net: ip: make ip_route_input_slow() return drop reasons

In this commit, we make ip_route_input_slow() return skb drop reasons,
and following new skb drop reasons are added:

  SKB_DROP_REASON_IP_INVALID_DEST

The only caller of ip_route_input_slow() is ip_route_input_rcu(), and we
adjust it by making it return -EINVAL on error.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index a2a1fb9..74624d3 100644 (file)
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -79,6 +79,7 @@
        FN(IP_LOCAL_SOURCE)             \
        FN(IP_INVALID_SOURCE)           \
        FN(IP_LOCALNET)                 \
+       FN(IP_INVALID_DEST)             \
        FN(PKT_TOO_BIG)                 \
        FN(DUP_FRAG)                    \
        FN(FRAG_REASM_TIMEOUT)          \
@@ -386,6 +387,11 @@ enum skb_drop_reason {
        SKB_DROP_REASON_IP_INVALID_SOURCE,
        /** @SKB_DROP_REASON_IP_LOCALNET: source or dest ip is local net */
        SKB_DROP_REASON_IP_LOCALNET,
+       /**
+        * @SKB_DROP_REASON_IP_INVALID_DEST: the dest ip is invalid:
+        * 1) dest ip is 0
+        */
+       SKB_DROP_REASON_IP_INVALID_DEST,
        /**
         * @SKB_DROP_REASON_PKT_TOO_BIG: packet size is too big (maybe exceed the
         * MTU)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ef0b5ff..b73f035 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2217,9 +2217,10 @@ static struct net_device *ip_rt_get_dev(struct net *net,
  *     called with rcu_read_lock()
  */
 
-static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-                              dscp_t dscp, struct net_device *dev,
-                              struct fib_result *res)
+static enum skb_drop_reason
+ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+                   dscp_t dscp, struct net_device *dev,
+                   struct fib_result *res)
 {
        enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
        struct in_device *in_dev = __in_dev_get_rcu(dev);
@@ -2249,8 +2250,10 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                fl4.flowi4_tun_key.tun_id = 0;
        skb_dst_drop(skb);
 
-       if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
+       if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr)) {
+               reason = SKB_DROP_REASON_IP_INVALID_SOURCE;
                goto martian_source;
+       }
 
        res->fi = NULL;
        res->table = NULL;
@@ -2260,21 +2263,29 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
        /* Accept zero addresses only to limited broadcast;
         * I even do not know to fix it or not. Waiting for complains :-)
         */
-       if (ipv4_is_zeronet(saddr))
+       if (ipv4_is_zeronet(saddr)) {
+               reason = SKB_DROP_REASON_IP_INVALID_SOURCE;
                goto martian_source;
+       }
 
-       if (ipv4_is_zeronet(daddr))
+       if (ipv4_is_zeronet(daddr)) {
+               reason = SKB_DROP_REASON_IP_INVALID_DEST;
                goto martian_destination;
+       }
 
        /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
         * and call it once if daddr or/and saddr are loopback addresses
         */
        if (ipv4_is_loopback(daddr)) {
-               if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
+               if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net)) {
+                       reason = SKB_DROP_REASON_IP_LOCALNET;
                        goto martian_destination;
+               }
        } else if (ipv4_is_loopback(saddr)) {
-               if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
+               if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net)) {
+                       reason = SKB_DROP_REASON_IP_LOCALNET;
                        goto martian_source;
+               }
        }
 
        /*
@@ -2329,19 +2340,26 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                err = -EHOSTUNREACH;
                goto no_route;
        }
-       if (res->type != RTN_UNICAST)
+       if (res->type != RTN_UNICAST) {
+               reason = SKB_DROP_REASON_IP_INVALID_DEST;
                goto martian_destination;
+       }
 
 make_route:
        err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, dscp, flkeys);
-out:   return err;
+       if (!err)
+               reason = SKB_NOT_DROPPED_YET;
+
+out:
+       return reason;
 
 brd_input:
-       if (skb->protocol != htons(ETH_P_IP))
-               goto e_inval;
+       if (skb->protocol != htons(ETH_P_IP)) {
+               reason = SKB_DROP_REASON_INVALID_PROTO;
+               goto out;
+       }
 
        if (!ipv4_is_zeronet(saddr)) {
-               err = -EINVAL;
                reason = fib_validate_source_reason(skb, saddr, 0, dscp, 0,
                                                    dev, in_dev, &itag);
                if (reason)
@@ -2362,7 +2380,7 @@ local_input:
                rth = rcu_dereference(nhc->nhc_rth_input);
                if (rt_cache_valid(rth)) {
                        skb_dst_set_noref(skb, &rth->dst);
-                       err = 0;
+                       reason = SKB_NOT_DROPPED_YET;
                        goto out;
                }
        }
@@ -2399,7 +2417,7 @@ local_input:
                        rt_add_uncached_list(rth);
        }
        skb_dst_set(skb, &rth->dst);
-       err = 0;
+       reason = SKB_NOT_DROPPED_YET;
        goto out;
 
 no_route:
@@ -2420,12 +2438,8 @@ martian_destination:
                                     &daddr, &saddr, dev->name);
 #endif
 
-e_inval:
-       err = -EINVAL;
-       goto out;
-
 e_nobufs:
-       err = -ENOBUFS;
+       reason = SKB_DROP_REASON_NOMEM;
        goto out;
 
 martian_source:
@@ -2482,7 +2496,7 @@ static int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                return reason ? -EINVAL : 0;
        }
 
-       return ip_route_input_slow(skb, daddr, saddr, dscp, dev, res);
+       return ip_route_input_slow(skb, daddr, saddr, dscp, dev, res) ? -EINVAL : 0;
 }
 
 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,