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| author |   Kees Cook <keescook@chromium.org> | 2021-04-01 16:23:47 -0700 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2021-04-08 14:05:20 +0200 |
| commit | 68ef8735d253f3d840082b78f996bf2d89ee6e5f (patch) | |
| tree | 56d0efc5657399b907ca874ddea2a8140c3976e9 /tools/testing/selftests | |
| parent | x86/entry: Enable random_kstack_offset support (diff) | |
| download | wireguard-linux-68ef8735d253f3d840082b78f996bf2d89ee6e5f.tar.xz wireguard-linux-68ef8735d253f3d840082b78f996bf2d89ee6e5f.zip | |
lkdtm: Add REPORT_STACK for checking stack offsets
For validating the stack offset behavior, report the offset from a given
process's first seen stack address. Add s script to calculate the results
to the LKDTM kselftests.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210401232347.2791257-7-keescook@chromium.org
Diffstat (limited to 'tools/testing/selftests')
| -rw-r--r-- | tools/testing/selftests/lkdtm/.gitignore | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/lkdtm/Makefile | 1 | ||||
| -rwxr-xr-x | tools/testing/selftests/lkdtm/stack-entropy.sh | 36 |
3 files changed, 38 insertions, 0 deletions
diff --git a/tools/testing/selftests/lkdtm/.gitignore b/tools/testing/selftests/lkdtm/.gitignore index f26212605b6b..d4b0be857deb 100644 --- a/tools/testing/selftests/lkdtm/.gitignore +++ b/tools/testing/selftests/lkdtm/.gitignore @@ -1,2 +1,3 @@ *.sh !run.sh +!stack-entropy.sh diff --git a/tools/testing/selftests/lkdtm/Makefile b/tools/testing/selftests/lkdtm/Makefile index 1bcc9ee990eb..c71109ceeb2d 100644 --- a/tools/testing/selftests/lkdtm/Makefile +++ b/tools/testing/selftests/lkdtm/Makefile @@ -5,6 +5,7 @@ include ../lib.mk # NOTE: $(OUTPUT) won't get default value if used before lib.mk TEST_FILES := tests.txt +TEST_PROGS := stack-entropy.sh TEST_GEN_PROGS = $(patsubst %,$(OUTPUT)/%.sh,$(shell awk '{print $$1}' tests.txt | sed -e 's/\#//')) all: $(TEST_GEN_PROGS) diff --git a/tools/testing/selftests/lkdtm/stack-entropy.sh b/tools/testing/selftests/lkdtm/stack-entropy.sh new file mode 100755 index 000000000000..b1b8a5097cbb --- /dev/null +++ b/tools/testing/selftests/lkdtm/stack-entropy.sh @@ -0,0 +1,36 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# +# Measure kernel stack entropy by sampling via LKDTM's REPORT_STACK test. +set -e +samples="${1:-1000}" + +# Capture dmesg continuously since it may fill up depending on sample size. +log=$(mktemp -t stack-entropy-XXXXXX) +dmesg --follow >"$log" & pid=$! +report=-1 +for i in $(seq 1 $samples); do + echo "REPORT_STACK" >/sys/kernel/debug/provoke-crash/DIRECT + if [ -t 1 ]; then + percent=$(( 100 * $i / $samples )) + if [ "$percent" -ne "$report" ]; then + /bin/echo -en "$percent%\r" + report="$percent" + fi + fi +done +kill "$pid" + +# Count unique offsets since last run. +seen=$(tac "$log" | grep -m1 -B"$samples"0 'Starting stack offset' | \ + grep 'Stack offset' | awk '{print $NF}' | sort | uniq -c | wc -l) +bits=$(echo "obase=2; $seen" | bc | wc -L) +echo "Bits of stack entropy: $bits" +rm -f "$log" + +# We would expect any functional stack randomization to be at least 5 bits. +if [ "$bits" -lt 5 ]; then + exit 1 +else + exit 0 +fi |