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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, "Paulo Alcantara (SUSE)" <pc@cjr.nz>,
        Aurelien Aptel <aaptel@suse.com>,
        Steve French <stfrench@microsoft.com>
Subject: [PATCH 5.4 170/191] cifs: Fix lookup of root ses in DFS referral cache
Date:   Tue,  7 Jan 2020 21:54:50 +0100
Message-Id: <20200107205342.101065922@linuxfoundation.org>
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From: Paulo Alcantara (SUSE) <pc@cjr.nz>

commit df3df923b31d298c3d3653a0380202b9f2df9864 upstream.

We don't care about module aliasing validation in
cifs_compose_mount_options(..., is_smb3) when finding the root SMB
session of an DFS namespace in order to refresh DFS referral cache.

The following issue has been observed when mounting with '-t smb3' and
then specifying 'vers=2.0':

...
Nov 08 15:27:08 tw kernel: address conversion returned 0 for FS0.WIN.LOCAL
Nov 08 15:27:08 tw kernel: [kworke] ==> dns_query((null),FS0.WIN.LOCAL,13,(null))
Nov 08 15:27:08 tw kernel: [kworke] call request_key(,FS0.WIN.LOCAL,)
Nov 08 15:27:08 tw kernel: [kworke] ==> dns_resolver_cmp(FS0.WIN.LOCAL,FS0.WIN.LOCAL)
Nov 08 15:27:08 tw kernel: [kworke] <== dns_resolver_cmp() = 1
Nov 08 15:27:08 tw kernel: [kworke] <== dns_query() = 13
Nov 08 15:27:08 tw kernel: fs/cifs/dns_resolve.c: dns_resolve_server_name_to_ip: resolved: FS0.WIN.LOCAL to 192.168.30.26
===> Nov 08 15:27:08 tw kernel: CIFS VFS: vers=2.0 not permitted when mounting with smb3
Nov 08 15:27:08 tw kernel: fs/cifs/dfs_cache.c: CIFS VFS: leaving refresh_tcon (xid = 26) rc = -22
...

Fixes: 5072010ccf05 ("cifs: Fix DFS cache refresher for DFS links")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/dfs_cache.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1317,7 +1317,6 @@ static struct cifs_ses *find_root_ses(st
 	int rc;
 	struct dfs_info3_param ref = {0};
 	char *mdata = NULL, *devname = NULL;
-	bool is_smb3 = tcon->ses->server->vals->header_preamble_size == 0;
 	struct TCP_Server_Info *server;
 	struct cifs_ses *ses;
 	struct smb_vol vol;
@@ -1344,7 +1343,7 @@ static struct cifs_ses *find_root_ses(st
 		goto out;
 	}
 
-	rc = cifs_setup_volume_info(&vol, mdata, devname, is_smb3);
+	rc = cifs_setup_volume_info(&vol, mdata, devname, false);
 	kfree(devname);
 
 	if (rc) {