SMB3: Fix 3.11 encryption to Windows and handle encrypted smb3 tcon

Temporarily disable AES-GCM, as AES-CCM is only currently
enabled mechanism on client side.  This fixes SMB3.11
encrypted mounts to Windows.

Also the tree connect request itself should be encrypted if
requested encryption ("seal" on mount), in addition we should be
enabling encryption in 3.11 based on whether we got any valid
encryption ciphers back in negprot (the corresponding session flag is
not set as it is in 3.0 and 3.02)
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
CC: Stable <stable@vger.kernel.org>

fs/cifs/connect.c

@@ -2959,6 +2959,22 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 		}
 	}
 
+	if (volume_info->seal) {
+		if (ses->server->vals->protocol_id == 0) {
+			cifs_dbg(VFS,
+				 "SMB3 or later required for encryption\n");
+			rc = -EOPNOTSUPP;
+			goto out_fail;
+		} else if (tcon->ses->server->capabilities &
+					SMB2_GLOBAL_CAP_ENCRYPTION)
+			tcon->seal = true;
+		else {
+			cifs_dbg(VFS, "Encryption is not supported on share\n");
+			rc = -EOPNOTSUPP;
+			goto out_fail;
+		}
+	}
+
 	/*
 	 * BB Do we need to wrap session_mutex around this TCon call and Unix
 	 * SetFS as we do on SessSetup and reconnect?
@@ -3007,22 +3023,6 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 		tcon->use_resilient = true;
 	}
 
-	if (volume_info->seal) {
-		if (ses->server->vals->protocol_id == 0) {
-			cifs_dbg(VFS,
-				 "SMB3 or later required for encryption\n");
-			rc = -EOPNOTSUPP;
-			goto out_fail;
-		} else if (tcon->ses->server->capabilities &
-					SMB2_GLOBAL_CAP_ENCRYPTION)
-			tcon->seal = true;
-		else {
-			cifs_dbg(VFS, "Encryption is not supported on share\n");
-			rc = -EOPNOTSUPP;
-			goto out_fail;
-		}
-	}
-
 	/*
 	 * We can have only one retry value for a connection to a share so for
 	 * resources mounted more than once to the same server share the last

fs/cifs/smb2pdu.c

@@ -383,10 +383,10 @@ static void
 build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
 {
 	pneg_ctxt->ContextType = SMB2_ENCRYPTION_CAPABILITIES;
-	pneg_ctxt->DataLength = cpu_to_le16(6);
-	pneg_ctxt->CipherCount = cpu_to_le16(2);
-	pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_GCM;
-	pneg_ctxt->Ciphers[1] = SMB2_ENCRYPTION_AES128_CCM;
+	pneg_ctxt->DataLength = cpu_to_le16(4); /* Cipher Count + le16 cipher */
+	pneg_ctxt->CipherCount = cpu_to_le16(1);
+/* pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_GCM;*/ /* not supported yet */
+	pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_CCM;
 }
 
 static void
@@ -444,6 +444,7 @@ static int decode_encrypt_ctx(struct TCP_Server_Info *server,
 		return -EINVAL;
 	}
 	server->cipher_type = ctxt->Ciphers[0];
+	server->capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
 	return 0;
 }
 

fs/cifs/smb2pdu.h

@@ -297,7 +297,7 @@ struct smb2_encryption_neg_context {
 	__le16	DataLength;
 	__le32	Reserved;
 	__le16	CipherCount; /* AES-128-GCM and AES-128-CCM */
-	__le16	Ciphers[2]; /* Ciphers[0] since only one used now */
+	__le16	Ciphers[1]; /* Ciphers[0] since only one used now */
 } __packed;
 
 struct smb2_negotiate_rsp {