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 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 */ 473 474 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 } 482 483 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 } 491 492 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 * 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 * 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