From patchwork Fri Sep 4 20:31:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriel Krisman Bertazi X-Patchwork-Id: 11758537 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 B469A14F9 for ; Fri, 4 Sep 2020 20:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A462B208FE for ; Fri, 4 Sep 2020 20:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728171AbgIDUcS (ORCPT ); Fri, 4 Sep 2020 16:32:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726621AbgIDUcR (ORCPT ); Fri, 4 Sep 2020 16:32:17 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BABD6C061244; Fri, 4 Sep 2020 13:32:16 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id 6224429B031 From: Gabriel Krisman Bertazi To: luto@kernel.org, tglx@linutronix.de, keescook@chromium.org Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, willy@infradead.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, Gabriel Krisman Bertazi , kernel@collabora.com Subject: [PATCH v6 6/9] kernel: entry: Support Syscall User Dispatch for common syscall entry Date: Fri, 4 Sep 2020 16:31:44 -0400 Message-Id: <20200904203147.2908430-7-krisman@collabora.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200904203147.2908430-1-krisman@collabora.com> References: <20200904203147.2908430-1-krisman@collabora.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Syscall User Dispatch (SUD) must take precedence over seccomp, since the use case is emulation (it can be invoked with a different ABI) such that seccomp filtering by syscall number doesn't make sense in the first place. In addition, either the syscall is dispatched back to userspace, in which case there is no resource for seccomp to protect, or the syscall will be executed, and seccomp will execute next. Regarding ptrace, I experimented with before and after, and while the same ABI argument applies, I felt it was easier to debug if I let ptrace happen for syscalls that are dispatched back to userspace. In addition, doing it after ptrace makes the code in syscall_exit_work slightly simpler, since it doesn't require special handling for this feature. Signed-off-by: Gabriel Krisman Bertazi --- kernel/entry/common.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 44fd089d59da..fdb0c543539d 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -6,6 +6,8 @@ #include #include +#include "common.h" + #define CREATE_TRACE_POINTS #include @@ -47,6 +49,12 @@ static inline long do_syscall_intercept(struct pt_regs *regs) int sysint_work = READ_ONCE(current->syscall_intercept); int ret; + if (sysint_work & SYSINT_USER_DISPATCH) { + ret = do_syscall_user_dispatch(regs); + if (ret == -1L) + return ret; + } + if (sysint_work & SYSINT_SECCOMP) { ret = __secure_computing(NULL); if (ret == -1L)