1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * f_rndis.c -- RNDIS link function driver
4  *
5  * Copyright (C) 2003-2005,2008 David Brownell
6  * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
7  * Copyright (C) 2008 Nokia Corporation
8  * Copyright (C) 2009 Samsung Electronics
9  *                    Author: Michal Nazarewicz (mina86@mina86.com)
10  */
11 
12 /* #define VERBOSE_DEBUG */
13 
14 #include <linux/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/device.h>
18 #include <linux/etherdevice.h>
19 
20 #include <linux/atomic.h>
21 
22 #include "u_ether.h"
23 #include "u_ether_configfs.h"
24 #include "u_rndis.h"
25 #include "rndis.h"
26 #include "configfs.h"
27 
28 /*
29  * This function is an RNDIS Ethernet port -- a Microsoft protocol that's
30  * been promoted instead of the standard CDC Ethernet.  The published RNDIS
31  * spec is ambiguous, incomplete, and needlessly complex.  Variants such as
32  * ActiveSync have even worse status in terms of specification.
33  *
34  * In short:  it's a protocol controlled by (and for) Microsoft, not for an
35  * Open ecosystem or markets.  Linux supports it *only* because Microsoft
36  * doesn't support the CDC Ethernet standard.
37  *
38  * The RNDIS data transfer model is complex, with multiple Ethernet packets
39  * per USB message, and out of band data.  The control model is built around
40  * what's essentially an "RNDIS RPC" protocol.  It's all wrapped in a CDC ACM
41  * (modem, not Ethernet) veneer, with those ACM descriptors being entirely
42  * useless (they're ignored).  RNDIS expects to be the only function in its
43  * configuration, so it's no real help if you need composite devices; and
44  * it expects to be the first configuration too.
45  *
46  * There is a single technical advantage of RNDIS over CDC Ethernet, if you
47  * discount the fluff that its RPC can be made to deliver: it doesn't need
48  * a NOP altsetting for the data interface.  That lets it work on some of the
49  * "so smart it's stupid" hardware which takes over configuration changes
50  * from the software, and adds restrictions like "no altsettings".
51  *
52  * Unfortunately MSFT's RNDIS drivers are buggy.  They hang or oops, and
53  * have all sorts of contrary-to-specification oddities that can prevent
54  * them from working sanely.  Since bugfixes (or accurate specs, letting
55  * Linux work around those bugs) are unlikely to ever come from MSFT, you
56  * may want to avoid using RNDIS on purely operational grounds.
57  *
58  * Omissions from the RNDIS 1.0 specification include:
59  *
60  *   - Power management ... references data that's scattered around lots
61  *     of other documentation, which is incorrect/incomplete there too.
62  *
63  *   - There are various undocumented protocol requirements, like the need
64  *     to send garbage in some control-OUT messages.
65  *
66  *   - MS-Windows drivers sometimes emit undocumented requests.
67  */
68 
69 struct f_rndis {
70 	struct gether			port;
71 	u8				ctrl_id, data_id;
72 	u8				ethaddr[ETH_ALEN];
73 	u32				vendorID;
74 	const char			*manufacturer;
75 	struct rndis_params		*params;
76 
77 	struct usb_ep			*notify;
78 	struct usb_request		*notify_req;
79 	atomic_t			notify_count;
80 };
81 
82 static inline struct f_rndis *func_to_rndis(struct usb_function *f)
83 {
84 	return container_of(f, struct f_rndis, port.func);
85 }
86 
87 /* peak (theoretical) bulk transfer rate in bits-per-second */
88 static unsigned int bitrate(struct usb_gadget *g)
89 {
90 	if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER)
91 		return 13 * 1024 * 8 * 1000 * 8;
92 	else if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
93 		return 13 * 512 * 8 * 1000 * 8;
94 	else
95 		return 19 * 64 * 1 * 1000 * 8;
96 }
97 
98 /*-------------------------------------------------------------------------*/
99 
100 /*
101  */
102 
103 #define RNDIS_STATUS_INTERVAL_MS	32
104 #define STATUS_BYTECOUNT		8	/* 8 bytes data */
105 
106 
107 /* interface descriptor: */
108 
109 static struct usb_interface_descriptor rndis_control_intf = {
110 	.bLength =		sizeof rndis_control_intf,
111 	.bDescriptorType =	USB_DT_INTERFACE,
112 
113 	/* .bInterfaceNumber = DYNAMIC */
114 	/* status endpoint is optional; this could be patched later */
115 	.bNumEndpoints =	1,
116 	.bInterfaceClass =	USB_CLASS_COMM,
117 	.bInterfaceSubClass =   USB_CDC_SUBCLASS_ACM,
118 	.bInterfaceProtocol =   USB_CDC_ACM_PROTO_VENDOR,
119 	/* .iInterface = DYNAMIC */
120 };
121 
122 static struct usb_cdc_header_desc header_desc = {
123 	.bLength =		sizeof header_desc,
124 	.bDescriptorType =	USB_DT_CS_INTERFACE,
125 	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
126 
127 	.bcdCDC =		cpu_to_le16(0x0110),
128 };
129 
130 static struct usb_cdc_call_mgmt_descriptor call_mgmt_descriptor = {
131 	.bLength =		sizeof call_mgmt_descriptor,
132 	.bDescriptorType =	USB_DT_CS_INTERFACE,
133 	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
134 
135 	.bmCapabilities =	0x00,
136 	.bDataInterface =	0x01,
137 };
138 
139 static struct usb_cdc_acm_descriptor rndis_acm_descriptor = {
140 	.bLength =		sizeof rndis_acm_descriptor,
141 	.bDescriptorType =	USB_DT_CS_INTERFACE,
142 	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
143 
144 	.bmCapabilities =	0x00,
145 };
146 
147 static struct usb_cdc_union_desc rndis_union_desc = {
148 	.bLength =		sizeof(rndis_union_desc),
149 	.bDescriptorType =	USB_DT_CS_INTERFACE,
150 	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
151 	/* .bMasterInterface0 =	DYNAMIC */
152 	/* .bSlaveInterface0 =	DYNAMIC */
153 };
154 
155 /* the data interface has two bulk endpoints */
156 
157 static struct usb_interface_descriptor rndis_data_intf = {
158 	.bLength =		sizeof rndis_data_intf,
159 	.bDescriptorType =	USB_DT_INTERFACE,
160 
161 	/* .bInterfaceNumber = DYNAMIC */
162 	.bNumEndpoints =	2,
163 	.bInterfaceClass =	USB_CLASS_CDC_DATA,
164 	.bInterfaceSubClass =	0,
165 	.bInterfaceProtocol =	0,
166 	/* .iInterface = DYNAMIC */
167 };
168 
169 
170 static struct usb_interface_assoc_descriptor
171 rndis_iad_descriptor = {
172 	.bLength =		sizeof rndis_iad_descriptor,
173 	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
174 
175 	.bFirstInterface =	0, /* XXX, hardcoded */
176 	.bInterfaceCount = 	2,	// control + data
177 	.bFunctionClass =	USB_CLASS_COMM,
178 	.bFunctionSubClass =	USB_CDC_SUBCLASS_ETHERNET,
179 	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
180 	/* .iFunction = DYNAMIC */
181 };
182 
183 /* full speed support: */
184 
185 static struct usb_endpoint_descriptor fs_notify_desc = {
186 	.bLength =		USB_DT_ENDPOINT_SIZE,
187 	.bDescriptorType =	USB_DT_ENDPOINT,
188 
189 	.bEndpointAddress =	USB_DIR_IN,
190 	.bmAttributes =		USB_ENDPOINT_XFER_INT,
191 	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
192 	.bInterval =		RNDIS_STATUS_INTERVAL_MS,
193 };
194 
195 static struct usb_endpoint_descriptor fs_in_desc = {
196 	.bLength =		USB_DT_ENDPOINT_SIZE,
197 	.bDescriptorType =	USB_DT_ENDPOINT,
198 
199 	.bEndpointAddress =	USB_DIR_IN,
200 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
201 };
202 
203 static struct usb_endpoint_descriptor fs_out_desc = {
204 	.bLength =		USB_DT_ENDPOINT_SIZE,
205 	.bDescriptorType =	USB_DT_ENDPOINT,
206 
207 	.bEndpointAddress =	USB_DIR_OUT,
208 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
209 };
210 
211 static struct usb_descriptor_header *eth_fs_function[] = {
212 	(struct usb_descriptor_header *) &rndis_iad_descriptor,
213 
214 	/* control interface matches ACM, not Ethernet */
215 	(struct usb_descriptor_header *) &rndis_control_intf,
216 	(struct usb_descriptor_header *) &header_desc,
217 	(struct usb_descriptor_header *) &call_mgmt_descriptor,
218 	(struct usb_descriptor_header *) &rndis_acm_descriptor,
219 	(struct usb_descriptor_header *) &rndis_union_desc,
220 	(struct usb_descriptor_header *) &fs_notify_desc,
221 
222 	/* data interface has no altsetting */
223 	(struct usb_descriptor_header *) &rndis_data_intf,
224 	(struct usb_descriptor_header *) &fs_in_desc,
225 	(struct usb_descriptor_header *) &fs_out_desc,
226 	NULL,
227 };
228 
229 /* high speed support: */
230 
231 static struct usb_endpoint_descriptor hs_notify_desc = {
232 	.bLength =		USB_DT_ENDPOINT_SIZE,
233 	.bDescriptorType =	USB_DT_ENDPOINT,
234 
235 	.bEndpointAddress =	USB_DIR_IN,
236 	.bmAttributes =		USB_ENDPOINT_XFER_INT,
237 	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
238 	.bInterval =		USB_MS_TO_HS_INTERVAL(RNDIS_STATUS_INTERVAL_MS)
239 };
240 
241 static struct usb_endpoint_descriptor hs_in_desc = {
242 	.bLength =		USB_DT_ENDPOINT_SIZE,
243 	.bDescriptorType =	USB_DT_ENDPOINT,
244 
245 	.bEndpointAddress =	USB_DIR_IN,
246 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
247 	.wMaxPacketSize =	cpu_to_le16(512),
248 };
249 
250 static struct usb_endpoint_descriptor hs_out_desc = {
251 	.bLength =		USB_DT_ENDPOINT_SIZE,
252 	.bDescriptorType =	USB_DT_ENDPOINT,
253 
254 	.bEndpointAddress =	USB_DIR_OUT,
255 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
256 	.wMaxPacketSize =	cpu_to_le16(512),
257 };
258 
259 static struct usb_descriptor_header *eth_hs_function[] = {
260 	(struct usb_descriptor_header *) &rndis_iad_descriptor,
261 
262 	/* control interface matches ACM, not Ethernet */
263 	(struct usb_descriptor_header *) &rndis_control_intf,
264 	(struct usb_descriptor_header *) &header_desc,
265 	(struct usb_descriptor_header *) &call_mgmt_descriptor,
266 	(struct usb_descriptor_header *) &rndis_acm_descriptor,
267 	(struct usb_descriptor_header *) &rndis_union_desc,
268 	(struct usb_descriptor_header *) &hs_notify_desc,
269 
270 	/* data interface has no altsetting */
271 	(struct usb_descriptor_header *) &rndis_data_intf,
272 	(struct usb_descriptor_header *) &hs_in_desc,
273 	(struct usb_descriptor_header *) &hs_out_desc,
274 	NULL,
275 };
276 
277 /* super speed support: */
278 
279 static struct usb_endpoint_descriptor ss_notify_desc = {
280 	.bLength =		USB_DT_ENDPOINT_SIZE,
281 	.bDescriptorType =	USB_DT_ENDPOINT,
282 
283 	.bEndpointAddress =	USB_DIR_IN,
284 	.bmAttributes =		USB_ENDPOINT_XFER_INT,
285 	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
286 	.bInterval =		USB_MS_TO_HS_INTERVAL(RNDIS_STATUS_INTERVAL_MS)
287 };
288 
289 static struct usb_ss_ep_comp_descriptor ss_intr_comp_desc = {
290 	.bLength =		sizeof ss_intr_comp_desc,
291 	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
292 
293 	/* the following 3 values can be tweaked if necessary */
294 	/* .bMaxBurst =		0, */
295 	/* .bmAttributes =	0, */
296 	.wBytesPerInterval =	cpu_to_le16(STATUS_BYTECOUNT),
297 };
298 
299 static struct usb_endpoint_descriptor ss_in_desc = {
300 	.bLength =		USB_DT_ENDPOINT_SIZE,
301 	.bDescriptorType =	USB_DT_ENDPOINT,
302 
303 	.bEndpointAddress =	USB_DIR_IN,
304 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
305 	.wMaxPacketSize =	cpu_to_le16(1024),
306 };
307 
308 static struct usb_endpoint_descriptor ss_out_desc = {
309 	.bLength =		USB_DT_ENDPOINT_SIZE,
310 	.bDescriptorType =	USB_DT_ENDPOINT,
311 
312 	.bEndpointAddress =	USB_DIR_OUT,
313 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
314 	.wMaxPacketSize =	cpu_to_le16(1024),
315 };
316 
317 static struct usb_ss_ep_comp_descriptor ss_bulk_comp_desc = {
318 	.bLength =		sizeof ss_bulk_comp_desc,
319 	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
320 
321 	/* the following 2 values can be tweaked if necessary */
322 	/* .bMaxBurst =		0, */
323 	/* .bmAttributes =	0, */
324 };
325 
326 static struct usb_descriptor_header *eth_ss_function[] = {
327 	(struct usb_descriptor_header *) &rndis_iad_descriptor,
328 
329 	/* control interface matches ACM, not Ethernet */
330 	(struct usb_descriptor_header *) &rndis_control_intf,
331 	(struct usb_descriptor_header *) &header_desc,
332 	(struct usb_descriptor_header *) &call_mgmt_descriptor,
333 	(struct usb_descriptor_header *) &rndis_acm_descriptor,
334 	(struct usb_descriptor_header *) &rndis_union_desc,
335 	(struct usb_descriptor_header *) &ss_notify_desc,
336 	(struct usb_descriptor_header *) &ss_intr_comp_desc,
337 
338 	/* data interface has no altsetting */
339 	(struct usb_descriptor_header *) &rndis_data_intf,
340 	(struct usb_descriptor_header *) &ss_in_desc,
341 	(struct usb_descriptor_header *) &ss_bulk_comp_desc,
342 	(struct usb_descriptor_header *) &ss_out_desc,
343 	(struct usb_descriptor_header *) &ss_bulk_comp_desc,
344 	NULL,
345 };
346 
347 /* string descriptors: */
348 
349 static struct usb_string rndis_string_defs[] = {
350 	[0].s = "RNDIS Communications Control",
351 	[1].s = "RNDIS Ethernet Data",
352 	[2].s = "RNDIS",
353 	{  } /* end of list */
354 };
355 
356 static struct usb_gadget_strings rndis_string_table = {
357 	.language =		0x0409,	/* en-us */
358 	.strings =		rndis_string_defs,
359 };
360 
361 static struct usb_gadget_strings *rndis_strings[] = {
362 	&rndis_string_table,
363 	NULL,
364 };
365 
366 /*-------------------------------------------------------------------------*/
367 
368 static struct sk_buff *rndis_add_header(struct gether *port,
369 					struct sk_buff *skb)
370 {
371 	struct sk_buff *skb2;
372 
373 	if (!skb)
374 		return NULL;
375 
376 	skb2 = skb_realloc_headroom(skb, sizeof(struct rndis_packet_msg_type));
377 	rndis_add_hdr(skb2);
378 
379 	dev_kfree_skb(skb);
380 	return skb2;
381 }
382 
383 static void rndis_response_available(void *_rndis)
384 {
385 	struct f_rndis			*rndis = _rndis;
386 	struct usb_request		*req = rndis->notify_req;
387 	struct usb_composite_dev	*cdev = rndis->port.func.config->cdev;
388 	__le32				*data = req->buf;
389 	int				status;
390 
391 	if (atomic_inc_return(&rndis->notify_count) != 1)
392 		return;
393 
394 	/* Send RNDIS RESPONSE_AVAILABLE notification; a
395 	 * USB_CDC_NOTIFY_RESPONSE_AVAILABLE "should" work too
396 	 *
397 	 * This is the only notification defined by RNDIS.
398 	 */
399 	data[0] = cpu_to_le32(1);
400 	data[1] = cpu_to_le32(0);
401 
402 	status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
403 	if (status) {
404 		atomic_dec(&rndis->notify_count);
405 		DBG(cdev, "notify/0 --> %d\n", status);
406 	}
407 }
408 
409 static void rndis_response_complete(struct usb_ep *ep, struct usb_request *req)
410 {
411 	struct f_rndis			*rndis = req->context;
412 	struct usb_composite_dev	*cdev = rndis->port.func.config->cdev;
413 	int				status = req->status;
414 
415 	/* after TX:
416 	 *  - USB_CDC_GET_ENCAPSULATED_RESPONSE (ep0/control)
417 	 *  - RNDIS_RESPONSE_AVAILABLE (status/irq)
418 	 */
419 	switch (status) {
420 	case -ECONNRESET:
421 	case -ESHUTDOWN:
422 		/* connection gone */
423 		atomic_set(&rndis->notify_count, 0);
424 		break;
425 	default:
426 		DBG(cdev, "RNDIS %s response error %d, %d/%d\n",
427 			ep->name, status,
428 			req->actual, req->length);
429 		/* FALLTHROUGH */
430 	case 0:
431 		if (ep != rndis->notify)
432 			break;
433 
434 		/* handle multiple pending RNDIS_RESPONSE_AVAILABLE
435 		 * notifications by resending until we're done
436 		 */
437 		if (atomic_dec_and_test(&rndis->notify_count))
438 			break;
439 		status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
440 		if (status) {
441 			atomic_dec(&rndis->notify_count);
442 			DBG(cdev, "notify/1 --> %d\n", status);
443 		}
444 		break;
445 	}
446 }
447 
448 static void rndis_command_complete(struct usb_ep *ep, struct usb_request *req)
449 {
450 	struct f_rndis			*rndis = req->context;
451 	int				status;
452 
453 	/* received RNDIS command from USB_CDC_SEND_ENCAPSULATED_COMMAND */
454 //	spin_lock(&dev->lock);
455 	status = rndis_msg_parser(rndis->params, (u8 *) req->buf);
456 	if (status < 0)
457 		pr_err("RNDIS command error %d, %d/%d\n",
458 			status, req->actual, req->length);
459 //	spin_unlock(&dev->lock);
460 }
461 
462 static int
463 rndis_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
464 {
465 	struct f_rndis		*rndis = func_to_rndis(f);
466 	struct usb_composite_dev *cdev = f->config->cdev;
467 	struct usb_request	*req = cdev->req;
468 	int			value = -EOPNOTSUPP;
469 	u16			w_index = le16_to_cpu(ctrl->wIndex);
470 	u16			w_value = le16_to_cpu(ctrl->wValue);
471 	u16			w_length = le16_to_cpu(ctrl->wLength);
472 
473 	/* composite driver infrastructure handles everything except
474 	 * CDC class messages; interface activation uses set_alt().
475 	 */
476 	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
477 
478 	/* RNDIS uses the CDC command encapsulation mechanism to implement
479 	 * an RPC scheme, with much getting/setting of attributes by OID.
480 	 */
481 	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
482 			| USB_CDC_SEND_ENCAPSULATED_COMMAND:
483 		if (w_value || w_index != rndis->ctrl_id)
484 			goto invalid;
485 		/* read the request; process it later */
486 		value = w_length;
487 		req->complete = rndis_command_complete;
488 		req->context = rndis;
489 		/* later, rndis_response_available() sends a notification */
490 		break;
491 
492 	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
493 			| USB_CDC_GET_ENCAPSULATED_RESPONSE:
494 		if (w_value || w_index != rndis->ctrl_id)
495 			goto invalid;
496 		else {
497 			u8 *buf;
498 			u32 n;
499 
500 			/* return the result */
501 			buf = rndis_get_next_response(rndis->params, &n);
502 			if (buf) {
503 				memcpy(req->buf, buf, n);
504 				req->complete = rndis_response_complete;
505 				req->context = rndis;
506 				rndis_free_response(rndis->params, buf);
507 				value = n;
508 			}
509 			/* else stalls ... spec says to avoid that */
510 		}
511 		break;
512 
513 	default:
514 invalid:
515 		VDBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
516 			ctrl->bRequestType, ctrl->bRequest,
517 			w_value, w_index, w_length);
518 	}
519 
520 	/* respond with data transfer or status phase? */
521 	if (value >= 0) {
522 		DBG(cdev, "rndis req%02x.%02x v%04x i%04x l%d\n",
523 			ctrl->bRequestType, ctrl->bRequest,
524 			w_value, w_index, w_length);
525 		req->zero = (value < w_length);
526 		req->length = value;
527 		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
528 		if (value < 0)
529 			ERROR(cdev, "rndis response on err %d\n", value);
530 	}
531 
532 	/* device either stalls (value < 0) or reports success */
533 	return value;
534 }
535 
536 
537 static int rndis_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
538 {
539 	struct f_rndis		*rndis = func_to_rndis(f);
540 	struct usb_composite_dev *cdev = f->config->cdev;
541 
542 	/* we know alt == 0 */
543 
544 	if (intf == rndis->ctrl_id) {
545 		VDBG(cdev, "reset rndis control %d\n", intf);
546 		usb_ep_disable(rndis->notify);
547 
548 		if (!rndis->notify->desc) {
549 			VDBG(cdev, "init rndis ctrl %d\n", intf);
550 			if (config_ep_by_speed(cdev->gadget, f, rndis->notify))
551 				goto fail;
552 		}
553 		usb_ep_enable(rndis->notify);
554 
555 	} else if (intf == rndis->data_id) {
556 		struct net_device	*net;
557 
558 		if (rndis->port.in_ep->enabled) {
559 			DBG(cdev, "reset rndis\n");
560 			gether_disconnect(&rndis->port);
561 		}
562 
563 		if (!rndis->port.in_ep->desc || !rndis->port.out_ep->desc) {
564 			DBG(cdev, "init rndis\n");
565 			if (config_ep_by_speed(cdev->gadget, f,
566 					       rndis->port.in_ep) ||
567 			    config_ep_by_speed(cdev->gadget, f,
568 					       rndis->port.out_ep)) {
569 				rndis->port.in_ep->desc = NULL;
570 				rndis->port.out_ep->desc = NULL;
571 				goto fail;
572 			}
573 		}
574 
575 		/* Avoid ZLPs; they can be troublesome. */
576 		rndis->port.is_zlp_ok = false;
577 
578 		/* RNDIS should be in the "RNDIS uninitialized" state,
579 		 * either never activated or after rndis_uninit().
580 		 *
581 		 * We don't want data to flow here until a nonzero packet
582 		 * filter is set, at which point it enters "RNDIS data
583 		 * initialized" state ... but we do want the endpoints
584 		 * to be activated.  It's a strange little state.
585 		 *
586 		 * REVISIT the RNDIS gadget code has done this wrong for a
587 		 * very long time.  We need another call to the link layer
588 		 * code -- gether_updown(...bool) maybe -- to do it right.
589 		 */
590 		rndis->port.cdc_filter = 0;
591 
592 		DBG(cdev, "RNDIS RX/TX early activation ... \n");
593 		net = gether_connect(&rndis->port);
594 		if (IS_ERR(net))
595 			return PTR_ERR(net);
596 
597 		rndis_set_param_dev(rndis->params, net,
598 				&rndis->port.cdc_filter);
599 	} else
600 		goto fail;
601 
602 	return 0;
603 fail:
604 	return -EINVAL;
605 }
606 
607 static void rndis_disable(struct usb_function *f)
608 {
609 	struct f_rndis		*rndis = func_to_rndis(f);
610 	struct usb_composite_dev *cdev = f->config->cdev;
611 
612 	if (!rndis->notify->enabled)
613 		return;
614 
615 	DBG(cdev, "rndis deactivated\n");
616 
617 	rndis_uninit(rndis->params);
618 	gether_disconnect(&rndis->port);
619 
620 	usb_ep_disable(rndis->notify);
621 }
622 
623 /*-------------------------------------------------------------------------*/
624 
625 /*
626  * This isn't quite the same mechanism as CDC Ethernet, since the
627  * notification scheme passes less data, but the same set of link
628  * states must be tested.  A key difference is that altsettings are
629  * not used to tell whether the link should send packets or not.
630  */
631 
632 static void rndis_open(struct gether *geth)
633 {
634 	struct f_rndis		*rndis = func_to_rndis(&geth->func);
635 	struct usb_composite_dev *cdev = geth->func.config->cdev;
636 
637 	DBG(cdev, "%s\n", __func__);
638 
639 	rndis_set_param_medium(rndis->params, RNDIS_MEDIUM_802_3,
640 				bitrate(cdev->gadget) / 100);
641 	rndis_signal_connect(rndis->params);
642 }
643 
644 static void rndis_close(struct gether *geth)
645 {
646 	struct f_rndis		*rndis = func_to_rndis(&geth->func);
647 
648 	DBG(geth->func.config->cdev, "%s\n", __func__);
649 
650 	rndis_set_param_medium(rndis->params, RNDIS_MEDIUM_802_3, 0);
651 	rndis_signal_disconnect(rndis->params);
652 }
653 
654 /*-------------------------------------------------------------------------*/
655 
656 /* Some controllers can't support RNDIS ... */
657 static inline bool can_support_rndis(struct usb_configuration *c)
658 {
659 	/* everything else is *presumably* fine */
660 	return true;
661 }
662 
663 /* ethernet function driver setup/binding */
664 
665 static int
666 rndis_bind(struct usb_configuration *c, struct usb_function *f)
667 {
668 	struct usb_composite_dev *cdev = c->cdev;
669 	struct f_rndis		*rndis = func_to_rndis(f);
670 	struct usb_string	*us;
671 	int			status;
672 	struct usb_ep		*ep;
673 
674 	struct f_rndis_opts *rndis_opts;
675 
676 	if (!can_support_rndis(c))
677 		return -EINVAL;
678 
679 	rndis_opts = container_of(f->fi, struct f_rndis_opts, func_inst);
680 
681 	if (cdev->use_os_string) {
682 		f->os_desc_table = kzalloc(sizeof(*f->os_desc_table),
683 					   GFP_KERNEL);
684 		if (!f->os_desc_table)
685 			return -ENOMEM;
686 		f->os_desc_n = 1;
687 		f->os_desc_table[0].os_desc = &rndis_opts->rndis_os_desc;
688 	}
689 
690 	rndis_iad_descriptor.bFunctionClass = rndis_opts->class;
691 	rndis_iad_descriptor.bFunctionSubClass = rndis_opts->subclass;
692 	rndis_iad_descriptor.bFunctionProtocol = rndis_opts->protocol;
693 
694 	/*
695 	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
696 	 * configurations are bound in sequence with list_for_each_entry,
697 	 * in each configuration its functions are bound in sequence
698 	 * with list_for_each_entry, so we assume no race condition
699 	 * with regard to rndis_opts->bound access
700 	 */
701 	if (!rndis_opts->bound) {
702 		gether_set_gadget(rndis_opts->net, cdev->gadget);
703 		status = gether_register_netdev(rndis_opts->net);
704 		if (status)
705 			goto fail;
706 		rndis_opts->bound = true;
707 	}
708 
709 	us = usb_gstrings_attach(cdev, rndis_strings,
710 				 ARRAY_SIZE(rndis_string_defs));
711 	if (IS_ERR(us)) {
712 		status = PTR_ERR(us);
713 		goto fail;
714 	}
715 	rndis_control_intf.iInterface = us[0].id;
716 	rndis_data_intf.iInterface = us[1].id;
717 	rndis_iad_descriptor.iFunction = us[2].id;
718 
719 	/* allocate instance-specific interface IDs */
720 	status = usb_interface_id(c, f);
721 	if (status < 0)
722 		goto fail;
723 	rndis->ctrl_id = status;
724 	rndis_iad_descriptor.bFirstInterface = status;
725 
726 	rndis_control_intf.bInterfaceNumber = status;
727 	rndis_union_desc.bMasterInterface0 = status;
728 
729 	if (cdev->use_os_string)
730 		f->os_desc_table[0].if_id =
731 			rndis_iad_descriptor.bFirstInterface;
732 
733 	status = usb_interface_id(c, f);
734 	if (status < 0)
735 		goto fail;
736 	rndis->data_id = status;
737 
738 	rndis_data_intf.bInterfaceNumber = status;
739 	rndis_union_desc.bSlaveInterface0 = status;
740 
741 	status = -ENODEV;
742 
743 	/* allocate instance-specific endpoints */
744 	ep = usb_ep_autoconfig(cdev->gadget, &fs_in_desc);
745 	if (!ep)
746 		goto fail;
747 	rndis->port.in_ep = ep;
748 
749 	ep = usb_ep_autoconfig(cdev->gadget, &fs_out_desc);
750 	if (!ep)
751 		goto fail;
752 	rndis->port.out_ep = ep;
753 
754 	/* NOTE:  a status/notification endpoint is, strictly speaking,
755 	 * optional.  We don't treat it that way though!  It's simpler,
756 	 * and some newer profiles don't treat it as optional.
757 	 */
758 	ep = usb_ep_autoconfig(cdev->gadget, &fs_notify_desc);
759 	if (!ep)
760 		goto fail;
761 	rndis->notify = ep;
762 
763 	status = -ENOMEM;
764 
765 	/* allocate notification request and buffer */
766 	rndis->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
767 	if (!rndis->notify_req)
768 		goto fail;
769 	rndis->notify_req->buf = kmalloc(STATUS_BYTECOUNT, GFP_KERNEL);
770 	if (!rndis->notify_req->buf)
771 		goto fail;
772 	rndis->notify_req->length = STATUS_BYTECOUNT;
773 	rndis->notify_req->context = rndis;
774 	rndis->notify_req->complete = rndis_response_complete;
775 
776 	/* support all relevant hardware speeds... we expect that when
777 	 * hardware is dual speed, all bulk-capable endpoints work at
778 	 * both speeds
779 	 */
780 	hs_in_desc.bEndpointAddress = fs_in_desc.bEndpointAddress;
781 	hs_out_desc.bEndpointAddress = fs_out_desc.bEndpointAddress;
782 	hs_notify_desc.bEndpointAddress = fs_notify_desc.bEndpointAddress;
783 
784 	ss_in_desc.bEndpointAddress = fs_in_desc.bEndpointAddress;
785 	ss_out_desc.bEndpointAddress = fs_out_desc.bEndpointAddress;
786 	ss_notify_desc.bEndpointAddress = fs_notify_desc.bEndpointAddress;
787 
788 	status = usb_assign_descriptors(f, eth_fs_function, eth_hs_function,
789 			eth_ss_function, NULL);
790 	if (status)
791 		goto fail;
792 
793 	rndis->port.open = rndis_open;
794 	rndis->port.close = rndis_close;
795 
796 	rndis_set_param_medium(rndis->params, RNDIS_MEDIUM_802_3, 0);
797 	rndis_set_host_mac(rndis->params, rndis->ethaddr);
798 
799 	if (rndis->manufacturer && rndis->vendorID &&
800 			rndis_set_param_vendor(rndis->params, rndis->vendorID,
801 					       rndis->manufacturer)) {
802 		status = -EINVAL;
803 		goto fail_free_descs;
804 	}
805 
806 	/* NOTE:  all that is done without knowing or caring about
807 	 * the network link ... which is unavailable to this code
808 	 * until we're activated via set_alt().
809 	 */
810 
811 	DBG(cdev, "RNDIS: %s speed IN/%s OUT/%s NOTIFY/%s\n",
812 			gadget_is_superspeed(c->cdev->gadget) ? "super" :
813 			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
814 			rndis->port.in_ep->name, rndis->port.out_ep->name,
815 			rndis->notify->name);
816 	return 0;
817 
818 fail_free_descs:
819 	usb_free_all_descriptors(f);
820 fail:
821 	kfree(f->os_desc_table);
822 	f->os_desc_n = 0;
823 
824 	if (rndis->notify_req) {
825 		kfree(rndis->notify_req->buf);
826 		usb_ep_free_request(rndis->notify, rndis->notify_req);
827 	}
828 
829 	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
830 
831 	return status;
832 }
833 
834 void rndis_borrow_net(struct usb_function_instance *f, struct net_device *net)
835 {
836 	struct f_rndis_opts *opts;
837 
838 	opts = container_of(f, struct f_rndis_opts, func_inst);
839 	if (opts->bound)
840 		gether_cleanup(netdev_priv(opts->net));
841 	else
842 		free_netdev(opts->net);
843 	opts->borrowed_net = opts->bound = true;
844 	opts->net = net;
845 }
846 EXPORT_SYMBOL_GPL(rndis_borrow_net);
847 
848 static inline struct f_rndis_opts *to_f_rndis_opts(struct config_item *item)
849 {
850 	return container_of(to_config_group(item), struct f_rndis_opts,
851 			    func_inst.group);
852 }
853 
854 /* f_rndis_item_ops */
855 USB_ETHERNET_CONFIGFS_ITEM(rndis);
856 
857 /* f_rndis_opts_dev_addr */
858 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(rndis);
859 
860 /* f_rndis_opts_host_addr */
861 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(rndis);
862 
863 /* f_rndis_opts_qmult */
864 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(rndis);
865 
866 /* f_rndis_opts_ifname */
867 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(rndis);
868 
869 /* f_rndis_opts_class */
870 USB_ETHER_CONFIGFS_ITEM_ATTR_U8_RW(rndis, class);
871 
872 /* f_rndis_opts_subclass */
873 USB_ETHER_CONFIGFS_ITEM_ATTR_U8_RW(rndis, subclass);
874 
875 /* f_rndis_opts_protocol */
876 USB_ETHER_CONFIGFS_ITEM_ATTR_U8_RW(rndis, protocol);
877 
878 static struct configfs_attribute *rndis_attrs[] = {
879 	&rndis_opts_attr_dev_addr,
880 	&rndis_opts_attr_host_addr,
881 	&rndis_opts_attr_qmult,
882 	&rndis_opts_attr_ifname,
883 	&rndis_opts_attr_class,
884 	&rndis_opts_attr_subclass,
885 	&rndis_opts_attr_protocol,
886 	NULL,
887 };
888 
889 static const struct config_item_type rndis_func_type = {
890 	.ct_item_ops	= &rndis_item_ops,
891 	.ct_attrs	= rndis_attrs,
892 	.ct_owner	= THIS_MODULE,
893 };
894 
895 static void rndis_free_inst(struct usb_function_instance *f)
896 {
897 	struct f_rndis_opts *opts;
898 
899 	opts = container_of(f, struct f_rndis_opts, func_inst);
900 	if (!opts->borrowed_net) {
901 		if (opts->bound)
902 			gether_cleanup(netdev_priv(opts->net));
903 		else
904 			free_netdev(opts->net);
905 	}
906 
907 	kfree(opts->rndis_interf_group);	/* single VLA chunk */
908 	kfree(opts);
909 }
910 
911 static struct usb_function_instance *rndis_alloc_inst(void)
912 {
913 	struct f_rndis_opts *opts;
914 	struct usb_os_desc *descs[1];
915 	char *names[1];
916 	struct config_group *rndis_interf_group;
917 
918 	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
919 	if (!opts)
920 		return ERR_PTR(-ENOMEM);
921 	opts->rndis_os_desc.ext_compat_id = opts->rndis_ext_compat_id;
922 
923 	mutex_init(&opts->lock);
924 	opts->func_inst.free_func_inst = rndis_free_inst;
925 	opts->net = gether_setup_default();
926 	if (IS_ERR(opts->net)) {
927 		struct net_device *net = opts->net;
928 		kfree(opts);
929 		return ERR_CAST(net);
930 	}
931 	INIT_LIST_HEAD(&opts->rndis_os_desc.ext_prop);
932 
933 	opts->class = rndis_iad_descriptor.bFunctionClass;
934 	opts->subclass = rndis_iad_descriptor.bFunctionSubClass;
935 	opts->protocol = rndis_iad_descriptor.bFunctionProtocol;
936 
937 	descs[0] = &opts->rndis_os_desc;
938 	names[0] = "rndis";
939 	config_group_init_type_name(&opts->func_inst.group, "",
940 				    &rndis_func_type);
941 	rndis_interf_group =
942 		usb_os_desc_prepare_interf_dir(&opts->func_inst.group, 1, descs,
943 					       names, THIS_MODULE);
944 	if (IS_ERR(rndis_interf_group)) {
945 		rndis_free_inst(&opts->func_inst);
946 		return ERR_CAST(rndis_interf_group);
947 	}
948 	opts->rndis_interf_group = rndis_interf_group;
949 
950 	return &opts->func_inst;
951 }
952 
953 static void rndis_free(struct usb_function *f)
954 {
955 	struct f_rndis *rndis;
956 	struct f_rndis_opts *opts;
957 
958 	rndis = func_to_rndis(f);
959 	rndis_deregister(rndis->params);
960 	opts = container_of(f->fi, struct f_rndis_opts, func_inst);
961 	kfree(rndis);
962 	mutex_lock(&opts->lock);
963 	opts->refcnt--;
964 	mutex_unlock(&opts->lock);
965 }
966 
967 static void rndis_unbind(struct usb_configuration *c, struct usb_function *f)
968 {
969 	struct f_rndis		*rndis = func_to_rndis(f);
970 
971 	kfree(f->os_desc_table);
972 	f->os_desc_n = 0;
973 	usb_free_all_descriptors(f);
974 
975 	kfree(rndis->notify_req->buf);
976 	usb_ep_free_request(rndis->notify, rndis->notify_req);
977 }
978 
979 static struct usb_function *rndis_alloc(struct usb_function_instance *fi)
980 {
981 	struct f_rndis	*rndis;
982 	struct f_rndis_opts *opts;
983 	struct rndis_params *params;
984 
985 	/* allocate and initialize one new instance */
986 	rndis = kzalloc(sizeof(*rndis), GFP_KERNEL);
987 	if (!rndis)
988 		return ERR_PTR(-ENOMEM);
989 
990 	opts = container_of(fi, struct f_rndis_opts, func_inst);
991 	mutex_lock(&opts->lock);
992 	opts->refcnt++;
993 
994 	gether_get_host_addr_u8(opts->net, rndis->ethaddr);
995 	rndis->vendorID = opts->vendor_id;
996 	rndis->manufacturer = opts->manufacturer;
997 
998 	rndis->port.ioport = netdev_priv(opts->net);
999 	mutex_unlock(&opts->lock);
1000 	/* RNDIS activates when the host changes this filter */
1001 	rndis->port.cdc_filter = 0;
1002 
1003 	/* RNDIS has special (and complex) framing */
1004 	rndis->port.header_len = sizeof(struct rndis_packet_msg_type);
1005 	rndis->port.wrap = rndis_add_header;
1006 	rndis->port.unwrap = rndis_rm_hdr;
1007 
1008 	rndis->port.func.name = "rndis";
1009 	/* descriptors are per-instance copies */
1010 	rndis->port.func.bind = rndis_bind;
1011 	rndis->port.func.unbind = rndis_unbind;
1012 	rndis->port.func.set_alt = rndis_set_alt;
1013 	rndis->port.func.setup = rndis_setup;
1014 	rndis->port.func.disable = rndis_disable;
1015 	rndis->port.func.free_func = rndis_free;
1016 
1017 	params = rndis_register(rndis_response_available, rndis);
1018 	if (IS_ERR(params)) {
1019 		kfree(rndis);
1020 		return ERR_CAST(params);
1021 	}
1022 	rndis->params = params;
1023 
1024 	return &rndis->port.func;
1025 }
1026 
1027 DECLARE_USB_FUNCTION_INIT(rndis, rndis_alloc_inst, rndis_alloc);
1028 MODULE_LICENSE("GPL");
1029 MODULE_AUTHOR("David Brownell");
1030