xref: /openbmc/linux/drivers/crypto/starfive/jh7110-rsa.c (revision 445a4aaf)

// SPDX-License-Identifier: GPL-2.0
/*
 * StarFive Public Key Algo acceleration driver
 *
 * Copyright (c) 2022 StarFive Technology
 */

#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-direct.h>
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <crypto/akcipher.h>
#include <crypto/algapi.h>
#include <crypto/internal/akcipher.h>
#include <crypto/internal/rsa.h>
#include <crypto/scatterwalk.h>

#include "jh7110-cryp.h"

#define STARFIVE_PKA_REGS_OFFSET	0x400
#define STARFIVE_PKA_CACR_OFFSET	(STARFIVE_PKA_REGS_OFFSET + 0x0)
#define STARFIVE_PKA_CASR_OFFSET	(STARFIVE_PKA_REGS_OFFSET + 0x4)
#define STARFIVE_PKA_CAAR_OFFSET	(STARFIVE_PKA_REGS_OFFSET + 0x8)
#define STARFIVE_PKA_CAER_OFFSET	(STARFIVE_PKA_REGS_OFFSET + 0x108)
#define STARFIVE_PKA_CANR_OFFSET	(STARFIVE_PKA_REGS_OFFSET + 0x208)

// R^2 mod N and N0'
#define CRYPTO_CMD_PRE			0x0
// A * R mod N   ==> A
#define CRYPTO_CMD_ARN			0x5
// A * E * R mod N ==> A
#define CRYPTO_CMD_AERN			0x6
// A * A * R mod N ==> A
#define CRYPTO_CMD_AARN			0x7

#define STARFIVE_RSA_MAX_KEYSZ		256
#define STARFIVE_RSA_RESET		0x2

static inline int starfive_pka_wait_done(struct starfive_cryp_ctx *ctx)
{
	struct starfive_cryp_dev *cryp = ctx->cryp;

	return wait_for_completion_timeout(&cryp->pka_done,
					   usecs_to_jiffies(100000));
}

static inline void starfive_pka_irq_mask_clear(struct starfive_cryp_ctx *ctx)
{
	struct starfive_cryp_dev *cryp = ctx->cryp;
	u32 stat;

	stat = readl(cryp->base + STARFIVE_IE_MASK_OFFSET);
	stat &= ~STARFIVE_IE_MASK_PKA_DONE;
	writel(stat, cryp->base + STARFIVE_IE_MASK_OFFSET);

	reinit_completion(&cryp->pka_done);
}

static void starfive_rsa_free_key(struct starfive_rsa_key *key)
{
	if (key->d)
		kfree_sensitive(key->d);
	if (key->e)
		kfree_sensitive(key->e);
	if (key->n)
		kfree_sensitive(key->n);
	memset(key, 0, sizeof(*key));
}

static unsigned int starfive_rsa_get_nbit(u8 *pa, u32 snum, int key_sz)
{
	u32 i;
	u8 value;

	i = snum >> 3;

	value = pa[key_sz - i - 1];
	value >>= snum & 0x7;
	value &= 0x1;

	return value;
}

static int starfive_rsa_montgomery_form(struct starfive_cryp_ctx *ctx,
					u32 *out, u32 *in, u8 mont,
					u32 *mod, int bit_len)
{
	struct starfive_cryp_dev *cryp = ctx->cryp;
	struct starfive_cryp_request_ctx *rctx = ctx->rctx;
	int count = rctx->total / sizeof(u32) - 1;
	int loop;
	u32 temp;
	u8 opsize;

	opsize = (bit_len - 1) >> 5;
	rctx->csr.pka.v = 0;

	writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

	for (loop = 0; loop <= opsize; loop++)
		writel(mod[opsize - loop], cryp->base + STARFIVE_PKA_CANR_OFFSET + loop * 4);

	if (mont) {
		rctx->csr.pka.v = 0;
		rctx->csr.pka.cln_done = 1;
		rctx->csr.pka.opsize = opsize;
		rctx->csr.pka.exposize = opsize;
		rctx->csr.pka.cmd = CRYPTO_CMD_PRE;
		rctx->csr.pka.start = 1;
		rctx->csr.pka.not_r2 = 1;
		rctx->csr.pka.ie = 1;

		starfive_pka_irq_mask_clear(ctx);
		writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

		if (!starfive_pka_wait_done(ctx))
			return -ETIMEDOUT;

		for (loop = 0; loop <= opsize; loop++)
			writel(in[opsize - loop], cryp->base + STARFIVE_PKA_CAAR_OFFSET + loop * 4);

		writel(0x1000000, cryp->base + STARFIVE_PKA_CAER_OFFSET);

		for (loop = 1; loop <= opsize; loop++)
			writel(0, cryp->base + STARFIVE_PKA_CAER_OFFSET + loop * 4);

		rctx->csr.pka.v = 0;
		rctx->csr.pka.cln_done = 1;
		rctx->csr.pka.opsize = opsize;
		rctx->csr.pka.exposize = opsize;
		rctx->csr.pka.cmd = CRYPTO_CMD_AERN;
		rctx->csr.pka.start = 1;
		rctx->csr.pka.ie = 1;

		starfive_pka_irq_mask_clear(ctx);
		writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

		if (!starfive_pka_wait_done(ctx))
			return -ETIMEDOUT;
	} else {
		rctx->csr.pka.v = 0;
		rctx->csr.pka.cln_done = 1;
		rctx->csr.pka.opsize = opsize;
		rctx->csr.pka.exposize = opsize;
		rctx->csr.pka.cmd = CRYPTO_CMD_PRE;
		rctx->csr.pka.start = 1;
		rctx->csr.pka.pre_expf = 1;
		rctx->csr.pka.ie = 1;

		starfive_pka_irq_mask_clear(ctx);
		writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

		if (!starfive_pka_wait_done(ctx))
			return -ETIMEDOUT;

		for (loop = 0; loop <= count; loop++)
			writel(in[count - loop], cryp->base + STARFIVE_PKA_CAER_OFFSET + loop * 4);

		/*pad with 0 up to opsize*/
		for (loop = count + 1; loop <= opsize; loop++)
			writel(0, cryp->base + STARFIVE_PKA_CAER_OFFSET + loop * 4);

		rctx->csr.pka.v = 0;
		rctx->csr.pka.cln_done = 1;
		rctx->csr.pka.opsize = opsize;
		rctx->csr.pka.exposize = opsize;
		rctx->csr.pka.cmd = CRYPTO_CMD_ARN;
		rctx->csr.pka.start = 1;
		rctx->csr.pka.ie = 1;

		starfive_pka_irq_mask_clear(ctx);
		writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

		if (!starfive_pka_wait_done(ctx))
			return -ETIMEDOUT;
	}

	for (loop = 0; loop <= opsize; loop++) {
		temp = readl(cryp->base + STARFIVE_PKA_CAAR_OFFSET + 0x4 * loop);
		out[opsize - loop] = temp;
	}

	return 0;
}

static int starfive_rsa_cpu_start(struct starfive_cryp_ctx *ctx, u32 *result,
				  u8 *de, u32 *n, int key_sz)
{
	struct starfive_cryp_dev *cryp = ctx->cryp;
	struct starfive_cryp_request_ctx *rctx = ctx->rctx;
	struct starfive_rsa_key *key = &ctx->rsa_key;
	u32 temp;
	int ret = 0;
	int opsize, mlen, loop;
	unsigned int *mta;

	opsize = (key_sz - 1) >> 2;

	mta = kmalloc(key_sz, GFP_KERNEL);
	if (!mta)
		return -ENOMEM;

	ret = starfive_rsa_montgomery_form(ctx, mta, (u32 *)rctx->rsa_data,
					   0, n, key_sz << 3);
	if (ret) {
		dev_err_probe(cryp->dev, ret, "Conversion to Montgomery failed");
		goto rsa_err;
	}

	for (loop = 0; loop <= opsize; loop++)
		writel(mta[opsize - loop],
		       cryp->base + STARFIVE_PKA_CAER_OFFSET + loop * 4);

	for (loop = key->bitlen - 1; loop > 0; loop--) {
		mlen = starfive_rsa_get_nbit(de, loop - 1, key_sz);

		rctx->csr.pka.v = 0;
		rctx->csr.pka.cln_done = 1;
		rctx->csr.pka.opsize = opsize;
		rctx->csr.pka.exposize = opsize;
		rctx->csr.pka.cmd = CRYPTO_CMD_AARN;
		rctx->csr.pka.start = 1;
		rctx->csr.pka.ie = 1;

		starfive_pka_irq_mask_clear(ctx);
		writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

		ret = -ETIMEDOUT;
		if (!starfive_pka_wait_done(ctx))
			goto rsa_err;

		if (mlen) {
			rctx->csr.pka.v = 0;
			rctx->csr.pka.cln_done = 1;
			rctx->csr.pka.opsize = opsize;
			rctx->csr.pka.exposize = opsize;
			rctx->csr.pka.cmd = CRYPTO_CMD_AERN;
			rctx->csr.pka.start = 1;
			rctx->csr.pka.ie = 1;

			starfive_pka_irq_mask_clear(ctx);
			writel(rctx->csr.pka.v, cryp->base + STARFIVE_PKA_CACR_OFFSET);

			if (!starfive_pka_wait_done(ctx))
				goto rsa_err;
		}
	}

	for (loop = 0; loop <= opsize; loop++) {
		temp = readl(cryp->base + STARFIVE_PKA_CAAR_OFFSET + 0x4 * loop);
		result[opsize - loop] = temp;
	}

	ret = starfive_rsa_montgomery_form(ctx, result, result, 1, n, key_sz << 3);
	if (ret)
		dev_err_probe(cryp->dev, ret, "Conversion from Montgomery failed");
rsa_err:
	kfree(mta);
	return ret;
}

static int starfive_rsa_start(struct starfive_cryp_ctx *ctx, u8 *result,
			      u8 *de, u8 *n, int key_sz)
{
	return starfive_rsa_cpu_start(ctx, (u32 *)result, de, (u32 *)n, key_sz);
}

static int starfive_rsa_enc_core(struct starfive_cryp_ctx *ctx, int enc)
{
	struct starfive_cryp_dev *cryp = ctx->cryp;
	struct starfive_cryp_request_ctx *rctx = ctx->rctx;
	struct starfive_rsa_key *key = &ctx->rsa_key;
	int ret = 0;

	writel(STARFIVE_RSA_RESET, cryp->base + STARFIVE_PKA_CACR_OFFSET);

	rctx->total = sg_copy_to_buffer(rctx->in_sg, rctx->nents,
					rctx->rsa_data, rctx->total);

	if (enc) {
		key->bitlen = key->e_bitlen;
		ret = starfive_rsa_start(ctx, rctx->rsa_data, key->e,
					 key->n, key->key_sz);
	} else {
		key->bitlen = key->d_bitlen;
		ret = starfive_rsa_start(ctx, rctx->rsa_data, key->d,
					 key->n, key->key_sz);
	}

	if (ret)
		goto err_rsa_crypt;

	sg_copy_buffer(rctx->out_sg, sg_nents(rctx->out_sg),
		       rctx->rsa_data, key->key_sz, 0, 0);

err_rsa_crypt:
	writel(STARFIVE_RSA_RESET, cryp->base + STARFIVE_PKA_CACR_OFFSET);
	kfree(rctx->rsa_data);
	return ret;
}

static int starfive_rsa_enc(struct akcipher_request *req)
{
	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct starfive_cryp_dev *cryp = ctx->cryp;
	struct starfive_rsa_key *key = &ctx->rsa_key;
	struct starfive_cryp_request_ctx *rctx = akcipher_request_ctx(req);
	int ret;

	if (!key->key_sz) {
		akcipher_request_set_tfm(req, ctx->akcipher_fbk);
		ret = crypto_akcipher_encrypt(req);
		akcipher_request_set_tfm(req, tfm);
		return ret;
	}

	if (unlikely(!key->n || !key->e))
		return -EINVAL;

	if (req->dst_len < key->key_sz)
		return dev_err_probe(cryp->dev, -EOVERFLOW,
				     "Output buffer length less than parameter n\n");

	rctx->in_sg = req->src;
	rctx->out_sg = req->dst;
	rctx->total = req->src_len;
	rctx->nents = sg_nents(rctx->in_sg);
	ctx->rctx = rctx;

	return starfive_rsa_enc_core(ctx, 1);
}

static int starfive_rsa_dec(struct akcipher_request *req)
{
	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct starfive_cryp_dev *cryp = ctx->cryp;
	struct starfive_rsa_key *key = &ctx->rsa_key;
	struct starfive_cryp_request_ctx *rctx = akcipher_request_ctx(req);
	int ret;

	if (!key->key_sz) {
		akcipher_request_set_tfm(req, ctx->akcipher_fbk);
		ret = crypto_akcipher_decrypt(req);
		akcipher_request_set_tfm(req, tfm);
		return ret;
	}

	if (unlikely(!key->n || !key->d))
		return -EINVAL;

	if (req->dst_len < key->key_sz)
		return dev_err_probe(cryp->dev, -EOVERFLOW,
				     "Output buffer length less than parameter n\n");

	rctx->in_sg = req->src;
	rctx->out_sg = req->dst;
	ctx->rctx = rctx;
	rctx->total = req->src_len;

	return starfive_rsa_enc_core(ctx, 0);
}

static int starfive_rsa_set_n(struct starfive_rsa_key *rsa_key,
			      const char *value, size_t vlen)
{
	const char *ptr = value;
	unsigned int bitslen;
	int ret;

	while (!*ptr && vlen) {
		ptr++;
		vlen--;
	}
	rsa_key->key_sz = vlen;
	bitslen = rsa_key->key_sz << 3;

	/* check valid key size */
	if (bitslen & 0x1f)
		return -EINVAL;

	ret = -ENOMEM;
	rsa_key->n = kmemdup(ptr, rsa_key->key_sz, GFP_KERNEL);
	if (!rsa_key->n)
		goto err;

	return 0;
 err:
	rsa_key->key_sz = 0;
	rsa_key->n = NULL;
	starfive_rsa_free_key(rsa_key);
	return ret;
}

static int starfive_rsa_set_e(struct starfive_rsa_key *rsa_key,
			      const char *value, size_t vlen)
{
	const char *ptr = value;
	unsigned char pt;
	int loop;

	while (!*ptr && vlen) {
		ptr++;
		vlen--;
	}
	pt = *ptr;

	if (!rsa_key->key_sz || !vlen || vlen > rsa_key->key_sz) {
		rsa_key->e = NULL;
		return -EINVAL;
	}

	rsa_key->e = kzalloc(rsa_key->key_sz, GFP_KERNEL);
	if (!rsa_key->e)
		return -ENOMEM;

	for (loop = 8; loop > 0; loop--) {
		if (pt >> (loop - 1))
			break;
	}

	rsa_key->e_bitlen = (vlen - 1) * 8 + loop;

	memcpy(rsa_key->e + (rsa_key->key_sz - vlen), ptr, vlen);

	return 0;
}

static int starfive_rsa_set_d(struct starfive_rsa_key *rsa_key,
			      const char *value, size_t vlen)
{
	const char *ptr = value;
	unsigned char pt;
	int loop;
	int ret;

	while (!*ptr && vlen) {
		ptr++;
		vlen--;
	}
	pt = *ptr;

	ret = -EINVAL;
	if (!rsa_key->key_sz || !vlen || vlen > rsa_key->key_sz)
		goto err;

	ret = -ENOMEM;
	rsa_key->d = kzalloc(rsa_key->key_sz, GFP_KERNEL);
	if (!rsa_key->d)
		goto err;

	for (loop = 8; loop > 0; loop--) {
		if (pt >> (loop - 1))
			break;
	}

	rsa_key->d_bitlen = (vlen - 1) * 8 + loop;

	memcpy(rsa_key->d + (rsa_key->key_sz - vlen), ptr, vlen);

	return 0;
 err:
	rsa_key->d = NULL;
	return ret;
}

static int starfive_rsa_setkey(struct crypto_akcipher *tfm, const void *key,
			       unsigned int keylen, bool private)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct rsa_key raw_key = {NULL};
	struct starfive_rsa_key *rsa_key = &ctx->rsa_key;
	int ret;

	if (private)
		ret = rsa_parse_priv_key(&raw_key, key, keylen);
	else
		ret = rsa_parse_pub_key(&raw_key, key, keylen);
	if (ret < 0)
		goto err;

	starfive_rsa_free_key(rsa_key);

	/* Use fallback for mod > 256 + 1 byte prefix */
	if (raw_key.n_sz > STARFIVE_RSA_MAX_KEYSZ + 1)
		return 0;

	ret = starfive_rsa_set_n(rsa_key, raw_key.n, raw_key.n_sz);
	if (ret)
		return ret;

	ret = starfive_rsa_set_e(rsa_key, raw_key.e, raw_key.e_sz);
	if (ret)
		goto err;

	if (private) {
		ret = starfive_rsa_set_d(rsa_key, raw_key.d, raw_key.d_sz);
		if (ret)
			goto err;
	}

	if (!rsa_key->n || !rsa_key->e) {
		ret = -EINVAL;
		goto err;
	}

	if (private && !rsa_key->d) {
		ret = -EINVAL;
		goto err;
	}

	return 0;
 err:
	starfive_rsa_free_key(rsa_key);
	return ret;
}

static int starfive_rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
				    unsigned int keylen)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	int ret;

	ret = crypto_akcipher_set_pub_key(ctx->akcipher_fbk, key, keylen);
	if (ret)
		return ret;

	return starfive_rsa_setkey(tfm, key, keylen, false);
}

static int starfive_rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
				     unsigned int keylen)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	int ret;

	ret = crypto_akcipher_set_priv_key(ctx->akcipher_fbk, key, keylen);
	if (ret)
		return ret;

	return starfive_rsa_setkey(tfm, key, keylen, true);
}

static unsigned int starfive_rsa_max_size(struct crypto_akcipher *tfm)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);

	if (ctx->rsa_key.key_sz)
		return ctx->rsa_key.key_sz;

	return crypto_akcipher_maxsize(ctx->akcipher_fbk);
}

static int starfive_rsa_init_tfm(struct crypto_akcipher *tfm)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);

	ctx->akcipher_fbk = crypto_alloc_akcipher("rsa-generic", 0, 0);
	if (IS_ERR(ctx->akcipher_fbk))
		return PTR_ERR(ctx->akcipher_fbk);

	ctx->cryp = starfive_cryp_find_dev(ctx);
	if (!ctx->cryp) {
		crypto_free_akcipher(ctx->akcipher_fbk);
		return -ENODEV;
	}

	akcipher_set_reqsize(tfm, sizeof(struct starfive_cryp_request_ctx) +
			     sizeof(struct crypto_akcipher) + 32);

	return 0;
}

static void starfive_rsa_exit_tfm(struct crypto_akcipher *tfm)
{
	struct starfive_cryp_ctx *ctx = akcipher_tfm_ctx(tfm);
	struct starfive_rsa_key *key = (struct starfive_rsa_key *)&ctx->rsa_key;

	crypto_free_akcipher(ctx->akcipher_fbk);
	starfive_rsa_free_key(key);
}

static struct akcipher_alg starfive_rsa = {
	.encrypt = starfive_rsa_enc,
	.decrypt = starfive_rsa_dec,
	.sign = starfive_rsa_dec,
	.verify = starfive_rsa_enc,
	.set_pub_key = starfive_rsa_set_pub_key,
	.set_priv_key = starfive_rsa_set_priv_key,
	.max_size = starfive_rsa_max_size,
	.init = starfive_rsa_init_tfm,
	.exit = starfive_rsa_exit_tfm,
	.base = {
		.cra_name = "rsa",
		.cra_driver_name = "starfive-rsa",
		.cra_flags = CRYPTO_ALG_TYPE_AKCIPHER |
			     CRYPTO_ALG_NEED_FALLBACK,
		.cra_priority = 3000,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct starfive_cryp_ctx),
	},
};

int starfive_rsa_register_algs(void)
{
	return crypto_register_akcipher(&starfive_rsa);
}

void starfive_rsa_unregister_algs(void)
{
	crypto_unregister_akcipher(&starfive_rsa);
}