vxlan: improve validation of address family configuration

Address families of source and destination addresses must match, and
changelink operations can't change the address family.

In addition, always use the VXLAN_F_IPV6 to check if a VXLAN device uses
IPv4 or IPv6.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index b4fce3b..00680cc 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2484,10 +2484,7 @@ static int vxlan_change_mtu(struct net_device *dev, int new_mtu)
        struct vxlan_rdst *dst = &vxlan->default_dst;
        struct net_device *lowerdev = __dev_get_by_index(vxlan->net,
                                                         dst->remote_ifindex);
-       bool use_ipv6 = false;
-
-       if (dst->remote_ip.sa.sa_family == AF_INET6)
-               use_ipv6 = true;
+       bool use_ipv6 = !!(vxlan->cfg.flags & VXLAN_F_IPV6);
 
        /* This check is different than dev->max_mtu, because it looks at
         * the lowerdev->mtu, rather than the static dev->max_mtu
@@ -2897,11 +2894,20 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
                }
        }
 
-       if (!conf->remote_ip.sa.sa_family)
+       if (!conf->remote_ip.sa.sa_family && !conf->saddr.sa.sa_family) {
+               /* Unless IPv6 is explicitly requested, assume IPv4 */
                conf->remote_ip.sa.sa_family = AF_INET;
+               conf->saddr.sa.sa_family = AF_INET;
+       } else if (!conf->remote_ip.sa.sa_family) {
+               conf->remote_ip.sa.sa_family = conf->saddr.sa.sa_family;
+       } else if (!conf->saddr.sa.sa_family) {
+               conf->saddr.sa.sa_family = conf->remote_ip.sa.sa_family;
+       }
+
+       if (conf->saddr.sa.sa_family != conf->remote_ip.sa.sa_family)
+               return -EINVAL;
 
-       if (conf->remote_ip.sa.sa_family == AF_INET6 ||
-           conf->saddr.sa.sa_family == AF_INET6) {
+       if (conf->saddr.sa.sa_family == AF_INET6) {
                if (!IS_ENABLED(CONFIG_IPV6))
                        return -EPFNOSUPPORT;
                use_ipv6 = true;
@@ -2949,11 +2955,9 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
                        continue;
 
                if (tmp->cfg.vni == conf->vni &&
-                   (tmp->default_dst.remote_ip.sa.sa_family == AF_INET6 ||
-                    tmp->cfg.saddr.sa.sa_family == AF_INET6) == use_ipv6 &&
                    tmp->cfg.dst_port == conf->dst_port &&
-                   (tmp->cfg.flags & VXLAN_F_RCV_FLAGS) ==
-                   (conf->flags & VXLAN_F_RCV_FLAGS))
+                   (tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) ==
+                   (conf->flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)))
                        return -EEXIST;
        }
 
@@ -3084,22 +3088,35 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
        }
 
        if (data[IFLA_VXLAN_GROUP]) {
+               if (changelink && (conf->remote_ip.sa.sa_family != AF_INET))
+                       return -EOPNOTSUPP;
+
                conf->remote_ip.sin.sin_addr.s_addr = nla_get_in_addr(data[IFLA_VXLAN_GROUP]);
+               conf->remote_ip.sa.sa_family = AF_INET;
        } else if (data[IFLA_VXLAN_GROUP6]) {
                if (!IS_ENABLED(CONFIG_IPV6))
                        return -EPFNOSUPPORT;
 
+               if (changelink && (conf->remote_ip.sa.sa_family != AF_INET6))
+                       return -EOPNOTSUPP;
+
                conf->remote_ip.sin6.sin6_addr = nla_get_in6_addr(data[IFLA_VXLAN_GROUP6]);
                conf->remote_ip.sa.sa_family = AF_INET6;
        }
 
        if (data[IFLA_VXLAN_LOCAL]) {
+               if (changelink && (conf->saddr.sa.sa_family != AF_INET))
+                       return -EOPNOTSUPP;
+
                conf->saddr.sin.sin_addr.s_addr = nla_get_in_addr(data[IFLA_VXLAN_LOCAL]);
                conf->saddr.sa.sa_family = AF_INET;
        } else if (data[IFLA_VXLAN_LOCAL6]) {
                if (!IS_ENABLED(CONFIG_IPV6))
                        return -EPFNOSUPPORT;
 
+               if (changelink && (conf->saddr.sa.sa_family != AF_INET6))
+                       return -EOPNOTSUPP;
+
                /* TODO: respect scope id */
                conf->saddr.sin6.sin6_addr = nla_get_in6_addr(data[IFLA_VXLAN_LOCAL6]);
                conf->saddr.sa.sa_family = AF_INET6;