces the crypto skcipher interface which aims
to replace both blkcipher and ablkcipher.

It's very similar to the existing ablkcipher interface.  The
main difference is the removal of the givcrypt interface.  In
order to make the transition easier for blkcipher users, there
is a helper SKCIPHER_REQUEST_ON_STACK which can be used to place
a request on the stack for synchronous transforms.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 246 insertions, 0 deletions

diff --git a/crypto/Makefile b/crypto/Makefile
index f6229ae..e2c5981 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_CRYPTO_AEAD2) += aead.o
 
 crypto_blkcipher-y := ablkcipher.o
 crypto_blkcipher-y += blkcipher.o
+crypto_blkcipher-y += skcipher.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += crypto_blkcipher.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += chainiv.o
 obj-$(CONFIG_CRYPTO_BLKCIPHER2) += eseqiv.o
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
new file mode 100644
index 0000000..dd5fc1b
--- /dev/null
+++ b/crypto/skcipher.c
@@ -0,0 +1,245 @@
+/*
+ * Symmetric key cipher operations.
+ *
+ * Generic encrypt/decrypt wrapper for ciphers, handles operations across
+ * multiple page boundaries by using temporary blocks.  In user context,
+ * the kernel is given a chance to schedule us once per page.
+ *
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * 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; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <crypto/internal/skcipher.h>
+#include <linux/bug.h>
+#include <linux/module.h>
+
+#include "internal.h"
+
+static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
+{
+	if (alg->cra_type == &crypto_blkcipher_type)
+		return sizeof(struct crypto_blkcipher *);
+
+	BUG_ON(alg->cra_type != &crypto_ablkcipher_type &&
+	       alg->cra_type != &crypto_givcipher_type);
+
+	return sizeof(struct crypto_ablkcipher *);
+}
+
+static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
+				     const u8 *key, unsigned int keylen)
+{
+	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_blkcipher *blkcipher = *ctx;
+	int err;
+
+	crypto_blkcipher_clear_flags(blkcipher, ~0);
+	crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
+					      CRYPTO_TFM_REQ_MASK);
+	err = crypto_blkcipher_setkey(blkcipher, key, keylen);
+	crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
+				       CRYPTO_TFM_RES_MASK);
+
+	return err;
+}
+
+static int skcipher_crypt_blkcipher(struct skcipher_request *req,
+				    int (*crypt)(struct blkcipher_desc *,
+						 struct scatterlist *,
+						 struct scatterlist *,
+						 unsigned int))
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
+	struct blkcipher_desc desc = {
+		.tfm = *ctx,
+		.info = req->iv,
+		.flags = req->base.flags,
+	};
+
+
+	return crypt(&desc, req->dst, req->src, req->cryptlen);
+}
+
+static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
+
+	return skcipher_crypt_blkcipher(req, alg->encrypt);
+}
+
+static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
+
+	return skcipher_crypt_blkcipher(req, alg->decrypt);
+}
+
+static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
+{
+	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_blkcipher(*ctx);
+}
+
+int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
+{
+	struct crypto_alg *calg = tfm->__crt_alg;
+	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
+	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
+	struct crypto_blkcipher *blkcipher;
+	struct crypto_tfm *btfm;
+
+	if (!crypto_mod_get(calg))
+		return -EAGAIN;
+
+	btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
+					CRYPTO_ALG_TYPE_MASK);
+	if (IS_ERR(btfm)) {
+		crypto_mod_put(calg);
+		return PTR_ERR(btfm);
+	}
+
+	blkcipher = __crypto_blkcipher_cast(btfm);
+	*ctx = blkcipher;
+	tfm->exit = crypto_exit_skcipher_ops_blkcipher;
+
+	skcipher->setkey = skcipher_setkey_blkcipher;
+	skcipher->encrypt = skcipher_encrypt_blkcipher;
+	skcipher->decrypt = skcipher_decrypt_blkcipher;
+
+	skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
+
+	return 0;
+}
+
+static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
+				      const u8 *key, unsigned int keylen)
+{
+	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_ablkcipher *ablkcipher = *ctx;
+	int err;
+
+	crypto_ablkcipher_clear_flags(ablkcipher, ~0);
+	crypto_ablkcipher_set_flags(ablkcipher,
+				    crypto_skcipher_get_flags(tfm) &
+				    CRYPTO_TFM_REQ_MASK);
+	err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
+	crypto_skcipher_set_flags(tfm,
+				  crypto_ablkcipher_get_flags(ablkcipher) &
+				  CRYPTO_TFM_RES_MASK);
+
+	return err;
+}
+
+static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
+				     int (*crypt)(struct ablkcipher_request *))
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
+	struct ablkcipher_request *subreq = skcipher_request_ctx(req);
+
+	ablkcipher_request_set_tfm(subreq, *ctx);
+	ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
+					req->base.complete, req->base.data);
+	ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
+				     req->iv);
+
+	return crypt(subreq);
+}
+
+static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
+
+	return skcipher_crypt_ablkcipher(req, alg->encrypt);
+}
+
+static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
+{
+	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
+	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
+
+	return skcipher_crypt_ablkcipher(req, alg->decrypt);
+}
+
+static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
+{
+	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_ablkcipher(*ctx);
+}
+
+int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
+{
+	struct crypto_alg *calg = tfm->__crt_alg;
+	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
+	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
+	struct crypto_ablkcipher *ablkcipher;
+	struct crypto_tfm *abtfm;
+
+	if (!crypto_mod_get(calg))
+		return -EAGAIN;
+
+	abtfm = __crypto_alloc_tfm(calg, 0, 0);
+	if (IS_ERR(abtfm)) {
+		crypto_mod_put(calg);
+		return PTR_ERR(abtfm);
+	}
+
+	ablkcipher = __crypto_ablkcipher_cast(abtfm);
+	*ctx = ablkcipher;
+	tfm->exit = crypto_exit_skcipher_ops_ablkcipher;
+
+	skcipher->setkey = skcipher_setkey_ablkcipher;
+	skcipher->encrypt = skcipher_encrypt_ablkcipher;
+	skcipher->decrypt = skcipher_decrypt_ablkcipher;
+
+	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
+	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
+			    sizeof(struct ablkcipher_request);
+
+	return 0;
+}
+
+static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
+{
+	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
+		return crypto_init_skcipher_ops_blkcipher(tfm);
+
+	BUG_ON(tfm->__crt_alg->cra_type != &crypto_ablkcipher_type &&
+	       tfm->__crt_alg->cra_type != &crypto_givcipher_type);
+
+	return crypto_init_skcipher_ops_ablkcipher(tfm);
+}
+
+static const struct crypto_type crypto_skcipher_type2 = {
+	.extsize = crypto_skcipher_extsize,
+	.init_tfm = crypto_skcipher_init_tfm,
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
+	.type = CRYPTO_ALG_TYPE_BLKCIPHER,
+	.tfmsize = offsetof(struct crypto_skcipher, base),
+};
+
+struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
+					      u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Symmetric key cipher type");