From nobody Mon Feb 9 00:42:50 2026 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 1490054788874846.5413677339834; Mon, 20 Mar 2017 17:06:28 -0700 (PDT) Received: from localhost ([::1]:35821 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cq7Jj-00080n-Ko for importer@patchew.org; Mon, 20 Mar 2017 20:06:27 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42095) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cq6RC-0002Dw-CH for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:10:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cq6R0-0005Mb-0L for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:10:06 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40305 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 1cq6Qz-0005LZ-Nd for qemu-devel@nongnu.org; Mon, 20 Mar 2017 19:09:53 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2KN8YoP028796 for ; Mon, 20 Mar 2017 19:09:53 -0400 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0b-001b2d01.pphosted.com with ESMTP id 29amb5t7kb-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 20 Mar 2017 19:09:53 -0400 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 20 Mar 2017 19:09:51 -0400 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v2KN9oSK45940750; Mon, 20 Mar 2017 23:09:50 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 20B44112051; Mon, 20 Mar 2017 19:09:49 -0400 (EDT) Received: from localhost (unknown [9.53.92.194]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP id 0518511204B; Mon, 20 Mar 2017 19:09:49 -0400 (EDT) From: Michael Roth To: qemu-devel@nongnu.org Date: Mon, 20 Mar 2017 18:07:32 -0500 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1490051325-3770-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1490051325-3770-1-git-send-email-mdroth@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17032023-0024-0000-0000-0000021F8DE8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006819; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000206; SDB=6.00836553; UDB=6.00411162; IPR=6.00614321; BA=6.00005224; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014732; XFM=3.00000013; UTC=2017-03-20 23:09:52 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17032023-0025-0000-0000-000042B6B74B Message-Id: <1490051325-3770-9-git-send-email-mdroth@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-03-20_16:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=3 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703200196 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PATCH 08/81] 9pfs: local: llistxattr: 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: Greg Kurz , qemu-stable@nongnu.org, 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" From: Greg Kurz The local_llistxattr() callback is vulnerable to symlink attacks because it calls llistxattr() which follows symbolic links in all path elements but the rightmost one. This patch introduces a helper to emulate the non-existing flistxattrat() function: it is implemented with /proc/self/fd which provides a trusted path that can be safely passed to llistxattr(). local_llistxattr() is converted to use this helper and opendir_nofollow(). This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz Reviewed-by: Stefan Hajnoczi (cherry picked from commit 5507904e362df252f6065cb27d1ff98372db6abc) Signed-off-by: Greg Kurz Signed-off-by: Michael Roth --- hw/9pfs/9p-xattr.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/hw/9pfs/9p-xattr.c b/hw/9pfs/9p-xattr.c index aa4391e..54193c6 100644 --- a/hw/9pfs/9p-xattr.c +++ b/hw/9pfs/9p-xattr.c @@ -60,6 +60,16 @@ ssize_t pt_listxattr(FsContext *ctx, const char *path, return name_size; } =20 +static ssize_t flistxattrat_nofollow(int dirfd, const char *filename, + char *list, size_t size) +{ + char *proc_path =3D g_strdup_printf("/proc/self/fd/%d/%s", dirfd, file= name); + int ret; + + ret =3D llistxattr(proc_path, list, size); + g_free(proc_path); + return ret; +} =20 /* * Get the list and pass to each layer to find out whether @@ -69,24 +79,37 @@ ssize_t v9fs_list_xattr(FsContext *ctx, const char *pat= h, void *value, size_t vsize) { ssize_t size =3D 0; - char *buffer; void *ovalue =3D value; XattrOperations *xops; char *orig_value, *orig_value_start; ssize_t xattr_len, parsed_len =3D 0, attr_len; + char *dirpath, *name; + int dirfd; =20 /* Get the actual len */ - buffer =3D rpath(ctx, path); - xattr_len =3D llistxattr(buffer, value, 0); + dirpath =3D g_path_get_dirname(path); + dirfd =3D local_opendir_nofollow(ctx, dirpath); + g_free(dirpath); + if (dirfd =3D=3D -1) { + return -1; + } + + name =3D g_path_get_basename(path); + xattr_len =3D flistxattrat_nofollow(dirfd, name, value, 0); if (xattr_len <=3D 0) { - g_free(buffer); + g_free(name); + close_preserve_errno(dirfd); return xattr_len; } =20 /* Now fetch the xattr and find the actual size */ orig_value =3D g_malloc(xattr_len); - xattr_len =3D llistxattr(buffer, orig_value, xattr_len); - g_free(buffer); + xattr_len =3D flistxattrat_nofollow(dirfd, name, orig_value, xattr_len= ); + g_free(name); + close_preserve_errno(dirfd); + if (xattr_len < 0) { + return -1; + } =20 /* store the orig pointer */ orig_value_start =3D orig_value; --=20 2.7.4