blob: 5681c7957b88b36c1722bd2edaf555b6cb391399 [file] [log] [blame]
/*
* GCM: Galois/Counter Mode.
*
* Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include <crypto/algapi.h>
#include <crypto/gf128mul.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "scatterwalk.h"
struct gcm_instance_ctx {
struct crypto_spawn ctr;
};
struct crypto_gcm_ctx {
struct crypto_ablkcipher *ctr;
struct gf128mul_4k *gf128;
};
struct crypto_gcm_ghash_ctx {
u32 bytes;
u32 flags;
struct gf128mul_4k *gf128;
u8 buffer[16];
};
struct crypto_gcm_req_priv_ctx {
u8 auth_tag[16];
u8 counter[16];
struct crypto_gcm_ghash_ctx ghash;
};
static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx *ctx, u32 flags,
struct gf128mul_4k *gf128)
{
ctx->bytes = 0;
ctx->flags = flags;
ctx->gf128 = gf128;
memset(ctx->buffer, 0, 16);
}
static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx *ctx,
const u8 *src, unsigned int srclen)
{
u8 *dst = ctx->buffer;
if (ctx->bytes) {
int n = min(srclen, ctx->bytes);
u8 *pos = dst + (16 - ctx->bytes);
ctx->bytes -= n;
srclen -= n;
while (n--)
*pos++ ^= *src++;
if (!ctx->bytes)
gf128mul_4k_lle((be128 *)dst, ctx->gf128);
}
while (srclen >= 16) {
crypto_xor(dst, src, 16);
gf128mul_4k_lle((be128 *)dst, ctx->gf128);
src += 16;
srclen -= 16;
}
if (srclen) {
ctx->bytes = 16 - srclen;
while (srclen--)
*dst++ ^= *src++;
}
}
static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx *ctx,
struct scatterlist *sg, int len)
{
struct scatter_walk walk;
u8 *src;
int n;
scatterwalk_start(&walk, sg);
while (len) {
n = scatterwalk_clamp(&walk, len);
if (!n) {
scatterwalk_start(&walk, sg_next(walk.sg));
n = scatterwalk_clamp(&walk, len);
}
src = scatterwalk_map(&walk, 0);
crypto_gcm_ghash_update(ctx, src, n);
len -= n;
scatterwalk_unmap(src, 0);
scatterwalk_advance(&walk, n);
scatterwalk_done(&walk, 0, len);
if (len)
crypto_yield(ctx->flags);
}
}
static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx *ctx)
{
u8 *dst = ctx->buffer;
if (ctx->bytes) {
u8 *tmp = dst + (16 - ctx->bytes);
while (ctx->bytes--)
*tmp++ ^= 0;
gf128mul_4k_lle((be128 *)dst, ctx->gf128);
}
ctx->bytes = 0;
}
static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx *ctx,
unsigned int authlen,
unsigned int cryptlen, u8 *dst)
{
u8 *buf = ctx->buffer;
u128 lengths;
lengths.a = cpu_to_be64(authlen * 8);
lengths.b = cpu_to_be64(cryptlen * 8);
crypto_gcm_ghash_flush(ctx);
crypto_xor(buf, (u8 *)&lengths, 16);
gf128mul_4k_lle((be128 *)buf, ctx->gf128);
crypto_xor(dst, buf, 16);
}
static inline void crypto_gcm_set_counter(u8 *counterblock, u32 value)
{
*((u32 *)&counterblock[12]) = cpu_to_be32(value);
}
static int crypto_gcm_encrypt_counter(struct crypto_aead *aead, u8 *block,
u32 value, const u8 *iv)
{
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_ablkcipher *ctr = ctx->ctr;
struct ablkcipher_request req;
struct scatterlist sg;
u8 counterblock[16];
if (iv == NULL)
memset(counterblock, 0, 12);
else
memcpy(counterblock, iv, 12);
crypto_gcm_set_counter(counterblock, value);
sg_init_one(&sg, block, 16);
ablkcipher_request_set_tfm(&req, ctr);
ablkcipher_request_set_crypt(&req, &sg, &sg, 16, counterblock);
ablkcipher_request_set_callback(&req, 0, NULL, NULL);
memset(block, 0, 16);
return crypto_ablkcipher_encrypt(&req);
}
static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
unsigned int keylen)
{
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_ablkcipher *ctr = ctx->ctr;
int alignmask = crypto_ablkcipher_alignmask(ctr);
u8 alignbuf[16+alignmask];
u8 *hash = (u8 *)ALIGN((unsigned long)alignbuf, alignmask+1);
int err = 0;
crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
CRYPTO_TFM_REQ_MASK);
err = crypto_ablkcipher_setkey(ctr, key, keylen);
if (err)
goto out;
crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
CRYPTO_TFM_RES_MASK);
err = crypto_gcm_encrypt_counter(aead, hash, -1, NULL);
if (err)
goto out;
if (ctx->gf128 != NULL)
gf128mul_free_4k(ctx->gf128);
ctx->gf128 = gf128mul_init_4k_lle((be128 *)hash);
if (ctx->gf128 == NULL)
err = -ENOMEM;
out:
return err;
}
static int crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
struct aead_request *req,
void (*done)(struct crypto_async_request *,
int))
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
u32 flags = req->base.tfm->crt_flags;
u8 *auth_tag = pctx->auth_tag;
u8 *counter = pctx->counter;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
int err = 0;
ablkcipher_request_set_tfm(ablk_req, ctx->ctr);
ablkcipher_request_set_callback(ablk_req, aead_request_flags(req),
done, req);
ablkcipher_request_set_crypt(ablk_req, req->src, req->dst,
req->cryptlen, counter);
err = crypto_gcm_encrypt_counter(aead, auth_tag, 0, req->iv);
if (err)
goto out;
memcpy(counter, req->iv, 12);
crypto_gcm_set_counter(counter, 1);
crypto_gcm_ghash_init(ghash, flags, ctx->gf128);
if (req->assoclen) {
crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen);
crypto_gcm_ghash_flush(ghash);
}
out:
return err;
}
static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err)
{
struct aead_request *req = areq->data;
struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
u8 *auth_tag = pctx->auth_tag;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen);
crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
auth_tag);
aead_request_complete(req, err);
}
static int crypto_gcm_encrypt(struct aead_request *req)
{
struct ablkcipher_request abreq;
struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
u8 *auth_tag = pctx->auth_tag;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
int err = 0;
err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_encrypt_done);
if (err)
return err;
if (req->cryptlen) {
err = crypto_ablkcipher_encrypt(&abreq);
if (err)
return err;
crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen);
}
crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
auth_tag);
return err;
}
static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
{
aead_request_complete(areq->data, err);
}
static int crypto_gcm_decrypt(struct aead_request *req)
{
struct ablkcipher_request abreq;
struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
u8 *auth_tag = pctx->auth_tag;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
u8 tag[16];
int err;
if (!req->cryptlen)
return -EINVAL;
memcpy(tag, auth_tag, 16);
err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_decrypt_done);
if (err)
return err;
crypto_gcm_ghash_update_sg(ghash, req->src, req->cryptlen);
crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
auth_tag);
if (memcmp(tag, auth_tag, 16))
return -EINVAL;
return crypto_ablkcipher_decrypt(&abreq);
}
static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct gcm_instance_ctx *ictx = crypto_instance_ctx(inst);
struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
struct crypto_ablkcipher *ctr;
unsigned long align;
int err;
ctr = crypto_spawn_ablkcipher(&ictx->ctr);
err = PTR_ERR(ctr);
if (IS_ERR(ctr))
return err;
ctx->ctr = ctr;
ctx->gf128 = NULL;
align = max_t(unsigned long, crypto_ablkcipher_alignmask(ctr),
__alignof__(u32) - 1);
align &= ~(crypto_tfm_ctx_alignment() - 1);
tfm->crt_aead.reqsize = align + sizeof(struct crypto_gcm_req_priv_ctx);
return 0;
}
static void crypto_gcm_exit_tfm(struct crypto_tfm *tfm)
{
struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
if (ctx->gf128 != NULL)
gf128mul_free_4k(ctx->gf128);
crypto_free_ablkcipher(ctx->ctr);
}
static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
{
struct crypto_instance *inst;
struct crypto_alg *ctr;
struct crypto_alg *cipher;
struct gcm_instance_ctx *ctx;
int err;
char ctr_name[CRYPTO_MAX_ALG_NAME];
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
if (err)
return ERR_PTR(err);
cipher = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
inst = ERR_PTR(PTR_ERR(cipher));
if (IS_ERR(cipher))
return inst;
inst = ERR_PTR(ENAMETOOLONG);
if (snprintf(
ctr_name, CRYPTO_MAX_ALG_NAME,
"ctr(%s,0,16,4)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME)
return inst;
ctr = crypto_alg_mod_lookup(ctr_name, CRYPTO_ALG_TYPE_BLKCIPHER,
CRYPTO_ALG_TYPE_MASK);
if (IS_ERR(ctr))
return ERR_PTR(PTR_ERR(ctr));
if (cipher->cra_blocksize != 16)
goto out_put_ctr;
inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
err = -ENOMEM;
if (!inst)
goto out_put_ctr;
err = -ENAMETOOLONG;
if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
"gcm(%s)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME ||
snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
"gcm(%s)", cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
goto err_free_inst;
ctx = crypto_instance_ctx(inst);
err = crypto_init_spawn(&ctx->ctr, ctr, inst, CRYPTO_ALG_TYPE_MASK);
if (err)
goto err_free_inst;
inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
inst->alg.cra_priority = ctr->cra_priority;
inst->alg.cra_blocksize = 16;
inst->alg.cra_alignmask = __alignof__(u32) - 1;
inst->alg.cra_type = &crypto_aead_type;
inst->alg.cra_aead.ivsize = 12;
inst->alg.cra_aead.maxauthsize = 16;
inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
inst->alg.cra_init = crypto_gcm_init_tfm;
inst->alg.cra_exit = crypto_gcm_exit_tfm;
inst->alg.cra_aead.setkey = crypto_gcm_setkey;
inst->alg.cra_aead.encrypt = crypto_gcm_encrypt;
inst->alg.cra_aead.decrypt = crypto_gcm_decrypt;
out:
crypto_mod_put(ctr);
return inst;
err_free_inst:
kfree(inst);
out_put_ctr:
inst = ERR_PTR(err);
goto out;
}
static void crypto_gcm_free(struct crypto_instance *inst)
{
struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);
crypto_drop_spawn(&ctx->ctr);
kfree(inst);
}
static struct crypto_template crypto_gcm_tmpl = {
.name = "gcm",
.alloc = crypto_gcm_alloc,
.free = crypto_gcm_free,
.module = THIS_MODULE,
};
static int __init crypto_gcm_module_init(void)
{
return crypto_register_template(&crypto_gcm_tmpl);
}
static void __exit crypto_gcm_module_exit(void)
{
crypto_unregister_template(&crypto_gcm_tmpl);
}
module_init(crypto_gcm_module_init);
module_exit(crypto_gcm_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Galois/Counter Mode");
MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");