RE: One question about trusted key of keyring in Linux kernel.

[Zhao, Shirley]

Hi, Mimi, 

My test environment is Ubuntu 18.04.3, kernel version is 5.0.0-36-generic. 
$ cat /proc/version
Linux version 5.0.0-36-generic (buildd@lgw01-amd64-060) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #39~18.04.1-Ubuntu SMP Tue Nov 12 11:09:50 UTC 2019
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.3 LTS
Release:        18.04
Codename:       bionic

It is TPM2.0, dTPM. 

And I didnât run it on other version. 

It has no relationship with TPM command, it is just used to help find the fail reason. 
My question is how to load a trusted key which is sealed with PCR policy correctly after reboot.
That is better if there is some example about how to use "policydigest", "policyhandle" to seal/unseal a trusted key. 

Thanks. 

- Shirley 



-----Original Message-----
From: Mimi Zohar <zohar@xxxxxxxxxxxxx> 
Sent: Wednesday, November 27, 2019 11:39 PM
To: Zhao, Shirley <shirley.zhao@xxxxxxxxx>; James Bottomley <jejb@xxxxxxxxxxxxx>; Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>; Jonathan Corbet <corbet@xxxxxxx>
Cc: linux-integrity@xxxxxxxxxxxxxxx; keyrings@xxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; 'Mauro Carvalho Chehab' <mchehab+samsung@xxxxxxxxxx>; Zhu, Bing <bing.zhu@xxxxxxxxx>; Chen, Luhai <luhai.chen@xxxxxxxxx>
Subject: Re: One question about trusted key of keyring in Linux kernel.

Hi Shirley,

On Wed, 2019-11-27 at 02:46 +0000, Zhao, Shirley wrote:
> Hi, Mimi,
> 
> Answer your two questions:
> 
> 1. Yes, I have verified trusted key works well without PCR policy 
> protection as below:
> $ keyctl add trusted kmk "new 32 keyhandle=0x81000001" @u
> 1055240928
> $ keyctl list @u
> 1 keys in keyring:
> 1055240928: --alswrv     0     0 trusted: kmk
> $ keyctl pipe 1055240928 > kmk.blob
> $ cat kmk.blob
> 007f0020ff808bd8b7239194e89aac6a95b4d210114742c20afa33493f002dffd068
> 5d510010c12d7ad51eb83d6d93895de066bf3d39718cc503adb4802cb087b88b2fff
> 4b040fe3a2be6a3f87c6749d087c9fb6e8734cb23f438d64087581a13bc83d5dc3b0
> 26e77a894ece6620d0eb85df6449ff3c609fd77d5f0caf79b4535b002e0008000b00
> 0000400000001000209a5b00b0d558fcf9e8c029522715e6b5906366eaec5f34367b
> 8ab16c0fb9009a0073000000000020e3b0c44298fc1c149afbf4c8996fb92427ae41
> e4649b934ca495991b7852b85501000b0022000bdcdb694e102e13a0fba5111081cb
> 6cf616c118d404936cac3e84db24c71e47d50022000b04b5db1aa52635dfb242e76f
> 6bde8e2176ae48fc682946c6c76d96f608079d1f0000002036b6fcca8206c7f722de
> 85821d7ecb4785976fdd642bc7538505a2a818c8a23880214000000100202aedde45
> 08f548d108193ec8fe166a7befde19113fe727ae2b29901bdece96e5
> $ keyctl clear @u
> $ keyctl list @u
> keyring is empty
> $ keyctl add trusted kmk "load `cat kmk.blob` keyhandle=0x81000001"
> @u
> 1022963731
> $ keyctl print 1022963731
> 007f0020ff808bd8b7239194e89aac6a95b4d210114742c20afa33493f002dffd068
> 5d510010c12d7ad51eb83d6d93895de066bf3d39718cc503adb4802cb087b88b2fff
> 4b040fe3a2be6a3f87c6749d087c9fb6e8734cb23f438d64087581a13bc83d5dc3b0
> 26e77a894ece6620d0eb85df6449ff3c609fd77d5f0caf79b4535b002e0008000b00
> 0000400000001000209a5b00b0d558fcf9e8c029522715e6b5906366eaec5f34367b
> 8ab16c0fb9009a0073000000000020e3b0c44298fc1c149afbf4c8996fb92427ae41
> e4649b934ca495991b7852b85501000b0022000bdcdb694e102e13a0fba5111081cb
> 6cf616c118d404936cac3e84db24c71e47d50022000b04b5db1aa52635dfb242e76f
> 6bde8e2176ae48fc682946c6c76d96f608079d1f0000002036b6fcca8206c7f722de
> 85821d7ecb4785976fdd642bc7538505a2a818c8a23880214000000100202aedde45
> 08f548d108193ec8fe166a7befde19113fe727ae2b29901bdece96e5
> 
> 2. The following kernel file is related with this problem. 
> /security/keys/keyctl.c /security/keys/key.c 
> /security/keys/trusted-keys/trusted_tpm1.c
> /security/keys/trusted-keys/trusted_tpm2.c
> 
> To load the PCR policy protection trusted key, the call stack is:
> SYSCALL_DEFINE5(add_key,...) --> key_create_or_update() -->
> __key_instantiate_and_link() -->  trusted_instantiate() -->
> tpm2_unseal_trusted() --> tpm2_unseal_cmd().
> 
> Check dmesg, there will be error:
> [73336.351596] trusted_key: key_unseal failed (-1)

Like the other kernel mailing lists, please bottom post. ÂWhen reporting a problem, please include the kernel version and other relevant details. ÂFor example, the TPM version and type (eg. hardware vendor, software TPM, etc). ÂPlease indicate if this is a new problem and which kernel release it first start happening?

I have no experience with the tpm2_ commands, ÂI suggest trying to extend a single measurement to a PCR and sealing to that value.

Mimi