crypto: kpp - Key-agreement Protocol Primitives API (KPP)

Add key-agreement protocol primitives (kpp) API which allows to
implement primitives required by protocols such as DH and ECDH.
The API is composed mainly by the following functions
 * set_secret() - It allows the user to set his secret, also
   referred to as his private key, along with the parameters
   known to both parties involved in the key-agreement session.
 * generate_public_key() - It generates the public key to be sent to
   the other counterpart involved in the key-agreement session. The
   function has to be called after set_params() and set_secret()
 * generate_secret() - It generates the shared secret for the session

Other functions such as init() and exit() are provided for allowing
cryptographic hardware to be inizialized properly before use

Signed-off-by: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 328 insertions, 0 deletions

diff --git a/include/crypto/kpp.h b/include/crypto/kpp.h
new file mode 100644
index 000000000000..4fa897f3366b
--- /dev/null
+++ b/include/crypto/kpp.h
@@ -0,0 +1,328 @@
+/*
+ * Key-agreement Protocol Primitives (KPP)
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ *
+ * 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.
+ *
+ */
+
+#ifndef _CRYPTO_KPP_
+#define _CRYPTO_KPP_
+#include <linux/crypto.h>
+
+/**
+ * struct kpp_request
+ *
+ * @base:	Common attributes for async crypto requests
+ * @src:	Source data
+ * @dst:	Destination data
+ * @src_len:	Size of the input buffer
+ * @dst_len:	Size of the output buffer. It needs to be at least
+ *		as big as the expected result depending	on the operation
+ *		After operation it will be updated with the actual size of the
+ *		result. In case of error where the dst sgl size was insufficient,
+ *		it will be updated to the size required for the operation.
+ * @__ctx:	Start of private context data
+ */
+struct kpp_request {
+	struct crypto_async_request base;
+	struct scatterlist *src;
+	struct scatterlist *dst;
+	unsigned int src_len;
+	unsigned int dst_len;
+	void *__ctx[] CRYPTO_MINALIGN_ATTR;
+};
+
+/**
+ * struct crypto_kpp - user-instantiated object which encapsulate
+ * algorithms and core processing logic
+ *
+ * @base:	Common crypto API algorithm data structure
+ */
+struct crypto_kpp {
+	struct crypto_tfm base;
+};
+
+/**
+ * struct kpp_alg - generic key-agreement protocol primitives
+ *
+ * @set_secret:		Function invokes the protocol specific function to
+ *			store the secret private key along with parameters.
+ *			The implementation knows how to decode thie buffer
+ * @generate_public_key: Function generate the public key to be sent to the
+ *			counterpart. In case of error, where output is not big
+ *			enough req->dst_len will be updated to the size
+ *			required
+ * @compute_shared_secret: Function compute the shared secret as defined by
+ *			the algorithm. The result is given back to the user.
+ *			In case of error, where output is not big enough,
+ *			req->dst_len will be updated to the size required
+ * @max_size:		Function returns the size of the output buffer
+ * @init:		Initialize the object. This is called only once at
+ *			instantiation time. In case the cryptographic hardware
+ *			needs to be initialized. Software fallback should be
+ *			put in place here.
+ * @exit:		Undo everything @init did.
+ *
+ * @reqsize:		Request context size required by algorithm
+ *			implementation
+ * @base		Common crypto API algorithm data structure
+ */
+struct kpp_alg {
+	int (*set_secret)(struct crypto_kpp *tfm, void *buffer,
+			  unsigned int len);
+	int (*generate_public_key)(struct kpp_request *req);
+	int (*compute_shared_secret)(struct kpp_request *req);
+
+	int (*max_size)(struct crypto_kpp *tfm);
+
+	int (*init)(struct crypto_kpp *tfm);
+	void (*exit)(struct crypto_kpp *tfm);
+
+	unsigned int reqsize;
+	struct crypto_alg base;
+};
+
+/**
+ * DOC: Generic Key-agreement Protocol Primitevs API
+ *
+ * The KPP API is used with the algorithm type
+ * CRYPTO_ALG_TYPE_KPP (listed as type "kpp" in /proc/crypto)
+ */
+
+/**
+ * crypto_alloc_kpp() - allocate KPP tfm handle
+ * @alg_name: is the name of the kpp algorithm (e.g. "dh", "ecdh")
+ * @type: specifies the type of the algorithm
+ * @mask: specifies the mask for the algorithm
+ *
+ * Allocate a handle for kpp algorithm. The returned struct crypto_kpp
+ * is requeried for any following API invocation
+ *
+ * Return: allocated handle in case of success; IS_ERR() is true in case of
+ *	   an error, PTR_ERR() returns the error code.
+ */
+struct crypto_kpp *crypto_alloc_kpp(const char *alg_name, u32 type, u32 mask);
+
+static inline struct crypto_tfm *crypto_kpp_tfm(struct crypto_kpp *tfm)
+{
+	return &tfm->base;
+}
+
+static inline struct kpp_alg *__crypto_kpp_alg(struct crypto_alg *alg)
+{
+	return container_of(alg, struct kpp_alg, base);
+}
+
+static inline struct crypto_kpp *__crypto_kpp_tfm(struct crypto_tfm *tfm)
+{
+	return container_of(tfm, struct crypto_kpp, base);
+}
+
+static inline struct kpp_alg *crypto_kpp_alg(struct crypto_kpp *tfm)
+{
+	return __crypto_kpp_alg(crypto_kpp_tfm(tfm)->__crt_alg);
+}
+
+static inline unsigned int crypto_kpp_reqsize(struct crypto_kpp *tfm)
+{
+	return crypto_kpp_alg(tfm)->reqsize;
+}
+
+static inline void kpp_request_set_tfm(struct kpp_request *req,
+				       struct crypto_kpp *tfm)
+{
+	req->base.tfm = crypto_kpp_tfm(tfm);
+}
+
+static inline struct crypto_kpp *crypto_kpp_reqtfm(struct kpp_request *req)
+{
+	return __crypto_kpp_tfm(req->base.tfm);
+}
+
+/**
+ * crypto_free_kpp() - free KPP tfm handle
+ *
+ * @tfm: KPP tfm handle allocated with crypto_alloc_kpp()
+ */
+static inline void crypto_free_kpp(struct crypto_kpp *tfm)
+{
+	crypto_destroy_tfm(tfm, crypto_kpp_tfm(tfm));
+}
+
+/**
+ * kpp_request_alloc() - allocates kpp request
+ *
+ * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
+ * @gfp:	allocation flags
+ *
+ * Return: allocated handle in case of success or NULL in case of an error.
+ */
+static inline struct kpp_request *kpp_request_alloc(struct crypto_kpp *tfm,
+						    gfp_t gfp)
+{
+	struct kpp_request *req;
+
+	req = kmalloc(sizeof(*req) + crypto_kpp_reqsize(tfm), gfp);
+	if (likely(req))
+		kpp_request_set_tfm(req, tfm);
+
+	return req;
+}
+
+/**
+ * kpp_request_free() - zeroize and free kpp request
+ *
+ * @req:	request to free
+ */
+static inline void kpp_request_free(struct kpp_request *req)
+{
+	kzfree(req);
+}
+
+/**
+ * kpp_request_set_callback() - Sets an asynchronous callback.
+ *
+ * Callback will be called when an asynchronous operation on a given
+ * request is finished.
+ *
+ * @req:	request that the callback will be set for
+ * @flgs:	specify for instance if the operation may backlog
+ * @cmpl:	callback which will be called
+ * @data:	private data used by the caller
+ */
+static inline void kpp_request_set_callback(struct kpp_request *req,
+					    u32 flgs,
+					    crypto_completion_t cmpl,
+					    void *data)
+{
+	req->base.complete = cmpl;
+	req->base.data = data;
+	req->base.flags = flgs;
+}
+
+/**
+ * kpp_request_set_input() - Sets input buffer
+ *
+ * Sets parameters required by generate_public_key
+ *
+ * @req:	kpp request
+ * @input:	ptr to input scatter list
+ * @input_len:	size of the input scatter list
+ */
+static inline void kpp_request_set_input(struct kpp_request *req,
+					 struct scatterlist *input,
+					 unsigned int input_len)
+{
+	req->src = input;
+	req->src_len = input_len;
+}
+
+/**
+ * kpp_request_set_output() - Sets output buffer
+ *
+ * Sets parameters required by kpp operation
+ *
+ * @req:	kpp request
+ * @output:	ptr to output scatter list
+ * @output_len:	size of the output scatter list
+ */
+static inline void kpp_request_set_output(struct kpp_request *req,
+					  struct scatterlist *output,
+					  unsigned int output_len)
+{
+	req->dst = output;
+	req->dst_len = output_len;
+}
+
+enum {
+	CRYPTO_KPP_SECRET_TYPE_UNKNOWN,
+};
+
+/**
+ * struct kpp_secret - small header for packing secret buffer
+ *
+ * @type:	define type of secret. Each kpp type will define its own
+ * @len:	specify the len of the secret, include the header, that
+ *		follows the struct
+ */
+struct kpp_secret {
+	unsigned short type;
+	unsigned short len;
+};
+
+/**
+ * crypto_kpp_set_secret() - Invoke kpp operation
+ *
+ * Function invokes the specific kpp operation for a given alg.
+ *
+ * @tfm:	tfm handle
+ *
+ * Return: zero on success; error code in case of error
+ */
+static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm, void *buffer,
+					unsigned int len)
+{
+	struct kpp_alg *alg = crypto_kpp_alg(tfm);
+
+	return alg->set_secret(tfm, buffer, len);
+}
+
+/**
+ * crypto_kpp_generate_public_key() - Invoke kpp operation
+ *
+ * Function invokes the specific kpp operation for generating the public part
+ * for a given kpp algorithm
+ *
+ * @req:	kpp key request
+ *
+ * Return: zero on success; error code in case of error
+ */
+static inline int crypto_kpp_generate_public_key(struct kpp_request *req)
+{
+	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+	struct kpp_alg *alg = crypto_kpp_alg(tfm);
+
+	return alg->generate_public_key(req);
+}
+
+/**
+ * crypto_kpp_compute_shared_secret() - Invoke kpp operation
+ *
+ * Function invokes the specific kpp operation for computing the shared secret
+ * for a given kpp algorithm.
+ *
+ * @req:	kpp key request
+ *
+ * Return: zero on success; error code in case of error
+ */
+static inline int crypto_kpp_compute_shared_secret(struct kpp_request *req)
+{
+	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+	struct kpp_alg *alg = crypto_kpp_alg(tfm);
+
+	return alg->compute_shared_secret(req);
+}
+
+/**
+ * crypto_kpp_maxsize() - Get len for output buffer
+ *
+ * Function returns the output buffer size required
+ *
+ * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
+ *
+ * Return: minimum len for output buffer or error code if key hasn't been set
+ */
+static inline int crypto_kpp_maxsize(struct crypto_kpp *tfm)
+{
+	struct kpp_alg *alg = crypto_kpp_alg(tfm);
+
+	return alg->max_size(tfm);
+}
+
+#endif