@securepaul I'll put an abstract about tpm2sh for LSS once there are CfP's available next year (and little bit about protocol stack I've build for it [1]). Has been a while but I haven't had really a topic I wanted to talk about for a long time :-)

[1] https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2-protocol.git

i don't know how those algorithms work - i just used the fact that hex digit maps to a nibble and compile bit pattern based on that observation...

https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2sh.git/tree/src/wildcard.rs?h=main

made a little wildcard parser last night so that I don’t have to implement docker esque “tpm2sh reset” command.

e.g. cache can be reseted now by tpm2sh delete 'vtpm:*'

@NanoRaptor it is awesome

386.

After starting this work one Sunday on August and ~13000 lines of new Rust code after that, this is the first release where I don't have any catastrophical bugs to resolve, or have personally any immediate needs :-)

https://crates.io/crates/tpm2sh

#linux #rustlang #tpm

tpm2sh policy has now more inituitive infix expressions :-) [learning nom by trial and error]

I’m planning to iteratively make tpm2sh policy subcommand to compile policy expressions first into eBPF i.e., --mode ebpf option.

We can use this to address bottleneck in trusted keys in kernel: TPMKey ASN.1 provides key blob but not steps how to create policy session that authorizes the key.

Today: TpmKey ASN.1 with auth value and policy digest can be passed but really only auth value (+ PCR selection in TPM2_Create) can be used for authentication.

My vision for policy protected keys is basically:

1. Key data is passed as TPMKey ASN.1 just like today.
2. In addition eBPF program for creation policy session is passed when policy digest is used.

It’s perfectly secure given that a malicious eBPF program would end up to a different policy digest than what is associated with the key.

#linux #kernel #tpm

policies:

Refined the interface of offloaded objects:

1. Objects resident/loaded in TPM: tpm:
2. Offloaded objects: vtpm:

Thus, I removed also "key" and "session" subcommands and introduced "virtual" subcommand.

#linux #tpm #rustlang

tpm2sh 0.11.16

This is the release where things mostly work and is first usable version for wider audience than just me.

Functionality is focused on key management and it is quite limited on operations.

That said, it the most important functionalities, and most difficult to implement, in place:

1. Implicit creation of HMAC sessions to protect communication, and hiding its complexity . It is still a stub as parameter encryption is not in place but the mechanism is working correctly.
2. Key management including direct support for PKCS#1, PKCS#8 and SEC1 external keys with custom parsers so that dependencies are light for e.g., BuildRoot embedded/VM targets. 3, Seamless over-subscription with key context cache (in ~/.cache/tpm2sh). Detects stale contexts from previous power cycles. “Cache keys” can be referred bit “key:<hex grip>” type of “URI”, where grip is 8 bytes of the key’s name hash.
3. Seamless policy sessions with policy command, which can output both composite digest and session handle.
4. Intuitive way to download vendor certificates from the chip.
5. Full support for the TPMKey ASN.1 format, which is what kernel speaks.

Adding signing etc. ops would have been worse mistake to do before getting this basis right.

It’s not aiming to do all what tpm2-tools does but more like do stuff that I want to do and implementing that as a command-line tool :-) I.

#linux #kernel #tpm #rustlang #buildroot

@andrew fixed since

@andrew yes it demonstrates known bug but actual function works :-)

known argument parsing bug but downloading certs does work :-)

PKCS#1, PKCS#8 and SEC1 parsers implemented with rasn and can be converted to TPMKey files, or loaded directly. I created my own parser because popular crates such pkcs8 do "so much more" than this tool needs.

I.e., it's the best tool at preparing stuff into blobs that are usable by kernel.

#buildroot i.e. edition 2021 compatible

https://codeberg.org/jarkko/linux-tpmdd-test/src/branch/main/package/tpm2sh/tpm2sh.mk

tpm2sh 0.11: https://crates.io/crates/tpm2sh/0.11.0

cli philosophy, which I should document to README.md, is that no nested subcommands thank you. That constraint enforces to do efficient subcommand design (IMHO).

#linux #kernel #tpm

Reasons why I wrote my own parsers for PKCS#1, SEC1 and PKCS#8 on top of awesome rasn [1] crate instead of using e.g., pkcs8 crate is that:

1. Usually generic crates do so much useless shit outside of the app's requirements so it might not be huge effort to make focused code tuned for the app.
2. Compilation times.
3. It gave me so much DOWNGRADE options, thanks to simpler depenencies, which is huge robustness addition. It's something you learn to appreciate once you do anything embedded/FPGA on ANY language.

[1] https://github.com/librasn/rasn

#linux #rustlang #tpm

I did not know I was this far with loading PKCS#8 keys as I was fully focus for few weeks on TPM2_Import:

https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2sh.git/commit/?h=main&id=9b4e31f8bea02953d56d8243a1b9157096642c54

I.e. I had enough parsing code to tell the user that PKCS#8 is not supported that I could now just as well just plain load them ;-)

#linux #tpm

I'm now in zero known bugs state with tpm2sh so maybe it is good soon to release 0.11, which is first real release TBH. Previous were test code for tpm2-protocol

External key loading and import was like something I debugged ridiculous amount of times but considering how many openssl commands you need to do to achieve same result, I'm pretty happy :-)

I also stick to SEC1 and PKCS#1 simply because this is not openssl, and you can use other tools to convert keys to these formats. This allows me NOT to use crazy complex loader crates like pkcs8 crate and have my fully custom loaders made using rasn crate.

#linux #tpm