这个内核代码实现了哪些功能：
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Host Side support for RNDIS Networking Links
* Copyright (C) 2005 by David Brownell
*/
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/usb/rndis_host.h>
/*
* RNDIS is NDIS remoted over USB. It's a MSFT variant of CDC ACM ... of
* course ACM was intended for modems, not Ethernet links! USB's standard
* for Ethernet links is "CDC Ethernet", which is significantly simpler.
*
* NOTE that Microsoft's "RNDIS 1.0" specification is incomplete. Issues
* include:
* - Power management in particular relies on information that's scattered
* through other documentation, and which is incomplete or incorrect even
* there.
* - There are various undocumented protocol requirements, such as the
* need to send unused garbage in control-OUT messages.
* - In some cases, MS-Windows will emit undocumented requests; this
* matters more to peripheral implementations than host ones.
*
* Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
*
* For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
* favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
* currently rare) "Ethernet Emulation Model" (EEM).
*/
/*
* RNDIS notifications from device: command completion; "reverse"
* keepalives; etc
*/
void rndis_status(struct usbnet *dev, struct urb *urb)
{
netdev_dbg(dev->net, "rndis status urb, len %d stat %d\n",
urb->actual_length, urb->status);
// FIXME for keepalives, respond immediately (asynchronously)
// if not an RNDIS status, do like cdc_status(dev,urb) does
}
EXPORT_SYMBOL_GPL(rndis_status);
/*
* RNDIS indicate messages.
*/
static void rndis_msg_indicate(struct usbnet *dev, struct rndis_indicate *msg,
int buflen)
{
struct cdc_state *info = (void *)&dev->data;
struct device *udev = &info->control->dev;
if (dev->driver_info->indication) {
dev->driver_info->indication(dev, msg, buflen);
} else {
u32 status = le32_to_cpu(msg->status);
switch (status) {
case RNDIS_STATUS_MEDIA_CONNECT:
dev_info(udev, "rndis media connect\n");
break;
case RNDIS_STATUS_MEDIA_DISCONNECT:
dev_info(udev, "rndis media disconnect\n");
break;
default:
dev_info(udev, "rndis indication: 0x%08x\n", status);
}
}
}
/*
* RPC done RNDIS-style. Caller guarantees:
* - message is properly byteswapped
* - there's no other request pending
* - buf can hold up to 1KB response (required by RNDIS spec)
* On return, the first few entries are already byteswapped.
*
* Call context is likely probe(), before interface name is known,
* which is why we won't try to use it in the diagnostics.
*/
int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf, int buflen)
{
struct cdc_state *info = (void *) &dev->data;
struct usb_cdc_notification notification;
int master_ifnum;
int retval;
int partial;
unsigned count;
u32 xid = 0, msg_len, request_id, msg_type, rsp,
status;
/* REVISIT when this gets called from contexts other than probe() or
* disconnect(): either serialize, or dispatch responses on xid
*/
msg_type = le32_to_cpu(buf->msg_type);
/* Issue the request; xid is unique, don't bother byteswapping it */
if (likely(msg_type != RNDIS_MSG_HALT && msg_type != RNDIS_MSG_RESET)) {
xid = dev->xid++;
if (!xid)
xid = dev->xid++;
buf->request_id = (__force __le32) xid;
}
master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
retval = usb_control_msg(dev->udev,
usb_sndctrlpipe(dev->udev, 0),
USB_CDC_SEND_ENCAPSULATED_COMMAND,
USB_TYPE_CLASS | USB_RECIP_INTERFACE,
0, master_ifnum,
buf, le32_to_cpu(buf->msg_len),
RNDIS_CONTROL_TIMEOUT_MS);
if (unlikely(retval < 0 || xid == 0))
return retval;
/* Some devices don't respond on the control channel until
* polled on the status channel, so do that first. */
if (dev->driver_info->data & RNDIS_DRIVER_DATA_POLL_STATUS) {
retval = usb_interrupt_msg(
dev->udev,
usb_rcvintpipe(dev->udev,
dev->status->desc.bEndpointAddress),
¬ification, sizeof(notification), &partial,
RNDIS_CONTROL_TIMEOUT_MS);
if (unlikely(retval < 0))
return retval;
}
/* Poll the control channel; the request probably completed immediately */
rsp = le32_to_cpu(buf->msg_type) | RNDIS_MSG_COMPLETION;
for (count = 0; count < 10; count++) {
memset(buf, 0, CONTROL_BUFFER_SIZE);
retval = usb_control_msg(dev->udev,
usb_rcvctrlpipe(dev->udev, 0),
USB_CDC_GET_ENCAPSULATED_RESPONSE,
USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
0, master_ifnum,
buf, buflen,
RNDIS_CONTROL_TIMEOUT_MS);
if (likely(retval >= 8)) {
msg_type = le32_to_cpu(buf->msg_type);
msg_len = le32_to_cpu(buf->msg_len);
status = le32_to_cpu(buf->status);
request_id = (__force u32) buf->request_id;
if (likely(msg_type == rsp)) {
if (likely(request_id == xid)) {
if (unlikely(rsp == RNDIS_MSG_RESET_C))
return 0;
if (likely(RNDIS_STATUS_SUCCESS ==
status))
return 0;
dev_dbg(&info->control->dev,
"rndis reply status %08x\n",
status);
return -EL3RST;
}
dev_dbg(&info->control->dev,
"rndis reply id %d expected %d\n",
request_id, xid);
/* then likely retry */
} else switch (msg_type) {
case RNDIS_MSG_INDICATE: /* fault/event */
rndis_msg_indicate(dev, (void *)buf, buflen);
break;
case RNDIS_MSG_KEEPALIVE: { /* ping */
struct rndis_keepalive_c *msg = (void *)buf;
msg->msg_type = cpu_to_le32(RNDIS_MSG_KEEPALIVE_C);
msg->msg_len = cpu_to_le32(sizeof *msg);
msg->status = cpu_to_le32(RNDIS_STATUS_SUCCESS);
retval = usb_control_msg(dev->udev,
usb_sndctrlpipe(dev->udev, 0),
USB_CDC_SEND_ENCAPSULATED_COMMAND,
USB_TYPE_CLASS | USB_RECIP_INTERFACE,
0, master_ifnum,
msg, sizeof *msg,
RNDIS_CONTROL_TIMEOUT_MS);
if (unlikely(retval < 0))
dev_dbg(&info->control->dev,
"rndis keepalive err %d\n",
retval);
}
break;
default:
dev_dbg(&info->control->dev,
"unexpected rndis msg %08x len %d\n",
le32_to_cpu(buf->msg_type), msg_len);
}
} else {
/* device probably issued a protocol stall; ignore */
dev_dbg(&info->control->dev,
"rndis response error, code %d\n", retval);
}
msleep(40);
}
dev_dbg(&info->control->dev, "rndis response timeout\n");
return -ETIMEDOUT;
}
EXPORT_SYMBOL_GPL(rndis_command);
/*
* rndis_query:
*
* Performs a query for @oid along with 0 or more bytes of payload as
* specified by @in_len. If @reply_len is not set to -1 then the reply
* length is checked against this value, resulting in an error if it
* doesn't match.
*
* NOTE: Adding a payload exactly or greater than the size of the expected
* response payload is an evident requirement MSFT added for ActiveSync.
*
* The only exception is for OIDs that return a variably sized response,
* in which case no payload should be added. This undocumented (and
* nonsensical!) issue was found by sniffing protocol requests from the
* ActiveSync 4.1 Windows driver.
*/
static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
void *buf, u32 oid, u32 in_len,
void **reply, int *reply_len)
{
int retval;
union {
void *buf;
struct rndis_msg_hdr *header;
struct rndis_query *get;
struct rndis_query_c *get_c;
} u;
u32 off, len;
u.buf = buf;
memset(u.get, 0, sizeof *u.get + in_len);
u.get->msg_type = cpu_to_le32(RNDIS_MSG_QUERY);
u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
u.get->oid = cpu_to_le32(oid);
u.get->len = cpu_to_le32(in_len);
u.get->offset = cpu_to_le32(20);
retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
if (unlikely(retval < 0)) {
dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
oid, retval);
return retval;
}
off = le32_to_cpu(u.get_c->offset);
len = le32_to_cpu(u.get_c->len);
if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
goto response_error;
if (*reply_len != -1 && len != *reply_len)
goto response_error;
*reply = (unsigned char *) &u.get_c->request_id + off;
*reply_len = len;
return retval;
response_error:
dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
"invalid response - off %d len %d\n",
oid, off, len);
return -EDOM;
}
/* same as usbnet_netdev_ops but MTU change not allowed */
static const struct net_device_ops rndis_netdev_ops = {
.ndo_open = usbnet_open,
.ndo_stop = usbnet_stop,
.ndo_start_xmit = usbnet_start_xmit,
.ndo_tx_timeout = usbnet_tx_timeout,
.ndo_get_stats64 = usbnet_get_stats64,
.ndo_set_mac_address = eth_mac_addr,
.ndo_validate_addr = eth_validate_addr,
};
int
generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
{
int retval;
struct net_device *net = dev->net;
struct cdc_state *info = (void *) &dev->data;
union {
void *buf;
struct rndis_msg_hdr *header;
struct rndis_init *init;
struct rndis_init_c *init_c;
struct rndis_query *get;
struct rndis_query_c *get_c;
struct rndis_set *set;
struct rndis_set_c *set_c;
struct rndis_halt *halt;
} u;
u32 tmp;
__le32 phym_unspec, *phym;
int reply_len;
unsigned char *bp;
/* we can't rely on i/o from stack working, or stack allocation */
u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
if (!u.buf)
return -ENOMEM;
retval = usbnet_generic_cdc_bind(dev, intf);
if (retval < 0)
goto fail;
u.init->msg_type = cpu_to_le32(RNDIS_MSG_INIT);
u.init->msg_len = cpu_to_le32(sizeof *u.init);
u.init->major_version = cpu_to_le32(1);
u.init->minor_version = cpu_to_le32(0);
/* max transfer (in spec) is 0x4000 at full speed, but for
* TX we'll stick to one Ethernet packet plus RNDIS framing.
* For RX we handle drivers that zero-pad to end-of-packet.
* Don't let userspace change these settings.
*
* NOTE: there still seems to be wierdness here, as if we need
* to do some more things to make sure WinCE targets accept this.
* They default to jumbograms of 8KB or 16KB, which is absurd
* for such low data rates and which is also more than Linux
* can usually expect to allocate for SKB data...
*/
net->hard_header_len += sizeof (struct rndis_data_hdr);
dev->hard_mtu = net->mtu + net->hard_header_len;
dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
if (dev->maxpacket == 0) {
netif_dbg(dev, probe, dev->net,
"dev->maxpacket can't be 0\n");
retval = -EINVAL;
goto fail_and_release;
}
dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
dev->rx_urb_size &= ~(dev->maxpacket - 1);
u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
net->netdev_ops = &rndis_netdev_ops;
retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
if (unlikely(retval < 0)) {
/* it might not even be an RNDIS device!! */
dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
goto fail_and_release;
}
tmp = le32_to_cpu(u.init_c->max_transfer_size);
if (tmp < dev->hard_mtu) {
if (tmp <= net->hard_header_len) {
dev_err(&intf->dev,
"dev can't take %u byte packets (max %u)\n",
dev->hard_mtu, tmp);
retval = -EINVAL;
goto halt_fail_and_release;
}
dev_warn(&intf->dev,
"dev can't take %u byte packets (max %u), "
"adjusting MTU to %u\n",
dev->hard_mtu, tmp, tmp - net->hard_header_len);
dev->hard_mtu = tmp;
net->mtu = dev->hard_mtu - net->hard_header_len;
}
/* REVISIT: peripheral "alignment" request is ignored ... */
dev_dbg(&intf->dev,
"hard mtu %u (%u from dev), rx buflen %zu, align %d\n",
dev->hard_mtu, tmp, dev->rx_urb_size,
1 << le32_to_cpu(u.init_c->packet_alignment));
/* module has some device initialization code needs to be done right
* after RNDIS_INIT */
if (dev->driver_info->early_init &&
dev->driver_info->early_init(dev) != 0)
goto halt_fail_and_release;
/* Check physical medium */
phym = NULL;
reply_len = sizeof *phym;
retval = rndis_query(dev, intf, u.buf,
RNDIS_OID_GEN_PHYSICAL_MEDIUM,
reply_len, (void **)&phym, &reply_len);
if (retval != 0 || !phym) {
/* OID is optional so don't fail here. */
phym_unspec = cpu_to_le32(RNDIS_PHYSICAL_MEDIUM_UNSPECIFIED);
phym = &phym_unspec;
}
if ((flags & FLAG_RNDIS_PHYM_WIRELESS) &&
le32_to_cpup(phym) != RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
netif_dbg(dev, probe, dev->net,
"driver requires wireless physical medium, but device is not\n");
retval = -ENODEV;
goto halt_fail_and_release;
}
if ((flags & FLAG_RNDIS_PHYM_NOT_WIRELESS) &&
le32_to_cpup(phym) == RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
netif_dbg(dev, probe, dev->net,
"driver requires non-wireless physical medium, but device is wireless.\n");
retval = -ENODEV;
goto halt_fail_and_release;
}
/* Get designated host ethernet address */
reply_len = ETH_ALEN;
retval = rndis_query(dev, intf, u.buf,
RNDIS_OID_802_3_PERMANENT_ADDRESS,
48, (void **) &bp, &reply_len);
if (unlikely(retval< 0)) {
dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
goto halt_fail_and_release;
}
if (bp[0] & 0x02)
eth_hw_addr_random(net);
else
ether_addr_copy(net->dev_addr, bp);
/* set a nonzero filter to enable data transfers */
memset(u.set, 0, sizeof *u.set);
u.set->msg_type = cpu_to_le32(RNDIS_MSG_SET);
u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
u.set->oid = cpu_to_le32(RNDIS_OID_GEN_CURRENT_PACKET_FILTER);
u.set->len = cpu_to_le32(4);
u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
*(__le32 *)(u.buf + sizeof *u.set) = cpu_to_le32(RNDIS_DEFAULT_FILTER);
retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
if (unlikely(retval < 0)) {
dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
goto halt_fail_and_release;
}
retval = 0;
kfree(u.buf);
return retval;
halt_fail_and_release:
memset(u.halt, 0, sizeof *u.halt);
u.halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
(void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
fail_and_release:
usb_set_intfdata(info->data, NULL);
usb_driver_release_interface(driver_of(intf), info->data);
info->data = NULL;
fail:
kfree(u.buf);
return retval;
}
EXPORT_SYMBOL_GPL(generic_rndis_bind);
static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
{
return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
}
void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
{
struct rndis_halt *halt;
/* try to clear any rndis state/activity (no i/o from stack!) */
halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
if (halt) {
halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
halt->msg_len = cpu_to_le32(sizeof *halt);
(void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
kfree(halt);
}
usbnet_cdc_unbind(dev, intf);
}
EXPORT_SYMBOL_GPL(rndis_unbind);
/*
* DATA -- host must not write zlps
*/
int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
/* This check is no longer done by usbnet */
if (skb->len < dev->net->hard_header_len)
return 0;
/* peripheral may have batched packets to us... */
while (likely(skb->len)) {
struct rndis_data_hdr *hdr = (void *)skb->data;
struct sk_buff *skb2;
u32 msg_type, msg_len, data_offset, data_len;
msg_type = le32_to_cpu(hdr->msg_type);
msg_len = le32_to_cpu(hdr->msg_len);
data_offset = le32_to_cpu(hdr->data_offset);
data_len = le32_to_cpu(hdr->data_len);
/* don't choke if we see oob, per-packet data, etc */
if (unlikely(msg_type != RNDIS_MSG_PACKET || skb->len < msg_len
|| (data_offset + data_len + 8) > msg_len)) {
dev->net->stats.rx_frame_errors++;
netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
le32_to_cpu(hdr->msg_type),
msg_len, data_offset, data_len, skb->len);
return 0;
}
skb_pull(skb, 8 + data_offset);
/* at most one packet left? */
if (likely((data_len - skb->len) <= sizeof *hdr)) {
skb_trim(skb, data_len);
break;
}
/* try to return all the packets in the batch */
skb2 = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!skb2))
break;
skb_pull(skb, msg_len - sizeof *hdr);
skb_trim(skb2, data_len);
usbnet_skb_return(dev, skb2);
}
/* caller will usbnet_skb_return the remaining packet */
return 1;
}
EXPORT_SYMBOL_GPL(rndis_rx_fixup);
struct sk_buff *
rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
struct rndis_data_hdr *hdr;
struct sk_buff *skb2;
unsigned len = skb->len;
if (likely(!skb_cloned(skb))) {
int room = skb_headroom(skb);
/* enough head room as-is? */
if (unlikely((sizeof *hdr) <= room))
goto fill;
/* enough room, but needs to be readjusted? */
room += skb_tailroom(skb);
if (likely((sizeof *hdr) <= room)) {
skb->data = memmove(skb->head + sizeof *hdr,
skb->data, len);
skb_set_tail_pointer(skb, len);
goto fill;
}
}
/* create a new skb, with the correct size (and tailpad) */
skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
dev_kfree_skb_any(skb);
if (unlikely(!skb2))
return skb2;
skb = skb2;
/* fill out the RNDIS header. we won't bother trying to batch
* packets; Linux minimizes wasted bandwidth through tx queues.
*/
fill:
hdr = __skb_push(skb, sizeof *hdr);
memset(hdr, 0, sizeof *hdr);
hdr->msg_type = cpu_to_le32(RNDIS_MSG_PACKET);
hdr->msg_len = cpu_to_le32(skb->len);
hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
hdr->data_len = cpu_to_le32(len);
/* FIXME make the last packet always be short ... */
return skb;
}
EXPORT_SYMBOL_GPL(rndis_tx_fixup);
static const struct driver_info rndis_info = {
.description = "RNDIS device",
.flags = FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
.bind = rndis_bind,
.unbind = rndis_unbind,
.status = rndis_status,
.rx_fixup = rndis_rx_fixup,
.tx_fixup = rndis_tx_fixup,
};
static const struct driver_info rndis_poll_status_info = {
.description = "RNDIS device (poll status before control)",
.flags = FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
.data = RNDIS_DRIVER_DATA_POLL_STATUS,
.bind = rndis_bind,
.unbind = rndis_unbind,
.status = rndis_status,
.rx_fixup = rndis_rx_fixup,
.tx_fixup = rndis_tx_fixup,
};
/*-------------------------------------------------------------------------*/
static const struct usb_device_id products [] = {
{
/* 2Wire HomePortal 1000SW */
USB_DEVICE_AND_INTERFACE_INFO(0x1630, 0x0042,
USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
.driver_info = (unsigned long) &rndis_poll_status_info,
}, {
/* Hytera Communications DMR radios' "Radio to PC Network" */
USB_VENDOR_AND_INTERFACE_INFO(0x238b,
USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
.driver_info = (unsigned long)&rndis_info,
}, {
/* RNDIS is MSFT's un-official variant of CDC ACM */
USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
.driver_info = (unsigned long) &rndis_info,
}, {
/* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
.driver_info = (unsigned long) &rndis_poll_status_info,
}, {
/* RNDIS for tethering */
USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
.driver_info = (unsigned long) &rndis_info,
}, {
/* Novatel Verizon USB730L */
USB_INTERFACE_INFO(USB_CLASS_MISC, 4, 1),
.driver_info = (unsigned long) &rndis_info,
},
{ }, // END
};
MODULE_DEVICE_TABLE(usb, products);
static struct usb_driver rndis_driver = {
.name = "rndis_host",
.id_table = products,
.probe = usbnet_probe,
.disconnect = usbnet_disconnect,
.suspend = usbnet_suspend,
.resume = usbnet_resume,
.disable_hub_initiated_lpm = 1,
};
module_usb_driver(rndis_driver);
MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("USB Host side RNDIS driver");
MODULE_LICENSE("GPL");
本文介绍了一种在网络中发送数据包的方法，包括skb_copy_xmit和skb_clone_xmit两个函数的具体实现细节。这些函数负责复制或克隆原始数据包，并将其发送到指定设备。
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