mac80211: support paged rx SKBs

Mac80211 drivers can now pass paged SKBs to mac80211 via
ieee80211_rx{_irqsafe}. The implementation currently use
skb_linearize() in a few places i.e. management frame
handling, software decryption, defragmentation and A-MSDU
process. We will optimize them one by one later.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Cc: Kalle Valo <kalle.valo@iki.fi>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 32 insertions, 4 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 1da57c8e849..11ed5aa90f8 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -38,7 +38,7 @@ static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
 {
         if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
                 if (likely(skb->len > FCS_LEN))
-                        skb_trim(skb, skb->len - FCS_LEN);
+                        __pskb_trim(skb, skb->len - FCS_LEN);
                 else {
                         /* driver bug */
                         WARN_ON(1);
@@ -227,6 +227,12 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
         if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
                 present_fcs_len = FCS_LEN;
 
+        /* make sure hdr->frame_control is on the linear part */
+        if (!pskb_may_pull(origskb, 2)) {
+                dev_kfree_skb(origskb);
+                return NULL;
+        }
+
         if (!local->monitors) {
                 if (should_drop_frame(origskb, present_fcs_len)) {
                         dev_kfree_skb(origskb);
@@ -931,6 +937,9 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
                 return RX_DROP_MONITOR;
         }
 
+        if (skb_linearize(rx->skb))
+                return RX_DROP_UNUSABLE;
+
         /* Check for weak IVs if possible */
         if (rx->sta && rx->key->conf.alg == ALG_WEP &&
             ieee80211_is_data(hdr->frame_control) &&
@@ -1231,6 +1240,9 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
         }
         I802_DEBUG_INC(rx->local->rx_handlers_fragments);
 
+        if (skb_linearize(rx->skb))
+                return RX_DROP_UNUSABLE;
+
         seq = (sc & IEEE80211_SCTL_SEQ) >> 4;
 
         if (frag == 0) {
@@ -1588,6 +1600,9 @@ ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
         skb->dev = dev;
         __skb_queue_head_init(&frame_list);
 
+        if (skb_linearize(skb))
+                return RX_DROP_UNUSABLE;
+
         ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr,
                                  rx->sdata->vif.type,
                                  rx->local->hw.extra_tx_headroom);
@@ -2357,29 +2372,42 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
         struct ieee80211_local *local = hw_to_local(hw);
         struct ieee80211_sub_if_data *sdata;
         struct ieee80211_hdr *hdr;
+        __le16 fc;
         struct ieee80211_rx_data rx;
         int prepares;
         struct ieee80211_sub_if_data *prev = NULL;
         struct sk_buff *skb_new;
         struct sta_info *sta, *tmp;
         bool found_sta = false;
+        int err = 0;
 
-        hdr = (struct ieee80211_hdr *)skb->data;
+        fc = ((struct ieee80211_hdr *)skb->data)->frame_control;
         memset(&rx, 0, sizeof(rx));
         rx.skb = skb;
         rx.local = local;
 
-        if (ieee80211_is_data(hdr->frame_control) || ieee80211_is_mgmt(hdr->frame_control))
+        if (ieee80211_is_data(fc) || ieee80211_is_mgmt(fc))
                 local->dot11ReceivedFragmentCount++;
 
         if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning) ||
                      test_bit(SCAN_OFF_CHANNEL, &local->scanning)))
                 rx.flags |= IEEE80211_RX_IN_SCAN;
 
+        if (ieee80211_is_mgmt(fc))
+                err = skb_linearize(skb);
+        else
+                err = !pskb_may_pull(skb, ieee80211_hdrlen(fc));
+
+        if (err) {
+                dev_kfree_skb(skb);
+                return;
+        }
+
+        hdr = (struct ieee80211_hdr *)skb->data;
         ieee80211_parse_qos(&rx);
         ieee80211_verify_alignment(&rx);
 
-        if (ieee80211_is_data(hdr->frame_control)) {
+        if (ieee80211_is_data(fc)) {
                 for_each_sta_info(local, hdr->addr2, sta, tmp) {
                         rx.sta = sta;
                         found_sta = true;