indirect calls are only needed if ipv6 is a module.
Add helpers to abstract the v6ops indirections and use them instead.

reroute is kept as indirect call here; its only used with nfqueue and only
when userspace modified packet or metadata (nfmark).

v2:
 - fix build failure with CONFIG_NETFILTER=n
 - fix build failure with CONFIG_IPV6=n

Signed-off-by: Florian Westphal <[email protected]>
---
 include/linux/netfilter_ipv6.h    | 87 +++++++++++++++++++++++++++----
 net/bridge/br_netfilter_hooks.c   |  7 +--
 net/bridge/br_netfilter_ipv6.c    | 22 ++++++--
 net/ipv6/netfilter.c              | 13 ++---
 net/ipv6/netfilter/nft_fib_ipv6.c |  9 +---
 net/netfilter/utils.c             |  6 +--
 net/netfilter/xt_addrtype.c       | 16 ++----
 net/openvswitch/actions.c         |  6 +--
 8 files changed, 113 insertions(+), 53 deletions(-)

diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index ad4223c10488..ab446bee56a2 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -9,6 +9,10 @@
 
 #include <uapi/linux/netfilter_ipv6.h>
 
+/* IPV6=y -- need prototypes for direct calls */
+#include <net/addrconf.h>
+#include <net/ip6_route.h>
+
 /* Extra routing may needed on local out, as the QUEUE target never returns
  * control to the table.
  */
@@ -25,29 +29,24 @@ struct nf_queue_entry;
  * if IPv6 is a module.
  */
 struct nf_ipv6_ops {
+#if IS_MODULE(CONFIG_IPV6)
        int (*chk_addr)(struct net *net, const struct in6_addr *addr,
                        const struct net_device *dev, int strict);
        void (*route_input)(struct sk_buff *skb);
        int (*fragment)(struct net *net, struct sock *sk, struct sk_buff *skb,
                        int (*output)(struct net *, struct sock *, struct 
sk_buff *));
-       int (*route)(struct net *net, struct dst_entry **dst, struct flowi *fl,
-                    bool strict);
-       int (*reroute)(struct sk_buff *skb, const struct nf_queue_entry *entry);
-#if IS_MODULE(CONFIG_IPV6)
        int (*route_me_harder)(struct net *net, struct sk_buff *skb);
        int (*dev_get_saddr)(struct net *net, const struct net_device *dev,
                       const struct in6_addr *daddr, unsigned int srcprefs,
                       struct in6_addr *saddr);
+       int (*route)(struct net *net, struct dst_entry **dst, struct flowi *fl,
+                    bool strict);
 #endif
+       int (*reroute)(struct sk_buff *skb, const struct nf_queue_entry *entry);
 };
 
 #ifdef CONFIG_NETFILTER
-int ip6_route_me_harder(struct net *net, struct sk_buff *skb);
-__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
-                       unsigned int dataoff, u_int8_t protocol);
-
-int ipv6_netfilter_init(void);
-void ipv6_netfilter_fini(void);
+#include <net/addrconf.h>
 
 extern const struct nf_ipv6_ops __rcu *nf_ipv6_ops;
 static inline const struct nf_ipv6_ops *nf_get_ipv6_ops(void)
@@ -55,10 +54,78 @@ static inline const struct nf_ipv6_ops 
*nf_get_ipv6_ops(void)
        return rcu_dereference(nf_ipv6_ops);
 }
 
+static inline int nf_ipv6_chk_addr(struct net *net, const struct in6_addr 
*addr,
+                                  const struct net_device *dev, int strict)
+{
+#if IS_MODULE(CONFIG_IPV6)
+       const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops();
+
+       if (!v6_ops)
+               return 1;
+
+       return v6_ops->chk_addr(net, addr, dev, strict);
+#else
+       return ipv6_chk_addr(net, addr, dev, strict);
+#endif
+}
+
+static inline int
+nf_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+               int (*output)(struct net *, struct sock *, struct sk_buff *))
+{
+#if IS_MODULE(CONFIG_IPV6)
+       const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
+
+       if (v6ops)
+               return v6ops->fragment(net, sk, skb, output);
+#endif
+#if IS_BUILTIN(CONFIG_IPV6)
+       return ip6_fragment(net, sk, skb, output);
+#endif
+       kfree_skb(skb);
+       return -EMSGSIZE;
+}
+
+int __nf_ip6_route(struct net *net, struct dst_entry **dst,
+                              struct flowi *fl, bool strict);
+
+static inline int nf_ip6_route(struct net *net, struct dst_entry **dst,
+                              struct flowi *fl, bool strict)
+{
+#if IS_MODULE(CONFIG_IPV6)
+       const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
+
+       if (v6ops)
+               return v6ops->route(net, dst, fl, strict);
+
+       return -EHOSTUNREACH;
+#endif
+#if IS_BUILTIN(CONFIG_IPV6)
+       return __nf_ip6_route(net, dst, fl, strict);
+#else
+       return -EHOSTUNREACH;
+#endif
+}
+
+int ip6_route_me_harder(struct net *net, struct sk_buff *skb);
+__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
+                       unsigned int dataoff, u_int8_t protocol);
+
+int ipv6_netfilter_init(void);
+void ipv6_netfilter_fini(void);
+
 #else /* CONFIG_NETFILTER */
 static inline int ipv6_netfilter_init(void) { return 0; }
 static inline void ipv6_netfilter_fini(void) { return; }
 static inline const struct nf_ipv6_ops *nf_get_ipv6_ops(void) { return NULL; }
+
+static inline int
+nf_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+               int (*output)(struct net *, struct sock *, struct sk_buff *))
+{
+       kfree_skb(skb);
+       return -EMSGSIZE;
+}
 #endif /* CONFIG_NETFILTER */
 
 #endif /*__LINUX_IP6_NETFILTER_H*/
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 40d058378b52..9e7686bef5b9 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -744,7 +744,6 @@ static int br_nf_dev_queue_xmit(struct net *net, struct 
sock *sk, struct sk_buff
        }
        if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
            skb->protocol == htons(ETH_P_IPV6)) {
-               const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
                struct brnf_frag_data *data;
 
                if (br_validate_ipv6(net, skb))
@@ -761,11 +760,7 @@ static int br_nf_dev_queue_xmit(struct net *net, struct 
sock *sk, struct sk_buff
                skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
                                                 data->size);
 
-               if (v6ops)
-                       return v6ops->fragment(net, sk, skb, 
br_nf_push_frag_xmit);
-
-               kfree_skb(skb);
-               return -EMSGSIZE;
+               return nf_ip6_fragment(net, sk, skb, br_nf_push_frag_xmit);
        }
        nf_bridge_info_free(skb);
        return br_dev_queue_push_xmit(net, sk, skb);
diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
index 94039f588f1d..424c77817aff 100644
--- a/net/bridge/br_netfilter_ipv6.c
+++ b/net/bridge/br_netfilter_ipv6.c
@@ -35,7 +35,7 @@
 #include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/addrconf.h>
-#include <net/route.h>
+#include <net/ip6_route.h>
 #include <net/netfilter/br_netfilter.h>
 
 #include <linux/uaccess.h>
@@ -155,6 +155,22 @@ br_nf_ipv6_daddr_was_changed(const struct sk_buff *skb,
                      sizeof(ipv6_hdr(skb)->daddr)) != 0;
 }
 
+static bool br_nf_ip6_route_input(struct sk_buff *skb)
+{
+#if IS_MODULE(CONFIG_IPV6)
+       const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
+
+       if (!v6ops)
+               return false;
+
+       v6ops->route_input(skb);
+#else
+       ip6_route_input(skb);
+#endif
+
+       return skb_dst(skb)->error ? false : true;
+}
+
 /* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables
  * PREROUTING and continue the bridge PRE_ROUTING hook. See comment
  * for br_nf_pre_routing_finish(), same logic is used here but
@@ -165,7 +181,6 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, 
struct sock *sk, struc
        struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
        struct rtable *rt;
        struct net_device *dev = skb->dev;
-       const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 
        nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 
@@ -176,9 +191,8 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, 
struct sock *sk, struc
        nf_bridge->in_prerouting = 0;
        if (br_nf_ipv6_daddr_was_changed(skb, nf_bridge)) {
                skb_dst_drop(skb);
-               v6ops->route_input(skb);
 
-               if (skb_dst(skb)->error) {
+               if (!br_nf_ip6_route_input(skb)) {
                        kfree_skb(skb);
                        return 0;
                }
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 0a5caf263889..8de3574e1377 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -84,8 +84,8 @@ static int nf_ip6_reroute(struct sk_buff *skb,
        return 0;
 }
 
-static int nf_ip6_route(struct net *net, struct dst_entry **dst,
-                       struct flowi *fl, bool strict)
+int __nf_ip6_route(struct net *net, struct dst_entry **dst,
+                  struct flowi *fl, bool strict)
 {
        static const struct ipv6_pinfo fake_pinfo;
        static const struct inet_sock fake_sk = {
@@ -105,17 +105,18 @@ static int nf_ip6_route(struct net *net, struct dst_entry 
**dst,
                *dst = result;
        return err;
 }
+EXPORT_SYMBOL_GPL(__nf_ip6_route);
 
 static const struct nf_ipv6_ops ipv6ops = {
+#if IS_MODULE(CONFIG_IPV6)
        .chk_addr               = ipv6_chk_addr,
-       .route_input            = ip6_route_input,
+       .route_input            = ip6_route_input,
        .fragment               = ip6_fragment,
-       .route                  = nf_ip6_route,
-       .reroute                = nf_ip6_reroute,
-#if IS_MODULE(CONFIG_IPV6)
        .route_me_harder        = ip6_route_me_harder,
        .dev_get_saddr          = ipv6_dev_get_saddr,
+       .route                  = __nf_ip6_route,
 #endif
+       .reroute                = nf_ip6_reroute,
 };
 
 int __init ipv6_netfilter_init(void)
diff --git a/net/ipv6/netfilter/nft_fib_ipv6.c 
b/net/ipv6/netfilter/nft_fib_ipv6.c
index 36be3cf0adef..73cdc0bc63f7 100644
--- a/net/ipv6/netfilter/nft_fib_ipv6.c
+++ b/net/ipv6/netfilter/nft_fib_ipv6.c
@@ -59,7 +59,6 @@ static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
                                struct ipv6hdr *iph)
 {
        const struct net_device *dev = NULL;
-       const struct nf_ipv6_ops *v6ops;
        int route_err, addrtype;
        struct rt6_info *rt;
        struct flowi6 fl6 = {
@@ -68,10 +67,6 @@ static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
        };
        u32 ret = 0;
 
-       v6ops = nf_get_ipv6_ops();
-       if (!v6ops)
-               return RTN_UNREACHABLE;
-
        if (priv->flags & NFTA_FIB_F_IIF)
                dev = nft_in(pkt);
        else if (priv->flags & NFTA_FIB_F_OIF)
@@ -79,10 +74,10 @@ static u32 __nft_fib6_eval_type(const struct nft_fib *priv,
 
        nft_fib6_flowi_init(&fl6, priv, pkt, dev, iph);
 
-       if (dev && v6ops->chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
+       if (dev && nf_ipv6_chk_addr(nft_net(pkt), &fl6.daddr, dev, true))
                ret = RTN_LOCAL;
 
-       route_err = v6ops->route(nft_net(pkt), (struct dst_entry **)&rt,
+       route_err = nf_ip6_route(nft_net(pkt), (struct dst_entry **)&rt,
                                 flowi6_to_flowi(&fl6), false);
        if (route_err)
                goto err;
diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
index 55af9f247993..06dc55590441 100644
--- a/net/netfilter/utils.c
+++ b/net/netfilter/utils.c
@@ -162,7 +162,7 @@ EXPORT_SYMBOL_GPL(nf_checksum_partial);
 int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
             bool strict, unsigned short family)
 {
-       const struct nf_ipv6_ops *v6ops;
+       const struct nf_ipv6_ops *v6ops __maybe_unused;
        int ret = 0;
 
        switch (family) {
@@ -170,9 +170,7 @@ int nf_route(struct net *net, struct dst_entry **dst, 
struct flowi *fl,
                ret = nf_ip_route(net, dst, fl, strict);
                break;
        case AF_INET6:
-               v6ops = rcu_dereference(nf_ipv6_ops);
-               if (v6ops)
-                       ret = v6ops->route(net, dst, fl, strict);
+               ret = nf_ip6_route(net, dst, fl, strict);
                break;
        }
 
diff --git a/net/netfilter/xt_addrtype.c b/net/netfilter/xt_addrtype.c
index 89e281b3bfc2..29987ff03621 100644
--- a/net/netfilter/xt_addrtype.c
+++ b/net/netfilter/xt_addrtype.c
@@ -36,7 +36,6 @@ MODULE_ALIAS("ip6t_addrtype");
 static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
                            const struct in6_addr *addr, u16 mask)
 {
-       const struct nf_ipv6_ops *v6ops;
        struct flowi6 flow;
        struct rt6_info *rt;
        u32 ret = 0;
@@ -47,18 +46,13 @@ static u32 match_lookup_rt6(struct net *net, const struct 
net_device *dev,
        if (dev)
                flow.flowi6_oif = dev->ifindex;
 
-       v6ops = nf_get_ipv6_ops();
-       if (v6ops) {
-               if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
-                       if (v6ops->chk_addr(net, addr, dev, true))
-                               ret = XT_ADDRTYPE_LOCAL;
-               }
-               route_err = v6ops->route(net, (struct dst_entry **)&rt,
-                                        flowi6_to_flowi(&flow), false);
-       } else {
-               route_err = 1;
+       if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
+               if (nf_ipv6_chk_addr(net, addr, dev, true))
+                       ret = XT_ADDRTYPE_LOCAL;
        }
 
+       route_err = nf_ip6_route(net, (struct dst_entry **)&rt,
+                                flowi6_to_flowi(&flow), false);
        if (route_err)
                return XT_ADDRTYPE_UNREACHABLE;
 
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index e47ebbbe71b8..a1437c12bf6b 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -915,13 +915,9 @@ static void ovs_fragment(struct net *net, struct vport 
*vport,
                ip_do_fragment(net, skb->sk, skb, ovs_vport_output);
                refdst_drop(orig_dst);
        } else if (key->eth.type == htons(ETH_P_IPV6)) {
-               const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
                unsigned long orig_dst;
                struct rt6_info ovs_rt;
 
-               if (!v6ops)
-                       goto err;
-
                prepare_frag(vport, skb, orig_network_offset,
                             ovs_key_mac_proto(key));
                memset(&ovs_rt, 0, sizeof(ovs_rt));
@@ -933,7 +929,7 @@ static void ovs_fragment(struct net *net, struct vport 
*vport,
                skb_dst_set_noref(skb, &ovs_rt.dst);
                IP6CB(skb)->frag_max_size = mru;
 
-               v6ops->fragment(net, skb->sk, skb, ovs_vport_output);
+               nf_ip6_fragment(net, skb->sk, skb, ovs_vport_output);
                refdst_drop(orig_dst);
        } else {
                WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
-- 
2.19.2

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