[PATCH] imx: ele_ahab: Add HUK derivation support

[Mathieu Othacehe]

Add a new ahab_derive command that derives the hardware unique key (HUK)
into a 16 or 32 bytes key and stores it at the given address.

Signed-off-by: Mathieu Othacehe <othacehe at gnu.org>
---
 arch/arm/include/asm/mach-imx/ele_api.h |  2 +
 arch/arm/mach-imx/ele_ahab.c            | 31 +++++++++++
 drivers/misc/imx_ele/ele_api.c          | 73 +++++++++++++++++++++++++
 3 files changed, 106 insertions(+)

diff --git a/arch/arm/include/asm/mach-imx/ele_api.h b/arch/arm/include/asm/mach-imx/ele_api.h
index a29b849d903..490292ab023 100644
--- a/arch/arm/include/asm/mach-imx/ele_api.h
+++ b/arch/arm/include/asm/mach-imx/ele_api.h
@@ -26,6 +26,7 @@
 #define ELE_GET_EVENTS_REQ (0xA2)
 #define ELE_COMMIT_REQ (0xA8)
 #define ELE_START_RNG (0xA3)
+#define ELE_CMD_DERIVE_KEY (0xA9)
 #define ELE_GENERATE_DEK_BLOB (0xAF)
 #define ELE_ENABLE_PATCH_REQ (0xC3)
 #define ELE_RELEASE_RDC_REQ (0xC4)
@@ -143,6 +144,7 @@ int ele_read_common_fuse(u16 fuse_id, u32 *fuse_words, u32 fuse_num, u32 *respon
 int ele_release_caam(u32 core_did, u32 *response);
 int ele_get_fw_version(u32 *fw_version, u32 *sha1, u32 *response);
 int ele_get_events(u32 *events, u32 *events_cnt, u32 *response);
+int ele_derive_huk(u8 *key, size_t key_size, u8 *ctx);
 int ele_commit(u16 fuse_id, u32 *response, u32 *info_type);
 int ele_generate_dek_blob(u32 key_id, u32 src_paddr, u32 dst_paddr, u32 max_output_size);
 int ele_dump_buffer(u32 *buffer, u32 buffer_length);
diff --git a/arch/arm/mach-imx/ele_ahab.c b/arch/arm/mach-imx/ele_ahab.c
index d02316ed6cb..e1946467468 100644
--- a/arch/arm/mach-imx/ele_ahab.c
+++ b/arch/arm/mach-imx/ele_ahab.c
@@ -625,6 +625,31 @@ static int do_ahab_return_lifecycle(struct cmd_tbl *cmdtp, int flag, int argc, c
 	return CMD_RET_SUCCESS;
 }
 
+static int do_ahab_derive(struct cmd_tbl *cmdtp, int flag, int argc,
+			  char *const argv[])
+{
+	ulong key;
+	size_t key_size;
+	char *seed = "_ELE_AHAB_SEED_";
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+
+	key = hextoul(argv[1], NULL);
+	key_size = simple_strtoul(argv[2], NULL, 10);
+	if (key_size != 16 && key_size != 32) {
+		printf("key size can only be 16 or 32\n");
+		return CMD_RET_FAILURE;
+	}
+
+	if (ele_derive_huk((u8 *)key, key_size, seed)) {
+		printf("Error in AHAB derive\n");
+		return CMD_RET_FAILURE;
+	}
+
+	return CMD_RET_SUCCESS;
+}
+
 static int do_ahab_commit(struct cmd_tbl *cmdtp, int flag, int argc,
 			  char *const argv[])
 {
@@ -681,6 +706,12 @@ U_BOOT_CMD(ahab_return_lifecycle, CONFIG_SYS_MAXARGS, 1, do_ahab_return_lifecycl
 	   "addr - Return lifecycle message block signed by OEM SRK\n"
 );
 
+U_BOOT_CMD(ahab_derive, CONFIG_SYS_MAXARGS, 3, do_ahab_derive,
+	   "Derive the hardware unique key",
+	   "addr [16|32]\n"
+	   "Store at addr the derivation of the HUK on 16 or 32 bytes.\n"
+);
+
 U_BOOT_CMD(ahab_commit, CONFIG_SYS_MAXARGS, 1, do_ahab_commit,
 	   "commit into the fuses any new SRK revocation and FW version information\n"
 	   "that have been found into the NXP (ELE FW) and OEM containers",
diff --git a/drivers/misc/imx_ele/ele_api.c b/drivers/misc/imx_ele/ele_api.c
index e0ec22c7abf..0eaf51e31c8 100644
--- a/drivers/misc/imx_ele/ele_api.c
+++ b/drivers/misc/imx_ele/ele_api.c
@@ -1,12 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright 2020, 2023 NXP
+ * Copyright 2024 Mathieu Othacehe <othacehe at gnu.org>
  *
  */
 
 #include <common.h>
 #include <hang.h>
 #include <malloc.h>
+#include <memalign.h>
 #include <asm/io.h>
 #include <dm.h>
 #include <asm/mach-imx/ele_api.h>
@@ -528,6 +530,77 @@ int ele_start_rng(void)
 	return ret;
 }
 
+int ele_derive_huk(u8 *key, size_t key_size, u8 *seed)
+{
+	struct udevice *dev = gd->arch.ele_dev;
+	struct ele_msg msg;
+	int msg_size = sizeof(struct ele_msg);
+	const size_t seed_size = 16;
+	u8 *seed_aligned, *key_aligned;
+	int ret, size;
+
+	if (!dev) {
+		printf("ele dev is not initialized\n");
+		return -ENODEV;
+	}
+
+	if (key_size != 16 && key_size != 32) {
+		printf("key size can only be 16 or 32\n");
+		return -EINVAL;
+	}
+
+	seed_aligned = memalign(ARCH_DMA_MINALIGN, seed_size);
+	if (!seed_aligned) {
+		printf("failed to alloc memory\n");
+		return -EINVAL;
+	}
+	memcpy(seed_aligned, seed, seed_size);
+
+	key_aligned = memalign(ARCH_DMA_MINALIGN, key_size);
+	if (!key_aligned) {
+		printf("failed to alloc memory\n");
+		ret = -EINVAL;
+		goto ret_seed;
+	}
+
+	size = ALIGN(seed_size, ARCH_DMA_MINALIGN);
+	flush_dcache_range((ulong)seed_aligned,
+			   (ulong)seed_aligned + size);
+
+	size = ALIGN(key_size, ARCH_DMA_MINALIGN);
+	invalidate_dcache_range((ulong)key_aligned,
+				(ulong)key_aligned + size);
+
+	msg.version = ELE_VERSION;
+	msg.tag = ELE_CMD_TAG;
+	msg.size = 7;
+	msg.command = ELE_CMD_DERIVE_KEY;
+	msg.data[0] = upper_32_bits((ulong)key_aligned);
+	msg.data[1] = lower_32_bits((ulong)key_aligned);
+	msg.data[2] = upper_32_bits((ulong)seed_aligned);
+	msg.data[3] = lower_32_bits((ulong)seed_aligned);
+	msg.data[4] = seed_size << 16 | key_size;
+	msg.data[5] = compute_crc(&msg);
+
+	ret = misc_call(dev, false, &msg, msg_size, &msg, msg_size);
+	if (ret) {
+		printf("Error: %s: ret %d, response 0x%x\n",
+		       __func__, ret, msg.data[0]);
+		goto ret_key;
+	}
+
+	invalidate_dcache_range((ulong)key_aligned,
+				(ulong)key_aligned + size);
+	memcpy(key, key_aligned, key_size);
+
+ret_key:
+	free(key_aligned);
+ret_seed:
+	free(seed_aligned);
+
+	return ret;
+}
+
 int ele_commit(u16 fuse_id, u32 *response, u32 *info_type)
 {
 	struct udevice *dev = gd->arch.ele_dev;
-- 
2.45.2