net: ip: make ip_route_input_noref() return drop reasons

In this commit, we make ip_route_input_noref() return drop reasons, which
come from ip_route_input_rcu().

We need adjust the callers of ip_route_input_noref() to make sure the
return value of ip_route_input_noref() is used properly.

The errno that ip_route_input_noref() returns comes from ip_route_input
and bpf_lwt_input_reroute in the origin logic, and we make them return
-EINVAL on error instead. In the following patch, we will make
ip_route_input() returns drop reasons too.

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

diff --git a/include/net/route.h b/include/net/route.h
index e2e1922..b85ffa3 100644 (file)
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -203,8 +203,9 @@ enum skb_drop_reason
 ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                      dscp_t dscp, struct net_device *dev,
                      struct in_device *in_dev, u32 *itag);
-int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-                        dscp_t dscp, struct net_device *dev);
+enum skb_drop_reason
+ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+                    dscp_t dscp, struct net_device *dev);
 int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                      dscp_t dscp, struct net_device *dev,
                      const struct sk_buff *hint);
@@ -212,18 +213,18 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
                                 dscp_t dscp, struct net_device *devin)
 {
-       int err;
+       enum skb_drop_reason reason;
 
        rcu_read_lock();
-       err = ip_route_input_noref(skb, dst, src, dscp, devin);
-       if (!err) {
+       reason = ip_route_input_noref(skb, dst, src, dscp, devin);
+       if (!reason) {
                skb_dst_force(skb);
                if (!skb_dst(skb))
-                       err = -EINVAL;
+                       reason = SKB_DROP_REASON_NOT_SPECIFIED;
        }
        rcu_read_unlock();
 
-       return err;
+       return reason ? -EINVAL : 0;
 }
 
 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,

diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index e0ca24a..8a78bff 100644 (file)
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -88,6 +88,7 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
 
 static int bpf_lwt_input_reroute(struct sk_buff *skb)
 {
+       enum skb_drop_reason reason;
        int err = -EINVAL;
 
        if (skb->protocol == htons(ETH_P_IP)) {
@@ -96,8 +97,9 @@ static int bpf_lwt_input_reroute(struct sk_buff *skb)
 
                dev_hold(dev);
                skb_dst_drop(skb);
-               err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
-                                          ip4h_dscp(iph), dev);
+               reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+                                             ip4h_dscp(iph), dev);
+               err = reason ? -EINVAL : 0;
                dev_put(dev);
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                skb_dst_drop(skb);

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 48e2810..07036a2 100644 (file)
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -132,12 +132,12 @@ static bool frag_expire_skip_icmp(u32 user)
  */
 static void ip_expire(struct timer_list *t)
 {
+       enum skb_drop_reason reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
        struct inet_frag_queue *frag = from_timer(frag, t, timer);
        const struct iphdr *iph;
        struct sk_buff *head = NULL;
        struct net *net;
        struct ipq *qp;
-       int err;
 
        qp = container_of(frag, struct ipq, q);
        net = qp->q.fqdir->net;
@@ -175,14 +175,15 @@ static void ip_expire(struct timer_list *t)
 
        /* skb has no dst, perform route lookup again */
        iph = ip_hdr(head);
-       err = ip_route_input_noref(head, iph->daddr, iph->saddr, ip4h_dscp(iph),
-                                  head->dev);
-       if (err)
+       reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
+                                     ip4h_dscp(iph), head->dev);
+       if (reason)
                goto out;
 
        /* Only an end host needs to send an ICMP
         * "Fragment Reassembly Timeout" message, per RFC792.
         */
+       reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
        if (frag_expire_skip_icmp(qp->q.key.v4.user) &&
            (skb_rtable(head)->rt_type != RTN_LOCAL))
                goto out;
@@ -195,7 +196,7 @@ out:
        spin_unlock(&qp->q.lock);
 out_rcu_unlock:
        rcu_read_unlock();
-       kfree_skb_reason(head, SKB_DROP_REASON_FRAG_REASM_TIMEOUT);
+       kfree_skb_reason(head, reason);
        ipq_put(qp);
 }
 

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c40a269..513eb0c 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -362,10 +362,11 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
         *      how the packet travels inside Linux networking.
         */
        if (!skb_valid_dst(skb)) {
-               err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
-                                          ip4h_dscp(iph), dev);
-               if (unlikely(err))
+               drop_reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+                                                  ip4h_dscp(iph), dev);
+               if (unlikely(drop_reason))
                        goto drop_error;
+               drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
        } else {
                struct in_device *in_dev = __in_dev_get_rcu(dev);
 

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 270bc8c..5a7edb6 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2500,8 +2500,9 @@ ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
        return ip_route_input_slow(skb, daddr, saddr, dscp, dev, res);
 }
 
-int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-                        dscp_t dscp, struct net_device *dev)
+enum skb_drop_reason ip_route_input_noref(struct sk_buff *skb, __be32 daddr,
+                                         __be32 saddr, dscp_t dscp,
+                                         struct net_device *dev)
 {
        enum skb_drop_reason reason;
        struct fib_result res;
@@ -2510,7 +2511,7 @@ int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
        reason = ip_route_input_rcu(skb, daddr, saddr, dscp, dev, &res);
        rcu_read_unlock();
 
-       return reason ? -EINVAL : 0;
+       return reason;
 }
 EXPORT_SYMBOL(ip_route_input_noref);