Commit 5ced52fa authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: add skb_set_owner_edemux() helper 



This can be used to attach a socket to an skb,
taking a reference on sk->sk_refcnt.

This helper might be a NOP if sk->sk_refcnt is zero.

Use it from tcp_make_synack().

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarBrian Vazquez <brianvv@google.com>
Link: https://patch.msgid.link/20241010174817.1543642-4-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent bc43a3c8

include/net/sock.h

+9 −0
Original line number Diff line number Diff line
@@ -1760,6 +1760,15 @@ void sock_efree(struct sk_buff *skb); 
#ifdef CONFIG_INET

void sock_edemux(struct sk_buff *skb);

void sock_pfree(struct sk_buff *skb);



static inline void skb_set_owner_edemux(struct sk_buff *skb, struct sock *sk)

{

	skb_orphan(skb);

	if (refcount_inc_not_zero(&sk->sk_refcnt)) {

		skb->sk = sk;

		skb->destructor = sock_edemux;

	}

}

#else

#define sock_edemux sock_efree

#endif

net/core/sock.c

+3 −6
Original line number Diff line number Diff line
@@ -2592,14 +2592,11 @@ void __sock_wfree(struct sk_buff *skb) 
void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)

{

	skb_orphan(skb);

	skb->sk = sk;

#ifdef CONFIG_INET

	if (unlikely(!sk_fullsock(sk))) {

		skb->destructor = sock_edemux;

		sock_hold(sk);

		return;

	}

	if (unlikely(!sk_fullsock(sk)))

		return skb_set_owner_edemux(skb, sk);

#endif

	skb->sk = sk;

	skb->destructor = sock_wfree;

	skb_set_hash_from_sk(skb, sk);

	/*

net/ipv4/tcp_output.c

+1 −1
Original line number Diff line number Diff line
@@ -3728,7 +3728,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 


	switch (synack_type) {

	case TCP_SYNACK_NORMAL:

		skb_set_owner_w(skb, req_to_sk(req));

		skb_set_owner_edemux(skb, req_to_sk(req));

		break;

	case TCP_SYNACK_COOKIE:

		/* Under synflood, we do not attach skb to a socket,