Thanks to Miroslav, Petr and Marcos for the reviews!
V4: Use variable for /sys/kernel/debug. Be consistent with "" around variables. Fix path in commit message to /sys/kernel/debug/kprobes/enabled.
V3: Save and restore kprobe state also when test fails, by integrating it into setup_config() and cleanup(). Rename SYSFS variables in a more logical way. Sort test modules in alphabetical order. Rename module description.
V2: Save and restore kprobe state.
Michael Vetter (3): selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR selftests: livepatch: save and restore kprobe state selftests: livepatch: test livepatching a kprobed function
tools/testing/selftests/livepatch/Makefile | 3 +- .../testing/selftests/livepatch/functions.sh | 19 ++++-- .../selftests/livepatch/test-kprobe.sh | 62 +++++++++++++++++++ .../selftests/livepatch/test_modules/Makefile | 3 +- .../livepatch/test_modules/test_klp_kprobe.c | 38 ++++++++++++ 5 files changed, 117 insertions(+), 8 deletions(-) create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
This naming makes more sense according to the directory structure. Especially when we later add more paths.
Signed-off-by: Michael Vetter mvetter@suse.com --- tools/testing/selftests/livepatch/functions.sh | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index fc4c6a016d38..50361fceff06 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -6,7 +6,7 @@
MAX_RETRIES=600 RETRY_INTERVAL=".1" # seconds -KLP_SYSFS_DIR="/sys/kernel/livepatch" +SYSFS_KLP_DIR="/sys/kernel/livepatch"
# Kselftest framework requirement - SKIP code is 4 ksft_skip=4 @@ -322,7 +322,7 @@ function check_sysfs_rights() { local rel_path="$1"; shift local expected_rights="$1"; shift
- local path="$KLP_SYSFS_DIR/$mod/$rel_path" + local path="$SYSFS_KLP_DIR/$mod/$rel_path" local rights=$(/bin/stat --format '%A' "$path") if test "$rights" != "$expected_rights" ; then die "Unexpected access rights of $path: $expected_rights vs. $rights" @@ -338,7 +338,7 @@ function check_sysfs_value() { local rel_path="$1"; shift local expected_value="$1"; shift
- local path="$KLP_SYSFS_DIR/$mod/$rel_path" + local path="$SYSFS_KLP_DIR/$mod/$rel_path" local value=`cat $path` if test "$value" != "$expected_value" ; then die "Unexpected value in $path: $expected_value vs. $value"
Hi,
On Mon, 30 Sep 2024, Michael Vetter wrote:
This naming makes more sense according to the directory structure. Especially when we later add more paths.
Signed-off-by: Michael Vetter mvetter@suse.com
tools/testing/selftests/livepatch/functions.sh | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index fc4c6a016d38..50361fceff06 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -6,7 +6,7 @@ MAX_RETRIES=600 RETRY_INTERVAL=".1" # seconds -KLP_SYSFS_DIR="/sys/kernel/livepatch" +SYSFS_KLP_DIR="/sys/kernel/livepatch" # Kselftest framework requirement - SKIP code is 4 ksft_skip=4 @@ -322,7 +322,7 @@ function check_sysfs_rights() { local rel_path="$1"; shift local expected_rights="$1"; shift
- local path="$KLP_SYSFS_DIR/$mod/$rel_path"
- local path="$SYSFS_KLP_DIR/$mod/$rel_path" local rights=$(/bin/stat --format '%A' "$path") if test "$rights" != "$expected_rights" ; then die "Unexpected access rights of $path: $expected_rights vs. $rights"
@@ -338,7 +338,7 @@ function check_sysfs_value() { local rel_path="$1"; shift local expected_value="$1"; shift
- local path="$KLP_SYSFS_DIR/$mod/$rel_path"
- local path="$SYSFS_KLP_DIR/$mod/$rel_path" local value=`cat $path` if test "$value" != "$expected_value" ; then die "Unexpected value in $path: $expected_value vs. $value"
I am sorry I was not explicit enough previously. There are still /sys/kernel/livepatch occurrences in tools/testing/selftest/livepatch/ which can be replaced with this new variable. They are there for quite some time but it would be really nice if you could replace them all to make it consistent since you are touching it.
Thank you, Miroslav
Save the state of /sys/kernel/debug/kprobes/enabled during setup_config() and restore it during cleanup().
This is in preparation for a future commit that will add a test that should confirm that we cannot livepatch a kprobed function if that kprobe has a post handler.
Signed-off-by: Michael Vetter mvetter@suse.com --- tools/testing/selftests/livepatch/functions.sh | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index 50361fceff06..91102562db58 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -6,7 +6,10 @@
MAX_RETRIES=600 RETRY_INTERVAL=".1" # seconds -SYSFS_KLP_DIR="/sys/kernel/livepatch" +SYSFS_KERNEL_DIR="/sys/kernel" +SYSFS_KLP_DIR="$SYSFS_KERNEL_DIR/livepatch" +SYSFS_DEBUG_DIR="$SYSFS_KERNEL_DIR/debug" +SYSFS_KPROBES_DIR="$SYSFS_DEBUG_DIR/kprobes"
# Kselftest framework requirement - SKIP code is 4 ksft_skip=4 @@ -55,22 +58,26 @@ function die() { }
function push_config() { - DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \ + DYNAMIC_DEBUG=$(grep '^kernel/livepatch' "$SYSFS_DEBUG_DIR/dynamic_debug/control" | \ awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}') FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled) + KPROBE_ENABLED=$(cat "$SYSFS_KPROBES_DIR/enabled") }
function pop_config() { if [[ -n "$DYNAMIC_DEBUG" ]]; then - echo -n "$DYNAMIC_DEBUG" > /sys/kernel/debug/dynamic_debug/control + echo -n "$DYNAMIC_DEBUG" > "$SYSFS_DEBUG_DIR/dynamic_debug/control" fi if [[ -n "$FTRACE_ENABLED" ]]; then sysctl kernel.ftrace_enabled="$FTRACE_ENABLED" &> /dev/null fi + if [[ -n "$KPROBE_ENABLED" ]]; then + echo "$KPROBE_ENABLED" > "$SYSFS_KPROBES_DIR/enabled" + fi }
function set_dynamic_debug() { - cat <<-EOF > /sys/kernel/debug/dynamic_debug/control + cat <<-EOF > "$SYSFS_DEBUG_DIR/dynamic_debug/control" file kernel/livepatch/* +p func klp_try_switch_task -p EOF
The test proves that a function that is being kprobed and uses a post_handler cannot be livepatched.
Only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be registered to any given function at a time.
Signed-off-by: Michael Vetter mvetter@suse.com --- tools/testing/selftests/livepatch/Makefile | 3 +- .../selftests/livepatch/test-kprobe.sh | 62 +++++++++++++++++++ .../selftests/livepatch/test_modules/Makefile | 3 +- .../livepatch/test_modules/test_klp_kprobe.c | 38 ++++++++++++ 4 files changed, 104 insertions(+), 2 deletions(-) create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile index 35418a4790be..a080eb54a215 100644 --- a/tools/testing/selftests/livepatch/Makefile +++ b/tools/testing/selftests/livepatch/Makefile @@ -10,7 +10,8 @@ TEST_PROGS := \ test-state.sh \ test-ftrace.sh \ test-sysfs.sh \ - test-syscall.sh + test-syscall.sh \ + test-kprobe.sh
TEST_FILES := settings
diff --git a/tools/testing/selftests/livepatch/test-kprobe.sh b/tools/testing/selftests/livepatch/test-kprobe.sh new file mode 100755 index 000000000000..115065156016 --- /dev/null +++ b/tools/testing/selftests/livepatch/test-kprobe.sh @@ -0,0 +1,62 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2024 SUSE +# Author: Michael Vetter mvetter@suse.com + +. $(dirname $0)/functions.sh + +MOD_LIVEPATCH=test_klp_livepatch +MOD_KPROBE=test_klp_kprobe + +setup_config + +# Kprobe a function and verify that we can't livepatch that same function +# when it uses a post_handler since only one IPMODIFY maybe be registered +# to any given function at a time. + +start_test "livepatch interaction with kprobed function with post_handler" + +echo 1 > "$SYSFS_KPROBES_DIR/enabled" + +load_mod $MOD_KPROBE has_post_handler=true +load_failing_mod $MOD_LIVEPATCH +unload_mod $MOD_KPROBE + +check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=true +% insmod test_modules/$MOD_LIVEPATCH.ko +livepatch: enabling patch '$MOD_LIVEPATCH' +livepatch: '$MOD_LIVEPATCH': initializing patching transition +livepatch: failed to register ftrace handler for function 'cmdline_proc_show' (-16) +livepatch: failed to patch object 'vmlinux' +livepatch: failed to enable patch '$MOD_LIVEPATCH' +livepatch: '$MOD_LIVEPATCH': canceling patching transition, going to unpatch +livepatch: '$MOD_LIVEPATCH': completing unpatching transition +livepatch: '$MOD_LIVEPATCH': unpatching complete +insmod: ERROR: could not insert module test_modules/$MOD_LIVEPATCH.ko: Device or resource busy +% rmmod test_klp_kprobe" + +start_test "livepatch interaction with kprobed function without post_handler" + +load_mod $MOD_KPROBE has_post_handler=false +load_lp $MOD_LIVEPATCH + +unload_mod $MOD_KPROBE +disable_lp $MOD_LIVEPATCH +unload_lp $MOD_LIVEPATCH + +check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=false +% insmod test_modules/$MOD_LIVEPATCH.ko +livepatch: enabling patch '$MOD_LIVEPATCH' +livepatch: '$MOD_LIVEPATCH': initializing patching transition +livepatch: '$MOD_LIVEPATCH': starting patching transition +livepatch: '$MOD_LIVEPATCH': completing patching transition +livepatch: '$MOD_LIVEPATCH': patching complete +% rmmod test_klp_kprobe +% echo 0 > /sys/kernel/livepatch/$MOD_LIVEPATCH/enabled +livepatch: '$MOD_LIVEPATCH': initializing unpatching transition +livepatch: '$MOD_LIVEPATCH': starting unpatching transition +livepatch: '$MOD_LIVEPATCH': completing unpatching transition +livepatch: '$MOD_LIVEPATCH': unpatching complete +% rmmod $MOD_LIVEPATCH" + +exit 0 diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile index e6e638c4bcba..939230e571f5 100644 --- a/tools/testing/selftests/livepatch/test_modules/Makefile +++ b/tools/testing/selftests/livepatch/test_modules/Makefile @@ -6,11 +6,12 @@ obj-m += test_klp_atomic_replace.o \ test_klp_callbacks_demo.o \ test_klp_callbacks_demo2.o \ test_klp_callbacks_mod.o \ + test_klp_kprobe.o \ test_klp_livepatch.o \ + test_klp_shadow_vars.o \ test_klp_state.o \ test_klp_state2.o \ test_klp_state3.o \ - test_klp_shadow_vars.o \ test_klp_syscall.o
# Ensure that KDIR exists, otherwise skip the compilation diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c b/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c new file mode 100644 index 000000000000..67a8d29012f6 --- /dev/null +++ b/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2024 Marcos Paulo de Souza mpdesouza@suse.com +// Copyright (C) 2024 Michael Vetter mvetter@suse.com + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/kprobes.h> + +static bool has_post_handler = true; +module_param(has_post_handler, bool, 0444); + +static void __kprobes post_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ +} + +static struct kprobe kp = { + .symbol_name = "cmdline_proc_show", +}; + +static int __init kprobe_init(void) +{ + if (has_post_handler) + kp.post_handler = post_handler; + + return register_kprobe(&kp); +} + +static void __exit kprobe_exit(void) +{ + unregister_kprobe(&kp); +} + +module_init(kprobe_init) +module_exit(kprobe_exit) +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Michael Vetter mvetter@suse.com"); +MODULE_DESCRIPTION("Livepatch test: kprobe function");
Hi,
On Mon, 30 Sep 2024, Michael Vetter wrote:
The test proves that a function that is being kprobed and uses a post_handler cannot be livepatched.
Only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be registered to any given function at a time.
Signed-off-by: Michael Vetter mvetter@suse.com
since my memory is short, I wondered why you need a separate module to register a kprobe for cmdline_proc_show() in vmlinux and why it cannot be achieved through tracefs. So... the test ensures that FTRACE_OPS_FL_IPMODIFY is exclusive. A kprobe sets FTRACE_OPS_FL_IPMODIFY flag if and only if post_handler is not NULL which also indicates a situation when regs->ip may be changed in that kprobe. This is something which cannot be done in tracefs and hence the module.
It was not clear to me from the changelog.
Miroslav
On Mon, 2024-09-30 at 11:33 +0200, Michael Vetter wrote:
Thanks to Miroslav, Petr and Marcos for the reviews!
As the only changes were regarding bash nitpicks I keep my review from earlier patchset, so:
Reviewed-by: Marcos Paulo de Souza mpdesouza@suse.com
V4: Use variable for /sys/kernel/debug. Be consistent with "" around variables. Fix path in commit message to /sys/kernel/debug/kprobes/enabled.
V3: Save and restore kprobe state also when test fails, by integrating it into setup_config() and cleanup(). Rename SYSFS variables in a more logical way. Sort test modules in alphabetical order. Rename module description.
V2: Save and restore kprobe state.
Michael Vetter (3): selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR selftests: livepatch: save and restore kprobe state selftests: livepatch: test livepatching a kprobed function
tools/testing/selftests/livepatch/Makefile | 3 +- .../testing/selftests/livepatch/functions.sh | 19 ++++-- .../selftests/livepatch/test-kprobe.sh | 62 +++++++++++++++++++ .../selftests/livepatch/test_modules/Makefile | 3 +- .../livepatch/test_modules/test_klp_kprobe.c | 38 ++++++++++++ 5 files changed, 117 insertions(+), 8 deletions(-) create mode 100755 tools/testing/selftests/livepatch/test-kprobe.sh create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c
linux-kselftest-mirror@lists.linaro.org
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Marcos Paulo de Souza -
Michael Vetter -
Miroslav Benes