This patch allows drivers to indicate bad FCS/PLCP CRC to the stack and
have the stack drop packets like that except for monitor interfaces.
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
Changes since v1:
* filter bad frames early in the RX code and don't count
them nor try to get a STA for them
include/net/mac80211.h | 6 ++++++
net/mac80211/rx.c | 32 +++++++++++++++++++++++++++++---
2 files changed, 35 insertions(+), 3 deletions(-)
--- wireless-dev.orig/net/mac80211/rx.c 2007-09-06 01:35:00.204453431 +0200
+++ wireless-dev/net/mac80211/rx.c 2007-09-06 01:35:11.644453431 +0200
@@ -156,6 +156,8 @@ ieee80211_rx_monitor(struct net_device *
__le16 chan_freq;
__le16 chan_flags;
u8 antsignal;
+ u8 padding_for_rxflags;
+ __le16 rx_flags;
} __attribute__ ((packed)) *rthdr;
skb->dev = dev;
@@ -180,12 +182,21 @@ ieee80211_rx_monitor(struct net_device *
cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
(1 << IEEE80211_RADIOTAP_RATE) |
(1 << IEEE80211_RADIOTAP_CHANNEL) |
- (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL));
+ (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) |
+ (1 << IEEE80211_RADIOTAP_RX_FLAGS));
rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ?
IEEE80211_RADIOTAP_F_FCS : 0;
+
+ /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */
+ rthdr->rx_flags = 0;
+ if (status->flag &
+ (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
+ rthdr->rx_flags |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS);
+
rate = ieee80211_get_rate(local, status->phymode, status->rate);
if (rate)
rthdr->rate = rate->rate / 5;
+
rthdr->chan_freq = cpu_to_le16(status->freq);
rthdr->chan_flags =
status->phymode == MODE_IEEE80211A ?
@@ -213,6 +224,15 @@ ieee80211_rx_h_monitor(struct ieee80211_
return TXRX_QUEUED;
}
+ /*
+ * Drop frames with failed FCS/PLCP checksums here, they are only
+ * relevant for monitor mode, the rest of the stack should never
+ * see them.
+ */
+ if (rx->u.rx.status->flag &
+ (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
+ return TXRX_DROP;
+
if (rx->u.rx.status->flag & RX_FLAG_RADIOTAP)
skb_pull(rx->skb, ieee80211_get_radiotap_len(rx->skb->data));
@@ -1505,6 +1525,7 @@ void __ieee80211_rx(struct ieee80211_hw
struct ieee80211_sub_if_data *prev = NULL;
struct sk_buff *skb_new;
u8 *bssid;
+ int bogon;
if (status->flag & RX_FLAG_RADIOTAP) {
radiotap_len = ieee80211_get_radiotap_len(skb->data);
@@ -1525,10 +1546,15 @@ void __ieee80211_rx(struct ieee80211_hw
rx.u.rx.status = status;
rx.fc = skb->len >= 2 ? le16_to_cpu(hdr->frame_control) : 0;
type = rx.fc & IEEE80211_FCTL_FTYPE;
- if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT)
+
+ bogon = status->flag & (RX_FLAG_FAILED_FCS_CRC |
+ RX_FLAG_FAILED_PLCP_CRC);
+
+ if (!bogon && (type == IEEE80211_FTYPE_DATA ||
+ type == IEEE80211_FTYPE_MGMT))
local->dot11ReceivedFragmentCount++;
- if (skb->len >= 16) {
+ if (!bogon && skb->len >= 16) {
sta = rx.sta = sta_info_get(local, hdr->addr2);
if (sta) {
rx.dev = rx.sta->dev;
--- wireless-dev.orig/include/net/mac80211.h 2007-09-06 01:35:00.244453431 +0200
+++ wireless-dev/include/net/mac80211.h 2007-09-06 01:35:11.644453431 +0200
@@ -235,6 +235,10 @@ struct ieee80211_tx_control {
* @RX_FLAG_IV_STRIPPED: The IV/ICV are stripped from this frame.
* If this flag is set, the stack cannot do any replay detection
* hence the driver or hardware will have to do that.
+ * @RX_FLAG_FAILED_FCS_CRC: Set this flag if the FCS check failed on
+ * the frame.
+ * @RX_FLAG_FAILED_PLCP_CRC: Set this flag if the PCLP check failed on
+ * the frame.
*/
enum mac80211_rx_flags {
RX_FLAG_MMIC_ERROR = 1<<0,
@@ -242,6 +246,8 @@ enum mac80211_rx_flags {
RX_FLAG_RADIOTAP = 1<<2,
RX_FLAG_MMIC_STRIPPED = 1<<3,
RX_FLAG_IV_STRIPPED = 1<<4,
+ RX_FLAG_FAILED_FCS_CRC = 1<<5,
+ RX_FLAG_FAILED_PLCP_CRC = 1<<6,
};
/**
--
-
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