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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 4C4B7C2BC11 for ; Tue, 8 Sep 2020 20:22:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 132BA20936 for ; Tue, 8 Sep 2020 20:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730064AbgIHUWE (ORCPT ); Tue, 8 Sep 2020 16:22:04 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:54167 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729037AbgIHUWA (ORCPT ); Tue, 8 Sep 2020 16:22:00 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kFk7h-0007qP-BQ; Tue, 08 Sep 2020 20:21:49 +0000 Date: Tue, 8 Sep 2020 22:21:48 +0200 From: Christian Brauner To: Kees Cook Cc: Rich Felker , Kyle Huey , Robert O'Callahan , Christian Brauner , Andy Lutomirski , Will Drewry , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] selftests/seccomp: Add test for unknown SECCOMP_RET kill behavior Message-ID: <20200908202148.hiuqdbxzdjyrco2k@wittgenstein> References: <202009081232.92206075F7@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <202009081232.92206075F7@keescook> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 08, 2020 at 12:35:18PM -0700, Kees Cook wrote: > While we testing for the behavior of unknown seccomp filter return s/we/we're/ > values, there was no test for how it acted in a thread group. Add > a test in the thread group tests for this. > > Signed-off-by: Kees Cook > --- > (This is going via the seccomp tree.) > --- Thanks! Acked-by: Christian Brauner > tools/testing/selftests/seccomp/seccomp_bpf.c | 43 ++++++++++++++++--- > 1 file changed, 37 insertions(+), 6 deletions(-) > > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > index 7a6d40286a42..bfb382580493 100644 > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > @@ -774,8 +774,15 @@ void *kill_thread(void *data) > return (void *)SIBLING_EXIT_UNKILLED; > } > > +enum kill_t { > + KILL_THREAD, > + KILL_PROCESS, > + RET_UNKNOWN > +}; > + > /* Prepare a thread that will kill itself or both of us. */ > -void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process) > +void kill_thread_or_group(struct __test_metadata *_metadata, > + enum kill_t kill_how) > { > pthread_t thread; > void *status; > @@ -791,11 +798,12 @@ void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process) > .len = (unsigned short)ARRAY_SIZE(filter_thread), > .filter = filter_thread, > }; > + int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA; > struct sock_filter filter_process[] = { > BPF_STMT(BPF_LD|BPF_W|BPF_ABS, > offsetof(struct seccomp_data, nr)), > BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_prctl, 0, 1), > - BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL_PROCESS), > + BPF_STMT(BPF_RET|BPF_K, kill), > BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW), > }; > struct sock_fprog prog_process = { > @@ -808,13 +816,15 @@ void kill_thread_or_group(struct __test_metadata *_metadata, bool kill_process) > } > > ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, > - kill_process ? &prog_process : &prog_thread)); > + kill_how == KILL_THREAD ? &prog_thread > + : &prog_process)); > > /* > * Add the KILL_THREAD rule again to make sure that the KILL_PROCESS > * flag cannot be downgraded by a new filter. > */ > - ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread)); > + if (kill_how == KILL_PROCESS) > + ASSERT_EQ(0, seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog_thread)); (Ok, meaning that you still need to observe that the thread-group gets taken down not just a single thread.) > > /* Start a thread that will exit immediately. */ > ASSERT_EQ(0, pthread_create(&thread, NULL, kill_thread, (void *)false)); > @@ -842,7 +852,7 @@ TEST(KILL_thread) > child_pid = fork(); > ASSERT_LE(0, child_pid); > if (child_pid == 0) { > - kill_thread_or_group(_metadata, false); > + kill_thread_or_group(_metadata, KILL_THREAD); > _exit(38); > } > > @@ -861,7 +871,7 @@ TEST(KILL_process) > child_pid = fork(); > ASSERT_LE(0, child_pid); > if (child_pid == 0) { > - kill_thread_or_group(_metadata, true); > + kill_thread_or_group(_metadata, KILL_PROCESS); > _exit(38); > } > > @@ -872,6 +882,27 @@ TEST(KILL_process) > ASSERT_EQ(SIGSYS, WTERMSIG(status)); > } > > +TEST(KILL_unknown) > +{ > + int status; > + pid_t child_pid; > + > + child_pid = fork(); > + ASSERT_LE(0, child_pid); > + if (child_pid == 0) { > + kill_thread_or_group(_metadata, RET_UNKNOWN); > + _exit(38); > + } > + > + ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0)); > + > + /* If the entire process was killed, we'll see SIGSYS. */ > + EXPECT_TRUE(WIFSIGNALED(status)) { > + TH_LOG("Unknown SECCOMP_RET is only killing the thread?"); > + } > + ASSERT_EQ(SIGSYS, WTERMSIG(status)); > +} > + > /* TODO(wad) add 64-bit versus 32-bit arg tests. */ > TEST(arg_out_of_range) > { > -- > 2.25.1 > > > -- > Kees Cook