From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3EE34C64E7B for ; Wed, 2 Dec 2020 14:13:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAB1821D7F for ; Wed, 2 Dec 2020 14:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730278AbgLBOMr (ORCPT ); Wed, 2 Dec 2020 09:12:47 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:34386 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730231AbgLBOMq (ORCPT ); Wed, 2 Dec 2020 09:12:46 -0500 Date: Wed, 02 Dec 2020 14:12:03 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1606918323; h=from:from:sender:sender:reply-to:reply-to:subject:subject: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=k9IqovZVw4VGuXlBGyr5hXucg+Y9C6lPnwxCVdzVLQ0=; b=wyR094j44uTZEL3OlJS3Bxq2j26q+fGdDiM0/ZWUJcF8s1O6J2c+U/Wyg31lsBGTsM0SpP OrHloXoK+k0Dp35QwIZbzpA98yAw0IDT/OSQCcgtP/TKixkGAbucTacxqm/ZtFtvYGWNlW 7NA3rZa5lSp+hy5KTx8R0yFfCaB8wVEfI9OT+vUWY7VmcG3GYpTf7KeP//uKtjmrvonJZa KibsTsy8p5t/FJwa5WX67Wx/55q9GYsTPJCTufuhNykKeXmPV+l8cVeM40P6TyaVtLi5EH pSScxiEzKhqmclaQeFO39UKu+Qd7J1oFUp0mR02mjgC3jO9+AfsCqNdSoirw4w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1606918323; h=from:from:sender:sender:reply-to:reply-to:subject:subject: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=k9IqovZVw4VGuXlBGyr5hXucg+Y9C6lPnwxCVdzVLQ0=; b=7DGV5tAHO3o3wOivi7HtqEKqxg+R0zlwp0ywsLv0n++jsNSbZdC7rrrw3vpfRz535DweQF A5HSPneQWUEuEjAA== From: "tip-bot2 for Gabriel Krisman Bertazi" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: core/entry] selftests: Add kselftest for syscall user dispatch Cc: Gabriel Krisman Bertazi , Thomas Gleixner , Andy Lutomirski , Kees Cook , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20201127193238.821364-6-krisman@collabora.com> References: <20201127193238.821364-6-krisman@collabora.com> MIME-Version: 1.0 Message-ID: <160691832303.3364.2481794720161260105.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the core/entry branch of tip: Commit-ID: 179ef035992e89646e17138b18b130bb874b86bb Gitweb: https://git.kernel.org/tip/179ef035992e89646e17138b18b130bb874b86bb Author: Gabriel Krisman Bertazi AuthorDate: Fri, 27 Nov 2020 14:32:36 -05:00 Committer: Thomas Gleixner CommitterDate: Wed, 02 Dec 2020 15:07:56 +01:00 selftests: Add kselftest for syscall user dispatch Implement functionality tests for syscall user dispatch. In order to make the test portable, refrain from open coding syscall dispatchers and calculating glibc memory ranges. Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Acked-by: Kees Cook Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20201127193238.821364-6-krisman@collabora.com --- tools/testing/selftests/Makefile | 1 +- tools/testing/selftests/syscall_user_dispatch/.gitignore | 3 +- tools/testing/selftests/syscall_user_dispatch/Makefile | 9 +- tools/testing/selftests/syscall_user_dispatch/config | 1 +- tools/testing/selftests/syscall_user_dispatch/sud_test.c | 310 +++++++- 5 files changed, 324 insertions(+) create mode 100644 tools/testing/selftests/syscall_user_dispatch/.gitignore create mode 100644 tools/testing/selftests/syscall_user_dispatch/Makefile create mode 100644 tools/testing/selftests/syscall_user_dispatch/config create mode 100644 tools/testing/selftests/syscall_user_dispatch/sud_test.c diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index d9c2835..96d5682 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -56,6 +56,7 @@ TARGETS += sparc64 TARGETS += splice TARGETS += static_keys TARGETS += sync +TARGETS += syscall_user_dispatch TARGETS += sysctl TARGETS += tc-testing TARGETS += timens diff --git a/tools/testing/selftests/syscall_user_dispatch/.gitignore b/tools/testing/selftests/syscall_user_dispatch/.gitignore new file mode 100644 index 0000000..f539615 --- /dev/null +++ b/tools/testing/selftests/syscall_user_dispatch/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only +sud_test +sud_benchmark diff --git a/tools/testing/selftests/syscall_user_dispatch/Makefile b/tools/testing/selftests/syscall_user_dispatch/Makefile new file mode 100644 index 0000000..8e15fa4 --- /dev/null +++ b/tools/testing/selftests/syscall_user_dispatch/Makefile @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0 +top_srcdir = ../../../.. +INSTALL_HDR_PATH = $(top_srcdir)/usr +LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/ + +CFLAGS += -Wall -I$(LINUX_HDR_PATH) + +TEST_GEN_PROGS := sud_test +include ../lib.mk diff --git a/tools/testing/selftests/syscall_user_dispatch/config b/tools/testing/selftests/syscall_user_dispatch/config new file mode 100644 index 0000000..039e303 --- /dev/null +++ b/tools/testing/selftests/syscall_user_dispatch/config @@ -0,0 +1 @@ +CONFIG_GENERIC_ENTRY=y diff --git a/tools/testing/selftests/syscall_user_dispatch/sud_test.c b/tools/testing/selftests/syscall_user_dispatch/sud_test.c new file mode 100644 index 0000000..6498b05 --- /dev/null +++ b/tools/testing/selftests/syscall_user_dispatch/sud_test.c @@ -0,0 +1,310 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2020 Collabora Ltd. + * + * Test code for syscall user dispatch + */ + +#define _GNU_SOURCE +#include +#include +#include +#include + +#include +#include "../kselftest_harness.h" + +#ifndef PR_SET_SYSCALL_USER_DISPATCH +# define PR_SET_SYSCALL_USER_DISPATCH 59 +# define PR_SYS_DISPATCH_OFF 0 +# define PR_SYS_DISPATCH_ON 1 +#endif + +#ifndef SYS_USER_DISPATCH +# define SYS_USER_DISPATCH 2 +#endif + +#ifdef __NR_syscalls +# define MAGIC_SYSCALL_1 (__NR_syscalls + 1) /* Bad Linux syscall number */ +#else +# define MAGIC_SYSCALL_1 (0xff00) /* Bad Linux syscall number */ +#endif + +#define SYSCALL_DISPATCH_ON(x) ((x) = 1) +#define SYSCALL_DISPATCH_OFF(x) ((x) = 0) + +/* Test Summary: + * + * - dispatch_trigger_sigsys: Verify if PR_SET_SYSCALL_USER_DISPATCH is + * able to trigger SIGSYS on a syscall. + * + * - bad_selector: Test that a bad selector value triggers SIGSYS with + * si_errno EINVAL. + * + * - bad_prctl_param: Test that the API correctly rejects invalid + * parameters on prctl + * + * - dispatch_and_return: Test that a syscall is selectively dispatched + * to userspace depending on the value of selector. + * + * - disable_dispatch: Test that the PR_SYS_DISPATCH_OFF correctly + * disables the dispatcher + * + * - direct_dispatch_range: Test that a syscall within the allowed range + * can bypass the dispatcher. + */ + +TEST_SIGNAL(dispatch_trigger_sigsys, SIGSYS) +{ + char sel = 0; + struct sysinfo info; + int ret; + + ret = sysinfo(&info); + ASSERT_EQ(0, ret); + + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &sel); + ASSERT_EQ(0, ret) { + TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH"); + } + + SYSCALL_DISPATCH_ON(sel); + + sysinfo(&info); + + EXPECT_FALSE(true) { + TH_LOG("Unreachable!"); + } +} + +TEST(bad_prctl_param) +{ + char sel = 0; + int op; + + /* Invalid op */ + op = -1; + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0, 0, &sel); + ASSERT_EQ(EINVAL, errno); + + /* PR_SYS_DISPATCH_OFF */ + op = PR_SYS_DISPATCH_OFF; + + /* offset != 0 */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, 0); + EXPECT_EQ(EINVAL, errno); + + /* len != 0 */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0xff, 0); + EXPECT_EQ(EINVAL, errno); + + /* sel != NULL */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, &sel); + EXPECT_EQ(EINVAL, errno); + + /* Valid parameter */ + errno = 0; + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, 0x0); + EXPECT_EQ(0, errno); + + /* PR_SYS_DISPATCH_ON */ + op = PR_SYS_DISPATCH_ON; + + /* Dispatcher region is bad (offset > 0 && len == 0) */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, &sel); + EXPECT_EQ(EINVAL, errno); + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, -1L, 0x0, &sel); + EXPECT_EQ(EINVAL, errno); + + /* Invalid selector */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x1, (void *) -1); + ASSERT_EQ(EFAULT, errno); + + /* + * Dispatcher range overflows unsigned long + */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 1, -1L, &sel); + ASSERT_EQ(EINVAL, errno) { + TH_LOG("Should reject bad syscall range"); + } + + /* + * Allowed range overflows usigned long + */ + prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, -1L, 0x1, &sel); + ASSERT_EQ(EINVAL, errno) { + TH_LOG("Should reject bad syscall range"); + } +} + +/* + * Use global selector for handle_sigsys tests, to avoid passing + * selector to signal handler + */ +char glob_sel; +int nr_syscalls_emulated; +int si_code; +int si_errno; + +static void handle_sigsys(int sig, siginfo_t *info, void *ucontext) +{ + si_code = info->si_code; + si_errno = info->si_errno; + + if (info->si_syscall == MAGIC_SYSCALL_1) + nr_syscalls_emulated++; + + /* In preparation for sigreturn. */ + SYSCALL_DISPATCH_OFF(glob_sel); +} + +TEST(dispatch_and_return) +{ + long ret; + struct sigaction act; + sigset_t mask; + + glob_sel = 0; + nr_syscalls_emulated = 0; + si_code = 0; + si_errno = 0; + + memset(&act, 0, sizeof(act)); + sigemptyset(&mask); + + act.sa_sigaction = handle_sigsys; + act.sa_flags = SA_SIGINFO; + act.sa_mask = mask; + + ret = sigaction(SIGSYS, &act, NULL); + ASSERT_EQ(0, ret); + + /* Make sure selector is good prior to prctl. */ + SYSCALL_DISPATCH_OFF(glob_sel); + + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &glob_sel); + ASSERT_EQ(0, ret) { + TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH"); + } + + /* MAGIC_SYSCALL_1 doesn't exist. */ + SYSCALL_DISPATCH_OFF(glob_sel); + ret = syscall(MAGIC_SYSCALL_1); + EXPECT_EQ(-1, ret) { + TH_LOG("Dispatch triggered unexpectedly"); + } + + /* MAGIC_SYSCALL_1 should be emulated. */ + nr_syscalls_emulated = 0; + SYSCALL_DISPATCH_ON(glob_sel); + + ret = syscall(MAGIC_SYSCALL_1); + EXPECT_EQ(MAGIC_SYSCALL_1, ret) { + TH_LOG("Failed to intercept syscall"); + } + EXPECT_EQ(1, nr_syscalls_emulated) { + TH_LOG("Failed to emulate syscall"); + } + ASSERT_EQ(SYS_USER_DISPATCH, si_code) { + TH_LOG("Bad si_code in SIGSYS"); + } + ASSERT_EQ(0, si_errno) { + TH_LOG("Bad si_errno in SIGSYS"); + } +} + +TEST_SIGNAL(bad_selector, SIGSYS) +{ + long ret; + struct sigaction act; + sigset_t mask; + struct sysinfo info; + + glob_sel = 0; + nr_syscalls_emulated = 0; + si_code = 0; + si_errno = 0; + + memset(&act, 0, sizeof(act)); + sigemptyset(&mask); + + act.sa_sigaction = handle_sigsys; + act.sa_flags = SA_SIGINFO; + act.sa_mask = mask; + + ret = sigaction(SIGSYS, &act, NULL); + ASSERT_EQ(0, ret); + + /* Make sure selector is good prior to prctl. */ + SYSCALL_DISPATCH_OFF(glob_sel); + + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &glob_sel); + ASSERT_EQ(0, ret) { + TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH"); + } + + glob_sel = -1; + + sysinfo(&info); + + /* Even though it is ready to catch SIGSYS, the signal is + * supposed to be uncatchable. + */ + + EXPECT_FALSE(true) { + TH_LOG("Unreachable!"); + } +} + +TEST(disable_dispatch) +{ + int ret; + struct sysinfo info; + char sel = 0; + + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, 0, &sel); + ASSERT_EQ(0, ret) { + TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH"); + } + + /* MAGIC_SYSCALL_1 doesn't exist. */ + SYSCALL_DISPATCH_OFF(glob_sel); + + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_OFF, 0, 0, 0); + EXPECT_EQ(0, ret) { + TH_LOG("Failed to unset syscall user dispatch"); + } + + /* Shouldn't have any effect... */ + SYSCALL_DISPATCH_ON(glob_sel); + + ret = syscall(__NR_sysinfo, &info); + EXPECT_EQ(0, ret) { + TH_LOG("Dispatch triggered unexpectedly"); + } +} + +TEST(direct_dispatch_range) +{ + int ret = 0; + struct sysinfo info; + char sel = 0; + + /* + * Instead of calculating libc addresses; allow the entire + * memory map and lock the selector. + */ + ret = prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 0, -1L, &sel); + ASSERT_EQ(0, ret) { + TH_LOG("Kernel does not support CONFIG_SYSCALL_USER_DISPATCH"); + } + + SYSCALL_DISPATCH_ON(sel); + + ret = sysinfo(&info); + ASSERT_EQ(0, ret) { + TH_LOG("Dispatch triggered unexpectedly"); + } +} + +TEST_HARNESS_MAIN