Re: [PATCH 09/11 net-next v5] bpf: remove ipv6_bpf_stub completely and use direct function calls
From: Martin KaFai Lau
Date: Wed Mar 25 2026 - 15:16:37 EST
On 3/25/26 5:08 AM, Fernando Fernandez Mancera wrote:
As IPv6 is built-in only, the ipv6_bpf_stub can be removed completely.
Convert all ipv6_bpf_stub usage to direct function calls instead. The
fallback functions introduced previously will prevent linkage errors
when CONFIG_IPV6 is disabled.
Thanks for working on this.
@@ -6221,8 +6215,8 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
if (likely(nhc->nhc_gw_family != AF_INET6))
neigh = __ipv4_neigh_lookup_noref(dev,
(__force u32)params->ipv4_dst);
- else
- neigh = __ipv6_neigh_lookup_noref_stub(dev, params->ipv6_dst);
+ else if (IS_ENABLED(CONFIG_IPV6))
+ neigh = __ipv6_neigh_lookup_noref(dev, params->ipv6_dst);
Should it be ipv6_mod_enabled() instead of IS_ENABLED(CONFIG_IPV6)?
Is nd_tbl always initialized?
if (!neigh || !(READ_ONCE(neigh->nud_state) & NUD_VALID))
return BPF_FIB_LKUP_RET_NO_NEIGH;
@@ -6290,12 +6284,11 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
params->tbid = 0;
}
- tb = ipv6_stub->fib6_get_table(net, tbid);
+ tb = fib6_get_table(net, tbid);
if (unlikely(!tb))
return BPF_FIB_LKUP_RET_NOT_FWDED;
- err = ipv6_stub->fib6_table_lookup(net, tb, oif, &fl6, &res,
- strict);
+ err = fib6_table_lookup(net, tb, oif, &fl6, &res, strict);
A similar question here and other changes in the patch.
I think bpf_ipv6_fib_lookup() is fine because the earlier
"!idev" check should fail when ipv6 is disabled at boot time?
} else {
if (flags & BPF_FIB_LOOKUP_MARK)
fl6.flowi6_mark = params->mark;
@@ -6305,7 +6298,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
fl6.flowi6_tun_key.tun_id = 0;
fl6.flowi6_uid = sock_net_uid(net, NULL);
- err = ipv6_stub->fib6_lookup(net, oif, &fl6, &res, strict);
+ err = fib6_lookup(net, oif, &fl6, &res, strict);
}
if (unlikely(err || IS_ERR_OR_NULL(res.f6i) ||
@@ -6326,11 +6319,11 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
return BPF_FIB_LKUP_RET_NOT_FWDED;
}
- ipv6_stub->fib6_select_path(net, &res, &fl6, fl6.flowi6_oif,
- fl6.flowi6_oif != 0, NULL, strict);
+ fib6_select_path(net, &res, &fl6, fl6.flowi6_oif,
+ fl6.flowi6_oif != 0, NULL, strict);
if (check_mtu) {
- mtu = ipv6_stub->ip6_mtu_from_fib6(&res, dst, src);
+ mtu = ip6_mtu_from_fib6(&res, dst, src);
if (params->tot_len > mtu) {
params->mtu_result = mtu; /* union with tot_len */
return BPF_FIB_LKUP_RET_FRAG_NEEDED;
@@ -6351,9 +6344,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
if (res.f6i->fib6_prefsrc.plen) {
*src = res.f6i->fib6_prefsrc.addr;
} else {
- err = ipv6_bpf_stub->ipv6_dev_get_saddr(net, dev,
- &fl6.daddr, 0,
- src);
+ err = ipv6_dev_get_saddr(net, dev, &fl6.daddr, 0, src);
if (err)
return BPF_FIB_LKUP_RET_NO_SRC_ADDR;
}
@@ -6365,7 +6356,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
/* xdp and cls_bpf programs are run in RCU-bh so rcu_read_lock_bh is
* not needed here.
*/
- neigh = __ipv6_neigh_lookup_noref_stub(dev, dst);
+ neigh = __ipv6_neigh_lookup_noref(dev, dst);
if (!neigh || !(READ_ONCE(neigh->nud_state) & NUD_VALID))
return BPF_FIB_LKUP_RET_NO_NEIGH;
memcpy(params->dmac, neigh->ha, ETH_ALEN);
@@ -6900,11 +6891,10 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
src6, tuple->ipv6.sport,
dst6, ntohs(tuple->ipv6.dport),
dif, sdif, &refcounted);
- else if (likely(ipv6_bpf_stub))
- sk = ipv6_bpf_stub->udp6_lib_lookup(net,
- src6, tuple->ipv6.sport,
- dst6, tuple->ipv6.dport,
- dif, sdif, NULL);
+ else if (likely(ipv6_mod_enabled()))
+ sk = __udp6_lib_lookup(net, src6, tuple->ipv6.sport,
+ dst6, tuple->ipv6.dport,
+ dif, sdif, NULL);
#endif
}
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index 9f40be0c3e71..f71ef82a5f3d 100644
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -13,7 +13,6 @@
#include <net/gre.h>
#include <net/ip.h>
#include <net/ip6_route.h>
-#include <net/ipv6_stubs.h>
struct bpf_lwt_prog {
struct bpf_prog *prog;
@@ -103,7 +102,12 @@ static int bpf_lwt_input_reroute(struct sk_buff *skb)
dev_put(dev);
} else if (skb->protocol == htons(ETH_P_IPV6)) {
skb_dst_drop(skb);
- err = ipv6_stub->ipv6_route_input(skb);
+ if (IS_ENABLED(CONFIG_IPV6)) {
+ ip6_route_input(skb);
+ err = skb_dst(skb)->error;
+ } else {
+ err = -EAFNOSUPPORT;
+ }
} else {
err = -EAFNOSUPPORT;
}
@@ -233,7 +237,7 @@ static int bpf_lwt_xmit_reroute(struct sk_buff *skb)
fl6.daddr = iph6->daddr;
fl6.saddr = iph6->saddr;
- dst = ipv6_stub->ipv6_dst_lookup_flow(net, skb->sk, &fl6, NULL);
+ dst = ip6_dst_lookup_flow(net, skb->sk, &fl6, NULL);
if (IS_ERR(dst)) {
err = PTR_ERR(dst);
goto err;
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index bb29b29fdcfb..07ae6ea7743a 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -264,8 +264,8 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
goto out;
}
-static int __inet6_bind(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len,
- u32 flags)
+int __inet6_bind(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len,
+ u32 flags)
{
struct sockaddr_in6 *addr = (struct sockaddr_in6 *)uaddr;
struct inet_sock *inet = inet_sk(sk);
@@ -1032,14 +1032,6 @@ static const struct ipv6_stub ipv6_stub_impl = {
.ip6_xmit = ip6_xmit,
};
-static const struct ipv6_bpf_stub ipv6_bpf_stub_impl = {
- .inet6_bind = __inet6_bind,
- .udp6_lib_lookup = __udp6_lib_lookup,
- .ipv6_setsockopt = do_ipv6_setsockopt,
- .ipv6_getsockopt = do_ipv6_getsockopt,
- .ipv6_dev_get_saddr = ipv6_dev_get_saddr,
-};
-
static int __init inet6_init(void)
{
struct list_head *r;
@@ -1199,7 +1191,6 @@ static int __init inet6_init(void)
/* ensure that ipv6 stubs are visible only after ipv6 is ready */
wmb();
ipv6_stub = &ipv6_stub_impl;
- ipv6_bpf_stub = &ipv6_bpf_stub_impl;
out:
return err;