[PATCH v2] cmd: bootefi: restore ability to boot arbitrary blob

[Heinrich Schuchardt]

On 5/19/22 02:35, AKASHI Takahiro wrote:
> I thought I had sent out my comment when this patch was submitted first time,
> but it seems that it has never reached out to ML.
>
> On Sun, Apr 10, 2022 at 04:05:55PM -0500, kevans at FreeBSD.org wrote:
>> From: Kyle Evans <kevans at FreeBSD.org>
>>
>> Up until commit 5f59518a7b1ae ("efi_loader: setting boot device"), we
>> could boot an arbitrary blob with bootefi.  Indeed, efi_run_image() even
>> has a special case for missing device paths indicating a payload that
>> was directly loaded via JTAG, for example.
>>
>> Restore the ability to inject a UEFI payload into memory and `bootefi`
>> it.  If the address passed isn't the last PE-COFF loaded, then we'll
>> wipe out the pre-existing DP/Image information and let efi_run_image()
>> synthesize a memory device path.
>>
>> An image size is required if we're booting an arbitrary payload, and
>> the FDT argument has been changed to accept `-`.  The size could be
>> deduced from the image header, but it's required anyways as an explicit
>> acknowledgment that one's trying to boot an arbitrary payload rather
>> than accidentally using the wrong address in the single-addr form.
>
> The syntax seems to be odd and I don't think it is user-friendly
>     	"<image address> [fdt address [image size]]\n"
> as an image-related parameter,<image size>, doesn't follow <address>
> immediately but comes *after* <fdt address>.
>
> Instead, I would suggest
>      bootefi <image addr>[:<image size>] [<fdt addr>]
>      (or     [<image size>@]<image addr>)
>
> I believe that "<addr>:<size>" notation is quite intuitive and non-misleading.
> Moreover, a similar syntax can be seen, for example, in booti command.

I will create a patch for this.

Best regards

Heinrich

>
> -Takahiro Akashi
>
>> If the image address matches the last loaded PE_COFF, it is an error
>> to pass the incorrect size (but the size may be omitted).
>>
>> Signed-off-by: Kyle Evans <kevans at FreeBSD.org>
>> ---
>>
>> Changes since v1:
>>   - Specifying an address that isn't the last-known without a size produces the
>>      same error as in the past ("No UEFI binary known at ...")
>>   - Specifying a size with the last known address that doesn't match the last
>>      recorded size will get: Size does not match known UEFI binary at %s
>>
>>   cmd/bootefi.c | 42 ++++++++++++++++++++++++++++++++++--------
>>   1 file changed, 34 insertions(+), 8 deletions(-)
>>
>> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
>> index 53d9f0e0dc..0d3aecb2a1 100644
>> --- a/cmd/bootefi.c
>> +++ b/cmd/bootefi.c
>> @@ -425,7 +425,7 @@ static int do_efibootmgr(void)
>>    * @image_opt:	string of image start address
>>    * Return:	status code
>>    */
>> -static int do_bootefi_image(const char *image_opt)
>> +static int do_bootefi_image(const char *image_opt, const char *size_opt)
>>   {
>>   	void *image_buf;
>>   	unsigned long addr, size;
>> @@ -444,13 +444,35 @@ static int do_bootefi_image(const char *image_opt)
>>   		if (!addr)
>>   			return CMD_RET_USAGE;
>>
>> +		size = 0;
>> +		if (size_opt) {
>> +			size = strtoul(size_opt, NULL, 16);
>> +			/* Check that a numeric value was passed */
>> +			if (!size)
>> +				return CMD_RET_USAGE;
>> +		}
>> +
>>   		image_buf = map_sysmem(addr, 0);
>>
>>   		if (image_buf != image_addr) {
>> -			log_err("No UEFI binary known at %s\n", image_opt);
>> -			return CMD_RET_FAILURE;
>> +			/* Fake device path -- we must have a size. */
>> +
>> +			if (size == 0) {
>> +				printf("No UEFI binary known at %s\n", image_opt);
>> +				return CMD_RET_FAILURE;
>> +			}
>> +
>> +			if (image_addr)
>> +				efi_clear_bootdev();
>> +		} else {
>> +			if (size != 0 && size != image_size) {
>> +				printf("Size does not match known UEFI binary at %s\n",
>> +				       image_opt);
>> +				return CMD_RET_FAILURE;
>> +			}
>> +
>> +			size = image_size;
>>   		}
>> -		size = image_size;
>>   	}
>>   	ret = efi_run_image(image_buf, size);
>>
>> @@ -654,7 +676,7 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
>>   		return CMD_RET_FAILURE;
>>   	}
>>
>> -	if (argc > 2) {
>> +	if (argc > 2 && strcmp(argv[2], "-") != 0) {
>>   		uintptr_t fdt_addr;
>>
>>   		fdt_addr = hextoul(argv[2], NULL);
>> @@ -677,15 +699,19 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
>>   		return do_efi_selftest();
>>   #endif
>>
>> -	return do_bootefi_image(argv[1]);
>> +	return do_bootefi_image(argv[1], argc > 3 ? argv[3] : NULL);
>>   }
>>
>>   #ifdef CONFIG_SYS_LONGHELP
>>   static char bootefi_help_text[] =
>> -	"<image address> [fdt address]\n"
>> +	"<image address> [fdt address [image size]]\n"
>>   	"  - boot EFI payload stored at address <image address>.\n"
>>   	"    If specified, the device tree located at <fdt address> gets\n"
>>   	"    exposed as EFI configuration table.\n"
>> +	"    The image size is required if this is not a preloaded image, but\n"
>> +	"    it must be omitted if the image was preloaded.\n"
>> +	"    The <fdt address> parameter accepts '-' to indicate FDT already\n"
>> +	"    installed or pre-specified in fdt_addr or fdtcontroladdr.\n"
>>   #ifdef CONFIG_CMD_BOOTEFI_HELLO
>>   	"bootefi hello\n"
>>   	"  - boot a sample Hello World application stored within U-Boot\n"
>> @@ -707,7 +733,7 @@ static char bootefi_help_text[] =
>>   #endif
>>
>>   U_BOOT_CMD(
>> -	bootefi, 3, 0, do_bootefi,
>> +	bootefi, 4, 0, do_bootefi,
>>   	"Boots an EFI payload from memory",
>>   	bootefi_help_text
>>   );
>> --
>> 2.33.0
>>