/*
 * This file implement the Wireless Extensions priv API.
 *
 * Authors :    Jean Tourrilhes - HPL - <jt@hpl.hp.com>
 * Copyright (c) 1997-2007 Jean Tourrilhes, All Rights Reserved.
 * Copyright    2009 Johannes Berg <johannes@sipsolutions.net>
 *
 * (As all part of the Linux kernel, this file is GPL)
 */
#include <linux/slab.h>
#include <linux/wireless.h>
#include <linux/netdevice.h>
#include <net/iw_handler.h>
#include <net/wext.h>

int iw_handler_get_private(struct net_device *          dev,
                           struct iw_request_info *     info,
                           union iwreq_data *           wrqu,
                           char *                       extra)
{
        /* Check if the driver has something to export */
        if ((dev->wireless_handlers->num_private_args == 0) ||
           (dev->wireless_handlers->private_args == NULL))
                return -EOPNOTSUPP;

        /* Check if there is enough buffer up there */
        if (wrqu->data.length < dev->wireless_handlers->num_private_args) {
                /* User space can't know in advance how large the buffer
                 * needs to be. Give it a hint, so that we can support
                 * any size buffer we want somewhat efficiently... */
                wrqu->data.length = dev->wireless_handlers->num_private_args;
                return -E2BIG;
        }

        /* Set the number of available ioctls. */
        wrqu->data.length = dev->wireless_handlers->num_private_args;

        /* Copy structure to the user buffer. */
        memcpy(extra, dev->wireless_handlers->private_args,
               sizeof(struct iw_priv_args) * wrqu->data.length);

        return 0;
}

/* Size (in bytes) of the various private data types */
static const char iw_priv_type_size[] = {
        0,                              /* IW_PRIV_TYPE_NONE */
        1,                              /* IW_PRIV_TYPE_BYTE */
        1,                              /* IW_PRIV_TYPE_CHAR */
        0,                              /* Not defined */
        sizeof(__u32),                  /* IW_PRIV_TYPE_INT */
        sizeof(struct iw_freq),         /* IW_PRIV_TYPE_FLOAT */
        sizeof(struct sockaddr),        /* IW_PRIV_TYPE_ADDR */
        0,                              /* Not defined */
};

static int get_priv_size(__u16 args)
{
        int     num = args & IW_PRIV_SIZE_MASK;
        int     type = (args & IW_PRIV_TYPE_MASK) >> 12;

        return num * iw_priv_type_size[type];
}

static int adjust_priv_size(__u16 args, struct iw_point *iwp)
{
        int     num = iwp->length;
        int     max = args & IW_PRIV_SIZE_MASK;
        int     type = (args & IW_PRIV_TYPE_MASK) >> 12;

        /* Make sure the driver doesn't goof up */
        if (max < num)
                num = max;

        return num * iw_priv_type_size[type];
}

/*
 * Wrapper to call a private Wireless Extension handler.
 * We do various checks and also take care of moving data between
 * user space and kernel space.
 * It's not as nice and slimline as the standard wrapper. The cause
 * is struct iw_priv_args, which was not really designed for the
 * job we are going here.
 *
 * IMPORTANT : This function prevent to set and get data on the same
 * IOCTL and enforce the SET/GET convention. Not doing it would be
 * far too hairy...
 * If you need to set and get data at the same time, please don't use
 * a iw_handler but process it in your ioctl handler (i.e. use the
 * old driver API).
 */
static int get_priv_descr_and_size(struct net_device *dev, unsigned int cmd,
                                   const struct iw_priv_args **descrp)
{
        const struct iw_priv_args *descr;
        int i, extra_size;

        descr = NULL;
        for (i = 0; i < dev->wireless_handlers->num_private_args; i++) {
                if (cmd == dev->wireless_handlers->private_args[i].cmd) {
                        descr = &dev->wireless_handlers->private_args[i];
                        break;
                }
        }

        extra_size = 0;
        if (descr) {
                if (IW_IS_SET(cmd)) {
                        int     offset = 0;     /* For sub-ioctls */
                        /* Check for sub-ioctl handler */
                        if (descr->name[0] == '\0')
                                /* Reserve one int for sub-ioctl index */
                                offset = sizeof(__u32);

                        /* Size of set arguments */
                        extra_size = get_priv_size(descr->set_args);

                        /* Does it fits in iwr ? */
                        if ((descr->set_args & IW_PRIV_SIZE_FIXED) &&
                           ((extra_size + offset) <= IFNAMSIZ))
                                extra_size = 0;
                } else {
                        /* Size of get arguments */
                        extra_size = get_priv_size(descr->get_args);

                        /* Does it fits in iwr ? */
                        if ((descr->get_args & IW_PRIV_SIZE_FIXED) &&
                           (extra_size <= IFNAMSIZ))
                                extra_size = 0;
                }
        }
        *descrp = descr;
        return extra_size;
}

static int ioctl_private_iw_point(struct iw_point *iwp, unsigned int cmd,
                                  const struct iw_priv_args *descr,
                                  iw_handler handler, struct net_device *dev,
                                  struct iw_request_info *info, int extra_size)
{
        char *extra;
        int err;

        /* Check what user space is giving us */
        if (IW_IS_SET(cmd)) {
                if (!iwp->pointer && iwp->length != 0)
                        return -EFAULT;

                if (iwp->length > (descr->set_args & IW_PRIV_SIZE_MASK))
                        return -E2BIG;
        } else if (!iwp->pointer)
                return -EFAULT;

        extra = kzalloc(extra_size, GFP_KERNEL);
        if (!extra)
                return -ENOMEM;

        /* If it is a SET, get all the extra data in here */
        if (IW_IS_SET(cmd) && (iwp->length != 0)) {
                if (copy_from_user(extra, iwp->pointer, extra_size)) {
                        err = -EFAULT;
                        goto out;
                }
        }

        /* Call the handler */
        err = handler(dev, info, (union iwreq_data *) iwp, extra);

        /* If we have something to return to the user */
        if (!err && IW_IS_GET(cmd)) {
                /* Adjust for the actual length if it's variable,
                 * avoid leaking kernel bits outside.
                 */
                if (!(descr->get_args & IW_PRIV_SIZE_FIXED))
                        extra_size = adjust_priv_size(descr->get_args, iwp);

                if (copy_to_user(iwp->pointer, extra, extra_size))
                        err =  -EFAULT;
        }

out:
        kfree(extra);
        return err;
}

int ioctl_private_call(struct net_device *dev, struct iwreq *iwr,
                       unsigned int cmd, struct iw_request_info *info,
                       iw_handler handler)
{
        int extra_size = 0, ret = -EINVAL;
        const struct iw_priv_args *descr;

        extra_size = get_priv_descr_and_size(dev, cmd, &descr);

        /* Check if we have a pointer to user space data or not. */
        if (extra_size == 0) {
                /* No extra arguments. Trivial to handle */
                ret = handler(dev, info, &(iwr->u), (char *) &(iwr->u));
        } else {
                ret = ioctl_private_iw_point(&iwr->u.data, cmd, descr,
                                             handler, dev, info, extra_size);
        }

        /* Call commit handler if needed and defined */
        if (ret == -EIWCOMMIT)
                ret = call_commit_handler(dev);

        return ret;
}

#ifdef CONFIG_COMPAT
int compat_private_call(struct net_device *dev, struct iwreq *iwr,
                        unsigned int cmd, struct iw_request_info *info,
                        iw_handler handler)
{
        const struct iw_priv_args *descr;
        int ret, extra_size;

        extra_size = get_priv_descr_and_size(dev, cmd, &descr);

        /* Check if we have a pointer to user space data or not. */
        if (extra_size == 0) {
                /* No extra arguments. Trivial to handle */
                ret = handler(dev, info, &(iwr->u), (char *) &(iwr->u));
        } else {
                struct compat_iw_point *iwp_compat;
                struct iw_point iwp;

                iwp_compat = (struct compat_iw_point *) &iwr->u.data;
                iwp.pointer = compat_ptr(iwp_compat->pointer);
                iwp.length = iwp_compat->length;
                iwp.flags = iwp_compat->flags;

                ret = ioctl_private_iw_point(&iwp, cmd, descr,
                                             handler, dev, info, extra_size);

                iwp_compat->pointer = ptr_to_compat(iwp.pointer);
                iwp_compat->length = iwp.length;
                iwp_compat->flags = iwp.flags;
        }

        /* Call commit handler if needed and defined */
        if (ret == -EIWCOMMIT)
                ret = call_commit_handler(dev);

        return ret;
}
#endif