From: Malahal Naineni <malahal@us.ibm.com>
To: linux-nfs@vger.kernel.org
Subject: [PATCH] Check for beginning '/' in the mount path
Date: Thu,  2 Feb 2012 19:42:12 -0600
Message-Id: <1328233332-26020-1-git-send-email-malahal@us.ibm.com>
Sender: linux-nfs-owner@vger.kernel.org

NFSv4 gladly accepts and mounts "hostname:path" instead of
"hostname:/path". This causes mount entry mistmatch between /etc/mtab
and /proc/mounts files. The former will have "hostname:path" but the
latter will have "hostname:/path". This causes umount not work at all.

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
---
 utils/mount/stropts.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index d52e21a..559114d 100644
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -571,6 +571,7 @@ static int nfs_sys_mount(struct nfsmount_info *mi, struct mount_options *opts)
 {
 	char *options = NULL;
 	int result;
+	char *dirname;
 
 	if (mi->fake)
 		return 1;
@@ -580,6 +581,27 @@ static int nfs_sys_mount(struct nfsmount_info *mi, struct mount_options *opts)
 		return 0;
 	}
 
+	/*
+	 * Make sure that dirname in the spec starts with '/'. The mount
+	 * works fine in NFSv4 without the '/', but then /etc/mtab and
+	 * /proc/mounts disagree on the actual mount entry causing later
+	 * umount to fail! There is no reason to allow any dirname not
+	 * starting with '/', so fail it here.
+	 *
+	 * Note that for NFSv2 and NFSv3, the mount call itself fails if
+	 * dirname doesn't start with '/'. So this check is only useful
+	 * for NFSv4.
+	 */
+	dirname = strchr(mi->spec, ']');	/* IPv6 address check */
+	if (dirname)
+		dirname = strchr(dirname+1, ':');
+	else
+		dirname = strchr(mi->spec, ':');
+	if (!dirname || *(dirname+1) != '/') {
+		errno = EINVAL;
+		return 0;
+	}
+
 	result = mount(mi->spec, mi->node, mi->type,
 			mi->flags & ~(MS_USER|MS_USERS), options);
 	free(options);
-- 
1.7.8.3