mac80211: factor out station lookup from ieee80211_build_hdr()

In order to look up the RA station earlier to implement a TX
fastpath, factor out the lookup from ieee80211_build_hdr().
To always have a valid station pointer, also move some of the
checks into the new function.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 118 insertions, 70 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 018f029d0c95..e5d679f38cc1 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1789,6 +1789,91 @@ fail:
         return NETDEV_TX_OK; /* meaning, we dealt with the skb */
 }
 
+static inline bool ieee80211_is_tdls_setup(struct sk_buff *skb)
+{
+        u16 ethertype = (skb->data[12] << 8) | skb->data[13];
+
+        return ethertype == ETH_P_TDLS &&
+               skb->len > 14 &&
+               skb->data[14] == WLAN_TDLS_SNAP_RFTYPE;
+}
+
+static int ieee80211_lookup_ra_sta(struct ieee80211_sub_if_data *sdata,
+                                   struct sk_buff *skb,
+                                   struct sta_info **sta_out)
+{
+        struct sta_info *sta;
+
+        switch (sdata->vif.type) {
+        case NL80211_IFTYPE_AP_VLAN:
+                sta = rcu_dereference(sdata->u.vlan.sta);
+                if (sta) {
+                        *sta_out = sta;
+                        return 0;
+                } else if (sdata->wdev.use_4addr) {
+                        return -ENOLINK;
+                }
+                /* fall through */
+        case NL80211_IFTYPE_AP:
+        case NL80211_IFTYPE_OCB:
+        case NL80211_IFTYPE_ADHOC:
+                if (is_multicast_ether_addr(skb->data)) {
+                        *sta_out = ERR_PTR(-ENOENT);
+                        return 0;
+                }
+                sta = sta_info_get_bss(sdata, skb->data);
+                break;
+        case NL80211_IFTYPE_WDS:
+                sta = sta_info_get(sdata, sdata->u.wds.remote_addr);
+                break;
+#ifdef CONFIG_MAC80211_MESH
+        case NL80211_IFTYPE_MESH_POINT:
+                /* determined much later */
+                *sta_out = NULL;
+                return 0;
+#endif
+        case NL80211_IFTYPE_STATION:
+                if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) {
+                        sta = sta_info_get(sdata, skb->data);
+                        if (sta) {
+                                bool tdls_peer, tdls_auth;
+
+                                tdls_peer = test_sta_flag(sta,
+                                                          WLAN_STA_TDLS_PEER);
+                                tdls_auth = test_sta_flag(sta,
+                                                WLAN_STA_TDLS_PEER_AUTH);
+
+                                if (tdls_peer && tdls_auth) {
+                                        *sta_out = sta;
+                                        return 0;
+                                }
+
+                                /*
+                                 * TDLS link during setup - throw out frames to
+                                 * peer. Allow TDLS-setup frames to unauthorized
+                                 * peers for the special case of a link teardown
+                                 * after a TDLS sta is removed due to being
+                                 * unreachable.
+                                 */
+                                if (tdls_peer && !tdls_auth &&
+                                    !ieee80211_is_tdls_setup(skb))
+                                        return -EINVAL;
+                        }
+
+                }
+
+                sta = sta_info_get(sdata, sdata->u.mgd.bssid);
+                if (!sta)
+                        return -ENOLINK;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        *sta_out = sta ?: ERR_PTR(-ENOENT);
+        return 0;
+}
+
 /**
  * ieee80211_build_hdr - build 802.11 header in the given frame
  * @sdata: virtual interface to build the header for
@@ -1809,7 +1894,7 @@ fail:
  */
 static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                                            struct sk_buff *skb, u32 info_flags,
-                                           struct sta_info **sta_out)
+                                           struct sta_info *sta)
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_tx_info *info;
@@ -1822,17 +1907,18 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
         const u8 *encaps_data;
         int encaps_len, skip_header_bytes;
         int nh_pos, h_pos;
-        struct sta_info *sta = NULL;
-        bool wme_sta = false, authorized = false, tdls_auth = false;
-        bool tdls_peer = false, tdls_setup_frame = false;
+        bool wme_sta = false, authorized = false;
+        bool tdls_peer;
         bool multicast;
-        bool have_station = false;
         u16 info_id = 0;
         struct ieee80211_chanctx_conf *chanctx_conf;
         struct ieee80211_sub_if_data *ap_sdata;
         enum ieee80211_band band;
         int ret;
 
+        if (IS_ERR(sta))
+                sta = NULL;
+
         /* convert Ethernet header to proper 802.11 header (based on
          * operation mode) */
         ethertype = (skb->data[12] << 8) | skb->data[13];
@@ -1840,8 +1926,7 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
 
         switch (sdata->vif.type) {
         case NL80211_IFTYPE_AP_VLAN:
-                sta = rcu_dereference(sdata->u.vlan.sta);
-                if (sta) {
+                if (sdata->wdev.use_4addr) {
                         fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS);
                         /* RA TA DA SA */
                         memcpy(hdr.addr1, sta->sta.addr, ETH_ALEN);
@@ -1851,11 +1936,6 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                         hdrlen = 30;
                         authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED);
                         wme_sta = sta->sta.wme;
-                        have_station = true;
-                        *sta_out = sta;
-                } else if (sdata->wdev.use_4addr) {
-                        ret = -ENOLINK;
-                        goto free;
                 }
                 ap_sdata = container_of(sdata->bss, struct ieee80211_sub_if_data,
                                         u.ap);
@@ -1865,7 +1945,7 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                         goto free;
                 }
                 band = chanctx_conf->def.chan->band;
-                if (sta)
+                if (sdata->wdev.use_4addr)
                         break;
                 /* fall through */
         case NL80211_IFTYPE_AP:
@@ -1969,44 +2049,15 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                 break;
 #endif
         case NL80211_IFTYPE_STATION:
-                if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) {
-                        sta = sta_info_get(sdata, skb->data);
-                        if (sta) {
-                                tdls_peer = test_sta_flag(sta,
-                                                          WLAN_STA_TDLS_PEER);
-                                tdls_auth = test_sta_flag(sta,
-                                                WLAN_STA_TDLS_PEER_AUTH);
-                        }
-
-                        if (tdls_peer)
-                                tdls_setup_frame =
-                                        ethertype == ETH_P_TDLS &&
-                                        skb->len > 14 &&
-                                        skb->data[14] == WLAN_TDLS_SNAP_RFTYPE;
-                }
-
-                /*
-                 * TDLS link during setup - throw out frames to peer. We allow
-                 * TDLS-setup frames to unauthorized peers for the special case
-                 * of a link teardown after a TDLS sta is removed due to being
-                 * unreachable.
-                 */
-                if (tdls_peer && !tdls_auth && !tdls_setup_frame) {
-                        ret = -EINVAL;
-                        goto free;
-                }
+                /* we already did checks when looking up the RA STA */
+                tdls_peer = test_sta_flag(sta, WLAN_STA_TDLS_PEER);
 
-                /* send direct packets to authorized TDLS peers */
-                if (tdls_peer && tdls_auth) {
+                if (tdls_peer) {
                         /* DA SA BSSID */
                         memcpy(hdr.addr1, skb->data, ETH_ALEN);
                         memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
                         memcpy(hdr.addr3, sdata->u.mgd.bssid, ETH_ALEN);
                         hdrlen = 24;
-                        have_station = true;
-                        authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED);
-                        wme_sta = sta->sta.wme;
-                        *sta_out = sta;
                 }  else if (sdata->u.mgd.use_4addr &&
                             cpu_to_be16(ethertype) != sdata->control_port_protocol) {
                         fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS |
@@ -2063,30 +2114,16 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                 goto free;
         }
 
-        /*
-         * There's no need to try to look up the destination station
-         * if it is a multicast address. In mesh, there's no need to
-         * look up the station at all as it always must be QoS capable
-         * and mesh mode checks authorization later.
-         */
         multicast = is_multicast_ether_addr(hdr.addr1);
-        if (multicast) {
-                *sta_out = ERR_PTR(-ENOENT);
-        } else if (!have_station && !ieee80211_vif_is_mesh(&sdata->vif)) {
-                if (sdata->control_port_protocol == skb->protocol)
-                        sta = sta_info_get_bss(sdata, hdr.addr1);
-                else
-                        sta = sta_info_get(sdata, hdr.addr1);
-                if (sta) {
-                        authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED);
-                        wme_sta = sta->sta.wme;
-                }
-                *sta_out = sta ?: ERR_PTR(-ENOENT);
-        }
 
-        /* For mesh, the use of the QoS header is mandatory */
-        if (ieee80211_vif_is_mesh(&sdata->vif))
+        /* sta is always NULL for mesh */
+        if (sta) {
+                authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED);
+                wme_sta = sta->sta.wme;
+        } else if (ieee80211_vif_is_mesh(&sdata->vif)) {
+                /* For mesh, the use of the QoS header is mandatory */
                 wme_sta = true;
+        }
 
         /* receiver does QoS (which also means we do) use it */
         if (wme_sta) {
@@ -2259,7 +2296,7 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                                   u32 info_flags)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
-        struct sta_info *sta = NULL;
+        struct sta_info *sta;
 
         if (unlikely(skb->len < ETH_HLEN)) {
                 kfree_skb(skb);
@@ -2268,7 +2305,12 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 
         rcu_read_lock();
 
-        skb = ieee80211_build_hdr(sdata, skb, info_flags, &sta);
+        if (ieee80211_lookup_ra_sta(sdata, skb, &sta)) {
+                kfree_skb(skb);
+                goto out;
+        }
+
+        skb = ieee80211_build_hdr(sdata, skb, info_flags, sta);
         if (IS_ERR(skb))
                 goto out;
 
@@ -2304,11 +2346,17 @@ ieee80211_build_data_template(struct ieee80211_sub_if_data *sdata,
                 .local = sdata->local,
                 .sdata = sdata,
         };
-        struct sta_info *sta_ignore;
+        struct sta_info *sta;
 
         rcu_read_lock();
 
-        skb = ieee80211_build_hdr(sdata, skb, info_flags, &sta_ignore);
+        if (ieee80211_lookup_ra_sta(sdata, skb, &sta)) {
+                kfree_skb(skb);
+                skb = ERR_PTR(-EINVAL);
+                goto out;
+        }
+
+        skb = ieee80211_build_hdr(sdata, skb, info_flags, sta);
         if (IS_ERR(skb))
                 goto out;