[PATCH v2 6/6] x86/ima: define arch_get_ima_policy() for x86

Nayna Jain
2018-09-14T08:00:05Z

From: Eric Richter <erichte@linux.vnet.ibm.com>

This patch implements an example arch-specific IMA policy for x86 to
enable measurement and appraisal of any kernel image loaded for kexec,
when CONFIG_KEXEC_VERIFY_SIG is not enabled.

For systems with CONFIG_KEXEC_VERIFY_SIG enabled, only the measurement
rule is enabled, not the IMA-appraisal rule.

Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
- Removed the policy KEXEC_ORIG_KERNEL_CHECK which was defined to
disable the kexec_load syscall.
- arch_get_ima_policy() uses arch_ima_get_secureboot() to get secureboot
state
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
---
arch/x86/kernel/ima_arch.c | 16 ++++++++++++++++
include/linux/ima.h | 4 ++++
security/integrity/ima/Kconfig | 8 ++++++++
3 files changed, 28 insertions(+)

diff --git a/arch/x86/kernel/ima_arch.c b/arch/x86/kernel/ima_arch.c
index bb5a88d2b271..6615321b833c 100644
--- a/arch/x86/kernel/ima_arch.c
+++ b/arch/x86/kernel/ima_arch.c
@@ -15,3 +15,19 @@ bool arch_ima_get_secureboot(void)
else
return false;
}
+
+/* arch rules for audit and user mode */
+static const char * const sb_arch_rules[] = {
+#ifndef CONFIG_KEXEC_VERIFY_SIG
+ "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
+#endif /* CONFIG_KEXEC_VERIFY_SIG */
+ "measure func=KEXEC_KERNEL_CHECK",
+ NULL
+};
+
+const char * const *arch_get_ima_policy(void)
+{
+ if (arch_ima_get_secureboot())
+ return sb_arch_rules;
+ return NULL;
+}
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 350fa957f8a6..dabd3abdf671 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -39,10 +39,14 @@ static inline bool arch_ima_get_secureboot(void)
}
#endif

+#if defined(CONFIG_X86) && defined(CONFIG_IMA_ARCH_POLICY)
+extern const char * const *arch_get_ima_policy(void);
+#else
static inline const char * const *arch_get_ima_policy(void)
{
return NULL;
}
+#endif

#else
static inline int ima_bprm_check(struct linux_binprm *bprm)
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 13b446328dda..97609a76aa14 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -157,6 +157,14 @@ config IMA_APPRAISE
<http://linux-ima.sourceforge.net>
If unsure, say N.

+config IMA_ARCH_POLICY
+ bool "Enable loading an IMA architecture specific policy"
+ depends on KEXEC_VERIFY_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
+ default n
+ help
+ This option enables loading an IMA architecture specific policy
+ based on run time secure boot flags.
+
config IMA_APPRAISE_BUILD_POLICY
bool "IMA build time configured policy rules"
depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
--
2.13.6