linux-kernel - Re: Conflict with Mickaël Salaün's blacklist patches [was [PATCH v5 0/4] Add EFI_CERT_X509

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Message-ID: <dc6a4524-3935-fda6-40a8-cebf80942cdf@digikod.net>
Date:   Fri, 5 Feb 2021 11:27:02 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     David Howells <dhowells@...hat.com>, dwmw2@...radead.org,
        Jarkko Sakkinen <jarkko@...nel.org>,
        James.Bottomley@...senPartnership.com, masahiroy@...nel.org,
        michal.lkml@...kovi.net, jmorris@...ei.org, serge@...lyn.com,
        ardb@...nel.org, Mimi Zohar <zohar@...ux.ibm.com>,
        lszubowi@...hat.com, javierm@...hat.com, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Tyler Hicks <tyhicks@...ux.microsoft.com>
Subject: Re: Conflict with Mickaël Salaün's blacklist patches [was [PATCH v5 0/4] Add EFI_CERT_X509_GUID support for dbx/mokx entries]


On 05/02/2021 01:24, Eric Snowberg wrote:
> 
>> On Feb 4, 2021, at 1:26 AM, Mickaël Salaün <mic@...ikod.net> wrote:
>>
>>
>> On 04/02/2021 04:53, Eric Snowberg wrote:
>>>
>>>> On Feb 3, 2021, at 11:49 AM, Mickaël Salaün <mic@...ikod.net> wrote:
>>>>
>>>> This looks good to me, and it still works for my use case. Eric's
>>>> patchset only looks for asymmetric keys in the blacklist keyring, so
>>>> even if we use the same keyring we don't look for the same key types. My
>>>> patchset only allows blacklist keys (i.e. hashes, not asymmetric keys)
>>>> to be added by user space (if authenticated), but because Eric's
>>>> asymmetric keys are loaded with KEY_ALLOC_BYPASS_RESTRICTION, it should
>>>> be OK for his use case.  There should be no interference between the two
>>>> new features, but I find it a bit confusing to have such distinct use of
>>>> keys from the same keyring depending on their type.
>>>
>>> I agree, it is a bit confusing.  What is the thought of having a dbx 
>>> keyring, similar to how the platform keyring works?
>>>
>>> https://www.spinics.net/lists/linux-security-module/msg40262.html
>>>
>>>
>>>> On 03/02/2021 17:26, David Howells wrote:
>>>>>
>>>>> Eric Snowberg <eric.snowberg@...cle.com> wrote:
>>>>>
>>>>>> This is the fifth patch series for adding support for 
>>>>>> EFI_CERT_X509_GUID entries [1].  It has been expanded to not only include
>>>>>> dbx entries but also entries in the mokx.  Additionally my series to
>>>>>> preload these certificate [2] has also been included.
>>>>>
>>>>> Okay, I've tentatively applied this to my keys-next branch.  However, it
>>>>> conflicts minorly with Mickaël Salaün's patches that I've previously merged on
>>>>> the same branch.  Can you have a look at the merge commit
>>>>>
>>>>> 	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?h=keys-next&id=fdbbe7ceeb95090d09c33ce0497e0394c82aa33d
>>>>>
>>>>> 	(the top patch of my keys-next branch)
>>>>>
>>>>> to see if that is okay by both of you?  If so, can you give it a whirl?
>>>
>>>
>>> I’m seeing a build error within blacklist_hashes_checked with
>>> one of my configs.
>>>
>>> The config is as follows:
>>>
>>> $ grep CONFIG_SYSTEM_BLACKLIST_HASH_LIST .config
>>> CONFIG_SYSTEM_BLACKLIST_HASH_LIST=“revocation_list"
>>>
>>> $ cat certs/revocation_list
>>> "tbs:1e125ea4f38acb7b29b0c495fd8e7602c2c3353b913811a9da3a2fb505c08a32”
>>>
>>> make[1]: *** No rule to make target 'revocation_list', needed by 'certs/blacklist_hashes_checked'.  Stop.
>>
>> It requires an absolute path.
> 
> Ok, if I use an absolute path now with CONFIG_SYSTEM_BLACKLIST_HASH_LIST 
> it works.
> 
>> This is to align with other variables
>> using the config_filename macro: CONFIG_SYSTEM_TRUSTED_KEYS,
>> CONFIG_MODULE_SIG_KEY and now CONFIG_SYSTEM_REVOCATION_KEYS.
> 
> I just did a quick test with CONFIG_SYSTEM_TRUSTED_KEYS. It looks like we 
> can use either a relative or absolute path with CONFIG_SYSTEM_TRUSTED_KEYS. 
> Shouldn’t this be consistent?

CONFIG_SYSTEM_TRUSTED_KEYS (and similar config) works with relative path
to $(srctree) not $(srctree)/certs as in your example.

We can make CONFIG_SYSTEM_BLACKLIST_HASH_LIST works with $(srctree) with
this patch:

diff --git a/certs/Makefile b/certs/Makefile
index eb45407ff282..92a233eaa926 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -14,6 +14,8 @@ $(eval $(call config_filename,SYSTEM_BLACKLIST_HASH_LIST))

 $(obj)/blacklist_hashes.o: $(obj)/blacklist_hashes_checked

+CFLAGS_blacklist_hashes.o += -I$(srctree)
+
 targets += blacklist_hashes_checked


> 
>> Cf. https://lore.kernel.org/lkml/1221725.1607515111@warthog.procyon.org.uk/
>>
>> We may want to patch scripts/kconfig/streamline_config.pl for both
>> CONFIG_SYSTEM_REVOCATION_KEYS and CONFIG_SYSTEM_BLACKLIST_HASH_LIST, to
>> warn user (and exit with an error) if such files are not found.
>