include/net/iw_handler.h

   1 /*
   2  * This file define the new driver API for Wireless Extensions
   3  *
   4  * Version :    5       4.12.02
   5  *
   6  * Authors :    Jean Tourrilhes - HPL - <jt@hpl.hp.com>
   7  * Copyright (c) 2001-2002 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
 202 /***************************** VERSION *****************************/
 203 /*
 204  * This constant is used to know which version of the driver API is
 205  * available. Hopefully, this will be pretty stable and no changes
 206  * will be needed...
 207  * I just plan to increment with each new version.
 208  */
 209 #define IW_HANDLER_VERSION      5
 210
 211 /*
 212  * Changes :
 213  *
 214  * V2 to V3
 215  * --------
 216  *      - Move event definition in <linux/wireless.h>
 217  *      - Add Wireless Event support :
 218  *              o wireless_send_event() prototype
 219  *              o iwe_stream_add_event/point() inline functions
 220  * V3 to V4
 221  * --------
 222  *      - Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
 223  *
 224  * V4 to V5
 225  * --------
 226  *      - Add new spy support : struct iw_spy_data & prototypes
 227  */
 228
 229 /**************************** CONSTANTS ****************************/
 230
 231 /* Enable enhanced spy support. Disable to reduce footprint */
 232 #define IW_WIRELESS_SPY
 233 #define IW_WIRELESS_THRSPY
 234
 235 /* Special error message for the driver to indicate that we
 236  * should do a commit after return from the iw_handler */
 237 #define EIWCOMMIT       EINPROGRESS
 238
 239 /* Flags available in struct iw_request_info */
 240 #define IW_REQUEST_FLAG_NONE    0x0000  /* No flag so far */
 241
 242 /* Type of headers we know about (basically union iwreq_data) */
 243 #define IW_HEADER_TYPE_NULL     0       /* Not available */
 244 #define IW_HEADER_TYPE_CHAR     2       /* char [IFNAMSIZ] */
 245 #define IW_HEADER_TYPE_UINT     4       /* __u32 */
 246 #define IW_HEADER_TYPE_FREQ     5       /* struct iw_freq */
 247 #define IW_HEADER_TYPE_ADDR     6       /* struct sockaddr */
 248 #define IW_HEADER_TYPE_POINT    8       /* struct iw_point */
 249 #define IW_HEADER_TYPE_PARAM    9       /* struct iw_param */
 250 #define IW_HEADER_TYPE_QUAL     10      /* struct iw_quality */
 251
 252 /* Handling flags */
 253 /* Most are not implemented. I just use them as a reminder of some
 254  * cool features we might need one day ;-) */
 255 #define IW_DESCR_FLAG_NONE      0x0000  /* Obvious */
 256 /* Wrapper level flags */
 257 #define IW_DESCR_FLAG_DUMP      0x0001  /* Not part of the dump command */
 258 #define IW_DESCR_FLAG_EVENT     0x0002  /* Generate an event on SET */
 259 #define IW_DESCR_FLAG_RESTRICT  0x0004  /* GET : request is ROOT only */
 260                                 /* SET : Omit payload from generated iwevent */
 261 /* Driver level flags */
 262 #define IW_DESCR_FLAG_WAIT      0x0100  /* Wait for driver event */
 263
 264 /****************************** TYPES ******************************/
 265
 266 /* ----------------------- WIRELESS HANDLER ----------------------- */
 267 /*
 268  * A wireless handler is just a standard function, that looks like the
 269  * ioctl handler.
 270  * We also define there how a handler list look like... As the Wireless
 271  * Extension space is quite dense, we use a simple array, which is faster
 272  * (that's the perfect hash table ;-).
 273  */
 274
 275 /*
 276  * Meta data about the request passed to the iw_handler.
 277  * Most handlers can safely ignore what's in there.
 278  * The 'cmd' field might come handy if you want to use the same handler
 279  * for multiple command...
 280  * This struct is also my long term insurance. I can add new fields here
 281  * without breaking the prototype of iw_handler...
 282  */
 283 struct iw_request_info
 284 {
 285         __u16           cmd;            /* Wireless Extension command */
 286         __u16           flags;          /* More to come ;-) */
 287 };
 288
 289 /*
 290  * This is how a function handling a Wireless Extension should look
 291  * like (both get and set, standard and private).
 292  */
 293 typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info,
 294                           union iwreq_data *wrqu, char *extra);
 295
 296 /*
 297  * This define all the handler that the driver export.
 298  * As you need only one per driver type, please use a static const
 299  * shared by all driver instances... Same for the members...
 300  * This will be linked from net_device in <linux/netdevice.h>
 301  */
 302 struct iw_handler_def
 303 {
 304         /* Number of handlers defined (more precisely, index of the
 305          * last defined handler + 1) */
 306         __u16                   num_standard;
 307         __u16                   num_private;
 308         /* Number of private arg description */
 309         __u16                   num_private_args;
 310
 311         /* Array of handlers for standard ioctls
 312          * We will call dev->wireless_handlers->standard[ioctl - SIOCSIWNAME]
 313          */
 314         iw_handler *            standard;
 315
 316         /* Array of handlers for private ioctls
 317          * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
 318          */
 319         iw_handler *            private;
 320
 321         /* Arguments of private handler. This one is just a list, so you
 322          * can put it in any order you want and should not leave holes...
 323          * We will automatically export that to user space... */
 324         struct iw_priv_args *   private_args;
 325
 326         /* Driver enhanced spy support */
 327         long                    spy_offset;     /* Spy data offset */
 328
 329         /* In the long term, get_wireless_stats will move from
 330          * 'struct net_device' to here, to minimise bloat. */
 331 };
 332
 333 /* ---------------------- IOCTL DESCRIPTION ---------------------- */
 334 /*
 335  * One of the main goal of the new interface is to deal entirely with
 336  * user space/kernel space memory move.
 337  * For that, we need to know :
 338  *      o if iwreq is a pointer or contain the full data
 339  *      o what is the size of the data to copy
 340  *
 341  * For private IOCTLs, we use the same rules as used by iwpriv and
 342  * defined in struct iw_priv_args.
 343  *
 344  * For standard IOCTLs, things are quite different and we need to
 345  * use the stuctures below. Actually, this struct is also more
 346  * efficient, but that's another story...
 347  */
 348
 349 /*
 350  * Describe how a standard IOCTL looks like.
 351  */
 352 struct iw_ioctl_description
 353 {
 354         __u8    header_type;            /* NULL, iw_point or other */
 355         __u8    token_type;             /* Future */
 356         __u16   token_size;             /* Granularity of payload */
 357         __u16   min_tokens;             /* Min acceptable token number */
 358         __u16   max_tokens;             /* Max acceptable token number */
 359         __u32   flags;                  /* Special handling of the request */
 360 };
 361
 362 /* Need to think of short header translation table. Later. */
 363
 364 /* --------------------- ENHANCED SPY SUPPORT --------------------- */
 365 /*
 366  * In the old days, the driver was handling spy support all by itself.
 367  * Now, the driver can delegate this task to Wireless Extensions.
 368  * It needs to include this struct in its private part and use the
 369  * standard spy iw_handler.
 370  */
 371
 372 /*
 373  * Instance specific spy data, i.e. addresses spied and quality for them.
 374  */
 375 struct iw_spy_data
 376 {
 377 #ifdef IW_WIRELESS_SPY
 378         /* --- Standard spy support --- */
 379         int                     spy_number;
 380         u_char                  spy_address[IW_MAX_SPY][ETH_ALEN];
 381         struct iw_quality       spy_stat[IW_MAX_SPY];
 382 #ifdef IW_WIRELESS_THRSPY
 383         /* --- Enhanced spy support (event) */
 384         struct iw_quality       spy_thr_low;    /* Low threshold */
 385         struct iw_quality       spy_thr_high;   /* High threshold */
 386         u_char                  spy_thr_under[IW_MAX_SPY];
 387 #endif /* IW_WIRELESS_THRSPY */
 388 #endif /* IW_WIRELESS_SPY */
 389 };
 390
 391 /**************************** PROTOTYPES ****************************/
 392 /*
 393  * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
 394  * Those may be called only within the kernel.
 395  */
 396
 397 /* First : function strictly used inside the kernel */
 398
 399 /* Handle /proc/net/wireless, called in net/code/dev.c */
 400 extern int dev_get_wireless_info(char * buffer, char **start, off_t offset,
 401                                  int length);
 402
 403 /* Handle IOCTLs, called in net/code/dev.c */
 404 extern int wireless_process_ioctl(struct ifreq *ifr, unsigned int cmd);
 405
 406 /* Second : functions that may be called by driver modules */
 407
 408 /* Send a single event to user space */
 409 extern void wireless_send_event(struct net_device *     dev,
 410                                 unsigned int            cmd,
 411                                 union iwreq_data *      wrqu,
 412                                 char *                  extra);
 413
 414 /* We may need a function to send a stream of events to user space.
 415  * More on that later... */
 416
 417 /* Standard handler for SIOCSIWSPY */
 418 extern int iw_handler_set_spy(struct net_device *       dev,
 419                               struct iw_request_info *  info,
 420                               union iwreq_data *        wrqu,
 421                               char *                    extra);
 422 /* Standard handler for SIOCGIWSPY */
 423 extern int iw_handler_get_spy(struct net_device *       dev,
 424                               struct iw_request_info *  info,
 425                               union iwreq_data *        wrqu,
 426                               char *                    extra);
 427 /* Standard handler for SIOCSIWTHRSPY */
 428 extern int iw_handler_set_thrspy(struct net_device *    dev,
 429                                  struct iw_request_info *info,
 430                                  union iwreq_data *     wrqu,
 431                                  char *                 extra);
 432 /* Standard handler for SIOCGIWTHRSPY */
 433 extern int iw_handler_get_thrspy(struct net_device *    dev,
 434                                  struct iw_request_info *info,
 435                                  union iwreq_data *     wrqu,
 436                                  char *                 extra);
 437 /* Driver call to update spy records */
 438 extern void wireless_spy_update(struct net_device *     dev,
 439                                 unsigned char *         address,
 440                                 struct iw_quality *     wstats);
 441
 442 /************************* INLINE FUNTIONS *************************/
 443 /*
 444  * Function that are so simple that it's more efficient inlining them
 445  */
 446
 447 /*------------------------------------------------------------------*/
 448 /*
 449  * Wrapper to add an Wireless Event to a stream of events.
 450  */
 451 static inline char *
 452 iwe_stream_add_event(char *     stream,         /* Stream of events */
 453                      char *     ends,           /* End of stream */
 454                      struct iw_event *iwe,      /* Payload */
 455                      int        event_len)      /* Real size of payload */
 456 {
 457         /* Check if it's possible */
 458         if((stream + event_len) < ends) {
 459                 iwe->len = event_len;
 460                 memcpy(stream, (char *) iwe, event_len);
 461                 stream += event_len;
 462         }
 463         return stream;
 464 }
 465
 466 /*------------------------------------------------------------------*/
 467 /*
 468  * Wrapper to add an short Wireless Event containing a pointer to a
 469  * stream of events.
 470  */
 471 static inline char *
 472 iwe_stream_add_point(char *     stream,         /* Stream of events */
 473                      char *     ends,           /* End of stream */
 474                      struct iw_event *iwe,      /* Payload */
 475                      char *     extra)
 476 {
 477         int     event_len = IW_EV_POINT_LEN + iwe->u.data.length;
 478         /* Check if it's possible */
 479         if((stream + event_len) < ends) {
 480                 iwe->len = event_len;
 481                 memcpy(stream, (char *) iwe, IW_EV_POINT_LEN);
 482                 memcpy(stream + IW_EV_POINT_LEN, extra, iwe->u.data.length);
 483                 stream += event_len;
 484         }
 485         return stream;
 486 }
 487
 488 /*------------------------------------------------------------------*/
 489 /*
 490  * Wrapper to add a value to a Wireless Event in a stream of events.
 491  * Be careful, this one is tricky to use properly :
 492  * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
 493  */
 494 static inline char *
 495 iwe_stream_add_value(char *     event,          /* Event in the stream */
 496                      char *     value,          /* Value in event */
 497                      char *     ends,           /* End of stream */
 498                      struct iw_event *iwe,      /* Payload */
 499                      int        event_len)      /* Real size of payload */
 500 {
 501         /* Don't duplicate LCP */
 502         event_len -= IW_EV_LCP_LEN;
 503
 504         /* Check if it's possible */
 505         if((value + event_len) < ends) {
 506                 /* Add new value */
 507                 memcpy(value, (char *) iwe + IW_EV_LCP_LEN, event_len);
 508                 value += event_len;
 509                 /* Patch LCP */
 510                 iwe->len = value - event;
 511                 memcpy(event, (char *) iwe, IW_EV_LCP_LEN);
 512         }
 513         return value;
 514 }
 515
 516 #endif  /* _IW_HANDLER_H */