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mac80211: fix MU-MIMO follow-MAC mode 

There are two bugs in the follow-MAC code:
 * it treats the radiotap header as the 802.11 header
   (therefore it can't possibly work)
 * it doesn't verify that the skb data it accesses is actually
   present in the header, which is mitigated by the first point

Fix this by moving all of this out into a separate function.
This function copies the data it needs using skb_copy_bits()
to make sure it can be accessed if it's paged, and offsets
that by the possibly present vendor radiotap header.

This also makes all those conditions more readable.

Cc: stable@vger.kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2017-04-13 14:23:49 +02:00
parent fc9c89b19c
commit 9e478066ea
1 changed files with 47 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
net/mac80211/rx.c
View File

@ -208,6 +208,51 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
return len;
}
static void ieee80211_handle_mu_mimo_mon(struct ieee80211_sub_if_data *sdata,
struct sk_buff *skb,
int rtap_vendor_space)
{
struct {
struct ieee80211_hdr_3addr hdr;
u8 category;
u8 action_code;
} __packed action;
if (!sdata)
return;
BUILD_BUG_ON(sizeof(action) != IEEE80211_MIN_ACTION_SIZE + 1);
if (skb->len < rtap_vendor_space + sizeof(action) +
VHT_MUMIMO_GROUPS_DATA_LEN)
return;
if (!is_valid_ether_addr(sdata->u.mntr.mu_follow_addr))
return;
skb_copy_bits(skb, rtap_vendor_space, &action, sizeof(action));
if (!ieee80211_is_action(action.hdr.frame_control))
return;
if (action.category != WLAN_CATEGORY_VHT)
return;
if (action.action_code != WLAN_VHT_ACTION_GROUPID_MGMT)
return;
if (!ether_addr_equal(action.hdr.addr1, sdata->u.mntr.mu_follow_addr))
return;
skb = skb_copy(skb, GFP_ATOMIC);
if (!skb)
return;
skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
skb_queue_tail(&sdata->skb_queue, skb);
ieee80211_queue_work(&sdata->local->hw, &sdata->work);
}
/*
* ieee80211_add_rx_radiotap_header - add radiotap header
*
@ -515,7 +560,6 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
struct net_device *prev_dev = NULL;
int present_fcs_len = 0;
unsigned int rtap_vendor_space = 0;
struct ieee80211_mgmt *mgmt;
struct ieee80211_sub_if_data *monitor_sdata =
rcu_dereference(local->monitor_sdata);
@ -553,6 +597,8 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
return remove_monitor_info(local, origskb, rtap_vendor_space);
}
ieee80211_handle_mu_mimo_mon(monitor_sdata, origskb, rtap_vendor_space);
/* room for the radiotap header based on driver features */
rt_hdrlen = ieee80211_rx_radiotap_hdrlen(local, status, origskb);
needed_headroom = rt_hdrlen - rtap_vendor_space;
@ -618,23 +664,6 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
ieee80211_rx_stats(sdata->dev, skb->len);
}
mgmt = (void *)skb->data;
if (monitor_sdata &&
skb->len >= IEEE80211_MIN_ACTION_SIZE + 1 + VHT_MUMIMO_GROUPS_DATA_LEN &&
ieee80211_is_action(mgmt->frame_control) &&
mgmt->u.action.category == WLAN_CATEGORY_VHT &&
mgmt->u.action.u.vht_group_notif.action_code == WLAN_VHT_ACTION_GROUPID_MGMT &&
is_valid_ether_addr(monitor_sdata->u.mntr.mu_follow_addr) &&
ether_addr_equal(mgmt->da, monitor_sdata->u.mntr.mu_follow_addr)) {
struct sk_buff *mu_skb = skb_copy(skb, GFP_ATOMIC);
if (mu_skb) {
mu_skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
skb_queue_tail(&monitor_sdata->skb_queue, mu_skb);
ieee80211_queue_work(&local->hw, &monitor_sdata->work);
}
}
if (prev_dev) {
skb->dev = prev_dev;
netif_receive_skb(skb);