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/* SPDX-License-Identifier: GPL-2.0 / / * This file define the new driver API for Wireless Extensions * * Version : 8 16.3.07 * * Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com> * Copyright (c) 2001-2007 Jean Tourrilhes, All Rights Reserved. / #ifndef _IW_HANDLER_H #define _IW_HANDLER_H /*********************** DOCUMENTATION ***********************/ / * Initial driver API (1996 -> onward) : * ----------------------------------- * The initial API just sends the IOCTL request received from user space * to the driver (via the driver ioctl handler). The driver has to * handle all the rest... * * The initial API also defines a specific handler in struct net_device * to handle wireless statistics. * * The initial APIs served us well and has proven a reasonably good design. * However, there is a few shortcommings : * o No events, everything is a request to the driver. * o Large ioctl function in driver with gigantic switch statement * (i.e. spaghetti code). * o Driver has to mess up with copy_to/from_user, and in many cases * does it unproperly. Common mistakes are : * * buffer overflows (no checks or off by one checks) * * call copy_to/from_user with irq disabled * o The user space interface is tied to ioctl because of the use * copy_to/from_user. * * New driver API (2002 -> onward) : * ------------------------------- * The new driver API is just a bunch of standard functions (handlers), * each handling a specific Wireless Extension. The driver just export * the list of handler it supports, and those will be called apropriately. * * I tried to keep the main advantage of the previous API (simplicity, * efficiency and light weight), and also I provide a good dose of backward * compatibility (most structures are the same, driver can use both API * simultaneously, ...). * Hopefully, I've also addressed the shortcomming of the initial API. * * The advantage of the new API are : * o Handling of Extensions in driver broken in small contained functions * o Tighter checks of ioctl before calling the driver * o Flexible commit strategy (at least, the start of it) * o Backward compatibility (can be mixed with old API) * o Driver doesn't have to worry about memory and user-space issues * The last point is important for the following reasons : * o You are now able to call the new driver API from any API you * want (including from within other parts of the kernel). * o Common mistakes are avoided (buffer overflow, user space copy * with irq disabled and so on). * * The Drawback of the new API are : * o bloat (especially kernel) * o need to migrate existing drivers to new API * My initial testing shows that the new API adds around 3kB to the kernel * and save between 0 and 5kB from a typical driver. * Also, as all structures and data types are unchanged, the migration is * quite straightforward (but tedious). * * --- * * The new driver API is defined below in this file. User space should * not be aware of what's happening down there... * * A new kernel wrapper is in charge of validating the IOCTLs and calling * the appropriate driver handler. This is implemented in : * # net/core/wireless.c * * The driver export the list of handlers in : * # include/linux/netdevice.h (one place) * * The new driver API is available for WIRELESS_EXT >= 13. * Good luck with migration to the new API ;-) / / ---------------------- THE IMPLEMENTATION ---------------------- / / * Some of the choice I've made are pretty controversials. Defining an * API is very much weighting compromises. This goes into some of the * details and the thinking behind the implementation. * * Implementation goals : * -------------------- * The implementation goals were as follow : * o Obvious : you should not need a PhD to understand what's happening, * the benefit is easier maintenance. * o Flexible : it should accommodate a wide variety of driver * implementations and be as flexible as the old API. * o Lean : it should be efficient memory wise to minimise the impact * on kernel footprint. * o Transparent to user space : the large number of user space * applications that use Wireless Extensions should not need * any modifications. * * Array of functions versus Struct of functions * --------------------------------------------- * 1) Having an array of functions allow the kernel code to access the * handler in a single lookup, which is much more efficient (think hash * table here). * 2) The only drawback is that driver writer may put their handler in * the wrong slot. This is trivial to test (I set the frequency, the * bitrate changes). Once the handler is in the proper slot, it will be * there forever, because the array is only extended at the end. * 3) Backward/forward compatibility : adding new handler just require * extending the array, so you can put newer driver in older kernel * without having to patch the kernel code (and vice versa). * * All handler are of the same generic type * ---------------------------------------- * That's a feature !!! * 1) Having a generic handler allow to have generic code, which is more * efficient. If each of the handler was individually typed I would need * to add a big switch in the kernel (== more bloat). This solution is * more scalable, adding new Wireless Extensions doesn't add new code. * 2) You can use the same handler in different slots of the array. For * hardware, it may be more efficient or logical to handle multiple * Wireless Extensions with a single function, and the API allow you to * do that. (An example would be a single record on the card to control * both bitrate and frequency, the handler would read the old record, * modify it according to info->cmd and rewrite it). * * Functions prototype uses union iwreq_data * ----------------------------------------- * Some would have preferred functions defined this way : * static int mydriver_ioctl_setrate(struct net_device dev, long rate, int auto) * 1) The kernel code doesn't "validate" the content of iwreq_data, and * can't do it (different hardware may have different notion of what a * valid frequency is), so we don't pretend that we do it. * 2) The above form is not extendable. If I want to add a flag (for * example to distinguish setting max rate and basic rate), I would * break the prototype. Using iwreq_data is more flexible. * 3) Also, the above form is not generic (see above). * 4) I don't expect driver developper using the wrong field of the * union (Doh !), so static typechecking doesn't add much value. * 5) Lastly, you can skip the union by doing : * static int mydriver_ioctl_setrate(struct net_device dev, struct iw_request_info info, struct iw_param rrq, char extra) And then adding the handler in the array like this : * (iw_handler) mydriver_ioctl_setrate, // SIOCSIWRATE * * Using functions and not a registry * ---------------------------------- * Another implementation option would have been for every instance to * define a registry (a struct containing all the Wireless Extensions) * and only have a function to commit the registry to the hardware. * 1) This approach can be emulated by the current code, but not * vice versa. * 2) Some drivers don't keep any configuration in the driver, for them * adding such a registry would be a significant bloat. * 3) The code to translate from Wireless Extension to native format is * needed anyway, so it would not reduce significantely the amount of code. * 4) The current approach only selectively translate Wireless Extensions * to native format and only selectively set, whereas the registry approach * would require to translate all WE and set all parameters for any single * change. * 5) For many Wireless Extensions, the GET operation return the current * dynamic value, not the value that was set. * * This header is <net/iw_handler.h> * --------------------------------- * 1) This header is kernel space only and should not be exported to * user space. Headers in "include/linux/" are exported, headers in * "include/net/" are not. * * Mixed 32/64 bit issues * ---------------------- * The Wireless Extensions are designed to be 64 bit clean, by using only * datatypes with explicit storage size. * There are some issues related to kernel and user space using different * memory model, and in particular 64bit kernel with 32bit user space. * The problem is related to struct iw_point, that contains a pointer * that may need to be translated. * This is quite messy. The new API doesn't solve this problem (it can't), * but is a step in the right direction : * 1) Meta data about each ioctl is easily available, so we know what type * of translation is needed. * 2) The move of data between kernel and user space is only done in a single * place in the kernel, so adding specific hooks in there is possible. * 3) In the long term, it allows to move away from using ioctl as the * user space API. * * So many comments and so few code * -------------------------------- * That's a feature. Comments won't bloat the resulting kernel binary. / /************************** INCLUDES **************************/ #include <linux/wireless.h> / IOCTL user space API / #include <linux/if_ether.h> /************************** VERSION **************************/ / * This constant is used to know which version of the driver API is * available. Hopefully, this will be pretty stable and no changes * will be needed... * I just plan to increment with each new version. / #define IW_HANDLER_VERSION 8 / * Changes : * * V2 to V3 * -------- * - Move event definition in <linux/wireless.h> * - Add Wireless Event support : * o wireless_send_event() prototype * o iwe_stream_add_event/point() inline functions * V3 to V4 * -------- * - Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes * * V4 to V5 * -------- * - Add new spy support : struct iw_spy_data & prototypes * * V5 to V6 * -------- * - Change the way we get to spy_data method for added safety * - Remove spy #ifdef, they are always on -> cleaner code * - Add IW_DESCR_FLAG_NOMAX flag for very large requests * - Start migrating get_wireless_stats to struct iw_handler_def * * V6 to V7 * -------- * - Add struct ieee80211_device pointer in struct iw_public_data * - Remove (struct iw_point )->pointer from events and streams - Remove spy_offset from struct iw_handler_def * - Add "check" version of event macros for ieee802.11 stack * * V7 to V8 * ---------- * - Prevent leaking of kernel space in stream on 64 bits. / /************************* CONSTANTS *************************/ / Enhanced spy support available / #define IW_WIRELESS_SPY #define IW_WIRELESS_THRSPY / Special error message for the driver to indicate that we * should do a commit after return from the iw_handler / #define EIWCOMMIT EINPROGRESS / Flags available in struct iw_request_info / #define IW_REQUEST_FLAG_COMPAT 0x0001 / Compat ioctl call / / Type of headers we know about (basically union iwreq_data) / #define IW_HEADER_TYPE_NULL 0 / Not available / #define IW_HEADER_TYPE_CHAR 2 / char [IFNAMSIZ] / #define IW_HEADER_TYPE_UINT 4 / __u32 / #define IW_HEADER_TYPE_FREQ 5 / struct iw_freq / #define IW_HEADER_TYPE_ADDR 6 / struct sockaddr / #define IW_HEADER_TYPE_POINT 8 / struct iw_point / #define IW_HEADER_TYPE_PARAM 9 / struct iw_param / #define IW_HEADER_TYPE_QUAL 10 / struct iw_quality / / Handling flags / / Most are not implemented. I just use them as a reminder of some * cool features we might need one day ;-) / #define IW_DESCR_FLAG_NONE 0x0000 / Obvious / / Wrapper level flags / #define IW_DESCR_FLAG_DUMP 0x0001 / Not part of the dump command / #define IW_DESCR_FLAG_EVENT 0x0002 / Generate an event on SET / #define IW_DESCR_FLAG_RESTRICT 0x0004 / GET : request is ROOT only / / SET : Omit payload from generated iwevent / #define IW_DESCR_FLAG_NOMAX 0x0008 / GET : no limit on request size / / Driver level flags / #define IW_DESCR_FLAG_WAIT 0x0100 / Wait for driver event / /*************************** TYPES ***************************/ / ----------------------- WIRELESS HANDLER ----------------------- / / * A wireless handler is just a standard function, that looks like the * ioctl handler. * We also define there how a handler list look like... As the Wireless * Extension space is quite dense, we use a simple array, which is faster * (that's the perfect hash table ;-). / / * Meta data about the request passed to the iw_handler. * Most handlers can safely ignore what's in there. * The 'cmd' field might come handy if you want to use the same handler * for multiple command... * This struct is also my long term insurance. I can add new fields here * without breaking the prototype of iw_handler... / struct iw_request_info { __u16 cmd; / Wireless Extension command / __u16 flags; / More to come ;-) / }; struct net_device; / * This is how a function handling a Wireless Extension should look * like (both get and set, standard and private). / typedef int (iw_handler)(struct net_device dev, struct iw_request_info info, union iwreq_data wrqu, char extra); /* * This define all the handler that the driver export. * As you need only one per driver type, please use a static const * shared by all driver instances... Same for the members... * This will be linked from net_device in <linux/netdevice.h> / struct iw_handler_def { / Array of handlers for standard ioctls * We will call dev->wireless_handlers->standard[ioctl - SIOCIWFIRST] / const iw_handler standard; /* Number of handlers defined (more precisely, index of the * last defined handler + 1) / __u16 num_standard; #ifdef CONFIG_WEXT_PRIV __u16 num_private; / Number of private arg description / __u16 num_private_args; / Array of handlers for private ioctls * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV] / const iw_handler private; /* Arguments of private handler. This one is just a list, so you * can put it in any order you want and should not leave holes... * We will automatically export that to user space... / const struct iw_priv_args private_args; #endif /* New location of get_wireless_stats, to de-bloat struct net_device. * The old pointer in struct net_device will be gradually phased * out, and drivers are encouraged to use this one... / struct iw_statistics (get_wireless_stats)(struct net_device dev); }; /* ---------------------- IOCTL DESCRIPTION ---------------------- / / * One of the main goal of the new interface is to deal entirely with * user space/kernel space memory move. * For that, we need to know : * o if iwreq is a pointer or contain the full data * o what is the size of the data to copy * * For private IOCTLs, we use the same rules as used by iwpriv and * defined in struct iw_priv_args. * * For standard IOCTLs, things are quite different and we need to * use the structures below. Actually, this struct is also more * efficient, but that's another story... / / * Describe how a standard IOCTL looks like. / struct iw_ioctl_description { __u8 header_type; / NULL, iw_point or other / __u8 token_type; / Future / __u16 token_size; / Granularity of payload / __u16 min_tokens; / Min acceptable token number / __u16 max_tokens; / Max acceptable token number / __u32 flags; / Special handling of the request / }; / Need to think of short header translation table. Later. / / --------------------- ENHANCED SPY SUPPORT --------------------- / / * In the old days, the driver was handling spy support all by itself. * Now, the driver can delegate this task to Wireless Extensions. * It needs to include this struct in its private part and use the * standard spy iw_handler. / / * Instance specific spy data, i.e. addresses spied and quality for them. / struct iw_spy_data { / --- Standard spy support --- / int spy_number; u_char spy_address[IW_MAX_SPY][ETH_ALEN]; struct iw_quality spy_stat[IW_MAX_SPY]; / --- Enhanced spy support (event) / struct iw_quality spy_thr_low; / Low threshold / struct iw_quality spy_thr_high; / High threshold / u_char spy_thr_under[IW_MAX_SPY]; }; / --------------------- DEVICE WIRELESS DATA --------------------- / / * This is all the wireless data specific to a device instance that * is managed by the core of Wireless Extensions or the 802.11 layer. * We only keep pointer to those structures, so that a driver is free * to share them between instances. * This structure should be initialised before registering the device. * Access to this data follow the same rules as any other struct net_device * data (i.e. valid as long as struct net_device exist, same locking rules). / / Forward declaration / struct libipw_device; / The struct / struct iw_public_data { / Driver enhanced spy support / struct iw_spy_data spy_data; /* Legacy structure managed by the ipw2x00-specific IEEE 802.11 layer / struct libipw_device libipw; }; /************************** PROTOTYPES *************************/ / * Functions part of the Wireless Extensions (defined in net/core/wireless.c). * Those may be called only within the kernel. / / First : function strictly used inside the kernel / / Handle /proc/net/wireless, called in net/code/dev.c / int dev_get_wireless_info(char buffer, char *start, off_t offset, int length); / Second : functions that may be called by driver modules / / Send a single event to user space / void wireless_send_event(struct net_device dev, unsigned int cmd, union iwreq_data wrqu, const char extra); #ifdef CONFIG_WEXT_CORE /* flush all previous wext events - if work is done from netdev notifiers / void wireless_nlevent_flush(void); #else static inline void wireless_nlevent_flush(void) {} #endif / We may need a function to send a stream of events to user space. * More on that later... / / Standard handler for SIOCSIWSPY / int iw_handler_set_spy(struct net_device dev, struct iw_request_info info, union iwreq_data wrqu, char extra); / Standard handler for SIOCGIWSPY / int iw_handler_get_spy(struct net_device dev, struct iw_request_info info, union iwreq_data wrqu, char extra); / Standard handler for SIOCSIWTHRSPY / int iw_handler_set_thrspy(struct net_device dev, struct iw_request_info info, union iwreq_data wrqu, char extra); / Standard handler for SIOCGIWTHRSPY / int iw_handler_get_thrspy(struct net_device dev, struct iw_request_info info, union iwreq_data wrqu, char extra); / Driver call to update spy records / void wireless_spy_update(struct net_device dev, unsigned char address, struct iw_quality wstats); /*********************** INLINE FUNTIONS **********************/ / * Function that are so simple that it's more efficient inlining them / static inline int iwe_stream_lcp_len(struct iw_request_info info) { #ifdef CONFIG_COMPAT if (info->flags & IW_REQUEST_FLAG_COMPAT) return IW_EV_COMPAT_LCP_LEN; #endif return IW_EV_LCP_LEN; } static inline int iwe_stream_point_len(struct iw_request_info info) { #ifdef CONFIG_COMPAT if (info->flags & IW_REQUEST_FLAG_COMPAT) return IW_EV_COMPAT_POINT_LEN; #endif return IW_EV_POINT_LEN; } static inline int iwe_stream_event_len_adjust(struct iw_request_info info, int event_len) { #ifdef CONFIG_COMPAT if (info->flags & IW_REQUEST_FLAG_COMPAT) { event_len -= IW_EV_LCP_LEN; event_len += IW_EV_COMPAT_LCP_LEN; } #endif return event_len; } /------------------------------------------------------------------/ /* * Wrapper to add an Wireless Event to a stream of events. / char iwe_stream_add_event(struct iw_request_info info, char stream, char ends, struct iw_event iwe, int event_len); static inline char * iwe_stream_add_event_check(struct iw_request_info info, char stream, char ends, struct iw_event iwe, int event_len) { char res = iwe_stream_add_event(info, stream, ends, iwe, event_len); if (res == stream) return ERR_PTR(-E2BIG); return res; } /------------------------------------------------------------------/ / * Wrapper to add an short Wireless Event containing a pointer to a * stream of events. / char iwe_stream_add_point(struct iw_request_info info, char stream, char ends, struct iw_event iwe, char extra); static inline char iwe_stream_add_point_check(struct iw_request_info info, char stream, char ends, struct iw_event iwe, char extra) { char res = iwe_stream_add_point(info, stream, ends, iwe, extra); if (res == stream) return ERR_PTR(-E2BIG); return res; } /------------------------------------------------------------------/ /* * Wrapper to add a value to a Wireless Event in a stream of events. * Be careful, this one is tricky to use properly : * At the first run, you need to have (value = event + IW_EV_LCP_LEN). / char iwe_stream_add_value(struct iw_request_info info, char event, char value, char ends, struct iw_event iwe, int event_len); #endif / _IW_HANDLER_H */

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