linux/crypto/gcm.c
Herbert Xu 84c9115230 [CRYPTO] gcm: Add support for async ciphers
This patch adds the necessary changes for GCM to be used with async
ciphers.  This would allow it to be used with hardware devices that
support CTR.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-01-11 08:16:42 +11:00

523 lines
13 KiB
C

/*
* 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 <crypto/scatterwalk.h>
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include "internal.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 iauth_tag[16];
struct scatterlist src[2];
struct scatterlist dst[2];
struct crypto_gcm_ghash_ctx ghash;
struct ablkcipher_request abreq;
};
struct crypto_gcm_setkey_result {
int err;
struct completion completion;
};
static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_reqctx(
struct aead_request *req)
{
unsigned long align = crypto_aead_alignmask(crypto_aead_reqtfm(req));
return (void *)PTR_ALIGN((u8 *)aead_request_ctx(req), align + 1);
}
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;
if (!len)
return;
scatterwalk_start(&walk, sg);
while (len) {
n = scatterwalk_clamp(&walk, len);
if (!n) {
scatterwalk_start(&walk, scatterwalk_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 void crypto_gcm_setkey_done(struct crypto_async_request *req, int err)
{
struct crypto_gcm_setkey_result *result = req->data;
if (err == -EINPROGRESS)
return;
result->err = err;
complete(&result->completion);
}
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;
struct {
be128 hash;
u8 iv[8];
struct crypto_gcm_setkey_result result;
struct scatterlist sg[1];
struct ablkcipher_request req;
} *data;
int err;
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)
return err;
crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
CRYPTO_TFM_RES_MASK);
data = kzalloc(sizeof(*data) + crypto_ablkcipher_reqsize(ctr),
GFP_KERNEL);
if (!data)
return -ENOMEM;
init_completion(&data->result.completion);
sg_init_one(data->sg, &data->hash, sizeof(data->hash));
ablkcipher_request_set_tfm(&data->req, ctr);
ablkcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_gcm_setkey_done,
&data->result);
ablkcipher_request_set_crypt(&data->req, data->sg, data->sg,
sizeof(data->hash), data->iv);
err = crypto_ablkcipher_encrypt(&data->req);
if (err == -EINPROGRESS || err == -EBUSY) {
err = wait_for_completion_interruptible(
&data->result.completion);
if (!err)
err = data->result.err;
}
if (err)
goto out;
if (ctx->gf128 != NULL)
gf128mul_free_4k(ctx->gf128);
ctx->gf128 = gf128mul_init_4k_lle(&data->hash);
if (ctx->gf128 == NULL)
err = -ENOMEM;
out:
kfree(data);
return err;
}
static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
struct aead_request *req,
unsigned int cryptlen)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
u32 flags = req->base.tfm->crt_flags;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
struct scatterlist *dst;
__be32 counter = cpu_to_be32(1);
memset(pctx->auth_tag, 0, sizeof(pctx->auth_tag));
memcpy(req->iv + 12, &counter, 4);
sg_init_table(pctx->src, 2);
sg_set_buf(pctx->src, pctx->auth_tag, sizeof(pctx->auth_tag));
scatterwalk_sg_chain(pctx->src, 2, req->src);
dst = pctx->src;
if (req->src != req->dst) {
sg_init_table(pctx->dst, 2);
sg_set_buf(pctx->dst, pctx->auth_tag, sizeof(pctx->auth_tag));
scatterwalk_sg_chain(pctx->dst, 2, req->dst);
dst = pctx->dst;
}
ablkcipher_request_set_tfm(ablk_req, ctx->ctr);
ablkcipher_request_set_crypt(ablk_req, pctx->src, dst,
cryptlen + sizeof(pctx->auth_tag),
req->iv);
crypto_gcm_ghash_init(ghash, flags, ctx->gf128);
crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen);
crypto_gcm_ghash_flush(ghash);
}
static int crypto_gcm_hash(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(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);
scatterwalk_map_and_copy(auth_tag, req->dst, req->cryptlen,
crypto_aead_authsize(aead), 1);
return 0;
}
static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err)
{
struct aead_request *req = areq->data;
if (!err)
err = crypto_gcm_hash(req);
aead_request_complete(req, err);
}
static int crypto_gcm_encrypt(struct aead_request *req)
{
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct ablkcipher_request *abreq = &pctx->abreq;
int err;
crypto_gcm_init_crypt(abreq, req, req->cryptlen);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
crypto_gcm_encrypt_done, req);
err = crypto_ablkcipher_encrypt(abreq);
if (err)
return err;
return crypto_gcm_hash(req);
}
static int crypto_gcm_verify(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
u8 *auth_tag = pctx->auth_tag;
u8 *iauth_tag = pctx->iauth_tag;
unsigned int authsize = crypto_aead_authsize(aead);
unsigned int cryptlen = req->cryptlen - authsize;
crypto_gcm_ghash_final_xor(ghash, req->assoclen, cryptlen, auth_tag);
authsize = crypto_aead_authsize(aead);
scatterwalk_map_and_copy(iauth_tag, req->src, cryptlen, authsize, 0);
return memcmp(iauth_tag, auth_tag, authsize) ? -EBADMSG : 0;
}
static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
{
struct aead_request *req = areq->data;
if (!err)
err = crypto_gcm_verify(req);
aead_request_complete(req, err);
}
static int crypto_gcm_decrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct ablkcipher_request *abreq = &pctx->abreq;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
unsigned int cryptlen = req->cryptlen;
unsigned int authsize = crypto_aead_authsize(aead);
int err;
if (cryptlen < authsize)
return -EINVAL;
cryptlen -= authsize;
crypto_gcm_init_crypt(abreq, req, cryptlen);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
crypto_gcm_decrypt_done, req);
crypto_gcm_ghash_update_sg(ghash, req->src, cryptlen);
err = crypto_ablkcipher_decrypt(abreq);
if (err)
return err;
return crypto_gcm_verify(req);
}
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 = crypto_tfm_alg_alignmask(tfm);
align &= ~(crypto_tfm_ctx_alignment() - 1);
tfm->crt_aead.reqsize = align +
sizeof(struct crypto_gcm_req_priv_ctx) +
crypto_ablkcipher_reqsize(ctr);
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)",
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 = ctr->cra_alignmask | (__alignof__(u64) - 1);
inst->alg.cra_type = &crypto_aead_type;
inst->alg.cra_aead.ivsize = 16;
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>");