| Message ID | 20240917135059.73346-1-mvetter@suse.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] selftests: livepatch: test livepatching a kprobed function | expand |
On Tue 2024-09-17 15:50:53, 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. > > --- /dev/null > +++ b/tools/testing/selftests/livepatch/test-kprobe.sh > @@ -0,0 +1,65 @@ > +#!/bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (C) 2024 SUSE > +# Author: Michael Vetter <mvetter@suse.com> > + > +. $(dirname $0)/functions.sh > + > +MOD_LIVEPATCH=test_klp_livepatch > +MOD_KPROBE=test_klp_kprobe > + > +setup_config > + > +# Kprobe a function and verify that we can't livepatch that same function > +# when it uses a post_handler since only one IPMODIFY maybe be registered > +# to any given function at a time. > + > +start_test "livepatch interaction with kprobed function with post_handler" > + > +STATE=$(cat /sys/kernel/debug/kprobes/enabled) > +echo 1 > /sys/kernel/debug/kprobes/enabled > + > +load_mod $MOD_KPROBE has_post_handler=true > +load_failing_mod $MOD_LIVEPATCH > +unload_mod $MOD_KPROBE [...] > +echo $STATE > /sys/kernel/debug/kprobes/enabled The original state won't get restored when the test fails. A better solution would be to integrate this into setup_config() and cleanup() in /tools/testing/selftests/livepatch/functions.sh Also it would be great to avoid hard-coding /sys/kernel/debug. See KLP_SYSFS_DIR="/sys/kernel/livepatch" in /tools/testing/selftests/livepatch/functions.sh I would replace it with: KERNEL_SYSFS_DIR="/sys/kernel" KLP_SYSFS_DIR="$KERNEL_SYSFS_DIR/livepatch" DEBUG_SYSFS_DIR="$KERNEL_SYSFS_DIR/debug" KPROBES_SYSFS_DIR="$DEBUG_SYSFS_DIR/kprobes" It would actually look better with switched ordering: 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" But this would require renaming KLP_SYSFS_DIR everywhere in a separate (prerequisite) patch. It would be nice but I do not want to force you to do it ;-) > --- a/tools/testing/selftests/livepatch/test_modules/Makefile > +++ b/tools/testing/selftests/livepatch/test_modules/Makefile > @@ -11,7 +11,8 @@ obj-m += test_klp_atomic_replace.o \ > test_klp_state2.o \ > test_klp_state3.o \ > test_klp_shadow_vars.o \ > - test_klp_syscall.o > + test_klp_syscall.o \ > + test_klp_kprobe.o Nit: Please, put it in alphabetical order. It is not a big deal. The ordering helps searching. The list already is almost sorted. And the patch needs to be updated anyway. > # Ensure that KDIR exists, otherwise skip the compilation > modules: > 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..49b579ea1054 > --- /dev/null > +++ b/tools/testing/selftests/livepatch/test_modules/test_klp_kprobe.c > @@ -0,0 +1,38 @@ [...] > +module_init(kprobe_init) > +module_exit(kprobe_exit) > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Michael Vetter <mvetter@suse.com>"); > +MODULE_DESCRIPTION("Livepatch test: livepatch kprobed function"); Nit: The module adds a kprobe. I would invert the logic: MODULE_DESCRIPTION("Livepatch test: kprobe livepatched function"); Best Regards, Petr
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..fb7e9914f4a0 --- /dev/null +++ b/tools/testing/selftests/livepatch/test-kprobe.sh @@ -0,0 +1,65 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2024 SUSE +# Author: Michael Vetter <mvetter@suse.com> + +. $(dirname $0)/functions.sh + +MOD_LIVEPATCH=test_klp_livepatch +MOD_KPROBE=test_klp_kprobe + +setup_config + +# Kprobe a function and verify that we can't livepatch that same function +# when it uses a post_handler since only one IPMODIFY maybe be registered +# to any given function at a time. + +start_test "livepatch interaction with kprobed function with post_handler" + +STATE=$(cat /sys/kernel/debug/kprobes/enabled) +echo 1 > /sys/kernel/debug/kprobes/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" + +echo $STATE > /sys/kernel/debug/kprobes/enabled + +exit 0 diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile index e6e638c4bcba..4981d270f128 100644 --- a/tools/testing/selftests/livepatch/test_modules/Makefile +++ b/tools/testing/selftests/livepatch/test_modules/Makefile @@ -11,7 +11,8 @@ obj-m += test_klp_atomic_replace.o \ test_klp_state2.o \ test_klp_state3.o \ test_klp_shadow_vars.o \ - test_klp_syscall.o + test_klp_syscall.o \ + test_klp_kprobe.o # Ensure that KDIR exists, otherwise skip the compilation modules: 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..49b579ea1054 --- /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: livepatch 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. Signed-off-by: Michael Vetter <mvetter@suse.com> --- V2: Save and restore kprobe state. tools/testing/selftests/livepatch/Makefile | 3 +- .../selftests/livepatch/test-kprobe.sh | 65 +++++++++++++++++++ .../selftests/livepatch/test_modules/Makefile | 3 +- .../livepatch/test_modules/test_klp_kprobe.c | 38 +++++++++++ 4 files changed, 107 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