linux-kernel - [PATCH 5.10 258/299] smb3: when mounting with multichannel include it in requested capabilities

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Date:   Mon, 10 May 2021 12:20:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Talpey <tom@...pey.com>,
        Shyam Prasad N <sprasad@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 5.10 258/299] smb3: when mounting with multichannel include it in requested capabilities

From: Steve French <stfrench@...rosoft.com>

commit 679971e7213174efb56abc8fab1299d0a88db0e8 upstream.

In the SMB3/SMB3.1.1 negotiate protocol request, we are supposed to
advertise CAP_MULTICHANNEL capability when establishing multiple
channels has been requested by the user doing the mount. See MS-SMB2
sections 2.2.3 and 3.2.5.2

Without setting it there is some risk that multichannel could fail
if the server interpreted the field strictly.

Reviewed-By: Tom Talpey <tom@...pey.com>
Reviewed-by: Shyam Prasad N <sprasad@...rosoft.com>
Cc: <stable@...r.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/cifs/smb2pdu.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -840,6 +840,8 @@ SMB2_negotiate(const unsigned int xid, s
 		req->SecurityMode = 0;
 
 	req->Capabilities = cpu_to_le32(server->vals->req_capabilities);
+	if (ses->chan_max > 1)
+		req->Capabilities |= cpu_to_le32(SMB2_GLOBAL_CAP_MULTI_CHANNEL);
 
 	/* ClientGUID must be zero for SMB2.02 dialect */
 	if (server->vals->protocol_id == SMB20_PROT_ID)
@@ -1025,6 +1027,9 @@ int smb3_validate_negotiate(const unsign
 
 	pneg_inbuf->Capabilities =
 			cpu_to_le32(server->vals->req_capabilities);
+	if (tcon->ses->chan_max > 1)
+		pneg_inbuf->Capabilities |= cpu_to_le32(SMB2_GLOBAL_CAP_MULTI_CHANNEL);
+
 	memcpy(pneg_inbuf->Guid, server->client_guid,
 					SMB2_CLIENT_GUID_SIZE);