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>

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 1a8f50a..ecaae10 100644 (file)
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1822,7 +1822,10 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw);
  * ieee80211_rx - receive frame
  *
  * Use this function to hand received frames to mac80211. The receive
- * buffer in @skb must start with an IEEE 802.11 header.
+ * buffer in @skb must start with an IEEE 802.11 header. In case of a
+ * paged @skb is used, the driver is recommended to put the ieee80211
+ * header of the frame on the linear part of the @skb to avoid memory
+ * allocation and/or memcpy by the stack.
  *
  * This function may not be called in IRQ context. Calls to this function
  * for a single hardware must be synchronized against each other. Calls to

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 1da57c8..11ed5aa 100644 (file)
--- 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;

diff --git a/net/wireless/util.c b/net/wireless/util.c
index be2ab8c..7acb81b 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -330,11 +330,18 @@ int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
                if (iftype == NL80211_IFTYPE_MESH_POINT) {
                        struct ieee80211s_hdr *meshdr =
                                (struct ieee80211s_hdr *) (skb->data + hdrlen);
-                       hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
+                       /* make sure meshdr->flags is on the linear part */
+                       if (!pskb_may_pull(skb, hdrlen + 1))
+                               return -1;
                        if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
-                               memcpy(dst, meshdr->eaddr1, ETH_ALEN);
-                               memcpy(src, meshdr->eaddr2, ETH_ALEN);
+                               skb_copy_bits(skb, hdrlen +
+                                       offsetof(struct ieee80211s_hdr, eaddr1),
+                                       dst, ETH_ALEN);
+                               skb_copy_bits(skb, hdrlen +
+                                       offsetof(struct ieee80211s_hdr, eaddr2),
+                                       src, ETH_ALEN);
                        }
+                       hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
                }
                break;
        case cpu_to_le16(IEEE80211_FCTL_FROMDS):
@@ -346,9 +353,14 @@ int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
                if (iftype == NL80211_IFTYPE_MESH_POINT) {
                        struct ieee80211s_hdr *meshdr =
                                (struct ieee80211s_hdr *) (skb->data + hdrlen);
-                       hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
+                       /* make sure meshdr->flags is on the linear part */
+                       if (!pskb_may_pull(skb, hdrlen + 1))
+                               return -1;
                        if (meshdr->flags & MESH_FLAGS_AE_A4)
-                               memcpy(src, meshdr->eaddr1, ETH_ALEN);
+                               skb_copy_bits(skb, hdrlen +
+                                       offsetof(struct ieee80211s_hdr, eaddr1),
+                                       src, ETH_ALEN);
+                       hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
                }
                break;
        case cpu_to_le16(0):
@@ -357,7 +369,7 @@ int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
                break;
        }
 
-       if (unlikely(skb->len - hdrlen < 8))
+       if (!pskb_may_pull(skb, hdrlen + 8))
                return -1;
 
        payload = skb->data + hdrlen;