From 62597edf6340191511bdf9a7f64fa315ddc58805 Mon Sep 17 00:00:00 2001 From: Michael Vetter Date: Thu, 17 Oct 2024 22:01:32 +0200 Subject: [PATCH] selftests: livepatch: test livepatching a kprobed function 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. Note that the conflicting kprobe could not be created using the tracefs interface, see Documentation/trace/kprobetrace.rst. This interface uses only the pre_handler(), see alloc_trace_kprobe(). But FTRACE_OPS_FL_IPMODIFY is used only when the kprobe is using a post_handler, see arm_kprobe_ftrace(). Signed-off-by: Michael Vetter Reviewed-by: Miroslav Benes Reviewed-by: Joe Lawrence Tested-by: Marcos Paulo de Souza Reviewed-by: Marcos Paulo de Souza Reviewed-by: Petr Mladek Tested-by: Petr Mladek Link: https://lore.kernel.org/r/20241017200132.21946-4-mvetter@suse.com Signed-off-by: Petr Mladek --- 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 + +. $(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 +// Copyright (C) 2024 Michael Vetter + +#include +#include +#include + +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 "); +MODULE_DESCRIPTION("Livepatch test: kprobe function");