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 B552CC43219 for ; Mon, 14 Feb 2022 09:33:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243912AbiBNJd1 (ORCPT ); Mon, 14 Feb 2022 04:33:27 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:41364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243865AbiBNJdN (ORCPT ); Mon, 14 Feb 2022 04:33:13 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 742A260D90; Mon, 14 Feb 2022 01:31:38 -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 26D8FB80DCC; Mon, 14 Feb 2022 09:31:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B360C340E9; Mon, 14 Feb 2022 09:31:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644831096; bh=uevaLRTtbu0gQTNmH5s19jDCZEKQ+0PLVKpDgPs9ZbU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dBqfFpXMTV6Ae2mCOYkB2i7y1jV7VdyB6wPH/yeFSXLDlnOpqB63eMI55f2V3C+Hn 4ehUVxpHrrmhWoOl5ybaI59VCl9U6XI+sPOnEUnKUmh9auMBzyMUrUrGyRPulDdXTj 5w7gMaCvHPu9NiDJPNa2pW9+5P1zzwY49o3HJJoY= 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 4.14 42/44] seccomp: Invalidate seccomp mode to catch death failures Date: Mon, 14 Feb 2022 10:26:05 +0100 Message-Id: <20220214092449.263018817@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092447.897544753@linuxfoundation.org> References: <20220214092447.897544753@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: stable@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 @@ -28,6 +28,9 @@ #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 @@ -632,6 +635,7 @@ 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); } @@ -746,6 +750,7 @@ 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_PROCESS || @@ -798,6 +803,11 @@ 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(); }