From patchwork Tue Oct 31 21:10:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcos Paulo de Souza X-Patchwork-Id: 13442282 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54AD5C41535 for ; Tue, 31 Oct 2023 21:11:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344791AbjJaVL2 (ORCPT ); Tue, 31 Oct 2023 17:11:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344909AbjJaVL0 (ORCPT ); Tue, 31 Oct 2023 17:11:26 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFE68115; Tue, 31 Oct 2023 14:11:23 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 7DAF821A85; Tue, 31 Oct 2023 21:11:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1698786682; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YWFVODM4L9r3H5eDf/XnrPEj/bstgrOYhDzRCk+s4bA=; b=pkhLf6OQMHUKBRE97JdtuK1eC3ltvkvcU9D0aX5ISYMxQverONZ25L/FHbwNFVxq8OnYVf NxkiheKbmT3T05LcPlcZwT/fZkxPNK4VaxF7tFsqvIpzbLZ+XtjHUEgfXQ2mtyPC0IJkR0 QyUmasK8efV8mGhomww2GWHvcopuDag= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 079F2138EF; Tue, 31 Oct 2023 21:11:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id /BuDL3ltQWXnWgAAMHmgww (envelope-from ); Tue, 31 Oct 2023 21:11:21 +0000 From: Marcos Paulo de Souza Date: Tue, 31 Oct 2023 18:10:53 -0300 Subject: [PATCH v3 3/3] selftests: livepatch: Test livepatching a heavily called syscall MIME-Version: 1.0 Message-Id: <20231031-send-lp-kselftests-v3-3-2b1655c2605f@suse.com> References: <20231031-send-lp-kselftests-v3-0-2b1655c2605f@suse.com> In-Reply-To: <20231031-send-lp-kselftests-v3-0-2b1655c2605f@suse.com> To: Shuah Khan , Jonathan Corbet , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence Cc: linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, live-patching@vger.kernel.org, Marcos Paulo de Souza X-Mailer: b4 0.12.1 X-Developer-Signature: v=1; a=ed25519-sha256; t=1698786668; l=8723; i=mpdesouza@suse.com; s=20231031; h=from:subject:message-id; bh=b5alYQkuOfzrRyAofNX67gkTWpNDU3R7ywSH8MEJOJw=; b=Y/c4XFn5/DNnfD+A2NRd7SogxPW1b2FAVd+5f/nyOQga2n13FnB8BjpD4WmW2TkeL9AeUp36em2r ADlmfPecALcVfTV2J55tvrKqGZPULrgIggdl3jZ+qD8Wx4B5kwf2 X-Developer-Key: i=mpdesouza@suse.com; a=ed25519; pk=/Ni/TsKkr69EOmdZXkp1Q/BlzDonbOBRsfPa18ySIwU= Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The test proves that a syscall can be livepatched. It is interesting because syscalls are called a tricky way. Also the process gets livepatched either when sleeping in the userspace or when entering or leaving the kernel space. The livepatch is a bit tricky: 1. The syscall function name is architecture specific. Also ARCH_HAS_SYSCALL_WRAPPER must be taken in account. 2. The syscall must stay working the same way for other processes on the system. It is solved by decrementing a counter only for PIDs of the test processes. It means that the test processes has to call the livepatched syscall at least once. The test creates one userspace process per online cpu. The processes are calling getpid in a busy loop. The intention is to create random locations when the livepatch gets enabled. Nothing is guarantted. The magic is in the randomness. Signed-off-by: Marcos Paulo de Souza --- tools/testing/selftests/livepatch/Makefile | 4 +- tools/testing/selftests/livepatch/test-syscall.sh | 53 ++++++++++ .../selftests/livepatch/test_klp-call_getpid.c | 44 ++++++++ .../selftests/livepatch/test_modules/Makefile | 3 +- .../livepatch/test_modules/test_klp_syscall.c | 116 +++++++++++++++++++++ 5 files changed, 218 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/livepatch/Makefile b/tools/testing/selftests/livepatch/Makefile index 119e2bbebe5d..35418a4790be 100644 --- a/tools/testing/selftests/livepatch/Makefile +++ b/tools/testing/selftests/livepatch/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0 +TEST_GEN_FILES := test_klp-call_getpid TEST_GEN_MODS_DIR := test_modules TEST_PROGS_EXTENDED := functions.sh TEST_PROGS := \ @@ -8,7 +9,8 @@ TEST_PROGS := \ test-shadow-vars.sh \ test-state.sh \ test-ftrace.sh \ - test-sysfs.sh + test-sysfs.sh \ + test-syscall.sh TEST_FILES := settings diff --git a/tools/testing/selftests/livepatch/test-syscall.sh b/tools/testing/selftests/livepatch/test-syscall.sh new file mode 100755 index 000000000000..b76a881d4013 --- /dev/null +++ b/tools/testing/selftests/livepatch/test-syscall.sh @@ -0,0 +1,53 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2023 SUSE +# Author: Marcos Paulo de Souza + +. $(dirname $0)/functions.sh + +MOD_SYSCALL=test_klp_syscall + +setup_config + +# - Start _NRPROC processes calling getpid and load a livepatch to patch the +# getpid syscall. Check if all the processes transitioned to the livepatched +# state. + +start_test "patch getpid syscall while being heavily hammered" + +for i in $(seq 1 $(getconf _NPROCESSORS_ONLN)); do + ./test_klp-call_getpid & + pids[$i]="$!" +done + +pid_list=$(echo ${pids[@]} | tr ' ' ',') +load_lp $MOD_SYSCALL klp_pids=$pid_list + +# wait for all tasks to transition to patched state +loop_until 'grep -q '^0$' /sys/kernel/test_klp_syscall/npids' + +pending_pids=$(cat /sys/kernel/test_klp_syscall/npids) +log "$MOD_SYSCALL: Remaining not livepatched processes: $pending_pids" + +for pid in ${pids[@]}; do + kill $pid || true +done + +disable_lp $MOD_SYSCALL +unload_lp $MOD_SYSCALL + +check_result "% insmod test_modules/$MOD_SYSCALL.ko klp_pids=$pid_list +livepatch: enabling patch '$MOD_SYSCALL' +livepatch: '$MOD_SYSCALL': initializing patching transition +livepatch: '$MOD_SYSCALL': starting patching transition +livepatch: '$MOD_SYSCALL': completing patching transition +livepatch: '$MOD_SYSCALL': patching complete +$MOD_SYSCALL: Remaining not livepatched processes: 0 +% echo 0 > /sys/kernel/livepatch/$MOD_SYSCALL/enabled +livepatch: '$MOD_SYSCALL': initializing unpatching transition +livepatch: '$MOD_SYSCALL': starting unpatching transition +livepatch: '$MOD_SYSCALL': completing unpatching transition +livepatch: '$MOD_SYSCALL': unpatching complete +% rmmod $MOD_SYSCALL" + +exit 0 diff --git a/tools/testing/selftests/livepatch/test_klp-call_getpid.c b/tools/testing/selftests/livepatch/test_klp-call_getpid.c new file mode 100644 index 000000000000..ce321a2d7308 --- /dev/null +++ b/tools/testing/selftests/livepatch/test_klp-call_getpid.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2023 SUSE + * Authors: Libor Pechacek + * Marcos Paulo de Souza + */ + +#include +#include +#include +#include +#include + +static int stop; +static int sig_int; + +void hup_handler(int signum) +{ + stop = 1; +} + +void int_handler(int signum) +{ + stop = 1; + sig_int = 1; +} + +int main(int argc, char *argv[]) +{ + long count = 0; + + signal(SIGHUP, &hup_handler); + signal(SIGINT, &int_handler); + + while (!stop) { + (void)syscall(SYS_getpid); + count++; + } + + if (sig_int) + printf("%ld iterations done\n", count); + + return 0; +} diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile index 6f7c2103d27d..f5e880269bff 100644 --- a/tools/testing/selftests/livepatch/test_modules/Makefile +++ b/tools/testing/selftests/livepatch/test_modules/Makefile @@ -10,7 +10,8 @@ obj-m += test_klp_atomic_replace.o \ test_klp_state.o \ test_klp_state2.o \ test_klp_state3.o \ - test_klp_shadow_vars.o + test_klp_shadow_vars.o \ + test_klp_syscall.o modules: $(Q)$(MAKE) -C $(KDIR) modules KBUILD_EXTMOD=$(TESTMODS_DIR) diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c new file mode 100644 index 000000000000..619496cc3481 --- /dev/null +++ b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017-2023 SUSE + * Authors: Libor Pechacek + * Nicolai Stange + * Marcos Paulo de Souza + */ + +#include +#include +#include +#include +#include + +#if defined(__x86_64__) +#define FN_PREFIX __x64_ +#elif defined(__s390x__) +#define FN_PREFIX __s390x_ +#elif defined(__aarch64__) +#define FN_PREFIX __arm64_ +#else +/* powerpc does not select ARCH_HAS_SYSCALL_WRAPPER */ +#define FN_PREFIX +#endif + +/* Protects klp_pids */ +static DEFINE_MUTEX(kpid_mutex); + +static unsigned int npids, npids_pending; +static int klp_pids[NR_CPUS]; +module_param_array(klp_pids, int, &npids_pending, 0); +MODULE_PARM_DESC(klp_pids, "Array of pids to be transitioned to livepatched state."); + +static ssize_t npids_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", npids_pending); +} + +static struct kobj_attribute klp_attr = __ATTR_RO(npids); +static struct kobject *klp_kobj; + +asmlinkage long lp_sys_getpid(void) +{ + int i; + + mutex_lock(&kpid_mutex); + if (npids_pending > 0) { + for (i = 0; i < npids; i++) { + if (current->pid == klp_pids[i]) { + klp_pids[i] = 0; + npids_pending--; + break; + } + } + } + mutex_unlock(&kpid_mutex); + + return task_tgid_vnr(current); +} + +static struct klp_func vmlinux_funcs[] = { + { + .old_name = __stringify(FN_PREFIX) "sys_getpid", + .new_func = lp_sys_getpid, + }, {} +}; + +static struct klp_object objs[] = { + { + /* name being NULL means vmlinux */ + .funcs = vmlinux_funcs, + }, {} +}; + +static struct klp_patch patch = { + .mod = THIS_MODULE, + .objs = objs, +}; + +static int livepatch_init(void) +{ + int ret; + + klp_kobj = kobject_create_and_add("test_klp_syscall", kernel_kobj); + if (!klp_kobj) + return -ENOMEM; + + ret = sysfs_create_file(klp_kobj, &klp_attr.attr); + if (ret) { + kobject_put(klp_kobj); + return ret; + } + + /* + * Save the number pids to transition to livepatched state before the + * number of pending pids is decremented. + */ + npids = npids_pending; + + return klp_enable_patch(&patch); +} + +static void livepatch_exit(void) +{ + kobject_put(klp_kobj); +} + +module_init(livepatch_init); +module_exit(livepatch_exit); +MODULE_LICENSE("GPL"); +MODULE_INFO(livepatch, "Y"); +MODULE_AUTHOR("Libor Pechacek "); +MODULE_AUTHOR("Nicolai Stange "); +MODULE_AUTHOR("Marcos Paulo de Souza "); +MODULE_DESCRIPTION("Livepatch test: syscall transition");