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Linux kernel hacker and maintainer etc.

OpenPGP: 3AB05486C7752FE1

Jarkko Sakkinen

awesome, new milestone reached: tpm2sh and tpm2-protocol compile with the Rust toolchain of Buildroot 2025.02.6.

Couple of recursive dependencies needed to be downgraded, and some code tweaks but nothing heavy (phew). I also found that even you set your edition to 2021, the chances are that there is some nested dependency that is allowed to be in edition 2024.

#buildroot
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Jarkko Sakkinen

A good exercise for Rust code IMHO in order to get it to the level that actually is fluent in production is to create BuildRoot package for it ;-)

All sorts of minor tweaks have had to done for tpm2sh and tpm2-protocol in order to get them to my kernel testing images.

Or at least a good exercise if planning to target and scale Rust crate to embedded systems (in production).

#buildroot #rust
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Jarkko Sakkinen

Edited 18 days ago
I've started to support more proactively TrenchBoot efforts because D-RTM despite being a bit rough compared to enclaves, is at least fully open. It also draws me a positive picture about Oracle as a company as it proves to me that they push technologies to upstream that don't only support Oracle's proprietary technologies but also is benefical work for the wider developer ecosystem (unlike e.g., Intel and AMD). It's good cause IMHO plain and simple.
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Jarkko Sakkinen

my favorite patches are those that rip of over 100 lines of code :-) https://lore.kernel.org/linux-integrity/20250919112448.2543343-1-jarkko@kernel.org/T/#u
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Jarkko Sakkinen

Edited 18 days ago
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expected too that there's end boss fight with different external key types, such as PKCS#8 and SEC1 and import ;-) this will slowly uncover...
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there's a bug with import on "rsa parent + ecc child" that i'm debugging other than that this start to look soon release ready.
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Jarkko Sakkinen

"precious oneliners" ;-) had to go look this up from lore

make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 tinyconfig && ./scripts/config --file .config -e CONFIG_KEYS -e CONFIG_TCG_TPM -e CONFIG_64BIT -e CONFIG_TRUSTED_KEYS -e CONFIG_TTY -e CONFIG_PROCFS -e CONFIG_SYSFS -e CONFIG_TCG_VTPM_PROXY -e CONFIG_EFI -e CONFIG_ACPI -e CONFIG_ARM_FFA_TRANSPORT -e CONFIG_TCG_CRB && yes '' | make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 oldconfig && make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 -j$(nproc)
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Jarkko Sakkinen

Edited 19 days ago
I'm planning a new kernel feature based on patch set that I never finished:

https://lore.kernel.org/linux-integrity/aMwh95tMxB7sMEzy@kernel.org/

The gist is to harden selected AIKs, and perform signing and quotes through kernel, and filtered out from /dev/tpm0.

They'd be wrapped into keyring asymmetric keys. You can lock-in remote attestation pretty well then with UKI images having signed command-line.
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Jarkko Sakkinen

Edited 20 days ago

getting hmac session together in tpm2sh:

❯ sudo target/debug/tpm2sh start-session -s hmac
data://utf8,session(handle=0x02000000;nonce=d19da78d903f3c3a2350b857da368ba02eb911bc2dfe307435e0eec9621083bd;attrs=00;key=1abf23e3cb74a40b1b093f5a7fbad330dc0f63c51e415f4523d98122e507a3b0;alg=sha256)

There used to be session:// but I migrated sessions as portion of the policy expression language grammar. Previously I migrated from pcr:// to language constructs.

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Jarkko Sakkinen

if there is one open source project, which i hope to succeed more than any other project, it must be Servo. it's super important that it will become game changer and real distruptor.
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Jarkko Sakkinen

Edited 21 days ago

i realized that you an do mustache templates with just plain jq:

jq -n -r \
  --arg domains "$TENANT_DOMAIN" \
  --arg hsm_type "$HSM_TYPE" \
  --argjson enable_hello "$ENABLE_HELLO" \
  '
    "[global]\ndebug = true\ndomains = \($domains)\nhome_alias = CN\nhome_attr = CN\nid_attr_map = name\npam_allow_groups =\nuse_etc_skel = true\nlocal_groups = users\nhsm_type = \($hsm_type)\nenable_hello = \($enable_hello)"
  ' > "$BUILD_DIR/himmelblau.conf"

need to apply this idea to my kernel pull request scripts :-)

template here is:

[global]
debug = true
domains = {{domains}}
home_alias = CN
home_attr = CN
id_attr_map = name
pam_allow_groups =
use_etc_skel = true
local_groups = users
hsm_type = {{hsm_type}}
enable_hello = {{enable_hello}}
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because bash is my top 3 favorite programming languages and favorite scripting language :-)
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Jarkko Sakkinen

I've been thinking that post 0.11 tpm2sh cool feature would be remote attestation and demo would be remote attestation client and server in bash.
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I'll likely fix those glitches within a week or so and then it's ready for release :-)

The key insight here is that 50% of hardware is realized the software that creates interface for it, and for TPM2 the "software defined object" portion has been quite horrible :-) And it's pretty bad across the board form programming interfaces to tooling with absolutely no developer or sysadmin ergonomics consider anywhere.

On the other hand, by having right kind of software interface for TPM2, makes it like it was a completely new piece of hardware that did not exist before. I.e. not a brick.
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Jarkko Sakkinen

Edited 21 days ago
yay, now tpm2sh has software digest calculator for policy expressions (which can query e.g. PCR values but does not exercise policy tpm commands), the remaining errata is not a huge stretch:

https://github.com/puavo-org/tpm2sh/issues/2

Many of the things are just minor collapses while turning this over and over again. Sessions need still a bit of work but lot of the functionality is already there...

I'd like to add quote generation etc. for Remote Attestation purposes but it is definitely out of scope and better just to stabilize the command set.

Sessions are represented like this (to be cosmetic tweaked in some places):

session://handle=0x02000000;nonce=135eac83db00e0c691fba1653405e79f8f285964e18add0488337fc7caf90606;attrs=00;key=;alg=sha256

And there's already `--session` argument but further I'll add an environment variable TPM2SH_SESSION, which command not only read but also update (to enable chaining e.g., nonce needs to be updated).

The general gist and main goal of the command set and "command-line experience" is to enable both user interactive experience and also TPM2 access for shell implemented tools such as password managers.

Load loads both external PKCS#8 and TPM ASN.1. Convert command converts PKCS#8 to TPM ASN.1.

So instead of this:

tpm2_createprimary --hierarchy o -G rsa2048 -c owner.txt
tpm2_evictcontrol -c owner.txt 0x81000001
openssl genrsa -out private.pem 2048
tpm2_import -C 0x81000001 -G rsa -i private.pem -u key.pub -r key.priv
tpm2_encodeobject -C 0x81000001 -u key.pub -r key.priv -o key.priv.pem
openssl asn1parse -inform pem -in key.priv.pem -noout -out key.priv.der

You can just:

tpm2sh create-primary rsa:2048:sha256 --output file://owner.txt
openssl genrsa -out private.pem 2048
tpm2sh convert --parent "tpm://0x81000001" file://private.pem --output file://key.priv.der

#linux #rust #tpm
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and just like during winter war this is one thing where the thinking is universal for far right to left: putinists don't have future in finnish politics and governing. it is outside of scope of the usual political debate.
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