From patchwork Tue Jun 30 16:47:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 11634391 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9AD3013B6 for ; Tue, 30 Jun 2020 16:48:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BC4E20723 for ; Tue, 30 Jun 2020 16:48:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729500AbgF3QsS (ORCPT ); Tue, 30 Jun 2020 12:48:18 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52875 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728022AbgF3QsR (ORCPT ); Tue, 30 Jun 2020 12:48:17 -0400 Received: from 1.general.cascardo.us.vpn ([10.172.70.58] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jqJQc-0001jJ-S7; Tue, 30 Jun 2020 16:48:15 +0000 From: Thadeu Lima de Souza Cascardo To: linux-kselftest@vger.kernel.org Cc: Oleg Nesterov , Shuah Khan , linuxppc-dev@lists.ozlabs.org, Thadeu Lima de Souza Cascardo , Michael Ellerman , Kees Cook Subject: [PATCH] selftests/seccomp: fix ptrace tests on powerpc Date: Tue, 30 Jun 2020 13:47:39 -0300 Message-Id: <20200630164739.1268222-1-cascardo@canonical.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org As pointed out by Michael Ellerman, the ptrace ABI on powerpc does not allow or require the return code to be set on syscall entry when skipping the syscall. It will always return ENOSYS and the return code must be set on syscall exit. This code does that, behaving more similarly to strace. It still sets the return code on entry, which is overridden on powerpc, and it will always repeat the same on exit. Also, on powerpc, the errno is not inverted, and depends on ccr.so being set. This has been tested on powerpc and amd64. Cc: Michael Ellerman Cc: Kees Cook Signed-off-by: Thadeu Lima de Souza Cascardo --- tools/testing/selftests/seccomp/seccomp_bpf.c | 24 +++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 252140a52553..b90a9190ba88 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1738,6 +1738,14 @@ void change_syscall(struct __test_metadata *_metadata, TH_LOG("Can't modify syscall return on this architecture"); #else regs.SYSCALL_RET = result; +# if defined(__powerpc__) + if (result < 0) { + regs.SYSCALL_RET = -result; + regs.ccr |= 0x10000000; + } else { + regs.ccr &= ~0x10000000; + } +# endif #endif #ifdef HAVE_GETREGS @@ -1796,6 +1804,7 @@ void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee, int ret, nr; unsigned long msg; static bool entry; + int *syscall_nr = args; /* * The traditional way to tell PTRACE_SYSCALL entry/exit @@ -1809,10 +1818,15 @@ void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee, EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY : PTRACE_EVENTMSG_SYSCALL_EXIT, msg); - if (!entry) + if (!entry && !syscall_nr) return; - nr = get_syscall(_metadata, tracee); + if (entry) + nr = get_syscall(_metadata, tracee); + else + nr = *syscall_nr; + if (syscall_nr) + *syscall_nr = nr; if (nr == __NR_getpid) change_syscall(_metadata, tracee, __NR_getppid, 0); @@ -1889,9 +1903,10 @@ TEST_F(TRACE_syscall, ptrace_syscall_redirected) TEST_F(TRACE_syscall, ptrace_syscall_errno) { + int syscall_nr = -1; /* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */ teardown_trace_fixture(_metadata, self->tracer); - self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL, + self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, &syscall_nr, true); /* Tracer should skip the open syscall, resulting in ESRCH. */ @@ -1900,9 +1915,10 @@ TEST_F(TRACE_syscall, ptrace_syscall_errno) TEST_F(TRACE_syscall, ptrace_syscall_faked) { + int syscall_nr = -1; /* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */ teardown_trace_fixture(_metadata, self->tracer); - self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL, + self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, &syscall_nr, true); /* Tracer should skip the gettid syscall, resulting fake pid. */