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

[gregor kowski <gregor.kowski@gmail.com>]

The mac80211 tkip code won't call update_tkip_key, if rx packets
are 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 sent the key to the driver.

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	2009-12-08 20:37:41.000000000 +0000
+++ linux-2.6/net/mac80211/tkip.c	2009-12-08 20:42:23.000000000 +0000
@@ -100,7 +100,7 @@
 		p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
 		p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
 	}
-	ctx->initialized = 1;
+	ctx->state = TKIP_STATE_PHASE1_DONE;
 }

 static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
@@ -183,7 +183,7 @@
 	/* Update the p1k only when the iv16 in the packet wraps around, this
 	 * might occur after the wrap around of iv16 in the key in case of
 	 * fragmented packets. */
-	if (iv16 == 0 || !ctx->initialized)
+	if (iv16 == 0 || ctx->state == TKIP_STATE_NOT_INIT)
 		tkip_mixing_phase1(tk, ctx, hdr->addr2, iv32);

 	if (type == IEEE80211_TKIP_P1_KEY) {
@@ -209,7 +209,7 @@
 	const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];

 	/* Calculate per-packet key */
-	if (ctx->iv16 == 0 || !ctx->initialized)
+	if (ctx->iv16 == 0 || ctx->state == TKIP_STATE_NOT_INIT)
 		tkip_mixing_phase1(tk, ctx, ta, ctx->iv32);

 	tkip_mixing_phase2(tk, ctx, ctx->iv16, rc4key);
@@ -259,7 +259,7 @@
 	if ((keyid >> 6) != key->conf.keyidx)
 		return TKIP_DECRYPT_INVALID_KEYIDX;

-	if (key->u.tkip.rx[queue].initialized &&
+	if (key->u.tkip.rx[queue].state != TKIP_STATE_NOT_INIT &&
 	    (iv32 < key->u.tkip.rx[queue].iv32 ||
 	     (iv32 == key->u.tkip.rx[queue].iv32 &&
 	      iv16 <= key->u.tkip.rx[queue].iv16))) {
@@ -275,11 +275,11 @@

 	if (only_iv) {
 		res = TKIP_DECRYPT_OK;
-		key->u.tkip.rx[queue].initialized = 1;
+		key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 		goto done;
 	}

-	if (!key->u.tkip.rx[queue].initialized ||
+	if (key->u.tkip.rx[queue].state == TKIP_STATE_NOT_INIT ||
 	    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);
@@ -299,18 +299,20 @@
 			printk("\n");
 		}
 #endif
-		if (key->local->ops->update_tkip_key &&
-			key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
-			static const u8 bcast[ETH_ALEN] =
-				{0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
-			const u8 *sta_addr = key->sta->sta.addr;
-
-			if (is_multicast_ether_addr(ra))
-				sta_addr = bcast;
-
-			drv_update_tkip_key(key->local, &key->conf, sta_addr,
-					    iv32, key->u.tkip.rx[queue].p1k);
-		}
+	}
+	if (key->local->ops->update_tkip_key &&
+	    key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
+	    key->u.tkip.rx[queue].state != TKIP_STATE_PHASE1_HW_UPLOADED) {
+		static const u8 bcast[ETH_ALEN] =
+		{0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+		const u8 *sta_addr = key->sta->sta.addr;
+
+		if (is_multicast_ether_addr(ra))
+			sta_addr = bcast;
+
+		drv_update_tkip_key(key->local, &key->conf, sta_addr,
+				iv32, key->u.tkip.rx[queue].p1k);
+		key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 	}

 	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	2009-12-08 20:37:41.000000000 +0000
+++ linux-2.6/net/mac80211/key.h	2009-12-08 20:39:23.000000000 +0000
@@ -59,11 +59,17 @@
 	KEY_FLAG_TODO_DEFMGMTKEY	= BIT(6),
 };

+enum ieee80211_internal_tkip_state {
+	TKIP_STATE_NOT_INIT,
+	TKIP_STATE_PHASE1_DONE,
+	TKIP_STATE_PHASE1_HW_UPLOADED,
+};
+
 struct tkip_ctx {
 	u32 iv32;
 	u16 iv16;
 	u16 p1k[5];
-	int initialized;
+	enum ieee80211_internal_tkip_state state;
 };

 struct ieee80211_key {