mac80211: fix CMAC races

Just like TKIP and CCMP, CMAC has the PN race.
It might not actually be possible to hit it now
since there aren't multiple ACs for management
frames, but fix it anyway.

Also move scratch buffers onto the stack.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 13 deletions

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index 7691e4edc74a..3452d5e0a3cb 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -523,6 +523,16 @@ static void bip_aad(struct sk_buff *skb, u8 *aad)
 }
 
 
+static inline void bip_ipn_set64(u8 *d, u64 pn)
+{
+        *d++ = pn;
+        *d++ = pn >> 8;
+        *d++ = pn >> 16;
+        *d++ = pn >> 24;
+        *d++ = pn >> 32;
+        *d = pn >> 40;
+}
+
 static inline void bip_ipn_swap(u8 *d, const u8 *s)
 {
         *d++ = s[5];
@@ -541,8 +551,8 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         struct ieee80211_key *key = tx->key;
         struct ieee80211_mmie *mmie;
-        u8 *pn, aad[20];
-        int i;
+        u8 aad[20];
+        u64 pn64;
 
         if (info->control.hw_key)
                 return 0;
@@ -556,22 +566,17 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
         mmie->key_id = cpu_to_le16(key->conf.keyidx);
 
         /* PN = PN + 1 */
-        pn = key->u.aes_cmac.tx_pn;
+        pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);
 
-        for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) {
-                pn[i]++;
-                if (pn[i])
-                        break;
-        }
-        bip_ipn_swap(mmie->sequence_number, pn);
+        bip_ipn_set64(mmie->sequence_number, pn64);
 
         bip_aad(skb, aad);
 
         /*
          * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
          */
-        ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf,
-                           aad, skb->data + 24, skb->len - 24, mmie->mic);
+        ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
+                           skb->data + 24, skb->len - 24, mmie->mic);
 
         return TX_CONTINUE;
 }
@@ -609,8 +614,7 @@ ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
         if (!(status->flag & RX_FLAG_DECRYPTED)) {
                 /* hardware didn't decrypt/verify MIC */
                 bip_aad(skb, aad);
-                ieee80211_aes_cmac(key->u.aes_cmac.tfm,
-                                   key->u.aes_cmac.rx_crypto_buf, aad,
+                ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
                                    skb->data + 24, skb->len - 24, mic);
                 if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
                         key->u.aes_cmac.icverrors++;