From nobody Thu Nov 6 18:51:54 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1488237129320207.044675523897; Mon, 27 Feb 2017 15:12:09 -0800 (PST) Received: from localhost ([::1]:57481 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUSd-00013N-J8 for importer@patchew.org; Mon, 27 Feb 2017 18:12:07 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46899) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUHl-0000Ye-PD for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:00:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ciUHk-0003zr-Po for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:00:53 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47244 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ciUHk-0003yr-IV for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:00:52 -0500 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1RMrbx0010739 for ; Mon, 27 Feb 2017 18:00:51 -0500 Received: from e06smtp06.uk.ibm.com (e06smtp06.uk.ibm.com [195.75.94.102]) by mx0b-001b2d01.pphosted.com with ESMTP id 28vp2342ev-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Feb 2017 18:00:51 -0500 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 27 Feb 2017 23:00:47 -0000 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 8A3371B08067; Mon, 27 Feb 2017 23:03:48 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v1RN0kGD1442160; Mon, 27 Feb 2017 23:00:46 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7A0CC4C050; Mon, 27 Feb 2017 23:00:33 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 66EBA4C04A; Mon, 27 Feb 2017 23:00:33 +0000 (GMT) Received: from smtp.lab.toulouse-stg.fr.ibm.com (unknown [9.101.4.1]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 27 Feb 2017 23:00:33 +0000 (GMT) Received: from bahia.lan (icon-9-164-183-34.megacenter.de.ibm.com [9.164.183.34]) by smtp.lab.toulouse-stg.fr.ibm.com (Postfix) with ESMTP id 9353A220711; Tue, 28 Feb 2017 00:00:44 +0100 (CET) From: Greg Kurz To: qemu-devel@nongnu.org Date: Tue, 28 Feb 2017 00:00:06 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488236421-30983-1-git-send-email-groug@kaod.org> References: <1488236421-30983-1-git-send-email-groug@kaod.org> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17022723-0024-0000-0000-000002BDEB00 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17022723-0025-0000-0000-0000228D3E7C Message-Id: <1488236421-30983-17-git-send-email-groug@kaod.org> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-02-27_17:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=13 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702270213 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PULL 16/31] 9pfs: local: utimensat: don't follow symlinks X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , "Aneesh Kumar K.V" , Greg Kurz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The local_utimensat() callback is vulnerable to symlink attacks because it calls qemu_utimens()->utimensat(AT_SYMLINK_NOFOLLOW) which follows symbolic links in all path elements but the rightmost one or qemu_utimens()->utimes() which follows symbolic links for all path elements. This patch converts local_utimensat() to rely on opendir_nofollow() and utimensat(AT_SYMLINK_NOFOLLOW) directly instead of using qemu_utimens(). It is hence assumed that the OS supports utimensat(), i.e. has glibc 2.6 or higher and linux 2.6.22 or higher, which seems reasonable nowadays. This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz Reviewed-by: Stefan Hajnoczi --- hw/9pfs/9p-local.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c index 53a2fd50edbb..bab095353da7 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -959,13 +959,20 @@ static int local_chown(FsContext *fs_ctx, V9fsPath *f= s_path, FsCred *credp) static int local_utimensat(FsContext *s, V9fsPath *fs_path, const struct timespec *buf) { - char *buffer; - int ret; - char *path =3D fs_path->data; + char *dirpath =3D g_path_get_dirname(fs_path->data); + char *name =3D g_path_get_basename(fs_path->data); + int dirfd, ret =3D -1; =20 - buffer =3D rpath(s, path); - ret =3D qemu_utimens(buffer, buf); - g_free(buffer); + dirfd =3D local_opendir_nofollow(s, dirpath); + if (dirfd =3D=3D -1) { + goto out; + } + + ret =3D utimensat(dirfd, name, buf, AT_SYMLINK_NOFOLLOW); + close_preserve_errno(dirfd); +out: + g_free(dirpath); + g_free(name); return ret; } =20 --=20 2.7.4