ksmbd: set SMB2_SESSION_FLAG_ENCRYPT_DATA when enforcing data encryption for this share

Currently, SMB2_SESSION_FLAG_ENCRYPT_DATA is always set session setup
response. Since this forces data encryption from the client, there is a
problem that data is always encrypted regardless of the use of the cifs
seal mount option. SMB2_SESSION_FLAG_ENCRYPT_DATA should be set according
to KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION flags, and in case of
KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF, encryption mode is turned off for
all connections.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/ksmbd_netlink.h

@@ -74,6 +74,7 @@ struct ksmbd_heartbeat {
 #define KSMBD_GLOBAL_FLAG_SMB2_LEASES		BIT(0)
 #define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION	BIT(1)
 #define KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL	BIT(2)
+#define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF	BIT(3)
 
 /*
  * IPC request for ksmbd server startup

fs/ksmbd/smb2ops.c

@@ -247,8 +247,9 @@ void init_smb3_02_server(struct ksmbd_conn *conn)
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_LEASING;
 
-	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION &&
-	    conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION)
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION ||
+	    (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF) &&
+	     conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION))
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
 
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
@@ -271,6 +272,11 @@ int init_smb3_11_server(struct ksmbd_conn *conn)
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_LEASING;
 
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION ||
+	    (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF) &&
+	     conn->cli_cap & SMB2_GLOBAL_CAP_ENCRYPTION))
+		conn->vals->capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
+
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
 

fs/ksmbd/smb2pdu.c

@@ -903,7 +903,7 @@ static void decode_encrypt_ctxt(struct ksmbd_conn *conn,
 		return;
 	}
 
-	if (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION))
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF)
 		return;
 
 	for (i = 0; i < cph_cnt; i++) {
@@ -1508,7 +1508,8 @@ static int ntlm_authenticate(struct ksmbd_work *work)
 			return -EINVAL;
 		}
 		sess->enc = true;
-		rsp->SessionFlags = SMB2_SESSION_FLAG_ENCRYPT_DATA_LE;
+		if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION)
+			rsp->SessionFlags = SMB2_SESSION_FLAG_ENCRYPT_DATA_LE;
 		/*
 		 * signing is disable if encryption is enable
 		 * on this session
@@ -1599,7 +1600,8 @@ static int krb5_authenticate(struct ksmbd_work *work)
 			return -EINVAL;
 		}
 		sess->enc = true;
-		rsp->SessionFlags = SMB2_SESSION_FLAG_ENCRYPT_DATA_LE;
+		if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION)
+			rsp->SessionFlags = SMB2_SESSION_FLAG_ENCRYPT_DATA_LE;
 		sess->sign = false;
 	}