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=-4.1 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, UNWANTED_LANGUAGE_BODY 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 A0A80C2D0CE for ; Tue, 21 Jan 2020 12:56:42 +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 5B8AA2051A for ; Tue, 21 Jan 2020 12:56:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QsrLFaw9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B8AA2051A 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]:53418 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1itt5F-0004NV-5J for qemu-devel@archiver.kernel.org; Tue, 21 Jan 2020 07:56:41 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:51822) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1itse5-0000DM-0B for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:28:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1itse1-0003ES-6w for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:28:36 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:60948 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 1itse0-0003E1-VF for qemu-devel@nongnu.org; Tue, 21 Jan 2020 07:28:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579609712; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KXUmF+JaaLkjBNCQITvqnO/hMDhsU03dR7T+jZPJMkc=; b=QsrLFaw9GgtbOXaYCODF4bQBQQsAHvji/U9KNtZBn/0OFQFMcv9AxTW5XemZjkmWqO3j9U vNLssRLoQCsEKrnnnKgNS1zs8+UU2Ko1ly3gpgBsnxXWKkoNip3zB1GOzGIUVTz/tj0xXl t85bh9Wa2StD0XXlu42EyFraIRY+QEk= 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-420-dUl41kDsPWaqnPxZAdlefQ-1; Tue, 21 Jan 2020 07:28:30 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A6AA11922960; Tue, 21 Jan 2020 12:28:29 +0000 (UTC) Received: from dgilbert-t580.localhost (unknown [10.36.118.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7F1D260BE0; Tue, 21 Jan 2020 12:28:25 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com, berrange@redhat.com, slp@redhat.com, philmd@redhat.com Subject: [PATCH v2 047/109] virtiofsd: use /proc/self/fd/ O_PATH file descriptor Date: Tue, 21 Jan 2020 12:23:31 +0000 Message-Id: <20200121122433.50803-48-dgilbert@redhat.com> In-Reply-To: <20200121122433.50803-1-dgilbert@redhat.com> References: <20200121122433.50803-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: dUl41kDsPWaqnPxZAdlefQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 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: , Cc: m.mizuma@jp.fujitsu.com, misono.tomohiro@jp.fujitsu.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Stefan Hajnoczi Sandboxing will remove /proc from the mount namespace so we can no longer build string paths into "/proc/self/fd/...". Keep an O_PATH file descriptor so we can still re-open fds via /proc/self/fd. Signed-off-by: Stefan Hajnoczi Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- tools/virtiofsd/passthrough_ll.c | 130 ++++++++++++++++++++++++------- 1 file changed, 103 insertions(+), 27 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index 7a16e6b4d6..322205ba3a 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -109,6 +109,9 @@ struct lo_data { struct lo_map ino_map; /* protected by lo->mutex */ struct lo_map dirp_map; /* protected by lo->mutex */ struct lo_map fd_map; /* protected by lo->mutex */ + + /* An O_PATH file descriptor to /proc/self/fd/ */ + int proc_self_fd; }; =20 static const struct fuse_opt lo_opts[] =3D { @@ -378,9 +381,9 @@ static int lo_parent_and_name(struct lo_data *lo, struc= t lo_inode *inode, int res; =20 retry: - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(procname, "%i", inode->fd); =20 - res =3D readlink(procname, path, PATH_MAX); + res =3D readlinkat(lo->proc_self_fd, procname, path, PATH_MAX); if (res < 0) { fuse_log(FUSE_LOG_WARNING, "%s: readlink failed: %m\n", __func__); goto fail_noretry; @@ -476,9 +479,9 @@ static int utimensat_empty(struct lo_data *lo, struct l= o_inode *inode, } return res; } - sprintf(path, "/proc/self/fd/%i", inode->fd); + sprintf(path, "%i", inode->fd); =20 - return utimensat(AT_FDCWD, path, tv, 0); + return utimensat(lo->proc_self_fd, path, tv, 0); =20 fallback: res =3D lo_parent_and_name(lo, inode, path, &parent); @@ -534,8 +537,8 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, = struct stat *attr, if (fi) { res =3D fchmod(fd, attr->st_mode); } else { - sprintf(procname, "/proc/self/fd/%i", ifd); - res =3D chmod(procname, attr->st_mode); + sprintf(procname, "%i", ifd); + res =3D fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0)= ; } if (res =3D=3D -1) { goto out_err; @@ -551,11 +554,23 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino= , struct stat *attr, } } if (valid & FUSE_SET_ATTR_SIZE) { + int truncfd; + if (fi) { - res =3D ftruncate(fd, attr->st_size); + truncfd =3D fd; } else { - sprintf(procname, "/proc/self/fd/%i", ifd); - res =3D truncate(procname, attr->st_size); + sprintf(procname, "%i", ifd); + truncfd =3D openat(lo->proc_self_fd, procname, O_RDWR); + if (truncfd < 0) { + goto out_err; + } + } + + res =3D ftruncate(truncfd, attr->st_size); + if (!fi) { + saverr =3D errno; + close(truncfd); + errno =3D saverr; } if (res =3D=3D -1) { goto out_err; @@ -873,9 +888,9 @@ static int linkat_empty_nofollow(struct lo_data *lo, st= ruct lo_inode *inode, return res; } =20 - sprintf(path, "/proc/self/fd/%i", inode->fd); + sprintf(path, "%i", inode->fd); =20 - return linkat(AT_FDCWD, path, dfd, name, AT_SYMLINK_FOLLOW); + return linkat(lo->proc_self_fd, path, dfd, name, AT_SYMLINK_FOLLOW); =20 fallback: res =3D lo_parent_and_name(lo, inode, path, &parent); @@ -1403,8 +1418,8 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, s= truct fuse_file_info *fi) fi->flags &=3D ~O_APPEND; } =20 - sprintf(buf, "/proc/self/fd/%i", lo_fd(req, ino)); - fd =3D open(buf, fi->flags & ~O_NOFOLLOW); + sprintf(buf, "%i", lo_fd(req, ino)); + fd =3D openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW); if (fd =3D=3D -1) { return (void)fuse_reply_err(req, errno); } @@ -1457,7 +1472,6 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, = int datasync, struct fuse_file_info *fi) { int res; - (void)ino; int fd; char *buf; =20 @@ -1465,12 +1479,14 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino= , int datasync, (void *)fi); =20 if (!fi) { - res =3D asprintf(&buf, "/proc/self/fd/%i", lo_fd(req, ino)); + struct lo_data *lo =3D lo_data(req); + + res =3D asprintf(&buf, "%i", lo_fd(req, ino)); if (res =3D=3D -1) { return (void)fuse_reply_err(req, errno); } =20 - fd =3D open(buf, O_RDWR); + fd =3D openat(lo->proc_self_fd, buf, O_RDWR); free(buf); if (fd =3D=3D -1) { return (void)fuse_reply_err(req, errno); @@ -1586,11 +1602,13 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino= , struct fuse_file_info *fi, static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name, size_t size) { + struct lo_data *lo =3D lo_data(req); char *value =3D NULL; char procname[64]; struct lo_inode *inode; ssize_t ret; int saverr; + int fd =3D -1; =20 inode =3D lo_inode(req, ino); if (!inode) { @@ -1615,7 +1633,11 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t i= no, const char *name, goto out; } =20 - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(procname, "%i", inode->fd); + fd =3D openat(lo->proc_self_fd, procname, O_RDONLY); + if (fd < 0) { + goto out_err; + } =20 if (size) { value =3D malloc(size); @@ -1623,7 +1645,7 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t in= o, const char *name, goto out_err; } =20 - ret =3D getxattr(procname, name, value, size); + ret =3D fgetxattr(fd, name, value, size); if (ret =3D=3D -1) { goto out_err; } @@ -1634,7 +1656,7 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t in= o, const char *name, =20 fuse_reply_buf(req, value, ret); } else { - ret =3D getxattr(procname, name, NULL, 0); + ret =3D fgetxattr(fd, name, NULL, 0); if (ret =3D=3D -1) { goto out_err; } @@ -1643,6 +1665,10 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t i= no, const char *name, } out_free: free(value); + + if (fd >=3D 0) { + close(fd); + } return; =20 out_err: @@ -1654,11 +1680,13 @@ out: =20 static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) { + struct lo_data *lo =3D lo_data(req); char *value =3D NULL; char procname[64]; struct lo_inode *inode; ssize_t ret; int saverr; + int fd =3D -1; =20 inode =3D lo_inode(req, ino); if (!inode) { @@ -1682,7 +1710,11 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t = ino, size_t size) goto out; } =20 - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(procname, "%i", inode->fd); + fd =3D openat(lo->proc_self_fd, procname, O_RDONLY); + if (fd < 0) { + goto out_err; + } =20 if (size) { value =3D malloc(size); @@ -1690,7 +1722,7 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t i= no, size_t size) goto out_err; } =20 - ret =3D listxattr(procname, value, size); + ret =3D flistxattr(fd, value, size); if (ret =3D=3D -1) { goto out_err; } @@ -1701,7 +1733,7 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t i= no, size_t size) =20 fuse_reply_buf(req, value, ret); } else { - ret =3D listxattr(procname, NULL, 0); + ret =3D flistxattr(fd, NULL, 0); if (ret =3D=3D -1) { goto out_err; } @@ -1710,6 +1742,10 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t = ino, size_t size) } out_free: free(value); + + if (fd >=3D 0) { + close(fd); + } return; =20 out_err: @@ -1723,9 +1759,11 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t i= no, const char *name, const char *value, size_t size, int flags) { char procname[64]; + struct lo_data *lo =3D lo_data(req); struct lo_inode *inode; ssize_t ret; int saverr; + int fd =3D -1; =20 inode =3D lo_inode(req, ino); if (!inode) { @@ -1750,21 +1788,31 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t = ino, const char *name, goto out; } =20 - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(procname, "%i", inode->fd); + fd =3D openat(lo->proc_self_fd, procname, O_RDWR); + if (fd < 0) { + saverr =3D errno; + goto out; + } =20 - ret =3D setxattr(procname, name, value, size, flags); + ret =3D fsetxattr(fd, name, value, size, flags); saverr =3D ret =3D=3D -1 ? errno : 0; =20 out: + if (fd >=3D 0) { + close(fd); + } fuse_reply_err(req, saverr); } =20 static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *nam= e) { char procname[64]; + struct lo_data *lo =3D lo_data(req); struct lo_inode *inode; ssize_t ret; int saverr; + int fd =3D -1; =20 inode =3D lo_inode(req, ino); if (!inode) { @@ -1788,12 +1836,20 @@ static void lo_removexattr(fuse_req_t req, fuse_ino= _t ino, const char *name) goto out; } =20 - sprintf(procname, "/proc/self/fd/%i", inode->fd); + sprintf(procname, "%i", inode->fd); + fd =3D openat(lo->proc_self_fd, procname, O_RDWR); + if (fd < 0) { + saverr =3D errno; + goto out; + } =20 - ret =3D removexattr(procname, name); + ret =3D fremovexattr(fd, name); saverr =3D ret =3D=3D -1 ? errno : 0; =20 out: + if (fd >=3D 0) { + close(fd); + } fuse_reply_err(req, saverr); } =20 @@ -1886,12 +1942,25 @@ static void print_capabilities(void) printf("}\n"); } =20 +static void setup_proc_self_fd(struct lo_data *lo) +{ + lo->proc_self_fd =3D open("/proc/self/fd", O_PATH); + if (lo->proc_self_fd =3D=3D -1) { + fuse_log(FUSE_LOG_ERR, "open(/proc/self/fd, O_PATH): %m\n"); + exit(1); + } +} + int main(int argc, char *argv[]) { struct fuse_args args =3D FUSE_ARGS_INIT(argc, argv); struct fuse_session *se; struct fuse_cmdline_opts opts; - struct lo_data lo =3D { .debug =3D 0, .writeback =3D 0 }; + struct lo_data lo =3D { + .debug =3D 0, + .writeback =3D 0, + .proc_self_fd =3D -1, + }; struct lo_map_elem *root_elem; int ret =3D -1; =20 @@ -2002,6 +2071,9 @@ int main(int argc, char *argv[]) =20 fuse_daemonize(opts.foreground); =20 + /* Must be after daemonize to get the right /proc/self/fd */ + setup_proc_self_fd(&lo); + /* Block until ctrl+c or fusermount -u */ ret =3D virtio_loop(se); =20 @@ -2017,6 +2089,10 @@ err_out1: lo_map_destroy(&lo.dirp_map); lo_map_destroy(&lo.ino_map); =20 + if (lo.proc_self_fd >=3D 0) { + close(lo.proc_self_fd); + } + if (lo.root.fd >=3D 0) { close(lo.root.fd); } --=20 2.24.1