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path: root/drivers/net/usb/qmi_wwan.c
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Diffstat (limited to 'drivers/net/usb/qmi_wwan.c')
-rw-r--r--drivers/net/usb/qmi_wwan.c104
1 files changed, 104 insertions, 0 deletions
diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index 968d5d50751d..2a3579f67910 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -13,6 +13,7 @@
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/ethtool.h>
+#include <linux/etherdevice.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
@@ -52,6 +53,96 @@ struct qmi_wwan_state {
struct usb_interface *data;
};
+/* default ethernet address used by the modem */
+static const u8 default_modem_addr[ETH_ALEN] = {0x02, 0x50, 0xf3};
+
+/* Make up an ethernet header if the packet doesn't have one.
+ *
+ * A firmware bug common among several devices cause them to send raw
+ * IP packets under some circumstances. There is no way for the
+ * driver/host to know when this will happen. And even when the bug
+ * hits, some packets will still arrive with an intact header.
+ *
+ * The supported devices are only capably of sending IPv4, IPv6 and
+ * ARP packets on a point-to-point link. Any packet with an ethernet
+ * header will have either our address or a broadcast/multicast
+ * address as destination. ARP packets will always have a header.
+ *
+ * This means that this function will reliably add the appropriate
+ * header iff necessary, provided our hardware address does not start
+ * with 4 or 6.
+ *
+ * Another common firmware bug results in all packets being addressed
+ * to 00:a0:c6:00:00:00 despite the host address being different.
+ * This function will also fixup such packets.
+ */
+static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+ __be16 proto;
+
+ /* usbnet rx_complete guarantees that skb->len is at least
+ * hard_header_len, so we can inspect the dest address without
+ * checking skb->len
+ */
+ switch (skb->data[0] & 0xf0) {
+ case 0x40:
+ proto = htons(ETH_P_IP);
+ break;
+ case 0x60:
+ proto = htons(ETH_P_IPV6);
+ break;
+ case 0x00:
+ if (is_multicast_ether_addr(skb->data))
+ return 1;
+ /* possibly bogus destination - rewrite just in case */
+ skb_reset_mac_header(skb);
+ goto fix_dest;
+ default:
+ /* pass along other packets without modifications */
+ return 1;
+ }
+ if (skb_headroom(skb) < ETH_HLEN)
+ return 0;
+ skb_push(skb, ETH_HLEN);
+ skb_reset_mac_header(skb);
+ eth_hdr(skb)->h_proto = proto;
+ memset(eth_hdr(skb)->h_source, 0, ETH_ALEN);
+fix_dest:
+ memcpy(eth_hdr(skb)->h_dest, dev->net->dev_addr, ETH_ALEN);
+ return 1;
+}
+
+/* very simplistic detection of IPv4 or IPv6 headers */
+static bool possibly_iphdr(const char *data)
+{
+ return (data[0] & 0xd0) == 0x40;
+}
+
+/* disallow addresses which may be confused with IP headers */
+static int qmi_wwan_mac_addr(struct net_device *dev, void *p)
+{
+ int ret;
+ struct sockaddr *addr = p;
+
+ ret = eth_prepare_mac_addr_change(dev, p);
+ if (ret < 0)
+ return ret;
+ if (possibly_iphdr(addr->sa_data))
+ return -EADDRNOTAVAIL;
+ eth_commit_mac_addr_change(dev, p);
+ return 0;
+}
+
+static const struct net_device_ops qmi_wwan_netdev_ops = {
+ .ndo_open = usbnet_open,
+ .ndo_stop = usbnet_stop,
+ .ndo_start_xmit = usbnet_start_xmit,
+ .ndo_tx_timeout = usbnet_tx_timeout,
+ .ndo_change_mtu = usbnet_change_mtu,
+ .ndo_set_mac_address = qmi_wwan_mac_addr,
+ .ndo_validate_addr = eth_validate_addr,
+};
+
/* using a counter to merge subdriver requests with our own into a combined state */
static int qmi_wwan_manage_power(struct usbnet *dev, int on)
{
@@ -229,6 +320,18 @@ next_desc:
usb_driver_release_interface(driver, info->data);
}
+ /* Never use the same address on both ends of the link, even
+ * if the buggy firmware told us to.
+ */
+ if (!compare_ether_addr(dev->net->dev_addr, default_modem_addr))
+ eth_hw_addr_random(dev->net);
+
+ /* make MAC addr easily distinguishable from an IP header */
+ if (possibly_iphdr(dev->net->dev_addr)) {
+ dev->net->dev_addr[0] |= 0x02; /* set local assignment bit */
+ dev->net->dev_addr[0] &= 0xbf; /* clear "IP" bit */
+ }
+ dev->net->netdev_ops = &qmi_wwan_netdev_ops;
err:
return status;
}
@@ -307,6 +410,7 @@ static const struct driver_info qmi_wwan_info = {
.bind = qmi_wwan_bind,
.unbind = qmi_wwan_unbind,
.manage_power = qmi_wwan_manage_power,
+ .rx_fixup = qmi_wwan_rx_fixup,
};
#define HUAWEI_VENDOR_ID 0x12D1