Made an ZFS root pool auto-unlock, please give review of method
by Garrett Fields
Back in the end of July, I wrote a message on this discussion list titled
"PCR Policy enforcement when using nvram". In that, I asked for a way to
have both a PCR check AND a password lock an nvram range (not an OR). I
really appreciated everyone's help, especially William Roberts, who gave
some sample code of using a session to accomplish this goal.
Now that Ubuntu has updated its repositories for the upcoming 20.04 LTS
release and included TPM-tools v4.x, I figured it was time to take another
look.
My goal is to provide a method to auto-unlock a ZFS encrypted root
filesystem. Currently, ZFS allows for unlocking via a prompt or file
containing a raw, hex, or passphrase values. The mechanisms are already
inplace to prompt on startup.
So far I have just done a proof of concept. It probably loads of bad code
and tons of polish needed:
https://github.com/ghfields/zfs/compare/master...ghfields:tpm2-autounlock
I forked the zfs project, expanded the its initramfs hooks to include the
required tpm2-tools binaries, and added another stanza to init script's
decrypting section. I also created a pair of scripts that configures the
system and tests readback.
The nvram index and the PCRs used are stored/read from the zfs filesystem
properties. I used the filesytem's GUID as the required password as
another check to verify the NVRAM range was intended for that filesystem.
I also intend to issue an nvreadlock to prevent snooping once the key is
used.
I'd be interested in a critique of the method overall I expect there ways
to make this more secure. With enough effort, one could issue a
break=premount on the kernel line and manually extract the password from
the TPM. Any way to tighten that up?
I'm a total novice at TPM in general, but am completely open to advise and
guidance.
Thanks,
Garrett Fields
3 months
Question about how to get session handle when create policy
by Zhao, Shirley
Hello,
I want to get the session handle when creating policy, how to do it?
For example,
# tpm2_createpolicy --policy-pcr --pcr-list sha256:7 --policy pcr.policy --policy-session
2781c435e602b97eef2a95333b72d085a393907cf32b9f825febe37b1af54820
I use tpm2_createpolicy to create the policy, and start a policy session of type TPM_SE_POLICY.
The policy digest is returned, but I can't get the session handle.
So how to get the session handle?
Thanks.
* Shirley
5 months, 2 weeks
[RC] tpm2-tools: 4.1.1-RC0
by Roberts, William C
Hello,
I'd like to announce that tpm2-tools release 4.1.1-RC0 is now available:
https://github.com/tpm2-software/tpm2-tools/releases/tag/4.1.1-RC0
The changes are below:
* tpm2_certify: Fix output of attestation data including size field. Now outputs just bytes.
* tpm2_certifycreation: Fix tool to match manpage where the code had the -C and -c options reversed.
* tpm2_gettime: Fix output of attestation data including size field. Now outputs just bytes.
* tpm2_nvcertify: Fix output of attestation data including size field. Now outputs just bytes.
* tpm2_nvreadpublic: add name hash output.
* tpm2_import: Support object policies when importing raw key material.
* Fix overflow in pcrs.h where sizeof() was used instead of ARRAY_LEN().
* build:
- Fix compilation inssue: lib/tpm2_hash.c:17:19: note: 'left' was declared here.
* man:
- Fix manpage examples that have "sha" instead of "sha1"
- tpm2_shutdown manpage was missing, add it to build.
I'd like to point out these 3 changes:
* tpm2_certify: Fix output of attestation data including size field. Now outputs just bytes.
* tpm2_gettime: Fix output of attestation data including size field. Now outputs just bytes.
* tpm2_nvcertify: Fix output of attestation data including size field. Now outputs just bytes.
We had a bug where we outputting the structure rather than just the signature bytes,
*so there is a format change on this*. We considered this a bug, and since the on-disk
format is likely not long lived (like a key blob would be), we didn't do a major or minor
version bump, just a patch level bump. Please let me know if this is a problem for you.
Bill
5 months, 2 weeks
tpm2_create signature verification fails due to "RSA_padding_check_PKCS_type1:invalid padding"
by Niklas Andersson
openssl can not verify plain signature (256 bytes) from tpm2_certify due to
bad padding.
*This should work (verification of signature from tpm2_certifycreation
works fine):*
openssl dgst -verify ../AIKOpaque.der -keyform der -sha1 -signature
Signature KeyAttest.bin
Verification Failure
*....examine:*
openssl rsautl -verify -inkey ../AIKOpaque.der -in Signature -pubin
-keyform der -pkcs > decrypted.bin
RSA operation error
140654247387584:error:0407008A:rsa
routines:R*SA_padding_check_PKCS1_type_1:invalid
padding:../crypto/rsa/rsa_pk1.c:67:*
140654247387584:error:04067072:rsa routines:rsa_ossl_public_decrypt:padding
check failed:../crypto/rsa/rsa_ossl.c:582:
*..Same operation on a plain signature from tpm2_certifycreation works:*
openssl rsautl -verify -inkey ../AIKOpaque.der -in
../IdBinding.EXTRACTED_TPMT_SIGNATURE -pubin -keyform der > decrypted.bin
dumpasn1 decrypted.bin
0 33: SEQUENCE {
2 9: SEQUENCE {
4 5: OBJECT IDENTIFIER sha1 (1 3 14 3 2 26)
11 0: NULL
: }
13 20: OCTET STRING 2D A1 D1 30 3A D2 FD 68 A1 5A 2F 9B 8B C1 1E DB 36
A7 7C D4
: }
So. It looks like a bug in tpm2_certify.
tool="tpm2_certify" version="4.1" tctis="libtss2-tctildr"
tcti-default=tcti-device
tpm2-tss 2.3.2-rc0
Regards,
Niklas
5 months, 3 weeks
tpm2-pcs11: Release 1.0-RC0
by Roberts, William C
Hello,
I'd like to announce the first release candidate for tpm2-pkcs11:
https://github.com/tpm2-software/tpm2-pkcs11/releases/tag/1.0-RC0
Well there is still a lot of features to add and bugs to address, this provides a great base to work
from and stabilizes the database. Having the database finally stable means that objects generated
will continue to work as we advance forward with development.
During the RC process we will only address bugs critical to the release, other issues, like needed features
will be worked on in subsequent releases.
Thanks,
Bill
5 months, 3 weeks
