mac80211: fix radiotap header generation
In
commit 601ae7f25aea58f208a7f640f6174aac0652403a
Author: Bruno Randolf <br1@einfach.org>
Date: Thu May 8 19:22:43 2008 +0200
mac80211: make rx radiotap header more flexible
code was added that tried to align the radiotap header
position in memory based on the radiotap header length.
Quite obviously, that is completely useless.
Instead of trying to do that, use unaligned accesses
to generate the radiotap header. To properly do that,
we also need to mark struct ieee80211_radiotap_header
packed, but that is fine since it's already packed
(and it should be marked packed anyway since its a
wire format).
Cc: Bruno Randolf <br1@einfach.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/ieee80211_radiotap.h b/include/net/ieee80211_radiotap.h
index 23c3f3d..9d3d86a 100644
--- a/include/net/ieee80211_radiotap.h
+++ b/include/net/ieee80211_radiotap.h
@@ -80,7 +80,7 @@
* Additional extensions are made
* by setting bit 31.
*/
-};
+} __packed;
/* Name Data type Units
* ---- --------- -----
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 5c385e3..01df328 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -95,10 +95,6 @@
if (len & 1) /* padding for RX_FLAGS if necessary */
len++;
- /* make sure radiotap starts at a naturally aligned address */
- if (len % 8)
- len = roundup(len, 8);
-
return len;
}
@@ -116,6 +112,7 @@
struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
struct ieee80211_radiotap_header *rthdr;
unsigned char *pos;
+ u16 rx_flags = 0;
rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
memset(rthdr, 0, rtap_len);
@@ -134,7 +131,7 @@
/* IEEE80211_RADIOTAP_TSFT */
if (status->flag & RX_FLAG_TSFT) {
- *(__le64 *)pos = cpu_to_le64(status->mactime);
+ put_unaligned_le64(status->mactime, pos);
rthdr->it_present |=
cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
pos += 8;
@@ -166,17 +163,17 @@
pos++;
/* IEEE80211_RADIOTAP_CHANNEL */
- *(__le16 *)pos = cpu_to_le16(status->freq);
+ put_unaligned_le16(status->freq, pos);
pos += 2;
if (status->band == IEEE80211_BAND_5GHZ)
- *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM |
- IEEE80211_CHAN_5GHZ);
+ put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ,
+ pos);
else if (rate->flags & IEEE80211_RATE_ERP_G)
- *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM |
- IEEE80211_CHAN_2GHZ);
+ put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,
+ pos);
else
- *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_CCK |
- IEEE80211_CHAN_2GHZ);
+ put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ,
+ pos);
pos += 2;
/* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */
@@ -205,10 +202,11 @@
/* IEEE80211_RADIOTAP_RX_FLAGS */
/* ensure 2 byte alignment for the 2 byte field as required */
- if ((pos - (unsigned char *)rthdr) & 1)
+ if ((pos - (u8 *)rthdr) & 1)
pos++;
if (status->flag & RX_FLAG_FAILED_PLCP_CRC)
- *(__le16 *)pos |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADPLCP);
+ rx_flags |= IEEE80211_RADIOTAP_F_RX_BADPLCP;
+ put_unaligned_le16(rx_flags, pos);
pos += 2;
}
