cifs: Correctly set SMB1 SessionKey field in Session Setup Request

[MS-CIFS] specification in section 2.2.4.53.1 where is described
SMB_COM_SESSION_SETUP_ANDX Request, for SessionKey field says:

    The client MUST set this field to be equal to the SessionKey field in
    the SMB_COM_NEGOTIATE Response for this SMB connection.

Linux SMB client currently set this field to zero. This is working fine
against Windows NT SMB servers thanks to [MS-CIFS] product behavior <94>:

    Windows NT Server ignores the client's SessionKey.

For compatibility with [MS-CIFS], set this SessionKey field in Session
Setup Request to value retrieved from Negotiate response.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pali

fs/smb/client/cifsglob.h

@@ -773,6 +773,7 @@ struct TCP_Server_Info {
 	char workstation_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
 	__u32 sequence_number; /* for signing, protected by srv_mutex */
 	__u32 reconnect_instance; /* incremented on each reconnect */
+	__le32 session_key_id; /* retrieved from negotiate response and send in session setup request */
 	struct session_key session_key;
 	unsigned long lstrp; /* when we got last response from this server */
 	struct cifs_secmech secmech; /* crypto sec mech functs, descriptors */

fs/smb/client/cifspdu.h

@@ -597,7 +597,7 @@ typedef union smb_com_session_setup_andx {
 		__le16 MaxBufferSize;
 		__le16 MaxMpxCount;
 		__le16 VcNumber;
-		__u32 SessionKey;
+		__le32 SessionKey;
 		__le16 SecurityBlobLength;
 		__u32 Reserved;
 		__le32 Capabilities;	/* see below */
@@ -616,7 +616,7 @@ typedef union smb_com_session_setup_andx {
 		__le16 MaxBufferSize;
 		__le16 MaxMpxCount;
 		__le16 VcNumber;
-		__u32 SessionKey;
+		__le32 SessionKey;
 		__le16 CaseInsensitivePasswordLength; /* ASCII password len */
 		__le16 CaseSensitivePasswordLength; /* Unicode password length*/
 		__u32 Reserved;	/* see below */
@@ -654,7 +654,7 @@ typedef union smb_com_session_setup_andx {
 		__le16 MaxBufferSize;
 		__le16 MaxMpxCount;
 		__le16 VcNumber;
-		__u32 SessionKey;
+		__le32 SessionKey;
 		__le16 PasswordLength;
 		__u32 Reserved; /* encrypt key len and offset */
 		__le16 ByteCount;

fs/smb/client/cifssmb.c

@@ -498,6 +498,7 @@ CIFSSMBNegotiate(const unsigned int xid,
 	server->max_rw = le32_to_cpu(pSMBr->MaxRawSize);
 	cifs_dbg(NOISY, "Max buf = %d\n", ses->server->maxBuf);
 	server->capabilities = le32_to_cpu(pSMBr->Capabilities);
+	server->session_key_id = pSMBr->SessionKey;
 	server->timeAdj = (int)(__s16)le16_to_cpu(pSMBr->ServerTimeZone);
 	server->timeAdj *= 60;
 

fs/smb/client/sess.c

@@ -628,6 +628,7 @@ static __u32 cifs_ssetup_hdr(struct cifs_ses *ses,
 					USHRT_MAX));
 	pSMB->req.MaxMpxCount = cpu_to_le16(server->maxReq);
 	pSMB->req.VcNumber = cpu_to_le16(1);
+	pSMB->req.SessionKey = server->session_key_id;
 
 	/* Now no need to set SMBFLG_CASELESS or obsolete CANONICAL PATH */