linux/crypto/gcm.c

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/*
* 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>");