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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,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 6127FC2D0DB for ; Thu, 23 Jan 2020 13:24:58 +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 2946521835 for ; Thu, 23 Jan 2020 13:24:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IbSPg8iT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2946521835 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]:56992 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iucTg-00082l-Ot for qemu-devel@archiver.kernel.org; Thu, 23 Jan 2020 08:24:56 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40550) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iub96-0002RG-Bo for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iub94-0005BC-6z for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:35 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:34639 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 1iub94-0005At-3C for qemu-devel@nongnu.org; Thu, 23 Jan 2020 06:59:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579780773; 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=pRi6vYFNhs/j1llGXVOGVhSwK/ObAljmvQ/qv9tM0tY=; b=IbSPg8iTVwW3aXwRVNdbLvX8K0bBVa9C7yeE+uDSZjbwJwg9HpE/kBA56PWVW+bMW68wAQ Na2XB2Wzf+0Dv+jLPPz+RyVmETJuYENPr34I7E17K5PV22w6WVt4m2r1xGBf/EjI4O2Xes zlBlPTk2jAnuA1YYPQbp4LiZ092eeUA= 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-87-IwmoCM3COz69hQGWpyqMUg-1; Thu, 23 Jan 2020 06:59:32 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 594D610120A2 for ; Thu, 23 Jan 2020 11:59:28 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id A6EB31CB; Thu, 23 Jan 2020 11:59:27 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 034/111] virtiofsd: passthrough_ll: create new files in caller's context Date: Thu, 23 Jan 2020 11:57:24 +0000 Message-Id: <20200123115841.138849-35-dgilbert@redhat.com> In-Reply-To: <20200123115841.138849-1-dgilbert@redhat.com> References: <20200123115841.138849-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: IwmoCM3COz69hQGWpyqMUg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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] X-Received-From: 207.211.31.120 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 the caller's context. Otherwise after creating a file, the caller 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 back to 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 Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 96 ++++++++++++++++++++++++++++++-- 1 file changed, 91 insertions(+), 5 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index cd27c09f59..5e061797d4 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -50,6 +50,7 @@ #include #include #include +#include #include #include =20 @@ -83,6 +84,11 @@ struct lo_inode { uint64_t refcount; /* protected by lo->mutex */ }; =20 +struct lo_cred { + uid_t euid; + gid_t egid; +}; + enum { CACHE_NEVER, CACHE_NORMAL, @@ -383,6 +389,69 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t paren= t, const char *name) } } =20 +/* + * On some archs, setres*id is limited to 2^16 but they + * provide setres*id32 variants that allow 2^32. + * Others just let setres*id do 2^32 anyway. + */ +#ifdef SYS_setresgid32 +#define OURSYS_setresgid SYS_setresgid32 +#else +#define OURSYS_setresgid SYS_setresgid +#endif + +#ifdef SYS_setresuid32 +#define OURSYS_setresuid SYS_setresuid32 +#else +#define OURSYS_setresuid SYS_setresuid +#endif + +/* + * 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) +{ + int res; + + old->euid =3D geteuid(); + old->egid =3D getegid(); + + res =3D syscall(OURSYS_setresgid, -1, fuse_req_ctx(req)->gid, -1); + if (res =3D=3D -1) { + return errno; + } + + res =3D syscall(OURSYS_setresuid, -1, fuse_req_ctx(req)->uid, -1); + if (res =3D=3D -1) { + int errno_save =3D errno; + + syscall(OURSYS_setresgid, -1, old->egid, -1); + return errno_save; + } + + return 0; +} + +/* Regain Privileges */ +static void lo_restore_cred(struct lo_cred *old) +{ + int res; + + res =3D syscall(OURSYS_setresuid, -1, old->euid, -1); + if (res =3D=3D -1) { + fuse_log(FUSE_LOG_ERR, "seteuid(%u): %m\n", old->euid); + exit(1); + } + + res =3D syscall(OURSYS_setresgid, -1, old->egid, -1); + if (res =3D=3D -1) { + fuse_log(FUSE_LOG_ERR, "setegid(%u): %m\n", old->egid); + exit(1); + } +} + static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent, const char *name, mode_t mode, dev_t rdev, const char *link) @@ -391,12 +460,21 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino= _t parent, int saverr; struct lo_inode *dir =3D lo_inode(req, parent); struct fuse_entry_param e; + struct lo_cred old =3D {}; =20 saverr =3D ENOMEM; =20 + saverr =3D lo_change_cred(req, &old); + if (saverr) { + goto out; + } + res =3D mknod_wrapper(dir->fd, name, link, mode, rdev); =20 saverr =3D errno; + + lo_restore_cred(&old); + if (res =3D=3D -1) { goto out; } @@ -794,26 +872,34 @@ static void lo_create(fuse_req_t req, fuse_ino_t pare= nt, const char *name, struct lo_data *lo =3D lo_data(req); struct fuse_entry_param e; int err; + struct lo_cred old =3D {}; =20 if (lo_debug(req)) { fuse_log(FUSE_LOG_DEBUG, "lo_create(parent=3D%" PRIu64 ", name=3D%= s)\n", parent, name); } =20 + err =3D lo_change_cred(req, &old); + if (err) { + goto out; + } + fd =3D openat(lo_fd(req, parent), name, (fi->flags | O_CREAT) & ~O_NOF= OLLOW, mode); - if (fd =3D=3D -1) { - return (void)fuse_reply_err(req, errno); - } + err =3D fd =3D=3D -1 ? errno : 0; + lo_restore_cred(&old); =20 - fi->fh =3D fd; + if (!err) { + fi->fh =3D fd; + err =3D lo_do_lookup(req, parent, name, &e); + } if (lo->cache =3D=3D CACHE_NEVER) { fi->direct_io =3D 1; } else if (lo->cache =3D=3D CACHE_ALWAYS) { fi->keep_cache =3D 1; } =20 - err =3D lo_do_lookup(req, parent, name, &e); +out: if (err) { fuse_reply_err(req, err); } else { --=20 2.24.1