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ksmbd: do not sign response to session request for guest login

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commit 5fde3c21cf33830eda7bfd006dc7f4bf07ec9fe6 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Marios Makassikis 2023-01-11 17:39:02 +01:00 committed by Greg Kroah-Hartman
parent 4210c3555d
commit 87a7f38a90
1 changed files with 2 additions and 0 deletions
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2
fs/ksmbd/smb2pdu.c
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@ -8613,6 +8613,7 @@ 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 = work->response_buf;
if (conn->dialect < SMB30_PROT_ID)
@ -8622,6 +8623,7 @@ 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;