mac80211: linearize SKBs as needed for crypto

Not linearizing every SKB will help actually pass
non-linear SKBs all the way up when on an encrypted
connection. For now, linearize TKIP completely as
it is lower performance and I don't quite grok all
the details.

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

3 files changed, 31 insertions, 8 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index b38da13e2a88..53c88d145472 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1063,10 +1063,6 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                 return RX_DROP_MONITOR;
         }
 
-        if (skb_linearize(rx->skb))
-                return RX_DROP_UNUSABLE;
-        /* the hdr variable is invalid now! */
-
         switch (rx->key->conf.cipher) {
         case WLAN_CIPHER_SUITE_WEP40:
         case WLAN_CIPHER_SUITE_WEP104:
@@ -1089,6 +1085,8 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                 return RX_DROP_UNUSABLE;
         }
 
+        /* the hdr variable is invalid after the decrypt handlers */
+
         /* either the frame has been decrypted or will be dropped */
         status->flag |= RX_FLAG_DECRYPTED;
 
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
index 5cd87ba11bb7..7aa31bbfaa3b 100644
--- a/net/mac80211/wep.c
+++ b/net/mac80211/wep.c
@@ -284,22 +284,27 @@ ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
         struct sk_buff *skb = rx->skb;
         struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+        __le16 fc = hdr->frame_control;
 
-        if (!ieee80211_is_data(hdr->frame_control) &&
-            !ieee80211_is_auth(hdr->frame_control))
+        if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc))
                 return RX_CONTINUE;
 
         if (!(status->flag & RX_FLAG_DECRYPTED)) {
+                if (skb_linearize(rx->skb))
+                        return RX_DROP_UNUSABLE;
                 if (rx->sta && ieee80211_wep_is_weak_iv(rx->skb, rx->key))
                         rx->sta->wep_weak_iv_count++;
                 if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
                         return RX_DROP_UNUSABLE;
         } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
+                if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) + WEP_IV_LEN))
+                        return RX_DROP_UNUSABLE;
                 if (rx->sta && ieee80211_wep_is_weak_iv(rx->skb, rx->key))
                         rx->sta->wep_weak_iv_count++;
                 ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
                 /* remove ICV */
-                skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
+                if (pskb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN))
+                        return RX_DROP_UNUSABLE;
         }
 
         return RX_CONTINUE;
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index b758350919ff..0ae23c60968c 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -138,6 +138,10 @@ ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
         if (skb->len < hdrlen + MICHAEL_MIC_LEN)
                 return RX_DROP_UNUSABLE;
 
+        if (skb_linearize(rx->skb))
+                return RX_DROP_UNUSABLE;
+        hdr = (void *)skb->data;
+
         data = skb->data + hdrlen;
         data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
         key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
@@ -253,6 +257,11 @@ ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
         if (!rx->sta || skb->len - hdrlen < 12)
                 return RX_DROP_UNUSABLE;
 
+        /* it may be possible to optimize this a bit more */
+        if (skb_linearize(rx->skb))
+                return RX_DROP_UNUSABLE;
+        hdr = (void *)skb->data;
+
         /*
          * Let TKIP code verify IV, but skip decryption.
          * In the case where hardware checks the IV as well,
@@ -484,6 +493,14 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
         if (!rx->sta || data_len < 0)
                 return RX_DROP_UNUSABLE;
 
+        if (status->flag & RX_FLAG_DECRYPTED) {
+                if (!pskb_may_pull(rx->skb, hdrlen + CCMP_HDR_LEN))
+                        return RX_DROP_UNUSABLE;
+        } else {
+                if (skb_linearize(rx->skb))
+                        return RX_DROP_UNUSABLE;
+        }
+
         ccmp_hdr2pn(pn, skb->data + hdrlen);
 
         queue = rx->security_idx;
@@ -509,7 +526,8 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
         memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);
 
         /* Remove CCMP header and MIC */
-        skb_trim(skb, skb->len - CCMP_MIC_LEN);
+        if (pskb_trim(skb, skb->len - CCMP_MIC_LEN))
+                return RX_DROP_UNUSABLE;
         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
         skb_pull(skb, CCMP_HDR_LEN);
 
@@ -609,6 +627,8 @@ ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
         if (!ieee80211_is_mgmt(hdr->frame_control))
                 return RX_CONTINUE;
 
+        /* management frames are already linear */
+
         if (skb->len < 24 + sizeof(*mmie))
                 return RX_DROP_UNUSABLE;