Commit 71489e21 authored by Joe Stringer's avatar Joe Stringer Committed by Alexei Starovoitov
Browse files

net: Track socket refcounts in skb_steal_sock() 



Refactor the UDP/TCP handlers slightly to allow skb_steal_sock() to make
the determination of whether the socket is reference counted in the case
where it is prefetched by earlier logic such as early_demux.

Signed-off-by: default avatarJoe Stringer <joe@wand.net.nz>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-3-joe@wand.net.nz
parent cf7fbe66

include/net/inet6_hashtables.h

+1 −2
Original line number Diff line number Diff line
@@ -85,9 +85,8 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo, 
					      int iif, int sdif,

					      bool *refcounted)

{

	struct sock *sk = skb_steal_sock(skb);

	struct sock *sk = skb_steal_sock(skb, refcounted);



	*refcounted = true;

	if (sk)

		return sk;

include/net/inet_hashtables.h

+1 −2
Original line number Diff line number Diff line
@@ -379,10 +379,9 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo, 
					     const int sdif,

					     bool *refcounted)

{

	struct sock *sk = skb_steal_sock(skb);

	struct sock *sk = skb_steal_sock(skb, refcounted);

	const struct iphdr *iph = ip_hdr(skb);



	*refcounted = true;

	if (sk)

		return sk;

include/net/sock.h

+9 −1
Original line number Diff line number Diff line
@@ -2537,15 +2537,23 @@ skb_sk_is_prefetched(struct sk_buff *skb) 
#endif /* CONFIG_INET */

}



static inline struct sock *skb_steal_sock(struct sk_buff *skb)

/**

 * skb_steal_sock

 * @skb to steal the socket from

 * @refcounted is set to true if the socket is reference-counted

 */

static inline struct sock *

skb_steal_sock(struct sk_buff *skb, bool *refcounted)

{

	if (skb->sk) {

		struct sock *sk = skb->sk;



		*refcounted = true;

		skb->destructor = NULL;

		skb->sk = NULL;

		return sk;

	}

	*refcounted = false;

	return NULL;

}

net/ipv4/udp.c

+4 −2
Original line number Diff line number Diff line
@@ -2288,6 +2288,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
	struct rtable *rt = skb_rtable(skb);

	__be32 saddr, daddr;

	struct net *net = dev_net(skb->dev);

	bool refcounted;



	/*

	 *  Validate the packet.
@@ -2313,7 +2314,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
	if (udp4_csum_init(skb, uh, proto))

		goto csum_error;



	sk = skb_steal_sock(skb);

	sk = skb_steal_sock(skb, &refcounted);

	if (sk) {

		struct dst_entry *dst = skb_dst(skb);

		int ret;
@@ -2322,6 +2323,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
			udp_sk_rx_dst_set(sk, dst);



		ret = udp_unicast_rcv_skb(sk, skb, uh);

		if (refcounted)

			sock_put(sk);

		return ret;

	}

net/ipv6/udp.c

+6 −3
Original line number Diff line number Diff line
@@ -843,6 +843,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
	struct net *net = dev_net(skb->dev);

	struct udphdr *uh;

	struct sock *sk;

	bool refcounted;

	u32 ulen = 0;



	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
@@ -879,7 +880,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
		goto csum_error;



	/* Check if the socket is already available, e.g. due to early demux */

	sk = skb_steal_sock(skb);

	sk = skb_steal_sock(skb, &refcounted);

	if (sk) {

		struct dst_entry *dst = skb_dst(skb);

		int ret;
@@ -888,11 +889,13 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable, 
			udp6_sk_rx_dst_set(sk, dst);



		if (!uh->check && !udp_sk(sk)->no_check6_rx) {

			if (refcounted)

				sock_put(sk);

			goto report_csum_error;

		}



		ret = udp6_unicast_rcv_skb(sk, skb, uh);

		if (refcounted)

			sock_put(sk);

		return ret;

	}

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