From patchwork Wed Dec 5 04:02:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Chinner X-Patchwork-Id: 10712951 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8603F13AF for ; Wed, 5 Dec 2018 04:16:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 728DF2883C for ; Wed, 5 Dec 2018 04:16:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 65C722895F; Wed, 5 Dec 2018 04:16:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EFD3928990 for ; Wed, 5 Dec 2018 04:16:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726001AbeLEEQY (ORCPT ); Tue, 4 Dec 2018 23:16:24 -0500 Received: from ipmail03.adl6.internode.on.net ([150.101.137.143]:30691 "EHLO ipmail03.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725979AbeLEEQY (ORCPT ); Tue, 4 Dec 2018 23:16:24 -0500 Received: from ppp59-167-129-252.static.internode.on.net (HELO dastard) ([59.167.129.252]) by ipmail03.adl6.internode.on.net with ESMTP; 05 Dec 2018 14:32:29 +1030 Received: from dave by dastard with local (Exim 4.80) (envelope-from ) id 1gUOOI-0006KF-Hl for linux-xfs@vger.kernel.org; Wed, 05 Dec 2018 15:02:26 +1100 Date: Wed, 5 Dec 2018 15:02:26 +1100 From: Dave Chinner To: linux-xfs@vger.kernel.org Subject: [PATCH 2/2 V2] xfs_io: allow open file permissions to be changed Message-ID: <20181205040226.GS6311@dastard> References: <20181202205343.7104-1-david@fromorbit.com> <20181202205343.7104-3-david@fromorbit.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181202205343.7104-3-david@fromorbit.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Dave Chinner I need to be able to open a file read-write, then change the permissions on the file to read-only to check that copy_file_range returns EPERM correctly in that case. This can't be done as root, because root ignores file permissions, but as a normal user we can't open a 0444 file for writing and so can't actually test writing to a read-only file without some method of "open read-write, change permissions to read-only, try to write to file through open read-write file". So, allow adding or removing write permissions on an open file. Signed-off-by: Dave Chinner Reviewed-by: Eric Sandeen --- Version 2: - include a man page update from the new function io/open.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ man/man8/xfs_io.8 | 9 +++++++++ 2 files changed, 63 insertions(+) diff --git a/io/open.c b/io/open.c index 21c0e054f8d2..2663c38e9681 100644 --- a/io/open.c +++ b/io/open.c @@ -44,6 +44,7 @@ static cmdinfo_t chproj_cmd; static cmdinfo_t lsproj_cmd; static cmdinfo_t extsize_cmd; static cmdinfo_t inode_cmd; +static cmdinfo_t chmod_cmd; static prid_t prid; static long extsize; @@ -809,6 +810,48 @@ inode_f( return 0; } +static void +chmod_help(void) +{ + printf(_( +"\n" +" Change the read/write permissions on the current file\n" +"\n" +" Options:\n" +" -r -- make the file read only (0444 permissions)\n" +" -w -- make the file read/write (0664 permissions)\n" +"\n")); +} + +static int +chmod_f( + int argc, + char **argv) +{ + mode_t mode = S_IRUSR | S_IRGRP | S_IROTH; + int c; + + while ((c = getopt(argc, argv, "rw")) != EOF) { + switch (c) { + case 'r': + break; + case 'w': + mode |= S_IWUSR | S_IWGRP; + break; + default: + return command_usage(&chmod_cmd); + } + } + + if (argc != optind) + return command_usage(&chmod_cmd); + + if (fchmod(file->fd, mode) < 0) { + exitcode = 1; + perror("fchmod"); + } + return 0; +} void open_init(void) { @@ -871,10 +914,21 @@ open_init(void) _("Query inode number usage in the filesystem"); inode_cmd.help = inode_help; + chmod_cmd.name = "chmod"; + chmod_cmd.cfunc = chmod_f; + chmod_cmd.args = _("-r | -w"); + chmod_cmd.argmin = 1; + chmod_cmd.argmax = 1; + chmod_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK | CMD_FLAG_ONESHOT; + chmod_cmd.oneline = + _("change the read/write permissios on the currently open file"); + chmod_cmd.help = chmod_help; + add_command(&open_cmd); add_command(&close_cmd); add_command(&chproj_cmd); add_command(&lsproj_cmd); add_command(&extsize_cmd); add_command(&inode_cmd); + add_command(&chmod_cmd); } diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8 index f1099c32de66..68e03b4558b9 100644 --- a/man/man8/xfs_io.8 +++ b/man/man8/xfs_io.8 @@ -1226,6 +1226,15 @@ characters long. .B crc32cselftest Test the internal crc32c implementation to make sure that it computes results correctly. +.TP +.B chmod \-r | \-w +Change the mode of the currently open file. The +.B \-r +option will set the file permissions to read-only (0444), whilst the +.B \-w +option will set the file permissions to read-write (0644). This allows xfs_io to +set up mismatches between the file permissions and the open file descriptor +read/write mode to exercise permission checks inside various syscalls. .SH SEE ALSO .BR mkfs.xfs (8), .BR xfsctl (3),