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The STM32MP ROM provides several service. One of them is the ability to verify ecdsa256 signatures. Hook the ROM API into the ECDSA uclass. Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com> Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
103 lines
2.7 KiB
C
103 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* STM32MP ECDSA verification via the ROM API
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*
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* Implements ECDSA signature verification via the STM32MP ROM.
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*/
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#include <asm/system.h>
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#include <dm/device.h>
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#include <linux/types.h>
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#include <u-boot/ecdsa.h>
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#include <crypto/ecdsa-uclass.h>
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#include <linux/libfdt.h>
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#include <dm/platdata.h>
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#define ROM_API_SUCCESS 0x77
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#define ROM_API_ECDSA_ALGO_PRIME_256V1 1
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#define ROM_API_ECDSA_ALGO_BRAINPOOL_256 2
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#define ROM_API_OFFSET_ECDSA_VERIFY 0x60
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struct ecdsa_rom_api {
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uint32_t (*ecdsa_verify_signature)(const void *hash, const void *pubkey,
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const void *signature,
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uint32_t ecc_algo);
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};
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/*
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* Without forcing the ".data" section, this would get saved in ".bss". BSS
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* will be cleared soon after, so it's not suitable.
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*/
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static uintptr_t rom_api_loc __section(".data");
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/*
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* The ROM gives us the API location in r0 when starting. This is only available
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* during SPL, as there isn't (yet) a mechanism to pass this on to u-boot.
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*/
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void save_boot_params(unsigned long r0, unsigned long r1, unsigned long r2,
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unsigned long r3)
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{
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rom_api_loc = r0;
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save_boot_params_ret();
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}
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static void stm32mp_rom_get_ecdsa_functions(struct ecdsa_rom_api *rom)
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{
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uintptr_t verify_ptr = rom_api_loc + ROM_API_OFFSET_ECDSA_VERIFY;
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rom->ecdsa_verify_signature = *(void **)verify_ptr;
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}
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static int ecdsa_key_algo(const char *curve_name)
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{
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if (!strcmp(curve_name, "prime256v1"))
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return ROM_API_ECDSA_ALGO_PRIME_256V1;
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else if (!strcmp(curve_name, "brainpool256"))
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return ROM_API_ECDSA_ALGO_BRAINPOOL_256;
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else
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return -ENOPROTOOPT;
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}
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static int romapi_ecdsa_verify(struct udevice *dev,
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const struct ecdsa_public_key *pubkey,
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const void *hash, size_t hash_len,
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const void *signature, size_t sig_len)
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{
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struct ecdsa_rom_api rom;
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uint8_t raw_key[64];
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uint32_t rom_ret;
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int algo;
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/* The ROM API can only handle 256-bit ECDSA keys. */
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if (sig_len != 64 || hash_len != 32 || pubkey->size_bits != 256)
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return -EINVAL;
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algo = ecdsa_key_algo(pubkey->curve_name);
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if (algo < 0)
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return algo;
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/* The ROM API wants the (X, Y) coordinates concatenated. */
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memcpy(raw_key, pubkey->x, 32);
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memcpy(raw_key + 32, pubkey->y, 32);
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stm32mp_rom_get_ecdsa_functions(&rom);
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rom_ret = rom.ecdsa_verify_signature(hash, raw_key, signature, algo);
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return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
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}
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static const struct ecdsa_ops rom_api_ops = {
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.verify = romapi_ecdsa_verify,
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};
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U_BOOT_DRIVER(stm32mp_rom_api_ecdsa) = {
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.name = "stm32mp_rom_api_ecdsa",
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.id = UCLASS_ECDSA,
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.ops = &rom_api_ops,
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.flags = DM_FLAG_PRE_RELOC,
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};
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U_BOOT_DRVINFO(stm32mp_rom_api_ecdsa) = {
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.name = "stm32mp_rom_api_ecdsa",
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};
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