[PATCH 1/4] tools: mkeficapsule: add firmwware image signing

[AKASHI Takahiro]

On Fri, May 14, 2021 at 08:59:38AM +0200, Heinrich Schuchardt wrote:
> On 5/14/21 8:19 AM, AKASHI Takahiro wrote:
> > On Thu, May 13, 2021 at 08:25:56PM +0200, Heinrich Schuchardt wrote:
> > > On 5/13/21 10:18 AM, Masami Hiramatsu wrote:
> > > > 2021年5月13日(木) 16:24 AKASHI Takahiro <takahiro.akashi at linaro.org>:
> > > > 
> > > > > > > > > BTW, IMHO, if u-boot.bin can not find the ESL in the device tree,
> > > > > > > > > it should skip authentication too.
> > > > > > > > 
> > > > > > > > In this case the capsule should be rejected (if
> > > > > > > > CONFIG_EFI_CAPSULE_AUTHENTICATE=y).
> > > > > > > 
> > > > > > > That's basically right.
> > > > > > > But as I mentioned in my comment against Sughosh's patch,
> > > > > > > the authentication process will be enforced only if the capsule has
> > > > > > > an attribute, IMAGE_ATTRIBUTE_AUTHENTICATION_REQUIRED.
> > > > > > > 
> > > > > > 
> > > > > > That would be a security desaster.
> > > > > 
> > > > > The requirement that I mentioned above is clearly described
> > > > > in UEFI specification.
> > > > > If you think that it is a disaster, please discuss the topic
> > > > > in UEFI Forum first.
> > > > 
> > > > I confirmed UEFI specification, version 2.7, Section.23.1
> > > > the last of EFI_FIRMWARE_MANAGEMENT_PROTOCOL.GetImageInfo()
> > > > 
> > > > -----------------
> > > > If IMAGE_ATTRIBUTE_AUTHENTICATION_REQUIRED is supported and clear, then
> > > > authentication is not required to perform the firmware image operations.
> > > > -----------------
> > > 
> > > IMAGE_ATTRIBUTE_AUTHENTICATION_REQUIRED bit is a property of the FMP driver.
> > 
> > Yes, it is. But if the attribute is not changeable at all,
> > why do we need this flag?
> > Why does a "firmware image descriptor" hold two distinct
> > member fields, "AttributesSupported" and "AttributesSetting"?
> > What does "Setting" mean? Who sets what, and when?
> 
> "Setting" means value here. None of these flags is set by the user. It
> is the FMP driver that keeps track of the update state and sets the
> flags accordingly.
> 
> AttributesSupported indicates which bits in AttributesSetting contain
> accurate information:
> 
> E.g for IMAGE_ATTRIBUTE_IN_USE
> 
> AttributesSupported | AttributesSetting | Meaning
> --------------------+-------------------+--------------------
> 0                   | 0                 | state is unknown
> 0                   | 1                 | state is unknown
> 1                   | 0                 | image is not in use
> 1                   | 1                 | image is in use

We are discussing *_REQUIRED.
Can you give me the same table for *_REQUIRED?

-Takahiro Akashi


> Some bits indicate a property of the installed image, e.g.
> IMAGE_ATTRIBUTE_UEFI_IMAGE.
> 
> Some bits indicate a system state. E.g. IMAGE_ATTRIBUTE_IN_USE indicates
> if the information reported by the FMP driver is for the currently used
> image. This bit might be 0 in AttributesSetting if you have not yet
> executed a reset after installing the new image and 1 after the reset.
> 
> Best regards
> 
> Heinrich
> > > 
> > > > 
> > > > Oh, this is really crazy because deciding whether to authenticate the
> > > > suspicious
> > > > package or not, depends on whether the package said "please
> > > > authenticate me" or not. :D
> > > > 
> > > > Anyway, since this behavior follows the specification, it should be
> > > > kept by default,
> > > > but also IMHO, there should be a CONFIG option to enforce capsule
> > > > authentication always.
> > > > 
> > > > Thank you,
> > > > 
> > > > 
> > > > 
> > > 
>