On Tue, Jun 18, 2024 at 09:03:37PM -0600, Simon Glass wrote: > Hi Tom, > > On Tue, 18 Jun 2024 at 08:15, Tom Rini <tr...@konsulko.com> wrote: > > > > On Tue, Jun 18, 2024 at 06:43:51AM -0600, Simon Glass wrote: > > > Hi Tom, > > > > > > On Mon, 17 Jun 2024 at 11:16, Tom Rini <tr...@konsulko.com> wrote: > > > > > > > > On Mon, Jun 17, 2024 at 07:53:22AM -0600, Simon Glass wrote: > > > > > Hi, > > > > > > > > > > On Sat, 15 Jun 2024 at 01:03, Ilias Apalodimas > > > > > <ilias.apalodi...@linaro.org> wrote: > > > > > > > > > > > > Hi Heinrich > > > > > > > > > > > > resending the reply, I accidentally sent half of the message... > > > > > > > > > > > > On Fri, 14 Jun 2024 at 12:04, Heinrich Schuchardt > > > > > > <xypron.g...@gmx.de> wrote: > > > > > > > > > > > > > > On 14.06.24 09:01, Ilias Apalodimas wrote: > > > > > > > > On Fri, 14 Jun 2024 at 09:59, Heinrich Schuchardt > > > > > > > > <xypron.g...@gmx.de> wrote: > > > > > > > >> > > > > > > > >> On 6/14/24 08:03, Ilias Apalodimas wrote: > > > > > > > >>> Hi Simon, > > > > > > > >>> > > > > > > > >>> On Mon, 10 Jun 2024 at 17:59, Simon Glass <s...@chromium.org> > > > > > > > >>> wrote: > > > > > > > >>>> > > > > > > > >>>> It does not make sense to enable all SHA algorithms unless > > > > > > > >>>> they are > > > > > > > >>>> needed. It bloats the code and in this case, causes > > > > > > > >>>> chromebook_link to > > > > > > > >>>> fail to build. That board does use the TPM, but not with > > > > > > > >>>> measured boot, > > > > > > > >>>> nor EFI. > > > > > > > >>>> > > > > > > > >>>> Since EFI_TCG2_PROTOCOL already selects these options, we > > > > > > > >>>> just need to > > > > > > > >>>> add them to MEASURED_BOOT as well. > > > > > > > >>>> > > > > > > > >>>> Note that the original commit combines refactoring and new > > > > > > > >>>> features, > > > > > > > >>>> which makes it hard to see what is going on. > > > > > > > >>>> > > > > > > > >>>> Fixes: 97707f12fda tpm: Support boot measurements > > > > > > > >>>> Signed-off-by: Simon Glass <s...@chromium.org> > > > > > > > >>>> --- > > > > > > > >>>> > > > > > > > >>>> Changes in v2: > > > > > > > >>>> - Put the conditions under EFI_TCG2_PROTOCOL > > > > > > > >>>> - Consider MEASURED_BOOT too > > > > > > > >>>> > > > > > > > >>>> boot/Kconfig | 4 ++++ > > > > > > > >>>> lib/Kconfig | 4 ---- > > > > > > > >>>> 2 files changed, 4 insertions(+), 4 deletions(-) > > > > > > > >>>> > > > > > > > >>>> diff --git a/boot/Kconfig b/boot/Kconfig > > > > > > > >>>> index 6f3096c15a6..b061891e109 100644 > > > > > > > >>>> --- a/boot/Kconfig > > > > > > > >>>> +++ b/boot/Kconfig > > > > > > > >>>> @@ -734,6 +734,10 @@ config LEGACY_IMAGE_FORMAT > > > > > > > >>>> config MEASURED_BOOT > > > > > > > >>>> bool "Measure boot images and configuration when > > > > > > > >>>> booting without EFI" > > > > > > > >>>> depends on HASH && TPM_V2 > > > > > > > >>>> + select SHA1 > > > > > > > >>>> + select SHA256 > > > > > > > >>>> + select SHA384 > > > > > > > >>>> + select SHA512 > > > > > > > >>>> help > > > > > > > >>>> This option enables measurement of the boot > > > > > > > >>>> process when booting > > > > > > > >>>> without UEFI . Measurement involves creating > > > > > > > >>>> cryptographic hashes > > > > > > > >>>> diff --git a/lib/Kconfig b/lib/Kconfig > > > > > > > >>>> index 189e6eb31aa..568892fce44 100644 > > > > > > > >>>> --- a/lib/Kconfig > > > > > > > >>>> +++ b/lib/Kconfig > > > > > > > >>>> @@ -438,10 +438,6 @@ config TPM > > > > > > > >>>> bool "Trusted Platform Module (TPM) Support" > > > > > > > >>>> depends on DM > > > > > > > >>>> imply DM_RNG > > > > > > > >>>> - select SHA1 > > > > > > > >>>> - select SHA256 > > > > > > > >>>> - select SHA384 > > > > > > > >>>> - select SHA512 > > > > > > > >>> > > > > > > > >>> I am not sure this is the right way to deal with your problem. > > > > > > > >>> The TPM main functionality is to measure and extend PCRs, so > > > > > > > >>> shaXXXX > > > > > > > >>> is really required. To make things even worse, you don't know > > > > > > > >>> the PCR > > > > > > > >>> banks that are enabled beforehand. This is a runtime config > > > > > > > >>> of the > > > > > > > >>> TPM. > > > > > > > >> > > > > > > > >> If neither MEASURED_BOOT nor EFI_TCG2_PROTOCOL is selected, > > > > > > > >> U-Boot > > > > > > > >> cannot extend PCRs. So it seems fine to let these two select > > > > > > > >> the > > > > > > > >> complete set of hashing algorithms. As Simon pointed out for > > > > > > > >> EFI_TCG2_PROTOCOL this is already done in > > > > > > > >> lib/efi_loader/Kconfig. > > > > > > > > > > > > > > > > It can. The cmd we have can extend those pcrs -- e.g tpm2 > > > > > > > > pcr_extend 8 > > > > > > > > 0xb0000000 > > > > > > > > > > That's pretty normal for U-Boot though, since we want to avoid lots of > > > > > growth for things people might want control over. We can enable or > > > > > disable the SHA for the board, if this functionality is used outside > > > > > of measured boot and tcg2, but someone is enabling the tpm command. > > > > > > > > > > > > > > > > > > > So this patch should also consider CMD_TPM_V2 and CMD_TPM_V1. > > > > > > > > > > > > > > TPM v1 only needs SHA-1. > > > > > > > > > > > > I still prefer to imply all algos. > > > > > > > > > > 'imply' would be OK in this case as I can disable it for that board. I > > > > > don't think it is in the spirit of U-Boot though. > > > > > > > > > > isn't someone checking the growth in U-Boot? Or do so few boards have > > > > > TPMs that it didn't register? The size growth was 3.2KB on > > > > > chromebook_link. > > > > > > > > As always, yes, nearly every PR (I don't check the ones that touch just > > > > a single board for example) gets a world build before/after. In this > > > > case I likely assumed that it was acceptable growth for enabling > > > > features. It sounds like some of the chromebook boards need to be > > > > setting the features to cause link failure if a size is exceeded? > > > > > > The problem is that some Intel platforms have binary blobs, so the > > > size isn't known unless you have a real blob. > > > > Alright, but can't we put in some limit based on what the current blobs > > are, or look at the last few blob releases and see if they change much > > in size and put something in? Other platforms have blobs and size > > limits... > > Yes we can duplicate the entry sizes from binman into Kconfig options. > But I am not a fan of that...two variables controlling the same thing > and both can break, with nothing to connect them other than the poor > user. > > I wonder if some magic could solve this, inferring limits from the > binman image. But that is getting into yet another domain...
I'm sorry, I just don't see what makes this case different from all of the other cases where we have to include blobs. We know there's X amount of flash available, blobs tend to take up Y and so we set BOARD_SIZE_LIMIT to Z where there's some room for growth in U-Boot but it takes in to account whatever limits the blobs place on us. -- Tom
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