Re: [PATCH] mac80211 : fix a race with update_tkip_key

gregor kowski
2009-06-19T19:37:09Z

Update : I changed the logic. There is a single flag per key, tracking
if we send the key instead of a flag per rx queue.

The mac80211 tkip code won't call update_tkip_key, if some rx packets
get received without KEY_FLAG_UPLOADED_TO_HARDWARE. This can happen on
first packet because the hardware key stuff is called asynchronously with
todo workqueue.

This patch workaround that by tracking if we send the key to hardware.

Signed-off-by: Gregor Kowski <gregor.kowski@gmail.com>
Index: linux-2.6/net/mac80211/tkip.c
===================================================================
--- linux-2.6.orig/net/mac80211/tkip.c 2009-06-19 19:13:47.000000000 +0000
+++ linux-2.6/net/mac80211/tkip.c 2009-06-19 19:21:50.000000000 +0000
@@ -282,6 +282,7 @@
key->u.tkip.rx[queue].iv32 != iv32) {
/* IV16 wrapped around - perform TKIP phase 1 */
tkip_mixing_phase1(tk, &key->u.tkip.rx[queue], ta, iv32);
+ key->u.tkip.rx_tkip_key_sent = 0;
#ifdef CONFIG_MAC80211_TKIP_DEBUG
{
int i;
@@ -298,19 +299,21 @@
printk("\n");
}
#endif
- if (key->local->ops->update_tkip_key &&
- key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
- u8 bcast[ETH_ALEN] =
- {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
- u8 *sta_addr = key->sta->sta.addr;
+ }
+ if (key->local->ops->update_tkip_key &&
+ key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
+ !key->u.tkip.rx_tkip_key_sent) {
+ u8 bcast[ETH_ALEN] =
+ {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+ u8 *sta_addr = key->sta->sta.addr;

- if (is_multicast_ether_addr(ra))
- sta_addr = bcast;
+ if (is_multicast_ether_addr(ra))
+ sta_addr = bcast;

- key->local->ops->update_tkip_key(
- local_to_hw(key->local), &key->conf,
- sta_addr, iv32, key->u.tkip.rx[queue].p1k);
- }
+ key->local->ops->update_tkip_key(
+ local_to_hw(key->local), &key->conf,
+ sta_addr, iv32, key->u.tkip.rx[queue].p1k);
+ key->u.tkip.rx_tkip_key_sent = 1;
}

tkip_mixing_phase2(tk, &key->u.tkip.rx[queue], iv16, rc4key);
Index: linux-2.6/net/mac80211/key.h
===================================================================
--- linux-2.6.orig/net/mac80211/key.h 2009-06-19 19:22:20.000000000 +0000
+++ linux-2.6/net/mac80211/key.h 2009-06-19 19:22:31.000000000 +0000
@@ -86,6 +86,7 @@

/* last received RSC */
struct tkip_ctx rx[NUM_RX_DATA_QUEUES];
+ int rx_tkip_key_sent;
} tkip;
struct {
u8 tx_pn[6];