2 * echainiv: Encrypted Chain IV Generator
4 * This generator generates an IV based on a sequence number by xoring it
5 * with a salt and then encrypting it with the same key as used to encrypt
6 * the plain text. This algorithm requires that the block size be equal
7 * to the IV size. It is mainly useful for CBC.
9 * This generator can only be used by algorithms where authentication
10 * is performed after encryption (i.e., authenc).
12 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the Free
16 * Software Foundation; either version 2 of the License, or (at your option)
21 #include <crypto/internal/aead.h>
22 #include <crypto/null.h>
23 #include <crypto/rng.h>
24 #include <crypto/scatterwalk.h>
25 #include <linux/err.h>
26 #include <linux/init.h>
27 #include <linux/kernel.h>
29 #include <linux/module.h>
30 #include <linux/percpu.h>
31 #include <linux/spinlock.h>
32 #include <linux/string.h>
34 #define MAX_IV_SIZE 16
36 struct echainiv_request_ctx {
37 struct scatterlist src[2];
38 struct scatterlist dst[2];
39 struct scatterlist ivbuf[2];
40 struct scatterlist *ivsg;
41 struct aead_givcrypt_request subreq;
45 struct crypto_aead *child;
47 struct crypto_blkcipher *null;
48 u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
51 static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
53 static int echainiv_setkey(struct crypto_aead *tfm,
54 const u8 *key, unsigned int keylen)
56 struct echainiv_ctx *ctx = crypto_aead_ctx(tfm);
58 return crypto_aead_setkey(ctx->child, key, keylen);
61 static int echainiv_setauthsize(struct crypto_aead *tfm,
62 unsigned int authsize)
64 struct echainiv_ctx *ctx = crypto_aead_ctx(tfm);
66 return crypto_aead_setauthsize(ctx->child, authsize);
69 /* We don't care if we get preempted and read/write IVs from the next CPU. */
70 static void echainiv_read_iv(u8 *dst, unsigned size)
73 u32 __percpu *b = echainiv_iv;
75 for (; size >= 4; size -= 4) {
76 *a++ = this_cpu_read(*b);
81 static void echainiv_write_iv(const u8 *src, unsigned size)
83 const u32 *a = (const u32 *)src;
84 u32 __percpu *b = echainiv_iv;
86 for (; size >= 4; size -= 4) {
87 this_cpu_write(*b, *a);
93 static void echainiv_encrypt_compat_complete2(struct aead_request *req,
96 struct echainiv_request_ctx *rctx = aead_request_ctx(req);
97 struct aead_givcrypt_request *subreq = &rctx->subreq;
98 struct crypto_aead *geniv;
100 if (err == -EINPROGRESS)
106 geniv = crypto_aead_reqtfm(req);
107 scatterwalk_map_and_copy(subreq->giv, rctx->ivsg, 0,
108 crypto_aead_ivsize(geniv), 1);
114 static void echainiv_encrypt_compat_complete(
115 struct crypto_async_request *base, int err)
117 struct aead_request *req = base->data;
119 echainiv_encrypt_compat_complete2(req, err);
120 aead_request_complete(req, err);
123 static void echainiv_encrypt_complete2(struct aead_request *req, int err)
125 struct aead_request *subreq = aead_request_ctx(req);
126 struct crypto_aead *geniv;
129 if (err == -EINPROGRESS)
135 geniv = crypto_aead_reqtfm(req);
136 ivsize = crypto_aead_ivsize(geniv);
138 echainiv_write_iv(subreq->iv, ivsize);
140 if (req->iv != subreq->iv)
141 memcpy(req->iv, subreq->iv, ivsize);
144 if (req->iv != subreq->iv)
148 static void echainiv_encrypt_complete(struct crypto_async_request *base,
151 struct aead_request *req = base->data;
153 echainiv_encrypt_complete2(req, err);
154 aead_request_complete(req, err);
157 static int echainiv_encrypt_compat(struct aead_request *req)
159 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
160 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
161 struct echainiv_request_ctx *rctx = aead_request_ctx(req);
162 struct aead_givcrypt_request *subreq = &rctx->subreq;
163 unsigned int ivsize = crypto_aead_ivsize(geniv);
164 crypto_completion_t compl;
170 if (req->cryptlen < ivsize)
173 compl = req->base.complete;
174 data = req->base.data;
176 rctx->ivsg = scatterwalk_ffwd(rctx->ivbuf, req->dst, req->assoclen);
177 info = PageHighMem(sg_page(rctx->ivsg)) ? NULL : sg_virt(rctx->ivsg);
180 info = kmalloc(ivsize, req->base.flags &
181 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
186 compl = echainiv_encrypt_compat_complete;
190 memcpy(&seq, req->iv + ivsize - sizeof(seq), sizeof(seq));
192 aead_givcrypt_set_tfm(subreq, ctx->child);
193 aead_givcrypt_set_callback(subreq, req->base.flags,
194 req->base.complete, req->base.data);
195 aead_givcrypt_set_crypt(subreq,
196 scatterwalk_ffwd(rctx->src, req->src,
197 req->assoclen + ivsize),
198 scatterwalk_ffwd(rctx->dst, rctx->ivsg,
200 req->cryptlen - ivsize, req->iv);
201 aead_givcrypt_set_assoc(subreq, req->src, req->assoclen);
202 aead_givcrypt_set_giv(subreq, info, be64_to_cpu(seq));
204 err = crypto_aead_givencrypt(subreq);
205 if (unlikely(PageHighMem(sg_page(rctx->ivsg))))
206 echainiv_encrypt_compat_complete2(req, err);
210 static int echainiv_encrypt(struct aead_request *req)
212 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
213 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
214 struct aead_request *subreq = aead_request_ctx(req);
215 crypto_completion_t compl;
218 unsigned int ivsize = crypto_aead_ivsize(geniv);
221 if (req->cryptlen < ivsize)
224 aead_request_set_tfm(subreq, ctx->child);
226 compl = echainiv_encrypt_complete;
230 if (req->src != req->dst) {
231 struct scatterlist src[2];
232 struct scatterlist dst[2];
233 struct blkcipher_desc desc = {
237 err = crypto_blkcipher_encrypt(
239 scatterwalk_ffwd(dst, req->dst,
240 req->assoclen + ivsize),
241 scatterwalk_ffwd(src, req->src,
242 req->assoclen + ivsize),
243 req->cryptlen - ivsize);
248 if (unlikely(!IS_ALIGNED((unsigned long)info,
249 crypto_aead_alignmask(geniv) + 1))) {
250 info = kmalloc(ivsize, req->base.flags &
251 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
256 memcpy(info, req->iv, ivsize);
259 aead_request_set_callback(subreq, req->base.flags, compl, data);
260 aead_request_set_crypt(subreq, req->dst, req->dst,
261 req->cryptlen - ivsize, info);
262 aead_request_set_ad(subreq, req->assoclen + ivsize, 0);
264 crypto_xor(info, ctx->salt, ivsize);
265 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
266 echainiv_read_iv(info, ivsize);
268 err = crypto_aead_encrypt(subreq);
269 echainiv_encrypt_complete2(req, err);
273 static int echainiv_decrypt_compat(struct aead_request *req)
275 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
276 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
277 struct echainiv_request_ctx *rctx = aead_request_ctx(req);
278 struct aead_request *subreq = &rctx->subreq.areq;
279 crypto_completion_t compl;
281 unsigned int ivsize = crypto_aead_ivsize(geniv);
283 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
286 aead_request_set_tfm(subreq, ctx->child);
288 compl = req->base.complete;
289 data = req->base.data;
291 aead_request_set_callback(subreq, req->base.flags, compl, data);
292 aead_request_set_crypt(subreq,
293 scatterwalk_ffwd(rctx->src, req->src,
294 req->assoclen + ivsize),
295 scatterwalk_ffwd(rctx->dst, req->dst,
296 req->assoclen + ivsize),
297 req->cryptlen - ivsize, req->iv);
298 aead_request_set_assoc(subreq, req->src, req->assoclen);
300 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
302 return crypto_aead_decrypt(subreq);
305 static int echainiv_decrypt(struct aead_request *req)
307 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
308 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
309 struct aead_request *subreq = aead_request_ctx(req);
310 crypto_completion_t compl;
312 unsigned int ivsize = crypto_aead_ivsize(geniv);
314 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
317 aead_request_set_tfm(subreq, ctx->child);
319 compl = req->base.complete;
320 data = req->base.data;
322 aead_request_set_callback(subreq, req->base.flags, compl, data);
323 aead_request_set_crypt(subreq, req->src, req->dst,
324 req->cryptlen - ivsize, req->iv);
325 aead_request_set_ad(subreq, req->assoclen + ivsize, 0);
327 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
328 if (req->src != req->dst)
329 scatterwalk_map_and_copy(req->iv, req->dst,
330 req->assoclen, ivsize, 1);
332 return crypto_aead_decrypt(subreq);
335 static int echainiv_encrypt_compat_first(struct aead_request *req)
337 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
338 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
341 spin_lock_bh(&ctx->lock);
342 if (geniv->encrypt != echainiv_encrypt_compat_first)
345 geniv->encrypt = echainiv_encrypt_compat;
346 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
347 crypto_aead_ivsize(geniv));
350 spin_unlock_bh(&ctx->lock);
355 return echainiv_encrypt_compat(req);
358 static int echainiv_encrypt_first(struct aead_request *req)
360 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
361 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
364 spin_lock_bh(&ctx->lock);
365 if (geniv->encrypt != echainiv_encrypt_first)
368 geniv->encrypt = echainiv_encrypt;
369 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
370 crypto_aead_ivsize(geniv));
373 spin_unlock_bh(&ctx->lock);
378 return echainiv_encrypt(req);
381 static int echainiv_compat_init(struct crypto_tfm *tfm)
383 struct crypto_aead *geniv = __crypto_aead_cast(tfm);
384 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
387 spin_lock_init(&ctx->lock);
389 crypto_aead_set_reqsize(geniv, sizeof(struct echainiv_request_ctx));
391 err = aead_geniv_init(tfm);
393 ctx->child = geniv->child;
394 geniv->child = geniv;
399 static int echainiv_init(struct crypto_tfm *tfm)
401 struct crypto_aead *geniv = __crypto_aead_cast(tfm);
402 struct echainiv_ctx *ctx = crypto_aead_ctx(geniv);
405 spin_lock_init(&ctx->lock);
407 crypto_aead_set_reqsize(geniv, sizeof(struct aead_request));
409 ctx->null = crypto_get_default_null_skcipher();
410 err = PTR_ERR(ctx->null);
411 if (IS_ERR(ctx->null))
414 err = aead_geniv_init(tfm);
418 ctx->child = geniv->child;
419 geniv->child = geniv;
425 crypto_put_default_null_skcipher();
429 static void echainiv_compat_exit(struct crypto_tfm *tfm)
431 struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
433 crypto_free_aead(ctx->child);
436 static void echainiv_exit(struct crypto_tfm *tfm)
438 struct echainiv_ctx *ctx = crypto_tfm_ctx(tfm);
440 crypto_free_aead(ctx->child);
441 crypto_put_default_null_skcipher();
444 static int echainiv_aead_create(struct crypto_template *tmpl,
447 struct aead_instance *inst;
448 struct crypto_aead_spawn *spawn;
449 struct aead_alg *alg;
452 inst = aead_geniv_alloc(tmpl, tb, 0, 0);
455 return PTR_ERR(inst);
458 if (inst->alg.ivsize < sizeof(u64) ||
459 inst->alg.ivsize & (sizeof(u32) - 1) ||
460 inst->alg.ivsize > MAX_IV_SIZE)
463 spawn = aead_instance_ctx(inst);
464 alg = crypto_spawn_aead_alg(spawn);
466 inst->alg.setkey = echainiv_setkey;
467 inst->alg.setauthsize = echainiv_setauthsize;
468 inst->alg.encrypt = echainiv_encrypt_first;
469 inst->alg.decrypt = echainiv_decrypt;
471 inst->alg.base.cra_init = echainiv_init;
472 inst->alg.base.cra_exit = echainiv_exit;
474 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
475 inst->alg.base.cra_ctxsize = sizeof(struct echainiv_ctx);
476 inst->alg.base.cra_ctxsize += inst->alg.base.cra_aead.ivsize;
478 if (alg->base.cra_aead.encrypt) {
479 inst->alg.encrypt = echainiv_encrypt_compat_first;
480 inst->alg.decrypt = echainiv_decrypt_compat;
482 inst->alg.base.cra_init = echainiv_compat_init;
483 inst->alg.base.cra_exit = echainiv_compat_exit;
486 err = aead_register_instance(tmpl, inst);
494 aead_geniv_free(inst);
498 static int echainiv_create(struct crypto_template *tmpl, struct rtattr **tb)
502 err = crypto_get_default_rng();
506 err = echainiv_aead_create(tmpl, tb);
514 crypto_put_default_rng();
518 static void echainiv_free(struct crypto_instance *inst)
520 aead_geniv_free(aead_instance(inst));
521 crypto_put_default_rng();
524 static struct crypto_template echainiv_tmpl = {
526 .create = echainiv_create,
527 .free = echainiv_free,
528 .module = THIS_MODULE,
531 static int __init echainiv_module_init(void)
533 return crypto_register_template(&echainiv_tmpl);
536 static void __exit echainiv_module_exit(void)
538 crypto_unregister_template(&echainiv_tmpl);
541 module_init(echainiv_module_init);
542 module_exit(echainiv_module_exit);
544 MODULE_LICENSE("GPL");
545 MODULE_DESCRIPTION("Encrypted Chain IV Generator");
546 MODULE_ALIAS_CRYPTO("echainiv");