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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D682C433FE for ; Mon, 14 Feb 2022 10:41:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349311AbiBNKlG (ORCPT ); Mon, 14 Feb 2022 05:41:06 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:48568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349832AbiBNKgo (ORCPT ); Mon, 14 Feb 2022 05:36:44 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E38713700B; Mon, 14 Feb 2022 02:03:07 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 85878B80D6D; Mon, 14 Feb 2022 10:03:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C7DBC340E9; Mon, 14 Feb 2022 10:03:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644832985; bh=OjPeCyA/ofgU7GFCY7rViE5BCiYYQglG21UC4UdiCZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ruk590Jw7rtS3Fw8vK056fgSn+lLCut6wxzaHgBAvupUuCEbuW8bW7gbH+yxbkeJY d3wMyVL5hE/QIJAKKFPCcJe5hrbeRBWs+NX9/omCU45Kl8l3MpIxz8R8Y4aR9KXgKg ylR/QGY8Y8Z6kWNTc6xVeaNdPClD7mbf1+PkzfiI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Will Drewry , Kees Cook Subject: [PATCH 5.16 188/203] seccomp: Invalidate seccomp mode to catch death failures Date: Mon, 14 Feb 2022 10:27:12 +0100 Message-Id: <20220214092516.637946967@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092510.221474733@linuxfoundation.org> References: <20220214092510.221474733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kees Cook commit 495ac3069a6235bfdf516812a2a9b256671bbdf9 upstream. If seccomp tries to kill a process, it should never see that process again. To enforce this proactively, switch the mode to something impossible. If encountered: WARN, reject all syscalls, and attempt to kill the process again even harder. Cc: Andy Lutomirski Cc: Will Drewry Fixes: 8112c4f140fa ("seccomp: remove 2-phase API") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- kernel/seccomp.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -29,6 +29,9 @@ #include #include +/* Not exposed in headers: strictly internal use only. */ +#define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1) + #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER #include #endif @@ -1010,6 +1013,7 @@ static void __secure_computing_strict(in #ifdef SECCOMP_DEBUG dump_stack(); #endif + current->seccomp.mode = SECCOMP_MODE_DEAD; seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true); do_exit(SIGKILL); } @@ -1261,6 +1265,7 @@ static int __seccomp_filter(int this_sys case SECCOMP_RET_KILL_THREAD: case SECCOMP_RET_KILL_PROCESS: default: + current->seccomp.mode = SECCOMP_MODE_DEAD; seccomp_log(this_syscall, SIGSYS, action, true); /* Dump core only if this is the last remaining thread. */ if (action != SECCOMP_RET_KILL_THREAD || @@ -1309,6 +1314,11 @@ int __secure_computing(const struct secc return 0; case SECCOMP_MODE_FILTER: return __seccomp_filter(this_syscall, sd, false); + /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */ + case SECCOMP_MODE_DEAD: + WARN_ON_ONCE(1); + do_exit(SIGKILL); + return -1; default: BUG(); }