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freebsd/sys/net80211/ieee80211_radiotap.c
Adrian Chadd 8a3860d5b4 Extend the radiotap code to be aware of the size of any extra vendor
bitmaps that may occur.

The way this works is:

* the beginning of the radiotap frame has a 32 bit "radiotap" namespace
  bitmap;
* if the vendor bitmap bit is set, then the next bitmap will be interpreted
  as a vendor bitmap;
* this can keep going on and on (ie, more vendor and radiotap namespace
  bitmaps can be added) until the last bitmap with no "more bitmaps" set.

Now, the radiotap code gets its grubby fingers into the supplied
radiotap rx/tx buffer and replaces the channel configuration
for each frame.  I don't know why it's not up to the drivers themselves
to do this, but I digress.  So, if a vendor bitmap (or two, etc) exists,
the offset calculations will be all completely wrong.

This particular patch introduces ieee80211_radiotap_attachv(), which
includes the number of vendor bitmaps (well, any other bitmaps, vendor
or otherwise) between the end of the bitmap/header and the start of the
actual radiotap field entries.  This makes the radiotap calculations
"right", so it correctly calculates where to overwrite the channel
configuration.

The long term fix is to go through and make each driver update the channel
configuration, as some of the fields are already being updated.

That, however, is a longer term fix that will need each driver fixed.

I leave that as an exercise to someone in the future.
2012-06-18 02:08:04 +00:00

374 lines
10 KiB
C

/*-
* Copyright (c) 2009 Sam Leffler, Errno Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* IEEE 802.11 radiotap support.
*/
#include "opt_wlan.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <net/bpf.h>
#include <net/if.h>
#include <net/if_llc.h>
#include <net/if_media.h>
#include <net80211/ieee80211_var.h>
static int radiotap_offset(struct ieee80211_radiotap_header *, int, int);
void
ieee80211_radiotap_attach(struct ieee80211com *ic,
struct ieee80211_radiotap_header *th, int tlen, uint32_t tx_radiotap,
struct ieee80211_radiotap_header *rh, int rlen, uint32_t rx_radiotap)
{
ieee80211_radiotap_attachv(ic, th, tlen, 0, tx_radiotap,
rh, rlen, 0, rx_radiotap);
}
void
ieee80211_radiotap_attachv(struct ieee80211com *ic,
struct ieee80211_radiotap_header *th,
int tlen, int n_tx_v, uint32_t tx_radiotap,
struct ieee80211_radiotap_header *rh,
int rlen, int n_rx_v, uint32_t rx_radiotap)
{
#define B(_v) (1<<(_v))
int off;
th->it_len = htole16(roundup2(tlen, sizeof(uint32_t)));
th->it_present = htole32(tx_radiotap);
ic->ic_th = th;
/* calculate offset to channel data */
off = -1;
if (tx_radiotap & B(IEEE80211_RADIOTAP_CHANNEL))
off = radiotap_offset(th, n_tx_v, IEEE80211_RADIOTAP_CHANNEL);
else if (tx_radiotap & B(IEEE80211_RADIOTAP_XCHANNEL))
off = radiotap_offset(th, n_tx_v, IEEE80211_RADIOTAP_XCHANNEL);
if (off == -1) {
if_printf(ic->ic_ifp, "%s: no tx channel, radiotap 0x%x\n",
__func__, tx_radiotap);
/* NB: we handle this case but data will have no chan spec */
} else
ic->ic_txchan = ((uint8_t *) th) + off;
rh->it_len = htole16(roundup2(rlen, sizeof(uint32_t)));
rh->it_present = htole32(rx_radiotap);
ic->ic_rh = rh;
/* calculate offset to channel data */
off = -1;
if (rx_radiotap & B(IEEE80211_RADIOTAP_CHANNEL))
off = radiotap_offset(rh, n_rx_v, IEEE80211_RADIOTAP_CHANNEL);
else if (rx_radiotap & B(IEEE80211_RADIOTAP_XCHANNEL))
off = radiotap_offset(rh, n_rx_v, IEEE80211_RADIOTAP_XCHANNEL);
if (off == -1) {
if_printf(ic->ic_ifp, "%s: no rx channel, radiotap 0x%x\n",
__func__, rx_radiotap);
/* NB: we handle this case but data will have no chan spec */
} else
ic->ic_rxchan = ((uint8_t *) rh) + off;
#undef B
}
void
ieee80211_radiotap_detach(struct ieee80211com *ic)
{
}
void
ieee80211_radiotap_vattach(struct ieee80211vap *vap)
{
struct ieee80211com *ic = vap->iv_ic;
struct ieee80211_radiotap_header *th = ic->ic_th;
if (th != NULL && ic->ic_rh != NULL) {
/* radiotap DLT for raw 802.11 frames */
bpfattach2(vap->iv_ifp, DLT_IEEE802_11_RADIO,
sizeof(struct ieee80211_frame) + le16toh(th->it_len),
&vap->iv_rawbpf);
}
}
void
ieee80211_radiotap_vdetach(struct ieee80211vap *vap)
{
/* NB: bpfattach is called by ether_ifdetach and claims all taps */
}
static void
set_channel(void *p, const struct ieee80211_channel *c)
{
struct {
uint16_t freq;
uint16_t flags;
} *rc = p;
rc->freq = htole16(c->ic_freq);
rc->flags = htole16(c->ic_flags);
}
static void
set_xchannel(void *p, const struct ieee80211_channel *c)
{
struct {
uint32_t flags;
uint16_t freq;
uint8_t ieee;
uint8_t maxpow;
} *rc = p;
rc->flags = htole32(c->ic_flags);
rc->freq = htole16(c->ic_freq);
rc->ieee = c->ic_ieee;
rc->maxpow = c->ic_maxregpower;
}
/*
* Update radiotap state on channel change.
*/
void
ieee80211_radiotap_chan_change(struct ieee80211com *ic)
{
if (ic->ic_rxchan != NULL) {
struct ieee80211_radiotap_header *rh = ic->ic_rh;
if (rh->it_present & htole32(1<<IEEE80211_RADIOTAP_XCHANNEL))
set_xchannel(ic->ic_rxchan, ic->ic_curchan);
else if (rh->it_present & htole32(1<<IEEE80211_RADIOTAP_CHANNEL))
set_channel(ic->ic_rxchan, ic->ic_curchan);
}
if (ic->ic_txchan != NULL) {
struct ieee80211_radiotap_header *th = ic->ic_th;
if (th->it_present & htole32(1<<IEEE80211_RADIOTAP_XCHANNEL))
set_xchannel(ic->ic_txchan, ic->ic_curchan);
else if (th->it_present & htole32(1<<IEEE80211_RADIOTAP_CHANNEL))
set_channel(ic->ic_txchan, ic->ic_curchan);
}
}
/*
* Distribute radiotap data (+packet) to all monitor mode
* vaps with an active tap other than vap0.
*/
static void
spam_vaps(struct ieee80211vap *vap0, struct mbuf *m,
struct ieee80211_radiotap_header *rh, int len)
{
struct ieee80211com *ic = vap0->iv_ic;
struct ieee80211vap *vap;
TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
if (vap != vap0 &&
vap->iv_opmode == IEEE80211_M_MONITOR &&
(vap->iv_flags_ext & IEEE80211_FEXT_BPF) &&
vap->iv_state != IEEE80211_S_INIT)
bpf_mtap2(vap->iv_rawbpf, rh, len, m);
}
}
/*
* Dispatch radiotap data for transmitted packet.
*/
void
ieee80211_radiotap_tx(struct ieee80211vap *vap0, struct mbuf *m)
{
struct ieee80211com *ic = vap0->iv_ic;
struct ieee80211_radiotap_header *th = ic->ic_th;
int len;
KASSERT(th != NULL, ("no tx radiotap header"));
len = le16toh(th->it_len);
if (vap0->iv_flags_ext & IEEE80211_FEXT_BPF)
bpf_mtap2(vap0->iv_rawbpf, th, len, m);
/*
* Spam monitor mode vaps.
*/
if (ic->ic_montaps != 0)
spam_vaps(vap0, m, th, len);
}
/*
* Dispatch radiotap data for received packet.
*/
void
ieee80211_radiotap_rx(struct ieee80211vap *vap0, struct mbuf *m)
{
struct ieee80211com *ic = vap0->iv_ic;
struct ieee80211_radiotap_header *rh = ic->ic_rh;
int len;
KASSERT(rh != NULL, ("no rx radiotap header"));
len = le16toh(rh->it_len);
if (vap0->iv_flags_ext & IEEE80211_FEXT_BPF)
bpf_mtap2(vap0->iv_rawbpf, rh, len, m);
/*
* Spam monitor mode vaps with unicast frames. Multicast
* frames are handled by passing through ieee80211_input_all
* which distributes copies to the monitor mode vaps.
*/
if (ic->ic_montaps != 0 && (m->m_flags & M_BCAST) == 0)
spam_vaps(vap0, m, rh, len);
}
/*
* Dispatch radiotap data for a packet received outside the normal
* rx processing path; this is used, for example, to handle frames
* received with errors that would otherwise be dropped.
*/
void
ieee80211_radiotap_rx_all(struct ieee80211com *ic, struct mbuf *m)
{
struct ieee80211_radiotap_header *rh = ic->ic_rh;
int len = le16toh(rh->it_len);
struct ieee80211vap *vap;
/* XXX locking? */
TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
if (ieee80211_radiotap_active_vap(vap) &&
vap->iv_state != IEEE80211_S_INIT)
bpf_mtap2(vap->iv_rawbpf, rh, len, m);
}
}
/*
* Return the offset of the specified item in the radiotap
* header description. If the item is not present or is not
* known -1 is returned.
*/
static int
radiotap_offset(struct ieee80211_radiotap_header *rh,
int n_vendor_attributes, int item)
{
static const struct {
size_t align, width;
} items[] = {
[IEEE80211_RADIOTAP_TSFT] = {
.align = sizeof(uint64_t),
.width = sizeof(uint64_t),
},
[IEEE80211_RADIOTAP_FLAGS] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_RATE] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_CHANNEL] = {
.align = sizeof(uint16_t),
.width = 2*sizeof(uint16_t),
},
[IEEE80211_RADIOTAP_FHSS] = {
.align = sizeof(uint16_t),
.width = sizeof(uint16_t),
},
[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_DBM_ANTNOISE] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_LOCK_QUALITY] = {
.align = sizeof(uint16_t),
.width = sizeof(uint16_t),
},
[IEEE80211_RADIOTAP_TX_ATTENUATION] = {
.align = sizeof(uint16_t),
.width = sizeof(uint16_t),
},
[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = {
.align = sizeof(uint16_t),
.width = sizeof(uint16_t),
},
[IEEE80211_RADIOTAP_DBM_TX_POWER] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_ANTENNA] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_DB_ANTNOISE] = {
.align = sizeof(uint8_t),
.width = sizeof(uint8_t),
},
[IEEE80211_RADIOTAP_XCHANNEL] = {
.align = sizeof(uint32_t),
.width = 2*sizeof(uint32_t),
},
[IEEE80211_RADIOTAP_MCS] = {
.align = sizeof(uint8_t),
.width = 3*sizeof(uint8_t),
},
};
uint32_t present = le32toh(rh->it_present);
int off, i;
off = sizeof(struct ieee80211_radiotap_header);
off += n_vendor_attributes * (sizeof(uint32_t));
for (i = 0; i < IEEE80211_RADIOTAP_EXT; i++) {
if ((present & (1<<i)) == 0)
continue;
if (items[i].align == 0) {
/* NB: unidentified element, don't guess */
printf("%s: unknown item %d\n", __func__, i);
return -1;
}
off = roundup2(off, items[i].align);
if (i == item) {
if (off + items[i].width > le16toh(rh->it_len)) {
/* NB: item does not fit in header data */
printf("%s: item %d not in header data, "
"off %d width %zu len %d\n", __func__, i,
off, items[i].width, le16toh(rh->it_len));
return -1;
}
return off;
}
off += items[i].width;
}
return -1;
}