Commit 311aa6aa authored Jul 13, 2020 by Bruno Meneguele Committed by Mimi Zohar Jul 20, 2020

ima: move APPRAISE_BOOTPARAM dependency on ARCH_POLICY to runtime



The IMA_APPRAISE_BOOTPARAM config allows enabling different "ima_appraise="
modes - log, fix, enforce - at run time, but not when IMA architecture
specific policies are enabled.  This prevents properly labeling the
filesystem on systems where secure boot is supported, but not enabled on the
platform.  Only when secure boot is actually enabled should these IMA
appraise modes be disabled.

This patch removes the compile time dependency and makes it a runtime
decision, based on the secure boot state of that platform.

Test results as follows:

-> x86-64 with secure boot enabled

[    0.015637] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix
[    0.015668] ima: Secure boot enabled: ignoring ima_appraise=fix boot parameter option

-> powerpc with secure boot disabled

[    0.000000] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix
[    0.000000] Secure boot mode disabled

-> Running the system without secure boot and with both options set:

CONFIG_IMA_APPRAISE_BOOTPARAM=y
CONFIG_IMA_ARCH_POLICY=y

Audit prompts "missing-hash" but still allow execution and, consequently,
filesystem labeling:

type=INTEGRITY_DATA msg=audit(07/09/2020 12:30:27.778:1691) : pid=4976
uid=root auid=root ses=2
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=appraise_data
cause=missing-hash comm=bash name=/usr/bin/evmctl dev="dm-0" ino=493150
res=no

Cc: stable@vger.kernel.org
Fixes: d958083a ("x86/ima: define arch_get_ima_policy() for x86")
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Cc: stable@vger.kernel.org # 5.0
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

parent 1768215a

security/integrity/ima/Kconfig

+1 −1

Original line number	Diff line number	Diff line
		@@ -232,7 +232,7 @@ config IMA_APPRAISE_REQUIRE_POLICY_SIGS

		config IMA_APPRAISE_BOOTPARAM
		bool "ima_appraise boot parameter"
		depends on IMA_APPRAISE && !IMA_ARCH_POLICY
		depends on IMA_APPRAISE
		default y
		help
		This option enables the different "ima_appraise=" modes

security/integrity/ima/ima_appraise.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,12 @@
		static int __init default_appraise_setup(char *str)
		{
		#ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
		if (arch_ima_get_secureboot()) {
		pr_info("Secure boot enabled: ignoring ima_appraise=%s boot parameter option",
		str);
		return 1;
		}

		if (strncmp(str, "off", 3) == 0)
		ima_appraise = 0;
		else if (strncmp(str, "log", 3) == 0)

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