Message-ID: <8591d8b8-969a-bd6a-8ef5-3fd908ac16c7@kernel.org>
Date:   Thu, 9 Jan 2020 16:19:07 -0700
From:   shuah <shuah@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        Alexander Popov <alex.popov@...ux.com>,
        linux-kselftest@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        shuah <shuah@...nel.org>
Subject: Re: [PATCH v2] selftests/lkdtm: Add tests for LKDTM targets

On 12/30/19 3:57 PM, Kees Cook wrote:
> 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@...omium.org>
> ---
> v2: refreshed for v5.5, added new tests since v1
> v1: https://lore.kernel.org/lkml/201905091013.E228F0F0BE@keescook/
> ---
>   MAINTAINERS                             |  1 +
>   tools/testing/selftests/Makefile        |  1 +
>   tools/testing/selftests/lkdtm/Makefile  | 12 ++++
>   tools/testing/selftests/lkdtm/config    |  1 +
>   tools/testing/selftests/lkdtm/run.sh    | 91 +++++++++++++++++++++++++
>   tools/testing/selftests/lkdtm/tests.txt | 70 +++++++++++++++++++
>   6 files changed, 176 insertions(+)
>   create mode 100644 tools/testing/selftests/lkdtm/Makefile
>   create mode 100644 tools/testing/selftests/lkdtm/config
>   create mode 100755 tools/testing/selftests/lkdtm/run.sh
>   create mode 100644 tools/testing/selftests/lkdtm/tests.txt
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cc0a4a8ae06a..eacc00c6cfd5 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9578,6 +9578,7 @@ LINUX KERNEL DUMP TEST MODULE (LKDTM)
>   M:	Kees Cook <keescook@...omium.org>
>   S:	Maintained
>   F:	drivers/misc/lkdtm/*
> +F:	tools/testing/selftests/lkdtm/*
>   
>   LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
>   M:	Alan Stern <stern@...land.harvard.edu>
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index b001c602414b..f0b02a12ba39 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/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
> diff --git a/tools/testing/selftests/lkdtm/Makefile b/tools/testing/selftests/lkdtm/Makefile
> new file mode 100644
> index 000000000000..1bcc9ee990eb
> --- /dev/null
> +++ b/tools/testing/selftests/lkdtm/Makefile
> @@ -0,0 +1,12 @@
> +# 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 $@
> diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config
> new file mode 100644
> index 000000000000..d874990e442b
> --- /dev/null
> +++ b/tools/testing/selftests/lkdtm/config
> @@ -0,0 +1 @@
> +CONFIG_LKDTM=y
> diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh
> new file mode 100755
> index 000000000000..793ee0d5d5a3
> --- /dev/null
> +++ b/tools/testing/selftests/lkdtm/run.sh
> @@ -0,0 +1,91 @@
> +#!/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
> +
> +# 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 4

Please add a define for this to indicate that this the kselftest
skip code.

> +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 '$test' in tests.txt"
> +	exit 4
> +fi
> +# Check that the test is known to LKDTM.
> +if ! egrep -q '^'"$test"'$' "$TRIGGER" ; then
> +	echo "Skipped: test '$test' missing in $TRIGGER!"
> +	exit 4
> +fi

Same here

> +
> +# 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 4

Same here

> +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 4
> +	else
> +		echo "$test: missing '$expect': [FAIL]"
> +		exit 1
> +	fi
> +fi
> diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt
> new file mode 100644
> index 000000000000..fc55f8ef8bee
> --- /dev/null
> +++ b/tools/testing/selftests/lkdtm/tests.txt
> @@ -0,0 +1,70 @@
> +#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
> +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
> 

Rest looks good. I can pull the v3 for 5.6-rc1

thanks,
-- Shuah

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