Commit 643b622b authored by Menglong Dong's avatar Menglong Dong Committed by David S. Miller
Browse files

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: default avatarMengen Sun <mengensun@tencent.com>
Reviewed-by: default avatarHao Peng <flyingpeng@tencent.com>
Signed-off-by: default avatarMenglong Dong <imagedong@tencent.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c0e3154d

include/linux/skbuff.h

+12 −0
Original line number Diff line number Diff line
@@ -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,

};

include/trace/events/skb.h

+4 −0
Original line number Diff line number Diff line
@@ -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

net/ipv4/tcp_ipv4.c

+9 −4
Original line number Diff line number Diff line
@@ -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 @@ int tcp_v4_rcv(struct sk_buff *skb) 
		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 @@ int tcp_v4_rcv(struct sk_buff *skb) 
		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);

net/ipv6/tcp_ipv6.c

+8 −3
Original line number Diff line number Diff line
@@ -775,7 +775,8 @@ static int tcp_v6_md5_hash_skb(char *md5_hash, 


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 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) 
		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 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) 
		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)) {