[PATCH bpf-next v2 2/4] net: move netfilter nf_reject6_fill_skb_dst to core ipv6

Mahe Tardy
2025-07-25T18:55:51Z

Move and rename nf_reject6_fill_skb_dst from
ipv6/netfilter/nf_reject_ipv6 to ip6_route_reply_fetch_dst in
ipv6/route.c so that it can be reused in the following patches by BPF
kfuncs.

Netfilter uses nf_ip6_route that is almost a transparent wrapper around
ip6_route_outputy so this patch inlines it.

Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>
---
include/net/ip6_route.h | 2 ++
net/ipv6/netfilter/nf_reject_ipv6.c | 17 +----------------
net/ipv6/route.c | 18 ++++++++++++++++++
3 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 6dbdf60b342f..1426467df547 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -93,6 +93,8 @@ static inline struct dst_entry *ip6_route_output(struct net *net,
return ip6_route_output_flags(net, sk, fl6, 0);
}

+int ip6_route_reply_fetch_dst(struct sk_buff *skb);
+
/* Only conditionally release dst if flags indicates
* !RT6_LOOKUP_F_DST_NOREF or dst is in uncached_list.
*/
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index 9ae2b2725bf9..994a3b88ac52 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -250,21 +250,6 @@ void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb,
}
EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put);

-static int nf_reject6_fill_skb_dst(struct sk_buff *skb_in)
-{
- struct dst_entry *dst = NULL;
- struct flowi fl;
-
- memset(&fl, 0, sizeof(struct flowi));
- fl.u.ip6.daddr = ipv6_hdr(skb_in)->saddr;
- nf_ip6_route(dev_net(skb_in->dev), &dst, &fl, false);
- if (!dst)
- return -1;
-
- skb_dst_set(skb_in, dst);
- return 0;
-}
-
void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
int hook)
{
@@ -398,7 +383,7 @@ void nf_send_unreach6(struct net *net, struct sk_buff *skb_in,
skb_in->dev = net->loopback_dev;

if ((hooknum == NF_INET_PRE_ROUTING || hooknum == NF_INET_INGRESS) &&
- nf_reject6_fill_skb_dst(skb_in) < 0)
+ ip6_route_reply_fetch_dst(skb_in) < 0)
return;

icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 0d5464c64965..de61540f9524 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2705,6 +2705,24 @@ struct dst_entry *ip6_route_output_flags(struct net *net,
}
EXPORT_SYMBOL_GPL(ip6_route_output_flags);

+int ip6_route_reply_fetch_dst(struct sk_buff *skb)
+{
+ struct dst_entry *result;
+ struct flowi6 fl = {
+ .daddr = ipv6_hdr(skb)->saddr
+ };
+ int err;
+
+ result = ip6_route_output(dev_net(skb->dev), NULL, &fl);
+ err = result->error;
+ if (err)
+ dst_release(result);
+ else
+ skb_dst_set(skb, result);
+ return err;
+}
+EXPORT_SYMBOL_GPL(ip6_route_reply_fetch_dst);
+
struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{
struct rt6_info *rt, *ort = dst_rt6_info(dst_orig);
--
2.34.1