From e4c967c6d88ca94365dd8e2a7bbd22eedb8d7ae7 Mon Sep 17 00:00:00 2001 From: Andy Green Date: Tue, 10 Jul 2007 19:32:07 +0200 Subject: [PATCH] [PATCH] mac80211: Monitor mode radiotap-based packet injection Signed-off-by: Andy Green Signed-off-by: Jiri Benc Signed-off-by: John W. Linville --- net/mac80211/ieee80211.c | 234 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 224 insertions(+), 10 deletions(-) diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c index 4e84f24fd439..8b57eaa2a271 100644 --- a/net/mac80211/ieee80211.c +++ b/net/mac80211/ieee80211.c @@ -24,6 +24,7 @@ #include #include #include +#include #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;