Re: [PATCH 09/11 net-next v5] bpf: remove ipv6_bpf_stub completely and use direct function calls
From: Martin KaFai Lau <martin.lau@linux.dev>
Date: 2026-03-25 19:11:53
Also in:
bpf, lkml
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.
quoted hunk ↗ jump to hunk
@@ -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?
quoted hunk ↗ jump to hunk
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?
quoted hunk ↗ jump to hunk
} 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;