drivers/usb/net/rndis_host.c

   1 /*
   2  * Host Side support for RNDIS Networking Links
   3  * Copyright (C) 2005 by David Brownell
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 // #define      DEBUG                   // error path messages, extra info
  21 // #define      VERBOSE                 // more; success messages
  22
  23 #include <linux/module.h>
  24 #include <linux/init.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/etherdevice.h>
  27 #include <linux/ethtool.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/mii.h>
  30 #include <linux/usb.h>
  31 #include <linux/usb/cdc.h>
  32
  33 #include "usbnet.h"
  34
  35
  36 /*
  37  * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
  38  * course ACM was intended for modems, not Ethernet links!  USB's standard
  39  * for Ethernet links is "CDC Ethernet", which is significantly simpler.
  40  *
  41  * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
  42  * include:
  43  *    - Power management in particular relies on information that's scattered
  44  *      through other documentation, and which is incomplete or incorrect even
  45  *      there.
  46  *    - There are various undocumented protocol requirements, such as the
  47  *      need to send unused garbage in control-OUT messages.
  48  *    - In some cases, MS-Windows will emit undocumented requests; this
  49  *      matters more to peripheral implementations than host ones.
  50  *
  51  * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
  52  *
  53  * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
  54  * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
  55  * currently rare) "Ethernet Emulation Model" (EEM).
  56  */
  57
  58 /*
  59  * CONTROL uses CDC "encapsulated commands" with funky notifications.
  60  *  - control-out:  SEND_ENCAPSULATED
  61  *  - interrupt-in:  RESPONSE_AVAILABLE
  62  *  - control-in:  GET_ENCAPSULATED
  63  *
  64  * We'll try to ignore the RESPONSE_AVAILABLE notifications.
  65  *
  66  * REVISIT some RNDIS implementations seem to have curious issues still
  67  * to be resolved.
  68  */
  69 struct rndis_msg_hdr {
  70         __le32  msg_type;                       /* RNDIS_MSG_* */
  71         __le32  msg_len;
  72         // followed by data that varies between messages
  73         __le32  request_id;
  74         __le32  status;
  75         // ... and more
  76 } __attribute__ ((packed));
  77
  78 /* MS-Windows uses this strange size, but RNDIS spec says 1024 minimum */
  79 #define CONTROL_BUFFER_SIZE             1025
  80
  81 /* RNDIS defines an (absurdly huge) 10 second control timeout,
  82  * but ActiveSync seems to use a more usual 5 second timeout
  83  * (which matches the USB 2.0 spec).
  84  */
  85 #define RNDIS_CONTROL_TIMEOUT_MS        (5 * 1000)
  86
  87
  88 #define ccpu2 __constant_cpu_to_le32
  89
  90 #define RNDIS_MSG_COMPLETION    ccpu2(0x80000000)
  91
  92 /* codes for "msg_type" field of rndis messages;
  93  * only the data channel uses packet messages (maybe batched);
  94  * everything else goes on the control channel.
  95  */
  96 #define RNDIS_MSG_PACKET        ccpu2(0x00000001)       /* 1-N packets */
  97 #define RNDIS_MSG_INIT          ccpu2(0x00000002)
  98 #define RNDIS_MSG_INIT_C        (RNDIS_MSG_INIT|RNDIS_MSG_COMPLETION)
  99 #define RNDIS_MSG_HALT          ccpu2(0x00000003)
 100 #define RNDIS_MSG_QUERY         ccpu2(0x00000004)
 101 #define RNDIS_MSG_QUERY_C       (RNDIS_MSG_QUERY|RNDIS_MSG_COMPLETION)
 102 #define RNDIS_MSG_SET           ccpu2(0x00000005)
 103 #define RNDIS_MSG_SET_C         (RNDIS_MSG_SET|RNDIS_MSG_COMPLETION)
 104 #define RNDIS_MSG_RESET         ccpu2(0x00000006)
 105 #define RNDIS_MSG_RESET_C       (RNDIS_MSG_RESET|RNDIS_MSG_COMPLETION)
 106 #define RNDIS_MSG_INDICATE      ccpu2(0x00000007)
 107 #define RNDIS_MSG_KEEPALIVE     ccpu2(0x00000008)
 108 #define RNDIS_MSG_KEEPALIVE_C   (RNDIS_MSG_KEEPALIVE|RNDIS_MSG_COMPLETION)
 109
 110 /* codes for "status" field of completion messages */
 111 #define RNDIS_STATUS_SUCCESS            ccpu2(0x00000000)
 112 #define RNDIS_STATUS_FAILURE            ccpu2(0xc0000001)
 113 #define RNDIS_STATUS_INVALID_DATA       ccpu2(0xc0010015)
 114 #define RNDIS_STATUS_NOT_SUPPORTED      ccpu2(0xc00000bb)
 115 #define RNDIS_STATUS_MEDIA_CONNECT      ccpu2(0x4001000b)
 116 #define RNDIS_STATUS_MEDIA_DISCONNECT   ccpu2(0x4001000c)
 117
 118
 119 struct rndis_data_hdr {
 120         __le32  msg_type;               /* RNDIS_MSG_PACKET */
 121         __le32  msg_len;                // rndis_data_hdr + data_len + pad
 122         __le32  data_offset;            // 36 -- right after header
 123         __le32  data_len;               // ... real packet size
 124
 125         __le32  oob_data_offset;        // zero
 126         __le32  oob_data_len;           // zero
 127         __le32  num_oob;                // zero
 128         __le32  packet_data_offset;     // zero
 129
 130         __le32  packet_data_len;        // zero
 131         __le32  vc_handle;              // zero
 132         __le32  reserved;               // zero
 133 } __attribute__ ((packed));
 134
 135 struct rndis_init {             /* OUT */
 136         // header and:
 137         __le32  msg_type;                       /* RNDIS_MSG_INIT */
 138         __le32  msg_len;                        // 24
 139         __le32  request_id;
 140         __le32  major_version;                  // of rndis (1.0)
 141         __le32  minor_version;
 142         __le32  max_transfer_size;
 143 } __attribute__ ((packed));
 144
 145 struct rndis_init_c {           /* IN */
 146         // header and:
 147         __le32  msg_type;                       /* RNDIS_MSG_INIT_C */
 148         __le32  msg_len;
 149         __le32  request_id;
 150         __le32  status;
 151         __le32  major_version;                  // of rndis (1.0)
 152         __le32  minor_version;
 153         __le32  device_flags;
 154         __le32  medium;                         // zero == 802.3
 155         __le32  max_packets_per_message;
 156         __le32  max_transfer_size;
 157         __le32  packet_alignment;               // max 7; (1<<n) bytes
 158         __le32  af_list_offset;                 // zero
 159         __le32  af_list_size;                   // zero
 160 } __attribute__ ((packed));
 161
 162 struct rndis_halt {             /* OUT (no reply) */
 163         // header and:
 164         __le32  msg_type;                       /* RNDIS_MSG_HALT */
 165         __le32  msg_len;
 166         __le32  request_id;
 167 } __attribute__ ((packed));
 168
 169 struct rndis_query {            /* OUT */
 170         // header and:
 171         __le32  msg_type;                       /* RNDIS_MSG_QUERY */
 172         __le32  msg_len;
 173         __le32  request_id;
 174         __le32  oid;
 175         __le32  len;
 176         __le32  offset;
 177 /*?*/   __le32  handle;                         // zero
 178 } __attribute__ ((packed));
 179
 180 struct rndis_query_c {          /* IN */
 181         // header and:
 182         __le32  msg_type;                       /* RNDIS_MSG_QUERY_C */
 183         __le32  msg_len;
 184         __le32  request_id;
 185         __le32  status;
 186         __le32  len;
 187         __le32  offset;
 188 } __attribute__ ((packed));
 189
 190 struct rndis_set {              /* OUT */
 191         // header and:
 192         __le32  msg_type;                       /* RNDIS_MSG_SET */
 193         __le32  msg_len;
 194         __le32  request_id;
 195         __le32  oid;
 196         __le32  len;
 197         __le32  offset;
 198 /*?*/   __le32  handle;                         // zero
 199 } __attribute__ ((packed));
 200
 201 struct rndis_set_c {            /* IN */
 202         // header and:
 203         __le32  msg_type;                       /* RNDIS_MSG_SET_C */
 204         __le32  msg_len;
 205         __le32  request_id;
 206         __le32  status;
 207 } __attribute__ ((packed));
 208
 209 struct rndis_reset {            /* IN */
 210         // header and:
 211         __le32  msg_type;                       /* RNDIS_MSG_RESET */
 212         __le32  msg_len;
 213         __le32  reserved;
 214 } __attribute__ ((packed));
 215
 216 struct rndis_reset_c {          /* OUT */
 217         // header and:
 218         __le32  msg_type;                       /* RNDIS_MSG_RESET_C */
 219         __le32  msg_len;
 220         __le32  status;
 221         __le32  addressing_lost;
 222 } __attribute__ ((packed));
 223
 224 struct rndis_indicate {         /* IN (unrequested) */
 225         // header and:
 226         __le32  msg_type;                       /* RNDIS_MSG_INDICATE */
 227         __le32  msg_len;
 228         __le32  status;
 229         __le32  length;
 230         __le32  offset;
 231 /**/    __le32  diag_status;
 232         __le32  error_offset;
 233 /**/    __le32  message;
 234 } __attribute__ ((packed));
 235
 236 struct rndis_keepalive {        /* OUT (optionally IN) */
 237         // header and:
 238         __le32  msg_type;                       /* RNDIS_MSG_KEEPALIVE */
 239         __le32  msg_len;
 240         __le32  request_id;
 241 } __attribute__ ((packed));
 242
 243 struct rndis_keepalive_c {      /* IN (optionally OUT) */
 244         // header and:
 245         __le32  msg_type;                       /* RNDIS_MSG_KEEPALIVE_C */
 246         __le32  msg_len;
 247         __le32  request_id;
 248         __le32  status;
 249 } __attribute__ ((packed));
 250
 251 /* NOTE:  about 30 OIDs are "mandatory" for peripherals to support ... and
 252  * there are gobs more that may optionally be supported.  We'll avoid as much
 253  * of that mess as possible.
 254  */
 255 #define OID_802_3_PERMANENT_ADDRESS     ccpu2(0x01010101)
 256 #define OID_GEN_CURRENT_PACKET_FILTER   ccpu2(0x0001010e)
 257
 258 /*
 259  * RNDIS notifications from device: command completion; "reverse"
 260  * keepalives; etc
 261  */
 262 static void rndis_status(struct usbnet *dev, struct urb *urb)
 263 {
 264         devdbg(dev, "rndis status urb, len %d stat %d",
 265                 urb->actual_length, urb->status);
 266         // FIXME for keepalives, respond immediately (asynchronously)
 267         // if not an RNDIS status, do like cdc_status(dev,urb) does
 268 }
 269
 270 /*
 271  * RPC done RNDIS-style.  Caller guarantees:
 272  * - message is properly byteswapped
 273  * - there's no other request pending
 274  * - buf can hold up to 1KB response (required by RNDIS spec)
 275  * On return, the first few entries are already byteswapped.
 276  *
 277  * Call context is likely probe(), before interface name is known,
 278  * which is why we won't try to use it in the diagnostics.
 279  */
 280 static int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf)
 281 {
 282         struct cdc_state        *info = (void *) &dev->data;
 283         int                     master_ifnum;
 284         int                     retval;
 285         unsigned                count;
 286         __le32                  rsp;
 287         u32                     xid = 0, msg_len, request_id;
 288
 289         /* REVISIT when this gets called from contexts other than probe() or
 290          * disconnect(): either serialize, or dispatch responses on xid
 291          */
 292
 293         /* Issue the request; xid is unique, don't bother byteswapping it */
 294         if (likely(buf->msg_type != RNDIS_MSG_HALT
 295                         && buf->msg_type != RNDIS_MSG_RESET)) {
 296                 xid = dev->xid++;
 297                 if (!xid)
 298                         xid = dev->xid++;
 299                 buf->request_id = (__force __le32) xid;
 300         }
 301         master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
 302         retval = usb_control_msg(dev->udev,
 303                 usb_sndctrlpipe(dev->udev, 0),
 304                 USB_CDC_SEND_ENCAPSULATED_COMMAND,
 305                 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 306                 0, master_ifnum,
 307                 buf, le32_to_cpu(buf->msg_len),
 308                 RNDIS_CONTROL_TIMEOUT_MS);
 309         if (unlikely(retval < 0 || xid == 0))
 310                 return retval;
 311
 312         // FIXME Seems like some devices discard responses when
 313         // we time out and cancel our "get response" requests...
 314         // so, this is fragile.  Probably need to poll for status.
 315
 316         /* ignore status endpoint, just poll the control channel;
 317          * the request probably completed immediately
 318          */
 319         rsp = buf->msg_type | RNDIS_MSG_COMPLETION;
 320         for (count = 0; count < 10; count++) {
 321                 memset(buf, 0, CONTROL_BUFFER_SIZE);
 322                 retval = usb_control_msg(dev->udev,
 323                         usb_rcvctrlpipe(dev->udev, 0),
 324                         USB_CDC_GET_ENCAPSULATED_RESPONSE,
 325                         USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 326                         0, master_ifnum,
 327                         buf, CONTROL_BUFFER_SIZE,
 328                         RNDIS_CONTROL_TIMEOUT_MS);
 329                 if (likely(retval >= 8)) {
 330                         msg_len = le32_to_cpu(buf->msg_len);
 331                         request_id = (__force u32) buf->request_id;
 332                         if (likely(buf->msg_type == rsp)) {
 333                                 if (likely(request_id == xid)) {
 334                                         if (unlikely(rsp == RNDIS_MSG_RESET_C))
 335                                                 return 0;
 336                                         if (likely(RNDIS_STATUS_SUCCESS
 337                                                         == buf->status))
 338                                                 return 0;
 339                                         dev_dbg(&info->control->dev,
 340                                                 "rndis reply status %08x\n",
 341                                                 le32_to_cpu(buf->status));
 342                                         return -EL3RST;
 343                                 }
 344                                 dev_dbg(&info->control->dev,
 345                                         "rndis reply id %d expected %d\n",
 346                                         request_id, xid);
 347                                 /* then likely retry */
 348                         } else switch (buf->msg_type) {
 349                         case RNDIS_MSG_INDICATE: {      /* fault */
 350                                 // struct rndis_indicate *msg = (void *)buf;
 351                                 dev_info(&info->control->dev,
 352                                          "rndis fault indication\n");
 353                                 }
 354                                 break;
 355                         case RNDIS_MSG_KEEPALIVE: {     /* ping */
 356                                 struct rndis_keepalive_c *msg = (void *)buf;
 357
 358                                 msg->msg_type = RNDIS_MSG_KEEPALIVE_C;
 359                                 msg->msg_len = ccpu2(sizeof *msg);
 360                                 msg->status = RNDIS_STATUS_SUCCESS;
 361                                 retval = usb_control_msg(dev->udev,
 362                                         usb_sndctrlpipe(dev->udev, 0),
 363                                         USB_CDC_SEND_ENCAPSULATED_COMMAND,
 364                                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 365                                         0, master_ifnum,
 366                                         msg, sizeof *msg,
 367                                         RNDIS_CONTROL_TIMEOUT_MS);
 368                                 if (unlikely(retval < 0))
 369                                         dev_dbg(&info->control->dev,
 370                                                 "rndis keepalive err %d\n",
 371                                                 retval);
 372                                 }
 373                                 break;
 374                         default:
 375                                 dev_dbg(&info->control->dev,
 376                                         "unexpected rndis msg %08x len %d\n",
 377                                         le32_to_cpu(buf->msg_type), msg_len);
 378                         }
 379                 } else {
 380                         /* device probably issued a protocol stall; ignore */
 381                         dev_dbg(&info->control->dev,
 382                                 "rndis response error, code %d\n", retval);
 383                 }
 384                 msleep(2);
 385         }
 386         dev_dbg(&info->control->dev, "rndis response timeout\n");
 387         return -ETIMEDOUT;
 388 }
 389
 390 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
 391 {
 392         int                     retval;
 393         struct net_device       *net = dev->net;
 394         struct cdc_state        *info = (void *) &dev->data;
 395         union {
 396                 void                    *buf;
 397                 struct rndis_msg_hdr    *header;
 398                 struct rndis_init       *init;
 399                 struct rndis_init_c     *init_c;
 400                 struct rndis_query      *get;
 401                 struct rndis_query_c    *get_c;
 402                 struct rndis_set        *set;
 403                 struct rndis_set_c      *set_c;
 404         } u;
 405         u32                     tmp;
 406
 407         /* we can't rely on i/o from stack working, or stack allocation */
 408         u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
 409         if (!u.buf)
 410                 return -ENOMEM;
 411         retval = usbnet_generic_cdc_bind(dev, intf);
 412         if (retval < 0)
 413                 goto fail;
 414
 415         u.init->msg_type = RNDIS_MSG_INIT;
 416         u.init->msg_len = ccpu2(sizeof *u.init);
 417         u.init->major_version = ccpu2(1);
 418         u.init->minor_version = ccpu2(0);
 419
 420         /* max transfer (in spec) is 0x4000 at full speed, but for
 421          * TX we'll stick to one Ethernet packet plus RNDIS framing.
 422          * For RX we handle drivers that zero-pad to end-of-packet.
 423          * Don't let userspace change these settings.
 424          */
 425         net->hard_header_len += sizeof (struct rndis_data_hdr);
 426         dev->hard_mtu = net->mtu + net->hard_header_len;
 427
 428         dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
 429         dev->rx_urb_size &= ~(dev->maxpacket - 1);
 430         u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
 431
 432         net->change_mtu = NULL;
 433         retval = rndis_command(dev, u.header);
 434         if (unlikely(retval < 0)) {
 435                 /* it might not even be an RNDIS device!! */
 436                 dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
 437                 goto fail_and_release;
 438         }
 439         tmp = le32_to_cpu(u.init_c->max_transfer_size);
 440         if (tmp < dev->hard_mtu) {
 441                 dev_err(&intf->dev,
 442                         "dev can't take %u byte packets (max %u)\n",
 443                         dev->hard_mtu, tmp);
 444                 goto fail_and_release;
 445         }
 446
 447         /* REVISIT:  peripheral "alignment" request is ignored ... */
 448         dev_dbg(&intf->dev,
 449                 "hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
 450                 dev->hard_mtu, tmp, dev->rx_urb_size,
 451                 1 << le32_to_cpu(u.init_c->packet_alignment));
 452
 453         /* Get designated host ethernet address.
 454          *
 455          * Adding a payload exactly the same size as the expected response
 456          * payload is an evident requirement MSFT added for ActiveSync.
 457          * This undocumented (and nonsensical) issue was found by sniffing
 458          * protocol requests from the ActiveSync 4.1 Windows driver.
 459          */
 460         memset(u.get, 0, sizeof *u.get + 48);
 461         u.get->msg_type = RNDIS_MSG_QUERY;
 462         u.get->msg_len = ccpu2(sizeof *u.get + 48);
 463         u.get->oid = OID_802_3_PERMANENT_ADDRESS;
 464         u.get->len = ccpu2(48);
 465         u.get->offset = ccpu2(20);
 466
 467         retval = rndis_command(dev, u.header);
 468         if (unlikely(retval < 0)) {
 469                 dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
 470                 goto fail_and_release;
 471         }
 472         tmp = le32_to_cpu(u.get_c->offset);
 473         if (unlikely((tmp + 8) > (CONTROL_BUFFER_SIZE - ETH_ALEN)
 474                         || u.get_c->len != ccpu2(ETH_ALEN))) {
 475                 dev_err(&intf->dev, "rndis ethaddr off %d len %d ?\n",
 476                         tmp, le32_to_cpu(u.get_c->len));
 477                 retval = -EDOM;
 478                 goto fail_and_release;
 479         }
 480         memcpy(net->dev_addr, tmp + (char *)&u.get_c->request_id, ETH_ALEN);
 481
 482         /* set a nonzero filter to enable data transfers */
 483         memset(u.set, 0, sizeof *u.set);
 484         u.set->msg_type = RNDIS_MSG_SET;
 485         u.set->msg_len = ccpu2(4 + sizeof *u.set);
 486         u.set->oid = OID_GEN_CURRENT_PACKET_FILTER;
 487         u.set->len = ccpu2(4);
 488         u.set->offset = ccpu2((sizeof *u.set) - 8);
 489         *(__le32 *)(u.buf + sizeof *u.set) = ccpu2(DEFAULT_FILTER);
 490
 491         retval = rndis_command(dev, u.header);
 492         if (unlikely(retval < 0)) {
 493                 dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
 494                 goto fail_and_release;
 495         }
 496
 497         retval = 0;
 498
 499         kfree(u.buf);
 500         return retval;
 501
 502 fail_and_release:
 503         usb_set_intfdata(info->data, NULL);
 504         usb_driver_release_interface(driver_of(intf), info->data);
 505 fail:
 506         kfree(u.buf);
 507         return retval;
 508 }
 509
 510 static void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
 511 {
 512         struct rndis_halt       *halt;
 513
 514         /* try to clear any rndis state/activity (no i/o from stack!) */
 515         halt = kzalloc(sizeof *halt, GFP_KERNEL);
 516         if (halt) {
 517                 halt->msg_type = RNDIS_MSG_HALT;
 518                 halt->msg_len = ccpu2(sizeof *halt);
 519                 (void) rndis_command(dev, (void *)halt);
 520                 kfree(halt);
 521         }
 522
 523         return usbnet_cdc_unbind(dev, intf);
 524 }
 525
 526 /*
 527  * DATA -- host must not write zlps
 528  */
 529 static int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 530 {
 531         /* peripheral may have batched packets to us... */
 532         while (likely(skb->len)) {
 533                 struct rndis_data_hdr   *hdr = (void *)skb->data;
 534                 struct sk_buff          *skb2;
 535                 u32                     msg_len, data_offset, data_len;
 536
 537                 msg_len = le32_to_cpu(hdr->msg_len);
 538                 data_offset = le32_to_cpu(hdr->data_offset);
 539                 data_len = le32_to_cpu(hdr->data_len);
 540
 541                 /* don't choke if we see oob, per-packet data, etc */
 542                 if (unlikely(hdr->msg_type != RNDIS_MSG_PACKET
 543                                 || skb->len < msg_len
 544                                 || (data_offset + data_len + 8) > msg_len)) {
 545                         dev->stats.rx_frame_errors++;
 546                         devdbg(dev, "bad rndis message %d/%d/%d/%d, len %d",
 547                                 le32_to_cpu(hdr->msg_type),
 548                                 msg_len, data_offset, data_len, skb->len);
 549                         return 0;
 550                 }
 551                 skb_pull(skb, 8 + data_offset);
 552
 553                 /* at most one packet left? */
 554                 if (likely((data_len - skb->len) <= sizeof *hdr)) {
 555                         skb_trim(skb, data_len);
 556                         break;
 557                 }
 558
 559                 /* try to return all the packets in the batch */
 560                 skb2 = skb_clone(skb, GFP_ATOMIC);
 561                 if (unlikely(!skb2))
 562                         break;
 563                 skb_pull(skb, msg_len - sizeof *hdr);
 564                 skb_trim(skb2, data_len);
 565                 usbnet_skb_return(dev, skb2);
 566         }
 567
 568         /* caller will usbnet_skb_return the remaining packet */
 569         return 1;
 570 }
 571
 572 static struct sk_buff *
 573 rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 574 {
 575         struct rndis_data_hdr   *hdr;
 576         struct sk_buff          *skb2;
 577         unsigned                len = skb->len;
 578
 579         if (likely(!skb_cloned(skb))) {
 580                 int     room = skb_headroom(skb);
 581
 582                 /* enough head room as-is? */
 583                 if (unlikely((sizeof *hdr) <= room))
 584                         goto fill;
 585
 586                 /* enough room, but needs to be readjusted? */
 587                 room += skb_tailroom(skb);
 588                 if (likely((sizeof *hdr) <= room)) {
 589                         skb->data = memmove(skb->head + sizeof *hdr,
 590                                             skb->data, len);
 591                         skb->tail = skb->data + len;
 592                         goto fill;
 593                 }
 594         }
 595
 596         /* create a new skb, with the correct size (and tailpad) */
 597         skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
 598         dev_kfree_skb_any(skb);
 599         if (unlikely(!skb2))
 600                 return skb2;
 601         skb = skb2;
 602
 603         /* fill out the RNDIS header.  we won't bother trying to batch
 604          * packets; Linux minimizes wasted bandwidth through tx queues.
 605          */
 606 fill:
 607         hdr = (void *) __skb_push(skb, sizeof *hdr);
 608         memset(hdr, 0, sizeof *hdr);
 609         hdr->msg_type = RNDIS_MSG_PACKET;
 610         hdr->msg_len = cpu_to_le32(skb->len);
 611         hdr->data_offset = ccpu2(sizeof(*hdr) - 8);
 612         hdr->data_len = cpu_to_le32(len);
 613
 614         /* FIXME make the last packet always be short ... */
 615         return skb;
 616 }
 617
 618
 619 static const struct driver_info rndis_info = {
 620         .description =  "RNDIS device",
 621         .flags =        FLAG_ETHER | FLAG_FRAMING_RN,
 622         .bind =         rndis_bind,
 623         .unbind =       rndis_unbind,
 624         .status =       rndis_status,
 625         .rx_fixup =     rndis_rx_fixup,
 626         .tx_fixup =     rndis_tx_fixup,
 627 };
 628
 629 #undef ccpu2
 630
 631
 632 /*-------------------------------------------------------------------------*/
 633
 634 static const struct usb_device_id       products [] = {
 635 {
 636         /* RNDIS is MSFT's un-official variant of CDC ACM */
 637         USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
 638         .driver_info = (unsigned long) &rndis_info,
 639 }, {
 640         /* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
 641         USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
 642         .driver_info = (unsigned long) &rndis_info,
 643 },
 644         { },            // END
 645 };
 646 MODULE_DEVICE_TABLE(usb, products);
 647
 648 static struct usb_driver rndis_driver = {
 649         .name =         "rndis_host",
 650         .id_table =     products,
 651         .probe =        usbnet_probe,
 652         .disconnect =   usbnet_disconnect,
 653         .suspend =      usbnet_suspend,
 654         .resume =       usbnet_resume,
 655 };
 656
 657 static int __init rndis_init(void)
 658 {
 659         return usb_register(&rndis_driver);
 660 }
 661 module_init(rndis_init);
 662
 663 static void __exit rndis_exit(void)
 664 {
 665         usb_deregister(&rndis_driver);
 666 }
 667 module_exit(rndis_exit);
 668
 669 MODULE_AUTHOR("David Brownell");
 670 MODULE_DESCRIPTION("USB Host side RNDIS driver");
 671 MODULE_LICENSE("GPL");