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>

MAINTAINERS

@@ -9581,6 +9581,7 @@ LINUX KERNEL DUMP TEST MODULE (LKDTM)
 M:	Kees Cook <keescook@chromium.org>
 S:	Maintained
 F:	drivers/misc/lkdtm/*
+F:	tools/testing/selftests/lkdtm/*
 
 LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
 M:	Alan Stern <stern@rowland.harvard.edu>

tools/testing/selftests/Makefile

@@ -26,6 +26,7 @@ TARGETS += kexec
 TARGETS += kvm
 TARGETS += lib
 TARGETS += livepatch
+TARGETS += lkdtm
 TARGETS += membarrier
 TARGETS += memfd
 TARGETS += memory-hotplug

tools/testing/selftests/lkdtm/Makefile

+# SPDX-License-Identifier: GPL-2.0
+# Makefile for LKDTM regression tests
+
+include ../lib.mk
+
+# NOTE: $(OUTPUT) won't get default value if used before lib.mk
+TEST_FILES := tests.txt
+TEST_GEN_PROGS = $(patsubst %,$(OUTPUT)/%.sh,$(shell awk '{print $$1}' tests.txt | sed -e 's/\#//'))
+all: $(TEST_GEN_PROGS)
+
+$(OUTPUT)/%: run.sh tests.txt
+	install -m 0744 run.sh $@

tools/testing/selftests/lkdtm/config

+CONFIG_LKDTM=y

tools/testing/selftests/lkdtm/run.sh

+#!/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

tools/testing/selftests/lkdtm/tests.txt

+#PANIC
+BUG kernel BUG at
+WARNING WARNING:
+WARNING_MESSAGE message trigger
+EXCEPTION
+#LOOP Hangs the system
+#EXHAUST_STACK Corrupts memory on failure
+#CORRUPT_STACK Crashes entire system on success
+#CORRUPT_STACK_STRONG Crashes entire system on success
+CORRUPT_LIST_ADD list_add corruption
+CORRUPT_LIST_DEL list_del corruption
+CORRUPT_USER_DS Invalid address limit on user-mode return
+STACK_GUARD_PAGE_LEADING
+STACK_GUARD_PAGE_TRAILING
+UNSET_SMEP CR4 bits went missing
+DOUBLE_FAULT
+UNALIGNED_LOAD_STORE_WRITE
+#OVERWRITE_ALLOCATION Corrupts memory on failure
+#WRITE_AFTER_FREE Corrupts memory on failure
+READ_AFTER_FREE
+#WRITE_BUDDY_AFTER_FREE Corrupts memory on failure
+READ_BUDDY_AFTER_FREE
+SLAB_FREE_DOUBLE
+SLAB_FREE_CROSS
+SLAB_FREE_PAGE
+#SOFTLOCKUP Hangs the system
+#HARDLOCKUP Hangs the system
+#SPINLOCKUP Hangs the system
+#HUNG_TASK Hangs the system
+EXEC_DATA
+EXEC_STACK
+EXEC_KMALLOC
+EXEC_VMALLOC
+EXEC_RODATA
+EXEC_USERSPACE
+EXEC_NULL
+ACCESS_USERSPACE
+ACCESS_NULL
+WRITE_RO
+WRITE_RO_AFTER_INIT
+WRITE_KERN
+REFCOUNT_INC_OVERFLOW
+REFCOUNT_ADD_OVERFLOW
+REFCOUNT_INC_NOT_ZERO_OVERFLOW
+REFCOUNT_ADD_NOT_ZERO_OVERFLOW
+REFCOUNT_DEC_ZERO
+REFCOUNT_DEC_NEGATIVE Negative detected: saturated
+REFCOUNT_DEC_AND_TEST_NEGATIVE Negative detected: saturated
+REFCOUNT_SUB_AND_TEST_NEGATIVE Negative detected: saturated
+REFCOUNT_INC_ZERO
+REFCOUNT_ADD_ZERO
+REFCOUNT_INC_SATURATED Saturation detected: still saturated
+REFCOUNT_DEC_SATURATED Saturation detected: still saturated
+REFCOUNT_ADD_SATURATED Saturation detected: still saturated
+REFCOUNT_INC_NOT_ZERO_SATURATED
+REFCOUNT_ADD_NOT_ZERO_SATURATED
+REFCOUNT_DEC_AND_TEST_SATURATED Saturation detected: still saturated
+REFCOUNT_SUB_AND_TEST_SATURATED Saturation detected: still saturated
+#REFCOUNT_TIMING timing only
+#ATOMIC_TIMING timing only
+USERCOPY_HEAP_SIZE_TO
+USERCOPY_HEAP_SIZE_FROM
+USERCOPY_HEAP_WHITELIST_TO
+USERCOPY_HEAP_WHITELIST_FROM
+USERCOPY_STACK_FRAME_TO
+USERCOPY_STACK_FRAME_FROM
+USERCOPY_STACK_BEYOND
+USERCOPY_KERNEL
+USERCOPY_KERNEL_DS
+STACKLEAK_ERASING OK: the rest of the thread stack is properly erased
+CFI_FORWARD_PROTO