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[MAC80211]: Improve sanity checks on injected packets 

Michael Wu noticed that the skb length checking is not taken care of enough when
a packet is presented on the Monitor interface for injection.

This patch improves the sanity checking and removes fake offsets placed
into the skb network and transport header.

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 2007-07-27 15:43:24 +02:00 committed by David S. Miller
parent dfe6e81dea
commit 9b8a74e348
1 changed files with 28 additions and 20 deletions
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48
net/mac80211/tx.c
View File

@ -1270,46 +1270,54 @@ int ieee80211_monitor_start_xmit(struct sk_buff *skb,
struct ieee80211_tx_packet_data *pkt_data;
struct ieee80211_radiotap_header *prthdr =
(struct ieee80211_radiotap_header *)skb->data;
u16 len;
u16 len_rthdr;
/*
* there must be a radiotap header at the
* start in this case
*/
if (unlikely(prthdr->it_version)) {
/* only version 0 is supported */
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
/* check for not even having the fixed radiotap header part */
if (unlikely(skb->len < sizeof(struct ieee80211_radiotap_header)))
goto fail; /* too short to be possibly valid */
/* is it a header version we can trust to find length from? */
if (unlikely(prthdr->it_version))
goto fail; /* only version 0 is supported */
/* then there must be a radiotap header with a length we can use */
len_rthdr = ieee80211_get_radiotap_len(skb->data);
/* does the skb contain enough to deliver on the alleged length? */
if (unlikely(skb->len < len_rthdr))
goto fail; /* skb too short for claimed rt header extent */
skb->dev = local->mdev;
pkt_data = (struct ieee80211_tx_packet_data *)skb->cb;
memset(pkt_data, 0, sizeof(*pkt_data));
/* needed because we set skb device to master */
pkt_data->ifindex = 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(struct ieee80211_hdr));
skb_set_transport_header(skb, len + sizeof(struct ieee80211_hdr));
skb_set_mac_header(skb, len_rthdr);
/*
* pass the radiotap header up to
* the next stage intact
* these are just fixed to the end of the rt area since we
* don't have any better information and at this point, nobody cares
*/
dev_queue_xmit(skb);
skb_set_network_header(skb, len_rthdr);
skb_set_transport_header(skb, len_rthdr);
/* pass the radiotap header up to the next stage intact */
dev_queue_xmit(skb);
return NETDEV_TX_OK;
fail:
dev_kfree_skb(skb);
return NETDEV_TX_OK; /* meaning, we dealt with the skb */
}
/**