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@@ -0,0 +1,102 @@
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+// 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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+
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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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+
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+#define ROM_API_OFFSET_ECDSA_VERIFY 0x60
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+
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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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+/*
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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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+/*
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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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+
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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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+
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+ rom->ecdsa_verify_signature = *(void **)verify_ptr;
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+}
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ return rom_ret == ROM_API_SUCCESS ? 0 : -EPERM;
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+}
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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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+
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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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+
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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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