[PATCH] ima: add a new CONFIG for loading arch-specific policies

[Nayna Jain <nayna@linux.ibm.com>]

Every time a new architecture defines the IMA architecture specific
functions - arch_ima_get_secureboot() and arch_ima_get_policy(), the IMA
include file needs to be updated. To avoid this "noise", this patch
defines a new IMA Kconfig IMA_SECURE_AND_OR_TRUSTED_BOOT option, allowing
the different architectures to select it.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Philipp Rudo <prudo@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/Kconfig           | 2 +-
 arch/s390/Kconfig              | 1 +
 arch/x86/Kconfig               | 1 +
 include/linux/ima.h            | 3 +--
 security/integrity/ima/Kconfig | 9 +++++++++
 5 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 497b7d0b2d7e..b8ce1b995633 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -246,6 +246,7 @@ config PPC
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select VIRT_TO_BUS			if !PPC64
+	select IMA_SECURE_AND_OR_TRUSTED_BOOT	if PPC_SECURE_BOOT
 	#
 	# Please keep this list sorted alphabetically.
 	#
@@ -978,7 +979,6 @@ 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/s390/Kconfig b/arch/s390/Kconfig
index 8abe77536d9d..90ff3633ade6 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -195,6 +195,7 @@ config S390
 	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
 	select SWIOTLB
 	select GENERIC_ALLOCATOR
+	select IMA_SECURE_AND_OR_TRUSTED_BOOT
 
 
 config SCHED_OMIT_FRAME_POINTER
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index beea77046f9b..cafa66313fe2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -230,6 +230,7 @@ config X86
 	select VIRT_TO_BUS
 	select X86_FEATURE_NAMES		if PROC_FS
 	select PROC_PID_ARCH_STATUS		if PROC_FS
+	select IMA_SECURE_AND_OR_TRUSTED_BOOT	if EFI
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 1659217e9b60..aefe758f4466 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -30,8 +30,7 @@ extern void ima_kexec_cmdline(const void *buf, int size);
 extern void ima_add_kexec_buffer(struct kimage *image);
 #endif
 
-#if (defined(CONFIG_X86) && defined(CONFIG_EFI)) || defined(CONFIG_S390) \
-	|| defined(CONFIG_PPC_SECURE_BOOT)
+#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
 extern bool arch_ima_get_secureboot(void);
 extern const char * const *arch_get_ima_policy(void);
 #else
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 3f3ee4e2eb0d..d17972aa413a 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -327,3 +327,12 @@ config IMA_QUEUE_EARLY_BOOT_KEYS
 	depends on IMA_MEASURE_ASYMMETRIC_KEYS
 	depends on SYSTEM_TRUSTED_KEYRING
 	default y
+
+config IMA_SECURE_AND_OR_TRUSTED_BOOT
+	bool
+	depends on IMA
+	depends on IMA_ARCH_POLICY
+	default n
+	help
+	   This option is selected by architectures to enable secure and/or
+	   trusted boot based on IMA runtime policies.
-- 
2.18.1