From d4e376c83736c49d2150b2d8cb13c5436083370f Mon Sep 17 00:00:00 2001
From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Tue, 13 Jul 2021 12:22:59 +1000
Subject: [PATCH] cifs: Do not use the original cruid when following DFS links
 for multiuser mounts

commit 50630b3f1ada0bf412d3f28e73bac310448d9d6f upstream.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213565

cruid should only be used for the initial mount and after this we should use the current
users credentials.
Ignore the original cruid mount argument when creating a new context for a multiuser mount
following a DFS link.

Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Cc: stable@vger.kernel.org # 5.11+
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/cifs/cifs_dfs_ref.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 4f2c68e4a53d9..8dec4edc8a9fe 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -208,6 +208,10 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 		else
 			noff = tkn_e - (sb_mountdata + off) + 1;
 
+		if (strncasecmp(sb_mountdata + off, "cruid=", 6) == 0) {
+			off += noff;
+			continue;
+		}
 		if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
 			off += noff;
 			continue;