Re: [PATCH bpf-next v8 1/7] net: move netfilter nf_reject_fill_skb_dst to core ipv4
From: "Emil Tsalapatis" <emil@etsalapatis.com>
Date: 2026-06-24 00:09:58
Also in:
bpf, netfilter-devel
On Mon Jun 22, 2026 at 8:05 AM EDT, Mahe Tardy wrote:
Move and rename nf_reject_fill_skb_dst from ipv4/netfilter/nf_reject_ipv4 to ip_route_reply_fill_dst in ipv4/route.c so that it can be reused in the following patches by BPF kfuncs. Netfilter uses nf_ip_route that is almost a transparent wrapper around ip_route_output_key so this patch inlines it. Reviewed-by: Jordan Rife <redacted> Signed-off-by: Mahe Tardy <redacted>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
quoted hunk ↗ jump to hunk
--- include/net/route.h | 1 + net/ipv4/netfilter/nf_reject_ipv4.c | 19 ++----------------- net/ipv4/route.c | 15 +++++++++++++++ 3 files changed, 18 insertions(+), 17 deletions(-)diff --git a/include/net/route.h b/include/net/route.h index f90106f383c5..300d292cd9a1 100644 --- a/include/net/route.h +++ b/include/net/route.h@@ -173,6 +173,7 @@ struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp, const struct sock *sk); struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig); +int ip_route_reply_fill_dst(struct sk_buff *skb); static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp) {diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index fecf6621f679..c1c0724e4d4d 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c@@ -252,21 +252,6 @@ static void nf_reject_ip_tcphdr_put(struct sk_buff *nskb, const struct sk_buff * nskb->csum_offset = offsetof(struct tcphdr, check); } -static int nf_reject_fill_skb_dst(struct sk_buff *skb_in) -{ - struct dst_entry *dst = NULL; - struct flowi fl; - - memset(&fl, 0, sizeof(struct flowi)); - fl.u.ip4.daddr = ip_hdr(skb_in)->saddr; - nf_ip_route(dev_net(skb_in->dev), &dst, &fl, false); - if (!dst) - return -1; - - skb_dst_set(skb_in, dst); - return 0; -} - /* Send RST reply */ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, int hook)@@ -279,7 +264,7 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, if (!oth) return; - if (!skb_dst(oldskb) && nf_reject_fill_skb_dst(oldskb) < 0) + if (!skb_dst(oldskb) && ip_route_reply_fill_dst(oldskb) < 0) return; if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))@@ -352,7 +337,7 @@ void nf_send_unreach(struct sk_buff *skb_in, int code, int hook) if (iph->frag_off & htons(IP_OFFSET)) return; - if (!skb_dst(skb_in) && nf_reject_fill_skb_dst(skb_in) < 0) + if (!skb_dst(skb_in) && ip_route_reply_fill_dst(skb_in) < 0) return; if (skb_csum_unnecessary(skb_in) ||diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 3f3de5164d6e..f24609933fbe 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c@@ -2942,6 +2942,21 @@ struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4, } EXPORT_SYMBOL_GPL(ip_route_output_flow); +int ip_route_reply_fill_dst(struct sk_buff *skb) +{ + struct rtable *rt; + struct flowi4 fl4 = { + .daddr = ip_hdr(skb)->saddr + }; + + rt = ip_route_output_key(dev_net(skb->dev), &fl4); + if (IS_ERR(rt)) + return PTR_ERR(rt); + skb_dst_set(skb, &rt->dst); + return 0; +} +EXPORT_SYMBOL_GPL(ip_route_reply_fill_dst); + /* called with rcu_read_lock held */ static int rt_fill_info(struct net *net, __be32 dst, __be32 src, struct rtable *rt, u32 table_id, dscp_t dscp, --2.34.1