From 5fde3c21cf33830eda7bfd006dc7f4bf07ec9fe6 Mon Sep 17 00:00:00 2001
From: Marios Makassikis <mmakassikis@freebox.fr>
Date: Wed, 11 Jan 2023 17:39:02 +0100
Subject: [PATCH] ksmbd: do not sign response to session request for guest
login
If ksmbd.mountd is configured to assign unknown users to the guest account
("map to guest = bad user" in the config), ksmbd signs the response.
This is wrong according to MS-SMB2 3.3.5.5.3:
12. If the SMB2_SESSION_FLAG_IS_GUEST bit is not set in the SessionFlags
field, and Session.IsAnonymous is FALSE, the server MUST sign the
final session setup response before sending it to the client, as
follows:
[...]
This fixes libsmb2 based applications failing to establish a session
("Wrong signature in received").
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/ksmbd/smb2pdu.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 38fbda52e06fe..d681f91947d92 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -8663,6 +8663,7 @@ int smb3_decrypt_req(struct ksmbd_work *work)
bool smb3_11_final_sess_setup_resp(struct ksmbd_work *work)
{
struct ksmbd_conn *conn = work->conn;
+ struct ksmbd_session *sess = work->sess;
struct smb2_hdr *rsp = smb2_get_msg(work->response_buf);
if (conn->dialect < SMB30_PROT_ID)
@@ -8672,6 +8673,7 @@ bool smb3_11_final_sess_setup_resp(struct ksmbd_work *work)
rsp = ksmbd_resp_buf_next(work);
if (le16_to_cpu(rsp->Command) == SMB2_SESSION_SETUP_HE &&
+ sess->user && !user_guest(sess->user) &&
rsp->Status == STATUS_SUCCESS)
return true;
return false;
--
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