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1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * This file define the new driver API for Wireless Extensions
4  *
5  * Version :	8	16.3.07
6  *
7  * Authors :	Jean Tourrilhes - HPL - <jt@hpl.hp.com>
8  * Copyright (c) 2001-2007 Jean Tourrilhes, All Rights Reserved.
9  */
10 
11 #ifndef _IW_HANDLER_H
12 #define _IW_HANDLER_H
13 
14 /************************** DOCUMENTATION **************************/
15 /*
16  * Initial driver API (1996 -> onward) :
17  * -----------------------------------
18  * The initial API just sends the IOCTL request received from user space
19  * to the driver (via the driver ioctl handler). The driver has to
20  * handle all the rest...
21  *
22  * The initial API also defines a specific handler in struct net_device
23  * to handle wireless statistics.
24  *
25  * The initial APIs served us well and has proven a reasonably good design.
26  * However, there is a few shortcommings :
27  *	o No events, everything is a request to the driver.
28  *	o Large ioctl function in driver with gigantic switch statement
29  *	  (i.e. spaghetti code).
30  *	o Driver has to mess up with copy_to/from_user, and in many cases
31  *	  does it unproperly. Common mistakes are :
32  *		* buffer overflows (no checks or off by one checks)
33  *		* call copy_to/from_user with irq disabled
34  *	o The user space interface is tied to ioctl because of the use
35  *	  copy_to/from_user.
36  *
37  * New driver API (2002 -> onward) :
38  * -------------------------------
39  * The new driver API is just a bunch of standard functions (handlers),
40  * each handling a specific Wireless Extension. The driver just export
41  * the list of handler it supports, and those will be called apropriately.
42  *
43  * I tried to keep the main advantage of the previous API (simplicity,
44  * efficiency and light weight), and also I provide a good dose of backward
45  * compatibility (most structures are the same, driver can use both API
46  * simultaneously, ...).
47  * Hopefully, I've also addressed the shortcomming of the initial API.
48  *
49  * The advantage of the new API are :
50  *	o Handling of Extensions in driver broken in small contained functions
51  *	o Tighter checks of ioctl before calling the driver
52  *	o Flexible commit strategy (at least, the start of it)
53  *	o Backward compatibility (can be mixed with old API)
54  *	o Driver doesn't have to worry about memory and user-space issues
55  * The last point is important for the following reasons :
56  *	o You are now able to call the new driver API from any API you
57  *		want (including from within other parts of the kernel).
58  *	o Common mistakes are avoided (buffer overflow, user space copy
59  *		with irq disabled and so on).
60  *
61  * The Drawback of the new API are :
62  *	o bloat (especially kernel)
63  *	o need to migrate existing drivers to new API
64  * My initial testing shows that the new API adds around 3kB to the kernel
65  * and save between 0 and 5kB from a typical driver.
66  * Also, as all structures and data types are unchanged, the migration is
67  * quite straightforward (but tedious).
68  *
69  * ---
70  *
71  * The new driver API is defined below in this file. User space should
72  * not be aware of what's happening down there...
73  *
74  * A new kernel wrapper is in charge of validating the IOCTLs and calling
75  * the appropriate driver handler. This is implemented in :
76  *	# net/core/wireless.c
77  *
78  * The driver export the list of handlers in :
79  *	# include/linux/netdevice.h (one place)
80  *
81  * The new driver API is available for WIRELESS_EXT >= 13.
82  * Good luck with migration to the new API ;-)
83  */
84 
85 /* ---------------------- THE IMPLEMENTATION ---------------------- */
86 /*
87  * Some of the choice I've made are pretty controversials. Defining an
88  * API is very much weighting compromises. This goes into some of the
89  * details and the thinking behind the implementation.
90  *
91  * Implementation goals :
92  * --------------------
93  * The implementation goals were as follow :
94  *	o Obvious : you should not need a PhD to understand what's happening,
95  *		the benefit is easier maintenance.
96  *	o Flexible : it should accommodate a wide variety of driver
97  *		implementations and be as flexible as the old API.
98  *	o Lean : it should be efficient memory wise to minimise the impact
99  *		on kernel footprint.
100  *	o Transparent to user space : the large number of user space
101  *		applications that use Wireless Extensions should not need
102  *		any modifications.
103  *
104  * Array of functions versus Struct of functions
105  * ---------------------------------------------
106  * 1) Having an array of functions allow the kernel code to access the
107  * handler in a single lookup, which is much more efficient (think hash
108  * table here).
109  * 2) The only drawback is that driver writer may put their handler in
110  * the wrong slot. This is trivial to test (I set the frequency, the
111  * bitrate changes). Once the handler is in the proper slot, it will be
112  * there forever, because the array is only extended at the end.
113  * 3) Backward/forward compatibility : adding new handler just require
114  * extending the array, so you can put newer driver in older kernel
115  * without having to patch the kernel code (and vice versa).
116  *
117  * All handler are of the same generic type
118  * ----------------------------------------
119  * That's a feature !!!
120  * 1) Having a generic handler allow to have generic code, which is more
121  * efficient. If each of the handler was individually typed I would need
122  * to add a big switch in the kernel (== more bloat). This solution is
123  * more scalable, adding new Wireless Extensions doesn't add new code.
124  * 2) You can use the same handler in different slots of the array. For
125  * hardware, it may be more efficient or logical to handle multiple
126  * Wireless Extensions with a single function, and the API allow you to
127  * do that. (An example would be a single record on the card to control
128  * both bitrate and frequency, the handler would read the old record,
129  * modify it according to info->cmd and rewrite it).
130  *
131  * Functions prototype uses union iwreq_data
132  * -----------------------------------------
133  * Some would have preferred functions defined this way :
134  *	static int mydriver_ioctl_setrate(struct net_device *dev,
135  *					  long rate, int auto)
136  * 1) The kernel code doesn't "validate" the content of iwreq_data, and
137  * can't do it (different hardware may have different notion of what a
138  * valid frequency is), so we don't pretend that we do it.
139  * 2) The above form is not extendable. If I want to add a flag (for
140  * example to distinguish setting max rate and basic rate), I would
141  * break the prototype. Using iwreq_data is more flexible.
142  * 3) Also, the above form is not generic (see above).
143  * 4) I don't expect driver developper using the wrong field of the
144  * union (Doh !), so static typechecking doesn't add much value.
145  * 5) Lastly, you can skip the union by doing :
146  *	static int mydriver_ioctl_setrate(struct net_device *dev,
147  *					  struct iw_request_info *info,
148  *					  struct iw_param *rrq,
149  *					  char *extra)
150  * And then adding the handler in the array like this :
151  *        (iw_handler) mydriver_ioctl_setrate,             // SIOCSIWRATE
152  *
153  * Using functions and not a registry
154  * ----------------------------------
155  * Another implementation option would have been for every instance to
156  * define a registry (a struct containing all the Wireless Extensions)
157  * and only have a function to commit the registry to the hardware.
158  * 1) This approach can be emulated by the current code, but not
159  * vice versa.
160  * 2) Some drivers don't keep any configuration in the driver, for them
161  * adding such a registry would be a significant bloat.
162  * 3) The code to translate from Wireless Extension to native format is
163  * needed anyway, so it would not reduce significantely the amount of code.
164  * 4) The current approach only selectively translate Wireless Extensions
165  * to native format and only selectively set, whereas the registry approach
166  * would require to translate all WE and set all parameters for any single
167  * change.
168  * 5) For many Wireless Extensions, the GET operation return the current
169  * dynamic value, not the value that was set.
170  *
171  * This header is <net/iw_handler.h>
172  * ---------------------------------
173  * 1) This header is kernel space only and should not be exported to
174  * user space. Headers in "include/linux/" are exported, headers in
175  * "include/net/" are not.
176  *
177  * Mixed 32/64 bit issues
178  * ----------------------
179  * The Wireless Extensions are designed to be 64 bit clean, by using only
180  * datatypes with explicit storage size.
181  * There are some issues related to kernel and user space using different
182  * memory model, and in particular 64bit kernel with 32bit user space.
183  * The problem is related to struct iw_point, that contains a pointer
184  * that *may* need to be translated.
185  * This is quite messy. The new API doesn't solve this problem (it can't),
186  * but is a step in the right direction :
187  * 1) Meta data about each ioctl is easily available, so we know what type
188  * of translation is needed.
189  * 2) The move of data between kernel and user space is only done in a single
190  * place in the kernel, so adding specific hooks in there is possible.
191  * 3) In the long term, it allows to move away from using ioctl as the
192  * user space API.
193  *
194  * So many comments and so few code
195  * --------------------------------
196  * That's a feature. Comments won't bloat the resulting kernel binary.
197  */
198 
199 /***************************** INCLUDES *****************************/
200 
201 #include <linux/wireless.h>		/* IOCTL user space API */
202 #include <linux/if_ether.h>
203 
204 /***************************** VERSION *****************************/
205 /*
206  * This constant is used to know which version of the driver API is
207  * available. Hopefully, this will be pretty stable and no changes
208  * will be needed...
209  * I just plan to increment with each new version.
210  */
211 #define IW_HANDLER_VERSION	8
212 
213 /*
214  * Changes :
215  *
216  * V2 to V3
217  * --------
218  *	- Move event definition in <linux/wireless.h>
219  *	- Add Wireless Event support :
220  *		o wireless_send_event() prototype
221  *		o iwe_stream_add_event/point() inline functions
222  * V3 to V4
223  * --------
224  *	- Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
225  *
226  * V4 to V5
227  * --------
228  *	- Add new spy support : struct iw_spy_data & prototypes
229  *
230  * V5 to V6
231  * --------
232  *	- Change the way we get to spy_data method for added safety
233  *	- Remove spy #ifdef, they are always on -> cleaner code
234  *	- Add IW_DESCR_FLAG_NOMAX flag for very large requests
235  *	- Start migrating get_wireless_stats to struct iw_handler_def
236  *
237  * V6 to V7
238  * --------
239  *	- Add struct ieee80211_device pointer in struct iw_public_data
240  *	- Remove (struct iw_point *)->pointer from events and streams
241  *	- Remove spy_offset from struct iw_handler_def
242  *	- Add "check" version of event macros for ieee802.11 stack
243  *
244  * V7 to V8
245  * ----------
246  *	- Prevent leaking of kernel space in stream on 64 bits.
247  */
248 
249 /**************************** CONSTANTS ****************************/
250 
251 /* Enhanced spy support available */
252 #define IW_WIRELESS_SPY
253 #define IW_WIRELESS_THRSPY
254 
255 /* Special error message for the driver to indicate that we
256  * should do a commit after return from the iw_handler */
257 #define EIWCOMMIT	EINPROGRESS
258 
259 /* Flags available in struct iw_request_info */
260 #define IW_REQUEST_FLAG_COMPAT	0x0001	/* Compat ioctl call */
261 
262 /* Type of headers we know about (basically union iwreq_data) */
263 #define IW_HEADER_TYPE_NULL	0	/* Not available */
264 #define IW_HEADER_TYPE_CHAR	2	/* char [IFNAMSIZ] */
265 #define IW_HEADER_TYPE_UINT	4	/* __u32 */
266 #define IW_HEADER_TYPE_FREQ	5	/* struct iw_freq */
267 #define IW_HEADER_TYPE_ADDR	6	/* struct sockaddr */
268 #define IW_HEADER_TYPE_POINT	8	/* struct iw_point */
269 #define IW_HEADER_TYPE_PARAM	9	/* struct iw_param */
270 #define IW_HEADER_TYPE_QUAL	10	/* struct iw_quality */
271 
272 /* Handling flags */
273 /* Most are not implemented. I just use them as a reminder of some
274  * cool features we might need one day ;-) */
275 #define IW_DESCR_FLAG_NONE	0x0000	/* Obvious */
276 /* Wrapper level flags */
277 #define IW_DESCR_FLAG_DUMP	0x0001	/* Not part of the dump command */
278 #define IW_DESCR_FLAG_EVENT	0x0002	/* Generate an event on SET */
279 #define IW_DESCR_FLAG_RESTRICT	0x0004	/* GET : request is ROOT only */
280 				/* SET : Omit payload from generated iwevent */
281 #define IW_DESCR_FLAG_NOMAX	0x0008	/* GET : no limit on request size */
282 /* Driver level flags */
283 #define IW_DESCR_FLAG_WAIT	0x0100	/* Wait for driver event */
284 
285 /****************************** TYPES ******************************/
286 
287 /* ----------------------- WIRELESS HANDLER ----------------------- */
288 /*
289  * A wireless handler is just a standard function, that looks like the
290  * ioctl handler.
291  * We also define there how a handler list look like... As the Wireless
292  * Extension space is quite dense, we use a simple array, which is faster
293  * (that's the perfect hash table ;-).
294  */
295 
296 /*
297  * Meta data about the request passed to the iw_handler.
298  * Most handlers can safely ignore what's in there.
299  * The 'cmd' field might come handy if you want to use the same handler
300  * for multiple command...
301  * This struct is also my long term insurance. I can add new fields here
302  * without breaking the prototype of iw_handler...
303  */
304 struct iw_request_info {
305 	__u16		cmd;		/* Wireless Extension command */
306 	__u16		flags;		/* More to come ;-) */
307 };
308 
309 struct net_device;
310 
311 /*
312  * This is how a function handling a Wireless Extension should look
313  * like (both get and set, standard and private).
314  */
315 typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info,
316 			  union iwreq_data *wrqu, char *extra);
317 
318 /*
319  * This define all the handler that the driver export.
320  * As you need only one per driver type, please use a static const
321  * shared by all driver instances... Same for the members...
322  * This will be linked from net_device in <linux/netdevice.h>
323  */
324 struct iw_handler_def {
325 
326 	/* Array of handlers for standard ioctls
327 	 * We will call dev->wireless_handlers->standard[ioctl - SIOCIWFIRST]
328 	 */
329 	const iw_handler *	standard;
330 	/* Number of handlers defined (more precisely, index of the
331 	 * last defined handler + 1) */
332 	__u16			num_standard;
333 
334 #ifdef CONFIG_WEXT_PRIV
335 	__u16			num_private;
336 	/* Number of private arg description */
337 	__u16			num_private_args;
338 	/* Array of handlers for private ioctls
339 	 * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
340 	 */
341 	const iw_handler *	private;
342 
343 	/* Arguments of private handler. This one is just a list, so you
344 	 * can put it in any order you want and should not leave holes...
345 	 * We will automatically export that to user space... */
346 	const struct iw_priv_args *	private_args;
347 #endif
348 
349 	/* New location of get_wireless_stats, to de-bloat struct net_device.
350 	 * The old pointer in struct net_device will be gradually phased
351 	 * out, and drivers are encouraged to use this one... */
352 	struct iw_statistics*	(*get_wireless_stats)(struct net_device *dev);
353 };
354 
355 /* ---------------------- IOCTL DESCRIPTION ---------------------- */
356 /*
357  * One of the main goal of the new interface is to deal entirely with
358  * user space/kernel space memory move.
359  * For that, we need to know :
360  *	o if iwreq is a pointer or contain the full data
361  *	o what is the size of the data to copy
362  *
363  * For private IOCTLs, we use the same rules as used by iwpriv and
364  * defined in struct iw_priv_args.
365  *
366  * For standard IOCTLs, things are quite different and we need to
367  * use the structures below. Actually, this struct is also more
368  * efficient, but that's another story...
369  */
370 
371 /*
372  * Describe how a standard IOCTL looks like.
373  */
374 struct iw_ioctl_description {
375 	__u8	header_type;		/* NULL, iw_point or other */
376 	__u8	token_type;		/* Future */
377 	__u16	token_size;		/* Granularity of payload */
378 	__u16	min_tokens;		/* Min acceptable token number */
379 	__u16	max_tokens;		/* Max acceptable token number */
380 	__u32	flags;			/* Special handling of the request */
381 };
382 
383 /* Need to think of short header translation table. Later. */
384 
385 /* --------------------- ENHANCED SPY SUPPORT --------------------- */
386 /*
387  * In the old days, the driver was handling spy support all by itself.
388  * Now, the driver can delegate this task to Wireless Extensions.
389  * It needs to include this struct in its private part and use the
390  * standard spy iw_handler.
391  */
392 
393 /*
394  * Instance specific spy data, i.e. addresses spied and quality for them.
395  */
396 struct iw_spy_data {
397 	/* --- Standard spy support --- */
398 	int			spy_number;
399 	u_char			spy_address[IW_MAX_SPY][ETH_ALEN];
400 	struct iw_quality	spy_stat[IW_MAX_SPY];
401 	/* --- Enhanced spy support (event) */
402 	struct iw_quality	spy_thr_low;	/* Low threshold */
403 	struct iw_quality	spy_thr_high;	/* High threshold */
404 	u_char			spy_thr_under[IW_MAX_SPY];
405 };
406 
407 /* --------------------- DEVICE WIRELESS DATA --------------------- */
408 /*
409  * This is all the wireless data specific to a device instance that
410  * is managed by the core of Wireless Extensions or the 802.11 layer.
411  * We only keep pointer to those structures, so that a driver is free
412  * to share them between instances.
413  * This structure should be initialised before registering the device.
414  * Access to this data follow the same rules as any other struct net_device
415  * data (i.e. valid as long as struct net_device exist, same locking rules).
416  */
417 /* Forward declaration */
418 struct libipw_device;
419 /* The struct */
420 struct iw_public_data {
421 	/* Driver enhanced spy support */
422 	struct iw_spy_data *		spy_data;
423 	/* Legacy structure managed by the ipw2x00-specific IEEE 802.11 layer */
424 	struct libipw_device *		libipw;
425 };
426 
427 /**************************** PROTOTYPES ****************************/
428 /*
429  * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
430  * Those may be called only within the kernel.
431  */
432 
433 /* First : function strictly used inside the kernel */
434 
435 /* Handle /proc/net/wireless, called in net/code/dev.c */
436 int dev_get_wireless_info(char *buffer, char **start, off_t offset, int length);
437 
438 /* Second : functions that may be called by driver modules */
439 
440 /* Send a single event to user space */
441 void wireless_send_event(struct net_device *dev, unsigned int cmd,
442 			 union iwreq_data *wrqu, const char *extra);
443 #ifdef CONFIG_WEXT_CORE
444 /* flush all previous wext events - if work is done from netdev notifiers */
445 void wireless_nlevent_flush(void);
446 #else
wireless_nlevent_flush(void)447 static inline void wireless_nlevent_flush(void) {}
448 #endif
449 
450 /* We may need a function to send a stream of events to user space.
451  * More on that later... */
452 
453 /* Standard handler for SIOCSIWSPY */
454 int iw_handler_set_spy(struct net_device *dev, struct iw_request_info *info,
455 		       union iwreq_data *wrqu, char *extra);
456 /* Standard handler for SIOCGIWSPY */
457 int iw_handler_get_spy(struct net_device *dev, struct iw_request_info *info,
458 		       union iwreq_data *wrqu, char *extra);
459 /* Standard handler for SIOCSIWTHRSPY */
460 int iw_handler_set_thrspy(struct net_device *dev, struct iw_request_info *info,
461 			  union iwreq_data *wrqu, char *extra);
462 /* Standard handler for SIOCGIWTHRSPY */
463 int iw_handler_get_thrspy(struct net_device *dev, struct iw_request_info *info,
464 			  union iwreq_data *wrqu, char *extra);
465 /* Driver call to update spy records */
466 void wireless_spy_update(struct net_device *dev, unsigned char *address,
467 			 struct iw_quality *wstats);
468 
469 /************************* INLINE FUNTIONS *************************/
470 /*
471  * Function that are so simple that it's more efficient inlining them
472  */
473 
iwe_stream_lcp_len(struct iw_request_info * info)474 static inline int iwe_stream_lcp_len(struct iw_request_info *info)
475 {
476 #ifdef CONFIG_COMPAT
477 	if (info->flags & IW_REQUEST_FLAG_COMPAT)
478 		return IW_EV_COMPAT_LCP_LEN;
479 #endif
480 	return IW_EV_LCP_LEN;
481 }
482 
iwe_stream_point_len(struct iw_request_info * info)483 static inline int iwe_stream_point_len(struct iw_request_info *info)
484 {
485 #ifdef CONFIG_COMPAT
486 	if (info->flags & IW_REQUEST_FLAG_COMPAT)
487 		return IW_EV_COMPAT_POINT_LEN;
488 #endif
489 	return IW_EV_POINT_LEN;
490 }
491 
iwe_stream_event_len_adjust(struct iw_request_info * info,int event_len)492 static inline int iwe_stream_event_len_adjust(struct iw_request_info *info,
493 					      int event_len)
494 {
495 #ifdef CONFIG_COMPAT
496 	if (info->flags & IW_REQUEST_FLAG_COMPAT) {
497 		event_len -= IW_EV_LCP_LEN;
498 		event_len += IW_EV_COMPAT_LCP_LEN;
499 	}
500 #endif
501 
502 	return event_len;
503 }
504 
505 /*------------------------------------------------------------------*/
506 /*
507  * Wrapper to add an Wireless Event to a stream of events.
508  */
509 char *iwe_stream_add_event(struct iw_request_info *info, char *stream,
510 			   char *ends, struct iw_event *iwe, int event_len);
511 
512 static inline char *
iwe_stream_add_event_check(struct iw_request_info * info,char * stream,char * ends,struct iw_event * iwe,int event_len)513 iwe_stream_add_event_check(struct iw_request_info *info, char *stream,
514 			   char *ends, struct iw_event *iwe, int event_len)
515 {
516 	char *res = iwe_stream_add_event(info, stream, ends, iwe, event_len);
517 
518 	if (res == stream)
519 		return ERR_PTR(-E2BIG);
520 	return res;
521 }
522 
523 /*------------------------------------------------------------------*/
524 /*
525  * Wrapper to add an short Wireless Event containing a pointer to a
526  * stream of events.
527  */
528 char *iwe_stream_add_point(struct iw_request_info *info, char *stream,
529 			   char *ends, struct iw_event *iwe, char *extra);
530 
531 static inline char *
iwe_stream_add_point_check(struct iw_request_info * info,char * stream,char * ends,struct iw_event * iwe,char * extra)532 iwe_stream_add_point_check(struct iw_request_info *info, char *stream,
533 			   char *ends, struct iw_event *iwe, char *extra)
534 {
535 	char *res = iwe_stream_add_point(info, stream, ends, iwe, extra);
536 
537 	if (res == stream)
538 		return ERR_PTR(-E2BIG);
539 	return res;
540 }
541 
542 /*------------------------------------------------------------------*/
543 /*
544  * Wrapper to add a value to a Wireless Event in a stream of events.
545  * Be careful, this one is tricky to use properly :
546  * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
547  */
548 char *iwe_stream_add_value(struct iw_request_info *info, char *event,
549 			   char *value, char *ends, struct iw_event *iwe,
550 			   int event_len);
551 
552 #endif	/* _IW_HANDLER_H */
553