[PATCH] ieee80211: TKIP and CCMP replay check rework

Signed-off-by: Hong Liu <hong.liu@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/net/ieee80211/ieee80211_crypt_ccmp.c b/net/ieee80211/ieee80211_crypt_ccmp.c
index ed90a8af1444..098c66846339 100644
--- a/net/ieee80211/ieee80211_crypt_ccmp.c
+++ b/net/ieee80211/ieee80211_crypt_ccmp.c
@@ -271,6 +271,27 @@ static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
         return 0;
 }
 
+/*
+ * deal with seq counter wrapping correctly.
+ * refer to timer_after() for jiffies wrapping handling
+ */
+static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
+{
+        u32 iv32_n, iv16_n;
+        u32 iv32_o, iv16_o;
+
+        iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
+        iv16_n = (pn_n[4] << 8) | pn_n[5];
+
+        iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
+        iv16_o = (pn_o[4] << 8) | pn_o[5];
+
+        if ((s32)iv32_n - (s32)iv32_o < 0 ||
+            (iv32_n == iv32_o && iv16_n <= iv16_o))
+                return 1;
+        return 0;
+}
+
 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 {
         struct ieee80211_ccmp_data *key = priv;
@@ -323,7 +344,7 @@ static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
         pn[5] = pos[0];
         pos += 8;
 
-        if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
+        if (ccmp_replay_check(pn, key->rx_pn)) {
                 if (net_ratelimit()) {
                         printk(KERN_DEBUG "CCMP: replay detected: STA=" MAC_FMT
                                " previous PN %02x%02x%02x%02x%02x%02x "