CIFS: Enable encryption during session setup phase

commit cabfb3680f78981d26c078a26e5c748531257ebb upstream.

In order to allow encryption on SMB connection we need to exchange
a session key and generate encryption and decryption keys.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
[bwh: Backported to 3.16:
 - SMB2_sess_establish_session() has not been split out from SMB2_sess_setup()
   and there is additional cleanup to do on error, so keep the
   'goto keygen_exit'
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 7426b06..d7218c1 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -343,13 +343,12 @@
 	/* BB is NTLMV2 session security format easier to use here? */
 	flags = NTLMSSP_NEGOTIATE_56 |	NTLMSSP_REQUEST_TARGET |
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
-		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC;
-	if (ses->server->sign) {
+		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
+		NTLMSSP_NEGOTIATE_SEAL;
+	if (ses->server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-		if (!ses->server->session_estab ||
-				ses->ntlmssp->sesskey_per_smbsess)
-			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
-	}
+	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
 
@@ -412,13 +411,12 @@
 	flags = NTLMSSP_NEGOTIATE_56 |
 		NTLMSSP_REQUEST_TARGET | NTLMSSP_NEGOTIATE_TARGET_INFO |
 		NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
-		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC;
-	if (ses->server->sign) {
+		NTLMSSP_NEGOTIATE_NTLM | NTLMSSP_NEGOTIATE_EXTENDED_SEC |
+		NTLMSSP_NEGOTIATE_SEAL;
+	if (ses->server->sign)
 		flags |= NTLMSSP_NEGOTIATE_SIGN;
-		if (!ses->server->session_estab ||
-				ses->ntlmssp->sesskey_per_smbsess)
-			flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
-	}
+	if (!ses->server->session_estab || ses->ntlmssp->sesskey_per_smbsess)
+		flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
 
 	tmp = *pbuffer + sizeof(AUTHENTICATE_MESSAGE);
 	sec_blob->NegotiateFlags = cpu_to_le32(flags);
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 219fdc0..6a5b702 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -764,10 +764,8 @@
 
 	if (!rc) {
 		mutex_lock(&server->srv_mutex);
-		if (server->sign && server->ops->generate_signingkey) {
+		if (server->ops->generate_signingkey) {
 			rc = server->ops->generate_signingkey(ses);
-			kfree(ses->auth_key.response);
-			ses->auth_key.response = NULL;
 			if (rc) {
 				cifs_dbg(FYI,
 					"SMB3 session key generation failed\n");
@@ -789,10 +787,6 @@
 	}
 
 keygen_exit:
-	if (!server->sign) {
-		kfree(ses->auth_key.response);
-		ses->auth_key.response = NULL;
-	}
 	kfree(ses->ntlmssp);
 
 	return rc;