[PATCH] imx: ele_ahab: Add HUK derivation support

[Ye Li]

Hi Mathieu,


On 8/13/2024 2:32 PM, Mathieu Othacehe wrote:
> 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;

Please try to pass seed size as a parameter, not hard code it. So users 
can set different seed.


Best regards,

Ye Li

> +	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;