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authorNayna Jain <nayna@linux.ibm.com>2019-10-30 23:31:27 -0400
committerMichael Ellerman <mpe@ellerman.id.au>2019-11-12 12:25:49 +1100
commit4238fad366a660cbc6499ca1ea4be42bd4d1ac5b (patch)
treeddfe3283dacee87a13c8191073b86d2b990c2a01 /arch/powerpc
parent1a8916ee3ac29054322cdac687d36e1b5894d272 (diff)
downloadlinux-4238fad366a660cbc6499ca1ea4be42bd4d1ac5b.tar.bz2
powerpc/ima: Add support to initialize ima policy rules
PowerNV systems use a Linux-based bootloader, which rely on the IMA subsystem to enforce different secure boot modes. Since the verification policy may differ based on the secure boot mode of the system, the policies must be defined at runtime. This patch implements arch-specific support to define IMA policy rules based on the runtime secure boot mode of the system. This patch provides arch-specific IMA policies if PPC_SECURE_BOOT config is enabled. 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/1572492694-6520-3-git-send-email-zohar@linux.ibm.com
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/Kconfig1
-rw-r--r--arch/powerpc/kernel/Makefile2
-rw-r--r--arch/powerpc/kernel/ima_arch.c43
3 files changed, 45 insertions, 1 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 56ea0019b616..c795039bdc73 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -938,6 +938,7 @@ config PPC_SECURE_BOOT
prompt "Enable secure boot support"
bool
depends on PPC_POWERNV
+ depends on IMA_ARCH_POLICY
help
Systems with firmware secure boot enabled need to define security
policies to extend secure boot to the OS. This config allows a user
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e2a54fa240ac..e8eb2955b7d5 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -161,7 +161,7 @@ ifneq ($(CONFIG_PPC_POWERNV)$(CONFIG_PPC_SVM),)
obj-y += ucall.o
endif
-obj-$(CONFIG_PPC_SECURE_BOOT) += secure_boot.o
+obj-$(CONFIG_PPC_SECURE_BOOT) += secure_boot.o ima_arch.o
# Disable GCOV, KCOV & sanitizers in odd or sensitive code
GCOV_PROFILE_prom_init.o := n
diff --git a/arch/powerpc/kernel/ima_arch.c b/arch/powerpc/kernel/ima_arch.c
new file mode 100644
index 000000000000..d88913dc0da7
--- /dev/null
+++ b/arch/powerpc/kernel/ima_arch.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain
+ */
+
+#include <linux/ima.h>
+#include <asm/secure_boot.h>
+
+bool arch_ima_get_secureboot(void)
+{
+ return is_ppc_secureboot_enabled();
+}
+
+/*
+ * The "secure_rules" are enabled only on "secureboot" enabled systems.
+ * These rules verify the file signatures against known good values.
+ * The "appraise_type=imasig|modsig" option allows the known good signature
+ * to be stored as an xattr or as an appended signature.
+ *
+ * To avoid duplicate signature verification as much as possible, the IMA
+ * policy rule for module appraisal is added only if CONFIG_MODULE_SIG_FORCE
+ * is not enabled.
+ */
+static const char *const secure_rules[] = {
+ "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.
+ */
+const char *const *arch_get_ima_policy(void)
+{
+ if (is_ppc_secureboot_enabled())
+ return secure_rules;
+
+ return NULL;
+}