[PATCH nf] netfilter: flowtable: restore wireless forward path

[Pablo Neira Ayuso <pablo@netfilter.org>]

Before commit 871df5007eda ("netfilter: flowtable: bail out if forward
path cannot be discovered"), there was a fallback to set up a forward
path in case .ndo_fill_forward_path fails or DEV_PATH_MTK_WDMA was used.
Such fallback was used by commit d787a3e38f01 ("mac80211: add support
for .ndo_fill_forward_path").

One possibility is to handle DEV_PATH_MTK_WDMA from the flowtable
forward path discovery. However, this is only used internally by drivers
to retrieve mtk_wdma information to set up hardware offload. Felix
decided to use the .fill_forward_path interface for this purpose due to
the lack of a better interface at that time.

Add a new DEV_PATH_IEEE80211 path which is offered if the new ieee80211
flag is set on in the struct net_device_path_ctx to restore the
flowtable with a ieee80211 netdevice. Handle this new DEV_PATH_IEEE80211
path just like DEV_PATH_ETHERNET and DEV_PATH_DSA, ie. this is the last
netdevice in the stack.

This new flag ieee80211 flag is implicitly unset for mtk_ppe and airoha
which call dev_fill_forward_path() to retrieve a DEV_PATH_MTK_WDMA path.

Fixes: 871df5007eda ("netfilter: flowtable: bail out if forward path cannot be discovered")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
supersedes
[nf,v2] net: update dev_fill_forward_path() to handle mac80211 special case

 include/linux/netdevice.h          | 3 +++
 net/mac80211/iface.c               | 7 +++++++
 net/netfilter/nf_flow_table_path.c | 3 +++
 3 files changed, 13 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 87cafc932e9e..3cff2174dc03 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -887,6 +887,7 @@ enum net_device_path_type {
 	DEV_PATH_DSA,
 	DEV_PATH_MTK_WDMA,
 	DEV_PATH_TUN,
+	DEV_PATH_IEEE80211,
 };
 
 struct net_device_path {
@@ -953,6 +954,8 @@ struct net_device_path_ctx {
 		u16		id;
 		__be16		proto;
 	} vlan[NET_DEVICE_PATH_VLAN_MAX];
+
+	bool			ieee80211;
 };
 
 enum tc_setup_type {
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 889c32fd8de1..68014ed99160 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1023,6 +1023,13 @@ static int ieee80211_netdev_fill_forward_path(struct net_device_path_ctx *ctx,
 	struct sta_info *sta;
 	int ret = -ENOENT;
 
+	if (path->ieee80211) {
+		path->type = DEV_PATH_IEEE80211;
+		path->dev = ctx->dev;
+		ctx->dev = NULL;
+		return 0;
+	}
+
 	sdata = IEEE80211_DEV_TO_SUB_IF(ctx->dev);
 	local = sdata->local;
 
diff --git a/net/netfilter/nf_flow_table_path.c b/net/netfilter/nf_flow_table_path.c
index 1e55644f2edb..d90013685bf1 100644
--- a/net/netfilter/nf_flow_table_path.c
+++ b/net/netfilter/nf_flow_table_path.c
@@ -53,6 +53,7 @@ static int nft_dev_fill_forward_path(const struct dst_entry *dst_cache,
 	struct net_device_path_ctx ctx = {
 		.dev = dev,
 		.ether_type = ether_type,
+		.ieee80211 = true,
 	};
 	struct neighbour *n;
 	u8 nud_state;
@@ -114,6 +115,7 @@ static int nft_dev_path_info(struct net_device_path_stack *stack,
 		path = &stack->path[i];
 		switch (path->type) {
 		case DEV_PATH_ETHERNET:
+		case DEV_PATH_IEEE80211:
 		case DEV_PATH_DSA:
 		case DEV_PATH_VLAN:
 		case DEV_PATH_PPPOE:
@@ -123,6 +125,7 @@ static int nft_dev_path_info(struct net_device_path_stack *stack,
 				memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
 
 			if (path->type == DEV_PATH_ETHERNET ||
+			    path->type == DEV_PATH_IEEE80211 ||
 			    path->type == DEV_PATH_DSA)
 				break;
 
-- 
2.47.3