From 1d47b55b36d2ec73fe6901212c8b28a593c3b27c Mon Sep 17 00:00:00 2001 From: Weiming Shi Date: Mon, 27 Apr 2026 14:34:50 +0200 Subject: netfilter: nft_fwd_netdev: use recursion counter in neigh egress path nft_fwd_neigh can be used in egress chains (NF_NETDEV_EGRESS). When the forwarding rule targets the same device or two devices forward to each other, neigh_xmit() triggers dev_queue_xmit() which re-enters nf_hook_egress(), causing infinite recursion and stack overflow. Move the nf_get_nf_dup_skb_recursion() accessor and NF_RECURSION_LIMIT to the shared header nf_dup_netdev.h as a static inline, so that nft_fwd_netdev can use the recursion counter directly without exported function call overhead. Guard neigh_xmit() with the same recursion limit already used in nf_do_netdev_egress(). [ Updated to cache the nf_get_nf_dup_skb_recursion pointer. --pablo ] Fixes: f87b9464d152 ("netfilter: nft_fwd_netdev: Support egress hook") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_dup_netdev.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/net') diff --git a/include/net/netfilter/nf_dup_netdev.h b/include/net/netfilter/nf_dup_netdev.h index b175d271aec9..609bcf422a9b 100644 --- a/include/net/netfilter/nf_dup_netdev.h +++ b/include/net/netfilter/nf_dup_netdev.h @@ -3,10 +3,23 @@ #define _NF_DUP_NETDEV_H_ #include +#include +#include void nf_dup_netdev_egress(const struct nft_pktinfo *pkt, int oif); void nf_fwd_netdev_egress(const struct nft_pktinfo *pkt, int oif); +#define NF_RECURSION_LIMIT 2 + +static inline u8 *nf_get_nf_dup_skb_recursion(void) +{ +#ifndef CONFIG_PREEMPT_RT + return this_cpu_ptr(&softnet_data.xmit.nf_dup_skb_recursion); +#else + return ¤t->net_xmit.nf_dup_skb_recursion; +#endif +} + struct nft_offload_ctx; struct nft_flow_rule; -- cgit v1.2.3 From 69c54f80f4a7072b51b5b5939185ca5e572be982 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 30 Apr 2026 16:49:53 +0200 Subject: netfilter: flowtable: fix inline pppoe encapsulation in xmit path Address two issues in the inline pppoe encapsulation: - Add needs_gso_segment flag to segment PPPoE packets in software given that there is no GSO support for this. - Use FLOW_OFFLOAD_XMIT_DIRECT since neighbour cache is not available in point-to-point device, use the hardware address that is obtained via flowtable path discovery (ie. fill_forward_path). Fixes: 18d27bed0880 ("netfilter: flowtable: inline pppoe encapsulation in xmit path") Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_flow_table.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/net') diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h index b09c11c048d5..7b23b245a5a8 100644 --- a/include/net/netfilter/nf_flow_table.h +++ b/include/net/netfilter/nf_flow_table.h @@ -148,9 +148,10 @@ struct flow_offload_tuple { /* All members above are keys for lookups, see flow_offload_hash(). */ struct { } __hash; - u8 dir:2, + u16 dir:2, xmit_type:3, encap_num:2, + needs_gso_segment:1, tun_num:2, in_vlan_ingress:2; u16 mtu; @@ -232,6 +233,7 @@ struct nf_flow_route { u32 hw_ifindex; u8 h_source[ETH_ALEN]; u8 h_dest[ETH_ALEN]; + u8 needs_gso_segment:1; } out; enum flow_offload_xmit_type xmit_type; } tuple[FLOW_OFFLOAD_DIR_MAX]; -- cgit v1.2.3