path: root/board/broadcom/bcmbca/board_secure_utils.c

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Copyright 2020 Broadcom Ltd.
 */
#include <common.h>
#include <fdtdec.h>
#include <asm/types.h>
#include <asm/byteorder.h>
#include <linux/errno.h>
#include <asm/unaligned.h>
#include <malloc.h>
#include "tpl_params.h"
#include "spl_env.h"
#include "bcm_secure.h"
#include "u-boot/rsa.h"
#include "u-boot/rsa-mod-exp.h"
#include <u-boot/sha256.h>
#include <uboot_aes.h>
#include <watchdog.h>
#include "mini-gmp/mini-gmp.h"
#include "mini-gmp/mini-mpq.h"

#ifdef BCM_SEC_KEY_OBFUSCATION

static int sec_gen_key(u8* key)
{
	// setup bootlut 
	// A sketch
	int i, rc = -1;
	/* secure mailbox */
	volatile u32 *rng = 0xff800b00;
	/* enable an RNG default was 0x11 <<*/
	rng[(0x80>>2)] = (0x1|(0x11<<13));
	/* if count not 0 and not empty */	
	while((rng[(0xa4>>2)]>>31) > 0 || rng[(0xa4>>2)] < 8 );
	if ((rng[(0xa4>>2)]&0xff)) {
		u32 key[8];	
		/* Collect words*/
		for (i = 0; i < 8; i++ ) {
			key[i] =  rng[(0xa0>>2)];
		}
		rc = 0;
	}
	return rc;
}

int sec_mbox_set(u8* key)
{
	// setup bootlut 
	// A sketch
	int i;
	/* secure mailbox */
	volatile u32 *bootlut = 0xffff0000;
	/* Collect words*/
	for (i = 0; i < 8; i++ ) {
		bootlut[i] =  key[i];
	}
	bootlut[(0x40>>2)] = 0xdd;
}


int sec_mbox_get(u8* key)
{
	// setup bootlut 
	// A sketch
	int i;
	/* secure mailbox */
	volatile u32 *bootlut = 0xffff0000;
	/* Collect words*/
	for (i = 0; i < 8; i++ ) {
		key[i] = bootlut[i];
	}
}
u8* obfuscate(const u8* s,
	u32 len)
{
	u8 ses_key[AES128_KEY_LENGTH*2];
	/*Get aes */
	/* After this line only secure master could write to the mailbox register*/
	u8* dat = malloc(len);
	if (dat && !sec_gen_key(ses_key)) {
		memcpy(dat, s, len);
		bcm_sec_aes_cbc128(ses_key, ses_key+AES128_KEY_LENGTH, dat, len, 1);
		sec_set_mbox(ses_key);		
		return dat;
	} 
	if (dat) {
		free(dat);
	} 
	return NULL; 
}

u8* deobfuscate(u8* s,
	u32 len)
{
	u8 ses_key[AES128_KEY_LENGTH*2];
	/*Get aes */
	/* After this line only secure master could write to the mailbox register*/
	sec_get_mbox(ses_key);
	bcm_sec_aes_cbc128(ses_key, ses_key+AES128_KEY_LENGTH, s, len, 0);
	return s;
}
#endif


#if defined (CONFIG_TPL_BUILD)
extern tpl_params * tplparams;

static inline char* __get_ev(const char* nm)
{
        char* k = NULL;
        if (!tplparams) {
                return NULL;
        }
        k = find_spl_env_val(tplparams->environment, nm);
        if (!k) {
                return NULL;
        }
        return k;
}

#else

static inline char* __get_ev(const char* nm)
{
        return env_get(nm);
}

#endif
int bcm_util_hex2u32(const char* s, u8*  d)
{
	int len;
	u32* u = (u32*)d ;
        char buf[sizeof(u32)*2 + sizeof(u8)] = {0};
	char* pmax, *p = (char*)s;
	if (!p || !d) {
		return -1;
	}

	len = strlen(p);
	len -= (len%sizeof(u32));
	pmax = (char*)s + len; 
        while(p < pmax )        {
                memcpy(buf, p, sizeof(u32)*2);
                *u++ = ntohl(simple_strtoul((const char*)buf, NULL, 16));
                //printf("\n %x %s \n",new_key[j-1],buf);
                p += sizeof(u32)*2;
        }
	return len/2; 
}

u8* bcm_util_env_var2bin(const char* id, u32 len )
{
        char* p = NULL, *pmax;
        u8 *data = NULL;
        char buf[sizeof(u32)*2+sizeof(u8)] = {0};
        int j = 0 ;
        p = __get_ev(id);
        if (!p) {
                debug("No key\n");
                return NULL;
        }
        pmax = p + strlen((const char*)p);
        if (pmax-p != len*2) {
                printf("ERROR: invalid length for %s;must be %d got only %d\n",
                id, len*2, (u32)(pmax - p));
                return NULL;
        }
        data = malloc(len);
        if (!data) {
                return NULL;
        }
        while(p < pmax )        {
                memcpy(buf, p, sizeof(u32)*2);
                ((u32*)data)[j++] = ntohl(simple_strtoul((const char*)buf, NULL, 16));
                //printf("\n %x %s \n",new_key[j-1],buf);
                p += sizeof(u32)*2;
        }
        return data;
}

void bcm_sec_aes_cbc128(u8 *key, u8 *iv, u8* txt, 
			u32 length, u32 flag)
{ 
	u32 num_aes_blocks;
	u8 key_schedule[AES128_EXPAND_KEY_LENGTH];
	aes_expand_key(key, AES128_KEY_LENGTH, key_schedule);
	num_aes_blocks = (length + AES128_KEY_LENGTH - 1) / AES128_KEY_LENGTH;
	flag? aes_cbc_encrypt_blocks(AES128_KEY_LENGTH, key_schedule, iv, txt, txt, num_aes_blocks) :
			aes_cbc_decrypt_blocks(AES128_KEY_LENGTH, key_schedule, iv, txt, txt, num_aes_blocks);
}

static inline void checksum_sha256(const u8 *obj, 
				u32 len, u8* hash)
{
	sha256_context ctx;
	sha256_starts(&ctx);
	sha256_update(&ctx, obj, len);
	sha256_finish(&ctx, hash);
}

static int rsa_get_params(const u8* modulus,
			u32 modulus_size,	
			unsigned long *n0inv, 
			u8 *rr)
{
	size_t wcnt; 
	int rc = 0; 
	mpz_t	 _inv, _n0inv, 
		_r_sqrd, _key, _2_32, _2, _2_x;

	mpz_init (_n0inv);
	mpz_init (_inv);
	mpz_init (_r_sqrd);
	mpz_init (_key);
	mpz_init (_2);
	mpz_init (_2_32);
	mpz_init (_2_x);
	mpz_set_ui (_2, 2);
	mpz_import(_key , modulus_size, 1, sizeof(u8), 0, 0, modulus);
	mpz_pow_ui(_2_32, _2, 32);
	/* Calculate an inverse for _key and 2^32 */
	if ( mpz_invert(_inv, _key, _2_32) == 0) {
		rc = -1;
		goto err;
	}
	/*subtract to get negative of _inv*/
	mpz_sub(_n0inv, _2_32, _inv);
	
	mpz_export(n0inv, &wcnt, 1, sizeof(unsigned long), -1, 0, _n0inv);
	
	/*printf(" wcnt;--- n0inv:  %lu \n \t 0x%u\n", wcnt, *n0inv);*/
	/* RSA2048_BYTES converted to bits then multipled by 2 
  		to square [2^(RSA2048_BYTES*8)]^2
	*/
	mpz_pow_ui(_2_x, _2, modulus_size*8*2);
	/* modulo division to get an r-squared */
	mpz_mod(_r_sqrd, _2_x, _key);

	mpz_export(rr, &wcnt, 1, modulus_size, 1, 0, _r_sqrd);
	//dbg_hex(rr, RSA2048_BYTES, "R squared:");
err:
	mpz_clear (_n0inv);
	mpz_clear (_inv);
	mpz_clear (_r_sqrd);
	mpz_clear (_key);
	mpz_clear (_2);
	mpz_clear (_2_32);
	mpz_clear (_2_x);
	return rc;

}


void bcm_sec_digest(const u8 *data, u32 len, u8* digest, char* algo)
{
	//TODO: Support other algo, currently Ignoring algo and defaulting to sha256
	checksum_sha256(data, len, digest);
}

int bcm_sec_rsa_verify(const u8 *obj, 
		u32 obj_len, const u8* sig, 
		u32 sig_len, const u8 *pub, 
		struct image_sign_info *im )
{
	int rc = -1;
	struct key_prop rsa_prop ;
	u8 hash[SHA256_SUM_LEN] = {0};
	u8 rr[RSA2048_BYTES*2] = {0};
        u8	sig_dec[RSA2048_BYTES] = {0};
	unsigned long n0inv = 0;
	checksum_sha256(obj, obj_len, hash);
	rc = rsa_get_params(pub, RSA2048_BYTES, &n0inv, rr); 
	if (rc) {
		printf("ERROR: rsa arguments\n");	
		goto err;
	}

	rsa_prop.modulus = pub;
	rsa_prop.n0inv = n0inv;
	rsa_prop.rr = rr;
	rsa_prop.num_bits = RSA2048_BYTES*8;
	rsa_prop.exp_len = 4;
	rsa_prop.public_exponent = NULL;
	rc = rsa_mod_exp_sw(sig, sig_len, &rsa_prop, sig_dec);
	if (rc) {
		printf("ERROR: rsa decryption\n");	
		goto err; 
	}
	//dbg_hex(sig_dec, RSA2048_BYTES, " Sig Decrypted :");
	//dbg_hex(hash, SHA256_SUM_LEN, " hash :");
	rc = padding_pss_verify(im, sig_dec, RSA2048_BYTES, hash, SHA256_SUM_LEN);
err:
	memset(sig_dec, 0, RSA2048_BYTES);
	memset(hash, 0, SHA256_SUM_LEN);
	memset(rr, 0, RSA2048_BYTES*2);
	memset(&rsa_prop, 0, sizeof(struct key_prop));
	return rc;
}