From nobody Thu Nov 6 18:51:53 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 1488237924668149.11424331708486; Mon, 27 Feb 2017 15:25:24 -0800 (PST) Received: from localhost ([::1]:57548 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUfT-0004Nq-CR for importer@patchew.org; Mon, 27 Feb 2017 18:25:23 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47015) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ciUHr-0000eE-1l for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:01:00 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ciUHn-00044f-Tv for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:00:59 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:45099) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ciUHn-00043D-KD for qemu-devel@nongnu.org; Mon, 27 Feb 2017 18:00:55 -0500 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1RMrb5W138299 for ; Mon, 27 Feb 2017 18:00:54 -0500 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 28vjd4pyny-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Feb 2017 18:00:54 -0500 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 27 Feb 2017 23:00:50 -0000 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id A4A6117D8042; Mon, 27 Feb 2017 23:04:02 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v1RN0nuM66781370; Mon, 27 Feb 2017 23:00:49 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 71E3E4203F; Mon, 27 Feb 2017 23:00:44 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6145842049; Mon, 27 Feb 2017 23:00:44 +0000 (GMT) Received: from smtp.lab.toulouse-stg.fr.ibm.com (unknown [9.101.4.1]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 27 Feb 2017 23:00:44 +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 B6EC2220225; Tue, 28 Feb 2017 00:00:48 +0100 (CET) From: Greg Kurz To: qemu-devel@nongnu.org Date: Tue, 28 Feb 2017 00:00:11 +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: 17022723-0028-0000-0000-000002B2F608 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17022723-0029-0000-0000-000022860014 Message-Id: <1488236421-30983-22-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: 148.163.156.1 Subject: [Qemu-devel] [PULL 21/31] 9pfs: local: renameat: 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_renameat() callback is currently a wrapper around local_rename() which is vulnerable to symlink attacks. This patch rewrites local_renameat() to have its own implementation, based on local_opendir_nofollow() and renameat(). This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz Reviewed-by: Stefan Hajnoczi --- hw/9pfs/9p-local.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++----= ---- 1 file changed, 64 insertions(+), 10 deletions(-) diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c index ee3c1bd0a2be..cf9e03d8e64f 100644 --- a/hw/9pfs/9p-local.c +++ b/hw/9pfs/9p-local.c @@ -67,6 +67,14 @@ int local_opendir_nofollow(FsContext *fs_ctx, const char= *path) return local_open_nofollow(fs_ctx, path, O_DIRECTORY | O_RDONLY, 0); } =20 +static void renameat_preserve_errno(int odirfd, const char *opath, int ndi= rfd, + const char *npath) +{ + int serrno =3D errno; + renameat(odirfd, opath, ndirfd, npath); + errno =3D serrno; +} + #define VIRTFS_META_DIR ".virtfs_metadata" =20 static char *local_mapped_attr_path(FsContext *ctx, const char *path) @@ -146,8 +154,7 @@ static void local_mapped_file_attr(int dirfd, const cha= r *name, char buf[ATTR_MAX]; int map_dirfd; =20 - map_dirfd =3D openat(dirfd, VIRTFS_META_DIR, - O_RDONLY | O_DIRECTORY | O_NOFOLLOW); + map_dirfd =3D openat_dir(dirfd, VIRTFS_META_DIR); if (map_dirfd =3D=3D -1) { return; } @@ -1186,17 +1193,64 @@ static int local_renameat(FsContext *ctx, V9fsPath = *olddir, const char *new_name) { int ret; - V9fsString old_full_name, new_full_name; + int odirfd, ndirfd; + + odirfd =3D local_opendir_nofollow(ctx, olddir->data); + if (odirfd =3D=3D -1) { + return -1; + } + + ndirfd =3D local_opendir_nofollow(ctx, newdir->data); + if (ndirfd =3D=3D -1) { + close_preserve_errno(odirfd); + return -1; + } + + ret =3D renameat(odirfd, old_name, ndirfd, new_name); + if (ret < 0) { + goto out; + } =20 - v9fs_string_init(&old_full_name); - v9fs_string_init(&new_full_name); + if (ctx->export_flags & V9FS_SM_MAPPED_FILE) { + int omap_dirfd, nmap_dirfd; =20 - v9fs_string_sprintf(&old_full_name, "%s/%s", olddir->data, old_name); - v9fs_string_sprintf(&new_full_name, "%s/%s", newdir->data, new_name); + ret =3D mkdirat(ndirfd, VIRTFS_META_DIR, 0700); + if (ret < 0 && errno !=3D EEXIST) { + goto err_undo_rename; + } =20 - ret =3D local_rename(ctx, old_full_name.data, new_full_name.data); - v9fs_string_free(&old_full_name); - v9fs_string_free(&new_full_name); + omap_dirfd =3D openat(odirfd, VIRTFS_META_DIR, + O_RDONLY | O_DIRECTORY | O_NOFOLLOW); + if (omap_dirfd =3D=3D -1) { + goto err; + } + + nmap_dirfd =3D openat(ndirfd, VIRTFS_META_DIR, + O_RDONLY | O_DIRECTORY | O_NOFOLLOW); + if (nmap_dirfd =3D=3D -1) { + close_preserve_errno(omap_dirfd); + goto err; + } + + /* rename the .virtfs_metadata files */ + ret =3D renameat(omap_dirfd, old_name, nmap_dirfd, new_name); + close_preserve_errno(nmap_dirfd); + close_preserve_errno(omap_dirfd); + if (ret < 0 && errno !=3D ENOENT) { + goto err_undo_rename; + } + + ret =3D 0; + } + goto out; + +err: + ret =3D -1; +err_undo_rename: + renameat_preserve_errno(ndirfd, new_name, odirfd, old_name); +out: + close_preserve_errno(ndirfd); + close_preserve_errno(odirfd); return ret; } =20 --=20 2.7.4