1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/*
  3 * Key-agreement Protocol Primitives (KPP)
  4 *
  5 * Copyright (c) 2016, Intel Corporation
  6 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
  7 */
  8
  9#ifndef _CRYPTO_KPP_
 10#define _CRYPTO_KPP_
 11
 12#include <linux/atomic.h>
 13#include <linux/container_of.h>
 14#include <linux/crypto.h>
 15#include <linux/slab.h>
 16
 17/**
 18 * struct kpp_request
 19 *
 20 * @base:	Common attributes for async crypto requests
 21 * @src:	Source data
 22 * @dst:	Destination data
 23 * @src_len:	Size of the input buffer
 24 * @dst_len:	Size of the output buffer. It needs to be at least
 25 *		as big as the expected result depending	on the operation
 26 *		After operation it will be updated with the actual size of the
 27 *		result. In case of error where the dst sgl size was insufficient,
 28 *		it will be updated to the size required for the operation.
 29 * @__ctx:	Start of private context data
 30 */
 31struct kpp_request {
 32	struct crypto_async_request base;
 33	struct scatterlist *src;
 34	struct scatterlist *dst;
 35	unsigned int src_len;
 36	unsigned int dst_len;
 37	void *__ctx[] CRYPTO_MINALIGN_ATTR;
 38};
 39
 40/**
 41 * struct crypto_kpp - user-instantiated object which encapsulate
 42 * algorithms and core processing logic
 43 *
 44 * @reqsize:		Request context size required by algorithm
 45 *			implementation
 46 * @base:	Common crypto API algorithm data structure
 47 */
 48struct crypto_kpp {
 49	unsigned int reqsize;
 50
 51	struct crypto_tfm base;
 52};
 53
 54/**
 55 * struct kpp_alg - generic key-agreement protocol primitives
 56 *
 57 * @set_secret:		Function invokes the protocol specific function to
 58 *			store the secret private key along with parameters.
 59 *			The implementation knows how to decode the buffer
 60 * @generate_public_key: Function generate the public key to be sent to the
 61 *			counterpart. In case of error, where output is not big
 62 *			enough req->dst_len will be updated to the size
 63 *			required
 64 * @compute_shared_secret: Function compute the shared secret as defined by
 65 *			the algorithm. The result is given back to the user.
 66 *			In case of error, where output is not big enough,
 67 *			req->dst_len will be updated to the size required
 68 * @max_size:		Function returns the size of the output buffer
 69 * @init:		Initialize the object. This is called only once at
 70 *			instantiation time. In case the cryptographic hardware
 71 *			needs to be initialized. Software fallback should be
 72 *			put in place here.
 73 * @exit:		Undo everything @init did.
 74 *
 75 * @base:		Common crypto API algorithm data structure
 76 */
 77struct kpp_alg {
 78	int (*set_secret)(struct crypto_kpp *tfm, const void *buffer,
 79			  unsigned int len);
 80	int (*generate_public_key)(struct kpp_request *req);
 81	int (*compute_shared_secret)(struct kpp_request *req);
 82
 83	unsigned int (*max_size)(struct crypto_kpp *tfm);
 84
 85	int (*init)(struct crypto_kpp *tfm);
 86	void (*exit)(struct crypto_kpp *tfm);
 87
 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
112int crypto_has_kpp(const char *alg_name, u32 type, u32 mask);
113
114static inline struct crypto_tfm *crypto_kpp_tfm(struct crypto_kpp *tfm)
115{
116	return &tfm->base;
117}
118
119static inline struct kpp_alg *__crypto_kpp_alg(struct crypto_alg *alg)
120{
121	return container_of(alg, struct kpp_alg, base);
122}
123
124static inline struct crypto_kpp *__crypto_kpp_tfm(struct crypto_tfm *tfm)
125{
126	return container_of(tfm, struct crypto_kpp, base);
127}
128
129static inline struct kpp_alg *crypto_kpp_alg(struct crypto_kpp *tfm)
130{
131	return __crypto_kpp_alg(crypto_kpp_tfm(tfm)->__crt_alg);
132}
133
134static inline unsigned int crypto_kpp_reqsize(struct crypto_kpp *tfm)
135{
136	return tfm->reqsize;
137}
138
139static inline void kpp_request_set_tfm(struct kpp_request *req,
140				       struct crypto_kpp *tfm)
141{
142	req->base.tfm = crypto_kpp_tfm(tfm);
143}
144
145static inline struct crypto_kpp *crypto_kpp_reqtfm(struct kpp_request *req)
146{
147	return __crypto_kpp_tfm(req->base.tfm);
148}
149
150static inline u32 crypto_kpp_get_flags(struct crypto_kpp *tfm)
151{
152	return crypto_tfm_get_flags(crypto_kpp_tfm(tfm));
153}
154
155static inline void crypto_kpp_set_flags(struct crypto_kpp *tfm, u32 flags)
156{
157	crypto_tfm_set_flags(crypto_kpp_tfm(tfm), flags);
158}
159
160/**
161 * crypto_free_kpp() - free KPP tfm handle
162 *
163 * @tfm: KPP tfm handle allocated with crypto_alloc_kpp()
164 *
165 * If @tfm is a NULL or error pointer, this function does nothing.
166 */
167static inline void crypto_free_kpp(struct crypto_kpp *tfm)
168{
169	crypto_destroy_tfm(tfm, crypto_kpp_tfm(tfm));
170}
171
172/**
173 * kpp_request_alloc() - allocates kpp request
174 *
175 * @tfm:	KPP tfm handle allocated with crypto_alloc_kpp()
176 * @gfp:	allocation flags
177 *
178 * Return: allocated handle in case of success or NULL in case of an error.
179 */
180static inline struct kpp_request *kpp_request_alloc(struct crypto_kpp *tfm,
181						    gfp_t gfp)
182{
183	struct kpp_request *req;
184
185	req = kmalloc(sizeof(*req) + crypto_kpp_reqsize(tfm), gfp);
186	if (likely(req))
187		kpp_request_set_tfm(req, tfm);
188
189	return req;
190}
191
192/**
193 * kpp_request_free() - zeroize and free kpp request
194 *
195 * @req:	request to free
196 */
197static inline void kpp_request_free(struct kpp_request *req)
198{
199	kfree_sensitive(req);
200}
201
202/**
203 * kpp_request_set_callback() - Sets an asynchronous callback.
204 *
205 * Callback will be called when an asynchronous operation on a given
206 * request is finished.
207 *
208 * @req:	request that the callback will be set for
209 * @flgs:	specify for instance if the operation may backlog
210 * @cmpl:	callback which will be called
211 * @data:	private data used by the caller
212 */
213static inline void kpp_request_set_callback(struct kpp_request *req,
214					    u32 flgs,
215					    crypto_completion_t cmpl,
216					    void *data)
217{
218	req->base.complete = cmpl;
219	req->base.data = data;
220	req->base.flags = flgs;
221}
222
223/**
224 * kpp_request_set_input() - Sets input buffer
225 *
226 * Sets parameters required by generate_public_key
227 *
228 * @req:	kpp request
229 * @input:	ptr to input scatter list
230 * @input_len:	size of the input scatter list
231 */
232static inline void kpp_request_set_input(struct kpp_request *req,
233					 struct scatterlist *input,
234					 unsigned int input_len)
235{
236	req->src = input;
237	req->src_len = input_len;
238}
239
240/**
241 * kpp_request_set_output() - Sets output buffer
242 *
243 * Sets parameters required by kpp operation
244 *
245 * @req:	kpp request
246 * @output:	ptr to output scatter list
247 * @output_len:	size of the output scatter list
248 */
249static inline void kpp_request_set_output(struct kpp_request *req,
250					  struct scatterlist *output,
251					  unsigned int output_len)
252{
253	req->dst = output;
254	req->dst_len = output_len;
255}
256
257enum {
258	CRYPTO_KPP_SECRET_TYPE_UNKNOWN,
259	CRYPTO_KPP_SECRET_TYPE_DH,
260	CRYPTO_KPP_SECRET_TYPE_ECDH,
261};
262
263/**
264 * struct kpp_secret - small header for packing secret buffer
265 *
266 * @type:	define type of secret. Each kpp type will define its own
267 * @len:	specify the len of the secret, include the header, that
268 *		follows the struct
269 */
270struct kpp_secret {
271	unsigned short type;
272	unsigned short len;
273};
274
275/**
276 * crypto_kpp_set_secret() - Invoke kpp operation
277 *
278 * Function invokes the specific kpp operation for a given alg.
279 *
280 * @tfm:	tfm handle
281 * @buffer:	Buffer holding the packet representation of the private
282 *		key. The structure of the packet key depends on the particular
283 *		KPP implementation. Packing and unpacking helpers are provided
284 *		for ECDH and DH (see the respective header files for those
285 *		implementations).
286 * @len:	Length of the packet private key buffer.
287 *
288 * Return: zero on success; error code in case of error
289 */
290static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm,
291					const void *buffer, unsigned int len)
292{
293	return crypto_kpp_alg(tfm)->set_secret(tfm, buffer, len);
294}
295
296/**
297 * crypto_kpp_generate_public_key() - Invoke kpp operation
298 *
299 * Function invokes the specific kpp operation for generating the public part
300 * for a given kpp algorithm.
301 *
302 * To generate a private key, the caller should use a random number generator.
303 * The output of the requested length serves as the private key.
304 *
305 * @req:	kpp key request
306 *
307 * Return: zero on success; error code in case of error
308 */
309static inline int crypto_kpp_generate_public_key(struct kpp_request *req)
310{
311	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
312
313	return crypto_kpp_alg(tfm)->generate_public_key(req);
314}
315
316/**
317 * crypto_kpp_compute_shared_secret() - Invoke kpp operation
318 *
319 * Function invokes the specific kpp operation for computing the shared secret
320 * for a given kpp algorithm.
321 *
322 * @req:	kpp key request
323 *
324 * Return: zero on success; error code in case of error
325 */
326static inline int crypto_kpp_compute_shared_secret(struct kpp_request *req)
327{
328	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
329
330	return crypto_kpp_alg(tfm)->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