[U-Boot] [PATCH v2] imx: hab: extend hab_auth_img to calculate ivt_offset

[Parthiban Nallathambi]

Hi Breno,

On 11/21/18 7:42 PM, Breno Matheus Lima wrote:
> Hi Parthiban,
> 
> Em qua, 21 de nov de 2018 às 15:52, Parthiban Nallathambi <pn at denx.de> escreveu:
>>
>> Hi Breno,
>>
>> On 11/21/18 5:45 PM, Breno Matheus Lima wrote:
>>> Hi Parthiban,
>>>
>>> Em qua, 21 de nov de 2018 às 11:50, Parthiban Nallathambi <pn at denx.de> escreveu:
>>>>
>>>> Current implementation of hab_auth_img command needs ivt_offset to
>>>> authenticate the image. But ivt header is placed at the end of image
>>>> date after padding.
>>>>
>>>> This leaves the usage of hab_auth_img command to fixed size or static
>>>> offset for ivt header. New function "get_image_ivt_offset" is introduced
>>>> to find the ivt offset during runtime. The case conditional check in this
>>>> function is same as boot_get_kernel in common/bootm.c
>>>>
>>>> With this variable length image e.g. FIT image with any random size can
>>>> have IVT at the end and ivt_offset option can be left optional
>>>>
>>>> Can be used as "hab_auth_img $loadaddr $filesize" from u-boot script
>>>>
>>>> Signed-off-by: Parthiban Nallathambi <pn at denx.de>
>>>> ---
>>>>
>>>> Notes:
>>>>      Changelog in v2:
>>>>      - Finding IVT offset doesn't need length. Removed the
>>>>      length argument from get_image_ivt_offset
>>>>
>>>>   arch/arm/mach-imx/hab.c | 29 +++++++++++++++++++++++++++--
>>>>   1 file changed, 27 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/mach-imx/hab.c b/arch/arm/mach-imx/hab.c
>>>> index b88acd13da..dbfd692fa3 100644
>>>> --- a/arch/arm/mach-imx/hab.c
>>>> +++ b/arch/arm/mach-imx/hab.c
>>>> @@ -6,6 +6,8 @@
>>>>   #include <common.h>
>>>>   #include <config.h>
>>>>   #include <fuse.h>
>>>> +#include <mapmem.h>
>>>> +#include <image.h>
>>>>   #include <asm/io.h>
>>>>   #include <asm/system.h>
>>>>   #include <asm/arch/clock.h>
>>>> @@ -302,18 +304,41 @@ static int do_hab_status(cmd_tbl_t *cmdtp, int flag, int argc,
>>>>          return 0;
>>>>   }
>>>>
>>>> +static ulong get_image_ivt_offset(ulong img_addr)
>>>> +{
>>>> +       const void *buf;
>>>> +
>>>> +       buf = map_sysmem(img_addr, 0);
>>>> +       switch (genimg_get_format(buf)) {
>>>> +#if defined(CONFIG_IMAGE_FORMAT_LEGACY)
>>>> +       case IMAGE_FORMAT_LEGACY:
>>>> +               return (image_get_image_size((image_header_t *)img_addr)
>>>> +                       + 0x1000 - 1)  & ~(0x1000 - 1);
>>>> +#endif
>>>> +#if IMAGE_ENABLE_FIT
>>>> +       case IMAGE_FORMAT_FIT:
>>>> +               return (fit_get_size(buf) + 0x1000 - 1)  & ~(0x1000 - 1);
>>>> +#endif
>>>> +       default:
>>>> +               return 0;
>>>> +       }
>>>> +}
>>>
>>>
>>> Do you have more details about the image header I should use here?
>>
>> Is the image signed using CST or similar tool? Is so, the signature data
>> (HAB data: CSF, Certs and signature) pads at the end of the kernel
>> image.
> 
> Yes, my Kernel image contains an IVT and is signed with CST. The image
> layout looks like link below:
> https://pastebin.com/5qEt7ETa
> 
>>
>>>
>>> I'm trying to get the IVT offset for my Kernel image based on NXP
>>> 4.9.11_2.0.0_GA Linux release loaded at 0x80800000:
>>>
>>> => fatload mmc 0:1 0x80800000 zImage
>>> => hab_auth_img 0x80800000 <Len not being used>
>>
>> Length for hab_auth_img is still mandatory. Length hear means the file
>> size or total length of the image, this is required for the HAB API to
>> authenticate (HAB_RVT_AUTHENTICATE_IMAGE).
> 
> Oh ok, I understood the scenario right now.
> 
>>From my first overview I thought we would add IVT_SIZE + CSF_PAD_SIZE
> in ivt_offset to calculate the image length, similar approach we have
> in spl.c:
> http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/mach-imx/spl.c;h=a20b30d154d788e4ebd4e22e9a6568a4f24c057e;hb=HEAD#l226
> 
> In this case only load addr would be necessary.
> 
>>
>>>
>>> The zImage size in Header looks correct (0x00726690), but
>>> get_image_ivt_offset() is returning 0x0
>>
>> Looks like IVT offset is not found in the image.
>>
>>>
>>> $ hexdump zImage | head
>>> 0000000 0000 e1a0 0000 e1a0 0000 e1a0 0000 e1a0
>>> *
>>> 0000020 0003 ea00 2818 016f 0000 0000 6690 0072
>>> 0000030 0201 0403 9000 e10f 04f8 eb00 7001 e1a0
>>> 0000040 8002 e1a0 2000 e10f 0003 e312 0001 1a00
>>>
>>> Seems that genimg_get_format() is returning 0x0.
>>
>> Image is not signed?
> 
> No, my zImage is signed.
> 
>>
>>>
>>> Any ideias if I'm missing something?
>>>
>>>> +
>>>>   static int do_authenticate_image(cmd_tbl_t *cmdtp, int flag, int argc,
>>>>                                   char * const argv[])
>>>>   {
>>>>          ulong   addr, length, ivt_offset;
>>>>          int     rcode = 0;
>>>>
>>>> -       if (argc < 4)
>>>> +       if (argc < 3)
>>>
>>> I think we can also change here to argc < 2, the function
>>> get_image_ivt_offset() only requires the img addr now.
>>
>> No, length is mandatory for authentication. To brief, this patch just
>> removes the ivt_offset as argument and make it optional. This is needed
>> because, in images like FIT, the location of the ivt header varies
>> dynamically depending on the total number of images clubbed.
>>
>> In such cases, the existing hab_auth_img is hard to use as ivt header
>> offset needs to be pre-calculated everytime and fed into.
> 
> Yes I understood your scenario right now, as I stated above I thought
> your patch would also calculate the image length as we have in spl.c.
> 
> I'm only wondering why genimg_get_format() is returning
> IMAGE_FORMAT_INVALID, do you happen to know if zImage header should
> return IMAGE_FORMAT_LEGACY?

No, LEGACY directly checks for uImage magic "0x27051956". In general,
genimg_get_format handles only uImage, fitimage and android magic alone.

> 
> Thanks,
> Breno Lima
> 

-- 
Thanks,
Parthiban N

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