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From: Stefan Roese <sr@denx.de>
To: "Pali Rohár" <pali@kernel.org>
Cc: u-boot@lists.denx.de
Subject: Re: [PATCH v2 2/2] cmd: mvebu/bubt: Check for A38x/A37xx OTP secure bits and secure boot
Date: Wed, 17 Aug 2022 08:14:59 +0200	[thread overview]
Message-ID: <cca5a986-c2bf-ec4f-3e52-c7e59de0bf4f@denx.de> (raw)
In-Reply-To: <20220809194203.29903-2-pali@kernel.org>

On 09.08.22 21:42, Pali Rohár wrote:
> For obvious reasons BootROMS rejects unsigned images when secure boot is
> enabled in OTP secure bits. So check for OPT secure bits and do not allow
> flashing unsigned images when secure boot is enabled. Access to OTP via
> U-Boot fuse API is currently implemented only for A38x and A37xx SoCs.
> 
> Additionally Armada 3700 BootROM rejects signed trusted image when secure
> boot is not enabled in OTP. So add also check for this case. On the other
> hand Armada 38x BootROM acceps images with secure boot header when secure
> boot is not enabled in OTP.
> 
> OTP secure bits may have burned also boot device source. Check it also and
> reject flashing images to target storage which does not match OTP.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

> ---
> Changes in v2:
> * Add missing dependency on MVEBU_EFUSE
> * Use only for A38x and A37xx
> ---
>   cmd/mvebu/Kconfig |   1 +
>   cmd/mvebu/bubt.c  | 127 +++++++++++++++++++++++++++++++++++++++++++---
>   2 files changed, 120 insertions(+), 8 deletions(-)
> 
> diff --git a/cmd/mvebu/Kconfig b/cmd/mvebu/Kconfig
> index 120397d6d4d0..9ec3aa983a51 100644
> --- a/cmd/mvebu/Kconfig
> +++ b/cmd/mvebu/Kconfig
> @@ -5,6 +5,7 @@ config CMD_MVEBU_BUBT
>   	bool "bubt"
>   	select SHA256 if ARMADA_3700
>   	select SHA512 if ARMADA_3700
> +	select MVEBU_EFUSE if ARMADA_38X || ARMADA_3700
>   	help
>   	  bubt - Burn a u-boot image to flash
>   	  For details about bubt command please see the documentation
> diff --git a/cmd/mvebu/bubt.c b/cmd/mvebu/bubt.c
> index 3b6ffb7ffd1f..feb1e778a98c 100644
> --- a/cmd/mvebu/bubt.c
> +++ b/cmd/mvebu/bubt.c
> @@ -13,6 +13,8 @@
>   #include <vsprintf.h>
>   #include <errno.h>
>   #include <dm.h>
> +#include <fuse.h>
> +#include <mach/efuse.h>
>   
>   #include <spi_flash.h>
>   #include <spi.h>
> @@ -121,6 +123,17 @@ struct a38x_main_hdr_v1 {
>   	u8  checksum;              /* 0x1F      */
>   };
>   
> +/*
> + * Header for the optional headers, version 1 (Armada 370/XP/375/38x/39x)
> + */
> +struct a38x_opt_hdr_v1 {
> +	u8	headertype;
> +	u8	headersz_msb;
> +	u16	headersz_lsb;
> +	u8	data[0];
> +};
> +#define A38X_OPT_HDR_V1_SECURE_TYPE	0x1
> +
>   struct a38x_boot_mode {
>   	unsigned int id;
>   	const char *name;
> @@ -706,6 +719,7 @@ static int check_image_header(void)
>   {
>   	u8 checksum;
>   	u32 checksum32, exp_checksum32;
> +	u32 offset, size;
>   	const struct a38x_main_hdr_v1 *hdr =
>   		(struct a38x_main_hdr_v1 *)get_load_addr();
>   	const size_t image_size = a38x_header_size(hdr);
> @@ -752,6 +766,38 @@ static int check_image_header(void)
>   	printf("Image checksum...OK!\n");
>   	return 0;
>   }
> +
> +#if defined(CONFIG_ARMADA_38X)
> +static int a38x_image_is_secure(const struct a38x_main_hdr_v1 *hdr)
> +{
> +	u32 image_size = a38x_header_size(hdr);
> +	struct a38x_opt_hdr_v1 *ohdr;
> +	u32 ohdr_size;
> +
> +	if (hdr->version != 1)
> +		return 0;
> +
> +	if (!hdr->ext)
> +		return 0;
> +
> +	ohdr = (struct a38x_opt_hdr_v1 *)(hdr + 1);
> +	do {
> +		if (ohdr->headertype == A38X_OPT_HDR_V1_SECURE_TYPE)
> +			return 1;
> +
> +		ohdr_size = (ohdr->headersz_msb << 16) | le16_to_cpu(ohdr->headersz_lsb);
> +
> +		if (!*((u8 *)ohdr + ohdr_size - 4))
> +			break;
> +
> +		ohdr = (struct a38x_opt_hdr_v1 *)((u8 *)ohdr + ohdr_size);
> +		if ((u8 *)ohdr >= (u8 *)hdr + image_size)
> +			break;
> +	} while (1);
> +
> +	return 0;
> +}
> +#endif
>   #else /* Not ARMADA? */
>   static int check_image_header(void)
>   {
> @@ -760,20 +806,58 @@ static int check_image_header(void)
>   }
>   #endif
>   
> +static u64 fuse_read_u64(u32 bank)
> +{
> +	u32 val[2];
> +	int ret;
> +
> +	ret = fuse_read(bank, 0, &val[0]);
> +	if (ret < 0)
> +		return -1;
> +
> +	ret = fuse_read(bank, 1, &val[1]);
> +	if (ret < 0)
> +		return -1;
> +
> +	return ((u64)val[1] << 32) | val[0];
> +}
> +
> +#if defined(CONFIG_ARMADA_3700)
> +static inline u8 maj3(u8 val)
> +{
> +	/* return majority vote of 3 bits */
> +	return ((val & 0x7) == 3 || (val & 0x7) > 4) ? 1 : 0;
> +}
> +#endif
> +
>   static int bubt_check_boot_mode(const struct bubt_dev *dst)
>   {
>   #if defined(CONFIG_ARMADA_3700) || defined(CONFIG_ARMADA_32BIT)
> -	int mode;
> +	int mode, secure_mode;
>   #if defined(CONFIG_ARMADA_3700)
>   	const struct tim_boot_flash_sign *boot_modes = tim_boot_flash_signs;
>   	const struct common_tim_data *hdr =
>   		(struct common_tim_data *)get_load_addr();
>   	u32 id = hdr->boot_flash_sign;
> +	int is_secure = hdr->trusted != 0;
> +	u64 otp_secure_bits = fuse_read_u64(1);
> +	int otp_secure_boot = ((maj3(otp_secure_bits >> 0) << 0) |
> +			       (maj3(otp_secure_bits >> 4) << 1)) == 2;
> +	unsigned int otp_boot_device = (maj3(otp_secure_bits >> 48) << 0) |
> +				       (maj3(otp_secure_bits >> 52) << 1) |
> +				       (maj3(otp_secure_bits >> 56) << 2) |
> +				       (maj3(otp_secure_bits >> 60) << 3);
>   #elif defined(CONFIG_ARMADA_32BIT)
>   	const struct a38x_boot_mode *boot_modes = a38x_boot_modes;
>   	const struct a38x_main_hdr_v1 *hdr =
>   		(struct a38x_main_hdr_v1 *)get_load_addr();
>   	u32 id = hdr->blockid;
> +#if defined(CONFIG_ARMADA_38X)
> +	int is_secure = a38x_image_is_secure(hdr);
> +	u64 otp_secure_bits = fuse_read_u64(EFUSE_LINE_SECURE_BOOT);
> +	int otp_secure_boot = otp_secure_bits & 0x1;
> +	unsigned int otp_boot_device = (otp_secure_bits >> 8) & 0x7;
> +#endif
>   #endif
>   
>   	for (mode = 0; boot_modes[mode].name; mode++) {
> @@ -786,15 +870,42 @@ static int bubt_check_boot_mode(const struct bubt_dev *dst)
>   		return -ENOEXEC;
>   	}
>   
> -	if (strcmp(boot_modes[mode].name, dst->name) == 0)
> -		return 0;
> +	if (strcmp(boot_modes[mode].name, dst->name) != 0) {
> +		printf("Error: image meant to be booted from \"%s\", not \"%s\"!\n",
> +		       boot_modes[mode].name, dst->name);
> +		return -ENOEXEC;
> +	}
>   
> -	printf("Error: image meant to be booted from \"%s\", not \"%s\"!\n",
> -	       boot_modes[mode].name, dst->name);
> -	return -ENOEXEC;
> -#else
> -	return 0;
> +#if defined(CONFIG_ARMADA_38X) || defined(CONFIG_ARMADA_3700)
> +	if (otp_secure_bits == (u64)-1) {
> +		printf("Error: cannot read OTP secure bits\n");
> +		return -ENOEXEC;
> +	} else {
> +		if (otp_secure_boot && !is_secure) {
> +			printf("Error: secure boot is enabled in OTP but image does not have secure boot header!\n");
> +			return -ENOEXEC;
> +		} else if (!otp_secure_boot && is_secure) {
> +#if defined(CONFIG_ARMADA_3700)
> +			/*
> +			 * Armada 3700 BootROM rejects trusted image when secure boot is not enabled.
> +			 * Armada 385 BootROM accepts image with secure boot header also when secure boot is not enabled.
> +			 */
> +			printf("Error: secure boot is disabled in OTP but image has secure boot header!\n");
> +			return -ENOEXEC;
>   #endif
> +		} else if (otp_boot_device && otp_boot_device != id) {
> +			for (secure_mode = 0; boot_modes[secure_mode].name; secure_mode++) {
> +				if (boot_modes[secure_mode].id == otp_boot_device)
> +					break;
> +			}
> +			printf("Error: boot source is set to \"%s\" in OTP but image is for \"%s\"!\n",
> +			       boot_modes[secure_mode].name ?: "unknown", dst->name);
> +			return -ENOEXEC;
> +		}
> +	}
> +#endif
> +#endif
> +	return 0;
>   }
>   
>   static int bubt_verify(const struct bubt_dev *dst)

Viele Grüße,
Stefan Roese

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr@denx.de

  reply	other threads:[~2022-08-17  6:15 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-05 15:48 [PATCH 1/2] cmd: mvebu/bubt: Check for A38x image data checksum Pali Rohár
2022-08-05 15:48 ` [PATCH 2/2] cmd: mvebu/bubt: Check for OTP secure bits and secure boot Pali Rohár
2022-08-09 19:42 ` [PATCH v2 1/2] cmd: mvebu/bubt: Check for A38x image data checksum Pali Rohár
2022-08-09 19:42   ` [PATCH v2 2/2] cmd: mvebu/bubt: Check for A38x/A37xx OTP secure bits and secure boot Pali Rohár
2022-08-17  6:14     ` Stefan Roese [this message]
2022-08-23  5:05     ` Stefan Roese
2022-08-23 12:44       ` Pali Rohár
2022-08-23 14:53         ` Stefan Roese
2022-08-17  6:14   ` [PATCH v2 1/2] cmd: mvebu/bubt: Check for A38x image data checksum Stefan Roese
2022-08-23 10:28   ` Stefan Roese
2022-08-23 12:38     ` Pali Rohár
2022-08-23 12:52 ` [PATCH v3 " Pali Rohár
2022-08-23 12:52   ` [PATCH v3 2/2] cmd: mvebu/bubt: Check for A38x/A37xx OTP secure bits and secure boot Pali Rohár
2022-09-13  6:58     ` Stefan Roese
2022-09-11 11:26   ` [PATCH v3 1/2] cmd: mvebu/bubt: Check for A38x image data checksum Pali Rohár
2022-09-13  6:51     ` Stefan Roese
2022-09-13  6:58   ` Stefan Roese

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