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. /Jarkko
