ipv4: Refactor fib_check_nh

fib_check_nh is currently huge covering multiple uses cases - device only,
device + gateway, and device + gateway with ONLINK. The next patch adds
validation checks for IPv6 which only further complicates it. So, break
fib_check_nh into 2 helpers - one for gateway validation and one for device
only.

Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 680b5a9a911a0493889cf4da895ec921d93e7e96..32ce6e6202d2fe5cff05249093cee52a9135300c 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -885,134 +885,150 @@ bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
  *                                     |
  *                                     |-> {local prefix} (terminal node)
  */
-static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
-                       struct netlink_ext_ack *extack)
+static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
+                             u8 scope, struct netlink_ext_ack *extack)
 {
-       int err = 0;
-       struct net *net;
        struct net_device *dev;
+       struct fib_result res;
+       int err;
 
-       net = cfg->fc_nlinfo.nl_net;
-       if (nh->fib_nh_gw4) {
-               struct fib_result res;
-
-               if (nh->fib_nh_flags & RTNH_F_ONLINK) {
-                       unsigned int addr_type;
+       if (nh->fib_nh_flags & RTNH_F_ONLINK) {
+               unsigned int addr_type;
 
-                       if (cfg->fc_scope >= RT_SCOPE_LINK) {
-                               NL_SET_ERR_MSG(extack,
-                                              "Nexthop has invalid scope");
-                               return -EINVAL;
-                       }
-                       dev = __dev_get_by_index(net, nh->fib_nh_oif);
-                       if (!dev) {
-                               NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
-                               return -ENODEV;
-                       }
-                       if (!(dev->flags & IFF_UP)) {
-                               NL_SET_ERR_MSG(extack,
-                                              "Nexthop device is not up");
-                               return -ENETDOWN;
-                       }
-                       addr_type = inet_addr_type_dev_table(net, dev,
-                                                            nh->fib_nh_gw4);
-                       if (addr_type != RTN_UNICAST) {
-                               NL_SET_ERR_MSG(extack,
-                                              "Nexthop has invalid gateway");
-                               return -EINVAL;
-                       }
-                       if (!netif_carrier_ok(dev))
-                               nh->fib_nh_flags |= RTNH_F_LINKDOWN;
-                       nh->fib_nh_dev = dev;
-                       dev_hold(dev);
-                       nh->fib_nh_scope = RT_SCOPE_LINK;
-                       return 0;
+               if (scope >= RT_SCOPE_LINK) {
+                       NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
+                       return -EINVAL;
                }
-               rcu_read_lock();
-               {
-                       struct fib_table *tbl = NULL;
-                       struct flowi4 fl4 = {
-                               .daddr = nh->fib_nh_gw4,
-                               .flowi4_scope = cfg->fc_scope + 1,
-                               .flowi4_oif = nh->fib_nh_oif,
-                               .flowi4_iif = LOOPBACK_IFINDEX,
-                       };
-
-                       /* It is not necessary, but requires a bit of thinking */
-                       if (fl4.flowi4_scope < RT_SCOPE_LINK)
-                               fl4.flowi4_scope = RT_SCOPE_LINK;
-
-                       if (cfg->fc_table)
-                               tbl = fib_get_table(net, cfg->fc_table);
-
-                       if (tbl)
-                               err = fib_table_lookup(tbl, &fl4, &res,
-                                                      FIB_LOOKUP_IGNORE_LINKSTATE |
-                                                      FIB_LOOKUP_NOREF);
-
-                       /* on error or if no table given do full lookup. This
-                        * is needed for example when nexthops are in the local
-                        * table rather than the given table
-                        */
-                       if (!tbl || err) {
-                               err = fib_lookup(net, &fl4, &res,
-                                                FIB_LOOKUP_IGNORE_LINKSTATE);
-                       }
-
-                       if (err) {
-                               NL_SET_ERR_MSG(extack,
-                                              "Nexthop has invalid gateway");
-                               rcu_read_unlock();
-                               return err;
-                       }
+               dev = __dev_get_by_index(net, nh->fib_nh_oif);
+               if (!dev) {
+                       NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
+                       return -ENODEV;
                }
-               err = -EINVAL;
-               if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
-                       NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
-                       goto out;
+               if (!(dev->flags & IFF_UP)) {
+                       NL_SET_ERR_MSG(extack, "Nexthop device is not up");
+                       return -ENETDOWN;
                }
-               nh->fib_nh_scope = res.scope;
-               nh->fib_nh_oif = FIB_RES_OIF(res);
-               nh->fib_nh_dev = dev = FIB_RES_DEV(res);
-               if (!dev) {
-                       NL_SET_ERR_MSG(extack,
-                                      "No egress device for nexthop gateway");
-                       goto out;
+               addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
+               if (addr_type != RTN_UNICAST) {
+                       NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
+                       return -EINVAL;
                }
-               dev_hold(dev);
                if (!netif_carrier_ok(dev))
                        nh->fib_nh_flags |= RTNH_F_LINKDOWN;
-               err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
-       } else {
-               struct in_device *in_dev;
-
-               if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
-                       NL_SET_ERR_MSG(extack,
-                                      "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
-                       return -EINVAL;
+               nh->fib_nh_dev = dev;
+               dev_hold(dev);
+               nh->fib_nh_scope = RT_SCOPE_LINK;
+               return 0;
+       }
+       rcu_read_lock();
+       {
+               struct fib_table *tbl = NULL;
+               struct flowi4 fl4 = {
+                       .daddr = nh->fib_nh_gw4,
+                       .flowi4_scope = scope + 1,
+                       .flowi4_oif = nh->fib_nh_oif,
+                       .flowi4_iif = LOOPBACK_IFINDEX,
+               };
+
+               /* It is not necessary, but requires a bit of thinking */
+               if (fl4.flowi4_scope < RT_SCOPE_LINK)
+                       fl4.flowi4_scope = RT_SCOPE_LINK;
+
+               if (table)
+                       tbl = fib_get_table(net, table);
+
+               if (tbl)
+                       err = fib_table_lookup(tbl, &fl4, &res,
+                                              FIB_LOOKUP_IGNORE_LINKSTATE |
+                                              FIB_LOOKUP_NOREF);
+
+               /* on error or if no table given do full lookup. This
+                * is needed for example when nexthops are in the local
+                * table rather than the given table
+                */
+               if (!tbl || err) {
+                       err = fib_lookup(net, &fl4, &res,
+                                        FIB_LOOKUP_IGNORE_LINKSTATE);
                }
-               rcu_read_lock();
-               err = -ENODEV;
-               in_dev = inetdev_by_index(net, nh->fib_nh_oif);
-               if (!in_dev)
-                       goto out;
-               err = -ENETDOWN;
-               if (!(in_dev->dev->flags & IFF_UP)) {
-                       NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
+
+               if (err) {
+                       NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
                        goto out;
                }
-               nh->fib_nh_dev = in_dev->dev;
-               dev_hold(nh->fib_nh_dev);
-               nh->fib_nh_scope = RT_SCOPE_HOST;
-               if (!netif_carrier_ok(nh->fib_nh_dev))
-                       nh->fib_nh_flags |= RTNH_F_LINKDOWN;
-               err = 0;
        }
+
+       err = -EINVAL;
+       if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
+               NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
+               goto out;
+       }
+       nh->fib_nh_scope = res.scope;
+       nh->fib_nh_oif = FIB_RES_OIF(res);
+       nh->fib_nh_dev = dev = FIB_RES_DEV(res);
+       if (!dev) {
+               NL_SET_ERR_MSG(extack,
+                              "No egress device for nexthop gateway");
+               goto out;
+       }
+       dev_hold(dev);
+       if (!netif_carrier_ok(dev))
+               nh->fib_nh_flags |= RTNH_F_LINKDOWN;
+       err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 out:
        rcu_read_unlock();
        return err;
 }
 
+static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
+                             struct netlink_ext_ack *extack)
+{
+       struct in_device *in_dev;
+       int err;
+
+       if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
+               NL_SET_ERR_MSG(extack,
+                              "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
+               return -EINVAL;
+       }
+
+       rcu_read_lock();
+
+       err = -ENODEV;
+       in_dev = inetdev_by_index(net, nh->fib_nh_oif);
+       if (!in_dev)
+               goto out;
+       err = -ENETDOWN;
+       if (!(in_dev->dev->flags & IFF_UP)) {
+               NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
+               goto out;
+       }
+
+       nh->fib_nh_dev = in_dev->dev;
+       dev_hold(nh->fib_nh_dev);
+       nh->fib_nh_scope = RT_SCOPE_HOST;
+       if (!netif_carrier_ok(nh->fib_nh_dev))
+               nh->fib_nh_flags |= RTNH_F_LINKDOWN;
+       err = 0;
+out:
+       rcu_read_unlock();
+       return err;
+}
+
+static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
+                       struct netlink_ext_ack *extack)
+{
+       struct net *net = cfg->fc_nlinfo.nl_net;
+       u32 table = cfg->fc_table;
+       int err;
+
+       if (nh->fib_nh_gw_family == AF_INET)
+               err = fib_check_nh_v4_gw(net, nh, table, cfg->fc_scope, extack);
+       else
+               err = fib_check_nh_nongw(net, nh, extack);
+
+       return err;
+}
+
 static inline unsigned int fib_laddr_hashfn(__be32 val)
 {
        unsigned int mask = (fib_info_hash_size - 1);