From 813afe206c8ff10cbbe715bf94980bf8ba6be70f Mon Sep 17 00:00:00 2001

From: Victor Toso <victortoso@redhat.com>

Date: Thu, 22 Dec 2022 16:13:08 +0100

Subject: [PATCH 7/8] usbredirect: allow multiple devices by vendor:product

Currently, if an user tries to redirect two devices with the same

vendor:product info, the second instance of usbredirect will not

succeed, leading to a segmentation fault.

The core of the problem is that usbredirect is using

libusb_open_device_with_vid_pid() which always returns the first

instance of a given vendor:product, leading the second instance of

usbredirect to give an usb device that is in use to usbredirhost.

This patch fixes the situation, making it possible to run usbredirect

with --device $vendor:$product multiple times. We do a early check

that we can claim the usb device, prior to handle it over to

usbredirhost.

Related: https://gitlab.freedesktop.org/spice/usbredir/-/issues/29

Signed-off-by: Victor Toso <victortoso@redhat.com>

---

 tools/usbredirect.c | 90 ++++++++++++++++++++++++++++++++++++++++++---

 1 file changed, 85 insertions(+), 5 deletions(-)

diff --git a/tools/usbredirect.c b/tools/usbredirect.c

index 95f3580..0b04418 100644

--- a/tools/usbredirect.c

+++ b/tools/usbredirect.c

@@ -466,6 +466,90 @@ signal_handler(gpointer user_data)

 }

 #endif

+static bool

+can_claim_usb_device(libusb_device *dev, libusb_device_handle **handle)

+{

+    int ret = libusb_open(dev, handle);

+    if (ret != 0) {

+        g_debug("Failed to open device");

+        return false;

+    }

+

+    /* Opening is not enough. We need to check if device can be claimed

+     * for I/O operations */

+    struct libusb_config_descriptor *config = NULL;

+    ret = libusb_get_active_config_descriptor(dev, &config);

+    if (ret != 0 || config == NULL) {

+        g_debug("Failed to get active descriptor");

+        *handle = NULL;

+        return false;

+    }

+

+#if LIBUSBX_API_VERSION >= 0x01000102

+    libusb_set_auto_detach_kernel_driver(*handle, 1);

+#endif

+

+    int i;

+    for (i = 0; i < config->bNumInterfaces; i++) {

+        int interface_num = config->interface[i].altsetting[0].bInterfaceNumber;

+#if LIBUSBX_API_VERSION < 0x01000102

+        ret = libusb_detach_kernel_driver(handle, interface_num);

+        if (ret != 0 && ret != LIBUSB_ERROR_NOT_FOUND

+            && ret != LIBUSB_ERROR_NOT_SUPPORTED) {

+            g_error("failed to detach driver from interface %d: %s",

+                    interface_num, libusb_error_name(ret));

+            *handle = NULL;

+            break

+        }

+#endif

+        ret = libusb_claim_interface(*handle, interface_num);

+        if (ret != 0) {

+            g_debug("Could not claim interface");

+            *handle = NULL;

+            break;

+        }

+        ret = libusb_release_interface(*handle, interface_num);

+        if (ret != 0) {

+            g_debug("Could not release interface");

+            *handle = NULL;

+            break;

+        }

+    }

+

+    libusb_free_config_descriptor(config);

+    return *handle != NULL;

+}

+

+static libusb_device_handle *

+open_usb_device(redirect *self)

+{

+    struct libusb_device **devs;

+    struct libusb_device_handle *dev_handle = NULL;

+    size_t i, ndevices;

+

+    ndevices = libusb_get_device_list(NULL, &devs);

+    for (i = 0; i < ndevices; i++) {

+        struct libusb_device_descriptor desc;

+        if (libusb_get_device_descriptor(devs[i], &desc) != 0) {

+            g_warning("Failed to get descriptor");

+            continue;

+        }

+

+        if (self->device.vendor != desc.idVendor ||

+            self->device.product != desc.idProduct) {

+            continue;

+        }

+

+        if (can_claim_usb_device(devs[i], &dev_handle)) {

+            break;

+        }

+    }

+

+    libusb_free_device_list(devs, 1);

+    return dev_handle;

+}

+

+

 static gboolean

 connection_incoming_cb(GSocketService    *service,

                        GSocketConnection *client_connection,

@@ -515,11 +599,7 @@ main(int argc, char *argv[])

     g_unix_signal_add(SIGTERM, signal_handler, self);

 #endif

-    /* This is binary is not meant to support plugins so it is safe to pass

-     * NULL as libusb_context here and all subsequent calls */

-    libusb_device_handle *device_handle = libusb_open_device_with_vid_pid(NULL,

-            self->device.vendor,

-            self->device.product);

+    libusb_device_handle *device_handle = open_usb_device(self);

     if (!device_handle) {

         g_printerr("Failed to open device!\n");

         goto err_init;

-- 

2.39.0