1/*
  2 * Key-agreement Protocol Primitives (KPP)
  3 *
  4 * Copyright (c) 2016, Intel Corporation
  5 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
  6 *
  7 * This program is free software; you can redistribute it and/or modify it
  8 * under the terms of the GNU General Public License as published by the Free
  9 * Software Foundation; either version 2 of the License, or (at your option)
 10 * any later version.
 11 *
 12 */
 13
 14#ifndef _CRYPTO_KPP_
 15#define _CRYPTO_KPP_
 16#include <linux/crypto.h>
 17
 18/**
 19 * struct kpp_request
 20 *
 21 * @base:	Common attributes for async crypto requests
 22 * @src:	Source data
 23 * @dst:	Destination data
 24 * @src_len:	Size of the input buffer
 25 * @dst_len:	Size of the output buffer. It needs to be at least
 26 *		as big as the expected result depending	on the operation
 27 *		After operation it will be updated with the actual size of the
 28 *		result. In case of error where the dst sgl size was insufficient,
 29 *		it will be updated to the size required for the operation.
 30 * @__ctx:	Start of private context data
 31 */
 32struct kpp_request {
 33	struct crypto_async_request base;
 34	struct scatterlist *src;
 35	struct scatterlist *dst;
 36	unsigned int src_len;
 37	unsigned int dst_len;
 38	void *__ctx[] CRYPTO_MINALIGN_ATTR;
 39};
 40
 41/**
 42 * struct crypto_kpp - user-instantiated object which encapsulate
 43 * algorithms and core processing logic
 44 *
 45 * @base:	Common crypto API algorithm data structure
 46 */
 47struct crypto_kpp {
 48	struct crypto_tfm base;
 49};
 50
 51/**
 52 * struct kpp_alg - generic key-agreement protocol primitives
 53 *
 54 * @set_secret:		Function invokes the protocol specific function to
 55 *			store the secret private key along with parameters.
 56 *			The implementation knows how to decode the buffer
 57 * @generate_public_key: Function generate the public key to be sent to the
 58 *			counterpart. In case of error, where output is not big
 59 *			enough req->dst_len will be updated to the size
 60 *			required
 61 * @compute_shared_secret: Function compute the shared secret as defined by
 62 *			the algorithm. The result is given back to the user.
 63 *			In case of error, where output is not big enough,
 64 *			req->dst_len will be updated to the size required
 65 * @max_size:		Function returns the size of the output buffer
 66 * @init:		Initialize the object. This is called only once at
 67 *			instantiation time. In case the cryptographic hardware
 68 *			needs to be initialized. Software fallback should be
 69 *			put in place here.
 70 * @exit:		Undo everything @init did.
 71 *
 72 * @reqsize:		Request context size required by algorithm
 73 *			implementation
 74 * @base:		Common crypto API algorithm data structure
 75 */
 76struct kpp_alg {
 77	int (*set_secret)(struct crypto_kpp *tfm, const void *buffer,
 78			  unsigned int len);
 79	int (*generate_public_key)(struct kpp_request *req);
 80	int (*compute_shared_secret)(struct kpp_request *req);
 81
 82	unsigned int (*max_size)(struct crypto_kpp *tfm);
 83
 84	int (*init)(struct crypto_kpp *tfm);
 85	void (*exit)(struct crypto_kpp *tfm);
 86
 87	unsigned int reqsize;
 88	struct crypto_alg base;
 89};
 90
 91/**
 92 * DOC: Generic Key-agreement Protocol Primitives API
 93 *
 94 * The KPP API is used with the algorithm type
 95 * CRYPTO_ALG_TYPE_KPP (listed as type "kpp" in /proc/crypto)
 96 */
 97
 98/**
 99 * crypto_alloc_kpp() - allocate KPP tfm handle
100 * @alg_name: is the name of the kpp algorithm (e.g. "dh", "ecdh")
101 * @type: specifies the type of the algorithm
102 * @mask: specifies the mask for the algorithm
103 *
104 * Allocate a handle for kpp algorithm. The returned struct crypto_kpp
105 * is required for any following API invocation
106 *
107 * Return: allocated handle in case of success; IS_ERR() is true in case of
108 *	   an error, PTR_ERR() returns the error code.
109 */
110struct crypto_kpp *crypto_alloc_kpp(const char *alg_name, u32 type, u32 mask);
111
112static inline struct crypto_tfm *crypto_kpp_tfm(struct crypto_kpp *tfm)
113{
114	return &tfm->base;
115}
116
117static inline struct kpp_alg *__crypto_kpp_alg(struct crypto_alg *alg)
118{
119	return container_of(alg, struct kpp_alg, base);
120}
121
122static inline struct crypto_kpp *__crypto_kpp_tfm(struct crypto_tfm *tfm)
123{
124	return container_of(tfm, struct crypto_kpp, base);
125}
126
127static inline struct kpp_alg *crypto_kpp_alg(struct crypto_kpp *tfm)
128{
129	return __crypto_kpp_alg(crypto_kpp_tfm(tfm)->__crt_alg);
130}
131
132static inline unsigned int crypto_kpp_reqsize(struct crypto_kpp *tfm)
133{
134	return crypto_kpp_alg(tfm)->reqsize;
135}
136
137static inline void kpp_request_set_tfm(struct kpp_request *req,
138				       struct crypto_kpp *tfm)
139{
140	req->base.tfm = crypto_kpp_tfm(tfm);
141}
142
143static inline struct crypto_kpp *crypto_kpp_reqtfm(struct kpp_request *req)
144{
145	return __crypto_kpp_tfm(req->base.tfm);
146}
147
148static inline u32 crypto_kpp_get_flags(struct crypto_kpp *tfm)
149{
150	return crypto_tfm_get_flags(crypto_kpp_tfm(tfm));
151}
152
153static inline void crypto_kpp_set_flags(struct crypto_kpp *tfm, u32 flags)
154{
155	crypto_tfm_set_flags(crypto_kpp_tfm(tfm), flags);
156}
157
158/**
159 * crypto_free_kpp() - free KPP tfm handle
160 *
161 * @tfm: KPP tfm handle allocated with crypto_alloc_kpp()
162 */
163static inline void crypto_free_kpp(struct crypto_kpp *tfm)
164{
165	crypto_destroy_tfm(tfm, crypto_kpp_tfm(tfm));
166}
167
168/**
169 * kpp_request_alloc() - allocates kpp request
170 *
171 * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
172 * @gfp:	allocation flags
173 *
174 * Return: allocated handle in case of success or NULL in case of an error.
175 */
176static inline struct kpp_request *kpp_request_alloc(struct crypto_kpp *tfm,
177						    gfp_t gfp)
178{
179	struct kpp_request *req;
180
181	req = kmalloc(sizeof(*req) + crypto_kpp_reqsize(tfm), gfp);
182	if (likely(req))
183		kpp_request_set_tfm(req, tfm);
184
185	return req;
186}
187
188/**
189 * kpp_request_free() - zeroize and free kpp request
190 *
191 * @req:	request to free
192 */
193static inline void kpp_request_free(struct kpp_request *req)
194{
195	kzfree(req);
196}
197
198/**
199 * kpp_request_set_callback() - Sets an asynchronous callback.
200 *
201 * Callback will be called when an asynchronous operation on a given
202 * request is finished.
203 *
204 * @req:	request that the callback will be set for
205 * @flgs:	specify for instance if the operation may backlog
206 * @cmpl:	callback which will be called
207 * @data:	private data used by the caller
208 */
209static inline void kpp_request_set_callback(struct kpp_request *req,
210					    u32 flgs,
211					    crypto_completion_t cmpl,
212					    void *data)
213{
214	req->base.complete = cmpl;
215	req->base.data = data;
216	req->base.flags = flgs;
217}
218
219/**
220 * kpp_request_set_input() - Sets input buffer
221 *
222 * Sets parameters required by generate_public_key
223 *
224 * @req:	kpp request
225 * @input:	ptr to input scatter list
226 * @input_len:	size of the input scatter list
227 */
228static inline void kpp_request_set_input(struct kpp_request *req,
229					 struct scatterlist *input,
230					 unsigned int input_len)
231{
232	req->src = input;
233	req->src_len = input_len;
234}
235
236/**
237 * kpp_request_set_output() - Sets output buffer
238 *
239 * Sets parameters required by kpp operation
240 *
241 * @req:	kpp request
242 * @output:	ptr to output scatter list
243 * @output_len:	size of the output scatter list
244 */
245static inline void kpp_request_set_output(struct kpp_request *req,
246					  struct scatterlist *output,
247					  unsigned int output_len)
248{
249	req->dst = output;
250	req->dst_len = output_len;
251}
252
253enum {
254	CRYPTO_KPP_SECRET_TYPE_UNKNOWN,
255	CRYPTO_KPP_SECRET_TYPE_DH,
256	CRYPTO_KPP_SECRET_TYPE_ECDH,
257};
258
259/**
260 * struct kpp_secret - small header for packing secret buffer
261 *
262 * @type:	define type of secret. Each kpp type will define its own
263 * @len:	specify the len of the secret, include the header, that
264 *		follows the struct
265 */
266struct kpp_secret {
267	unsigned short type;
268	unsigned short len;
269};
270
271/**
272 * crypto_kpp_set_secret() - Invoke kpp operation
273 *
274 * Function invokes the specific kpp operation for a given alg.
275 *
276 * @tfm:	tfm handle
277 * @buffer:	Buffer holding the packet representation of the private
278 *		key. The structure of the packet key depends on the particular
279 *		KPP implementation. Packing and unpacking helpers are provided
280 *		for ECDH and DH (see the respective header files for those
281 *		implementations).
282 * @len:	Length of the packet private key buffer.
283 *
284 * Return: zero on success; error code in case of error
285 */
286static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm,
287					const void *buffer, unsigned int len)
288{
289	struct kpp_alg *alg = crypto_kpp_alg(tfm);
290
291	return alg->set_secret(tfm, buffer, len);
292}
293
294/**
295 * crypto_kpp_generate_public_key() - Invoke kpp operation
296 *
297 * Function invokes the specific kpp operation for generating the public part
298 * for a given kpp algorithm.
299 *
300 * To generate a private key, the caller should use a random number generator.
301 * The output of the requested length serves as the private key.
302 *
303 * @req:	kpp key request
304 *
305 * Return: zero on success; error code in case of error
306 */
307static inline int crypto_kpp_generate_public_key(struct kpp_request *req)
308{
309	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
310	struct kpp_alg *alg = crypto_kpp_alg(tfm);
311
312	return alg->generate_public_key(req);
313}
314
315/**
316 * crypto_kpp_compute_shared_secret() - Invoke kpp operation
317 *
318 * Function invokes the specific kpp operation for computing the shared secret
319 * for a given kpp algorithm.
320 *
321 * @req:	kpp key request
322 *
323 * Return: zero on success; error code in case of error
324 */
325static inline int crypto_kpp_compute_shared_secret(struct kpp_request *req)
326{
327	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
328	struct kpp_alg *alg = crypto_kpp_alg(tfm);
329
330	return alg->compute_shared_secret(req);
331}
332
333/**
334 * crypto_kpp_maxsize() - Get len for output buffer
335 *
336 * Function returns the output buffer size required for a given key.
337 * Function assumes that the key is already set in the transformation. If this
338 * function is called without a setkey or with a failed setkey, you will end up
339 * in a NULL dereference.
340 *
341 * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
342 */
343static inline unsigned int crypto_kpp_maxsize(struct crypto_kpp *tfm)
344{
345	struct kpp_alg *alg = crypto_kpp_alg(tfm);
346
347	return alg->max_size(tfm);
348}
349
350#endif