linux/net/wireless/wext-priv.c
Johannes Berg df6d02300f wext: fix potential private ioctl memory content leak
When a driver doesn't fill the entire buffer, old
heap contents may remain, and if it also doesn't
update the length properly, this old heap content
will be copied back to userspace.

It is very unlikely that this happens in any of
the drivers using private ioctls since it would
show up as junk being reported by iwpriv, but it
seems better to be safe here, so use kzalloc.

Reported-by: Jeff Mahoney <jeffm@suse.com>
Cc: stable@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2010-09-20 13:41:40 -04:00

249 lines
6.9 KiB
C

/*
* 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