omap-aes-gcm.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Cryptographic API.
 *
 * Support for OMAP AES GCM HW acceleration.
 *
 * Copyright (c) 2016 Texas Instruments Incorporated
 */

#include <crypto/aes.h>
#include <crypto/engine.h>
#include <crypto/gcm.h>
#include <crypto/internal/aead.h>
#include <crypto/scatterwalk.h>
#include <crypto/skcipher.h>
#include <linux/errno.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/omap-dma.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>
#include <linux/string.h>

#include "omap-crypto.h"
#include "omap-aes.h"

static int omap_aes_gcm_handle_queue(struct omap_aes_dev *dd,
				     struct aead_request *req);

static void omap_aes_gcm_finish_req(struct omap_aes_dev *dd, int ret)
{
	struct aead_request *req = dd->aead_req;

	dd->in_sg = NULL;
	dd->out_sg = NULL;

	crypto_finalize_aead_request(dd->engine, req, ret);

	pm_runtime_put_autosuspend(dd->dev);
}

static void omap_aes_gcm_done_task(struct omap_aes_dev *dd)
{
	u8 *tag;
	int alen, clen, i, ret = 0, nsg;
	struct omap_aes_reqctx *rctx;

	alen = ALIGN(dd->assoc_len, AES_BLOCK_SIZE);
	clen = ALIGN(dd->total, AES_BLOCK_SIZE);
	rctx = aead_request_ctx(dd->aead_req);

	nsg = !!(dd->assoc_len && dd->total);

	dma_sync_sg_for_device(dd->dev, dd->out_sg, dd->out_sg_len,
			       DMA_FROM_DEVICE);
	dma_unmap_sg(dd->dev, dd->in_sg, dd->in_sg_len, DMA_TO_DEVICE);
	dma_unmap_sg(dd->dev, dd->out_sg, dd->out_sg_len, DMA_FROM_DEVICE);
	omap_aes_crypt_dma_stop(dd);

	omap_crypto_cleanup(dd->out_sg, dd->orig_out,
			    dd->aead_req->assoclen, dd->total,
			    FLAGS_OUT_DATA_ST_SHIFT, dd->flags);

	if (dd->flags & FLAGS_ENCRYPT)
		scatterwalk_map_and_copy(rctx->auth_tag,
					 dd->aead_req->dst,
					 dd->total + dd->aead_req->assoclen,
					 dd->authsize, 1);

	omap_crypto_cleanup(&dd->in_sgl[0], NULL, 0, alen,
			    FLAGS_ASSOC_DATA_ST_SHIFT, dd->flags);

	omap_crypto_cleanup(&dd->in_sgl[nsg], NULL, 0, clen,
			    FLAGS_IN_DATA_ST_SHIFT, dd->flags);

	if (!(dd->flags & FLAGS_ENCRYPT)) {
		tag = (u8 *)rctx->auth_tag;
		for (i = 0; i < dd->authsize; i++) {
			if (tag[i]) {
				ret = -EBADMSG;
			}
		}
	}

	omap_aes_gcm_finish_req(dd, ret);
}

static int omap_aes_gcm_copy_buffers(struct omap_aes_dev *dd,
				     struct aead_request *req)
{
	int alen, clen, cryptlen, assoclen, ret;
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	unsigned int authlen = crypto_aead_authsize(aead);
	struct scatterlist *tmp, sg_arr[2];
	int nsg;
	u16 flags;

	assoclen = req->assoclen;
	cryptlen = req->cryptlen;

	if (dd->flags & FLAGS_RFC4106_GCM)
		assoclen -= 8;

	if (!(dd->flags & FLAGS_ENCRYPT))
		cryptlen -= authlen;

	alen = ALIGN(assoclen, AES_BLOCK_SIZE);
	clen = ALIGN(cryptlen, AES_BLOCK_SIZE);

	nsg = !!(assoclen && cryptlen);

	omap_aes_clear_copy_flags(dd);

	sg_init_table(dd->in_sgl, nsg + 1);
	if (assoclen) {
		tmp = req->src;
		ret = omap_crypto_align_sg(&tmp, assoclen,
					   AES_BLOCK_SIZE, dd->in_sgl,
					   OMAP_CRYPTO_COPY_DATA |
					   OMAP_CRYPTO_ZERO_BUF |
					   OMAP_CRYPTO_FORCE_SINGLE_ENTRY,
					   FLAGS_ASSOC_DATA_ST_SHIFT,
					   &dd->flags);
		if (ret)
			return ret;
	}

	if (cryptlen) {
		tmp = scatterwalk_ffwd(sg_arr, req->src, req->assoclen);

		if (nsg)
			sg_unmark_end(dd->in_sgl);

		ret = omap_crypto_align_sg(&tmp, cryptlen,
					   AES_BLOCK_SIZE, &dd->in_sgl[nsg],
					   OMAP_CRYPTO_COPY_DATA |
					   OMAP_CRYPTO_ZERO_BUF |
					   OMAP_CRYPTO_FORCE_SINGLE_ENTRY,
					   FLAGS_IN_DATA_ST_SHIFT,
					   &dd->flags);
		if (ret)
			return ret;
	}

	dd->in_sg = dd->in_sgl;
	dd->total = cryptlen;
	dd->assoc_len = assoclen;
	dd->authsize = authlen;

	dd->out_sg = req->dst;
	dd->orig_out = req->dst;

	dd->out_sg = scatterwalk_ffwd(sg_arr, req->dst, req->assoclen);

	flags = 0;
	if (req->src == req->dst || dd->out_sg == sg_arr)
		flags |= OMAP_CRYPTO_FORCE_COPY;

	if (cryptlen) {
		ret = omap_crypto_align_sg(&dd->out_sg, cryptlen,
					   AES_BLOCK_SIZE, &dd->out_sgl,
					   flags,
					   FLAGS_OUT_DATA_ST_SHIFT, &dd->flags);
		if (ret)
			return ret;
	}

	dd->in_sg_len = sg_nents_for_len(dd->in_sg, alen + clen);
	dd->out_sg_len = sg_nents_for_len(dd->out_sg, clen);

	return 0;
}

static int do_encrypt_iv(struct aead_request *req, u32 *tag, u32 *iv)
{
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));

	aes_encrypt(&ctx->actx, (u8 *)tag, (u8 *)iv);
	return 0;
}

void omap_aes_gcm_dma_out_callback(void *data)
{
	struct omap_aes_dev *dd = data;
	struct omap_aes_reqctx *rctx;
	int i, val;
	u32 *auth_tag, tag[4];

	if (!(dd->flags & FLAGS_ENCRYPT))
		scatterwalk_map_and_copy(tag, dd->aead_req->src,
					 dd->total + dd->aead_req->assoclen,
					 dd->authsize, 0);

	rctx = aead_request_ctx(dd->aead_req);
	auth_tag = (u32 *)rctx->auth_tag;
	for (i = 0; i < 4; i++) {
		val = omap_aes_read(dd, AES_REG_TAG_N(dd, i));
		auth_tag[i] = val ^ auth_tag[i];
		if (!(dd->flags & FLAGS_ENCRYPT))
			auth_tag[i] = auth_tag[i] ^ tag[i];
	}

	omap_aes_gcm_done_task(dd);
}

static int omap_aes_gcm_handle_queue(struct omap_aes_dev *dd,
				     struct aead_request *req)
{
	if (req)
		return crypto_transfer_aead_request_to_engine(dd->engine, req);

	return 0;
}

static int omap_aes_gcm_prepare_req(struct aead_request *req,
				    struct omap_aes_dev *dd)
{
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
	int err;

	dd->aead_req = req;

	rctx->mode &= FLAGS_MODE_MASK;
	dd->flags = (dd->flags & ~FLAGS_MODE_MASK) | rctx->mode;

	err = omap_aes_gcm_copy_buffers(dd, req);
	if (err)
		return err;

	dd->ctx = &ctx->octx;

	return omap_aes_write_ctrl(dd);
}

static int omap_aes_gcm_crypt(struct aead_request *req, unsigned long mode)
{
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	unsigned int authlen = crypto_aead_authsize(aead);
	struct omap_aes_dev *dd;
	__be32 counter = cpu_to_be32(1);
	int err, assoclen;

	memset(rctx->auth_tag, 0, sizeof(rctx->auth_tag));
	memcpy(rctx->iv + GCM_AES_IV_SIZE, &counter, 4);

	err = do_encrypt_iv(req, (u32 *)rctx->auth_tag, (u32 *)rctx->iv);
	if (err)
		return err;

	if (mode & FLAGS_RFC4106_GCM)
		assoclen = req->assoclen - 8;
	else
		assoclen = req->assoclen;
	if (assoclen + req->cryptlen == 0) {
		scatterwalk_map_and_copy(rctx->auth_tag, req->dst, 0, authlen,
					 1);
		return 0;
	}

	dd = omap_aes_find_dev(rctx);
	if (!dd)
		return -ENODEV;
	rctx->mode = mode;

	return omap_aes_gcm_handle_queue(dd, req);
}

int omap_aes_gcm_encrypt(struct aead_request *req)
{
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);

	memcpy(rctx->iv, req->iv, GCM_AES_IV_SIZE);
	return omap_aes_gcm_crypt(req, FLAGS_ENCRYPT | FLAGS_GCM);
}

int omap_aes_gcm_decrypt(struct aead_request *req)
{
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);

	memcpy(rctx->iv, req->iv, GCM_AES_IV_SIZE);
	return omap_aes_gcm_crypt(req, FLAGS_GCM);
}

int omap_aes_4106gcm_encrypt(struct aead_request *req)
{
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);

	memcpy(rctx->iv, ctx->octx.nonce, 4);
	memcpy(rctx->iv + 4, req->iv, 8);
	return crypto_ipsec_check_assoclen(req->assoclen) ?:
	       omap_aes_gcm_crypt(req, FLAGS_ENCRYPT | FLAGS_GCM |
				  FLAGS_RFC4106_GCM);
}

int omap_aes_4106gcm_decrypt(struct aead_request *req)
{
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);

	memcpy(rctx->iv, ctx->octx.nonce, 4);
	memcpy(rctx->iv + 4, req->iv, 8);
	return crypto_ipsec_check_assoclen(req->assoclen) ?:
	       omap_aes_gcm_crypt(req, FLAGS_GCM | FLAGS_RFC4106_GCM);
}

int omap_aes_gcm_setkey(struct crypto_aead *tfm, const u8 *key,
			unsigned int keylen)
{
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(tfm);
	int ret;

	ret = aes_expandkey(&ctx->actx, key, keylen);
	if (ret)
		return ret;

	memcpy(ctx->octx.key, key, keylen);
	ctx->octx.keylen = keylen;

	return 0;
}

int omap_aes_4106gcm_setkey(struct crypto_aead *tfm, const u8 *key,
			    unsigned int keylen)
{
	struct omap_aes_gcm_ctx *ctx = crypto_aead_ctx(tfm);
	int ret;

	if (keylen < 4)
		return -EINVAL;
	keylen -= 4;

	ret = aes_expandkey(&ctx->actx, key, keylen);
	if (ret)
		return ret;

	memcpy(ctx->octx.key, key, keylen);
	memcpy(ctx->octx.nonce, key + keylen, 4);
	ctx->octx.keylen = keylen;

	return 0;
}

int omap_aes_gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
	return crypto_gcm_check_authsize(authsize);
}

int omap_aes_4106gcm_setauthsize(struct crypto_aead *parent,
				 unsigned int authsize)
{
	return crypto_rfc4106_check_authsize(authsize);
}

int omap_aes_gcm_crypt_req(struct crypto_engine *engine, void *areq)
{
	struct aead_request *req = container_of(areq, struct aead_request,
						base);
	struct omap_aes_reqctx *rctx = aead_request_ctx(req);
	struct omap_aes_dev *dd = rctx->dd;
	int ret;

	if (!dd)
		return -ENODEV;

	ret = omap_aes_gcm_prepare_req(req, dd);
	if (ret)
		return ret;

	if (dd->in_sg_len)
		ret = omap_aes_crypt_dma_start(dd);
	else
		omap_aes_gcm_dma_out_callback(dd);

	return ret;
}

int omap_aes_gcm_cra_init(struct crypto_aead *tfm)
{
	crypto_aead_set_reqsize(tfm, sizeof(struct omap_aes_reqctx));

	return 0;
}