powerpc/ima: Define trusted boot policy

This patch defines an arch-specific trusted boot only policy and a
combined secure and trusted boot policy.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1572492694-6520-5-git-send-email-zohar@linux.ibm.com

diff --git a/arch/powerpc/kernel/ima_arch.c b/arch/powerpc/kernel/ima_arch.c
index d88913dc0da7d94a12a15a1c2ab82184c1cca481..0ef5956c9753e89becfc7040265b1c77a73bbfcb 100644 (file)
--- a/arch/powerpc/kernel/ima_arch.c
+++ b/arch/powerpc/kernel/ima_arch.c
@@ -30,6 +30,32 @@ static const char *const secure_rules[] = {
        NULL
 };
 
+/*
+ * The "trusted_rules" are enabled only on "trustedboot" enabled systems.
+ * These rules add the kexec kernel image and kernel modules file hashes to
+ * the IMA measurement list.
+ */
+static const char *const trusted_rules[] = {
+       "measure func=KEXEC_KERNEL_CHECK",
+       "measure func=MODULE_CHECK",
+       NULL
+};
+
+/*
+ * The "secure_and_trusted_rules" contains rules for both the secure boot and
+ * trusted boot. The "template=ima-modsig" option includes the appended
+ * signature, when available, in the IMA measurement list.
+ */
+static const char *const secure_and_trusted_rules[] = {
+       "measure func=KEXEC_KERNEL_CHECK template=ima-modsig",
+       "measure func=MODULE_CHECK template=ima-modsig",
+       "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
+#ifndef CONFIG_MODULE_SIG_FORCE
+       "appraise func=MODULE_CHECK appraise_type=imasig|modsig",
+#endif
+       NULL
+};
+
 /*
  * Returns the relevant IMA arch-specific policies based on the system secure
  * boot state.
@@ -37,7 +63,12 @@ static const char *const secure_rules[] = {
 const char *const *arch_get_ima_policy(void)
 {
        if (is_ppc_secureboot_enabled())
-               return secure_rules;
+               if (is_ppc_trustedboot_enabled())
+                       return secure_and_trusted_rules;
+               else
+                       return secure_rules;
+       else if (is_ppc_trustedboot_enabled())
+               return trusted_rules;
 
        return NULL;
 }