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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 3722CCA9EAF for ; Thu, 24 Oct 2019 11:39:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 01BF020679 for ; Thu, 24 Oct 2019 11:39:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VQDHu1Y9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01BF020679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40106 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iNbSK-0004L0-2O for qemu-devel@archiver.kernel.org; Thu, 24 Oct 2019 07:39:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39211) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iNbHF-0001Ue-Qr for qemu-devel@nongnu.org; Thu, 24 Oct 2019 07:27:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iNbHE-0008GM-Gz for qemu-devel@nongnu.org; Thu, 24 Oct 2019 07:27:37 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:58029 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iNbHE-0008FM-Cn for qemu-devel@nongnu.org; Thu, 24 Oct 2019 07:27:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571916455; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4FPgYQFbJ3wa5Enj07AEd7Fjkhsti21C0RndqxjWCWY=; b=VQDHu1Y969YbchyvyxlB7wz7ksDIH1spQ1hPTT5s3EbRIhOX0c+g+GjrOHizYqjcPupuNI ybKNQiDQNQdGuoZf5zL10HuryfQ8ak6BDadakIdGhjezD2vcUK9IW/1/n0mxOUVDVHwf2U 3vEWXUJtJJCdLAX2mnXa1n5j2YObV/0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-178-Yg2AnGDPMAGt8oGVVt1gXA-1; Thu, 24 Oct 2019 07:27:32 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6E164100550E; Thu, 24 Oct 2019 11:27:30 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-117-248.ams2.redhat.com [10.36.117.248]) by smtp.corp.redhat.com (Postfix) with ESMTP id E86224524; Thu, 24 Oct 2019 11:27:27 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, renzhen@linux.alibaba.com, eguan@linux.alibaba.com, ganesh.mahalingam@intel.com, m.mizuma@jp.fujitsu.com, mszeredi@redhat.com, misono.tomohiro@jp.fujitsu.com, tao.peng@linux.alibaba.com, piaojun@huawei.com, stefanha@redhat.com, vgoyal@redhat.com, mst@redhat.com, berrange@redhat.com Subject: [PATCH 01/25] virtiofsd: passthrough_ll: create new files in caller's context Date: Thu, 24 Oct 2019 12:26:54 +0100 Message-Id: <20191024112718.34657-2-dgilbert@redhat.com> In-Reply-To: <20191024112718.34657-1-dgilbert@redhat.com> References: <20191024112718.34657-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: Yg2AnGDPMAGt8oGVVt1gXA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Vivek Goyal We need to create files in callers context. Otherwise afer creating file, caller himself might not be able to do file operations on that file. Changed effective uid/gid to caller's uid/gid, create file and then switch backto uid/gid 0. Use syscall(setresuid, ...) otherwise glibc does some magic to change EUID in all threads, which is not what we want. Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi --- contrib/virtiofsd/passthrough_ll.c | 75 ++++++++++++++++++++++++++++-- 1 file changed, 71 insertions(+), 4 deletions(-) diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthr= ough_ll.c index 2a1a880224..2de35d4d3d 100644 --- a/contrib/virtiofsd/passthrough_ll.c +++ b/contrib/virtiofsd/passthrough_ll.c @@ -49,6 +49,7 @@ #include #include #include +#include #include =20 #include "passthrough_helpers.h" @@ -78,6 +79,11 @@ struct lo_inode { =09uint64_t refcount; /* protected by lo->mutex */ }; =20 +struct lo_cred { +=09uid_t euid; +=09gid_t egid; +}; + enum { =09CACHE_NEVER, =09CACHE_NORMAL, @@ -376,6 +382,51 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t paren= t, const char *name) =09=09fuse_reply_entry(req, &e); } =20 +/* + * Change to uid/gid of caller so that file is created with + * ownership of caller. + * TODO: What about selinux context? + */ +static int lo_change_cred(fuse_req_t req, struct lo_cred *old) +{ +=09int res; + +=09old->euid =3D geteuid(); +=09old->egid =3D getegid(); + +=09res =3D syscall(SYS_setresgid, -1,fuse_req_ctx(req)->gid, -1); +=09if (res =3D=3D -1) +=09=09return errno; + +=09res =3D syscall(SYS_setresuid, -1, fuse_req_ctx(req)->uid, -1); +=09if (res =3D=3D -1) { +=09=09int errno_save =3D errno; + +=09=09syscall(SYS_setresgid, -1, old->egid, -1); +=09=09return errno_save; +=09} + +=09return 0; +} + +/* Regain Privileges */ +static void lo_restore_cred(struct lo_cred *old) +{ +=09int res; + +=09res =3D syscall(SYS_setresuid, -1, old->euid, -1); +=09if (res =3D=3D -1) { +=09=09fuse_log(FUSE_LOG_ERR, "seteuid(%u): %m\n", old->euid); +=09=09exit(1); +=09} + +=09res =3D syscall(SYS_setresgid, -1, old->egid, -1); +=09if (res =3D=3D -1) { +=09=09fuse_log(FUSE_LOG_ERR, "setegid(%u): %m\n", old->egid); +=09=09exit(1); +=09} +} + static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent, =09=09=09 const char *name, mode_t mode, dev_t rdev, =09=09=09 const char *link) @@ -384,12 +435,20 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino= _t parent, =09int saverr; =09struct lo_inode *dir =3D lo_inode(req, parent); =09struct fuse_entry_param e; +=09struct lo_cred old =3D {}; =20 =09saverr =3D ENOMEM; =20 +=09saverr =3D lo_change_cred(req, &old); +=09if (saverr) +=09=09goto out; + =09res =3D mknod_wrapper(dir->fd, name, link, mode, rdev); =20 =09saverr =3D errno; + +=09lo_restore_cred(&old); + =09if (res =3D=3D -1) =09=09goto out; =20 @@ -768,23 +827,31 @@ static void lo_create(fuse_req_t req, fuse_ino_t pare= nt, const char *name, =09struct lo_data *lo =3D lo_data(req); =09struct fuse_entry_param e; =09int err; +=09struct lo_cred old =3D {}; =20 =09if (lo_debug(req)) =09=09fuse_log(FUSE_LOG_DEBUG, "lo_create(parent=3D%" PRIu64 ", name=3D%s)= \n", =09=09=09parent, name); =20 +=09err =3D lo_change_cred(req, &old); +=09if (err) +=09=09goto out; + =09fd =3D openat(lo_fd(req, parent), name, =09=09 (fi->flags | O_CREAT) & ~O_NOFOLLOW, mode); -=09if (fd =3D=3D -1) -=09=09return (void) fuse_reply_err(req, errno); +=09err =3D fd =3D=3D -1 ? errno : 0; +=09lo_restore_cred(&old); =20 -=09fi->fh =3D fd; +=09if (!err) { +=09=09fi->fh =3D fd; +=09=09err =3D lo_do_lookup(req, parent, name, &e); +=09} =09if (lo->cache =3D=3D CACHE_NEVER) =09=09fi->direct_io =3D 1; =09else if (lo->cache =3D=3D CACHE_ALWAYS) =09=09fi->keep_cache =3D 1; =20 -=09err =3D lo_do_lookup(req, parent, name, &e); +out: =09if (err) =09=09fuse_reply_err(req, err); =09else --=20 2.23.0