nl80211: add src and dst addr attributes for control port tx/rx

When using control port over nl80211 in AP mode with
pre-authentication, APs need to forward frames to other
APs defined by their MAC address. Before this patch,
pre-auth frames reaching user space over nl80211 control
port  have no longer any information about the dest attached,
which can be used for forwarding to a controller or injecting
the frame back to a ethernet interface over a AF_PACKET
socket.
Analog problems exist, when forwarding pre-auth frames from
AP -> STA.

This patch therefore adds the NL80211_ATTR_DST_MAC and
NL80211_ATTR_SRC_MAC attributes to provide more context
information when forwarding.
The respective arguments are optional on tx and included on rx.
Therefore unaware existing software is not affected.

Software which wants to detect this feature, can do so
by checking against:
  NL80211_EXT_FEATURE_CONTROL_PORT_OVER_NL80211_MAC_ADDRS

Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Link: https://lore.kernel.org/r/20200115125522.3755-1-markus.theil@tu-ilmenau.de
[split into separate cfg80211/mac80211 patches]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 36 insertions, 17 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 4c0ea54e0f59..33fe6ac1c242 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -633,6 +633,8 @@ const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[NL80211_ATTR_HE_OBSS_PD] = NLA_POLICY_NESTED(he_obss_pd_policy),
 	[NL80211_ATTR_VLAN_ID] = NLA_POLICY_RANGE(NLA_U16, 1, VLAN_N_VID - 2),
 	[NL80211_ATTR_HE_BSS_COLOR] = NLA_POLICY_NESTED(he_bss_color_policy),
+	[NL80211_ATTR_SRC_MAC] = NLA_POLICY_ETH_ADDR,
+	[NL80211_ATTR_DST_MAC] = NLA_POLICY_ETH_ADDR,
 };
 
 /* policy for the key attributes */
@@ -13694,6 +13696,7 @@ static int nl80211_tx_control_port(struct sk_buff *skb, struct genl_info *info)
 	const u8 *buf;
 	size_t len;
 	u8 *dest;
+	u8 src[ETH_ALEN];
 	u16 proto;
 	bool noencrypt;
 	int err;
@@ -13731,6 +13734,13 @@ static int nl80211_tx_control_port(struct sk_buff *skb, struct genl_info *info)
 		goto out;
 	}
 
+	/* copy src address under wdev_lock, as we may copy wdev_address */
+	if (info->attrs[NL80211_ATTR_SRC_MAC])
+		ether_addr_copy(src,
+				nla_data(info->attrs[NL80211_ATTR_SRC_MAC]));
+	else
+		ether_addr_copy(src, wdev_address(wdev));
+
 	wdev_unlock(wdev);
 
 	buf = nla_data(info->attrs[NL80211_ATTR_FRAME]);
@@ -13741,7 +13751,7 @@ static int nl80211_tx_control_port(struct sk_buff *skb, struct genl_info *info)
 		nla_get_flag(info->attrs[NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT]);
 
 	return rdev_tx_control_port(rdev, dev, buf, len,
-				    dest, cpu_to_be16(proto), noencrypt);
+				    dest, src, cpu_to_be16(proto), noencrypt);
 
  out:
 	wdev_unlock(wdev);
@@ -15996,7 +16006,8 @@ static int __nl80211_rx_control_port(struct net_device *dev,
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 	struct ethhdr *ehdr = eth_hdr(skb);
-	const u8 *addr = ehdr->h_source;
+	const u8 *daddr = ehdr->h_dest;
+	const u8 *saddr = ehdr->h_source;
 	u16 proto = be16_to_cpu(skb->protocol);
 	struct sk_buff *msg;
 	void *hdr;
@@ -16021,7 +16032,8 @@ static int __nl80211_rx_control_port(struct net_device *dev,
 	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, dev->ifindex) ||
 	    nla_put_u64_64bit(msg, NL80211_ATTR_WDEV, wdev_id(wdev),
 			      NL80211_ATTR_PAD) ||
-	    nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, addr) ||
+	    nla_put(msg, NL80211_ATTR_MAC, ETH_ALEN, saddr) ||
+	    nla_put(msg, NL80211_ATTR_DST_MAC, ETH_ALEN, daddr) ||
 	    nla_put_u16(msg, NL80211_ATTR_CONTROL_PORT_ETHERTYPE, proto) ||
 	    (unencrypted && nla_put_flag(msg,
 					 NL80211_ATTR_CONTROL_PORT_NO_ENCRYPT)))
diff --git a/net/wireless/rdev-ops.h b/net/wireless/rdev-ops.h
index e853a4fe6f97..39e6c1db3092 100644
--- a/net/wireless/rdev-ops.h
+++ b/net/wireless/rdev-ops.h
@@ -730,14 +730,14 @@ static inline int rdev_mgmt_tx(struct cfg80211_registered_device *rdev,
 static inline int rdev_tx_control_port(struct cfg80211_registered_device *rdev,
 				       struct net_device *dev,
 				       const void *buf, size_t len,
-				       const u8 *dest, __be16 proto,
-				       const bool noencrypt)
+				       const u8 *dest, const u8 *src,
+				       __be16 proto, const bool noencrypt)
 {
 	int ret;
 	trace_rdev_tx_control_port(&rdev->wiphy, dev, buf, len,
-				   dest, proto, noencrypt);
+				   dest, src, proto, noencrypt);
 	ret = rdev->ops->tx_control_port(&rdev->wiphy, dev, buf, len,
-					 dest, proto, noencrypt);
+					 dest, src, proto, noencrypt);
 	trace_rdev_return_int(&rdev->wiphy, ret);
 	return ret;
 }
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index d98ad2b3143b..fefa255fd062 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -1923,27 +1923,31 @@ TRACE_EVENT(rdev_mgmt_tx,
 
 TRACE_EVENT(rdev_tx_control_port,
 	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev,
-		 const u8 *buf, size_t len, const u8 *dest, __be16 proto,
+		 const u8 *buf, size_t len,
+		 const u8 *dest, const u8 *src, __be16 proto,
 		 bool unencrypted),
-	TP_ARGS(wiphy, netdev, buf, len, dest, proto, unencrypted),
+	TP_ARGS(wiphy, netdev, buf, len, dest, src, proto, unencrypted),
 	TP_STRUCT__entry(
 		WIPHY_ENTRY
 		NETDEV_ENTRY
 		MAC_ENTRY(dest)
-		__field(__be16, proto)
+		MAC_ENTRY(src)
+		__field(u16, proto)
 		__field(bool, unencrypted)
 	),
 	TP_fast_assign(
 		WIPHY_ASSIGN;
 		NETDEV_ASSIGN;
 		MAC_ASSIGN(dest, dest);
-		__entry->proto = proto;
+		MAC_ASSIGN(src, src);
+		__entry->proto = be16_to_cpu(proto);
 		__entry->unencrypted = unencrypted;
 	),
-	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", " MAC_PR_FMT ","
-		  " proto: 0x%x, unencrypted: %s",
-		  WIPHY_PR_ARG, NETDEV_PR_ARG, MAC_PR_ARG(dest),
-		  be16_to_cpu(__entry->proto),
+	TP_printk(WIPHY_PR_FMT ", " NETDEV_PR_FMT ", dest: " MAC_PR_FMT
+		  ", src: " MAC_PR_FMT ", proto: 0x%x, unencrypted: %s",
+		  WIPHY_PR_ARG, NETDEV_PR_ARG,
+		  MAC_PR_ARG(dest), MAC_PR_ARG(src),
+		  __entry->proto,
 		  BOOL_TO_STR(__entry->unencrypted))
 );
 
@@ -2835,6 +2839,7 @@ TRACE_EVENT(cfg80211_rx_control_port,
 	TP_STRUCT__entry(
 		NETDEV_ENTRY
 		__field(int, len)
+		MAC_ENTRY(to)
 		MAC_ENTRY(from)
 		__field(u16, proto)
 		__field(bool, unencrypted)
@@ -2842,12 +2847,14 @@ TRACE_EVENT(cfg80211_rx_control_port,
 	TP_fast_assign(
 		NETDEV_ASSIGN;
 		__entry->len = skb->len;
+		MAC_ASSIGN(to, eth_hdr(skb)->h_dest);
 		MAC_ASSIGN(from, eth_hdr(skb)->h_source);
 		__entry->proto = be16_to_cpu(skb->protocol);
 		__entry->unencrypted = unencrypted;
 	),
-	TP_printk(NETDEV_PR_FMT ", len=%d, " MAC_PR_FMT ", proto: 0x%x, unencrypted: %s",
-		  NETDEV_PR_ARG, __entry->len, MAC_PR_ARG(from),
+	TP_printk(NETDEV_PR_FMT ", len=%d, dest: " MAC_PR_FMT
+		  ", src: " MAC_PR_FMT ", proto: 0x%x, unencrypted: %s",
+		  NETDEV_PR_ARG, __entry->len, MAC_PR_ARG(to), MAC_PR_ARG(from),
 		  __entry->proto, BOOL_TO_STR(__entry->unencrypted))
 );