[PATCH v6 4/4] IMA: Add test for kexec cmdline measurement

* [PATCH v6 4/4] IMA: Add test for kexec cmdline measurement
@ 2020-07-28  0:13 Petr Vorel
  2020-07-28  1:06 ` Lachlan Sneff
  2020-07-30 19:58 ` Mimi Zohar
  0 siblings, 2 replies; 4+ messages in thread
From: Petr Vorel @ 2020-07-28  0:13 UTC (permalink / raw)
  To: ltp
  Cc: Lachlan Sneff, Lakshmi Ramasubramanian, Mimi Zohar, balajib,
	linux-integrity, Petr Vorel, Mimi Zohar

From: Lachlan Sneff <t-josne@linux.microsoft.com>

IMA policy can be set to measure the command line passed in the kexec
system call. Add a testcase that verifies that the IMA subsystem
correctly measure the cmdline specified during a kexec.

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Lachlan Sneff <t-josne@linux.microsoft.com>
[ pvorel: improved setup, various LTP API cleanup ]
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
Changes v5->v6:
* move --reuse-cmdline from setup to kexec_test()

Sorry for the noise.

Kind regards,
Petr

 runtest/ima                                   |   1 +
 .../kernel/security/integrity/ima/README.md   |   8 ++
 .../integrity/ima/datafiles/kexec.policy      |   1 +
 .../security/integrity/ima/tests/ima_kexec.sh | 120 ++++++++++++++++++
 4 files changed, 130 insertions(+)
 create mode 100644 testcases/kernel/security/integrity/ima/datafiles/kexec.policy
 create mode 100755 testcases/kernel/security/integrity/ima/tests/ima_kexec.sh

diff --git a/runtest/ima b/runtest/ima
index 309d47420..5f4b4a7a1 100644
--- a/runtest/ima
+++ b/runtest/ima
@@ -4,4 +4,5 @@ ima_policy ima_policy.sh
 ima_tpm ima_tpm.sh
 ima_violations ima_violations.sh
 ima_keys ima_keys.sh
+ima_kexec ima_kexec.sh
 evm_overlay evm_overlay.sh
diff --git a/testcases/kernel/security/integrity/ima/README.md b/testcases/kernel/security/integrity/ima/README.md
index 732cd912f..d4644ba39 100644
--- a/testcases/kernel/security/integrity/ima/README.md
+++ b/testcases/kernel/security/integrity/ima/README.md
@@ -36,6 +36,14 @@ CONFIG_SYSTEM_TRUSTED_KEYS="/etc/keys/ima-local-ca.pem"
 
 Test also requires loaded policy with `func=KEY_CHECK`, see example in `keycheck.policy`.
 
+### IMA kexec test
+
+`ima_kexec.sh` requires loaded policy which contains `measure func=KEXEC_CMDLINE`,
+see example in `kexec.policy`.
+
+The test attempts to kexec the existing running kernel image.
+To kexec a different kernel image export `IMA_KEXEC_IMAGE=<pathname>`.
+
 ## EVM tests
 
 `evm_overlay.sh` requires a builtin IMA appraise tcb policy (e.g. `ima_policy=appraise_tcb`
diff --git a/testcases/kernel/security/integrity/ima/datafiles/kexec.policy b/testcases/kernel/security/integrity/ima/datafiles/kexec.policy
new file mode 100644
index 000000000..58d66369e
--- /dev/null
+++ b/testcases/kernel/security/integrity/ima/datafiles/kexec.policy
@@ -0,0 +1 @@
+measure func=KEXEC_CMDLINE
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_kexec.sh b/testcases/kernel/security/integrity/ima/tests/ima_kexec.sh
new file mode 100755
index 000000000..30bbd066e
--- /dev/null
+++ b/testcases/kernel/security/integrity/ima/tests/ima_kexec.sh
@@ -0,0 +1,120 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2020 Microsoft Corporation
+# Copyright (c) 2020 Petr Vorel <pvorel@suse.cz>
+# Author: Lachlan Sneff <t-josne@linux.microsoft.com>
+#
+# Verify that kexec cmdline is measured correctly.
+# Test attempts to kexec the existing running kernel image.
+# To kexec a different kernel image export IMA_KEXEC_IMAGE=<pathname>.
+
+TST_NEEDS_CMDS="grep kexec sed"
+TST_CNT=3
+TST_NEEDS_DEVICE=1
+TST_SETUP="setup"
+
+. ima_setup.sh
+
+IMA_KEXEC_IMAGE="${IMA_KEXEC_IMAGE:-/boot/vmlinuz-$(uname -r)}"
+REQUIRED_POLICY='^measure.*func=KEXEC_CMDLINE'
+
+measure()
+{
+	local cmdline="$1"
+	local algorithm digest expected_digest found
+
+	printf "$cmdline" > file1
+	grep "kexec-cmdline" $ASCII_MEASUREMENTS > file2
+
+	while read found
+	do
+		algorithm=$(echo "$found" | cut -d' ' -f4 | cut -d':' -f1)
+		digest=$(echo "$found" | cut -d' ' -f4 | cut -d':' -f2)
+
+		expected_digest=$(compute_digest $algorithm file1)
+
+		if [ "$digest" = "$expected_digest" ]; then
+			return 0
+		fi
+	done < file2
+
+	return 1
+}
+
+setup()
+{
+	tst_res TINFO "using kernel $IMA_KEXEC_IMAGE"
+
+	if [ ! -f "$IMA_KEXEC_IMAGE" ]; then
+		tst_brk TCONF "kernel image not found, specify path in \$IMA_KEXEC_IMAGE"
+	fi
+
+	if check_policy_readable; then
+		require_ima_policy_content "$REQUIRED_POLICY"
+		policy_readable=1
+	fi
+}
+
+kexec_failure_hint()
+{
+	local sb_enabled
+
+	if tst_cmd_available bootctl; then
+		if bootctl status 2>/dev/null | grep -qi 'Secure Boot: enabled'; then
+			sb_enabled=1
+		fi
+	elif tst_cmd_available dmesg; then
+		if dmesg | grep -qi 'Secure boot enabled'; then
+			sb_enabled=1
+		fi
+	fi
+	if [ "$sb_enabled" ]; then
+		tst_res TWARN "secure boot is enabled, kernel image may not be signed"
+	fi
+
+	if check_ima_policy_content '^appraise.*func=KEXEC_KERNEL_CHECK'; then
+		tst_res TWARN "'func=KEXEC_KERNEL_CHECK' appraise policy loaded, kernel image may not be signed"
+	fi
+}
+
+kexec_test()
+{
+	local param="$1"
+	local cmdline="$2"
+	local res=TFAIL
+	local kexec_cmd
+
+	kexec_cmd="$param=$cmdline"
+	if [ "$param" = '--reuse-cmdline' ]; then
+		cmdline="$(sed 's/BOOT_IMAGE=[^ ]* //' /proc/cmdline)"
+		kexec_cmd="$param"
+	fi
+
+	kexec_cmd="kexec -s -l $IMA_KEXEC_IMAGE $kexec_cmd"
+	tst_res TINFO "testing $kexec_cmd"
+	if ! $kexec_cmd 2>err; then
+		kexec_failure_hint
+		tst_brk TBROK "kexec failed: $(cat err)"
+	fi
+
+	ROD kexec -su
+	if ! measure "$cmdline"; then
+		if [ "$policy_readable" != 1 ]; then
+			tst_res TWARN "policy not readable, it might not contain required policy '$REQUIRED_POLICY'"
+			res=TBROK
+		fi
+		tst_brk $res "unable to find a correct measurement"
+	fi
+	tst_res TPASS "kexec cmdline was measured correctly"
+}
+
+test()
+{
+	case $1 in
+	1) kexec_test '--reuse-cmdline';;
+	2) kexec_test '--append' 'foo';;
+	3) kexec_test '--command-line' 'bar';;
+	esac
+}
+
+tst_run
-- 
2.27.0


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