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Linux/crypto/authenc.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * Authenc: Simple AEAD wrapper for IPsec
  4  *
  5  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
  6  */
  7 
  8 #include <crypto/internal/aead.h>
  9 #include <crypto/internal/hash.h>
 10 #include <crypto/internal/skcipher.h>
 11 #include <crypto/authenc.h>
 12 #include <crypto/null.h>
 13 #include <crypto/scatterwalk.h>
 14 #include <linux/err.h>
 15 #include <linux/init.h>
 16 #include <linux/kernel.h>
 17 #include <linux/module.h>
 18 #include <linux/rtnetlink.h>
 19 #include <linux/slab.h>
 20 #include <linux/spinlock.h>
 21 
 22 struct authenc_instance_ctx {
 23         struct crypto_ahash_spawn auth;
 24         struct crypto_skcipher_spawn enc;
 25         unsigned int reqoff;
 26 };
 27 
 28 struct crypto_authenc_ctx {
 29         struct crypto_ahash *auth;
 30         struct crypto_skcipher *enc;
 31         struct crypto_sync_skcipher *null;
 32 };
 33 
 34 struct authenc_request_ctx {
 35         struct scatterlist src[2];
 36         struct scatterlist dst[2];
 37         char tail[];
 38 };
 39 
 40 static void authenc_request_complete(struct aead_request *req, int err)
 41 {
 42         if (err != -EINPROGRESS)
 43                 aead_request_complete(req, err);
 44 }
 45 
 46 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
 47                                unsigned int keylen)
 48 {
 49         struct rtattr *rta = (struct rtattr *)key;
 50         struct crypto_authenc_key_param *param;
 51 
 52         if (!RTA_OK(rta, keylen))
 53                 return -EINVAL;
 54         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
 55                 return -EINVAL;
 56 
 57         /*
 58          * RTA_OK() didn't align the rtattr's payload when validating that it
 59          * fits in the buffer.  Yet, the keys should start on the next 4-byte
 60          * aligned boundary.  To avoid confusion, require that the rtattr
 61          * payload be exactly the param struct, which has a 4-byte aligned size.
 62          */
 63         if (RTA_PAYLOAD(rta) != sizeof(*param))
 64                 return -EINVAL;
 65         BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);
 66 
 67         param = RTA_DATA(rta);
 68         keys->enckeylen = be32_to_cpu(param->enckeylen);
 69 
 70         key += rta->rta_len;
 71         keylen -= rta->rta_len;
 72 
 73         if (keylen < keys->enckeylen)
 74                 return -EINVAL;
 75 
 76         keys->authkeylen = keylen - keys->enckeylen;
 77         keys->authkey = key;
 78         keys->enckey = key + keys->authkeylen;
 79 
 80         return 0;
 81 }
 82 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
 83 
 84 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
 85                                  unsigned int keylen)
 86 {
 87         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 88         struct crypto_ahash *auth = ctx->auth;
 89         struct crypto_skcipher *enc = ctx->enc;
 90         struct crypto_authenc_keys keys;
 91         int err = -EINVAL;
 92 
 93         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
 94                 goto badkey;
 95 
 96         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
 97         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
 98                                     CRYPTO_TFM_REQ_MASK);
 99         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
100         crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
101                                        CRYPTO_TFM_RES_MASK);
102 
103         if (err)
104                 goto out;
105 
106         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
107         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
108                                        CRYPTO_TFM_REQ_MASK);
109         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
110         crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &
111                                        CRYPTO_TFM_RES_MASK);
112 
113 out:
114         memzero_explicit(&keys, sizeof(keys));
115         return err;
116 
117 badkey:
118         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
119         goto out;
120 }
121 
122 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
123 {
124         struct aead_request *req = areq->data;
125         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
126         struct aead_instance *inst = aead_alg_instance(authenc);
127         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
128         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
129         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
130 
131         if (err)
132                 goto out;
133 
134         scatterwalk_map_and_copy(ahreq->result, req->dst,
135                                  req->assoclen + req->cryptlen,
136                                  crypto_aead_authsize(authenc), 1);
137 
138 out:
139         aead_request_complete(req, err);
140 }
141 
142 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
143 {
144         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
145         struct aead_instance *inst = aead_alg_instance(authenc);
146         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
147         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
148         struct crypto_ahash *auth = ctx->auth;
149         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
150         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
151         u8 *hash = areq_ctx->tail;
152         int err;
153 
154         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
155                            crypto_ahash_alignmask(auth) + 1);
156 
157         ahash_request_set_tfm(ahreq, auth);
158         ahash_request_set_crypt(ahreq, req->dst, hash,
159                                 req->assoclen + req->cryptlen);
160         ahash_request_set_callback(ahreq, flags,
161                                    authenc_geniv_ahash_done, req);
162 
163         err = crypto_ahash_digest(ahreq);
164         if (err)
165                 return err;
166 
167         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
168                                  crypto_aead_authsize(authenc), 1);
169 
170         return 0;
171 }
172 
173 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
174                                         int err)
175 {
176         struct aead_request *areq = req->data;
177 
178         if (err)
179                 goto out;
180 
181         err = crypto_authenc_genicv(areq, 0);
182 
183 out:
184         authenc_request_complete(areq, err);
185 }
186 
187 static int crypto_authenc_copy_assoc(struct aead_request *req)
188 {
189         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
190         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
191         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
192 
193         skcipher_request_set_sync_tfm(skreq, ctx->null);
194         skcipher_request_set_callback(skreq, aead_request_flags(req),
195                                       NULL, NULL);
196         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
197                                    NULL);
198 
199         return crypto_skcipher_encrypt(skreq);
200 }
201 
202 static int crypto_authenc_encrypt(struct aead_request *req)
203 {
204         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
205         struct aead_instance *inst = aead_alg_instance(authenc);
206         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
207         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
208         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
209         struct crypto_skcipher *enc = ctx->enc;
210         unsigned int cryptlen = req->cryptlen;
211         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
212                                                   ictx->reqoff);
213         struct scatterlist *src, *dst;
214         int err;
215 
216         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
217         dst = src;
218 
219         if (req->src != req->dst) {
220                 err = crypto_authenc_copy_assoc(req);
221                 if (err)
222                         return err;
223 
224                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
225         }
226 
227         skcipher_request_set_tfm(skreq, enc);
228         skcipher_request_set_callback(skreq, aead_request_flags(req),
229                                       crypto_authenc_encrypt_done, req);
230         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
231 
232         err = crypto_skcipher_encrypt(skreq);
233         if (err)
234                 return err;
235 
236         return crypto_authenc_genicv(req, aead_request_flags(req));
237 }
238 
239 static int crypto_authenc_decrypt_tail(struct aead_request *req,
240                                        unsigned int flags)
241 {
242         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
243         struct aead_instance *inst = aead_alg_instance(authenc);
244         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
245         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
246         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
247         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
248         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
249                                                   ictx->reqoff);
250         unsigned int authsize = crypto_aead_authsize(authenc);
251         u8 *ihash = ahreq->result + authsize;
252         struct scatterlist *src, *dst;
253 
254         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
255 
256         if (crypto_memneq(ihash, ahreq->result, authsize))
257                 return -EBADMSG;
258 
259         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
260         dst = src;
261 
262         if (req->src != req->dst)
263                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
264 
265         skcipher_request_set_tfm(skreq, ctx->enc);
266         skcipher_request_set_callback(skreq, aead_request_flags(req),
267                                       req->base.complete, req->base.data);
268         skcipher_request_set_crypt(skreq, src, dst,
269                                    req->cryptlen - authsize, req->iv);
270 
271         return crypto_skcipher_decrypt(skreq);
272 }
273 
274 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
275                                       int err)
276 {
277         struct aead_request *req = areq->data;
278 
279         if (err)
280                 goto out;
281 
282         err = crypto_authenc_decrypt_tail(req, 0);
283 
284 out:
285         authenc_request_complete(req, err);
286 }
287 
288 static int crypto_authenc_decrypt(struct aead_request *req)
289 {
290         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
291         unsigned int authsize = crypto_aead_authsize(authenc);
292         struct aead_instance *inst = aead_alg_instance(authenc);
293         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
294         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
295         struct crypto_ahash *auth = ctx->auth;
296         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
297         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
298         u8 *hash = areq_ctx->tail;
299         int err;
300 
301         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
302                            crypto_ahash_alignmask(auth) + 1);
303 
304         ahash_request_set_tfm(ahreq, auth);
305         ahash_request_set_crypt(ahreq, req->src, hash,
306                                 req->assoclen + req->cryptlen - authsize);
307         ahash_request_set_callback(ahreq, aead_request_flags(req),
308                                    authenc_verify_ahash_done, req);
309 
310         err = crypto_ahash_digest(ahreq);
311         if (err)
312                 return err;
313 
314         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
315 }
316 
317 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
318 {
319         struct aead_instance *inst = aead_alg_instance(tfm);
320         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
321         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
322         struct crypto_ahash *auth;
323         struct crypto_skcipher *enc;
324         struct crypto_sync_skcipher *null;
325         int err;
326 
327         auth = crypto_spawn_ahash(&ictx->auth);
328         if (IS_ERR(auth))
329                 return PTR_ERR(auth);
330 
331         enc = crypto_spawn_skcipher(&ictx->enc);
332         err = PTR_ERR(enc);
333         if (IS_ERR(enc))
334                 goto err_free_ahash;
335 
336         null = crypto_get_default_null_skcipher();
337         err = PTR_ERR(null);
338         if (IS_ERR(null))
339                 goto err_free_skcipher;
340 
341         ctx->auth = auth;
342         ctx->enc = enc;
343         ctx->null = null;
344 
345         crypto_aead_set_reqsize(
346                 tfm,
347                 sizeof(struct authenc_request_ctx) +
348                 ictx->reqoff +
349                 max_t(unsigned int,
350                       crypto_ahash_reqsize(auth) +
351                       sizeof(struct ahash_request),
352                       sizeof(struct skcipher_request) +
353                       crypto_skcipher_reqsize(enc)));
354 
355         return 0;
356 
357 err_free_skcipher:
358         crypto_free_skcipher(enc);
359 err_free_ahash:
360         crypto_free_ahash(auth);
361         return err;
362 }
363 
364 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
365 {
366         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
367 
368         crypto_free_ahash(ctx->auth);
369         crypto_free_skcipher(ctx->enc);
370         crypto_put_default_null_skcipher();
371 }
372 
373 static void crypto_authenc_free(struct aead_instance *inst)
374 {
375         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
376 
377         crypto_drop_skcipher(&ctx->enc);
378         crypto_drop_ahash(&ctx->auth);
379         kfree(inst);
380 }
381 
382 static int crypto_authenc_create(struct crypto_template *tmpl,
383                                  struct rtattr **tb)
384 {
385         struct crypto_attr_type *algt;
386         struct aead_instance *inst;
387         struct hash_alg_common *auth;
388         struct crypto_alg *auth_base;
389         struct skcipher_alg *enc;
390         struct authenc_instance_ctx *ctx;
391         const char *enc_name;
392         int err;
393 
394         algt = crypto_get_attr_type(tb);
395         if (IS_ERR(algt))
396                 return PTR_ERR(algt);
397 
398         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
399                 return -EINVAL;
400 
401         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
402                               CRYPTO_ALG_TYPE_AHASH_MASK |
403                               crypto_requires_sync(algt->type, algt->mask));
404         if (IS_ERR(auth))
405                 return PTR_ERR(auth);
406 
407         auth_base = &auth->base;
408 
409         enc_name = crypto_attr_alg_name(tb[2]);
410         err = PTR_ERR(enc_name);
411         if (IS_ERR(enc_name))
412                 goto out_put_auth;
413 
414         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
415         err = -ENOMEM;
416         if (!inst)
417                 goto out_put_auth;
418 
419         ctx = aead_instance_ctx(inst);
420 
421         err = crypto_init_ahash_spawn(&ctx->auth, auth,
422                                       aead_crypto_instance(inst));
423         if (err)
424                 goto err_free_inst;
425 
426         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
427         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
428                                    crypto_requires_sync(algt->type,
429                                                         algt->mask));
430         if (err)
431                 goto err_drop_auth;
432 
433         enc = crypto_spawn_skcipher_alg(&ctx->enc);
434 
435         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
436                             auth_base->cra_alignmask + 1);
437 
438         err = -ENAMETOOLONG;
439         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
440                      "authenc(%s,%s)", auth_base->cra_name,
441                      enc->base.cra_name) >=
442             CRYPTO_MAX_ALG_NAME)
443                 goto err_drop_enc;
444 
445         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
446                      "authenc(%s,%s)", auth_base->cra_driver_name,
447                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
448                 goto err_drop_enc;
449 
450         inst->alg.base.cra_flags = (auth_base->cra_flags |
451                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
452         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
453                                       auth_base->cra_priority;
454         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
455         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
456                                        enc->base.cra_alignmask;
457         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
458 
459         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
460         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
461         inst->alg.maxauthsize = auth->digestsize;
462 
463         inst->alg.init = crypto_authenc_init_tfm;
464         inst->alg.exit = crypto_authenc_exit_tfm;
465 
466         inst->alg.setkey = crypto_authenc_setkey;
467         inst->alg.encrypt = crypto_authenc_encrypt;
468         inst->alg.decrypt = crypto_authenc_decrypt;
469 
470         inst->free = crypto_authenc_free;
471 
472         err = aead_register_instance(tmpl, inst);
473         if (err)
474                 goto err_drop_enc;
475 
476 out:
477         crypto_mod_put(auth_base);
478         return err;
479 
480 err_drop_enc:
481         crypto_drop_skcipher(&ctx->enc);
482 err_drop_auth:
483         crypto_drop_ahash(&ctx->auth);
484 err_free_inst:
485         kfree(inst);
486 out_put_auth:
487         goto out;
488 }
489 
490 static struct crypto_template crypto_authenc_tmpl = {
491         .name = "authenc",
492         .create = crypto_authenc_create,
493         .module = THIS_MODULE,
494 };
495 
496 static int __init crypto_authenc_module_init(void)
497 {
498         return crypto_register_template(&crypto_authenc_tmpl);
499 }
500 
501 static void __exit crypto_authenc_module_exit(void)
502 {
503         crypto_unregister_template(&crypto_authenc_tmpl);
504 }
505 
506 subsys_initcall(crypto_authenc_module_init);
507 module_exit(crypto_authenc_module_exit);
508 
509 MODULE_LICENSE("GPL");
510 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
511 MODULE_ALIAS_CRYPTO("authenc");
512 

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