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2 * This file define the new driver API for Wireless Extensions
6 * Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com>
7 * Copyright (c) 2001-2007 Jean Tourrilhes, All Rights Reserved.
13 /************************** DOCUMENTATION **************************/
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...
21 * The initial API also defines a specific handler in struct net_device
22 * to handle wireless statistics.
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
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.
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.
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).
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).
70 * The new driver API is defined below in this file. User space should
71 * not be aware of what's happening down there...
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
77 * The driver export the list of handlers in :
78 * # include/linux/netdevice.h (one place)
80 * The new driver API is available for WIRELESS_EXT >= 13.
81 * Good luck with migration to the new API ;-)
84 /* ---------------------- THE IMPLEMENTATION ---------------------- */
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.
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
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
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).
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).
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,
149 * And then adding the handler in the array like this :
150 * (iw_handler) mydriver_ioctl_setrate, // SIOCSIWRATE
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
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
167 * 5) For many Wireless Extensions, the GET operation return the current
168 * dynamic value, not the value that was set.
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.
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
193 * So many comments and so few code
194 * --------------------------------
195 * That's a feature. Comments won't bloat the resulting kernel binary.
198 /***************************** INCLUDES *****************************/
200 #include <linux/wireless.h> /* IOCTL user space API */
201 #include <linux/if_ether.h>
203 /***************************** VERSION *****************************/
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
208 * I just plan to increment with each new version.
210 #define IW_HANDLER_VERSION 8
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
223 * - Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
227 * - Add new spy support : struct iw_spy_data & prototypes
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
238 * - Add struct ieee80211_device pointer in struct iw_public_data
239 * - Remove (struct iw_point *)->pointer from events and streams
240 * - Remove spy_offset from struct iw_handler_def
241 * - Add "check" version of event macros for ieee802.11 stack
245 * - Prevent leaking of kernel space in stream on 64 bits.
248 /**************************** CONSTANTS ****************************/
250 /* Enhanced spy support available */
251 #define IW_WIRELESS_SPY
252 #define IW_WIRELESS_THRSPY
254 /* Special error message for the driver to indicate that we
255 * should do a commit after return from the iw_handler */
256 #define EIWCOMMIT EINPROGRESS
258 /* Flags available in struct iw_request_info */
259 #define IW_REQUEST_FLAG_COMPAT 0x0001 /* Compat ioctl call */
261 /* Type of headers we know about (basically union iwreq_data) */
262 #define IW_HEADER_TYPE_NULL 0 /* Not available */
263 #define IW_HEADER_TYPE_CHAR 2 /* char [IFNAMSIZ] */
264 #define IW_HEADER_TYPE_UINT 4 /* __u32 */
265 #define IW_HEADER_TYPE_FREQ 5 /* struct iw_freq */
266 #define IW_HEADER_TYPE_ADDR 6 /* struct sockaddr */
267 #define IW_HEADER_TYPE_POINT 8 /* struct iw_point */
268 #define IW_HEADER_TYPE_PARAM 9 /* struct iw_param */
269 #define IW_HEADER_TYPE_QUAL 10 /* struct iw_quality */
272 /* Most are not implemented. I just use them as a reminder of some
273 * cool features we might need one day ;-) */
274 #define IW_DESCR_FLAG_NONE 0x0000 /* Obvious */
275 /* Wrapper level flags */
276 #define IW_DESCR_FLAG_DUMP 0x0001 /* Not part of the dump command */
277 #define IW_DESCR_FLAG_EVENT 0x0002 /* Generate an event on SET */
278 #define IW_DESCR_FLAG_RESTRICT 0x0004 /* GET : request is ROOT only */
279 /* SET : Omit payload from generated iwevent */
280 #define IW_DESCR_FLAG_NOMAX 0x0008 /* GET : no limit on request size */
281 /* Driver level flags */
282 #define IW_DESCR_FLAG_WAIT 0x0100 /* Wait for driver event */
284 /****************************** TYPES ******************************/
286 /* ----------------------- WIRELESS HANDLER ----------------------- */
288 * A wireless handler is just a standard function, that looks like the
290 * We also define there how a handler list look like... As the Wireless
291 * Extension space is quite dense, we use a simple array, which is faster
292 * (that's the perfect hash table ;-).
296 * Meta data about the request passed to the iw_handler.
297 * Most handlers can safely ignore what's in there.
298 * The 'cmd' field might come handy if you want to use the same handler
299 * for multiple command...
300 * This struct is also my long term insurance. I can add new fields here
301 * without breaking the prototype of iw_handler...
303 struct iw_request_info
305 __u16 cmd
; /* Wireless Extension command */
306 __u16 flags
; /* More to come ;-) */
312 * This is how a function handling a Wireless Extension should look
313 * like (both get and set, standard and private).
315 typedef int (*iw_handler
)(struct net_device
*dev
, struct iw_request_info
*info
,
316 union iwreq_data
*wrqu
, char *extra
);
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>
324 struct iw_handler_def
326 /* Number of handlers defined (more precisely, index of the
327 * last defined handler + 1) */
330 /* Number of private arg description */
331 __u16 num_private_args
;
333 /* Array of handlers for standard ioctls
334 * We will call dev->wireless_handlers->standard[ioctl - SIOCSIWCOMMIT]
336 const iw_handler
* standard
;
338 /* Array of handlers for private ioctls
339 * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
341 const iw_handler
* private;
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
;
348 /* New location of get_wireless_stats, to de-bloat struct net_device.
349 * The old pointer in struct net_device will be gradually phased
350 * out, and drivers are encouraged to use this one... */
351 struct iw_statistics
* (*get_wireless_stats
)(struct net_device
*dev
);
354 /* ---------------------- IOCTL DESCRIPTION ---------------------- */
356 * One of the main goal of the new interface is to deal entirely with
357 * user space/kernel space memory move.
358 * For that, we need to know :
359 * o if iwreq is a pointer or contain the full data
360 * o what is the size of the data to copy
362 * For private IOCTLs, we use the same rules as used by iwpriv and
363 * defined in struct iw_priv_args.
365 * For standard IOCTLs, things are quite different and we need to
366 * use the stuctures below. Actually, this struct is also more
367 * efficient, but that's another story...
371 * Describe how a standard IOCTL looks like.
373 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 */
383 /* Need to think of short header translation table. Later. */
385 /* --------------------- ENHANCED SPY SUPPORT --------------------- */
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.
394 * Instance specific spy data, i.e. addresses spied and quality for them.
398 /* --- Standard spy support --- */
400 u_char spy_address
[IW_MAX_SPY
][ETH_ALEN
];
401 struct iw_quality spy_stat
[IW_MAX_SPY
];
402 /* --- Enhanced spy support (event) */
403 struct iw_quality spy_thr_low
; /* Low threshold */
404 struct iw_quality spy_thr_high
; /* High threshold */
405 u_char spy_thr_under
[IW_MAX_SPY
];
408 /* --------------------- DEVICE WIRELESS DATA --------------------- */
410 * This is all the wireless data specific to a device instance that
411 * is managed by the core of Wireless Extensions or the 802.11 layer.
412 * We only keep pointer to those structures, so that a driver is free
413 * to share them between instances.
414 * This structure should be initialised before registering the device.
415 * Access to this data follow the same rules as any other struct net_device
416 * data (i.e. valid as long as struct net_device exist, same locking rules).
418 /* Forward declaration */
419 struct ieee80211_device
;
421 struct iw_public_data
{
422 /* Driver enhanced spy support */
423 struct iw_spy_data
* spy_data
;
424 /* Structure managed by the in-kernel IEEE 802.11 layer */
425 struct ieee80211_device
* ieee80211
;
428 /**************************** PROTOTYPES ****************************/
430 * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
431 * Those may be called only within the kernel.
434 /* First : function strictly used inside the kernel */
436 /* Handle /proc/net/wireless, called in net/code/dev.c */
437 extern int dev_get_wireless_info(char * buffer
, char **start
, off_t offset
,
440 /* Second : functions that may be called by driver modules */
442 /* Send a single event to user space */
443 extern void wireless_send_event(struct net_device
* dev
,
445 union iwreq_data
* wrqu
,
448 /* We may need a function to send a stream of events to user space.
449 * More on that later... */
451 /* Standard handler for SIOCSIWSPY */
452 extern int iw_handler_set_spy(struct net_device
* dev
,
453 struct iw_request_info
* info
,
454 union iwreq_data
* wrqu
,
456 /* Standard handler for SIOCGIWSPY */
457 extern int iw_handler_get_spy(struct net_device
* dev
,
458 struct iw_request_info
* info
,
459 union iwreq_data
* wrqu
,
461 /* Standard handler for SIOCSIWTHRSPY */
462 extern int iw_handler_set_thrspy(struct net_device
* dev
,
463 struct iw_request_info
*info
,
464 union iwreq_data
* wrqu
,
466 /* Standard handler for SIOCGIWTHRSPY */
467 extern int iw_handler_get_thrspy(struct net_device
* dev
,
468 struct iw_request_info
*info
,
469 union iwreq_data
* wrqu
,
471 /* Driver call to update spy records */
472 extern void wireless_spy_update(struct net_device
* dev
,
473 unsigned char * address
,
474 struct iw_quality
* wstats
);
476 /************************* INLINE FUNTIONS *************************/
478 * Function that are so simple that it's more efficient inlining them
481 static inline int iwe_stream_lcp_len(struct iw_request_info
*info
)
484 if (info
->flags
& IW_REQUEST_FLAG_COMPAT
)
485 return IW_EV_COMPAT_LCP_LEN
;
487 return IW_EV_LCP_LEN
;
490 static inline int iwe_stream_point_len(struct iw_request_info
*info
)
493 if (info
->flags
& IW_REQUEST_FLAG_COMPAT
)
494 return IW_EV_COMPAT_POINT_LEN
;
496 return IW_EV_POINT_LEN
;
499 static inline int iwe_stream_event_len_adjust(struct iw_request_info
*info
,
503 if (info
->flags
& IW_REQUEST_FLAG_COMPAT
) {
504 event_len
-= IW_EV_LCP_LEN
;
505 event_len
+= IW_EV_COMPAT_LCP_LEN
;
512 /*------------------------------------------------------------------*/
514 * Wrapper to add an Wireless Event to a stream of events.
517 iwe_stream_add_event(struct iw_request_info
*info
, char *stream
, char *ends
,
518 struct iw_event
*iwe
, int event_len
)
520 int lcp_len
= iwe_stream_lcp_len(info
);
522 event_len
= iwe_stream_event_len_adjust(info
, event_len
);
524 /* Check if it's possible */
525 if(likely((stream
+ event_len
) < ends
)) {
526 iwe
->len
= event_len
;
527 /* Beware of alignement issues on 64 bits */
528 memcpy(stream
, (char *) iwe
, IW_EV_LCP_PK_LEN
);
529 memcpy(stream
+ lcp_len
, &iwe
->u
,
530 event_len
- lcp_len
);
536 /*------------------------------------------------------------------*/
538 * Wrapper to add an short Wireless Event containing a pointer to a
542 iwe_stream_add_point(struct iw_request_info
*info
, char *stream
, char *ends
,
543 struct iw_event
*iwe
, char *extra
)
545 int event_len
= iwe_stream_point_len(info
) + iwe
->u
.data
.length
;
546 int point_len
= iwe_stream_point_len(info
);
547 int lcp_len
= iwe_stream_lcp_len(info
);
549 /* Check if it's possible */
550 if(likely((stream
+ event_len
) < ends
)) {
551 iwe
->len
= event_len
;
552 memcpy(stream
, (char *) iwe
, IW_EV_LCP_PK_LEN
);
553 memcpy(stream
+ lcp_len
,
554 ((char *) &iwe
->u
) + IW_EV_POINT_OFF
,
555 IW_EV_POINT_PK_LEN
- IW_EV_LCP_PK_LEN
);
556 memcpy(stream
+ point_len
, extra
, iwe
->u
.data
.length
);
562 /*------------------------------------------------------------------*/
564 * Wrapper to add a value to a Wireless Event in a stream of events.
565 * Be careful, this one is tricky to use properly :
566 * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
569 iwe_stream_add_value(struct iw_request_info
*info
, char *event
, char *value
,
570 char *ends
, struct iw_event
*iwe
, int event_len
)
572 int lcp_len
= iwe_stream_lcp_len(info
);
574 /* Don't duplicate LCP */
575 event_len
-= IW_EV_LCP_LEN
;
577 /* Check if it's possible */
578 if(likely((value
+ event_len
) < ends
)) {
580 memcpy(value
, &iwe
->u
, event_len
);
583 iwe
->len
= value
- event
;
584 memcpy(event
, (char *) iwe
, lcp_len
);
589 #endif /* _IW_HANDLER_H */