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From: Eric Snowberg <eric.snowberg@oracle.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: keyrings@vger.kernel.org,
	linux-integrity <linux-integrity@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S . Miller" <davem@davemloft.net>,
	Jarkko Sakkinen <jarkko@kernel.org>,
	James Morris <jmorris@namei.org>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	keescook@chromium.org, gregkh@linuxfoundation.org,
	torvalds@linux-foundation.org, scott.branden@broadcom.com,
	weiyongjun1@huawei.com, nayna@linux.ibm.com, ebiggers@google.com,
	ardb@kernel.org,
	Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
	lszubowi@redhat.com, linux-kernel@vger.kernel.org,
	linux-crypto@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	James.Bottomley@HansenPartnership.com, pjones@redhat.com,
	glin@suse.com, "konrad.wilk@oracle.com" <konrad.wilk@oracle.com>
Subject: Re: [PATCH RFC v2 10/12] KEYS: link system_trusted_keys to mok_trusted_keys
Date: Fri, 6 Aug 2021 09:00:20 -0600	[thread overview]
Message-ID: <21CB8F51-9066-4095-9C6E-428FF9E86443@oracle.com> (raw)
In-Reply-To: <d85bfe88bb4abd06e47a36743f53d0610da0a259.camel@linux.ibm.com>


> On Aug 5, 2021, at 9:19 PM, Mimi Zohar <zohar@linux.ibm.com> wrote:
> 
> On Thu, 2021-08-05 at 19:29 -0600, Eric Snowberg wrote:
> 
>>> From the thread discussion on 00/12:
>>> 
>>> Only the builtin keys should ever be on the builtin keyring.  The
>>> builtin keyring would need to be linked to the mok keyring.  But in the
>>> secondary keyring case, the mok keyring would be linked to the
>>> secondary keyring, similar to how the builtin keyring is linked to the
>>> secondary keyring.
>>> 
>>>       if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
>>>               panic("Can't link trusted keyrings\n");
>> 
>> 
>> This part is confusing me though.
>> 
>> Here are some of the tests I’m performing with the current series:
>> 
>> Initial setup:
>> Create and enroll my own key into the MOK.
>> Sign a kernel, kernel module and IMA key with my new CA key.
>> Boot with lockdown enabled (to enforce sig validation).
>> 
>> Kernel built with CONFIG_SECONDARY_TRUSTED_KEYRING=y
>> 
>> $ keyctl show %:.secondary_trusted_keys
>> Keyring
>> 530463486 ---lswrv      0     0  keyring: .secondary_trusted_keys
>> 411466727 ---lswrv      0     0   \_ keyring: .builtin_trusted_keys
>> 979167715 ---lswrv      0     0   |   \_ asymmetric: Build time autogenerated kernel key: 07a56e29cfa1e21379aff2c522efff7d1963202a
>> 534573591 ---lswrv      0     0   |   \_ asymmetric: Oracle-CA: Oracle certificate signing key: aeefb4bfde095cacaabff81dd266974b1b4e23b8
>> 968109018 ---lswrv      0     0   \_ keyring: .mok
>> 857795115 ---lswrv      0     0       \_ asymmetric: Erics-CA: UEK signing key: 9bfa6860483aa46bd83f7fa1289d9fc35799e93b
>> 
>> With this setup I can:
>> * load a kernel module signed with my CA key
>> * run "kexec -ls" with the kernel signed with my CA key
>> * run "kexec -ls" with a kernel signed by a key in the platform keyring
>> * load another key into the secondary trusted keyring that is signed by my CA key
>> * load a key into the ima keyring, signed by my CA key
>> 
>> Kernel built without CONFIG_SECONDARY_TRUSTED_KEYRING defined
>> 
>> $ keyctl show %:.builtin_trusted_keys
>> Keyring
>> 812785375 ---lswrv      0     0  keyring: .builtin_trusted_keys
>> 455418681 ---lswrv      0     0   \_ keyring: .mok
>> 910809006 ---lswrv      0     0   |   \_ asymmetric: Erics-CA: UEK signing key: 9bfa6860483aa46bd83f7fa1289d9fc35799e93b
>> 115345009 ---lswrv      0     0   \_ asymmetric: Oracle-CA: Oracle certificate signing key: aeefb4bfde095cacaabff81dd266974b1b4e23b8
>> 513131506 ---lswrv      0     0   \_ asymmetric: Build time autogenerated kernel key: 22353509f203b55b84f15d0aadeddc134b646185
>> 
>> With this setup I can:
>> * load a kernel module signed with my CA key
>> * run "kexec -ls" with the kernel signed with my CA key
>> * run "kexec -ls" with a kernel signed by a key in the platform keyring
>> * load a key into the ima keyring, signed by my CA key
>> 
>> So why would the linking need to be switched?  Is there a test I’m
>> missing?  Thanks.
> 
> It's a question of semantics.  The builtin keyring name is self
> describing.  It should only contain the keys compiled into the kernel
> or inserted post build into the reserved memory.  Not only the kernel
> uses the builtin keyring, but userspace may as well[1].  Other users of
> the builtin keyring might not want to trust the mok keyring as well.

Should this feature only work with kernels built with 
CONFIG_SECONDARY_TRUSTED_KEYRING defined?  If so, I could drop support in 
the next version for kernels built without it.  


  reply	other threads:[~2021-08-06 15:01 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 17:13 [PATCH RFC v2 00/12] Enroll kernel keys thru MOK Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 01/12] integrity: Introduce a Linux keyring for the Machine Owner Key (MOK) Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 02/12] KEYS: CA link restriction Eric Snowberg
2021-08-05 14:00   ` Mimi Zohar
2021-07-26 17:13 ` [PATCH RFC v2 03/12] integrity: Trust MOK keys if MokListTrustedRT found Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 04/12] integrity: add add_to_mok_keyring Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 05/12] integrity: restrict INTEGRITY_KEYRING_MOK to restrict_link_by_system_trusted_or_ca Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 06/12] integrity: accessor function to get trust_moklist Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 07/12] integrity: add new keyring handler for mok keys Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 08/12] integrity: Suppress error message for keys added to the mok keyring Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 09/12] KEYS: add a reference to " Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 10/12] KEYS: link system_trusted_keys to mok_trusted_keys Eric Snowberg
2021-08-05 13:58   ` Mimi Zohar
2021-08-06  1:29     ` Eric Snowberg
2021-08-06  3:19       ` Mimi Zohar
2021-08-06 15:00         ` Eric Snowberg [this message]
2021-08-06 15:18           ` Mimi Zohar
2021-08-06 21:20             ` Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 11/12] integrity: Do not allow mok keyring updates following init Eric Snowberg
2021-07-26 17:13 ` [PATCH RFC v2 12/12] integrity: store reference to mok keyring Eric Snowberg
2021-08-03 17:01 ` [PATCH RFC v2 00/12] Enroll kernel keys thru MOK Mimi Zohar
2021-08-03 19:52   ` Eric Snowberg
2021-08-04  1:14     ` Mimi Zohar
2021-08-04  2:56       ` Eric Snowberg
2021-08-05 13:58         ` Mimi Zohar

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