On Sat, Jan 15, 2022 at 07:12:35PM +0000, Eric Snowberg wrote: > > > > On Jan 15, 2022, at 10:11 AM, Jarkko Sakkinen <jarkko@xxxxxxxxxx> wrote: > > > > On Wed, Jan 12, 2022 at 02:41:47PM -0500, Mimi Zohar wrote: > >> On Tue, 2022-01-11 at 20:14 -0500, Mimi Zohar wrote: > >>> On Tue, 2022-01-11 at 21:26 +0000, Eric Snowberg wrote: > >>>> > >>>>> On Jan 11, 2022, at 11:16 AM, Mimi Zohar <zohar@xxxxxxxxxxxxx> wrote: > >>>>> > >>>>> On Mon, 2022-01-10 at 23:25 +0000, Eric Snowberg wrote: > >>>>>>> Jarkko, my concern is that once this version of the patch set is > >>>>>>> upstreamed, would limiting which keys may be loaded onto the .machine > >>>>>>> keyring be considered a regression? > >>>>>> > >>>>>> > >>>>>> Currently certificates built into the kernel do not have a CA restriction on them. > >>>>>> IMA will trust anything in this keyring even if the CA bit is not set. While it would > >>>>>> be advisable for a kernel to be built with a CA, nothing currently enforces it. > >>>>>> > >>>>>> My thinking for the dropped CA restriction patches was to introduce a new Kconfig. > >>>>>> This Kconfig would do the CA enforcement on the machine keyring. However if the > >>>>>> Kconfig option was not set for enforcement, it would work as it does in this series, > >>>>>> plus it would allow IMA to work with non-CA keys. This would be done by removing > >>>>>> the restriction placed in this patch. Let me know your thoughts on whether this would > >>>>>> be an appropriate solution. I believe this would get around what you are identifying as > >>>>>> a possible regression. > >>>>> > >>>>> True the problem currently exists with the builtin keys, but there's a > >>>>> major difference between trusting the builtin keys and those being > >>>>> loading via MOK. This is an integrity gap that needs to be closed and > >>>>> shouldn't be expanded to keys on the .machine keyring. > >>>>> > >>>>> "plus it would allow IMA to work with non-CA keys" is unacceptable. > >>>> > >>>> Ok, I’ll leave that part out. Could you clarify the wording I should include in the future > >>>> cover letter, which adds IMA support, on why it is unacceptable for the end-user to > >>>> make this decision? > >>> > >>> The Kconfig IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY > >>> "help" is very clear: > >> > >> [Reposting the text due to email formatting issues.] > >> > >> help > >> Keys may be added to the IMA or IMA blacklist keyrings, if the > >> key is validly signed by a CA cert in the system built-in or > >> secondary trusted keyrings. > >> > >> Intermediate keys between those the kernel has compiled in and the > >> IMA keys to be added may be added to the system secondary keyring, > >> provided they are validly signed by a key already resident in the > >> built-in or secondary trusted keyrings. > >> > >> > >> The first paragraph requires "validly signed by a CA cert in the system > >> built-in or secondary trusted keyrings" for keys to be loaded onto the > >> IMA keyring. This Kconfig is limited to just the builtin and secondary > >> keyrings. Changing this silently to include the ".machine" keyring > >> introduces integrity risks that previously did not exist. A new IMA > >> Kconfig needs to be defined to allow all three keyrings - builtin, > >> machine, and secondary. > >> > >> The second paragraph implies that only CA and intermediate CA keys are > >> on secondary keyring, or as in our case the ".machine" keyring linked > >> to the secondary keyring. > >> > >> Mimi > >> > > I have also now test environment for this patch set but if there are > > any possible changes, I'm waiting for a new version, as it is anyway > > for 5.18 cycle earliest. > > Other than the two sentence changes, I have not seen anything identified > code wise requiring a change. If you’d like me to respin a v10 with the sentence > changes let me know. Or if you want to remove the ima reference, that works > too. Just let me know how you want to handle this. Thanks. I'm basically waiting also Mimi to test this as I do not have IMA test environment. >From my side: Tested-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> /Jarkko
