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=-7.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 14B3DC282DF for ; Fri, 19 Apr 2019 18:59:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4BDA20645 for ; Fri, 19 Apr 2019 18:59:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=paul-moore-com.20150623.gappssmtp.com header.i=@paul-moore-com.20150623.gappssmtp.com header.b="wf+87+EI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728514AbfDSS7m (ORCPT ); Fri, 19 Apr 2019 14:59:42 -0400 Received: from mail-lj1-f195.google.com ([209.85.208.195]:34130 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728687AbfDSS7l (ORCPT ); Fri, 19 Apr 2019 14:59:41 -0400 Received: by mail-lj1-f195.google.com with SMTP id j89so5398221ljb.1 for ; Fri, 19 Apr 2019 11:59:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=z76qy/WYscT8yTKM3EVAchBs4dSJCLcS1D6tVIKxsTY=; b=wf+87+EIb4rIEjz9uA3YYlHwFC3NCiKJzU1g3OwuHSDIOFGIJAlWBstHMWhRp7nkIS zCy5nf6ld0NM/LDfTksi/wCqE0+6If9RD16LFxinXexEd7E7T8KXK+QjVPjz5F8wSVdM BXEZSpPUgmrKZeL0N3GbAqToD6N+V+zdTxthwVitP1WmLdHBzCzOu3pQUdeLXJqZ94uw ni4k51U+rpsJlGbmX6yHGaW6WAyp6MIN4FaQpw3hbEv9Aee9i9+BFBl/g/YX6iL6XbtO W5y9uFJWkWqpIGsdxPu2z1BJxM7Cere3gvBR46oLWGfcxcFXfoRt9lb6Msos5GHuEBze ZiDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=z76qy/WYscT8yTKM3EVAchBs4dSJCLcS1D6tVIKxsTY=; b=ihADVRFbzGgY19nino+NKGxFI1EJrhVPyPYOv4JJtGXNfzvIpTLl9mfX+vjtciQIzY 9xJg1JVYBEuB6a/wcGxiuBHBT+kLojCXnZkeUSX5jQEecrraXdYMlSImmaCjz0We2TNW CEyOAWDSzg7OM61GPqez4MrA5zJ7luYXX7yYe68GRV76EFWHxmOmI9ak5J6RIWTrZlVD 3oVvEvolipGgAuHXwLS/vAWSTHtib4YKrrQQHzljzPuWU2bWz00Rwe64oIHeKJPryS5c XpS3ILlzZsWBX65PN6BV/XdlakiBkpjG+ZAe1T2c9UenfNeNKYTYVXdj+Gn+YcTPWhPA 1KFA== X-Gm-Message-State: APjAAAU9+MdHRu81ok5RWKelpjoSY8zZwF36cmHkCEgiSYs/E3jSAjx8 ilHUNeSl0nBIo8rLahEsfZfVXqAx1YPsdxALCycf X-Google-Smtp-Source: APXvYqxD7fUYbYeicEBXyFM/4ELy//HHhu/G6PToGa+1DO64dMOqfSBCIafdH7SlNyjg0wLa2bPphC8ua/9dXY5ljrA= X-Received: by 2002:a2e:b01a:: with SMTP id y26mr3090917ljk.38.1555700379256; Fri, 19 Apr 2019 11:59:39 -0700 (PDT) MIME-Version: 1.0 References: <155570011247.27135.12509150054846153288.stgit@chester> In-Reply-To: <155570011247.27135.12509150054846153288.stgit@chester> From: Paul Moore Date: Fri, 19 Apr 2019 14:59:28 -0400 Message-ID: Subject: Re: [PATCH] proc: prevent changes to overridden credentials To: linux-security-module@vger.kernel.org Cc: selinux@vger.kernel.org, cj.chengjian@huawei.com, john.johansen@canonical.com, casey@schaufler-ca.com Content-Type: text/plain; charset="UTF-8" Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Fri, Apr 19, 2019 at 2:55 PM Paul Moore wrote: > Prevent userspace from changing the the /proc/PID/attr values if the > task's credentials are currently overriden. This not only makes sense > conceptually, it also prevents some really bizarre error cases caused > when trying to commit credentials to a task with overridden > credentials. > > Cc: > Reported-by: "chengjian (D)" > Signed-off-by: Paul Moore > --- > fs/proc/base.c | 5 +++++ > 1 file changed, 5 insertions(+) I sent this to the LSM list as I figure it should probably go via James' linux-security tree since it is cross-LSM and doesn't really contain any LSM specific code. That said, if you don't want this James let me know and I'll send it via the SELinux tree assuming I can get ACKs from John and Casey (this should only affect SELinux, AppArmor, and Smack). > diff --git a/fs/proc/base.c b/fs/proc/base.c > index ddef482f1334..87ba007b86db 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -2539,6 +2539,11 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, > rcu_read_unlock(); > return -EACCES; > } > + /* Prevent changes to overridden credentials. */ > + if (current_cred() != current_real_cred()) { > + rcu_read_unlock(); > + return -EBUSY; > + } > rcu_read_unlock(); > > if (count > PAGE_SIZE) > -- paul moore www.paul-moore.com