[drmkms] Properly get dri name for file access. Some additional secur…

…ity checks.

custom_video_drmkms.cpp

@@ -223,6 +223,13 @@ bool drmkms_timing::test_kernel_user_modes()
 	// Count the number of existing modes, so it should be +1 when attaching
 	// a new mode. Could also check the mode name, still better
 	conn = drmModeGetConnector(fd, m_desktop_output);
+	if (!conn)
+	{
+		log_verbose("DRM/KMS: <%d> (%s) Cannot get connector\n", m_id, __FUNCTION__);
+		m_kernel_user_modes = false;
+		return false;
+	}
+
 	first_modes_count = conn->count_modes;
 	ret = drmModeAttachMode(fd, m_desktop_output, &mode);
 	drmModeFreeConnector(conn);
@@ -568,8 +575,8 @@ bool drmkms_timing::init()
 	int output_position = 0;
 	for (int num = 0; num < num_devices; num++)
 	{
-		// Ignore render nodes
-		if (devices[num]->available_nodes & 1 << DRM_NODE_PRIMARY)
+		// Skip non-primary nodes
+		if (devices[num]->available_nodes & (1 << DRM_NODE_PRIMARY))
 			drm_name = devices[num]->nodes[DRM_NODE_PRIMARY];
 		else continue;
 
@@ -589,7 +596,10 @@ bool drmkms_timing::init()
 			log_error("DRM/KMS: <%d> (init) [ERROR] ioctl DRM_CAP_DUMB_BUFFER\n", m_id);
 
 		if (!check_dumb)
+		{
 			log_error("DRM/KMS: <%d> (init) [ERROR] dumb buffer not supported\n", m_id);
+			continue;
+		}
 
 		p_res = drmModeGetResources(m_drm_fd);
 
@@ -617,6 +627,7 @@ bool drmkms_timing::init()
 					}
 					m_desktop_output = p_connector->connector_id;
 					m_card_id = num;
+					strcpy(m_drm_name, drm_name);
 					log_verbose("DRM/KMS: <%d> (init) card %d connector %d id %d name %s selected as primary output\n", m_id, num, i, m_desktop_output, connector_name);
 
 					drmModeEncoder *p_encoder = drmModeGetEncoder(m_drm_fd, p_connector->encoder_id);
@@ -684,9 +695,14 @@ bool drmkms_timing::init()
 						s_shared_count[m_card_id] = 2;
 					}
 					if (!drmIsMaster(m_drm_fd))
+					{
+						m_desktop_output = 0;
 						log_error("DRM/KMS: <%d> (%s) [ERROR] limited DRM rights on this screen\n", m_id, __FUNCTION__);
+					}
 				}
 			}
+			// If we're here and we have a valid output, we're done.
+			if (m_desktop_output) break;
 		}
 	}
 
@@ -756,10 +772,9 @@ int drmkms_timing::get_master_fd()
 		return -1;
 	}
 
-	snprintf(dev_path, path_length, "/dev/dri/card%d", m_card_id);
-	if (!access(dev_path, F_OK) == 0)
+	if (!access(m_drm_name, F_OK) == 0)
 	{
-		log_error("DRM/KMS: <%d> (%s) [ERROR] Device %s doesn't exist\n", m_id, __FUNCTION__, dev_path);
+		log_error("DRM/KMS: <%d> (%s) [ERROR] Device %s doesn't exist\n", m_id, __FUNCTION__, m_drm_name);
 		return -1;
 	}
 
@@ -805,16 +820,16 @@ int drmkms_timing::get_master_fd()
 
 	// CASE 3: m_drm_fd is not a master (and probably not even a valid FD), the currend pid doesn't have master rights
 	// Or master is owned by a 3rd party app (like a frontend ...)
-	log_verbose("DRM/KMS: <%d> (%s) Couldn't find a master FD, opening default /dev/dri/card%d\n", m_id, __FUNCTION__, m_card_id);
+	log_verbose("DRM/KMS: <%d> (%s) Couldn't find a master FD, opening default %s\n", m_id, __FUNCTION__, m_drm_name);
 
 	// mark our former hook as invalid
 	m_hook_fd = -1;
 
-	fd = open(dev_path, O_RDWR | O_CLOEXEC);
+	fd = open(m_drm_name, O_RDWR | O_CLOEXEC);
 	if (fd < 0)
 	{
 		// Oh, we're totally screwed here, worst possible scenario
-		log_error("DRM/KMS: <%d> (%s) Can't open /dev/dri/card%d, can't get master rights\n", m_id, __FUNCTION__, m_card_id);
+		log_error("DRM/KMS: <%d> (%s) Can't open %s, can't get master rights\n", m_id, __FUNCTION__, m_drm_name);
 		return -1;
 	}
 

custom_video_drmkms.h

@@ -53,6 +53,7 @@ class drmkms_timing : public custom_video
 		int m_caps = 0;
 
 		char m_device_name[32];
+		char m_drm_name[32];
 		unsigned int m_desktop_output = 0;
 		int m_video_modes_position = 0;