3 files changed, 95 insertions, 70 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index baa1be0671e5..dac44cbd036f 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1215,6 +1215,45 @@ retry:
 
 /* device xmit handlers */
 
+static int ieee80211_skb_resize(struct ieee80211_local *local,
+                                struct sk_buff *skb,
+                                int head_need, bool may_encrypt)
+{
+        int tail_need = 0;
+
+        /*
+         * This could be optimised, devices that do full hardware
+         * crypto (including TKIP MMIC) need no tailroom... But we
+         * have no drivers for such devices currently.
+         */
+        if (may_encrypt) {
+                tail_need = IEEE80211_ENCRYPT_TAILROOM;
+                tail_need -= skb_tailroom(skb);
+                tail_need = max_t(int, tail_need, 0);
+        }
+
+        if (head_need || tail_need) {
+                /* Sorry. Can't account for this any more */
+                skb_orphan(skb);
+        }
+
+        if (skb_header_cloned(skb))
+                I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
+        else
+                I802_DEBUG_INC(local->tx_expand_skb_head);
+
+        if (pskb_expand_head(skb, head_need, tail_need, GFP_ATOMIC)) {
+                printk(KERN_DEBUG "%s: failed to reallocate TX buffer\n",
+                       wiphy_name(local->hw.wiphy));
+                return -ENOMEM;
+        }
+
+        /* update truesize too */
+        skb->truesize += head_need + tail_need;
+
+        return 0;
+}
+
 int ieee80211_master_start_xmit(struct sk_buff *skb,
                                 struct net_device *dev)
 {
@@ -1222,6 +1261,7 @@ int ieee80211_master_start_xmit(struct sk_buff *skb,
         struct net_device *odev = NULL;
         struct ieee80211_sub_if_data *osdata;
         int headroom;
+        bool may_encrypt;
         int ret;
 
         if (info->control.ifindex)
@@ -1241,13 +1281,18 @@ int ieee80211_master_start_xmit(struct sk_buff *skb,
 
         osdata = IEEE80211_DEV_TO_SUB_IF(odev);
 
-        headroom = osdata->local->tx_headroom + IEEE80211_ENCRYPT_HEADROOM;
-        if (skb_headroom(skb) < headroom) {
-                if (pskb_expand_head(skb, headroom, 0, GFP_ATOMIC)) {
-                        dev_kfree_skb(skb);
-                        dev_put(odev);
-                        return 0;
-                }
+        may_encrypt = !(info->flags & IEEE80211_TX_CTL_DO_NOT_ENCRYPT);
+
+        headroom = osdata->local->tx_headroom;
+        if (may_encrypt)
+                headroom += IEEE80211_ENCRYPT_HEADROOM;
+        headroom -= skb_headroom(skb);
+        headroom = max_t(int, 0, headroom);
+
+        if (ieee80211_skb_resize(osdata->local, skb, headroom, may_encrypt)) {
+                dev_kfree_skb(skb);
+                dev_put(odev);
+                return 0;
         }
 
         info->control.vif = &osdata->vif;
@@ -1509,32 +1554,26 @@ int ieee80211_subif_start_xmit(struct sk_buff *skb,
          * build in headroom in __dev_alloc_skb() (linux/skbuff.h) and
          * alloc_skb() (net/core/skbuff.c)
          */
-        head_need = hdrlen + encaps_len + meshhdrlen + local->tx_headroom;
-        head_need -= skb_headroom(skb);
+        head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb);
 
-        /* We are going to modify skb data, so make a copy of it if happens to
-         * be cloned. This could happen, e.g., with Linux bridge code passing
-         * us broadcast frames. */
+        /*
+         * So we need to modify the skb header and hence need a copy of
+         * that. The head_need variable above doesn't, so far, include
+         * the needed header space that we don't need right away. If we
+         * can, then we don't reallocate right now but only after the
+         * frame arrives at the master device (if it does...)
+         *
+         * If we cannot, however, then we will reallocate to include all
+         * the ever needed space. Also, if we need to reallocate it anyway,
+         * make it big enough for everything we may ever need.
+         */
 
         if (head_need > 0 || skb_header_cloned(skb)) {
-#if 0
-                printk(KERN_DEBUG "%s: need to reallocate buffer for %d bytes "
-                       "of headroom\n", dev->name, head_need);
-#endif
-
-                if (skb_header_cloned(skb))
-                        I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
-                else
-                        I802_DEBUG_INC(local->tx_expand_skb_head);
-                /* Since we have to reallocate the buffer, make sure that there
-                 * is enough room for possible WEP IV/ICV and TKIP (8 bytes
-                 * before payload and 12 after). */
-                if (pskb_expand_head(skb, (head_need > 0 ? head_need + 8 : 8),
-                                     12, GFP_ATOMIC)) {
-                        printk(KERN_DEBUG "%s: failed to reallocate TX buffer"
-                               "\n", dev->name);
+                head_need += IEEE80211_ENCRYPT_HEADROOM;
+                head_need += local->tx_headroom;
+                head_need = max_t(int, 0, head_need);
+                if (ieee80211_skb_resize(local, skb, head_need, true))
                         goto fail;
-                }
         }
 
         if (encaps_data) {
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
index 1e7f03dd8f6b..c9fd1291b19d 100644
--- a/net/mac80211/wep.c
+++ b/net/mac80211/wep.c
@@ -93,13 +93,9 @@ static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
         fc |= IEEE80211_FCTL_PROTECTED;
         hdr->frame_control = cpu_to_le16(fc);
 
-        if ((skb_headroom(skb) < WEP_IV_LEN ||
-             skb_tailroom(skb) < WEP_ICV_LEN)) {
-                I802_DEBUG_INC(local->tx_expand_skb_head);
-                if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN,
-                                              GFP_ATOMIC)))
-                        return NULL;
-        }
+        if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN ||
+                    skb_headroom(skb) < WEP_IV_LEN))
+                return NULL;
 
         hdrlen = ieee80211_get_hdrlen(fc);
         newhdr = skb_push(skb, WEP_IV_LEN);
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index d6635f6e5618..9f6fd20374e1 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -79,6 +79,7 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
         struct sk_buff *skb = tx->skb;
         int authenticator;
         int wpa_test = 0;
+        int tail;
 
         fc = tx->fc;
 
@@ -98,16 +99,13 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
                 return TX_CONTINUE;
         }
 
-        if (skb_tailroom(skb) < MICHAEL_MIC_LEN) {
-                I802_DEBUG_INC(tx->local->tx_expand_skb_head);
-                if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN,
-                                              MICHAEL_MIC_LEN + TKIP_ICV_LEN,
-                                              GFP_ATOMIC))) {
-                        printk(KERN_DEBUG "%s: failed to allocate more memory "
-                               "for Michael MIC\n", tx->dev->name);
-                        return TX_DROP;
-                }
-        }
+        tail = MICHAEL_MIC_LEN;
+        if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
+                tail += TKIP_ICV_LEN;
+
+        if (WARN_ON(skb_tailroom(skb) < tail ||
+                    skb_headroom(skb) < TKIP_IV_LEN))
+                return TX_DROP;
 
 #if 0
         authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
@@ -188,7 +186,7 @@ static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
         struct ieee80211_key *key = tx->key;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-        int hdrlen, len, tailneed;
+        int hdrlen, len, tail;
         u16 fc;
         u8 *pos;
 
@@ -199,7 +197,7 @@ static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
             !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
                 /* hwaccel - with no need for preallocated room for IV/ICV */
                 info->control.hw_key = &tx->key->conf;
-                return TX_CONTINUE;
+                return 0;
         }
 
         fc = le16_to_cpu(hdr->frame_control);
@@ -207,17 +205,13 @@ static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         len = skb->len - hdrlen;
 
         if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
-                tailneed = 0;
+                tail = 0;
         else
-                tailneed = TKIP_ICV_LEN;
-
-        if ((skb_headroom(skb) < TKIP_IV_LEN ||
-             skb_tailroom(skb) < tailneed)) {
-                I802_DEBUG_INC(tx->local->tx_expand_skb_head);
-                if (unlikely(pskb_expand_head(skb, TKIP_IV_LEN, tailneed,
-                                              GFP_ATOMIC)))
-                        return -1;
-        }
+                tail = TKIP_ICV_LEN;
+
+        if (WARN_ON(skb_tailroom(skb) < tail ||
+                    skb_headroom(skb) < TKIP_IV_LEN))
+                return -1;
 
         pos = skb_push(skb, TKIP_IV_LEN);
         memmove(pos, pos + TKIP_IV_LEN, hdrlen);
@@ -432,7 +426,7 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
         struct ieee80211_key *key = tx->key;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-        int hdrlen, len, tailneed;
+        int hdrlen, len, tail;
         u16 fc;
         u8 *pos, *pn, *b_0, *aad, *scratch;
         int i;
@@ -445,7 +439,7 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
                 /* hwaccel - with no need for preallocated room for CCMP "
                  * header or MIC fields */
                 info->control.hw_key = &tx->key->conf;
-                return TX_CONTINUE;
+                return 0;
         }
 
         scratch = key->u.ccmp.tx_crypto_buf;
@@ -457,17 +451,13 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         len = skb->len - hdrlen;
 
         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
-                tailneed = 0;
+                tail = 0;
         else
-                tailneed = CCMP_MIC_LEN;
-
-        if ((skb_headroom(skb) < CCMP_HDR_LEN ||
-             skb_tailroom(skb) < tailneed)) {
-                I802_DEBUG_INC(tx->local->tx_expand_skb_head);
-                if (unlikely(pskb_expand_head(skb, CCMP_HDR_LEN, tailneed,
-                                              GFP_ATOMIC)))
-                        return -1;
-        }
+                tail = CCMP_MIC_LEN;
+
+        if (WARN_ON(skb_tailroom(skb) < tail ||
+                    skb_headroom(skb) < CCMP_HDR_LEN))
+                return -1;
 
         pos = skb_push(skb, CCMP_HDR_LEN);
         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);