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 */
304struct iw_request_info {
305 __u16 cmd; /* Wireless Extension command */
306 __u16 flags; /* More to come ;-) */
307};
308
309struct 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 */
315typedef 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 */
324struct 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 */
374struct 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 */
396struct 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 */
418struct libipw_device;
419/* The struct */
420struct 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 */
436int 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 */
441void 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 */
445void wireless_nlevent_flush(void);
446#else
447static 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 */
454int 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 */
457int 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 */
460int 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 */
463int 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 */
466void 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
474static 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
483static 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
492static 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 */
509char *iwe_stream_add_event(struct iw_request_info *info, char *stream,
510 char *ends, struct iw_event *iwe, int event_len);
511
512static inline char *
513iwe_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 */
528char *iwe_stream_add_point(struct iw_request_info *info, char *stream,
529 char *ends, struct iw_event *iwe, char *extra);
530
531static inline char *
532iwe_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 */
548char *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

source code of linux/include/net/iw_handler.h