net: tcp: add skb drop reasons to tcp_v{4,6}_inbound_md5_hash()

Pass the address of drop reason to tcp_v4_inbound_md5_hash() and
tcp_v6_inbound_md5_hash() to store the reasons for skb drops when this
function fails. Therefore, the drop reason can be passed to
kfree_skb_reason() when the skb needs to be freed.

Following drop reasons are added:

SKB_DROP_REASON_TCP_MD5NOTFOUND
SKB_DROP_REASON_TCP_MD5UNEXPECTED
SKB_DROP_REASON_TCP_MD5FAILURE

SKB_DROP_REASON_TCP_MD5* above correspond to LINUX_MIB_TCPMD5*

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a5adbf6..46678eb 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -346,6 +346,18 @@ enum skb_drop_reason {
                                         * udp packet drop out of
                                         * udp_memory_allocated.
                                         */
+       SKB_DROP_REASON_TCP_MD5NOTFOUND,        /* no MD5 hash and one
+                                                * expected, corresponding
+                                                * to LINUX_MIB_TCPMD5NOTFOUND
+                                                */
+       SKB_DROP_REASON_TCP_MD5UNEXPECTED,      /* MD5 hash and we're not
+                                                * expecting one, corresponding
+                                                * to LINUX_MIB_TCPMD5UNEXPECTED
+                                                */
+       SKB_DROP_REASON_TCP_MD5FAILURE, /* MD5 hash and its wrong,
+                                        * corresponding to
+                                        * LINUX_MIB_TCPMD5FAILURE
+                                        */
        SKB_DROP_REASON_MAX,
 };
 

diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index cfcfd26..46c06b0 100644 (file)
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -27,6 +27,10 @@
        EM(SKB_DROP_REASON_IP_NOPROTO, IP_NOPROTO)              \
        EM(SKB_DROP_REASON_SOCKET_RCVBUFF, SOCKET_RCVBUFF)      \
        EM(SKB_DROP_REASON_PROTO_MEM, PROTO_MEM)                \
+       EM(SKB_DROP_REASON_TCP_MD5NOTFOUND, TCP_MD5NOTFOUND)    \
+       EM(SKB_DROP_REASON_TCP_MD5UNEXPECTED,                   \
+          TCP_MD5UNEXPECTED)                                   \
+       EM(SKB_DROP_REASON_TCP_MD5FAILURE, TCP_MD5FAILURE)      \
        EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a3beab0..d3c4171 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1412,7 +1412,8 @@ EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
 /* Called with rcu_read_lock() */
 static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
                                    const struct sk_buff *skb,
-                                   int dif, int sdif)
+                                   int dif, int sdif,
+                                   enum skb_drop_reason *reason)
 {
 #ifdef CONFIG_TCP_MD5SIG
        /*
@@ -1445,11 +1446,13 @@ static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
                return false;
 
        if (hash_expected && !hash_location) {
+               *reason = SKB_DROP_REASON_TCP_MD5NOTFOUND;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
                return true;
        }
 
        if (!hash_expected && hash_location) {
+               *reason = SKB_DROP_REASON_TCP_MD5UNEXPECTED;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
                return true;
        }
@@ -1462,6 +1465,7 @@ static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
                                      NULL, skb);
 
        if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+               *reason = SKB_DROP_REASON_TCP_MD5FAILURE;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
                net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s L3 index %d\n",
                                     &iph->saddr, ntohs(th->source),
@@ -1971,13 +1975,13 @@ static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph,
 int tcp_v4_rcv(struct sk_buff *skb)
 {
        struct net *net = dev_net(skb->dev);
+       enum skb_drop_reason drop_reason;
        int sdif = inet_sdif(skb);
        int dif = inet_iif(skb);
        const struct iphdr *iph;
        const struct tcphdr *th;
        bool refcounted;
        struct sock *sk;
-       int drop_reason;
        int ret;
 
        drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
@@ -2025,7 +2029,8 @@ process:
                struct sock *nsk;
 
                sk = req->rsk_listener;
-               if (unlikely(tcp_v4_inbound_md5_hash(sk, skb, dif, sdif))) {
+               if (unlikely(tcp_v4_inbound_md5_hash(sk, skb, dif, sdif,
+                                                    &drop_reason))) {
                        sk_drops_add(sk, skb);
                        reqsk_put(req);
                        goto discard_it;
@@ -2099,7 +2104,7 @@ process:
                goto discard_and_relse;
        }
 
-       if (tcp_v4_inbound_md5_hash(sk, skb, dif, sdif))
+       if (tcp_v4_inbound_md5_hash(sk, skb, dif, sdif, &drop_reason))
                goto discard_and_relse;
 
        nf_reset_ct(skb);

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0aa1707..1262b79 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -775,7 +775,8 @@ clear_hash_noput:
 
 static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
                                    const struct sk_buff *skb,
-                                   int dif, int sdif)
+                                   int dif, int sdif,
+                                   enum skb_drop_reason *reason)
 {
 #ifdef CONFIG_TCP_MD5SIG
        const __u8 *hash_location = NULL;
@@ -798,11 +799,13 @@ static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
                return false;
 
        if (hash_expected && !hash_location) {
+               *reason = SKB_DROP_REASON_TCP_MD5NOTFOUND;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
                return true;
        }
 
        if (!hash_expected && hash_location) {
+               *reason = SKB_DROP_REASON_TCP_MD5UNEXPECTED;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
                return true;
        }
@@ -813,6 +816,7 @@ static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
                                      NULL, skb);
 
        if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+               *reason = SKB_DROP_REASON_TCP_MD5FAILURE;
                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
                net_info_ratelimited("MD5 Hash %s for [%pI6c]:%u->[%pI6c]:%u L3 index %d\n",
                                     genhash ? "failed" : "mismatch",
@@ -1681,7 +1685,8 @@ process:
                struct sock *nsk;
 
                sk = req->rsk_listener;
-               if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif)) {
+               if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif,
+                                           &drop_reason)) {
                        sk_drops_add(sk, skb);
                        reqsk_put(req);
                        goto discard_it;
@@ -1752,7 +1757,7 @@ process:
                goto discard_and_relse;
        }
 
-       if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif))
+       if (tcp_v6_inbound_md5_hash(sk, skb, dif, sdif, &drop_reason))
                goto discard_and_relse;
 
        if (tcp_filter(sk, skb)) {