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// SPDX-License-Identifier: GPL-2.0+
/*
* STM32MP ECDSA verification via the ROM API
*
* Implements ECDSA signature verification via the STM32MP ROM.
*/
#include <asm/system.h>
#include <dm/device.h>
#include <linux/types.h>
#include <u-boot/ecdsa.h>
#include <crypto/ecdsa-uclass.h>
#include <linux/libfdt.h>
#include <dm/platdata.h>
#define ROM_API_SUCCESS 0x77
#define ROM_API_ECDSA_ALGO_PRIME_256V1 1
#define ROM_API_ECDSA_ALGO_BRAINPOOL_256 2
#define ROM_API_OFFSET_ECDSA_VERIFY 0x60
struct ecdsa_rom_api {
uint32_t (*ecdsa_verify_signature)(const void *hash, const void *pubkey,
const void *signature,
uint32_t ecc_algo);
};
/*
* Without forcing the ".data" section, this would get saved in ".bss". BSS
* will be cleared soon after, so it's not suitable.
*/
static uintptr_t rom_api_loc __section(".data");
/*
* The ROM gives us the API location in r0 when starting. This is only available
* during SPL, as there isn't (yet) a mechanism to pass this on to u-boot.
*/
void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
unsigned long r3)
{
rom_api_loc = r0;
save_boot_params_ret();
}
static void stm32mp_rom_get_ecdsa_functions(struct ecdsa_rom_api *rom)
{
uintptr_t verify_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_VERIFY;
rom->ecdsa_verify_signature = *(void **)verify_ptr;
}
static int ecdsa_key_algo(const char *curve_name)
{
if (!strcmp(curve_name, "prime256v1"))
return ROM_API_ECDSA_ALGO_PRIME_256V1;
else if (!strcmp(curve_name, "brainpool256"))
return ROM_API_ECDSA_ALGO_BRAINPOOL_256;
else
return -ENOPROTOOPT;
}
static int romapi_ecdsa_verify(struct udevice *dev,
const struct ecdsa_public_key *pubkey,
const void *hash, size_t hash_len,
const void *signature, size_t sig_len)
{
struct ecdsa_rom_api rom;
uint8_t raw_key[64];
uint32_t rom_ret;
int algo;
/* The ROM API can only handle 256-bit ECDSA keys. */
if (sig_len != 64 || hash_len != 32 || pubkey->size_bits != 256)
return -EINVAL;
algo = ecdsa_key_algo(pubkey->curve_name);
if (algo < 0)
return algo;
/* The ROM API wants the (X, Y) coordinates concatenated. */
memcpy(raw_key, pubkey->x, 32);
memcpy(raw_key + 32, pubkey->y, 32);
stm32mp_rom_get_ecdsa_functions(&rom);
rom_ret = rom.ecdsa_verify_signature(hash, raw_key, signature, algo);
return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
}
static const struct ecdsa_ops rom_api_ops = {
.verify = romapi_ecdsa_verify,
};
U_BOOT_DRIVER(stm32mp_rom_api_ecdsa) = {
.name = "stm32mp_rom_api_ecdsa",
.id = UCLASS_ECDSA,
.ops = &rom_api_ops,
.flags = DM_FLAG_PRE_RELOC,
};
U_BOOT_DRVINFO(stm32mp_rom_api_ecdsa) = {
.name = "stm32mp_rom_api_ecdsa",
};
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