selftests/lkdtm: Add tests for LKDTM targets

This adds a basic framework for running all the "safe" LKDTM tests. This
will allow easy introspection into any selftest logs to examine the
results of most LKDTM tests.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 92 insertions, 0 deletions

diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh
new file mode 100755
index 000000000000..dadf819148a4
--- /dev/null
+++ b/tools/testing/selftests/lkdtm/run.sh
@@ -0,0 +1,92 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# This reads tests.txt for the list of LKDTM tests to invoke. Any marked
+# with a leading "#" are skipped. The rest of the line after the
+# test name is either the text to look for in dmesg for a "success",
+# or the rationale for why a test is marked to be skipped.
+#
+set -e
+TRIGGER=/sys/kernel/debug/provoke-crash/DIRECT
+KSELFTEST_SKIP_TEST=4
+
+# Verify we have LKDTM available in the kernel.
+if [ ! -r $TRIGGER ] ; then
+	/sbin/modprobe -q lkdtm || true
+	if [ ! -r $TRIGGER ] ; then
+		echo "Cannot find $TRIGGER (missing CONFIG_LKDTM?)"
+	else
+		echo "Cannot write $TRIGGER (need to run as root?)"
+	fi
+	# Skip this test
+	exit $KSELFTEST_SKIP_TEST
+fi
+
+# Figure out which test to run from our script name.
+test=$(basename $0 .sh)
+# Look up details about the test from master list of LKDTM tests.
+line=$(egrep '^#?'"$test"'\b' tests.txt)
+if [ -z "$line" ]; then
+	echo "Skipped: missing test '$test' in tests.txt"
+	exit $KSELFTEST_SKIP_TEST
+fi
+# Check that the test is known to LKDTM.
+if ! egrep -q '^'"$test"'$' "$TRIGGER" ; then
+	echo "Skipped: test '$test' missing in $TRIGGER!"
+	exit $KSELFTEST_SKIP_TEST
+fi
+
+# Extract notes/expected output from test list.
+test=$(echo "$line" | cut -d" " -f1)
+if echo "$line" | grep -q ' ' ; then
+	expect=$(echo "$line" | cut -d" " -f2-)
+else
+	expect=""
+fi
+
+# If the test is commented out, report a skip
+if echo "$test" | grep -q '^#' ; then
+	test=$(echo "$test" | cut -c2-)
+	if [ -z "$expect" ]; then
+		expect="crashes entire system"
+	fi
+	echo "Skipping $test: $expect"
+	exit $KSELFTEST_SKIP_TEST
+fi
+
+# If no expected output given, assume an Oops with back trace is success.
+if [ -z "$expect" ]; then
+	expect="call trace:"
+fi
+
+# Clear out dmesg for output reporting
+dmesg -c >/dev/null
+
+# Prepare log for report checking
+LOG=$(mktemp --tmpdir -t lkdtm-XXXXXX)
+cleanup() {
+	rm -f "$LOG"
+}
+trap cleanup EXIT
+
+# Most shells yell about signals and we're expecting the "cat" process
+# to usually be killed by the kernel. So we have to run it in a sub-shell
+# and silence errors.
+($SHELL -c 'cat <(echo '"$test"') >'"$TRIGGER" 2>/dev/null) || true
+
+# Record and dump the results
+dmesg -c >"$LOG"
+cat "$LOG"
+# Check for expected output
+if egrep -qi "$expect" "$LOG" ; then
+	echo "$test: saw '$expect': ok"
+	exit 0
+else
+	if egrep -qi XFAIL: "$LOG" ; then
+		echo "$test: saw 'XFAIL': [SKIP]"
+		exit $KSELFTEST_SKIP_TEST
+	else
+		echo "$test: missing '$expect': [FAIL]"
+		exit 1
+	fi
+fi