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1 /*
2  * ChaCha20-Poly1305 AEAD, RFC7539
3  *
4  * Copyright (C) 2015 Martin Willi
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  */
11 
12 #include <crypto/internal/aead.h>
13 #include <crypto/internal/hash.h>
14 #include <crypto/internal/skcipher.h>
15 #include <crypto/scatterwalk.h>
16 #include <crypto/chacha20.h>
17 #include <crypto/poly1305.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 
23 #include "internal.h"
24 
25 #define CHACHAPOLY_IV_SIZE	12
26 
27 struct chachapoly_instance_ctx {
28 	struct crypto_skcipher_spawn chacha;
29 	struct crypto_ahash_spawn poly;
30 	unsigned int saltlen;
31 };
32 
33 struct chachapoly_ctx {
34 	struct crypto_skcipher *chacha;
35 	struct crypto_ahash *poly;
36 	/* key bytes we use for the ChaCha20 IV */
37 	unsigned int saltlen;
38 	u8 salt[];
39 };
40 
41 struct poly_req {
42 	/* zero byte padding for AD/ciphertext, as needed */
43 	u8 pad[POLY1305_BLOCK_SIZE];
44 	/* tail data with AD/ciphertext lengths */
45 	struct {
46 		__le64 assoclen;
47 		__le64 cryptlen;
48 	} tail;
49 	struct scatterlist src[1];
50 	struct ahash_request req; /* must be last member */
51 };
52 
53 struct chacha_req {
54 	u8 iv[CHACHA20_IV_SIZE];
55 	struct scatterlist src[1];
56 	struct skcipher_request req; /* must be last member */
57 };
58 
59 struct chachapoly_req_ctx {
60 	struct scatterlist src[2];
61 	struct scatterlist dst[2];
62 	/* the key we generate for Poly1305 using Chacha20 */
63 	u8 key[POLY1305_KEY_SIZE];
64 	/* calculated Poly1305 tag */
65 	u8 tag[POLY1305_DIGEST_SIZE];
66 	/* length of data to en/decrypt, without ICV */
67 	unsigned int cryptlen;
68 	/* Actual AD, excluding IV */
69 	unsigned int assoclen;
70 	/* request flags, with MAY_SLEEP cleared if needed */
71 	u32 flags;
72 	union {
73 		struct poly_req poly;
74 		struct chacha_req chacha;
75 	} u;
76 };
77 
async_done_continue(struct aead_request * req,int err,int (* cont)(struct aead_request *))78 static inline void async_done_continue(struct aead_request *req, int err,
79 				       int (*cont)(struct aead_request *))
80 {
81 	if (!err) {
82 		struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
83 
84 		rctx->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
85 		err = cont(req);
86 	}
87 
88 	if (err != -EINPROGRESS && err != -EBUSY)
89 		aead_request_complete(req, err);
90 }
91 
chacha_iv(u8 * iv,struct aead_request * req,u32 icb)92 static void chacha_iv(u8 *iv, struct aead_request *req, u32 icb)
93 {
94 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
95 	__le32 leicb = cpu_to_le32(icb);
96 
97 	memcpy(iv, &leicb, sizeof(leicb));
98 	memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen);
99 	memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv,
100 	       CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen);
101 }
102 
poly_verify_tag(struct aead_request * req)103 static int poly_verify_tag(struct aead_request *req)
104 {
105 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
106 	u8 tag[sizeof(rctx->tag)];
107 
108 	scatterwalk_map_and_copy(tag, req->src,
109 				 req->assoclen + rctx->cryptlen,
110 				 sizeof(tag), 0);
111 	if (crypto_memneq(tag, rctx->tag, sizeof(tag)))
112 		return -EBADMSG;
113 	return 0;
114 }
115 
poly_copy_tag(struct aead_request * req)116 static int poly_copy_tag(struct aead_request *req)
117 {
118 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
119 
120 	scatterwalk_map_and_copy(rctx->tag, req->dst,
121 				 req->assoclen + rctx->cryptlen,
122 				 sizeof(rctx->tag), 1);
123 	return 0;
124 }
125 
chacha_decrypt_done(struct crypto_async_request * areq,int err)126 static void chacha_decrypt_done(struct crypto_async_request *areq, int err)
127 {
128 	async_done_continue(areq->data, err, poly_verify_tag);
129 }
130 
chacha_decrypt(struct aead_request * req)131 static int chacha_decrypt(struct aead_request *req)
132 {
133 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
134 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
135 	struct chacha_req *creq = &rctx->u.chacha;
136 	struct scatterlist *src, *dst;
137 	int err;
138 
139 	if (rctx->cryptlen == 0)
140 		goto skip;
141 
142 	chacha_iv(creq->iv, req, 1);
143 
144 	sg_init_table(rctx->src, 2);
145 	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
146 	dst = src;
147 
148 	if (req->src != req->dst) {
149 		sg_init_table(rctx->dst, 2);
150 		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
151 	}
152 
153 	skcipher_request_set_callback(&creq->req, rctx->flags,
154 				      chacha_decrypt_done, req);
155 	skcipher_request_set_tfm(&creq->req, ctx->chacha);
156 	skcipher_request_set_crypt(&creq->req, src, dst,
157 				   rctx->cryptlen, creq->iv);
158 	err = crypto_skcipher_decrypt(&creq->req);
159 	if (err)
160 		return err;
161 
162 skip:
163 	return poly_verify_tag(req);
164 }
165 
poly_tail_continue(struct aead_request * req)166 static int poly_tail_continue(struct aead_request *req)
167 {
168 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
169 
170 	if (rctx->cryptlen == req->cryptlen) /* encrypting */
171 		return poly_copy_tag(req);
172 
173 	return chacha_decrypt(req);
174 }
175 
poly_tail_done(struct crypto_async_request * areq,int err)176 static void poly_tail_done(struct crypto_async_request *areq, int err)
177 {
178 	async_done_continue(areq->data, err, poly_tail_continue);
179 }
180 
poly_tail(struct aead_request * req)181 static int poly_tail(struct aead_request *req)
182 {
183 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
184 	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
185 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
186 	struct poly_req *preq = &rctx->u.poly;
187 	__le64 len;
188 	int err;
189 
190 	sg_init_table(preq->src, 1);
191 	len = cpu_to_le64(rctx->assoclen);
192 	memcpy(&preq->tail.assoclen, &len, sizeof(len));
193 	len = cpu_to_le64(rctx->cryptlen);
194 	memcpy(&preq->tail.cryptlen, &len, sizeof(len));
195 	sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));
196 
197 	ahash_request_set_callback(&preq->req, rctx->flags,
198 				   poly_tail_done, req);
199 	ahash_request_set_tfm(&preq->req, ctx->poly);
200 	ahash_request_set_crypt(&preq->req, preq->src,
201 				rctx->tag, sizeof(preq->tail));
202 
203 	err = crypto_ahash_finup(&preq->req);
204 	if (err)
205 		return err;
206 
207 	return poly_tail_continue(req);
208 }
209 
poly_cipherpad_done(struct crypto_async_request * areq,int err)210 static void poly_cipherpad_done(struct crypto_async_request *areq, int err)
211 {
212 	async_done_continue(areq->data, err, poly_tail);
213 }
214 
poly_cipherpad(struct aead_request * req)215 static int poly_cipherpad(struct aead_request *req)
216 {
217 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
218 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
219 	struct poly_req *preq = &rctx->u.poly;
220 	unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
221 	int err;
222 
223 	padlen = (bs - (rctx->cryptlen % bs)) % bs;
224 	memset(preq->pad, 0, sizeof(preq->pad));
225 	sg_init_table(preq->src, 1);
226 	sg_set_buf(preq->src, &preq->pad, padlen);
227 
228 	ahash_request_set_callback(&preq->req, rctx->flags,
229 				   poly_cipherpad_done, req);
230 	ahash_request_set_tfm(&preq->req, ctx->poly);
231 	ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
232 
233 	err = crypto_ahash_update(&preq->req);
234 	if (err)
235 		return err;
236 
237 	return poly_tail(req);
238 }
239 
poly_cipher_done(struct crypto_async_request * areq,int err)240 static void poly_cipher_done(struct crypto_async_request *areq, int err)
241 {
242 	async_done_continue(areq->data, err, poly_cipherpad);
243 }
244 
poly_cipher(struct aead_request * req)245 static int poly_cipher(struct aead_request *req)
246 {
247 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
248 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
249 	struct poly_req *preq = &rctx->u.poly;
250 	struct scatterlist *crypt = req->src;
251 	int err;
252 
253 	if (rctx->cryptlen == req->cryptlen) /* encrypting */
254 		crypt = req->dst;
255 
256 	sg_init_table(rctx->src, 2);
257 	crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen);
258 
259 	ahash_request_set_callback(&preq->req, rctx->flags,
260 				   poly_cipher_done, req);
261 	ahash_request_set_tfm(&preq->req, ctx->poly);
262 	ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
263 
264 	err = crypto_ahash_update(&preq->req);
265 	if (err)
266 		return err;
267 
268 	return poly_cipherpad(req);
269 }
270 
poly_adpad_done(struct crypto_async_request * areq,int err)271 static void poly_adpad_done(struct crypto_async_request *areq, int err)
272 {
273 	async_done_continue(areq->data, err, poly_cipher);
274 }
275 
poly_adpad(struct aead_request * req)276 static int poly_adpad(struct aead_request *req)
277 {
278 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
279 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
280 	struct poly_req *preq = &rctx->u.poly;
281 	unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
282 	int err;
283 
284 	padlen = (bs - (rctx->assoclen % bs)) % bs;
285 	memset(preq->pad, 0, sizeof(preq->pad));
286 	sg_init_table(preq->src, 1);
287 	sg_set_buf(preq->src, preq->pad, padlen);
288 
289 	ahash_request_set_callback(&preq->req, rctx->flags,
290 				   poly_adpad_done, req);
291 	ahash_request_set_tfm(&preq->req, ctx->poly);
292 	ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
293 
294 	err = crypto_ahash_update(&preq->req);
295 	if (err)
296 		return err;
297 
298 	return poly_cipher(req);
299 }
300 
poly_ad_done(struct crypto_async_request * areq,int err)301 static void poly_ad_done(struct crypto_async_request *areq, int err)
302 {
303 	async_done_continue(areq->data, err, poly_adpad);
304 }
305 
poly_ad(struct aead_request * req)306 static int poly_ad(struct aead_request *req)
307 {
308 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
309 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
310 	struct poly_req *preq = &rctx->u.poly;
311 	int err;
312 
313 	ahash_request_set_callback(&preq->req, rctx->flags,
314 				   poly_ad_done, req);
315 	ahash_request_set_tfm(&preq->req, ctx->poly);
316 	ahash_request_set_crypt(&preq->req, req->src, NULL, rctx->assoclen);
317 
318 	err = crypto_ahash_update(&preq->req);
319 	if (err)
320 		return err;
321 
322 	return poly_adpad(req);
323 }
324 
poly_setkey_done(struct crypto_async_request * areq,int err)325 static void poly_setkey_done(struct crypto_async_request *areq, int err)
326 {
327 	async_done_continue(areq->data, err, poly_ad);
328 }
329 
poly_setkey(struct aead_request * req)330 static int poly_setkey(struct aead_request *req)
331 {
332 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
333 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
334 	struct poly_req *preq = &rctx->u.poly;
335 	int err;
336 
337 	sg_init_table(preq->src, 1);
338 	sg_set_buf(preq->src, rctx->key, sizeof(rctx->key));
339 
340 	ahash_request_set_callback(&preq->req, rctx->flags,
341 				   poly_setkey_done, req);
342 	ahash_request_set_tfm(&preq->req, ctx->poly);
343 	ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key));
344 
345 	err = crypto_ahash_update(&preq->req);
346 	if (err)
347 		return err;
348 
349 	return poly_ad(req);
350 }
351 
poly_init_done(struct crypto_async_request * areq,int err)352 static void poly_init_done(struct crypto_async_request *areq, int err)
353 {
354 	async_done_continue(areq->data, err, poly_setkey);
355 }
356 
poly_init(struct aead_request * req)357 static int poly_init(struct aead_request *req)
358 {
359 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
360 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
361 	struct poly_req *preq = &rctx->u.poly;
362 	int err;
363 
364 	ahash_request_set_callback(&preq->req, rctx->flags,
365 				   poly_init_done, req);
366 	ahash_request_set_tfm(&preq->req, ctx->poly);
367 
368 	err = crypto_ahash_init(&preq->req);
369 	if (err)
370 		return err;
371 
372 	return poly_setkey(req);
373 }
374 
poly_genkey_done(struct crypto_async_request * areq,int err)375 static void poly_genkey_done(struct crypto_async_request *areq, int err)
376 {
377 	async_done_continue(areq->data, err, poly_init);
378 }
379 
poly_genkey(struct aead_request * req)380 static int poly_genkey(struct aead_request *req)
381 {
382 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
383 	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
384 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
385 	struct chacha_req *creq = &rctx->u.chacha;
386 	int err;
387 
388 	rctx->assoclen = req->assoclen;
389 
390 	if (crypto_aead_ivsize(tfm) == 8) {
391 		if (rctx->assoclen < 8)
392 			return -EINVAL;
393 		rctx->assoclen -= 8;
394 	}
395 
396 	sg_init_table(creq->src, 1);
397 	memset(rctx->key, 0, sizeof(rctx->key));
398 	sg_set_buf(creq->src, rctx->key, sizeof(rctx->key));
399 
400 	chacha_iv(creq->iv, req, 0);
401 
402 	skcipher_request_set_callback(&creq->req, rctx->flags,
403 				      poly_genkey_done, req);
404 	skcipher_request_set_tfm(&creq->req, ctx->chacha);
405 	skcipher_request_set_crypt(&creq->req, creq->src, creq->src,
406 				   POLY1305_KEY_SIZE, creq->iv);
407 
408 	err = crypto_skcipher_decrypt(&creq->req);
409 	if (err)
410 		return err;
411 
412 	return poly_init(req);
413 }
414 
chacha_encrypt_done(struct crypto_async_request * areq,int err)415 static void chacha_encrypt_done(struct crypto_async_request *areq, int err)
416 {
417 	async_done_continue(areq->data, err, poly_genkey);
418 }
419 
chacha_encrypt(struct aead_request * req)420 static int chacha_encrypt(struct aead_request *req)
421 {
422 	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
423 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
424 	struct chacha_req *creq = &rctx->u.chacha;
425 	struct scatterlist *src, *dst;
426 	int err;
427 
428 	if (req->cryptlen == 0)
429 		goto skip;
430 
431 	chacha_iv(creq->iv, req, 1);
432 
433 	sg_init_table(rctx->src, 2);
434 	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
435 	dst = src;
436 
437 	if (req->src != req->dst) {
438 		sg_init_table(rctx->dst, 2);
439 		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
440 	}
441 
442 	skcipher_request_set_callback(&creq->req, rctx->flags,
443 				      chacha_encrypt_done, req);
444 	skcipher_request_set_tfm(&creq->req, ctx->chacha);
445 	skcipher_request_set_crypt(&creq->req, src, dst,
446 				   req->cryptlen, creq->iv);
447 	err = crypto_skcipher_encrypt(&creq->req);
448 	if (err)
449 		return err;
450 
451 skip:
452 	return poly_genkey(req);
453 }
454 
chachapoly_encrypt(struct aead_request * req)455 static int chachapoly_encrypt(struct aead_request *req)
456 {
457 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
458 
459 	rctx->cryptlen = req->cryptlen;
460 	rctx->flags = aead_request_flags(req);
461 
462 	/* encrypt call chain:
463 	 * - chacha_encrypt/done()
464 	 * - poly_genkey/done()
465 	 * - poly_init/done()
466 	 * - poly_setkey/done()
467 	 * - poly_ad/done()
468 	 * - poly_adpad/done()
469 	 * - poly_cipher/done()
470 	 * - poly_cipherpad/done()
471 	 * - poly_tail/done/continue()
472 	 * - poly_copy_tag()
473 	 */
474 	return chacha_encrypt(req);
475 }
476 
chachapoly_decrypt(struct aead_request * req)477 static int chachapoly_decrypt(struct aead_request *req)
478 {
479 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
480 
481 	rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
482 	rctx->flags = aead_request_flags(req);
483 
484 	/* decrypt call chain:
485 	 * - poly_genkey/done()
486 	 * - poly_init/done()
487 	 * - poly_setkey/done()
488 	 * - poly_ad/done()
489 	 * - poly_adpad/done()
490 	 * - poly_cipher/done()
491 	 * - poly_cipherpad/done()
492 	 * - poly_tail/done/continue()
493 	 * - chacha_decrypt/done()
494 	 * - poly_verify_tag()
495 	 */
496 	return poly_genkey(req);
497 }
498 
chachapoly_setkey(struct crypto_aead * aead,const u8 * key,unsigned int keylen)499 static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key,
500 			     unsigned int keylen)
501 {
502 	struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
503 	int err;
504 
505 	if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
506 		return -EINVAL;
507 
508 	keylen -= ctx->saltlen;
509 	memcpy(ctx->salt, key + keylen, ctx->saltlen);
510 
511 	crypto_skcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK);
512 	crypto_skcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) &
513 					       CRYPTO_TFM_REQ_MASK);
514 
515 	err = crypto_skcipher_setkey(ctx->chacha, key, keylen);
516 	crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctx->chacha) &
517 				    CRYPTO_TFM_RES_MASK);
518 	return err;
519 }
520 
chachapoly_setauthsize(struct crypto_aead * tfm,unsigned int authsize)521 static int chachapoly_setauthsize(struct crypto_aead *tfm,
522 				  unsigned int authsize)
523 {
524 	if (authsize != POLY1305_DIGEST_SIZE)
525 		return -EINVAL;
526 
527 	return 0;
528 }
529 
chachapoly_init(struct crypto_aead * tfm)530 static int chachapoly_init(struct crypto_aead *tfm)
531 {
532 	struct aead_instance *inst = aead_alg_instance(tfm);
533 	struct chachapoly_instance_ctx *ictx = aead_instance_ctx(inst);
534 	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
535 	struct crypto_skcipher *chacha;
536 	struct crypto_ahash *poly;
537 	unsigned long align;
538 
539 	poly = crypto_spawn_ahash(&ictx->poly);
540 	if (IS_ERR(poly))
541 		return PTR_ERR(poly);
542 
543 	chacha = crypto_spawn_skcipher(&ictx->chacha);
544 	if (IS_ERR(chacha)) {
545 		crypto_free_ahash(poly);
546 		return PTR_ERR(chacha);
547 	}
548 
549 	ctx->chacha = chacha;
550 	ctx->poly = poly;
551 	ctx->saltlen = ictx->saltlen;
552 
553 	align = crypto_aead_alignmask(tfm);
554 	align &= ~(crypto_tfm_ctx_alignment() - 1);
555 	crypto_aead_set_reqsize(
556 		tfm,
557 		align + offsetof(struct chachapoly_req_ctx, u) +
558 		max(offsetof(struct chacha_req, req) +
559 		    sizeof(struct skcipher_request) +
560 		    crypto_skcipher_reqsize(chacha),
561 		    offsetof(struct poly_req, req) +
562 		    sizeof(struct ahash_request) +
563 		    crypto_ahash_reqsize(poly)));
564 
565 	return 0;
566 }
567 
chachapoly_exit(struct crypto_aead * tfm)568 static void chachapoly_exit(struct crypto_aead *tfm)
569 {
570 	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);
571 
572 	crypto_free_ahash(ctx->poly);
573 	crypto_free_skcipher(ctx->chacha);
574 }
575 
chachapoly_free(struct aead_instance * inst)576 static void chachapoly_free(struct aead_instance *inst)
577 {
578 	struct chachapoly_instance_ctx *ctx = aead_instance_ctx(inst);
579 
580 	crypto_drop_skcipher(&ctx->chacha);
581 	crypto_drop_ahash(&ctx->poly);
582 	kfree(inst);
583 }
584 
chachapoly_create(struct crypto_template * tmpl,struct rtattr ** tb,const char * name,unsigned int ivsize)585 static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
586 			     const char *name, unsigned int ivsize)
587 {
588 	struct crypto_attr_type *algt;
589 	struct aead_instance *inst;
590 	struct skcipher_alg *chacha;
591 	struct crypto_alg *poly;
592 	struct hash_alg_common *poly_hash;
593 	struct chachapoly_instance_ctx *ctx;
594 	const char *chacha_name, *poly_name;
595 	int err;
596 
597 	if (ivsize > CHACHAPOLY_IV_SIZE)
598 		return -EINVAL;
599 
600 	algt = crypto_get_attr_type(tb);
601 	if (IS_ERR(algt))
602 		return PTR_ERR(algt);
603 
604 	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
605 		return -EINVAL;
606 
607 	chacha_name = crypto_attr_alg_name(tb[1]);
608 	if (IS_ERR(chacha_name))
609 		return PTR_ERR(chacha_name);
610 	poly_name = crypto_attr_alg_name(tb[2]);
611 	if (IS_ERR(poly_name))
612 		return PTR_ERR(poly_name);
613 
614 	poly = crypto_find_alg(poly_name, &crypto_ahash_type,
615 			       CRYPTO_ALG_TYPE_HASH,
616 			       CRYPTO_ALG_TYPE_AHASH_MASK |
617 			       crypto_requires_sync(algt->type,
618 						    algt->mask));
619 	if (IS_ERR(poly))
620 		return PTR_ERR(poly);
621 	poly_hash = __crypto_hash_alg_common(poly);
622 
623 	err = -EINVAL;
624 	if (poly_hash->digestsize != POLY1305_DIGEST_SIZE)
625 		goto out_put_poly;
626 
627 	err = -ENOMEM;
628 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
629 	if (!inst)
630 		goto out_put_poly;
631 
632 	ctx = aead_instance_ctx(inst);
633 	ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;
634 	err = crypto_init_ahash_spawn(&ctx->poly, poly_hash,
635 				      aead_crypto_instance(inst));
636 	if (err)
637 		goto err_free_inst;
638 
639 	crypto_set_skcipher_spawn(&ctx->chacha, aead_crypto_instance(inst));
640 	err = crypto_grab_skcipher(&ctx->chacha, chacha_name, 0,
641 				   crypto_requires_sync(algt->type,
642 							algt->mask));
643 	if (err)
644 		goto err_drop_poly;
645 
646 	chacha = crypto_spawn_skcipher_alg(&ctx->chacha);
647 
648 	err = -EINVAL;
649 	/* Need 16-byte IV size, including Initial Block Counter value */
650 	if (crypto_skcipher_alg_ivsize(chacha) != CHACHA20_IV_SIZE)
651 		goto out_drop_chacha;
652 	/* Not a stream cipher? */
653 	if (chacha->base.cra_blocksize != 1)
654 		goto out_drop_chacha;
655 
656 	err = -ENAMETOOLONG;
657 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
658 		     "%s(%s,%s)", name, chacha->base.cra_name,
659 		     poly->cra_name) >= CRYPTO_MAX_ALG_NAME)
660 		goto out_drop_chacha;
661 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
662 		     "%s(%s,%s)", name, chacha->base.cra_driver_name,
663 		     poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
664 		goto out_drop_chacha;
665 
666 	inst->alg.base.cra_flags = (chacha->base.cra_flags | poly->cra_flags) &
667 				   CRYPTO_ALG_ASYNC;
668 	inst->alg.base.cra_priority = (chacha->base.cra_priority +
669 				       poly->cra_priority) / 2;
670 	inst->alg.base.cra_blocksize = 1;
671 	inst->alg.base.cra_alignmask = chacha->base.cra_alignmask |
672 				       poly->cra_alignmask;
673 	inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
674 				     ctx->saltlen;
675 	inst->alg.ivsize = ivsize;
676 	inst->alg.chunksize = crypto_skcipher_alg_chunksize(chacha);
677 	inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
678 	inst->alg.init = chachapoly_init;
679 	inst->alg.exit = chachapoly_exit;
680 	inst->alg.encrypt = chachapoly_encrypt;
681 	inst->alg.decrypt = chachapoly_decrypt;
682 	inst->alg.setkey = chachapoly_setkey;
683 	inst->alg.setauthsize = chachapoly_setauthsize;
684 
685 	inst->free = chachapoly_free;
686 
687 	err = aead_register_instance(tmpl, inst);
688 	if (err)
689 		goto out_drop_chacha;
690 
691 out_put_poly:
692 	crypto_mod_put(poly);
693 	return err;
694 
695 out_drop_chacha:
696 	crypto_drop_skcipher(&ctx->chacha);
697 err_drop_poly:
698 	crypto_drop_ahash(&ctx->poly);
699 err_free_inst:
700 	kfree(inst);
701 	goto out_put_poly;
702 }
703 
rfc7539_create(struct crypto_template * tmpl,struct rtattr ** tb)704 static int rfc7539_create(struct crypto_template *tmpl, struct rtattr **tb)
705 {
706 	return chachapoly_create(tmpl, tb, "rfc7539", 12);
707 }
708 
rfc7539esp_create(struct crypto_template * tmpl,struct rtattr ** tb)709 static int rfc7539esp_create(struct crypto_template *tmpl, struct rtattr **tb)
710 {
711 	return chachapoly_create(tmpl, tb, "rfc7539esp", 8);
712 }
713 
714 static struct crypto_template rfc7539_tmpl = {
715 	.name = "rfc7539",
716 	.create = rfc7539_create,
717 	.module = THIS_MODULE,
718 };
719 
720 static struct crypto_template rfc7539esp_tmpl = {
721 	.name = "rfc7539esp",
722 	.create = rfc7539esp_create,
723 	.module = THIS_MODULE,
724 };
725 
chacha20poly1305_module_init(void)726 static int __init chacha20poly1305_module_init(void)
727 {
728 	int err;
729 
730 	err = crypto_register_template(&rfc7539_tmpl);
731 	if (err)
732 		return err;
733 
734 	err = crypto_register_template(&rfc7539esp_tmpl);
735 	if (err)
736 		crypto_unregister_template(&rfc7539_tmpl);
737 
738 	return err;
739 }
740 
chacha20poly1305_module_exit(void)741 static void __exit chacha20poly1305_module_exit(void)
742 {
743 	crypto_unregister_template(&rfc7539esp_tmpl);
744 	crypto_unregister_template(&rfc7539_tmpl);
745 }
746 
747 module_init(chacha20poly1305_module_init);
748 module_exit(chacha20poly1305_module_exit);
749 
750 MODULE_LICENSE("GPL");
751 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
752 MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD");
753 MODULE_ALIAS_CRYPTO("rfc7539");
754 MODULE_ALIAS_CRYPTO("rfc7539esp");
755