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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 61891C43381 for ; Mon, 11 Mar 2019 09:58:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1B5D5206BA for ; Mon, 11 Mar 2019 09:58:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B5D5206BA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A9DB98E0012; Mon, 11 Mar 2019 05:58:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A4F1A8E0002; Mon, 11 Mar 2019 05:58:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93BCE8E0012; Mon, 11 Mar 2019 05:58:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-qt1-f199.google.com (mail-qt1-f199.google.com [209.85.160.199]) by kanga.kvack.org (Postfix) with ESMTP id 6D8158E0002 for ; Mon, 11 Mar 2019 05:58:54 -0400 (EDT) Received: by mail-qt1-f199.google.com with SMTP id 43so4716811qtz.8 for ; Mon, 11 Mar 2019 02:58:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=PGlZNpLPnrRz03ht6RYxyNkJoNZ/4fN59S595sf35EM=; b=HBc3DSZrHzjK5fS2vIjKA/9NqXMnEAzbloPmrvNwjXAHiFDrJjuSfBW780STSe1qTG 5T5paDShzgX3+booQkPR/Chx8ELgJrKZIgATw0ebo4WnMElXduwWKaxz9voJ4sBL0qiA GE/sd+wvQ4uXfI78waWCvuLNO4lBHaNwJ2JyxEr101cRcArlUUJhRNfGdguaX8yyT9wh vtUj9sILKK+XtunHHKUrBOEFVAvh9h0lgCACxDv5+PfGY2RMH3Ebjk173W+J9Vi7jVSv N3eR/fz1tlniUKjDZmZZ0d6kuYToJda3D7hYmRyQe144EaAfxSUvt+UC2p6pHgHlWaSG GfeQ== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Gm-Message-State: APjAAAXm7IQAsFc6Moe7ezPnrMKL8QiqfiKF2o1bwwXKXfvb+jb2RiDy vz6f2BbNWzZ484EW/qaXY6QDnBP/HeEPl/zhtIr10zCOZBQUpgNeADg4cxSq70jh3ZQtaiKpAJ/ X2eiwgySDht+iOwBp9q+hw6S4LT4c4MbDyPQCJYrmQBDPZCvnbQDJFDoOfjJO73ZaiA== X-Received: by 2002:a0c:fa92:: with SMTP id o18mr5953290qvn.81.1552298334229; Mon, 11 Mar 2019 02:58:54 -0700 (PDT) X-Google-Smtp-Source: APXvYqxukSI1KopqEwQ9LcMwaxyN45h5aq083kaOxDuvUCXkHAda0MhSsk4IxHwaIQSsZM2OXK2P X-Received: by 2002:a0c:fa92:: with SMTP id o18mr5953266qvn.81.1552298333538; Mon, 11 Mar 2019 02:58:53 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1552298333; cv=none; d=google.com; s=arc-20160816; b=PoJqL5zqgrMBQq1xkdaeWpxNbFtK//lKHXs3JoNY9wibdbbRK4Mxqy4aDH9QteeTgt sR0AEV5j9TsrzUS1k0d/8Wi+2fgXsVe9R+at0QcR1EWFp9IBHp7I7R1DhVZuPjaEuNWS z7DzbhVtA0aceiiV5g7BCW9nhEFmZ0rXDLQ5UKSkgq0mCDVQ63Vf8AddFAw8mobvwLuv YamRpqCf6MJ/bojryv1t8pnTG++rCDnmO0PlIHQFSvekPOvIopaAzvr65zXEjyG3ePpt Q7RzMwRhV9++QHXFL81jBqM+8+ZIli5nZvswuv20kt6spWT+vhDW5k8Km0HH+nmd2JLW H1+Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=PGlZNpLPnrRz03ht6RYxyNkJoNZ/4fN59S595sf35EM=; b=GXHQ3OkJHhYibBqmSutQYfBzCmbOHypUbCCjZjvkNzsKUbJSIrDnnC1p2qpzF48Ygi KTHJefcDKrfOCipJF8Crg2ILcE3dkG/ICF+28+52B6DwmoVE4du6uuuCzHFaeCBcLBCN 1kw6KoQoDmqVVZhnLFmVQo4ydXjnN7N9sVB+ZsAw/9Rg9JDN9mIGg5tRArMAY73qyeZA hReJaUN+yn1vnbcPeguUwvyhc4n4LTk+1TmkrikMQKHJ2cgV6guu2YVTBvhKYiIsUa8R BAFdBCjXbYnG6qPp2vtbxr3otl+5ZVp0/dtN58SxMav2qKDvbc9gPuzZ7BA+JFCF9xhO Ecsg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id 24si3068796qtm.284.2019.03.11.02.58.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Mar 2019 02:58:53 -0700 (PDT) Received-SPF: pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D87BA3086265; Mon, 11 Mar 2019 09:58:51 +0000 (UTC) Received: from xz-x1 (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8C4DB5DA38; Mon, 11 Mar 2019 09:58:42 +0000 (UTC) Date: Mon, 11 Mar 2019 17:58:40 +0800 From: Peter Xu To: linux-kernel@vger.kernel.org Cc: Paolo Bonzini , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , kvm@vger.kernel.org, Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , linux-mm@kvack.org, Marty McFadden , Maya Gokhale , Mike Kravetz , Andrea Arcangeli , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , linux-fsdevel@vger.kernel.org, "Dr . David Alan Gilbert" , Andrew Morton Subject: Re: [PATCH 3/3] userfaultfd: apply unprivileged_userfaultfd check Message-ID: <20190311095840.GA14108@xz-x1> References: <20190311093701.15734-1-peterx@redhat.com> <20190311093701.15734-4-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190311093701.15734-4-peterx@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Mon, 11 Mar 2019 09:58:52 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 11, 2019 at 05:37:01PM +0800, Peter Xu wrote: > Apply the unprivileged_userfaultfd check when doing userfaultfd > syscall. We didn't check it in other paths of userfaultfd (e.g., the > ioctl() path) because we don't want to drag down the fast path of > userfaultfd, as suggested by Andrea. > > Suggested-by: Andrea Arcangeli > Suggested-by: Mike Rapoport > Signed-off-by: Peter Xu > --- > fs/userfaultfd.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index c2188464555a..effdcfc88629 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -951,6 +951,28 @@ void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf) > } > } > > +/* Whether current process allows to use userfaultfd syscalls */ > +static bool userfaultfd_allowed(void) > +{ > + bool allowed = false; > + > + switch (unprivileged_userfaultfd) { > + case UFFD_UNPRIV_ENABLED: > + allowed = true; > + break; > + case UFFD_UNPRIV_KVM: > + allowed = !!test_bit(MMF_USERFAULTFD_ALLOW, > + ¤t->mm->flags); > + /* Fall through */ Sorry I should squash this in otherwise compilation of !CONFIG_KVM will break: diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index effdcfc88629..1b3fa5935643 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -960,10 +960,12 @@ static bool userfaultfd_allowed(void) case UFFD_UNPRIV_ENABLED: allowed = true; break; +#if IS_ENABLED(CONFIG_KVM) case UFFD_UNPRIV_KVM: allowed = !!test_bit(MMF_USERFAULTFD_ALLOW, ¤t->mm->flags); /* Fall through */ +#endif case UFFD_UNPRIV_DISABLED: allowed = allowed || ns_capable(current_user_ns(), CAP_SYS_PTRACE); Will wait for more comments before I repost. Sorry for the noise. Regards, -- Peter Xu