Commit | Line | Data |
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28db8e3e MH |
1 | /* |
2 | * GCM: Galois/Counter Mode. | |
3 | * | |
4 | * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License version 2 as published | |
8 | * by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <crypto/algapi.h> | |
12 | #include <crypto/gf128mul.h> | |
13 | #include <linux/err.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/kernel.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/slab.h> | |
18 | ||
19 | #include "scatterwalk.h" | |
20 | ||
21 | struct gcm_instance_ctx { | |
22 | struct crypto_spawn ctr; | |
23 | }; | |
24 | ||
25 | struct crypto_gcm_ctx { | |
26 | struct crypto_ablkcipher *ctr; | |
27 | struct gf128mul_4k *gf128; | |
28 | }; | |
29 | ||
30 | struct crypto_gcm_ghash_ctx { | |
31 | u32 bytes; | |
32 | u32 flags; | |
33 | struct gf128mul_4k *gf128; | |
34 | u8 buffer[16]; | |
35 | }; | |
36 | ||
37 | struct crypto_gcm_req_priv_ctx { | |
38 | u8 auth_tag[16]; | |
39 | u8 counter[16]; | |
40 | struct crypto_gcm_ghash_ctx ghash; | |
41 | }; | |
42 | ||
43 | static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx *ctx, u32 flags, | |
44 | struct gf128mul_4k *gf128) | |
45 | { | |
46 | ctx->bytes = 0; | |
47 | ctx->flags = flags; | |
48 | ctx->gf128 = gf128; | |
49 | memset(ctx->buffer, 0, 16); | |
50 | } | |
51 | ||
52 | static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx *ctx, | |
53 | const u8 *src, unsigned int srclen) | |
54 | { | |
55 | u8 *dst = ctx->buffer; | |
56 | ||
57 | if (ctx->bytes) { | |
58 | int n = min(srclen, ctx->bytes); | |
59 | u8 *pos = dst + (16 - ctx->bytes); | |
60 | ||
61 | ctx->bytes -= n; | |
62 | srclen -= n; | |
63 | ||
64 | while (n--) | |
65 | *pos++ ^= *src++; | |
66 | ||
67 | if (!ctx->bytes) | |
68 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
69 | } | |
70 | ||
71 | while (srclen >= 16) { | |
72 | crypto_xor(dst, src, 16); | |
73 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
74 | src += 16; | |
75 | srclen -= 16; | |
76 | } | |
77 | ||
78 | if (srclen) { | |
79 | ctx->bytes = 16 - srclen; | |
80 | while (srclen--) | |
81 | *dst++ ^= *src++; | |
82 | } | |
83 | } | |
84 | ||
85 | static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx *ctx, | |
86 | struct scatterlist *sg, int len) | |
87 | { | |
88 | struct scatter_walk walk; | |
89 | u8 *src; | |
90 | int n; | |
91 | ||
92 | scatterwalk_start(&walk, sg); | |
93 | ||
94 | while (len) { | |
95 | n = scatterwalk_clamp(&walk, len); | |
96 | ||
97 | if (!n) { | |
98 | scatterwalk_start(&walk, sg_next(walk.sg)); | |
99 | n = scatterwalk_clamp(&walk, len); | |
100 | } | |
101 | ||
102 | src = scatterwalk_map(&walk, 0); | |
103 | ||
104 | crypto_gcm_ghash_update(ctx, src, n); | |
105 | len -= n; | |
106 | ||
107 | scatterwalk_unmap(src, 0); | |
108 | scatterwalk_advance(&walk, n); | |
109 | scatterwalk_done(&walk, 0, len); | |
110 | if (len) | |
111 | crypto_yield(ctx->flags); | |
112 | } | |
113 | } | |
114 | ||
115 | static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx *ctx) | |
116 | { | |
117 | u8 *dst = ctx->buffer; | |
118 | ||
119 | if (ctx->bytes) { | |
120 | u8 *tmp = dst + (16 - ctx->bytes); | |
121 | ||
122 | while (ctx->bytes--) | |
123 | *tmp++ ^= 0; | |
124 | ||
125 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
126 | } | |
127 | ||
128 | ctx->bytes = 0; | |
129 | } | |
130 | ||
131 | static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx *ctx, | |
132 | unsigned int authlen, | |
133 | unsigned int cryptlen, u8 *dst) | |
134 | { | |
135 | u8 *buf = ctx->buffer; | |
136 | u128 lengths; | |
137 | ||
138 | lengths.a = cpu_to_be64(authlen * 8); | |
139 | lengths.b = cpu_to_be64(cryptlen * 8); | |
140 | ||
141 | crypto_gcm_ghash_flush(ctx); | |
142 | crypto_xor(buf, (u8 *)&lengths, 16); | |
143 | gf128mul_4k_lle((be128 *)buf, ctx->gf128); | |
144 | crypto_xor(dst, buf, 16); | |
145 | } | |
146 | ||
147 | static inline void crypto_gcm_set_counter(u8 *counterblock, u32 value) | |
148 | { | |
149 | *((u32 *)&counterblock[12]) = cpu_to_be32(value); | |
150 | } | |
151 | ||
152 | static int crypto_gcm_encrypt_counter(struct crypto_aead *aead, u8 *block, | |
153 | u32 value, const u8 *iv) | |
154 | { | |
155 | struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead); | |
156 | struct crypto_ablkcipher *ctr = ctx->ctr; | |
157 | struct ablkcipher_request req; | |
158 | struct scatterlist sg; | |
159 | u8 counterblock[16]; | |
160 | ||
161 | if (iv == NULL) | |
162 | memset(counterblock, 0, 12); | |
163 | else | |
164 | memcpy(counterblock, iv, 12); | |
165 | ||
166 | crypto_gcm_set_counter(counterblock, value); | |
167 | ||
168 | sg_init_one(&sg, block, 16); | |
169 | ablkcipher_request_set_tfm(&req, ctr); | |
170 | ablkcipher_request_set_crypt(&req, &sg, &sg, 16, counterblock); | |
171 | ablkcipher_request_set_callback(&req, 0, NULL, NULL); | |
172 | memset(block, 0, 16); | |
173 | return crypto_ablkcipher_encrypt(&req); | |
174 | } | |
175 | ||
176 | static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key, | |
177 | unsigned int keylen) | |
178 | { | |
179 | struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead); | |
180 | struct crypto_ablkcipher *ctr = ctx->ctr; | |
181 | int alignmask = crypto_ablkcipher_alignmask(ctr); | |
182 | u8 alignbuf[16+alignmask]; | |
183 | u8 *hash = (u8 *)ALIGN((unsigned long)alignbuf, alignmask+1); | |
184 | int err = 0; | |
185 | ||
186 | crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK); | |
187 | crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) & | |
188 | CRYPTO_TFM_REQ_MASK); | |
189 | ||
190 | err = crypto_ablkcipher_setkey(ctr, key, keylen); | |
191 | if (err) | |
192 | goto out; | |
193 | ||
194 | crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) & | |
195 | CRYPTO_TFM_RES_MASK); | |
196 | ||
197 | err = crypto_gcm_encrypt_counter(aead, hash, -1, NULL); | |
198 | if (err) | |
199 | goto out; | |
200 | ||
201 | if (ctx->gf128 != NULL) | |
202 | gf128mul_free_4k(ctx->gf128); | |
203 | ||
204 | ctx->gf128 = gf128mul_init_4k_lle((be128 *)hash); | |
205 | ||
206 | if (ctx->gf128 == NULL) | |
207 | err = -ENOMEM; | |
208 | ||
209 | out: | |
210 | return err; | |
211 | } | |
212 | ||
213 | static int crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req, | |
214 | struct aead_request *req, | |
215 | void (*done)(struct crypto_async_request *, | |
216 | int)) | |
217 | { | |
218 | struct crypto_aead *aead = crypto_aead_reqtfm(req); | |
219 | struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead); | |
220 | struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req); | |
221 | u32 flags = req->base.tfm->crt_flags; | |
222 | u8 *auth_tag = pctx->auth_tag; | |
223 | u8 *counter = pctx->counter; | |
224 | struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash; | |
225 | int err = 0; | |
226 | ||
227 | ablkcipher_request_set_tfm(ablk_req, ctx->ctr); | |
228 | ablkcipher_request_set_callback(ablk_req, aead_request_flags(req), | |
229 | done, req); | |
230 | ablkcipher_request_set_crypt(ablk_req, req->src, req->dst, | |
231 | req->cryptlen, counter); | |
232 | ||
233 | err = crypto_gcm_encrypt_counter(aead, auth_tag, 0, req->iv); | |
234 | if (err) | |
235 | goto out; | |
236 | ||
237 | memcpy(counter, req->iv, 12); | |
238 | crypto_gcm_set_counter(counter, 1); | |
239 | ||
240 | crypto_gcm_ghash_init(ghash, flags, ctx->gf128); | |
241 | ||
242 | if (req->assoclen) { | |
243 | crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen); | |
244 | crypto_gcm_ghash_flush(ghash); | |
245 | } | |
246 | ||
247 | out: | |
248 | return err; | |
249 | } | |
250 | ||
251 | static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err) | |
252 | { | |
253 | struct aead_request *req = areq->data; | |
254 | struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req); | |
255 | u8 *auth_tag = pctx->auth_tag; | |
256 | struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash; | |
257 | ||
258 | crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen); | |
259 | crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen, | |
260 | auth_tag); | |
261 | ||
262 | aead_request_complete(req, err); | |
263 | } | |
264 | ||
265 | static int crypto_gcm_encrypt(struct aead_request *req) | |
266 | { | |
267 | struct ablkcipher_request abreq; | |
268 | struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req); | |
269 | u8 *auth_tag = pctx->auth_tag; | |
270 | struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash; | |
271 | int err = 0; | |
272 | ||
273 | err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_encrypt_done); | |
274 | if (err) | |
275 | return err; | |
276 | ||
277 | if (req->cryptlen) { | |
278 | err = crypto_ablkcipher_encrypt(&abreq); | |
279 | if (err) | |
280 | return err; | |
281 | ||
282 | crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen); | |
283 | } | |
284 | ||
285 | crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen, | |
286 | auth_tag); | |
287 | ||
288 | return err; | |
289 | } | |
290 | ||
291 | static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err) | |
292 | { | |
293 | aead_request_complete(areq->data, err); | |
294 | } | |
295 | ||
296 | static int crypto_gcm_decrypt(struct aead_request *req) | |
297 | { | |
298 | struct ablkcipher_request abreq; | |
299 | struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req); | |
300 | u8 *auth_tag = pctx->auth_tag; | |
301 | struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash; | |
302 | u8 tag[16]; | |
303 | int err; | |
304 | ||
305 | if (!req->cryptlen) | |
306 | return -EINVAL; | |
307 | ||
308 | memcpy(tag, auth_tag, 16); | |
309 | err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_decrypt_done); | |
310 | if (err) | |
311 | return err; | |
312 | ||
313 | crypto_gcm_ghash_update_sg(ghash, req->src, req->cryptlen); | |
314 | crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen, | |
315 | auth_tag); | |
316 | ||
317 | if (memcmp(tag, auth_tag, 16)) | |
318 | return -EINVAL; | |
319 | ||
320 | return crypto_ablkcipher_decrypt(&abreq); | |
321 | } | |
322 | ||
323 | static int crypto_gcm_init_tfm(struct crypto_tfm *tfm) | |
324 | { | |
325 | struct crypto_instance *inst = (void *)tfm->__crt_alg; | |
326 | struct gcm_instance_ctx *ictx = crypto_instance_ctx(inst); | |
327 | struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm); | |
328 | struct crypto_ablkcipher *ctr; | |
329 | unsigned long align; | |
330 | int err; | |
331 | ||
332 | ctr = crypto_spawn_ablkcipher(&ictx->ctr); | |
333 | err = PTR_ERR(ctr); | |
334 | if (IS_ERR(ctr)) | |
335 | return err; | |
336 | ||
337 | ctx->ctr = ctr; | |
338 | ctx->gf128 = NULL; | |
339 | ||
340 | align = max_t(unsigned long, crypto_ablkcipher_alignmask(ctr), | |
341 | __alignof__(u32) - 1); | |
342 | align &= ~(crypto_tfm_ctx_alignment() - 1); | |
343 | tfm->crt_aead.reqsize = align + sizeof(struct crypto_gcm_req_priv_ctx); | |
344 | ||
345 | return 0; | |
346 | } | |
347 | ||
348 | static void crypto_gcm_exit_tfm(struct crypto_tfm *tfm) | |
349 | { | |
350 | struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm); | |
351 | ||
352 | if (ctx->gf128 != NULL) | |
353 | gf128mul_free_4k(ctx->gf128); | |
354 | ||
355 | crypto_free_ablkcipher(ctx->ctr); | |
356 | } | |
357 | ||
358 | static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb) | |
359 | { | |
360 | struct crypto_instance *inst; | |
361 | struct crypto_alg *ctr; | |
362 | struct crypto_alg *cipher; | |
363 | struct gcm_instance_ctx *ctx; | |
364 | int err; | |
365 | char ctr_name[CRYPTO_MAX_ALG_NAME]; | |
366 | ||
367 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD); | |
368 | if (err) | |
369 | return ERR_PTR(err); | |
370 | ||
371 | cipher = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, | |
372 | CRYPTO_ALG_TYPE_MASK); | |
373 | ||
374 | inst = ERR_PTR(PTR_ERR(cipher)); | |
375 | if (IS_ERR(cipher)) | |
376 | return inst; | |
377 | ||
378 | inst = ERR_PTR(ENAMETOOLONG); | |
379 | if (snprintf( | |
380 | ctr_name, CRYPTO_MAX_ALG_NAME, | |
381 | "ctr(%s,0,16,4)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME) | |
382 | return inst; | |
383 | ||
384 | ctr = crypto_alg_mod_lookup(ctr_name, CRYPTO_ALG_TYPE_BLKCIPHER, | |
385 | CRYPTO_ALG_TYPE_MASK); | |
386 | ||
387 | if (IS_ERR(ctr)) | |
388 | return ERR_PTR(PTR_ERR(ctr)); | |
389 | ||
390 | if (cipher->cra_blocksize != 16) | |
391 | goto out_put_ctr; | |
392 | ||
393 | inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); | |
394 | err = -ENOMEM; | |
395 | if (!inst) | |
396 | goto out_put_ctr; | |
397 | ||
398 | err = -ENAMETOOLONG; | |
399 | if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, | |
400 | "gcm(%s)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME || | |
401 | snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME, | |
402 | "gcm(%s)", cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME) | |
403 | goto err_free_inst; | |
404 | ||
405 | ||
406 | ctx = crypto_instance_ctx(inst); | |
407 | err = crypto_init_spawn(&ctx->ctr, ctr, inst, CRYPTO_ALG_TYPE_MASK); | |
408 | if (err) | |
409 | goto err_free_inst; | |
410 | ||
411 | inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC; | |
412 | inst->alg.cra_priority = ctr->cra_priority; | |
413 | inst->alg.cra_blocksize = 16; | |
414 | inst->alg.cra_alignmask = __alignof__(u32) - 1; | |
415 | inst->alg.cra_type = &crypto_aead_type; | |
416 | inst->alg.cra_aead.ivsize = 12; | |
7ba683a6 | 417 | inst->alg.cra_aead.maxauthsize = 16; |
28db8e3e MH |
418 | inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx); |
419 | inst->alg.cra_init = crypto_gcm_init_tfm; | |
420 | inst->alg.cra_exit = crypto_gcm_exit_tfm; | |
421 | inst->alg.cra_aead.setkey = crypto_gcm_setkey; | |
422 | inst->alg.cra_aead.encrypt = crypto_gcm_encrypt; | |
423 | inst->alg.cra_aead.decrypt = crypto_gcm_decrypt; | |
424 | ||
425 | out: | |
426 | crypto_mod_put(ctr); | |
427 | return inst; | |
428 | err_free_inst: | |
429 | kfree(inst); | |
430 | out_put_ctr: | |
431 | inst = ERR_PTR(err); | |
432 | goto out; | |
433 | } | |
434 | ||
435 | static void crypto_gcm_free(struct crypto_instance *inst) | |
436 | { | |
437 | struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst); | |
438 | ||
439 | crypto_drop_spawn(&ctx->ctr); | |
440 | kfree(inst); | |
441 | } | |
442 | ||
443 | static struct crypto_template crypto_gcm_tmpl = { | |
444 | .name = "gcm", | |
445 | .alloc = crypto_gcm_alloc, | |
446 | .free = crypto_gcm_free, | |
447 | .module = THIS_MODULE, | |
448 | }; | |
449 | ||
450 | static int __init crypto_gcm_module_init(void) | |
451 | { | |
452 | return crypto_register_template(&crypto_gcm_tmpl); | |
453 | } | |
454 | ||
455 | static void __exit crypto_gcm_module_exit(void) | |
456 | { | |
457 | crypto_unregister_template(&crypto_gcm_tmpl); | |
458 | } | |
459 | ||
460 | module_init(crypto_gcm_module_init); | |
461 | module_exit(crypto_gcm_module_exit); | |
462 | ||
463 | MODULE_LICENSE("GPL"); | |
464 | MODULE_DESCRIPTION("Galois/Counter Mode"); | |
465 | MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>"); |