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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 88894C5DF62 for ; Tue, 5 Nov 2019 15:29:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 56922222D1 for ; Tue, 5 Nov 2019 15:29:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 56922222D1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8BE986B000A; Tue, 5 Nov 2019 10:29:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8700A6B000C; Tue, 5 Nov 2019 10:29:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 736036B000D; Tue, 5 Nov 2019 10:29:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 5B4D16B000A for ; Tue, 5 Nov 2019 10:29:53 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 1F5898249980 for ; Tue, 5 Nov 2019 15:29:53 +0000 (UTC) X-FDA: 76122609066.22.spoon06_734ee56075b5d X-HE-Tag: spoon06_734ee56075b5d X-Filterd-Recvd-Size: 5251 Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 Nov 2019 15:29:52 +0000 (UTC) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id xA5FRjN2048647 for ; Tue, 5 Nov 2019 10:29:51 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0b-001b2d01.pphosted.com with ESMTP id 2w3bbp1h2t-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 05 Nov 2019 10:29:50 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 5 Nov 2019 15:29:48 -0000 Received: from b06avi18626390.portsmouth.uk.ibm.com (9.149.26.192) by e06smtp05.uk.ibm.com (192.168.101.135) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 5 Nov 2019 15:29:44 -0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xA5FT82Z18809216 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 5 Nov 2019 15:29:08 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 822D352052; Tue, 5 Nov 2019 15:29:43 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.59]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTPS id 703345204E; Tue, 5 Nov 2019 15:29:41 +0000 (GMT) Received: by rapoport-lnx (sSMTP sendmail emulation); Tue, 05 Nov 2019 17:29:40 +0200 From: Mike Rapoport To: linux-kernel@vger.kernel.org Cc: Andrea Arcangeli , Andrew Morton , Andy Lutomirski , Daniel Colascione , Jann Horn , Linus Torvalds , Lokesh Gidra , Nick Kralevich , Nosh Minwalla , Pavel Emelyanov , Tim Murray , linux-api@vger.kernel.org, linux-mm@kvack.org, Mike Rapoport Subject: [PATCH 1/1] userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK Date: Tue, 5 Nov 2019 17:29:37 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1572967777-8812-1-git-send-email-rppt@linux.ibm.com> References: <1572967777-8812-1-git-send-email-rppt@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19110515-0020-0000-0000-00000382C8FB X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19110515-0021-0000-0000-000021D8F36B Message-Id: <1572967777-8812-2-git-send-email-rppt@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-11-05_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1911050127 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: Current implementation of UFFD_FEATURE_EVENT_FORK modifies the file descriptor table from the read() implementation of uffd, which may have security implications for unprivileged use of the userfaultfd. Limit availability of UFFD_FEATURE_EVENT_FORK only for callers that have CAP_SYS_PTRACE. Signed-off-by: Mike Rapoport --- fs/userfaultfd.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index f9fd18670e22..d99d166fd892 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1834,13 +1834,12 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) goto out; features = uffdio_api.features; - if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) { - memset(&uffdio_api, 0, sizeof(uffdio_api)); - if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) - goto out; - ret = -EINVAL; - goto out; - } + ret = -EINVAL; + if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) + goto err_out; + ret = -EPERM; + if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE)) + goto err_out; /* report all available features and ioctls to userland */ uffdio_api.features = UFFD_API_FEATURES; uffdio_api.ioctls = UFFD_API_IOCTLS; @@ -1853,6 +1852,11 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, ret = 0; out: return ret; +err_out: + memset(&uffdio_api, 0, sizeof(uffdio_api)); + if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) + ret = -EFAULT; + goto out; } static long userfaultfd_ioctl(struct file *file, unsigned cmd, -- 2.7.4