[v5,0/5] KEYS: asymmetric: tpm2_key_rsa

Message

Jarkko Sakkinen May 23, 2024, 9:25 p.m. UTC

## Overview

Introduce tpm2_key_rsa module, which implements asymmetric TPM2 RSA key.
The feature can be enabled with the CONFIG_ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE 
kconfig option. This feature allows the private key to be uploaded to
the TPM2 for signing, and software can use the public key to verify
the signatures.

The idea in the design is to over time to have submodule per key type
For instance, tpm2_key_ecdsa could be one potential future addition in
the future. Perhaps, it might sense to consider at that point also a
top-level tpm2_key module. The gist is that the naming convention is
free from potential future bottlencks.

### Testing

tpm2_createprimary --hierarchy o -G rsa2048 -c owner.txt
tpm2_evictcontrol -c owner.txt 0x81000001
tpm2_getcap handles-persistent
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
serial=`cat key.priv.der | keyctl padd asymmetric tpm @u`
echo "abcdefg" > plaintext.txt
keyctl pkey_encrypt $serial 0 plaintext.txt enc=pkcs1 > encrypted.dat
keyctl pkey_decrypt $serial 0 encrypted.dat enc=pkcs1 > decrypted.dat
keyctl pkey_sign $serial 0 plaintext.txt enc=pkcs1 hash=sha256 > signed.dat
keyctl pkey_verify $serial 0 plaintext.txt signed.dat enc=pkcs1 hash=sha256

## References

- v4: https://lore.kernel.org/linux-integrity/[e-mail]/
- v3: https://lore.kernel.org/linux-integrity/[e-mail]/
- v2: https://lore.kernel.org/linux-integrity/[e-mail]/
- v1: https://lore.kernel.org/linux-integrity/[e-mail]/
- Derived from https://lore.kernel.org/all/[e-mail]/

James Prestwood (1):
  keys: asymmetric: ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE

Jarkko Sakkinen (4):
  crypto: rsa-pkcs1pad: export rsa1_asn_lookup()
  KEYS: trusted: Change -EINVAL to -E2BIG
  KEYS: trusted: Move tpm2_key_decode() to the TPM driver
  tpm: tpm2_key: Extend parser to TPM_LoadableKey

 crypto/asymmetric_keys/Kconfig                |  15 +
 crypto/asymmetric_keys/Makefile               |   1 +
 crypto/asymmetric_keys/tpm2_key_rsa.c         | 680 ++++++++++++++++++
 crypto/rsa-pkcs1pad.c                         |  16 +-
 drivers/char/tpm/Kconfig                      |   1 +
 drivers/char/tpm/Makefile                     |   5 +
 drivers/char/tpm/tpm2_key.c                   | 118 +++
 .../char/tpm}/tpm2key.asn1                    |   0
 include/crypto/rsa-pkcs1pad.h                 |  20 +
 include/crypto/tpm2_key.h                     |  35 +
 include/linux/tpm.h                           |   2 +
 security/keys/trusted-keys/Makefile           |   2 -
 security/keys/trusted-keys/trusted_tpm2.c     | 131 +---
 13 files changed, 908 insertions(+), 118 deletions(-)
 create mode 100644 crypto/asymmetric_keys/tpm2_key_rsa.c
 create mode 100644 drivers/char/tpm/tpm2_key.c
 rename {security/keys/trusted-keys => drivers/char/tpm}/tpm2key.asn1 (100%)
 create mode 100644 include/crypto/rsa-pkcs1pad.h
 create mode 100644 include/crypto/tpm2_key.h

Comments

Jarkko Sakkinen May 24, 2024, 9:18 a.m. UTC | #1

On Fri May 24, 2024 at 12:25 AM EEST, Jarkko Sakkinen wrote:
> ## Overview
>
> Introduce tpm2_key_rsa module, which implements asymmetric TPM2 RSA key.
> The feature can be enabled with the CONFIG_ASYMMETRIC_TPM2_KEY_RSA_SUBTYPE 
> kconfig option. This feature allows the private key to be uploaded to
> the TPM2 for signing, and software can use the public key to verify
> the signatures.

Since barely v6.9 is out I wrote over night also tpm2_key_ecdsa i.e.
ECC/ECDSA based module :-)

It was a good idea. I realized e.g. actually documented in the API
fact that I should return -EBADMSG as legit undetected. Also found
a memory corruption bugs.

I renamed extract_pub to probe because that made me sort of realized
the role better too. Some of the code could later on put to up-level
struct tpm2_key but it is not a functional requirement.

I.e. top-level does raw parsing and then these modules check each
that if this is for them (e.g. ECDSA) then eat it. Otherwise, pass
over.

I did do some rudimentary testing and it seems to be quite good, and
my pattern seems to work. I.e. different modules for RSA and ECDSA
fit well how asymmetric keys are probed and allows to do as a sysadmin
appropriate configuration for the use case.

My biggest concern is undocumented parameters API in akcipher.

BR, Jarkko