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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Xiaoli Feng <xifeng@redhat.com>,
        Ronnie Sahlberg <lsahlber@redhat.com>,
        "Paulo Alcantara (SUSE)" <pc@cjr.nz>,
        Steve French <stfrench@microsoft.com>
Subject: [PATCH 5.12 003/292] cifs: Do not use the original cruid when following DFS links for multiuser mounts
Date:   Mon, 19 Jul 2021 16:51:05 +0200
Message-Id: <20210719144942.629302443@linuxfoundation.org>
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From: Ronnie Sahlberg <lsahlber@redhat.com>

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(+)

--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -208,6 +208,10 @@ char *cifs_compose_mount_options(const c
 		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;