1 /* 2 * This file define the new driver API for Wireless Extensions 3 * 4 * Version : 8 16.3.07 5 * 6 * Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com> 7 * Copyright (c) 2001-2007 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 maintenance. 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 preferred 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 8 211 212 /* 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 * V6 to V7 237 * -------- 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 242 * 243 * V7 to V8 244 * ---------- 245 * - Prevent leaking of kernel space in stream on 64 bits. 246 */ 247 248 /**************************** CONSTANTS ****************************/ 249 250 /* Enhanced spy support available */ 251 #define IW_WIRELESS_SPY 252 #define IW_WIRELESS_THRSPY 253 254 /* 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 257 258 /* Flags available in struct iw_request_info */ 259 #define IW_REQUEST_FLAG_COMPAT 0x0001 /* Compat ioctl call */ 260 261 /* 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 */ 270 271 /* Handling flags */ 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 */ 283 284 /****************************** TYPES ******************************/ 285 286 /* ----------------------- WIRELESS HANDLER ----------------------- */ 287 /* 288 * A wireless handler is just a standard function, that looks like the 289 * ioctl handler. 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 ;-). 293 */ 294 295 /* 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... 302 */ 303 struct iw_request_info { 304 __u16 cmd; /* Wireless Extension command */ 305 __u16 flags; /* More to come ;-) */ 306 }; 307 308 struct net_device; 309 310 /* 311 * This is how a function handling a Wireless Extension should look 312 * like (both get and set, standard and private). 313 */ 314 typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info, 315 union iwreq_data *wrqu, char *extra); 316 317 /* 318 * This define all the handler that the driver export. 319 * As you need only one per driver type, please use a static const 320 * shared by all driver instances... Same for the members... 321 * This will be linked from net_device in <linux/netdevice.h> 322 */ 323 struct iw_handler_def { 324 325 /* Array of handlers for standard ioctls 326 * We will call dev->wireless_handlers->standard[ioctl - SIOCIWFIRST] 327 */ 328 const iw_handler * standard; 329 /* Number of handlers defined (more precisely, index of the 330 * last defined handler + 1) */ 331 __u16 num_standard; 332 333 #ifdef CONFIG_WEXT_PRIV 334 __u16 num_private; 335 /* Number of private arg description */ 336 __u16 num_private_args; 337 /* Array of handlers for private ioctls 338 * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV] 339 */ 340 const iw_handler * private; 341 342 /* Arguments of private handler. This one is just a list, so you 343 * can put it in any order you want and should not leave holes... 344 * We will automatically export that to user space... */ 345 const struct iw_priv_args * private_args; 346 #endif 347 348 /* 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); 352 }; 353 354 /* ---------------------- IOCTL DESCRIPTION ---------------------- */ 355 /* 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 361 * 362 * For private IOCTLs, we use the same rules as used by iwpriv and 363 * defined in struct iw_priv_args. 364 * 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... 368 */ 369 370 /* 371 * Describe how a standard IOCTL looks like. 372 */ 373 struct iw_ioctl_description { 374 __u8 header_type; /* NULL, iw_point or other */ 375 __u8 token_type; /* Future */ 376 __u16 token_size; /* Granularity of payload */ 377 __u16 min_tokens; /* Min acceptable token number */ 378 __u16 max_tokens; /* Max acceptable token number */ 379 __u32 flags; /* Special handling of the request */ 380 }; 381 382 /* Need to think of short header translation table. Later. */ 383 384 /* --------------------- ENHANCED SPY SUPPORT --------------------- */ 385 /* 386 * In the old days, the driver was handling spy support all by itself. 387 * Now, the driver can delegate this task to Wireless Extensions. 388 * It needs to include this struct in its private part and use the 389 * standard spy iw_handler. 390 */ 391 392 /* 393 * Instance specific spy data, i.e. addresses spied and quality for them. 394 */ 395 struct iw_spy_data { 396 /* --- Standard spy support --- */ 397 int spy_number; 398 u_char spy_address[IW_MAX_SPY][ETH_ALEN]; 399 struct iw_quality spy_stat[IW_MAX_SPY]; 400 /* --- Enhanced spy support (event) */ 401 struct iw_quality spy_thr_low; /* Low threshold */ 402 struct iw_quality spy_thr_high; /* High threshold */ 403 u_char spy_thr_under[IW_MAX_SPY]; 404 }; 405 406 /* --------------------- DEVICE WIRELESS DATA --------------------- */ 407 /* 408 * This is all the wireless data specific to a device instance that 409 * is managed by the core of Wireless Extensions or the 802.11 layer. 410 * We only keep pointer to those structures, so that a driver is free 411 * to share them between instances. 412 * This structure should be initialised before registering the device. 413 * Access to this data follow the same rules as any other struct net_device 414 * data (i.e. valid as long as struct net_device exist, same locking rules). 415 */ 416 /* Forward declaration */ 417 struct libipw_device; 418 /* The struct */ 419 struct iw_public_data { 420 /* Driver enhanced spy support */ 421 struct iw_spy_data * spy_data; 422 /* Legacy structure managed by the ipw2x00-specific IEEE 802.11 layer */ 423 struct libipw_device * libipw; 424 }; 425 426 /**************************** PROTOTYPES ****************************/ 427 /* 428 * Functions part of the Wireless Extensions (defined in net/core/wireless.c). 429 * Those may be called only within the kernel. 430 */ 431 432 /* First : function strictly used inside the kernel */ 433 434 /* Handle /proc/net/wireless, called in net/code/dev.c */ 435 int dev_get_wireless_info(char *buffer, char **start, off_t offset, int length); 436 437 /* Second : functions that may be called by driver modules */ 438 439 /* Send a single event to user space */ 440 void wireless_send_event(struct net_device *dev, unsigned int cmd, 441 union iwreq_data *wrqu, const char *extra); 442 #ifdef CONFIG_WEXT_CORE 443 /* flush all previous wext events - if work is done from netdev notifiers */ 444 void wireless_nlevent_flush(void); 445 #else 446 static inline void wireless_nlevent_flush(void) {} 447 #endif 448 449 /* We may need a function to send a stream of events to user space. 450 * More on that later... */ 451 452 /* Standard handler for SIOCSIWSPY */ 453 int iw_handler_set_spy(struct net_device *dev, struct iw_request_info *info, 454 union iwreq_data *wrqu, char *extra); 455 /* Standard handler for SIOCGIWSPY */ 456 int iw_handler_get_spy(struct net_device *dev, struct iw_request_info *info, 457 union iwreq_data *wrqu, char *extra); 458 /* Standard handler for SIOCSIWTHRSPY */ 459 int iw_handler_set_thrspy(struct net_device *dev, struct iw_request_info *info, 460 union iwreq_data *wrqu, char *extra); 461 /* Standard handler for SIOCGIWTHRSPY */ 462 int iw_handler_get_thrspy(struct net_device *dev, struct iw_request_info *info, 463 union iwreq_data *wrqu, char *extra); 464 /* Driver call to update spy records */ 465 void wireless_spy_update(struct net_device *dev, unsigned char *address, 466 struct iw_quality *wstats); 467 468 /************************* INLINE FUNTIONS *************************/ 469 /* 470 * Function that are so simple that it's more efficient inlining them 471 */ 472 473 static inline int iwe_stream_lcp_len(struct iw_request_info *info) 474 { 475 #ifdef CONFIG_COMPAT 476 if (info->flags & IW_REQUEST_FLAG_COMPAT) 477 return IW_EV_COMPAT_LCP_LEN; 478 #endif 479 return IW_EV_LCP_LEN; 480 } 481 482 static inline int iwe_stream_point_len(struct iw_request_info *info) 483 { 484 #ifdef CONFIG_COMPAT 485 if (info->flags & IW_REQUEST_FLAG_COMPAT) 486 return IW_EV_COMPAT_POINT_LEN; 487 #endif 488 return IW_EV_POINT_LEN; 489 } 490 491 static inline int iwe_stream_event_len_adjust(struct iw_request_info *info, 492 int event_len) 493 { 494 #ifdef CONFIG_COMPAT 495 if (info->flags & IW_REQUEST_FLAG_COMPAT) { 496 event_len -= IW_EV_LCP_LEN; 497 event_len += IW_EV_COMPAT_LCP_LEN; 498 } 499 #endif 500 501 return event_len; 502 } 503 504 /*------------------------------------------------------------------*/ 505 /* 506 * Wrapper to add an Wireless Event to a stream of events. 507 */ 508 static inline char * 509 iwe_stream_add_event(struct iw_request_info *info, char *stream, char *ends, 510 struct iw_event *iwe, int event_len) 511 { 512 int lcp_len = iwe_stream_lcp_len(info); 513 514 event_len = iwe_stream_event_len_adjust(info, event_len); 515 516 /* Check if it's possible */ 517 if(likely((stream + event_len) < ends)) { 518 iwe->len = event_len; 519 /* Beware of alignement issues on 64 bits */ 520 memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN); 521 memcpy(stream + lcp_len, &iwe->u, 522 event_len - lcp_len); 523 stream += event_len; 524 } 525 return stream; 526 } 527 528 static inline char * 529 iwe_stream_add_event_check(struct iw_request_info *info, char *stream, 530 char *ends, struct iw_event *iwe, int event_len) 531 { 532 char *res = iwe_stream_add_event(info, stream, ends, iwe, event_len); 533 534 if (res == stream) 535 return ERR_PTR(-E2BIG); 536 return res; 537 } 538 539 /*------------------------------------------------------------------*/ 540 /* 541 * Wrapper to add an short Wireless Event containing a pointer to a 542 * stream of events. 543 */ 544 static inline char * 545 iwe_stream_add_point(struct iw_request_info *info, char *stream, char *ends, 546 struct iw_event *iwe, char *extra) 547 { 548 int event_len = iwe_stream_point_len(info) + iwe->u.data.length; 549 int point_len = iwe_stream_point_len(info); 550 int lcp_len = iwe_stream_lcp_len(info); 551 552 /* Check if it's possible */ 553 if(likely((stream + event_len) < ends)) { 554 iwe->len = event_len; 555 memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN); 556 memcpy(stream + lcp_len, 557 ((char *) &iwe->u) + IW_EV_POINT_OFF, 558 IW_EV_POINT_PK_LEN - IW_EV_LCP_PK_LEN); 559 memcpy(stream + point_len, extra, iwe->u.data.length); 560 stream += event_len; 561 } 562 return stream; 563 } 564 565 static inline char * 566 iwe_stream_add_point_check(struct iw_request_info *info, char *stream, 567 char *ends, struct iw_event *iwe, char *extra) 568 { 569 char *res = iwe_stream_add_point(info, stream, ends, iwe, extra); 570 571 if (res == stream) 572 return ERR_PTR(-E2BIG); 573 return res; 574 } 575 576 /*------------------------------------------------------------------*/ 577 /* 578 * Wrapper to add a value to a Wireless Event in a stream of events. 579 * Be careful, this one is tricky to use properly : 580 * At the first run, you need to have (value = event + IW_EV_LCP_LEN). 581 */ 582 static inline char * 583 iwe_stream_add_value(struct iw_request_info *info, char *event, char *value, 584 char *ends, struct iw_event *iwe, int event_len) 585 { 586 int lcp_len = iwe_stream_lcp_len(info); 587 588 /* Don't duplicate LCP */ 589 event_len -= IW_EV_LCP_LEN; 590 591 /* Check if it's possible */ 592 if(likely((value + event_len) < ends)) { 593 /* Add new value */ 594 memcpy(value, &iwe->u, event_len); 595 value += event_len; 596 /* Patch LCP */ 597 iwe->len = value - event; 598 memcpy(event, (char *) iwe, lcp_len); 599 } 600 return value; 601 } 602 603 #endif /* _IW_HANDLER_H */ 604