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[PATCH] mac80211: Monitor mode radiotap-based packet injection

Browse source 
Signed-off-by: Andy Green <andy@warmcat.com>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Andy Green 2007-07-10 19:32:07 +02:00 committed by John W. Linville
parent 179f831bc3
commit e4c967c6d8
1 changed files with 224 additions and 10 deletions
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234
net/mac80211/ieee80211.c
View file

@ -24,6 +24,7 @@
#include <linux/compiler.h>
#include <linux/bitmap.h>
#include <net/cfg80211.h>
#include <asm/unaligned.h>
#include "ieee80211_common.h"
#include "ieee80211_i.h"
@ -1118,7 +1119,138 @@ ieee80211_tx_h_ps_buf(struct ieee80211_txrx_data *tx)
}
static void inline
/*
* deal with packet injection down monitor interface
* with Radiotap Header -- only called for monitor mode interface
*/
static ieee80211_txrx_result
__ieee80211_parse_tx_radiotap(
struct ieee80211_txrx_data *tx,
struct sk_buff *skb, struct ieee80211_tx_control *control)
{
/*
* this is the moment to interpret and discard the radiotap header that
* must be at the start of the packet injected in Monitor mode
*
* Need to take some care with endian-ness since radiotap
* args are little-endian
*/
struct ieee80211_radiotap_iterator iterator;
struct ieee80211_radiotap_header *rthdr =
(struct ieee80211_radiotap_header *) skb->data;
struct ieee80211_hw_mode *mode = tx->local->hw.conf.mode;
int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len);
/*
* default control situation for all injected packets
* FIXME: this does not suit all usage cases, expand to allow control
*/
control->retry_limit = 1; /* no retry */
control->key_idx = -1; /* no encryption key */
control->flags &= ~(IEEE80211_TXCTL_USE_RTS_CTS |
IEEE80211_TXCTL_USE_CTS_PROTECT);
control->flags |= IEEE80211_TXCTL_DO_NOT_ENCRYPT |
IEEE80211_TXCTL_NO_ACK;
control->antenna_sel_tx = 0; /* default to default antenna */
/*
* for every radiotap entry that is present
* (ieee80211_radiotap_iterator_next returns -ENOENT when no more
* entries present, or -EINVAL on error)
*/
while (!ret) {
int i, target_rate;
ret = ieee80211_radiotap_iterator_next(&iterator);
if (ret)
continue;
/* see if this argument is something we can use */
switch (iterator.this_arg_index) {
/*
* You must take care when dereferencing iterator.this_arg
* for multibyte types... the pointer is not aligned. Use
* get_unaligned((type *)iterator.this_arg) to dereference
* iterator.this_arg for type "type" safely on all arches.
*/
case IEEE80211_RADIOTAP_RATE:
/*
* radiotap rate u8 is in 500kbps units eg, 0x02=1Mbps
* ieee80211 rate int is in 100kbps units eg, 0x0a=1Mbps
*/
target_rate = (*iterator.this_arg) * 5;
for (i = 0; i < mode->num_rates; i++) {
struct ieee80211_rate *r = &mode->rates[i];
if (r->rate > target_rate)
continue;
control->rate = r;
if (r->flags & IEEE80211_RATE_PREAMBLE2)
control->tx_rate = r->val2;
else
control->tx_rate = r->val;
/* end on exact match */
if (r->rate == target_rate)
i = mode->num_rates;
}
break;
case IEEE80211_RADIOTAP_ANTENNA:
/*
* radiotap uses 0 for 1st ant, mac80211 is 1 for
* 1st ant
*/
control->antenna_sel_tx = (*iterator.this_arg) + 1;
break;
case IEEE80211_RADIOTAP_DBM_TX_POWER:
control->power_level = *iterator.this_arg;
break;
case IEEE80211_RADIOTAP_FLAGS:
if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {
/*
* this indicates that the skb we have been
* handed has the 32-bit FCS CRC at the end...
* we should react to that by snipping it off
* because it will be recomputed and added
* on transmission
*/
if (skb->len < (iterator.max_length + FCS_LEN))
return TXRX_DROP;
skb_trim(skb, skb->len - FCS_LEN);
}
break;
default:
break;
}
}
if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */
return TXRX_DROP;
/*
* remove the radiotap header
* iterator->max_length was sanity-checked against
* skb->len by iterator init
*/
skb_pull(skb, iterator.max_length);
return TXRX_CONTINUE;
}
static ieee80211_txrx_result inline
__ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
struct sk_buff *skb,
struct net_device *dev,
@ -1126,6 +1258,9 @@ __ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
{
struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct ieee80211_sub_if_data *sdata;
ieee80211_txrx_result res = TXRX_CONTINUE;
int hdrlen;
memset(tx, 0, sizeof(*tx));
@ -1135,7 +1270,32 @@ __ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
tx->sdata = IEEE80211_DEV_TO_SUB_IF(dev);
tx->sta = sta_info_get(local, hdr->addr1);
tx->fc = le16_to_cpu(hdr->frame_control);
/*
* set defaults for things that can be set by
* injected radiotap headers
*/
control->power_level = local->hw.conf.power_level;
control->antenna_sel_tx = local->hw.conf.antenna_sel_tx;
if (local->sta_antenna_sel != STA_ANTENNA_SEL_AUTO && tx->sta)
control->antenna_sel_tx = tx->sta->antenna_sel_tx;
/* process and remove the injection radiotap header */
sdata = IEEE80211_DEV_TO_SUB_IF(dev);
if (unlikely(sdata->type == IEEE80211_IF_TYPE_MNTR)) {
if (__ieee80211_parse_tx_radiotap(tx, skb, control) ==
TXRX_DROP) {
return TXRX_DROP;
}
/*
* we removed the radiotap header after this point,
* we filled control with what we could use
* set to the actual ieee header now
*/
hdr = (struct ieee80211_hdr *) skb->data;
res = TXRX_QUEUED; /* indication it was monitor packet */
}
tx->u.tx.control = control;
tx->u.tx.unicast = !is_multicast_ether_addr(hdr->addr1);
if (is_multicast_ether_addr(hdr->addr1))
@ -1152,9 +1312,6 @@ __ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
control->flags |= IEEE80211_TXCTL_CLEAR_DST_MASK;
tx->sta->clear_dst_mask = 0;
}
control->antenna_sel_tx = local->hw.conf.antenna_sel_tx;
if (local->sta_antenna_sel != STA_ANTENNA_SEL_AUTO && tx->sta)
control->antenna_sel_tx = tx->sta->antenna_sel_tx;
hdrlen = ieee80211_get_hdrlen(tx->fc);
if (skb->len > hdrlen + sizeof(rfc1042_header) + 2) {
u8 *pos = &skb->data[hdrlen + sizeof(rfc1042_header)];
@ -1162,6 +1319,7 @@ __ieee80211_tx_prepare(struct ieee80211_txrx_data *tx,
}
control->flags |= IEEE80211_TXCTL_FIRST_FRAGMENT;
return res;
}
static int inline is_ieee80211_device(struct net_device *dev,
@ -1274,7 +1432,7 @@ static int ieee80211_tx(struct net_device *dev, struct sk_buff *skb,
struct sta_info *sta;
ieee80211_tx_handler *handler;
struct ieee80211_txrx_data tx;
ieee80211_txrx_result res = TXRX_DROP;
ieee80211_txrx_result res = TXRX_DROP, res_prepare;
int ret, i;
WARN_ON(__ieee80211_queue_pending(local, control->queue));
@ -1284,15 +1442,26 @@ static int ieee80211_tx(struct net_device *dev, struct sk_buff *skb,
return 0;
}
__ieee80211_tx_prepare(&tx, skb, dev, control);
res_prepare = __ieee80211_tx_prepare(&tx, skb, dev, control);
if (res_prepare == TXRX_DROP) {
dev_kfree_skb(skb);
return 0;
}
sta = tx.sta;
tx.u.tx.mgmt_interface = mgmt;
tx.u.tx.mode = local->hw.conf.mode;
for (handler = local->tx_handlers; *handler != NULL; handler++) {
res = (*handler)(&tx);
if (res != TXRX_CONTINUE)
break;
if (res_prepare == TXRX_QUEUED) { /* if it was an injected packet */
res = TXRX_CONTINUE;
} else {
for (handler = local->tx_handlers; *handler != NULL;
handler++) {
res = (*handler)(&tx);
if (res != TXRX_CONTINUE)
break;
}
}
skb = tx.skb; /* handlers are allowed to change skb */
@ -1531,6 +1700,51 @@ static int ieee80211_subif_start_xmit(struct sk_buff *skb,
goto fail;
}
if (unlikely(sdata->type == IEEE80211_IF_TYPE_MNTR)) {
struct ieee80211_radiotap_header *prthdr =
(struct ieee80211_radiotap_header *)skb->data;
u16 len;
/*
* there must be a radiotap header at the
* start in this case
*/
if (unlikely(prthdr->it_version)) {
/* only version 0 is supported */
ret = 0;
goto fail;
}
skb->dev = local->mdev;
pkt_data = (struct ieee80211_tx_packet_data *)skb->cb;
memset(pkt_data, 0, sizeof(*pkt_data));
pkt_data->ifindex = sdata->dev->ifindex;
pkt_data->mgmt_iface = 0;
pkt_data->do_not_encrypt = 1;
/* above needed because we set skb device to master */
/*
* fix up the pointers accounting for the radiotap
* header still being in there. We are being given
* a precooked IEEE80211 header so no need for
* normal processing
*/
len = le16_to_cpu(get_unaligned(&prthdr->it_len));
skb_set_mac_header(skb, len);
skb_set_network_header(skb, len + sizeof(hdr));
skb_set_transport_header(skb, len + sizeof(hdr));
/*
* pass the radiotap header up to
* the next stage intact
*/
dev_queue_xmit(skb);
return 0;
}
nh_pos = skb_network_header(skb) - skb->data;
h_pos = skb_transport_header(skb) - skb->data;