1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Intel Keem Bay OCS ECC Crypto Driver.
4  *
5  * Copyright (C) 2019-2021 Intel Corporation
6  */
7 
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 
10 #include <crypto/ecc_curve.h>
11 #include <crypto/ecdh.h>
12 #include <crypto/engine.h>
13 #include <crypto/internal/ecc.h>
14 #include <crypto/internal/kpp.h>
15 #include <crypto/kpp.h>
16 #include <crypto/rng.h>
17 #include <linux/clk.h>
18 #include <linux/completion.h>
19 #include <linux/err.h>
20 #include <linux/fips.h>
21 #include <linux/interrupt.h>
22 #include <linux/io.h>
23 #include <linux/iopoll.h>
24 #include <linux/irq.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/of.h>
28 #include <linux/platform_device.h>
29 #include <linux/scatterlist.h>
30 #include <linux/string.h>
31 
32 #define DRV_NAME			"keembay-ocs-ecc"
33 
34 #define KMB_OCS_ECC_PRIORITY		350
35 
36 #define HW_OFFS_OCS_ECC_COMMAND		0x00000000
37 #define HW_OFFS_OCS_ECC_STATUS		0x00000004
38 #define HW_OFFS_OCS_ECC_DATA_IN		0x00000080
39 #define HW_OFFS_OCS_ECC_CX_DATA_OUT	0x00000100
40 #define HW_OFFS_OCS_ECC_CY_DATA_OUT	0x00000180
41 #define HW_OFFS_OCS_ECC_ISR		0x00000400
42 #define HW_OFFS_OCS_ECC_IER		0x00000404
43 
44 #define HW_OCS_ECC_ISR_INT_STATUS_DONE	BIT(0)
45 #define HW_OCS_ECC_COMMAND_INS_BP	BIT(0)
46 
47 #define HW_OCS_ECC_COMMAND_START_VAL	BIT(0)
48 
49 #define OCS_ECC_OP_SIZE_384		BIT(8)
50 #define OCS_ECC_OP_SIZE_256		0
51 
52 /* ECC Instruction : for ECC_COMMAND */
53 #define OCS_ECC_INST_WRITE_AX		(0x1 << HW_OCS_ECC_COMMAND_INS_BP)
54 #define OCS_ECC_INST_WRITE_AY		(0x2 << HW_OCS_ECC_COMMAND_INS_BP)
55 #define OCS_ECC_INST_WRITE_BX_D		(0x3 << HW_OCS_ECC_COMMAND_INS_BP)
56 #define OCS_ECC_INST_WRITE_BY_L		(0x4 << HW_OCS_ECC_COMMAND_INS_BP)
57 #define OCS_ECC_INST_WRITE_P		(0x5 << HW_OCS_ECC_COMMAND_INS_BP)
58 #define OCS_ECC_INST_WRITE_A		(0x6 << HW_OCS_ECC_COMMAND_INS_BP)
59 #define OCS_ECC_INST_CALC_D_IDX_A	(0x8 << HW_OCS_ECC_COMMAND_INS_BP)
60 #define OCS_ECC_INST_CALC_A_POW_B_MODP	(0xB << HW_OCS_ECC_COMMAND_INS_BP)
61 #define OCS_ECC_INST_CALC_A_MUL_B_MODP	(0xC  << HW_OCS_ECC_COMMAND_INS_BP)
62 #define OCS_ECC_INST_CALC_A_ADD_B_MODP	(0xD << HW_OCS_ECC_COMMAND_INS_BP)
63 
64 #define ECC_ENABLE_INTR			1
65 
66 #define POLL_USEC			100
67 #define TIMEOUT_USEC			10000
68 
69 #define KMB_ECC_VLI_MAX_DIGITS		ECC_CURVE_NIST_P384_DIGITS
70 #define KMB_ECC_VLI_MAX_BYTES		(KMB_ECC_VLI_MAX_DIGITS \
71 					 << ECC_DIGITS_TO_BYTES_SHIFT)
72 
73 #define POW_CUBE			3
74 
75 /**
76  * struct ocs_ecc_dev - ECC device context
77  * @list: List of device contexts
78  * @dev: OCS ECC device
79  * @base_reg: IO base address of OCS ECC
80  * @engine: Crypto engine for the device
81  * @irq_done: IRQ done completion.
82  * @irq: IRQ number
83  */
84 struct ocs_ecc_dev {
85 	struct list_head list;
86 	struct device *dev;
87 	void __iomem *base_reg;
88 	struct crypto_engine *engine;
89 	struct completion irq_done;
90 	int irq;
91 };
92 
93 /**
94  * struct ocs_ecc_ctx - Transformation context.
95  * @ecc_dev:	 The ECC driver associated with this context.
96  * @curve:	 The elliptic curve used by this transformation.
97  * @private_key: The private key.
98  */
99 struct ocs_ecc_ctx {
100 	struct ocs_ecc_dev *ecc_dev;
101 	const struct ecc_curve *curve;
102 	u64 private_key[KMB_ECC_VLI_MAX_DIGITS];
103 };
104 
105 /* Driver data. */
106 struct ocs_ecc_drv {
107 	struct list_head dev_list;
108 	spinlock_t lock;	/* Protects dev_list. */
109 };
110 
111 /* Global variable holding the list of OCS ECC devices (only one expected). */
112 static struct ocs_ecc_drv ocs_ecc = {
113 	.dev_list = LIST_HEAD_INIT(ocs_ecc.dev_list),
114 	.lock = __SPIN_LOCK_UNLOCKED(ocs_ecc.lock),
115 };
116 
117 /* Get OCS ECC tfm context from kpp_request. */
kmb_ocs_ecc_tctx(struct kpp_request * req)118 static inline struct ocs_ecc_ctx *kmb_ocs_ecc_tctx(struct kpp_request *req)
119 {
120 	return kpp_tfm_ctx(crypto_kpp_reqtfm(req));
121 }
122 
123 /* Converts number of digits to number of bytes. */
digits_to_bytes(unsigned int n)124 static inline unsigned int digits_to_bytes(unsigned int n)
125 {
126 	return n << ECC_DIGITS_TO_BYTES_SHIFT;
127 }
128 
129 /*
130  * Wait for ECC idle i.e when an operation (other than write operations)
131  * is done.
132  */
ocs_ecc_wait_idle(struct ocs_ecc_dev * dev)133 static inline int ocs_ecc_wait_idle(struct ocs_ecc_dev *dev)
134 {
135 	u32 value;
136 
137 	return readl_poll_timeout((dev->base_reg + HW_OFFS_OCS_ECC_STATUS),
138 				  value,
139 				  !(value & HW_OCS_ECC_ISR_INT_STATUS_DONE),
140 				  POLL_USEC, TIMEOUT_USEC);
141 }
142 
ocs_ecc_cmd_start(struct ocs_ecc_dev * ecc_dev,u32 op_size)143 static void ocs_ecc_cmd_start(struct ocs_ecc_dev *ecc_dev, u32 op_size)
144 {
145 	iowrite32(op_size | HW_OCS_ECC_COMMAND_START_VAL,
146 		  ecc_dev->base_reg + HW_OFFS_OCS_ECC_COMMAND);
147 }
148 
149 /* Direct write of u32 buffer to ECC engine with associated instruction. */
ocs_ecc_write_cmd_and_data(struct ocs_ecc_dev * dev,u32 op_size,u32 inst,const void * data_in,size_t data_size)150 static void ocs_ecc_write_cmd_and_data(struct ocs_ecc_dev *dev,
151 				       u32 op_size,
152 				       u32 inst,
153 				       const void *data_in,
154 				       size_t data_size)
155 {
156 	iowrite32(op_size | inst, dev->base_reg + HW_OFFS_OCS_ECC_COMMAND);
157 
158 	/* MMIO Write src uint32 to dst. */
159 	memcpy_toio(dev->base_reg + HW_OFFS_OCS_ECC_DATA_IN, data_in,
160 		    data_size);
161 }
162 
163 /* Start OCS ECC operation and wait for its completion. */
ocs_ecc_trigger_op(struct ocs_ecc_dev * ecc_dev,u32 op_size,u32 inst)164 static int ocs_ecc_trigger_op(struct ocs_ecc_dev *ecc_dev, u32 op_size,
165 			      u32 inst)
166 {
167 	reinit_completion(&ecc_dev->irq_done);
168 
169 	iowrite32(ECC_ENABLE_INTR, ecc_dev->base_reg + HW_OFFS_OCS_ECC_IER);
170 	iowrite32(op_size | inst, ecc_dev->base_reg + HW_OFFS_OCS_ECC_COMMAND);
171 
172 	return wait_for_completion_interruptible(&ecc_dev->irq_done);
173 }
174 
175 /**
176  * ocs_ecc_read_cx_out() - Read the CX data output buffer.
177  * @dev:	The OCS ECC device to read from.
178  * @cx_out:	The buffer where to store the CX value. Must be at least
179  *		@byte_count byte long.
180  * @byte_count:	The amount of data to read.
181  */
ocs_ecc_read_cx_out(struct ocs_ecc_dev * dev,void * cx_out,size_t byte_count)182 static inline void ocs_ecc_read_cx_out(struct ocs_ecc_dev *dev, void *cx_out,
183 				       size_t byte_count)
184 {
185 	memcpy_fromio(cx_out, dev->base_reg + HW_OFFS_OCS_ECC_CX_DATA_OUT,
186 		      byte_count);
187 }
188 
189 /**
190  * ocs_ecc_read_cy_out() - Read the CX data output buffer.
191  * @dev:	The OCS ECC device to read from.
192  * @cy_out:	The buffer where to store the CY value. Must be at least
193  *		@byte_count byte long.
194  * @byte_count:	The amount of data to read.
195  */
ocs_ecc_read_cy_out(struct ocs_ecc_dev * dev,void * cy_out,size_t byte_count)196 static inline void ocs_ecc_read_cy_out(struct ocs_ecc_dev *dev, void *cy_out,
197 				       size_t byte_count)
198 {
199 	memcpy_fromio(cy_out, dev->base_reg + HW_OFFS_OCS_ECC_CY_DATA_OUT,
200 		      byte_count);
201 }
202 
kmb_ocs_ecc_find_dev(struct ocs_ecc_ctx * tctx)203 static struct ocs_ecc_dev *kmb_ocs_ecc_find_dev(struct ocs_ecc_ctx *tctx)
204 {
205 	if (tctx->ecc_dev)
206 		return tctx->ecc_dev;
207 
208 	spin_lock(&ocs_ecc.lock);
209 
210 	/* Only a single OCS device available. */
211 	tctx->ecc_dev = list_first_entry(&ocs_ecc.dev_list, struct ocs_ecc_dev,
212 					 list);
213 
214 	spin_unlock(&ocs_ecc.lock);
215 
216 	return tctx->ecc_dev;
217 }
218 
219 /* Do point multiplication using OCS ECC HW. */
kmb_ecc_point_mult(struct ocs_ecc_dev * ecc_dev,struct ecc_point * result,const struct ecc_point * point,u64 * scalar,const struct ecc_curve * curve)220 static int kmb_ecc_point_mult(struct ocs_ecc_dev *ecc_dev,
221 			      struct ecc_point *result,
222 			      const struct ecc_point *point,
223 			      u64 *scalar,
224 			      const struct ecc_curve *curve)
225 {
226 	u8 sca[KMB_ECC_VLI_MAX_BYTES]; /* Use the maximum data size. */
227 	u32 op_size = (curve->g.ndigits > ECC_CURVE_NIST_P256_DIGITS) ?
228 		      OCS_ECC_OP_SIZE_384 : OCS_ECC_OP_SIZE_256;
229 	size_t nbytes = digits_to_bytes(curve->g.ndigits);
230 	int rc = 0;
231 
232 	/* Generate random nbytes for Simple and Differential SCA protection. */
233 	rc = crypto_get_default_rng();
234 	if (rc)
235 		return rc;
236 
237 	rc = crypto_rng_get_bytes(crypto_default_rng, sca, nbytes);
238 	crypto_put_default_rng();
239 	if (rc)
240 		return rc;
241 
242 	/* Wait engine to be idle before starting new operation. */
243 	rc = ocs_ecc_wait_idle(ecc_dev);
244 	if (rc)
245 		return rc;
246 
247 	/* Send ecc_start pulse as well as indicating operation size. */
248 	ocs_ecc_cmd_start(ecc_dev, op_size);
249 
250 	/* Write ax param; Base point (Gx). */
251 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_AX,
252 				   point->x, nbytes);
253 
254 	/* Write ay param; Base point (Gy). */
255 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_AY,
256 				   point->y, nbytes);
257 
258 	/*
259 	 * Write the private key into DATA_IN reg.
260 	 *
261 	 * Since DATA_IN register is used to write different values during the
262 	 * computation private Key value is overwritten with
263 	 * side-channel-resistance value.
264 	 */
265 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_BX_D,
266 				   scalar, nbytes);
267 
268 	/* Write operand by/l. */
269 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_BY_L,
270 				   sca, nbytes);
271 	memzero_explicit(sca, sizeof(sca));
272 
273 	/* Write p = curve prime(GF modulus). */
274 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_P,
275 				   curve->p, nbytes);
276 
277 	/* Write a = curve coefficient. */
278 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_A,
279 				   curve->a, nbytes);
280 
281 	/* Make hardware perform the multiplication. */
282 	rc = ocs_ecc_trigger_op(ecc_dev, op_size, OCS_ECC_INST_CALC_D_IDX_A);
283 	if (rc)
284 		return rc;
285 
286 	/* Read result. */
287 	ocs_ecc_read_cx_out(ecc_dev, result->x, nbytes);
288 	ocs_ecc_read_cy_out(ecc_dev, result->y, nbytes);
289 
290 	return 0;
291 }
292 
293 /**
294  * kmb_ecc_do_scalar_op() - Perform Scalar operation using OCS ECC HW.
295  * @ecc_dev:	The OCS ECC device to use.
296  * @scalar_out:	Where to store the output scalar.
297  * @scalar_a:	Input scalar operand 'a'.
298  * @scalar_b:	Input scalar operand 'b'
299  * @curve:	The curve on which the operation is performed.
300  * @ndigits:	The size of the operands (in digits).
301  * @inst:	The operation to perform (as an OCS ECC instruction).
302  *
303  * Return:	0 on success, negative error code otherwise.
304  */
kmb_ecc_do_scalar_op(struct ocs_ecc_dev * ecc_dev,u64 * scalar_out,const u64 * scalar_a,const u64 * scalar_b,const struct ecc_curve * curve,unsigned int ndigits,const u32 inst)305 static int kmb_ecc_do_scalar_op(struct ocs_ecc_dev *ecc_dev, u64 *scalar_out,
306 				const u64 *scalar_a, const u64 *scalar_b,
307 				const struct ecc_curve *curve,
308 				unsigned int ndigits, const u32 inst)
309 {
310 	u32 op_size = (ndigits > ECC_CURVE_NIST_P256_DIGITS) ?
311 		      OCS_ECC_OP_SIZE_384 : OCS_ECC_OP_SIZE_256;
312 	size_t nbytes = digits_to_bytes(ndigits);
313 	int rc;
314 
315 	/* Wait engine to be idle before starting new operation. */
316 	rc = ocs_ecc_wait_idle(ecc_dev);
317 	if (rc)
318 		return rc;
319 
320 	/* Send ecc_start pulse as well as indicating operation size. */
321 	ocs_ecc_cmd_start(ecc_dev, op_size);
322 
323 	/* Write ax param (Base point (Gx).*/
324 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_AX,
325 				   scalar_a, nbytes);
326 
327 	/* Write ay param Base point (Gy).*/
328 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_AY,
329 				   scalar_b, nbytes);
330 
331 	/* Write p = curve prime(GF modulus).*/
332 	ocs_ecc_write_cmd_and_data(ecc_dev, op_size, OCS_ECC_INST_WRITE_P,
333 				   curve->p, nbytes);
334 
335 	/* Give instruction A.B or A+B to ECC engine. */
336 	rc = ocs_ecc_trigger_op(ecc_dev, op_size, inst);
337 	if (rc)
338 		return rc;
339 
340 	ocs_ecc_read_cx_out(ecc_dev, scalar_out, nbytes);
341 
342 	if (vli_is_zero(scalar_out, ndigits))
343 		return -EINVAL;
344 
345 	return 0;
346 }
347 
348 /* SP800-56A section 5.6.2.3.4 partial verification: ephemeral keys only */
kmb_ocs_ecc_is_pubkey_valid_partial(struct ocs_ecc_dev * ecc_dev,const struct ecc_curve * curve,struct ecc_point * pk)349 static int kmb_ocs_ecc_is_pubkey_valid_partial(struct ocs_ecc_dev *ecc_dev,
350 					       const struct ecc_curve *curve,
351 					       struct ecc_point *pk)
352 {
353 	u64 xxx[KMB_ECC_VLI_MAX_DIGITS] = { 0 };
354 	u64 yy[KMB_ECC_VLI_MAX_DIGITS] = { 0 };
355 	u64 w[KMB_ECC_VLI_MAX_DIGITS] = { 0 };
356 	int rc;
357 
358 	if (WARN_ON(pk->ndigits != curve->g.ndigits))
359 		return -EINVAL;
360 
361 	/* Check 1: Verify key is not the zero point. */
362 	if (ecc_point_is_zero(pk))
363 		return -EINVAL;
364 
365 	/* Check 2: Verify key is in the range [0, p-1]. */
366 	if (vli_cmp(curve->p, pk->x, pk->ndigits) != 1)
367 		return -EINVAL;
368 
369 	if (vli_cmp(curve->p, pk->y, pk->ndigits) != 1)
370 		return -EINVAL;
371 
372 	/* Check 3: Verify that y^2 == (x^3 + a·x + b) mod p */
373 
374 	 /* y^2 */
375 	/* Compute y^2 -> store in yy */
376 	rc = kmb_ecc_do_scalar_op(ecc_dev, yy, pk->y, pk->y, curve, pk->ndigits,
377 				  OCS_ECC_INST_CALC_A_MUL_B_MODP);
378 	if (rc)
379 		goto exit;
380 
381 	/* x^3 */
382 	/* Assigning w = 3, used for calculating x^3. */
383 	w[0] = POW_CUBE;
384 	/* Load the next stage.*/
385 	rc = kmb_ecc_do_scalar_op(ecc_dev, xxx, pk->x, w, curve, pk->ndigits,
386 				  OCS_ECC_INST_CALC_A_POW_B_MODP);
387 	if (rc)
388 		goto exit;
389 
390 	/* Do a*x -> store in w. */
391 	rc = kmb_ecc_do_scalar_op(ecc_dev, w, curve->a, pk->x, curve,
392 				  pk->ndigits,
393 				  OCS_ECC_INST_CALC_A_MUL_B_MODP);
394 	if (rc)
395 		goto exit;
396 
397 	/* Do ax + b == w + b; store in w. */
398 	rc = kmb_ecc_do_scalar_op(ecc_dev, w, w, curve->b, curve,
399 				  pk->ndigits,
400 				  OCS_ECC_INST_CALC_A_ADD_B_MODP);
401 	if (rc)
402 		goto exit;
403 
404 	/* x^3 + ax + b == x^3 + w -> store in w. */
405 	rc = kmb_ecc_do_scalar_op(ecc_dev, w, xxx, w, curve, pk->ndigits,
406 				  OCS_ECC_INST_CALC_A_ADD_B_MODP);
407 	if (rc)
408 		goto exit;
409 
410 	/* Compare y^2 == x^3 + a·x + b. */
411 	rc = vli_cmp(yy, w, pk->ndigits);
412 	if (rc)
413 		rc = -EINVAL;
414 
415 exit:
416 	memzero_explicit(xxx, sizeof(xxx));
417 	memzero_explicit(yy, sizeof(yy));
418 	memzero_explicit(w, sizeof(w));
419 
420 	return rc;
421 }
422 
423 /* SP800-56A section 5.6.2.3.3 full verification */
kmb_ocs_ecc_is_pubkey_valid_full(struct ocs_ecc_dev * ecc_dev,const struct ecc_curve * curve,struct ecc_point * pk)424 static int kmb_ocs_ecc_is_pubkey_valid_full(struct ocs_ecc_dev *ecc_dev,
425 					    const struct ecc_curve *curve,
426 					    struct ecc_point *pk)
427 {
428 	struct ecc_point *nQ;
429 	int rc;
430 
431 	/* Checks 1 through 3 */
432 	rc = kmb_ocs_ecc_is_pubkey_valid_partial(ecc_dev, curve, pk);
433 	if (rc)
434 		return rc;
435 
436 	/* Check 4: Verify that nQ is the zero point. */
437 	nQ = ecc_alloc_point(pk->ndigits);
438 	if (!nQ)
439 		return -ENOMEM;
440 
441 	rc = kmb_ecc_point_mult(ecc_dev, nQ, pk, curve->n, curve);
442 	if (rc)
443 		goto exit;
444 
445 	if (!ecc_point_is_zero(nQ))
446 		rc = -EINVAL;
447 
448 exit:
449 	ecc_free_point(nQ);
450 
451 	return rc;
452 }
453 
kmb_ecc_is_key_valid(const struct ecc_curve * curve,const u64 * private_key,size_t private_key_len)454 static int kmb_ecc_is_key_valid(const struct ecc_curve *curve,
455 				const u64 *private_key, size_t private_key_len)
456 {
457 	size_t ndigits = curve->g.ndigits;
458 	u64 one[KMB_ECC_VLI_MAX_DIGITS] = {1};
459 	u64 res[KMB_ECC_VLI_MAX_DIGITS];
460 
461 	if (private_key_len != digits_to_bytes(ndigits))
462 		return -EINVAL;
463 
464 	if (!private_key)
465 		return -EINVAL;
466 
467 	/* Make sure the private key is in the range [2, n-3]. */
468 	if (vli_cmp(one, private_key, ndigits) != -1)
469 		return -EINVAL;
470 
471 	vli_sub(res, curve->n, one, ndigits);
472 	vli_sub(res, res, one, ndigits);
473 	if (vli_cmp(res, private_key, ndigits) != 1)
474 		return -EINVAL;
475 
476 	return 0;
477 }
478 
479 /*
480  * ECC private keys are generated using the method of extra random bits,
481  * equivalent to that described in FIPS 186-4, Appendix B.4.1.
482  *
483  * d = (c mod(n–1)) + 1    where c is a string of random bits, 64 bits longer
484  *                         than requested
485  * 0 <= c mod(n-1) <= n-2  and implies that
486  * 1 <= d <= n-1
487  *
488  * This method generates a private key uniformly distributed in the range
489  * [1, n-1].
490  */
kmb_ecc_gen_privkey(const struct ecc_curve * curve,u64 * privkey)491 static int kmb_ecc_gen_privkey(const struct ecc_curve *curve, u64 *privkey)
492 {
493 	size_t nbytes = digits_to_bytes(curve->g.ndigits);
494 	u64 priv[KMB_ECC_VLI_MAX_DIGITS];
495 	size_t nbits;
496 	int rc;
497 
498 	nbits = vli_num_bits(curve->n, curve->g.ndigits);
499 
500 	/* Check that N is included in Table 1 of FIPS 186-4, section 6.1.1 */
501 	if (nbits < 160 || curve->g.ndigits > ARRAY_SIZE(priv))
502 		return -EINVAL;
503 
504 	/*
505 	 * FIPS 186-4 recommends that the private key should be obtained from a
506 	 * RBG with a security strength equal to or greater than the security
507 	 * strength associated with N.
508 	 *
509 	 * The maximum security strength identified by NIST SP800-57pt1r4 for
510 	 * ECC is 256 (N >= 512).
511 	 *
512 	 * This condition is met by the default RNG because it selects a favored
513 	 * DRBG with a security strength of 256.
514 	 */
515 	if (crypto_get_default_rng())
516 		return -EFAULT;
517 
518 	rc = crypto_rng_get_bytes(crypto_default_rng, (u8 *)priv, nbytes);
519 	crypto_put_default_rng();
520 	if (rc)
521 		goto cleanup;
522 
523 	rc = kmb_ecc_is_key_valid(curve, priv, nbytes);
524 	if (rc)
525 		goto cleanup;
526 
527 	ecc_swap_digits(priv, privkey, curve->g.ndigits);
528 
529 cleanup:
530 	memzero_explicit(&priv, sizeof(priv));
531 
532 	return rc;
533 }
534 
kmb_ocs_ecdh_set_secret(struct crypto_kpp * tfm,const void * buf,unsigned int len)535 static int kmb_ocs_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
536 				   unsigned int len)
537 {
538 	struct ocs_ecc_ctx *tctx = kpp_tfm_ctx(tfm);
539 	struct ecdh params;
540 	int rc = 0;
541 
542 	rc = crypto_ecdh_decode_key(buf, len, &params);
543 	if (rc)
544 		goto cleanup;
545 
546 	/* Ensure key size is not bigger then expected. */
547 	if (params.key_size > digits_to_bytes(tctx->curve->g.ndigits)) {
548 		rc = -EINVAL;
549 		goto cleanup;
550 	}
551 
552 	/* Auto-generate private key is not provided. */
553 	if (!params.key || !params.key_size) {
554 		rc = kmb_ecc_gen_privkey(tctx->curve, tctx->private_key);
555 		goto cleanup;
556 	}
557 
558 	rc = kmb_ecc_is_key_valid(tctx->curve, (const u64 *)params.key,
559 				  params.key_size);
560 	if (rc)
561 		goto cleanup;
562 
563 	ecc_swap_digits((const u64 *)params.key, tctx->private_key,
564 			tctx->curve->g.ndigits);
565 cleanup:
566 	memzero_explicit(&params, sizeof(params));
567 
568 	if (rc)
569 		tctx->curve = NULL;
570 
571 	return rc;
572 }
573 
574 /* Compute shared secret. */
kmb_ecc_do_shared_secret(struct ocs_ecc_ctx * tctx,struct kpp_request * req)575 static int kmb_ecc_do_shared_secret(struct ocs_ecc_ctx *tctx,
576 				    struct kpp_request *req)
577 {
578 	struct ocs_ecc_dev *ecc_dev = tctx->ecc_dev;
579 	const struct ecc_curve *curve = tctx->curve;
580 	u64 shared_secret[KMB_ECC_VLI_MAX_DIGITS];
581 	u64 pubk_buf[KMB_ECC_VLI_MAX_DIGITS * 2];
582 	size_t copied, nbytes, pubk_len;
583 	struct ecc_point *pk, *result;
584 	int rc;
585 
586 	nbytes = digits_to_bytes(curve->g.ndigits);
587 
588 	/* Public key is a point, thus it has two coordinates */
589 	pubk_len = 2 * nbytes;
590 
591 	/* Copy public key from SG list to pubk_buf. */
592 	copied = sg_copy_to_buffer(req->src,
593 				   sg_nents_for_len(req->src, pubk_len),
594 				   pubk_buf, pubk_len);
595 	if (copied != pubk_len)
596 		return -EINVAL;
597 
598 	/* Allocate and initialize public key point. */
599 	pk = ecc_alloc_point(curve->g.ndigits);
600 	if (!pk)
601 		return -ENOMEM;
602 
603 	ecc_swap_digits(pubk_buf, pk->x, curve->g.ndigits);
604 	ecc_swap_digits(&pubk_buf[curve->g.ndigits], pk->y, curve->g.ndigits);
605 
606 	/*
607 	 * Check the public key for following
608 	 * Check 1: Verify key is not the zero point.
609 	 * Check 2: Verify key is in the range [1, p-1].
610 	 * Check 3: Verify that y^2 == (x^3 + a·x + b) mod p
611 	 */
612 	rc = kmb_ocs_ecc_is_pubkey_valid_partial(ecc_dev, curve, pk);
613 	if (rc)
614 		goto exit_free_pk;
615 
616 	/* Allocate point for storing computed shared secret. */
617 	result = ecc_alloc_point(pk->ndigits);
618 	if (!result) {
619 		rc = -ENOMEM;
620 		goto exit_free_pk;
621 	}
622 
623 	/* Calculate the shared secret.*/
624 	rc = kmb_ecc_point_mult(ecc_dev, result, pk, tctx->private_key, curve);
625 	if (rc)
626 		goto exit_free_result;
627 
628 	if (ecc_point_is_zero(result)) {
629 		rc = -EFAULT;
630 		goto exit_free_result;
631 	}
632 
633 	/* Copy shared secret from point to buffer. */
634 	ecc_swap_digits(result->x, shared_secret, result->ndigits);
635 
636 	/* Request might ask for less bytes than what we have. */
637 	nbytes = min_t(size_t, nbytes, req->dst_len);
638 
639 	copied = sg_copy_from_buffer(req->dst,
640 				     sg_nents_for_len(req->dst, nbytes),
641 				     shared_secret, nbytes);
642 
643 	if (copied != nbytes)
644 		rc = -EINVAL;
645 
646 	memzero_explicit(shared_secret, sizeof(shared_secret));
647 
648 exit_free_result:
649 	ecc_free_point(result);
650 
651 exit_free_pk:
652 	ecc_free_point(pk);
653 
654 	return rc;
655 }
656 
657 /* Compute public key. */
kmb_ecc_do_public_key(struct ocs_ecc_ctx * tctx,struct kpp_request * req)658 static int kmb_ecc_do_public_key(struct ocs_ecc_ctx *tctx,
659 				 struct kpp_request *req)
660 {
661 	const struct ecc_curve *curve = tctx->curve;
662 	u64 pubk_buf[KMB_ECC_VLI_MAX_DIGITS * 2];
663 	struct ecc_point *pk;
664 	size_t pubk_len;
665 	size_t copied;
666 	int rc;
667 
668 	/* Public key is a point, so it has double the digits. */
669 	pubk_len = 2 * digits_to_bytes(curve->g.ndigits);
670 
671 	pk = ecc_alloc_point(curve->g.ndigits);
672 	if (!pk)
673 		return -ENOMEM;
674 
675 	/* Public Key(pk) = priv * G. */
676 	rc = kmb_ecc_point_mult(tctx->ecc_dev, pk, &curve->g, tctx->private_key,
677 				curve);
678 	if (rc)
679 		goto exit;
680 
681 	/* SP800-56A rev 3 5.6.2.1.3 key check */
682 	if (kmb_ocs_ecc_is_pubkey_valid_full(tctx->ecc_dev, curve, pk)) {
683 		rc = -EAGAIN;
684 		goto exit;
685 	}
686 
687 	/* Copy public key from point to buffer. */
688 	ecc_swap_digits(pk->x, pubk_buf, pk->ndigits);
689 	ecc_swap_digits(pk->y, &pubk_buf[pk->ndigits], pk->ndigits);
690 
691 	/* Copy public key to req->dst. */
692 	copied = sg_copy_from_buffer(req->dst,
693 				     sg_nents_for_len(req->dst, pubk_len),
694 				     pubk_buf, pubk_len);
695 
696 	if (copied != pubk_len)
697 		rc = -EINVAL;
698 
699 exit:
700 	ecc_free_point(pk);
701 
702 	return rc;
703 }
704 
kmb_ocs_ecc_do_one_request(struct crypto_engine * engine,void * areq)705 static int kmb_ocs_ecc_do_one_request(struct crypto_engine *engine,
706 				      void *areq)
707 {
708 	struct kpp_request *req = container_of(areq, struct kpp_request, base);
709 	struct ocs_ecc_ctx *tctx = kmb_ocs_ecc_tctx(req);
710 	struct ocs_ecc_dev *ecc_dev = tctx->ecc_dev;
711 	int rc;
712 
713 	if (req->src)
714 		rc = kmb_ecc_do_shared_secret(tctx, req);
715 	else
716 		rc = kmb_ecc_do_public_key(tctx, req);
717 
718 	crypto_finalize_kpp_request(ecc_dev->engine, req, rc);
719 
720 	return 0;
721 }
722 
kmb_ocs_ecdh_generate_public_key(struct kpp_request * req)723 static int kmb_ocs_ecdh_generate_public_key(struct kpp_request *req)
724 {
725 	struct ocs_ecc_ctx *tctx = kmb_ocs_ecc_tctx(req);
726 	const struct ecc_curve *curve = tctx->curve;
727 
728 	/* Ensure kmb_ocs_ecdh_set_secret() has been successfully called. */
729 	if (!tctx->curve)
730 		return -EINVAL;
731 
732 	/* Ensure dst is present. */
733 	if (!req->dst)
734 		return -EINVAL;
735 
736 	/* Check the request dst is big enough to hold the public key. */
737 	if (req->dst_len < (2 * digits_to_bytes(curve->g.ndigits)))
738 		return -EINVAL;
739 
740 	/* 'src' is not supposed to be present when generate pubk is called. */
741 	if (req->src)
742 		return -EINVAL;
743 
744 	return crypto_transfer_kpp_request_to_engine(tctx->ecc_dev->engine,
745 						     req);
746 }
747 
kmb_ocs_ecdh_compute_shared_secret(struct kpp_request * req)748 static int kmb_ocs_ecdh_compute_shared_secret(struct kpp_request *req)
749 {
750 	struct ocs_ecc_ctx *tctx = kmb_ocs_ecc_tctx(req);
751 	const struct ecc_curve *curve = tctx->curve;
752 
753 	/* Ensure kmb_ocs_ecdh_set_secret() has been successfully called. */
754 	if (!tctx->curve)
755 		return -EINVAL;
756 
757 	/* Ensure dst is present. */
758 	if (!req->dst)
759 		return -EINVAL;
760 
761 	/* Ensure src is present. */
762 	if (!req->src)
763 		return -EINVAL;
764 
765 	/*
766 	 * req->src is expected to the (other-side) public key, so its length
767 	 * must be 2 * coordinate size (in bytes).
768 	 */
769 	if (req->src_len != 2 * digits_to_bytes(curve->g.ndigits))
770 		return -EINVAL;
771 
772 	return crypto_transfer_kpp_request_to_engine(tctx->ecc_dev->engine,
773 						     req);
774 }
775 
kmb_ecc_tctx_init(struct ocs_ecc_ctx * tctx,unsigned int curve_id)776 static int kmb_ecc_tctx_init(struct ocs_ecc_ctx *tctx, unsigned int curve_id)
777 {
778 	memset(tctx, 0, sizeof(*tctx));
779 
780 	tctx->ecc_dev = kmb_ocs_ecc_find_dev(tctx);
781 
782 	if (IS_ERR(tctx->ecc_dev)) {
783 		pr_err("Failed to find the device : %ld\n",
784 		       PTR_ERR(tctx->ecc_dev));
785 		return PTR_ERR(tctx->ecc_dev);
786 	}
787 
788 	tctx->curve = ecc_get_curve(curve_id);
789 	if (!tctx->curve)
790 		return -EOPNOTSUPP;
791 
792 	return 0;
793 }
794 
kmb_ocs_ecdh_nist_p256_init_tfm(struct crypto_kpp * tfm)795 static int kmb_ocs_ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
796 {
797 	struct ocs_ecc_ctx *tctx = kpp_tfm_ctx(tfm);
798 
799 	return kmb_ecc_tctx_init(tctx, ECC_CURVE_NIST_P256);
800 }
801 
kmb_ocs_ecdh_nist_p384_init_tfm(struct crypto_kpp * tfm)802 static int kmb_ocs_ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm)
803 {
804 	struct ocs_ecc_ctx *tctx = kpp_tfm_ctx(tfm);
805 
806 	return kmb_ecc_tctx_init(tctx, ECC_CURVE_NIST_P384);
807 }
808 
kmb_ocs_ecdh_exit_tfm(struct crypto_kpp * tfm)809 static void kmb_ocs_ecdh_exit_tfm(struct crypto_kpp *tfm)
810 {
811 	struct ocs_ecc_ctx *tctx = kpp_tfm_ctx(tfm);
812 
813 	memzero_explicit(tctx->private_key, sizeof(*tctx->private_key));
814 }
815 
kmb_ocs_ecdh_max_size(struct crypto_kpp * tfm)816 static unsigned int kmb_ocs_ecdh_max_size(struct crypto_kpp *tfm)
817 {
818 	struct ocs_ecc_ctx *tctx = kpp_tfm_ctx(tfm);
819 
820 	/* Public key is made of two coordinates, so double the digits. */
821 	return digits_to_bytes(tctx->curve->g.ndigits) * 2;
822 }
823 
824 static struct kpp_engine_alg ocs_ecdh_p256 = {
825 	.base.set_secret = kmb_ocs_ecdh_set_secret,
826 	.base.generate_public_key = kmb_ocs_ecdh_generate_public_key,
827 	.base.compute_shared_secret = kmb_ocs_ecdh_compute_shared_secret,
828 	.base.init = kmb_ocs_ecdh_nist_p256_init_tfm,
829 	.base.exit = kmb_ocs_ecdh_exit_tfm,
830 	.base.max_size = kmb_ocs_ecdh_max_size,
831 	.base.base = {
832 		.cra_name = "ecdh-nist-p256",
833 		.cra_driver_name = "ecdh-nist-p256-keembay-ocs",
834 		.cra_priority = KMB_OCS_ECC_PRIORITY,
835 		.cra_module = THIS_MODULE,
836 		.cra_ctxsize = sizeof(struct ocs_ecc_ctx),
837 	},
838 	.op.do_one_request = kmb_ocs_ecc_do_one_request,
839 };
840 
841 static struct kpp_engine_alg ocs_ecdh_p384 = {
842 	.base.set_secret = kmb_ocs_ecdh_set_secret,
843 	.base.generate_public_key = kmb_ocs_ecdh_generate_public_key,
844 	.base.compute_shared_secret = kmb_ocs_ecdh_compute_shared_secret,
845 	.base.init = kmb_ocs_ecdh_nist_p384_init_tfm,
846 	.base.exit = kmb_ocs_ecdh_exit_tfm,
847 	.base.max_size = kmb_ocs_ecdh_max_size,
848 	.base.base = {
849 		.cra_name = "ecdh-nist-p384",
850 		.cra_driver_name = "ecdh-nist-p384-keembay-ocs",
851 		.cra_priority = KMB_OCS_ECC_PRIORITY,
852 		.cra_module = THIS_MODULE,
853 		.cra_ctxsize = sizeof(struct ocs_ecc_ctx),
854 	},
855 	.op.do_one_request = kmb_ocs_ecc_do_one_request,
856 };
857 
ocs_ecc_irq_handler(int irq,void * dev_id)858 static irqreturn_t ocs_ecc_irq_handler(int irq, void *dev_id)
859 {
860 	struct ocs_ecc_dev *ecc_dev = dev_id;
861 	u32 status;
862 
863 	/*
864 	 * Read the status register and write it back to clear the
865 	 * DONE_INT_STATUS bit.
866 	 */
867 	status = ioread32(ecc_dev->base_reg + HW_OFFS_OCS_ECC_ISR);
868 	iowrite32(status, ecc_dev->base_reg + HW_OFFS_OCS_ECC_ISR);
869 
870 	if (!(status & HW_OCS_ECC_ISR_INT_STATUS_DONE))
871 		return IRQ_NONE;
872 
873 	complete(&ecc_dev->irq_done);
874 
875 	return IRQ_HANDLED;
876 }
877 
kmb_ocs_ecc_probe(struct platform_device * pdev)878 static int kmb_ocs_ecc_probe(struct platform_device *pdev)
879 {
880 	struct device *dev = &pdev->dev;
881 	struct ocs_ecc_dev *ecc_dev;
882 	int rc;
883 
884 	ecc_dev = devm_kzalloc(dev, sizeof(*ecc_dev), GFP_KERNEL);
885 	if (!ecc_dev)
886 		return -ENOMEM;
887 
888 	ecc_dev->dev = dev;
889 
890 	platform_set_drvdata(pdev, ecc_dev);
891 
892 	INIT_LIST_HEAD(&ecc_dev->list);
893 	init_completion(&ecc_dev->irq_done);
894 
895 	/* Get base register address. */
896 	ecc_dev->base_reg = devm_platform_ioremap_resource(pdev, 0);
897 	if (IS_ERR(ecc_dev->base_reg)) {
898 		dev_err(dev, "Failed to get base address\n");
899 		rc = PTR_ERR(ecc_dev->base_reg);
900 		goto list_del;
901 	}
902 
903 	/* Get and request IRQ */
904 	ecc_dev->irq = platform_get_irq(pdev, 0);
905 	if (ecc_dev->irq < 0) {
906 		rc = ecc_dev->irq;
907 		goto list_del;
908 	}
909 
910 	rc = devm_request_threaded_irq(dev, ecc_dev->irq, ocs_ecc_irq_handler,
911 				       NULL, 0, "keembay-ocs-ecc", ecc_dev);
912 	if (rc < 0) {
913 		dev_err(dev, "Could not request IRQ\n");
914 		goto list_del;
915 	}
916 
917 	/* Add device to the list of OCS ECC devices. */
918 	spin_lock(&ocs_ecc.lock);
919 	list_add_tail(&ecc_dev->list, &ocs_ecc.dev_list);
920 	spin_unlock(&ocs_ecc.lock);
921 
922 	/* Initialize crypto engine. */
923 	ecc_dev->engine = crypto_engine_alloc_init(dev, 1);
924 	if (!ecc_dev->engine) {
925 		dev_err(dev, "Could not allocate crypto engine\n");
926 		rc = -ENOMEM;
927 		goto list_del;
928 	}
929 
930 	rc = crypto_engine_start(ecc_dev->engine);
931 	if (rc) {
932 		dev_err(dev, "Could not start crypto engine\n");
933 		goto cleanup;
934 	}
935 
936 	/* Register the KPP algo. */
937 	rc = crypto_engine_register_kpp(&ocs_ecdh_p256);
938 	if (rc) {
939 		dev_err(dev,
940 			"Could not register OCS algorithms with Crypto API\n");
941 		goto cleanup;
942 	}
943 
944 	rc = crypto_engine_register_kpp(&ocs_ecdh_p384);
945 	if (rc) {
946 		dev_err(dev,
947 			"Could not register OCS algorithms with Crypto API\n");
948 		goto ocs_ecdh_p384_error;
949 	}
950 
951 	return 0;
952 
953 ocs_ecdh_p384_error:
954 	crypto_engine_unregister_kpp(&ocs_ecdh_p256);
955 
956 cleanup:
957 	crypto_engine_exit(ecc_dev->engine);
958 
959 list_del:
960 	spin_lock(&ocs_ecc.lock);
961 	list_del(&ecc_dev->list);
962 	spin_unlock(&ocs_ecc.lock);
963 
964 	return rc;
965 }
966 
kmb_ocs_ecc_remove(struct platform_device * pdev)967 static int kmb_ocs_ecc_remove(struct platform_device *pdev)
968 {
969 	struct ocs_ecc_dev *ecc_dev;
970 
971 	ecc_dev = platform_get_drvdata(pdev);
972 
973 	crypto_engine_unregister_kpp(&ocs_ecdh_p384);
974 	crypto_engine_unregister_kpp(&ocs_ecdh_p256);
975 
976 	spin_lock(&ocs_ecc.lock);
977 	list_del(&ecc_dev->list);
978 	spin_unlock(&ocs_ecc.lock);
979 
980 	crypto_engine_exit(ecc_dev->engine);
981 
982 	return 0;
983 }
984 
985 /* Device tree driver match. */
986 static const struct of_device_id kmb_ocs_ecc_of_match[] = {
987 	{
988 		.compatible = "intel,keembay-ocs-ecc",
989 	},
990 	{}
991 };
992 
993 /* The OCS driver is a platform device. */
994 static struct platform_driver kmb_ocs_ecc_driver = {
995 	.probe = kmb_ocs_ecc_probe,
996 	.remove = kmb_ocs_ecc_remove,
997 	.driver = {
998 			.name = DRV_NAME,
999 			.of_match_table = kmb_ocs_ecc_of_match,
1000 		},
1001 };
1002 module_platform_driver(kmb_ocs_ecc_driver);
1003 
1004 MODULE_LICENSE("GPL");
1005 MODULE_DESCRIPTION("Intel Keem Bay OCS ECC Driver");
1006 MODULE_ALIAS_CRYPTO("ecdh-nist-p256");
1007 MODULE_ALIAS_CRYPTO("ecdh-nist-p384");
1008 MODULE_ALIAS_CRYPTO("ecdh-nist-p256-keembay-ocs");
1009 MODULE_ALIAS_CRYPTO("ecdh-nist-p384-keembay-ocs");
1010