5 files changed, 38 insertions, 18 deletions

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 7b85ffad5d74..f3db1f35a79d 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -1117,7 +1117,12 @@ int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
                 eth_hw_addr_random(dev);
 
         mtu = ip_tunnel_bind_dev(dev);
-        if (!tb[IFLA_MTU]) {
+        if (tb[IFLA_MTU]) {
+                unsigned int max = 0xfff8 - dev->hard_header_len - nt->hlen;
+
+                dev->mtu = clamp(dev->mtu, (unsigned int)ETH_MIN_MTU,
+                                 (unsigned int)(max - sizeof(struct iphdr)));
+        } else {
                 err = dev_set_mtu(dev, mtu);
                 if (err)
                         goto err_dev_set_mtu;
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 51b1669334fe..3f091ccad9af 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -387,8 +387,6 @@ static int vti_tunnel_init(struct net_device *dev)
         memcpy(dev->dev_addr, &iph->saddr, 4);
         memcpy(dev->broadcast, &iph->daddr, 4);
 
-        dev->hard_header_len    = LL_MAX_HEADER + sizeof(struct iphdr);
-        dev->mtu                = ETH_DATA_LEN;
         dev->flags              = IFF_NOARP;
         dev->addr_len           = 4;
         dev->features           |= NETIF_F_LLTX;
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index fa3ae1cb50d3..ce18cd20389d 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -622,11 +622,12 @@ static int vti6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
         return 0;
 }
 
-static void vti6_link_config(struct ip6_tnl *t)
+static void vti6_link_config(struct ip6_tnl *t, bool keep_mtu)
 {
         struct net_device *dev = t->dev;
         struct __ip6_tnl_parm *p = &t->parms;
         struct net_device *tdev = NULL;
+        int mtu;
 
         memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
         memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr));
@@ -640,6 +641,11 @@ static void vti6_link_config(struct ip6_tnl *t)
         else
                 dev->flags &= ~IFF_POINTOPOINT;
 
+        if (keep_mtu && dev->mtu) {
+                dev->mtu = clamp(dev->mtu, dev->min_mtu, dev->max_mtu);
+                return;
+        }
+
         if (p->flags & IP6_TNL_F_CAP_XMIT) {
                 int strict = (ipv6_addr_type(&p->raddr) &
                               (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
@@ -656,20 +662,25 @@ static void vti6_link_config(struct ip6_tnl *t)
                 tdev = __dev_get_by_index(t->net, p->link);
 
         if (tdev)
-                dev->mtu = max_t(int, tdev->mtu - dev->hard_header_len,
-                                 IPV6_MIN_MTU);
+                mtu = tdev->mtu - sizeof(struct ipv6hdr);
+        else
+                mtu = ETH_DATA_LEN - LL_MAX_HEADER - sizeof(struct ipv6hdr);
+
+        dev->mtu = max_t(int, mtu, IPV6_MIN_MTU);
 }
 
 /**
  * vti6_tnl_change - update the tunnel parameters
  *   @t: tunnel to be changed
  *   @p: tunnel configuration parameters
+ *   @keep_mtu: MTU was set from userspace, don't re-compute it
  *
  * Description:
  *   vti6_tnl_change() updates the tunnel parameters
  **/
 static int
-vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
+vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p,
+                bool keep_mtu)
 {
         t->parms.laddr = p->laddr;
         t->parms.raddr = p->raddr;
@@ -679,11 +690,12 @@ vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
         t->parms.proto = p->proto;
         t->parms.fwmark = p->fwmark;
         dst_cache_reset(&t->dst_cache);
-        vti6_link_config(t);
+        vti6_link_config(t, keep_mtu);
         return 0;
 }
 
-static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
+static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p,
+                       bool keep_mtu)
 {
         struct net *net = dev_net(t->dev);
         struct vti6_net *ip6n = net_generic(net, vti6_net_id);
@@ -691,7 +703,7 @@ static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
 
         vti6_tnl_unlink(ip6n, t);
         synchronize_net();
-        err = vti6_tnl_change(t, p);
+        err = vti6_tnl_change(t, p, keep_mtu);
         vti6_tnl_link(ip6n, t);
         netdev_state_change(t->dev);
         return err;
@@ -804,7 +816,7 @@ vti6_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
                         } else
                                 t = netdev_priv(dev);
 
-                        err = vti6_update(t, &p1);
+                        err = vti6_update(t, &p1, false);
                 }
                 if (t) {
                         err = 0;
@@ -866,10 +878,8 @@ static void vti6_dev_setup(struct net_device *dev)
         dev->priv_destructor = vti6_dev_free;
 
         dev->type = ARPHRD_TUNNEL6;
-        dev->hard_header_len = LL_MAX_HEADER + sizeof(struct ipv6hdr);
-        dev->mtu = ETH_DATA_LEN;
         dev->min_mtu = IPV6_MIN_MTU;
-        dev->max_mtu = IP_MAX_MTU;
+        dev->max_mtu = IP_MAX_MTU - sizeof(struct ipv6hdr);
         dev->flags |= IFF_NOARP;
         dev->addr_len = sizeof(struct in6_addr);
         netif_keep_dst(dev);
@@ -905,7 +915,7 @@ static int vti6_dev_init(struct net_device *dev)
 
         if (err)
                 return err;
-        vti6_link_config(t);
+        vti6_link_config(t, true);
         return 0;
 }
 
@@ -1010,7 +1020,7 @@ static int vti6_changelink(struct net_device *dev, struct nlattr *tb[],
         } else
                 t = netdev_priv(dev);
 
-        return vti6_update(t, &p);
+        return vti6_update(t, &p, tb && tb[IFLA_MTU]);
 }
 
 static size_t vti6_get_size(const struct net_device *dev)
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 1472c0857975..81788105c164 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -26,6 +26,12 @@ struct xfrm_trans_tasklet {
 };
 
 struct xfrm_trans_cb {
+        union {
+                struct inet_skb_parm    h4;
+#if IS_ENABLED(CONFIG_IPV6)
+                struct inet6_skb_parm   h6;
+#endif
+        } header;
         int (*finish)(struct net *net, struct sock *sk, struct sk_buff *skb);
 };
 
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 23468672a767..89b178a78dc7 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -285,8 +285,9 @@ void xfrm_local_error(struct sk_buff *skb, int mtu)
                 return;
 
         afinfo = xfrm_state_get_afinfo(proto);
-        if (afinfo)
+        if (afinfo) {
                 afinfo->local_error(skb, mtu);
-        rcu_read_unlock();
+                rcu_read_unlock();
+        }
 }
 EXPORT_SYMBOL_GPL(xfrm_local_error);