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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 07514C5DF63 for ; Wed, 6 Nov 2019 20:57:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5E9E217F5 for ; Wed, 6 Nov 2019 20:57:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732642AbfKFU5C (ORCPT ); Wed, 6 Nov 2019 15:57:02 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:45296 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732167AbfKFU4u (ORCPT ); Wed, 6 Nov 2019 15:56:50 -0500 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1iSSMB-00033W-UG; Wed, 06 Nov 2019 21:56:48 +0100 Message-Id: <20191106202806.611930277@linutronix.de> User-Agent: quilt/0.65 Date: Wed, 06 Nov 2019 20:35:08 +0100 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Stephen Hemminger , Willy Tarreau , Juergen Gross , Sean Christopherson , Linus Torvalds , "H. Peter Anvin" Subject: [patch 9/9] selftests/x86/iopl: Verify that CLI/STI result in #GP References: <20191106193459.581614484@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add tests that the now emulated iopl() functionality does not longer allow user space to disable interrupts. Signed-off-by: Thomas Gleixner --- tools/testing/selftests/x86/iopl.c | 104 +++++++++++++++++++++++++++++++++---- 1 file changed, 93 insertions(+), 11 deletions(-) --- a/tools/testing/selftests/x86/iopl.c +++ b/tools/testing/selftests/x86/iopl.c @@ -35,6 +35,16 @@ static void sethandler(int sig, void (*h } +static void clearhandler(int sig) +{ + struct sigaction sa; + memset(&sa, 0, sizeof(sa)); + sa.sa_handler = SIG_DFL; + sigemptyset(&sa.sa_mask); + if (sigaction(sig, &sa, 0)) + err(1, "sigaction"); +} + static jmp_buf jmpbuf; static void sigsegv(int sig, siginfo_t *si, void *ctx_void) @@ -42,22 +52,100 @@ static void sigsegv(int sig, siginfo_t * siglongjmp(jmpbuf, 1); } +static bool try_outb(unsigned short port) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("outb %%al, %w[port]" + : : [port] "Nd" (port), "a" (0)); + return true; + } + clearhandler(SIGSEGV); +} + +static void expect_gp_outb(unsigned short port) +{ + if (try_outb(port)) { + printf("[FAIL]\toutb to 0x%02hx worked\n", port); + nerrs++; + } + + printf("[OK]\toutb to 0x%02hx failed\n", port); +} + +static bool try_cli(void) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("cli"); + return true; + } + clearhandler(SIGSEGV); +} + +static bool try_sti(void) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("sti"); + return true; + } + clearhandler(SIGSEGV); +} + +static void expect_gp_sti(void) +{ + if (try_sti()) { + printf("[FAIL]\tSTI worked\n"); + nerrs++; + } else { + printf("[OK]\tSTI faulted\n"); + } +} + +static void expect_gp_cli(void) +{ + if (try_cli()) { + printf("[FAIL]\tCLI worked\n"); + nerrs++; + } else { + printf("[OK]\tCLI faulted\n"); + } +} + int main(void) { cpu_set_t cpuset; + CPU_ZERO(&cpuset); CPU_SET(0, &cpuset); if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) err(1, "sched_setaffinity to CPU 0"); /* Probe for iopl support. Note that iopl(0) works even as nonroot. */ - if (iopl(3) != 0) { + switch(iopl(3)) { + case 0: + break; + case -ENOSYS: + printf("[OK]\tiopl() nor supported\n"); + return 0; + default: printf("[OK]\tiopl(3) failed (%d) -- try running as root\n", errno); return 0; } - /* Restore our original state prior to starting the test. */ + /* Make sure that CLI/STI are blocked even with IOPL level 3 */ + expect_gp_cli(); + expect_gp_sti(); + + /* Restore our original state prior to starting the fork test. */ if (iopl(0) != 0) err(1, "iopl(0)"); @@ -90,14 +178,9 @@ int main(void) printf("[RUN]\tparent: write to 0x80 (should fail)\n"); - sethandler(SIGSEGV, sigsegv, 0); - if (sigsetjmp(jmpbuf, 1) != 0) { - printf("[OK]\twrite was denied\n"); - } else { - asm volatile ("outb %%al, $0x80" : : "a" (0)); - printf("[FAIL]\twrite was allowed\n"); - nerrs++; - } + expect_gp_outb(0x80); + expect_gp_cli(); + expect_gp_sti(); /* Test the capability checks. */ printf("\tiopl(3)\n"); @@ -133,4 +216,3 @@ int main(void) done: return nerrs ? 1 : 0; } -