net: add bool confirm_neigh parameter for dst_ops.update_pmtu

The MTU update code is supposed to be invoked in response to real
networking events that update the PMTU. In IPv6 PMTU update function
__ip6_rt_update_pmtu() we called dst_confirm_neigh() to update neighbor
confirmed time.

But for tunnel code, it will call pmtu before xmit, like:
  - tnl_update_pmtu()
    - skb_dst_update_pmtu()
      - ip6_rt_update_pmtu()
        - __ip6_rt_update_pmtu()
          - dst_confirm_neigh()

If the tunnel remote dst mac address changed and we still do the neigh
confirm, we will not be able to update neigh cache and ping6 remote
will failed.

So for this ip_tunnel_xmit() case, _EVEN_ if the MTU is changed, we
should not be invoking dst_confirm_neigh() as we have no evidence
of successful two-way communication at this point.

On the other hand it is also important to keep the neigh reachability fresh
for TCP flows, so we cannot remove this dst_confirm_neigh() call.

To fix the issue, we have to add a new bool parameter for dst_ops.update_pmtu
to choose whether we should do neigh update or not. I will add the parameter
in this patch and set all the callers to true to comply with the previous
way, and fix the tunnel code one by one on later patches.

v5: No change.
v4: No change.
v3: Do not remove dst_confirm_neigh, but add a new bool parameter in
    dst_ops.update_pmtu to control whether we should do neighbor confirm.
    Also split the big patch to small ones for each area.
v2: Remove dst_confirm_neigh in __ip6_rt_update_pmtu.

Suggested-by: David Miller <davem@davemloft.net>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index e5b7d6d2286e0c25b7bf2c4bf039f64ecd871122..913062017be97557a05384e9ecf64bec357241a0 100644 (file)
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -540,7 +540,7 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
                mtu = dst_mtu(&rt->dst);
        }
 
-       rt->dst.ops->update_pmtu(&rt->dst, NULL, skb, mtu);
+       rt->dst.ops->update_pmtu(&rt->dst, NULL, skb, mtu, true);
 
        if (!skb_is_gso(skb) && (iph->frag_off & htons(IP_DF)) &&
            mtu < ntohs(iph->tot_len)) {

diff --git a/include/net/dst.h b/include/net/dst.h
index 8224dad2ae9460fb3ef3ace54f4442e76463ac04..593630e0e0763df11fb4582db244435fa6bf629f 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -516,7 +516,7 @@ static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
        struct dst_entry *dst = skb_dst(skb);
 
        if (dst && dst->ops->update_pmtu)
-               dst->ops->update_pmtu(dst, NULL, skb, mtu);
+               dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
 }
 
 static inline void skb_tunnel_check_pmtu(struct sk_buff *skb,

diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h
index 5ec645f27ee3841f9a4074c94e5dca37bb86fc2e..443863c7b8da362476c15fd290ac2a32a8aa86e3 100644 (file)
--- a/include/net/dst_ops.h
+++ b/include/net/dst_ops.h
@@ -27,7 +27,8 @@ struct dst_ops {
        struct dst_entry *      (*negative_advice)(struct dst_entry *);
        void                    (*link_failure)(struct sk_buff *);
        void                    (*update_pmtu)(struct dst_entry *dst, struct sock *sk,
-                                              struct sk_buff *skb, u32 mtu);
+                                              struct sk_buff *skb, u32 mtu,
+                                              bool confirm_neigh);
        void                    (*redirect)(struct dst_entry *dst, struct sock *sk,
                                            struct sk_buff *skb);
        int                     (*local_out)(struct net *net, struct sock *sk, struct sk_buff *skb);

diff --git a/net/bridge/br_nf_core.c b/net/bridge/br_nf_core.c
index 2cdfc5d6c25db6d9b565d33833360a9ab0c578c2..8c69f0c95a8ed4d92b6991d05e2c0d8133c9425c 100644 (file)
--- a/net/bridge/br_nf_core.c
+++ b/net/bridge/br_nf_core.c
@@ -22,7 +22,8 @@
 #endif
 
 static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                            struct sk_buff *skb, u32 mtu)
+                            struct sk_buff *skb, u32 mtu,
+                            bool confirm_neigh)
 {
 }
 

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index aea918135ec370e3b12cea1ea14319c1ce5cb64b..08c3dc45f1a4344ca919b0fd1a6c73ec04247d05 100644 (file)
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -110,7 +110,8 @@ static void dn_dst_ifdown(struct dst_entry *, struct net_device *dev, int how);
 static struct dst_entry *dn_dst_negative_advice(struct dst_entry *);
 static void dn_dst_link_failure(struct sk_buff *);
 static void dn_dst_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                              struct sk_buff *skb , u32 mtu);
+                              struct sk_buff *skb , u32 mtu,
+                              bool confirm_neigh);
 static void dn_dst_redirect(struct dst_entry *dst, struct sock *sk,
                            struct sk_buff *skb);
 static struct neighbour *dn_dst_neigh_lookup(const struct dst_entry *dst,
@@ -251,7 +252,8 @@ static int dn_dst_gc(struct dst_ops *ops)
  * advertise to the other end).
  */
 static void dn_dst_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                              struct sk_buff *skb, u32 mtu)
+                              struct sk_buff *skb, u32 mtu,
+                              bool confirm_neigh)
 {
        struct dn_route *rt = (struct dn_route *) dst;
        struct neighbour *n = rt->n;

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index e4c6e8b4049063f5239a5e99a185016ad3bb5790..18c0d5bffe12b04b48faedc247bb3e491a7abcea 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1086,7 +1086,7 @@ struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
                if (!dst)
                        goto out;
        }
-       dst->ops->update_pmtu(dst, sk, NULL, mtu);
+       dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
 
        dst = __sk_dst_check(sk, 0);
        if (!dst)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f88c93c38f1173614363b10cab7362771dd9ed8c..87e979f2b74a5fd3b4f3b70250ffd6de4ef6212f 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -139,7 +139,8 @@ static unsigned int  ipv4_mtu(const struct dst_entry *dst);
 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
 static void             ipv4_link_failure(struct sk_buff *skb);
 static void             ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                                          struct sk_buff *skb, u32 mtu);
+                                          struct sk_buff *skb, u32 mtu,
+                                          bool confirm_neigh);
 static void             ip_do_redirect(struct dst_entry *dst, struct sock *sk,
                                        struct sk_buff *skb);
 static void            ipv4_dst_destroy(struct dst_entry *dst);
@@ -1043,7 +1044,8 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 }
 
 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                             struct sk_buff *skb, u32 mtu)
+                             struct sk_buff *skb, u32 mtu,
+                             bool confirm_neigh)
 {
        struct rtable *rt = (struct rtable *) dst;
        struct flowi4 fl4;
@@ -2687,7 +2689,8 @@ static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
 }
 
 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                                         struct sk_buff *skb, u32 mtu)
+                                         struct sk_buff *skb, u32 mtu,
+                                         bool confirm_neigh)
 {
 }
 

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 35b84b52b7027b35f65b36d6a0160913e8df2c5a..9ebd54752e03b81a01f6c53cc17cebbccd928137 100644 (file)
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -100,12 +100,13 @@ static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 }
 
 static void xfrm4_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                             struct sk_buff *skb, u32 mtu)
+                             struct sk_buff *skb, u32 mtu,
+                             bool confirm_neigh)
 {
        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
        struct dst_entry *path = xdst->route;
 
-       path->ops->update_pmtu(path, sk, skb, mtu);
+       path->ops->update_pmtu(path, sk, skb, mtu, confirm_neigh);
 }
 
 static void xfrm4_redirect(struct dst_entry *dst, struct sock *sk,

diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index fe9cb8d1adca069b39990307ac8ab1f7972e598a..e315526fa244ab83363495d4cfa0def7e3decf85 100644 (file)
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -146,7 +146,7 @@ struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
 
        if (IS_ERR(dst))
                return NULL;
-       dst->ops->update_pmtu(dst, sk, NULL, mtu);
+       dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
 
        dst = inet6_csk_route_socket(sk, &fl6);
        return IS_ERR(dst) ? NULL : dst;

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 9d0965252ddf723a0f4e64b8f4ef18675bdd55a3..3ba69174ad6c0539383817c5ea9cf8affd75abe5 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1040,7 +1040,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 
        /* TooBig packet may have updated dst->dev's mtu */
        if (!t->parms.collect_md && dst && dst_mtu(dst) > dst->dev->mtu)
-               dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu);
+               dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu, true);
 
        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
                           NEXTHDR_GRE);

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index b59940416cb5776c7a77910fef029aef8e9491e7..affb51c11a25b0beaddae3c13b1d74b86dfec042 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -95,7 +95,8 @@ static int            ip6_pkt_prohibit(struct sk_buff *skb);
 static int             ip6_pkt_prohibit_out(struct net *net, struct sock *sk, struct sk_buff *skb);
 static void            ip6_link_failure(struct sk_buff *skb);
 static void            ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                                          struct sk_buff *skb, u32 mtu);
+                                          struct sk_buff *skb, u32 mtu,
+                                          bool confirm_neigh);
 static void            rt6_do_redirect(struct dst_entry *dst, struct sock *sk,
                                        struct sk_buff *skb);
 static int rt6_score_route(const struct fib6_nh *nh, u32 fib6_flags, int oif,
@@ -264,7 +265,8 @@ static unsigned int ip6_blackhole_mtu(const struct dst_entry *dst)
 }
 
 static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                                        struct sk_buff *skb, u32 mtu)
+                                        struct sk_buff *skb, u32 mtu,
+                                        bool confirm_neigh)
 {
 }
 
@@ -2692,7 +2694,8 @@ static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
 }
 
 static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
-                                const struct ipv6hdr *iph, u32 mtu)
+                                const struct ipv6hdr *iph, u32 mtu,
+                                bool confirm_neigh)
 {
        const struct in6_addr *daddr, *saddr;
        struct rt6_info *rt6 = (struct rt6_info *)dst;
@@ -2710,7 +2713,10 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
                daddr = NULL;
                saddr = NULL;
        }
-       dst_confirm_neigh(dst, daddr);
+
+       if (confirm_neigh)
+               dst_confirm_neigh(dst, daddr);
+
        mtu = max_t(u32, mtu, IPV6_MIN_MTU);
        if (mtu >= dst_mtu(dst))
                return;
@@ -2764,9 +2770,11 @@ out_unlock:
 }
 
 static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                              struct sk_buff *skb, u32 mtu)
+                              struct sk_buff *skb, u32 mtu,
+                              bool confirm_neigh)
 {
-       __ip6_rt_update_pmtu(dst, sk, skb ? ipv6_hdr(skb) : NULL, mtu);
+       __ip6_rt_update_pmtu(dst, sk, skb ? ipv6_hdr(skb) : NULL, mtu,
+                            confirm_neigh);
 }
 
 void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
@@ -2785,7 +2793,7 @@ void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
 
        dst = ip6_route_output(net, NULL, &fl6);
        if (!dst->error)
-               __ip6_rt_update_pmtu(dst, NULL, iph, ntohl(mtu));
+               __ip6_rt_update_pmtu(dst, NULL, iph, ntohl(mtu), true);
        dst_release(dst);
 }
 EXPORT_SYMBOL_GPL(ip6_update_pmtu);

diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 699e0730ce8e86545ef2812da316f8e726e4a75d..af7a4b8b1e9c4a46a0b0cf4245a981efa24b9152 100644 (file)
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -98,12 +98,13 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 }
 
 static void xfrm6_update_pmtu(struct dst_entry *dst, struct sock *sk,
-                             struct sk_buff *skb, u32 mtu)
+                             struct sk_buff *skb, u32 mtu,
+                             bool confirm_neigh)
 {
        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
        struct dst_entry *path = xdst->route;
 
-       path->ops->update_pmtu(path, sk, skb, mtu);
+       path->ops->update_pmtu(path, sk, skb, mtu, confirm_neigh);
 }
 
 static void xfrm6_redirect(struct dst_entry *dst, struct sock *sk,

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index b1e300f8881b20dd8bc0c9bb2206ca911ab6bd73..b00866d777fe0e9ed8018087ebc664c56f29b5c9 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -208,7 +208,7 @@ static inline void maybe_update_pmtu(int skb_af, struct sk_buff *skb, int mtu)
        struct rtable *ort = skb_rtable(skb);
 
        if (!skb->dev && sk && sk_fullsock(sk))
-               ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu);
+               ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu, true);
 }
 
 static inline bool ensure_mtu_is_adequate(struct netns_ipvs *ipvs, int skb_af,

diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 7235a60326712186060ffc918b8cd14c596c2a3c..3bbe1a58ec876ec594256166c948ade2d9b4948b 100644 (file)
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -263,7 +263,7 @@ bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
 
                pf->af->from_sk(&addr, sk);
                pf->to_sk_daddr(&t->ipaddr, sk);
-               dst->ops->update_pmtu(dst, sk, NULL, pmtu);
+               dst->ops->update_pmtu(dst, sk, NULL, pmtu, true);
                pf->to_sk_daddr(&addr, sk);
 
                dst = sctp_transport_dst_check(t);