On Mon, 2020-07-06 at 08:18 -0500, Tyler Hicks wrote: > On 2020-07-03 10:15:32, Mimi Zohar wrote: > > On Thu, 2020-07-02 at 17:16 -0500, Tyler Hicks wrote: > > > On 2020-06-30 19:07:29, Mimi Zohar wrote: > > > > On Fri, 2020-06-26 at 17:38 -0500, Tyler Hicks wrote: > > > > > Use ima_validate_rule() to ensure that the combination of a hook > > > > > function and the keyrings conditional is valid and that the keyrings > > > > > conditional is not specified without an explicit KEY_CHECK func > > > > > conditional. This is a code cleanup and has no user-facing change. > > > > > > > > > > Signed-off-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx> > > > > > --- > > > > > > > > > > * v2 > > > > > - Allowed IMA_DIGSIG_REQUIRED, IMA_PERMIT_DIRECTIO, > > > > > IMA_MODSIG_ALLOWED, and IMA_CHECK_BLACKLIST conditionals to be > > > > > present in the rule entry flags for non-buffer hook functions. > > > > > > > > > > security/integrity/ima/ima_policy.c | 13 +++++++++++-- > > > > > 1 file changed, 11 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c > > > > > index 8cdca2399d59..43d49ad958fb 100644 > > > > > --- a/security/integrity/ima/ima_policy.c > > > > > +++ b/security/integrity/ima/ima_policy.c > > > > > @@ -1000,6 +1000,15 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) > > > > > case KEXEC_KERNEL_CHECK: > > > > > case KEXEC_INITRAMFS_CHECK: > > > > > case POLICY_CHECK: > > > > > + if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC | > > > > > + IMA_UID | IMA_FOWNER | IMA_FSUUID | > > > > > + IMA_INMASK | IMA_EUID | IMA_PCR | > > > > > + IMA_FSNAME | IMA_DIGSIG_REQUIRED | > > > > > + IMA_PERMIT_DIRECTIO | > > > > > + IMA_MODSIG_ALLOWED | > > > > > + IMA_CHECK_BLACKLIST)) > > > > > > > > Other than KEYRINGS, this patch should continue to behave the same. > > > > However, this list gives the impressions that all of these flags are > > > > permitted on all of the above flags, which isn't true. > > > > > > > > For example, both IMA_MODSIG_ALLOWED & IMA_CHECK_BLACKLIST are limited > > > > to appended signatures, meaning KERNEL_CHECK and KEXEC_KERNEL_CHECK. > > > > > > Just to clarify, are both IMA_MODSIG_ALLOWED and IMA_CHECK_BLACKLIST > > > limited to KEXEC_KERNEL_CHECK, KEXEC_INITRAMFS_CHECK, and MODULE_CHECK? > > > That's what ima_hook_supports_modsig() suggests. > > > > Theoretically that is true, but I have no idea how you would append a > > signature to the kexec boot command line. The only users of appended > > signatures are currently kernel modules and the kexec'ed kernel image. > > The discrepancy was with KEXEC_INITRAMFS_CHECK, not KEXEC_CMDLINE. I now > see that there's no support for initramfs signature verification in the > kexec code so I'll assume that ima_hook_supports_modsig() is wrong and > limit IMA_MODSIG_ALLOWED and IMA_CHECK_BLACKLIST to the > KEXEC_KERNEL_CHECK and MODULE_CHECK actions, as you originally > suggested. My mistake. Yes, both the kexec kernel image and the initramfs read the respective file into memory and can be signed either with an imasig or modsig. Refer to kernel_read_file_from_fd(). Mimi
