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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * This file define the new driver API for Wireless Extensions
3 *
4 * Version : 6 21.6.04
5 *
6 * Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com>
7 * Copyright (c) 2001-2004 Jean Tourrilhes, All Rights Reserved.
8 */
9
10#ifndef _IW_HANDLER_H
11#define _IW_HANDLER_H
12
13/************************** DOCUMENTATION **************************/
14/*
15 * Initial driver API (1996 -> onward) :
16 * -----------------------------------
17 * The initial API just sends the IOCTL request received from user space
18 * to the driver (via the driver ioctl handler). The driver has to
19 * handle all the rest...
20 *
21 * The initial API also defines a specific handler in struct net_device
22 * to handle wireless statistics.
23 *
24 * The initial APIs served us well and has proven a reasonably good design.
25 * However, there is a few shortcommings :
26 * o No events, everything is a request to the driver.
27 * o Large ioctl function in driver with gigantic switch statement
28 * (i.e. spaghetti code).
29 * o Driver has to mess up with copy_to/from_user, and in many cases
30 * does it unproperly. Common mistakes are :
31 * * buffer overflows (no checks or off by one checks)
32 * * call copy_to/from_user with irq disabled
33 * o The user space interface is tied to ioctl because of the use
34 * copy_to/from_user.
35 *
36 * New driver API (2002 -> onward) :
37 * -------------------------------
38 * The new driver API is just a bunch of standard functions (handlers),
39 * each handling a specific Wireless Extension. The driver just export
40 * the list of handler it supports, and those will be called apropriately.
41 *
42 * I tried to keep the main advantage of the previous API (simplicity,
43 * efficiency and light weight), and also I provide a good dose of backward
44 * compatibility (most structures are the same, driver can use both API
45 * simultaneously, ...).
46 * Hopefully, I've also addressed the shortcomming of the initial API.
47 *
48 * The advantage of the new API are :
49 * o Handling of Extensions in driver broken in small contained functions
50 * o Tighter checks of ioctl before calling the driver
51 * o Flexible commit strategy (at least, the start of it)
52 * o Backward compatibility (can be mixed with old API)
53 * o Driver doesn't have to worry about memory and user-space issues
54 * The last point is important for the following reasons :
55 * o You are now able to call the new driver API from any API you
56 * want (including from within other parts of the kernel).
57 * o Common mistakes are avoided (buffer overflow, user space copy
58 * with irq disabled and so on).
59 *
60 * The Drawback of the new API are :
61 * o bloat (especially kernel)
62 * o need to migrate existing drivers to new API
63 * My initial testing shows that the new API adds around 3kB to the kernel
64 * and save between 0 and 5kB from a typical driver.
65 * Also, as all structures and data types are unchanged, the migration is
66 * quite straightforward (but tedious).
67 *
68 * ---
69 *
70 * The new driver API is defined below in this file. User space should
71 * not be aware of what's happening down there...
72 *
73 * A new kernel wrapper is in charge of validating the IOCTLs and calling
74 * the appropriate driver handler. This is implemented in :
75 * # net/core/wireless.c
76 *
77 * The driver export the list of handlers in :
78 * # include/linux/netdevice.h (one place)
79 *
80 * The new driver API is available for WIRELESS_EXT >= 13.
81 * Good luck with migration to the new API ;-)
82 */
83
84/* ---------------------- THE IMPLEMENTATION ---------------------- */
85/*
86 * Some of the choice I've made are pretty controversials. Defining an
87 * API is very much weighting compromises. This goes into some of the
88 * details and the thinking behind the implementation.
89 *
90 * Implementation goals :
91 * --------------------
92 * The implementation goals were as follow :
93 * o Obvious : you should not need a PhD to understand what's happening,
94 * the benefit is easier maintainance.
95 * o Flexible : it should accommodate a wide variety of driver
96 * implementations and be as flexible as the old API.
97 * o Lean : it should be efficient memory wise to minimise the impact
98 * on kernel footprint.
99 * o Transparent to user space : the large number of user space
100 * applications that use Wireless Extensions should not need
101 * any modifications.
102 *
103 * Array of functions versus Struct of functions
104 * ---------------------------------------------
105 * 1) Having an array of functions allow the kernel code to access the
106 * handler in a single lookup, which is much more efficient (think hash
107 * table here).
108 * 2) The only drawback is that driver writer may put their handler in
109 * the wrong slot. This is trivial to test (I set the frequency, the
110 * bitrate changes). Once the handler is in the proper slot, it will be
111 * there forever, because the array is only extended at the end.
112 * 3) Backward/forward compatibility : adding new handler just require
113 * extending the array, so you can put newer driver in older kernel
114 * without having to patch the kernel code (and vice versa).
115 *
116 * All handler are of the same generic type
117 * ----------------------------------------
118 * That's a feature !!!
119 * 1) Having a generic handler allow to have generic code, which is more
120 * efficient. If each of the handler was individually typed I would need
121 * to add a big switch in the kernel (== more bloat). This solution is
122 * more scalable, adding new Wireless Extensions doesn't add new code.
123 * 2) You can use the same handler in different slots of the array. For
124 * hardware, it may be more efficient or logical to handle multiple
125 * Wireless Extensions with a single function, and the API allow you to
126 * do that. (An example would be a single record on the card to control
127 * both bitrate and frequency, the handler would read the old record,
128 * modify it according to info->cmd and rewrite it).
129 *
130 * Functions prototype uses union iwreq_data
131 * -----------------------------------------
132 * Some would have prefered functions defined this way :
133 * static int mydriver_ioctl_setrate(struct net_device *dev,
134 * long rate, int auto)
135 * 1) The kernel code doesn't "validate" the content of iwreq_data, and
136 * can't do it (different hardware may have different notion of what a
137 * valid frequency is), so we don't pretend that we do it.
138 * 2) The above form is not extendable. If I want to add a flag (for
139 * example to distinguish setting max rate and basic rate), I would
140 * break the prototype. Using iwreq_data is more flexible.
141 * 3) Also, the above form is not generic (see above).
142 * 4) I don't expect driver developper using the wrong field of the
143 * union (Doh !), so static typechecking doesn't add much value.
144 * 5) Lastly, you can skip the union by doing :
145 * static int mydriver_ioctl_setrate(struct net_device *dev,
146 * struct iw_request_info *info,
147 * struct iw_param *rrq,
148 * char *extra)
149 * And then adding the handler in the array like this :
150 * (iw_handler) mydriver_ioctl_setrate, // SIOCSIWRATE
151 *
152 * Using functions and not a registry
153 * ----------------------------------
154 * Another implementation option would have been for every instance to
155 * define a registry (a struct containing all the Wireless Extensions)
156 * and only have a function to commit the registry to the hardware.
157 * 1) This approach can be emulated by the current code, but not
158 * vice versa.
159 * 2) Some drivers don't keep any configuration in the driver, for them
160 * adding such a registry would be a significant bloat.
161 * 3) The code to translate from Wireless Extension to native format is
162 * needed anyway, so it would not reduce significantely the amount of code.
163 * 4) The current approach only selectively translate Wireless Extensions
164 * to native format and only selectively set, whereas the registry approach
165 * would require to translate all WE and set all parameters for any single
166 * change.
167 * 5) For many Wireless Extensions, the GET operation return the current
168 * dynamic value, not the value that was set.
169 *
170 * This header is <net/iw_handler.h>
171 * ---------------------------------
172 * 1) This header is kernel space only and should not be exported to
173 * user space. Headers in "include/linux/" are exported, headers in
174 * "include/net/" are not.
175 *
176 * Mixed 32/64 bit issues
177 * ----------------------
178 * The Wireless Extensions are designed to be 64 bit clean, by using only
179 * datatypes with explicit storage size.
180 * There are some issues related to kernel and user space using different
181 * memory model, and in particular 64bit kernel with 32bit user space.
182 * The problem is related to struct iw_point, that contains a pointer
183 * that *may* need to be translated.
184 * This is quite messy. The new API doesn't solve this problem (it can't),
185 * but is a step in the right direction :
186 * 1) Meta data about each ioctl is easily available, so we know what type
187 * of translation is needed.
188 * 2) The move of data between kernel and user space is only done in a single
189 * place in the kernel, so adding specific hooks in there is possible.
190 * 3) In the long term, it allows to move away from using ioctl as the
191 * user space API.
192 *
193 * So many comments and so few code
194 * --------------------------------
195 * That's a feature. Comments won't bloat the resulting kernel binary.
196 */
197
198/***************************** INCLUDES *****************************/
199
200#include <linux/wireless.h> /* IOCTL user space API */
201#include <linux/if_ether.h>
202
203/***************************** VERSION *****************************/
204/*
205 * This constant is used to know which version of the driver API is
206 * available. Hopefully, this will be pretty stable and no changes
207 * will be needed...
208 * I just plan to increment with each new version.
209 */
210#define IW_HANDLER_VERSION 6
211
212/*
213 * Changes :
214 *
215 * V2 to V3
216 * --------
217 * - Move event definition in <linux/wireless.h>
218 * - Add Wireless Event support :
219 * o wireless_send_event() prototype
220 * o iwe_stream_add_event/point() inline functions
221 * V3 to V4
222 * --------
223 * - Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
224 *
225 * V4 to V5
226 * --------
227 * - Add new spy support : struct iw_spy_data & prototypes
228 *
229 * V5 to V6
230 * --------
231 * - Change the way we get to spy_data method for added safety
232 * - Remove spy #ifdef, they are always on -> cleaner code
233 * - Add IW_DESCR_FLAG_NOMAX flag for very large requests
234 * - Start migrating get_wireless_stats to struct iw_handler_def
235 */
236
237/**************************** CONSTANTS ****************************/
238
239/* Enhanced spy support available */
240#define IW_WIRELESS_SPY
241#define IW_WIRELESS_THRSPY
242
243/* Special error message for the driver to indicate that we
244 * should do a commit after return from the iw_handler */
245#define EIWCOMMIT EINPROGRESS
246
247/* Flags available in struct iw_request_info */
248#define IW_REQUEST_FLAG_NONE 0x0000 /* No flag so far */
249
250/* Type of headers we know about (basically union iwreq_data) */
251#define IW_HEADER_TYPE_NULL 0 /* Not available */
252#define IW_HEADER_TYPE_CHAR 2 /* char [IFNAMSIZ] */
253#define IW_HEADER_TYPE_UINT 4 /* __u32 */
254#define IW_HEADER_TYPE_FREQ 5 /* struct iw_freq */
255#define IW_HEADER_TYPE_ADDR 6 /* struct sockaddr */
256#define IW_HEADER_TYPE_POINT 8 /* struct iw_point */
257#define IW_HEADER_TYPE_PARAM 9 /* struct iw_param */
258#define IW_HEADER_TYPE_QUAL 10 /* struct iw_quality */
259
260/* Handling flags */
261/* Most are not implemented. I just use them as a reminder of some
262 * cool features we might need one day ;-) */
263#define IW_DESCR_FLAG_NONE 0x0000 /* Obvious */
264/* Wrapper level flags */
265#define IW_DESCR_FLAG_DUMP 0x0001 /* Not part of the dump command */
266#define IW_DESCR_FLAG_EVENT 0x0002 /* Generate an event on SET */
267#define IW_DESCR_FLAG_RESTRICT 0x0004 /* GET : request is ROOT only */
268 /* SET : Omit payload from generated iwevent */
269#define IW_DESCR_FLAG_NOMAX 0x0008 /* GET : no limit on request size */
270/* Driver level flags */
271#define IW_DESCR_FLAG_WAIT 0x0100 /* Wait for driver event */
272
273/****************************** TYPES ******************************/
274
275/* ----------------------- WIRELESS HANDLER ----------------------- */
276/*
277 * A wireless handler is just a standard function, that looks like the
278 * ioctl handler.
279 * We also define there how a handler list look like... As the Wireless
280 * Extension space is quite dense, we use a simple array, which is faster
281 * (that's the perfect hash table ;-).
282 */
283
284/*
285 * Meta data about the request passed to the iw_handler.
286 * Most handlers can safely ignore what's in there.
287 * The 'cmd' field might come handy if you want to use the same handler
288 * for multiple command...
289 * This struct is also my long term insurance. I can add new fields here
290 * without breaking the prototype of iw_handler...
291 */
292struct iw_request_info
293{
294 __u16 cmd; /* Wireless Extension command */
295 __u16 flags; /* More to come ;-) */
296};
297
298struct net_device;
299
300/*
301 * This is how a function handling a Wireless Extension should look
302 * like (both get and set, standard and private).
303 */
304typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info,
305 union iwreq_data *wrqu, char *extra);
306
307/*
308 * This define all the handler that the driver export.
309 * As you need only one per driver type, please use a static const
310 * shared by all driver instances... Same for the members...
311 * This will be linked from net_device in <linux/netdevice.h>
312 */
313struct iw_handler_def
314{
315 /* Number of handlers defined (more precisely, index of the
316 * last defined handler + 1) */
317 __u16 num_standard;
318 __u16 num_private;
319 /* Number of private arg description */
320 __u16 num_private_args;
321
322 /* Array of handlers for standard ioctls
323 * We will call dev->wireless_handlers->standard[ioctl - SIOCSIWNAME]
324 */
325 const iw_handler * standard;
326
327 /* Array of handlers for private ioctls
328 * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
329 */
330 const iw_handler * private;
331
332 /* Arguments of private handler. This one is just a list, so you
333 * can put it in any order you want and should not leave holes...
334 * We will automatically export that to user space... */
335 const struct iw_priv_args * private_args;
336
337 /* This field will be *removed* in the next version of WE */
338 long spy_offset; /* DO NOT USE */
339
340 /* New location of get_wireless_stats, to de-bloat struct net_device.
341 * The old pointer in struct net_device will be gradually phased
342 * out, and drivers are encouraged to use this one... */
343 struct iw_statistics* (*get_wireless_stats)(struct net_device *dev);
344};
345
346/* ---------------------- IOCTL DESCRIPTION ---------------------- */
347/*
348 * One of the main goal of the new interface is to deal entirely with
349 * user space/kernel space memory move.
350 * For that, we need to know :
351 * o if iwreq is a pointer or contain the full data
352 * o what is the size of the data to copy
353 *
354 * For private IOCTLs, we use the same rules as used by iwpriv and
355 * defined in struct iw_priv_args.
356 *
357 * For standard IOCTLs, things are quite different and we need to
358 * use the stuctures below. Actually, this struct is also more
359 * efficient, but that's another story...
360 */
361
362/*
363 * Describe how a standard IOCTL looks like.
364 */
365struct iw_ioctl_description
366{
367 __u8 header_type; /* NULL, iw_point or other */
368 __u8 token_type; /* Future */
369 __u16 token_size; /* Granularity of payload */
370 __u16 min_tokens; /* Min acceptable token number */
371 __u16 max_tokens; /* Max acceptable token number */
372 __u32 flags; /* Special handling of the request */
373};
374
375/* Need to think of short header translation table. Later. */
376
377/* --------------------- ENHANCED SPY SUPPORT --------------------- */
378/*
379 * In the old days, the driver was handling spy support all by itself.
380 * Now, the driver can delegate this task to Wireless Extensions.
381 * It needs to include this struct in its private part and use the
382 * standard spy iw_handler.
383 */
384
385/*
386 * Instance specific spy data, i.e. addresses spied and quality for them.
387 */
388struct iw_spy_data
389{
390 /* --- Standard spy support --- */
391 int spy_number;
392 u_char spy_address[IW_MAX_SPY][ETH_ALEN];
393 struct iw_quality spy_stat[IW_MAX_SPY];
394 /* --- Enhanced spy support (event) */
395 struct iw_quality spy_thr_low; /* Low threshold */
396 struct iw_quality spy_thr_high; /* High threshold */
397 u_char spy_thr_under[IW_MAX_SPY];
398};
399
400/* --------------------- DEVICE WIRELESS DATA --------------------- */
401/*
402 * This is all the wireless data specific to a device instance that
403 * is managed by the core of Wireless Extensions.
404 * We only keep pointer to those structures, so that a driver is free
405 * to share them between instances.
406 * This structure should be initialised before registering the device.
407 * Access to this data follow the same rules as any other struct net_device
408 * data (i.e. valid as long as struct net_device exist, same locking rules).
409 */
410struct iw_public_data {
411 /* Driver enhanced spy support */
412 struct iw_spy_data * spy_data;
413};
414
415/**************************** PROTOTYPES ****************************/
416/*
417 * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
418 * Those may be called only within the kernel.
419 */
420
421/* First : function strictly used inside the kernel */
422
423/* Handle /proc/net/wireless, called in net/code/dev.c */
424extern int dev_get_wireless_info(char * buffer, char **start, off_t offset,
425 int length);
426
427/* Handle IOCTLs, called in net/code/dev.c */
428extern int wireless_process_ioctl(struct ifreq *ifr, unsigned int cmd);
429
430/* Second : functions that may be called by driver modules */
431
432/* Send a single event to user space */
433extern void wireless_send_event(struct net_device * dev,
434 unsigned int cmd,
435 union iwreq_data * wrqu,
436 char * extra);
437
438/* We may need a function to send a stream of events to user space.
439 * More on that later... */
440
441/* Standard handler for SIOCSIWSPY */
442extern int iw_handler_set_spy(struct net_device * dev,
443 struct iw_request_info * info,
444 union iwreq_data * wrqu,
445 char * extra);
446/* Standard handler for SIOCGIWSPY */
447extern int iw_handler_get_spy(struct net_device * dev,
448 struct iw_request_info * info,
449 union iwreq_data * wrqu,
450 char * extra);
451/* Standard handler for SIOCSIWTHRSPY */
452extern int iw_handler_set_thrspy(struct net_device * dev,
453 struct iw_request_info *info,
454 union iwreq_data * wrqu,
455 char * extra);
456/* Standard handler for SIOCGIWTHRSPY */
457extern int iw_handler_get_thrspy(struct net_device * dev,
458 struct iw_request_info *info,
459 union iwreq_data * wrqu,
460 char * extra);
461/* Driver call to update spy records */
462extern void wireless_spy_update(struct net_device * dev,
463 unsigned char * address,
464 struct iw_quality * wstats);
465
466/************************* INLINE FUNTIONS *************************/
467/*
468 * Function that are so simple that it's more efficient inlining them
469 */
470
471/*------------------------------------------------------------------*/
472/*
473 * Wrapper to add an Wireless Event to a stream of events.
474 */
475static inline char *
476iwe_stream_add_event(char * stream, /* Stream of events */
477 char * ends, /* End of stream */
478 struct iw_event *iwe, /* Payload */
479 int event_len) /* Real size of payload */
480{
481 /* Check if it's possible */
482 if((stream + event_len) < ends) {
483 iwe->len = event_len;
484 memcpy(stream, (char *) iwe, event_len);
485 stream += event_len;
486 }
487 return stream;
488}
489
490/*------------------------------------------------------------------*/
491/*
492 * Wrapper to add an short Wireless Event containing a pointer to a
493 * stream of events.
494 */
495static inline char *
496iwe_stream_add_point(char * stream, /* Stream of events */
497 char * ends, /* End of stream */
498 struct iw_event *iwe, /* Payload */
499 char * extra)
500{
501 int event_len = IW_EV_POINT_LEN + iwe->u.data.length;
502 /* Check if it's possible */
503 if((stream + event_len) < ends) {
504 iwe->len = event_len;
505 memcpy(stream, (char *) iwe, IW_EV_POINT_LEN);
506 memcpy(stream + IW_EV_POINT_LEN, extra, iwe->u.data.length);
507 stream += event_len;
508 }
509 return stream;
510}
511
512/*------------------------------------------------------------------*/
513/*
514 * Wrapper to add a value to a Wireless Event in a stream of events.
515 * Be careful, this one is tricky to use properly :
516 * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
517 */
518static inline char *
519iwe_stream_add_value(char * event, /* Event in the stream */
520 char * value, /* Value in event */
521 char * ends, /* End of stream */
522 struct iw_event *iwe, /* Payload */
523 int event_len) /* Real size of payload */
524{
525 /* Don't duplicate LCP */
526 event_len -= IW_EV_LCP_LEN;
527
528 /* Check if it's possible */
529 if((value + event_len) < ends) {
530 /* Add new value */
531 memcpy(value, (char *) iwe + IW_EV_LCP_LEN, event_len);
532 value += event_len;
533 /* Patch LCP */
534 iwe->len = value - event;
535 memcpy(event, (char *) iwe, IW_EV_LCP_LEN);
536 }
537 return value;
538}
539
540#endif /* _IW_HANDLER_H */