On Fri, 2023-07-14 at 09:29 +0800, Coiby Xu wrote:
> On Tue, Jul 04, 2023 at 08:57:10AM -0400, Mimi Zohar wrote:
> >On Mon, 2023-07-03 at 19:54 +0800, Coiby Xu wrote:
> >> With the introduction of the .machine keyring for UEFI-based systems,
> >> users are able to add custom CAs keys via MOK. This allow users to sign
> >> their own IMA polices. For the sake of security, mandate signed IMA
> >> policy when UEFI secure boot is enabled.
> >>
> >> Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> >> Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
With commit 099f26f22f58 ("integrity: machine keyring CA
configuration") it is now possible to require signed IMA policies
without having to recompile the kernel. Please note this change might
affect existing users/tests.
> >> ---
> >> security/integrity/ima/ima_efi.c | 3 +++
> >> 1 file changed, 3 insertions(+)
> >>
> >> diff --git a/security/integrity/ima/ima_efi.c b/security/integrity/ima/ima_efi.c
> >> index 9db66fe310d4..bb2881759505 100644
> >> --- a/security/integrity/ima/ima_efi.c
> >> +++ b/security/integrity/ima/ima_efi.c
> >> @@ -58,6 +58,9 @@ static const char * const sb_arch_rules[] = {
> >> #if !IS_ENABLED(CONFIG_MODULE_SIG)
> >> "appraise func=MODULE_CHECK appraise_type=imasig",
> >> #endif
> >> +#if IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING) && IS_ENABLED(CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY)
> >> + "appraise func=POLICY_CHECK appraise_type=imasig",
> >> +#endif /* CONFIG_INTEGRITY_MACHINE_KEYRING && IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY */
> >> "measure func=MODULE_CHECK",
> >> NULL
> >> };
> >
> >Thanks, Coiby.
>
> You are welcome!
>
> >
> >Using IS_ENABLED() is not wrong, but unnecessary. IS_BUILTIN()
> >suffices.
>
> Thanks for the reminding! When I was going to apply this suggestion, I
> noticed ima_efi.c uses IS_ENABLED for all configuration items i.e.
> CONFIG_MODULE_SIG and CONFIG_KEXEC_SIG which are all of bool type. Would
> you like me to switch all IS_ENABLEs to IS_BUILTIN or still use
> IS_ENABLED? While IS_BUILTIN is exclusively for bool type, it's not as
> intuitive as IS_ENABLED. So it's not easy for me to make a choice.
Sure, for consistency with the other rules IS_ENABLED is fine.
thanks,
Mimi
