mac80211: Fix TKIP replay protection immediately after key setup

[linux-2.6-microblaze.git] / net / mac80211 / tkip.c

diff --git a/net/mac80211/tkip.c b/net/mac80211/tkip.c
index 727dc9f..e7f57bb 100644 (file)
--- a/net/mac80211/tkip.c
+++ b/net/mac80211/tkip.c
@@ -263,9 +263,21 @@ int ieee80211_tkip_decrypt_data(struct arc4_ctx *ctx,
        if ((keyid >> 6) != key->conf.keyidx)
                return TKIP_DECRYPT_INVALID_KEYIDX;
 
-       if (rx_ctx->ctx.state != TKIP_STATE_NOT_INIT &&
-           (iv32 < rx_ctx->iv32 ||
-            (iv32 == rx_ctx->iv32 && iv16 <= rx_ctx->iv16)))
+       /* Reject replays if the received TSC is smaller than or equal to the
+        * last received value in a valid message, but with an exception for
+        * the case where a new key has been set and no valid frame using that
+        * key has yet received and the local RSC was initialized to 0. This
+        * exception allows the very first frame sent by the transmitter to be
+        * accepted even if that transmitter were to use TSC 0 (IEEE 802.11
+        * described TSC to be initialized to 1 whenever a new key is taken into
+        * use).
+        */
+       if (iv32 < rx_ctx->iv32 ||
+           (iv32 == rx_ctx->iv32 &&
+            (iv16 < rx_ctx->iv16 ||
+             (iv16 == rx_ctx->iv16 &&
+              (rx_ctx->iv32 || rx_ctx->iv16 ||
+               rx_ctx->ctx.state != TKIP_STATE_NOT_INIT)))))
                return TKIP_DECRYPT_REPLAY;
 
        if (only_iv) {