1 files changed, 153 insertions, 0 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index ea681f157368..0406a59f0551 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -12,6 +12,7 @@
 #include <linux/nls.h>
 #include <linux/device.h>
 #include <linux/scatterlist.h>
+#include <linux/usb/cdc.h>
 #include <linux/usb/quirks.h>
 #include <linux/usb/hcd.h>      /* for usbcore internals */
 #include <asm/byteorder.h>
@@ -2023,3 +2024,155 @@ int usb_driver_set_configuration(struct usb_device *udev, int config)
         return 0;
 }
 EXPORT_SYMBOL_GPL(usb_driver_set_configuration);
+
+/**
+ * cdc_parse_cdc_header - parse the extra headers present in CDC devices
+ * @hdr: the place to put the results of the parsing
+ * @intf: the interface for which parsing is requested
+ * @buffer: pointer to the extra headers to be parsed
+ * @buflen: length of the extra headers
+ *
+ * This evaluates the extra headers present in CDC devices which
+ * bind the interfaces for data and control and provide details
+ * about the capabilities of the device.
+ *
+ * Return: number of descriptors parsed or -EINVAL
+ * if the header is contradictory beyond salvage
+ */
+
+int cdc_parse_cdc_header(struct usb_cdc_parsed_header *hdr,
+                                struct usb_interface *intf,
+                                u8 *buffer,
+                                int buflen)
+{
+        /* duplicates are ignored */
+        struct usb_cdc_union_desc *union_header = NULL;
+
+        /* duplicates are not tolerated */
+        struct usb_cdc_header_desc *header = NULL;
+        struct usb_cdc_ether_desc *ether = NULL;
+        struct usb_cdc_mdlm_detail_desc *detail = NULL;
+        struct usb_cdc_mdlm_desc *desc = NULL;
+
+        unsigned int elength;
+        int cnt = 0;
+
+        memset(hdr, 0x00, sizeof(struct usb_cdc_parsed_header));
+        hdr->phonet_magic_present = false;
+        while (buflen > 0) {
+                elength = buffer[0];
+                if (!elength) {
+                        dev_err(&intf->dev, "skipping garbage byte\n");
+                        elength = 1;
+                        goto next_desc;
+                }
+                if (buffer[1] != USB_DT_CS_INTERFACE) {
+                        dev_err(&intf->dev, "skipping garbage\n");
+                        goto next_desc;
+                }
+
+                switch (buffer[2]) {
+                case USB_CDC_UNION_TYPE: /* we've found it */
+                        if (elength < sizeof(struct usb_cdc_union_desc))
+                                goto next_desc;
+                        if (union_header) {
+                                dev_err(&intf->dev, "More than one union descriptor, skipping ...\n");
+                                goto next_desc;
+                        }
+                        union_header = (struct usb_cdc_union_desc *)buffer;
+                        break;
+                case USB_CDC_COUNTRY_TYPE:
+                        if (elength < sizeof(struct usb_cdc_country_functional_desc))
+                                goto next_desc;
+                        hdr->usb_cdc_country_functional_desc =
+                                (struct usb_cdc_country_functional_desc *)buffer;
+                        break;
+                case USB_CDC_HEADER_TYPE:
+                        if (elength != sizeof(struct usb_cdc_header_desc))
+                                goto next_desc;
+                        if (header)
+                                return -EINVAL;
+                        header = (struct usb_cdc_header_desc *)buffer;
+                        break;
+                case USB_CDC_ACM_TYPE:
+                        if (elength < sizeof(struct usb_cdc_acm_descriptor))
+                                goto next_desc;
+                        hdr->usb_cdc_acm_descriptor =
+                                (struct usb_cdc_acm_descriptor *)buffer;
+                        break;
+                case USB_CDC_ETHERNET_TYPE:
+                        if (elength != sizeof(struct usb_cdc_ether_desc))
+                                goto next_desc;
+                        if (ether)
+                                return -EINVAL;
+                        ether = (struct usb_cdc_ether_desc *)buffer;
+                        break;
+                case USB_CDC_CALL_MANAGEMENT_TYPE:
+                        if (elength < sizeof(struct usb_cdc_call_mgmt_descriptor))
+                                goto next_desc;
+                        hdr->usb_cdc_call_mgmt_descriptor =
+                                (struct usb_cdc_call_mgmt_descriptor *)buffer;
+                        break;
+                case USB_CDC_DMM_TYPE:
+                        if (elength < sizeof(struct usb_cdc_dmm_desc))
+                                goto next_desc;
+                        hdr->usb_cdc_dmm_desc =
+                                (struct usb_cdc_dmm_desc *)buffer;
+                        break;
+                case USB_CDC_MDLM_TYPE:
+                        if (elength < sizeof(struct usb_cdc_mdlm_desc *))
+                                goto next_desc;
+                        if (desc)
+                                return -EINVAL;
+                        desc = (struct usb_cdc_mdlm_desc *)buffer;
+                        break;
+                case USB_CDC_MDLM_DETAIL_TYPE:
+                        if (elength < sizeof(struct usb_cdc_mdlm_detail_desc *))
+                                goto next_desc;
+                        if (detail)
+                                return -EINVAL;
+                        detail = (struct usb_cdc_mdlm_detail_desc *)buffer;
+                        break;
+                case USB_CDC_NCM_TYPE:
+                        if (elength < sizeof(struct usb_cdc_ncm_desc))
+                                goto next_desc;
+                        hdr->usb_cdc_ncm_desc = (struct usb_cdc_ncm_desc *)buffer;
+                        break;
+                case USB_CDC_MBIM_TYPE:
+                        if (elength < sizeof(struct usb_cdc_mbim_desc))
+                                goto next_desc;
+
+                        hdr->usb_cdc_mbim_desc = (struct usb_cdc_mbim_desc *)buffer;
+                        break;
+                case USB_CDC_MBIM_EXTENDED_TYPE:
+                        if (elength < sizeof(struct usb_cdc_mbim_extended_desc))
+                                break;
+                        hdr->usb_cdc_mbim_extended_desc =
+                                (struct usb_cdc_mbim_extended_desc *)buffer;
+                        break;
+                case CDC_PHONET_MAGIC_NUMBER:
+                        hdr->phonet_magic_present = true;
+                        break;
+                default:
+                        /*
+                         * there are LOTS more CDC descriptors that
+                         * could legitimately be found here.
+                         */
+                        dev_dbg(&intf->dev, "Ignoring descriptor: type %02x, length %ud\n",
+                                        buffer[2], elength);
+                        goto next_desc;
+                }
+                cnt++;
+next_desc:
+                buflen -= elength;
+                buffer += elength;
+        }
+        hdr->usb_cdc_union_desc = union_header;
+        hdr->usb_cdc_header_desc = header;
+        hdr->usb_cdc_mdlm_detail_desc = detail;
+        hdr->usb_cdc_mdlm_desc = desc;
+        hdr->usb_cdc_ether_desc = ether;
+        return cnt;
+}
+
+EXPORT_SYMBOL(cdc_parse_cdc_header);