2 * GCM: Galois/Counter Mode.
4 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
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.
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>
19 #include "scatterwalk.h"
21 struct gcm_instance_ctx
{
22 struct crypto_spawn ctr
;
25 struct crypto_gcm_ctx
{
26 struct crypto_ablkcipher
*ctr
;
27 struct gf128mul_4k
*gf128
;
30 struct crypto_gcm_ghash_ctx
{
33 struct gf128mul_4k
*gf128
;
37 struct crypto_gcm_req_priv_ctx
{
41 struct crypto_gcm_ghash_ctx ghash
;
44 static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx
*ctx
, u32 flags
,
45 struct gf128mul_4k
*gf128
)
50 memset(ctx
->buffer
, 0, 16);
53 static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx
*ctx
,
54 const u8
*src
, unsigned int srclen
)
56 u8
*dst
= ctx
->buffer
;
59 int n
= min(srclen
, ctx
->bytes
);
60 u8
*pos
= dst
+ (16 - ctx
->bytes
);
69 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
72 while (srclen
>= 16) {
73 crypto_xor(dst
, src
, 16);
74 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
80 ctx
->bytes
= 16 - srclen
;
86 static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx
*ctx
,
87 struct scatterlist
*sg
, int len
)
89 struct scatter_walk walk
;
96 scatterwalk_start(&walk
, sg
);
99 n
= scatterwalk_clamp(&walk
, len
);
102 scatterwalk_start(&walk
, sg_next(walk
.sg
));
103 n
= scatterwalk_clamp(&walk
, len
);
106 src
= scatterwalk_map(&walk
, 0);
108 crypto_gcm_ghash_update(ctx
, src
, n
);
111 scatterwalk_unmap(src
, 0);
112 scatterwalk_advance(&walk
, n
);
113 scatterwalk_done(&walk
, 0, len
);
115 crypto_yield(ctx
->flags
);
119 static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx
*ctx
)
121 u8
*dst
= ctx
->buffer
;
124 u8
*tmp
= dst
+ (16 - ctx
->bytes
);
129 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
135 static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx
*ctx
,
136 unsigned int authlen
,
137 unsigned int cryptlen
, u8
*dst
)
139 u8
*buf
= ctx
->buffer
;
142 lengths
.a
= cpu_to_be64(authlen
* 8);
143 lengths
.b
= cpu_to_be64(cryptlen
* 8);
145 crypto_gcm_ghash_flush(ctx
);
146 crypto_xor(buf
, (u8
*)&lengths
, 16);
147 gf128mul_4k_lle((be128
*)buf
, ctx
->gf128
);
148 crypto_xor(dst
, buf
, 16);
151 static inline void crypto_gcm_set_counter(u8
*counterblock
, u32 value
)
153 *((u32
*)&counterblock
[12]) = cpu_to_be32(value
);
156 static int crypto_gcm_encrypt_counter(struct crypto_aead
*aead
, u8
*block
,
157 u32 value
, const u8
*iv
)
159 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
160 struct crypto_ablkcipher
*ctr
= ctx
->ctr
;
161 struct ablkcipher_request req
;
162 struct scatterlist sg
;
166 memset(counterblock
, 0, 12);
168 memcpy(counterblock
, iv
, 12);
170 crypto_gcm_set_counter(counterblock
, value
);
172 sg_init_one(&sg
, block
, 16);
173 ablkcipher_request_set_tfm(&req
, ctr
);
174 ablkcipher_request_set_crypt(&req
, &sg
, &sg
, 16, counterblock
);
175 ablkcipher_request_set_callback(&req
, 0, NULL
, NULL
);
176 memset(block
, 0, 16);
177 return crypto_ablkcipher_encrypt(&req
);
180 static int crypto_gcm_setkey(struct crypto_aead
*aead
, const u8
*key
,
183 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
184 struct crypto_ablkcipher
*ctr
= ctx
->ctr
;
185 int alignmask
= crypto_ablkcipher_alignmask(ctr
);
186 u8 alignbuf
[16+alignmask
];
187 u8
*hash
= (u8
*)ALIGN((unsigned long)alignbuf
, alignmask
+1);
190 crypto_ablkcipher_clear_flags(ctr
, CRYPTO_TFM_REQ_MASK
);
191 crypto_ablkcipher_set_flags(ctr
, crypto_aead_get_flags(aead
) &
192 CRYPTO_TFM_REQ_MASK
);
194 err
= crypto_ablkcipher_setkey(ctr
, key
, keylen
);
198 crypto_aead_set_flags(aead
, crypto_ablkcipher_get_flags(ctr
) &
199 CRYPTO_TFM_RES_MASK
);
201 err
= crypto_gcm_encrypt_counter(aead
, hash
, -1, NULL
);
205 if (ctx
->gf128
!= NULL
)
206 gf128mul_free_4k(ctx
->gf128
);
208 ctx
->gf128
= gf128mul_init_4k_lle((be128
*)hash
);
210 if (ctx
->gf128
== NULL
)
217 static int crypto_gcm_init_crypt(struct ablkcipher_request
*ablk_req
,
218 struct aead_request
*req
,
219 unsigned int cryptlen
,
220 void (*done
)(struct crypto_async_request
*,
223 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
224 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
225 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
226 u32 flags
= req
->base
.tfm
->crt_flags
;
227 u8
*auth_tag
= pctx
->auth_tag
;
228 u8
*counter
= pctx
->counter
;
229 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
232 ablkcipher_request_set_tfm(ablk_req
, ctx
->ctr
);
233 ablkcipher_request_set_callback(ablk_req
, aead_request_flags(req
),
235 ablkcipher_request_set_crypt(ablk_req
, req
->src
, req
->dst
,
238 err
= crypto_gcm_encrypt_counter(aead
, auth_tag
, 0, req
->iv
);
242 memcpy(counter
, req
->iv
, 12);
243 crypto_gcm_set_counter(counter
, 1);
245 crypto_gcm_ghash_init(ghash
, flags
, ctx
->gf128
);
247 crypto_gcm_ghash_update_sg(ghash
, req
->assoc
, req
->assoclen
);
248 crypto_gcm_ghash_flush(ghash
);
254 static int crypto_gcm_hash(struct aead_request
*req
)
256 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
257 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
258 u8
*auth_tag
= pctx
->auth_tag
;
259 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
261 crypto_gcm_ghash_update_sg(ghash
, req
->dst
, req
->cryptlen
);
262 crypto_gcm_ghash_final_xor(ghash
, req
->assoclen
, req
->cryptlen
,
265 scatterwalk_map_and_copy(auth_tag
, req
->dst
, req
->cryptlen
,
266 crypto_aead_authsize(aead
), 1);
270 static void crypto_gcm_encrypt_done(struct crypto_async_request
*areq
, int err
)
272 struct aead_request
*req
= areq
->data
;
275 err
= crypto_gcm_hash(req
);
277 aead_request_complete(req
, err
);
280 static int crypto_gcm_encrypt(struct aead_request
*req
)
282 struct ablkcipher_request abreq
;
285 err
= crypto_gcm_init_crypt(&abreq
, req
, req
->cryptlen
,
286 crypto_gcm_encrypt_done
);
291 err
= crypto_ablkcipher_encrypt(&abreq
);
296 return crypto_gcm_hash(req
);
299 static void crypto_gcm_decrypt_done(struct crypto_async_request
*areq
, int err
)
301 aead_request_complete(areq
->data
, err
);
304 static int crypto_gcm_decrypt(struct aead_request
*req
)
306 struct ablkcipher_request abreq
;
307 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
308 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
309 u8
*auth_tag
= pctx
->auth_tag
;
310 u8
*iauth_tag
= pctx
->iauth_tag
;
311 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
312 unsigned int cryptlen
= req
->cryptlen
;
313 unsigned int authsize
= crypto_aead_authsize(aead
);
316 if (cryptlen
< authsize
)
318 cryptlen
-= authsize
;
320 err
= crypto_gcm_init_crypt(&abreq
, req
, cryptlen
,
321 crypto_gcm_decrypt_done
);
325 crypto_gcm_ghash_update_sg(ghash
, req
->src
, cryptlen
);
326 crypto_gcm_ghash_final_xor(ghash
, req
->assoclen
, cryptlen
, auth_tag
);
328 scatterwalk_map_and_copy(iauth_tag
, req
->src
, cryptlen
, authsize
, 0);
329 if (memcmp(iauth_tag
, auth_tag
, authsize
))
332 return crypto_ablkcipher_decrypt(&abreq
);
335 static int crypto_gcm_init_tfm(struct crypto_tfm
*tfm
)
337 struct crypto_instance
*inst
= (void *)tfm
->__crt_alg
;
338 struct gcm_instance_ctx
*ictx
= crypto_instance_ctx(inst
);
339 struct crypto_gcm_ctx
*ctx
= crypto_tfm_ctx(tfm
);
340 struct crypto_ablkcipher
*ctr
;
344 ctr
= crypto_spawn_ablkcipher(&ictx
->ctr
);
352 align
= max_t(unsigned long, crypto_ablkcipher_alignmask(ctr
),
353 __alignof__(u32
) - 1);
354 align
&= ~(crypto_tfm_ctx_alignment() - 1);
355 tfm
->crt_aead
.reqsize
= align
+ sizeof(struct crypto_gcm_req_priv_ctx
);
360 static void crypto_gcm_exit_tfm(struct crypto_tfm
*tfm
)
362 struct crypto_gcm_ctx
*ctx
= crypto_tfm_ctx(tfm
);
364 if (ctx
->gf128
!= NULL
)
365 gf128mul_free_4k(ctx
->gf128
);
367 crypto_free_ablkcipher(ctx
->ctr
);
370 static struct crypto_instance
*crypto_gcm_alloc(struct rtattr
**tb
)
372 struct crypto_instance
*inst
;
373 struct crypto_alg
*ctr
;
374 struct crypto_alg
*cipher
;
375 struct gcm_instance_ctx
*ctx
;
377 char ctr_name
[CRYPTO_MAX_ALG_NAME
];
379 err
= crypto_check_attr_type(tb
, CRYPTO_ALG_TYPE_AEAD
);
383 cipher
= crypto_attr_alg(tb
[1], CRYPTO_ALG_TYPE_CIPHER
,
384 CRYPTO_ALG_TYPE_MASK
);
386 inst
= ERR_PTR(PTR_ERR(cipher
));
390 inst
= ERR_PTR(ENAMETOOLONG
);
392 ctr_name
, CRYPTO_MAX_ALG_NAME
,
393 "ctr(%s,0,16,4)", cipher
->cra_name
) >= CRYPTO_MAX_ALG_NAME
)
396 ctr
= crypto_alg_mod_lookup(ctr_name
, CRYPTO_ALG_TYPE_BLKCIPHER
,
397 CRYPTO_ALG_TYPE_MASK
);
400 return ERR_PTR(PTR_ERR(ctr
));
402 if (cipher
->cra_blocksize
!= 16)
405 inst
= kzalloc(sizeof(*inst
) + sizeof(*ctx
), GFP_KERNEL
);
411 if (snprintf(inst
->alg
.cra_name
, CRYPTO_MAX_ALG_NAME
,
412 "gcm(%s)", cipher
->cra_name
) >= CRYPTO_MAX_ALG_NAME
||
413 snprintf(inst
->alg
.cra_driver_name
, CRYPTO_MAX_ALG_NAME
,
414 "gcm(%s)", cipher
->cra_driver_name
) >= CRYPTO_MAX_ALG_NAME
)
418 ctx
= crypto_instance_ctx(inst
);
419 err
= crypto_init_spawn(&ctx
->ctr
, ctr
, inst
, CRYPTO_ALG_TYPE_MASK
);
423 inst
->alg
.cra_flags
= CRYPTO_ALG_TYPE_AEAD
| CRYPTO_ALG_ASYNC
;
424 inst
->alg
.cra_priority
= ctr
->cra_priority
;
425 inst
->alg
.cra_blocksize
= 16;
426 inst
->alg
.cra_alignmask
= __alignof__(u32
) - 1;
427 inst
->alg
.cra_type
= &crypto_aead_type
;
428 inst
->alg
.cra_aead
.ivsize
= 12;
429 inst
->alg
.cra_aead
.maxauthsize
= 16;
430 inst
->alg
.cra_ctxsize
= sizeof(struct crypto_gcm_ctx
);
431 inst
->alg
.cra_init
= crypto_gcm_init_tfm
;
432 inst
->alg
.cra_exit
= crypto_gcm_exit_tfm
;
433 inst
->alg
.cra_aead
.setkey
= crypto_gcm_setkey
;
434 inst
->alg
.cra_aead
.encrypt
= crypto_gcm_encrypt
;
435 inst
->alg
.cra_aead
.decrypt
= crypto_gcm_decrypt
;
447 static void crypto_gcm_free(struct crypto_instance
*inst
)
449 struct gcm_instance_ctx
*ctx
= crypto_instance_ctx(inst
);
451 crypto_drop_spawn(&ctx
->ctr
);
455 static struct crypto_template crypto_gcm_tmpl
= {
457 .alloc
= crypto_gcm_alloc
,
458 .free
= crypto_gcm_free
,
459 .module
= THIS_MODULE
,
462 static int __init
crypto_gcm_module_init(void)
464 return crypto_register_template(&crypto_gcm_tmpl
);
467 static void __exit
crypto_gcm_module_exit(void)
469 crypto_unregister_template(&crypto_gcm_tmpl
);
472 module_init(crypto_gcm_module_init
);
473 module_exit(crypto_gcm_module_exit
);
475 MODULE_LICENSE("GPL");
476 MODULE_DESCRIPTION("Galois/Counter Mode");
477 MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");