[PATCH net-next v2 3/7] netfilter: Switch to skb_dstref_steal to clear dst_entry
From: Stanislav Fomichev <sdf@fomichev.me>
Date: 2025-08-18 15:40:37
Also in:
linux-staging, lkml, netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Going forward skb_dst_set will assert that skb dst_entry is empty during skb_dst_set. skb_dstref_steal is added to reset existing entry without doing refcnt. Switch to skb_dstref_steal in ip[6]_route_me_harder and add a comment on why it's safe to skip skb_dstref_restore. Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me> --- net/ipv4/netfilter.c | 5 ++++- net/ipv6/netfilter.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index 0565f001120d..e60e54e7945d 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c@@ -65,7 +65,10 @@ int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, un if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && xfrm_decode_session(net, skb, flowi4_to_flowi(&fl4), AF_INET) == 0) { struct dst_entry *dst = skb_dst(skb); - skb_dst_set(skb, NULL); + /* ignore return value from skb_dstref_steal, xfrm_lookup takes + * care of dropping the refcnt if needed. + */ + skb_dstref_steal(skb); dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0); if (IS_ERR(dst)) return PTR_ERR(dst);
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 45f9105f9ac1..46540a5a4331 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c@@ -63,7 +63,10 @@ int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff #ifdef CONFIG_XFRM if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && xfrm_decode_session(net, skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { - skb_dst_set(skb, NULL); + /* ignore return value from skb_dstref_steal, xfrm_lookup takes + * care of dropping the refcnt if needed. + */ + skb_dstref_steal(skb); dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); if (IS_ERR(dst)) return PTR_ERR(dst);
--
2.50.1