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 <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/slab.h>
22 struct gcm_instance_ctx
{
23 struct crypto_spawn ctr
;
26 struct crypto_gcm_ctx
{
27 struct crypto_ablkcipher
*ctr
;
28 struct gf128mul_4k
*gf128
;
31 struct crypto_gcm_ghash_ctx
{
34 struct gf128mul_4k
*gf128
;
38 struct crypto_gcm_req_priv_ctx
{
42 struct crypto_gcm_ghash_ctx ghash
;
45 static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx
*ctx
, u32 flags
,
46 struct gf128mul_4k
*gf128
)
51 memset(ctx
->buffer
, 0, 16);
54 static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx
*ctx
,
55 const u8
*src
, unsigned int srclen
)
57 u8
*dst
= ctx
->buffer
;
60 int n
= min(srclen
, ctx
->bytes
);
61 u8
*pos
= dst
+ (16 - ctx
->bytes
);
70 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
73 while (srclen
>= 16) {
74 crypto_xor(dst
, src
, 16);
75 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
81 ctx
->bytes
= 16 - srclen
;
87 static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx
*ctx
,
88 struct scatterlist
*sg
, int len
)
90 struct scatter_walk walk
;
97 scatterwalk_start(&walk
, sg
);
100 n
= scatterwalk_clamp(&walk
, len
);
103 scatterwalk_start(&walk
, sg_next(walk
.sg
));
104 n
= scatterwalk_clamp(&walk
, len
);
107 src
= scatterwalk_map(&walk
, 0);
109 crypto_gcm_ghash_update(ctx
, src
, n
);
112 scatterwalk_unmap(src
, 0);
113 scatterwalk_advance(&walk
, n
);
114 scatterwalk_done(&walk
, 0, len
);
116 crypto_yield(ctx
->flags
);
120 static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx
*ctx
)
122 u8
*dst
= ctx
->buffer
;
125 u8
*tmp
= dst
+ (16 - ctx
->bytes
);
130 gf128mul_4k_lle((be128
*)dst
, ctx
->gf128
);
136 static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx
*ctx
,
137 unsigned int authlen
,
138 unsigned int cryptlen
, u8
*dst
)
140 u8
*buf
= ctx
->buffer
;
143 lengths
.a
= cpu_to_be64(authlen
* 8);
144 lengths
.b
= cpu_to_be64(cryptlen
* 8);
146 crypto_gcm_ghash_flush(ctx
);
147 crypto_xor(buf
, (u8
*)&lengths
, 16);
148 gf128mul_4k_lle((be128
*)buf
, ctx
->gf128
);
149 crypto_xor(dst
, buf
, 16);
152 static inline void crypto_gcm_set_counter(u8
*counterblock
, u32 value
)
154 *((u32
*)&counterblock
[12]) = cpu_to_be32(value
);
157 static int crypto_gcm_encrypt_counter(struct crypto_aead
*aead
, u8
*block
,
158 u32 value
, const u8
*iv
)
160 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
161 struct crypto_ablkcipher
*ctr
= ctx
->ctr
;
162 struct ablkcipher_request req
;
163 struct scatterlist sg
;
167 memset(counterblock
, 0, 12);
169 memcpy(counterblock
, iv
, 12);
171 crypto_gcm_set_counter(counterblock
, value
);
173 sg_init_one(&sg
, block
, 16);
174 ablkcipher_request_set_tfm(&req
, ctr
);
175 ablkcipher_request_set_crypt(&req
, &sg
, &sg
, 16, counterblock
);
176 ablkcipher_request_set_callback(&req
, 0, NULL
, NULL
);
177 memset(block
, 0, 16);
178 return crypto_ablkcipher_encrypt(&req
);
181 static int crypto_gcm_setkey(struct crypto_aead
*aead
, const u8
*key
,
184 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
185 struct crypto_ablkcipher
*ctr
= ctx
->ctr
;
186 int alignmask
= crypto_ablkcipher_alignmask(ctr
);
187 u8 alignbuf
[16+alignmask
];
188 u8
*hash
= (u8
*)ALIGN((unsigned long)alignbuf
, alignmask
+1);
191 crypto_ablkcipher_clear_flags(ctr
, CRYPTO_TFM_REQ_MASK
);
192 crypto_ablkcipher_set_flags(ctr
, crypto_aead_get_flags(aead
) &
193 CRYPTO_TFM_REQ_MASK
);
195 err
= crypto_ablkcipher_setkey(ctr
, key
, keylen
);
199 crypto_aead_set_flags(aead
, crypto_ablkcipher_get_flags(ctr
) &
200 CRYPTO_TFM_RES_MASK
);
202 err
= crypto_gcm_encrypt_counter(aead
, hash
, -1, NULL
);
206 if (ctx
->gf128
!= NULL
)
207 gf128mul_free_4k(ctx
->gf128
);
209 ctx
->gf128
= gf128mul_init_4k_lle((be128
*)hash
);
211 if (ctx
->gf128
== NULL
)
218 static int crypto_gcm_init_crypt(struct ablkcipher_request
*ablk_req
,
219 struct aead_request
*req
,
220 unsigned int cryptlen
,
221 void (*done
)(struct crypto_async_request
*,
224 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
225 struct crypto_gcm_ctx
*ctx
= crypto_aead_ctx(aead
);
226 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
227 u32 flags
= req
->base
.tfm
->crt_flags
;
228 u8
*auth_tag
= pctx
->auth_tag
;
229 u8
*counter
= pctx
->counter
;
230 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
233 ablkcipher_request_set_tfm(ablk_req
, ctx
->ctr
);
234 ablkcipher_request_set_callback(ablk_req
, aead_request_flags(req
),
236 ablkcipher_request_set_crypt(ablk_req
, req
->src
, req
->dst
,
239 err
= crypto_gcm_encrypt_counter(aead
, auth_tag
, 0, req
->iv
);
243 memcpy(counter
, req
->iv
, 12);
244 crypto_gcm_set_counter(counter
, 1);
246 crypto_gcm_ghash_init(ghash
, flags
, ctx
->gf128
);
248 crypto_gcm_ghash_update_sg(ghash
, req
->assoc
, req
->assoclen
);
249 crypto_gcm_ghash_flush(ghash
);
255 static int crypto_gcm_hash(struct aead_request
*req
)
257 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
258 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
259 u8
*auth_tag
= pctx
->auth_tag
;
260 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
262 crypto_gcm_ghash_update_sg(ghash
, req
->dst
, req
->cryptlen
);
263 crypto_gcm_ghash_final_xor(ghash
, req
->assoclen
, req
->cryptlen
,
266 scatterwalk_map_and_copy(auth_tag
, req
->dst
, req
->cryptlen
,
267 crypto_aead_authsize(aead
), 1);
271 static void crypto_gcm_encrypt_done(struct crypto_async_request
*areq
, int err
)
273 struct aead_request
*req
= areq
->data
;
276 err
= crypto_gcm_hash(req
);
278 aead_request_complete(req
, err
);
281 static int crypto_gcm_encrypt(struct aead_request
*req
)
283 struct ablkcipher_request abreq
;
286 err
= crypto_gcm_init_crypt(&abreq
, req
, req
->cryptlen
,
287 crypto_gcm_encrypt_done
);
292 err
= crypto_ablkcipher_encrypt(&abreq
);
297 return crypto_gcm_hash(req
);
300 static void crypto_gcm_decrypt_done(struct crypto_async_request
*areq
, int err
)
302 aead_request_complete(areq
->data
, err
);
305 static int crypto_gcm_decrypt(struct aead_request
*req
)
307 struct ablkcipher_request abreq
;
308 struct crypto_aead
*aead
= crypto_aead_reqtfm(req
);
309 struct crypto_gcm_req_priv_ctx
*pctx
= aead_request_ctx(req
);
310 u8
*auth_tag
= pctx
->auth_tag
;
311 u8
*iauth_tag
= pctx
->iauth_tag
;
312 struct crypto_gcm_ghash_ctx
*ghash
= &pctx
->ghash
;
313 unsigned int cryptlen
= req
->cryptlen
;
314 unsigned int authsize
= crypto_aead_authsize(aead
);
317 if (cryptlen
< authsize
)
319 cryptlen
-= authsize
;
321 err
= crypto_gcm_init_crypt(&abreq
, req
, cryptlen
,
322 crypto_gcm_decrypt_done
);
326 crypto_gcm_ghash_update_sg(ghash
, req
->src
, cryptlen
);
327 crypto_gcm_ghash_final_xor(ghash
, req
->assoclen
, cryptlen
, auth_tag
);
329 scatterwalk_map_and_copy(iauth_tag
, req
->src
, cryptlen
, authsize
, 0);
330 if (memcmp(iauth_tag
, auth_tag
, authsize
))
333 return crypto_ablkcipher_decrypt(&abreq
);
336 static int crypto_gcm_init_tfm(struct crypto_tfm
*tfm
)
338 struct crypto_instance
*inst
= (void *)tfm
->__crt_alg
;
339 struct gcm_instance_ctx
*ictx
= crypto_instance_ctx(inst
);
340 struct crypto_gcm_ctx
*ctx
= crypto_tfm_ctx(tfm
);
341 struct crypto_ablkcipher
*ctr
;
345 ctr
= crypto_spawn_ablkcipher(&ictx
->ctr
);
353 align
= max_t(unsigned long, crypto_ablkcipher_alignmask(ctr
),
354 __alignof__(u32
) - 1);
355 align
&= ~(crypto_tfm_ctx_alignment() - 1);
356 tfm
->crt_aead
.reqsize
= align
+ sizeof(struct crypto_gcm_req_priv_ctx
);
361 static void crypto_gcm_exit_tfm(struct crypto_tfm
*tfm
)
363 struct crypto_gcm_ctx
*ctx
= crypto_tfm_ctx(tfm
);
365 if (ctx
->gf128
!= NULL
)
366 gf128mul_free_4k(ctx
->gf128
);
368 crypto_free_ablkcipher(ctx
->ctr
);
371 static struct crypto_instance
*crypto_gcm_alloc(struct rtattr
**tb
)
373 struct crypto_instance
*inst
;
374 struct crypto_alg
*ctr
;
375 struct crypto_alg
*cipher
;
376 struct gcm_instance_ctx
*ctx
;
378 char ctr_name
[CRYPTO_MAX_ALG_NAME
];
380 err
= crypto_check_attr_type(tb
, CRYPTO_ALG_TYPE_AEAD
);
384 cipher
= crypto_attr_alg(tb
[1], CRYPTO_ALG_TYPE_CIPHER
,
385 CRYPTO_ALG_TYPE_MASK
);
387 inst
= ERR_PTR(PTR_ERR(cipher
));
391 inst
= ERR_PTR(ENAMETOOLONG
);
393 ctr_name
, CRYPTO_MAX_ALG_NAME
,
394 "ctr(%s,0,16,4)", cipher
->cra_name
) >= CRYPTO_MAX_ALG_NAME
)
397 ctr
= crypto_alg_mod_lookup(ctr_name
, CRYPTO_ALG_TYPE_BLKCIPHER
,
398 CRYPTO_ALG_TYPE_MASK
);
401 return ERR_PTR(PTR_ERR(ctr
));
403 if (cipher
->cra_blocksize
!= 16)
406 inst
= kzalloc(sizeof(*inst
) + sizeof(*ctx
), GFP_KERNEL
);
412 if (snprintf(inst
->alg
.cra_name
, CRYPTO_MAX_ALG_NAME
,
413 "gcm(%s)", cipher
->cra_name
) >= CRYPTO_MAX_ALG_NAME
||
414 snprintf(inst
->alg
.cra_driver_name
, CRYPTO_MAX_ALG_NAME
,
415 "gcm(%s)", cipher
->cra_driver_name
) >= CRYPTO_MAX_ALG_NAME
)
419 ctx
= crypto_instance_ctx(inst
);
420 err
= crypto_init_spawn(&ctx
->ctr
, ctr
, inst
, CRYPTO_ALG_TYPE_MASK
);
424 inst
->alg
.cra_flags
= CRYPTO_ALG_TYPE_AEAD
| CRYPTO_ALG_ASYNC
;
425 inst
->alg
.cra_priority
= ctr
->cra_priority
;
426 inst
->alg
.cra_blocksize
= 16;
427 inst
->alg
.cra_alignmask
= __alignof__(u32
) - 1;
428 inst
->alg
.cra_type
= &crypto_aead_type
;
429 inst
->alg
.cra_aead
.ivsize
= 12;
430 inst
->alg
.cra_aead
.maxauthsize
= 16;
431 inst
->alg
.cra_ctxsize
= sizeof(struct crypto_gcm_ctx
);
432 inst
->alg
.cra_init
= crypto_gcm_init_tfm
;
433 inst
->alg
.cra_exit
= crypto_gcm_exit_tfm
;
434 inst
->alg
.cra_aead
.setkey
= crypto_gcm_setkey
;
435 inst
->alg
.cra_aead
.encrypt
= crypto_gcm_encrypt
;
436 inst
->alg
.cra_aead
.decrypt
= crypto_gcm_decrypt
;
448 static void crypto_gcm_free(struct crypto_instance
*inst
)
450 struct gcm_instance_ctx
*ctx
= crypto_instance_ctx(inst
);
452 crypto_drop_spawn(&ctx
->ctr
);
456 static struct crypto_template crypto_gcm_tmpl
= {
458 .alloc
= crypto_gcm_alloc
,
459 .free
= crypto_gcm_free
,
460 .module
= THIS_MODULE
,
463 static int __init
crypto_gcm_module_init(void)
465 return crypto_register_template(&crypto_gcm_tmpl
);
468 static void __exit
crypto_gcm_module_exit(void)
470 crypto_unregister_template(&crypto_gcm_tmpl
);
473 module_init(crypto_gcm_module_init
);
474 module_exit(crypto_gcm_module_exit
);
476 MODULE_LICENSE("GPL");
477 MODULE_DESCRIPTION("Galois/Counter Mode");
478 MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");