Add skb drop reasons to IPv6 UDP receive path

Enumerate the skb drop reasons in the receive path for IPv6 UDP packets.

Signed-off-by: Donald Hunter <donald.hunter@redhat.com>
Link: https://lore.kernel.org/r/20220926120350.14928-1-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 3366d6a77ff295675d1d5ac04723e0156053da1a..91e795bb9ade610c138e003ea2ffe326fa39def8 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -650,16 +650,20 @@ static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
        rc = __udp_enqueue_schedule_skb(sk, skb);
        if (rc < 0) {
                int is_udplite = IS_UDPLITE(sk);
+               enum skb_drop_reason drop_reason;
 
                /* Note that an ENOMEM error is charged twice */
-               if (rc == -ENOMEM)
+               if (rc == -ENOMEM) {
                        UDP6_INC_STATS(sock_net(sk),
                                         UDP_MIB_RCVBUFERRORS, is_udplite);
-               else
+                       drop_reason = SKB_DROP_REASON_SOCKET_RCVBUFF;
+               } else {
                        UDP6_INC_STATS(sock_net(sk),
                                       UDP_MIB_MEMERRORS, is_udplite);
+                       drop_reason = SKB_DROP_REASON_PROTO_MEM;
+               }
                UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
-               kfree_skb(skb);
+               kfree_skb_reason(skb, drop_reason);
                return -1;
        }
 
@@ -675,11 +679,14 @@ static __inline__ int udpv6_err(struct sk_buff *skb,
 
 static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 {
+       enum skb_drop_reason drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
        struct udp_sock *up = udp_sk(sk);
        int is_udplite = IS_UDPLITE(sk);
 
-       if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
+       if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
+               drop_reason = SKB_DROP_REASON_XFRM_POLICY;
                goto drop;
+       }
 
        if (static_branch_unlikely(&udpv6_encap_needed_key) && up->encap_type) {
                int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
@@ -738,8 +745,10 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
            udp_lib_checksum_complete(skb))
                goto csum_error;
 
-       if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr)))
+       if (sk_filter_trim_cap(sk, skb, sizeof(struct udphdr))) {
+               drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
                goto drop;
+       }
 
        udp_csum_pull_header(skb);
 
@@ -748,11 +757,12 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
        return __udpv6_queue_rcv_skb(sk, skb);
 
 csum_error:
+       drop_reason = SKB_DROP_REASON_UDP_CSUM;
        __UDP6_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
 drop:
        __UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
        atomic_inc(&sk->sk_drops);
-       kfree_skb(skb);
+       kfree_skb_reason(skb, drop_reason);
        return -1;
 }