[4/6] mac80211: Send control port frames over nl80211

Commit Message

Denis Kenzior Jan. 31, 2018, 9:33 p.m. UTC

If userspace requested control port frames to go over 80211, then do so.
The control packets are intercepted just prior to delivery of the packet
to the underlying network device.

Pre-authentication type frames (protocol: 0x88c7) are also forwarded
over nl80211.

Signed-off-by: Denis Kenzior <[e-mail]>
---
 net/mac80211/cfg.c         |  2 ++
 net/mac80211/ieee80211_i.h |  1 +
 net/mac80211/mlme.c        |  2 ++
 net/mac80211/rx.c          | 34 +++++++++++++++++++++++++++++-----
 4 files changed, 34 insertions(+), 5 deletions(-)

Comments

Johannes Berg Jan. 31, 2018, 9:50 p.m. UTC | #1

On Wed, 2018-01-31 at 15:33 -0600, Denis Kenzior wrote:
> 
> +		if (!cfg80211_rx_control_port(dev, skb->data, skb->len,
> +					      ehdr->h_source,
> +					      be16_to_cpu(skb->protocol),
> +					      noencrypt))
> +			dev_kfree_skb(skb);

Err, you should free it unconditionally, no? You don't do anything with
the skb afterwards, since you can't get into the else branch and
deliver it to the netdev now, so afaict it'd be leaked if not freed?

Which explains why you didn't notice the error in the previous patch,
it was making this code correct by freeing it all the time (never
hitting an error, presumably, and even if you wouldn't notice the small
leaks)

johannes

Patch

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 46028e12e216..f53bfb27295f 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -925,6 +925,7 @@  static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
 	 */
 	sdata->control_port_protocol = params->crypto.control_port_ethertype;
 	sdata->control_port_no_encrypt = params->crypto.control_port_no_encrypt;
+	sdata->control_port_over_nl80211 = false;
 	sdata->encrypt_headroom = ieee80211_cs_headroom(sdata->local,
 							&params->crypto,
 							sdata->vif.type);
@@ -934,6 +935,7 @@  static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
 			params->crypto.control_port_ethertype;
 		vlan->control_port_no_encrypt =
 			params->crypto.control_port_no_encrypt;
+		vlan->control_port_over_nl80211 = false;
 		vlan->encrypt_headroom =
 			ieee80211_cs_headroom(sdata->local,
 					      &params->crypto,
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 26900025de2f..6f91aea6a4cb 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -899,6 +899,7 @@  struct ieee80211_sub_if_data {
 	u16 sequence_number;
 	__be16 control_port_protocol;
 	bool control_port_no_encrypt;
+	bool control_port_over_nl80211;
 	int encrypt_headroom;
 
 	atomic_t num_tx_queued;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 39b660b9a908..fc71a906939b 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -4830,6 +4830,8 @@  int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 
 	sdata->control_port_protocol = req->crypto.control_port_ethertype;
 	sdata->control_port_no_encrypt = req->crypto.control_port_no_encrypt;
+	sdata->control_port_over_nl80211 =
+					req->crypto.control_port_over_nl80211;
 	sdata->encrypt_headroom = ieee80211_cs_headroom(local, &req->crypto,
 							sdata->vif.type);
 
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index e755f93ad735..c3abf9e44079 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2243,6 +2243,33 @@  static bool ieee80211_frame_allowed(struct ieee80211_rx_data *rx, __le16 fc)
 	return true;
 }
 
+static void ieee80211_deliver_skb_to_local_stack(struct sk_buff *skb,
+						 struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_sub_if_data *sdata = rx->sdata;
+	struct net_device *dev = sdata->dev;
+
+	if (unlikely((skb->protocol == sdata->control_port_protocol ||
+		      skb->protocol == cpu_to_be16(ETH_P_PREAUTH)) &&
+		     sdata->control_port_over_nl80211)) {
+		struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
+		bool noencrypt = status->flag & RX_FLAG_DECRYPTED;
+		struct ethhdr *ehdr = eth_hdr(skb);
+
+		if (!cfg80211_rx_control_port(dev, skb->data, skb->len,
+					      ehdr->h_source,
+					      be16_to_cpu(skb->protocol),
+					      noencrypt))
+			dev_kfree_skb(skb);
+	} else {
+		/* deliver to local stack */
+		if (rx->napi)
+			napi_gro_receive(rx->napi, skb);
+		else
+			netif_receive_skb(skb);
+	}
+}
+
 /*
  * requires that rx->skb is a frame with ethernet header
  */
@@ -2327,13 +2354,10 @@  ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
 #endif
 
 	if (skb) {
-		/* deliver to local stack */
 		skb->protocol = eth_type_trans(skb, dev);
 		memset(skb->cb, 0, sizeof(skb->cb));
-		if (rx->napi)
-			napi_gro_receive(rx->napi, skb);
-		else
-			netif_receive_skb(skb);
+
+		ieee80211_deliver_skb_to_local_stack(skb, rx);
 	}
 
 	if (xmit_skb) {