[PATCH v3 net-next 5/5] ipv4: tcp: give socket pointer to control skbs

[Eric Dumazet <edumazet@google.com>]

ip_send_unicast_reply() send orphaned 'control packets'.

These are RST packets and also ACK packets sent from TIME_WAIT.

Some eBPF programs would prefer to have a meaningful skb->sk
pointer as much as possible.

This means that TCP can now attach TIME_WAIT sockets to outgoing
skbs.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/ip.h     | 3 ++-
 net/ipv4/ip_output.c | 5 ++++-
 net/ipv4/tcp_ipv4.c  | 4 ++--
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index bab084df15677543b7400bb2832c0e83988884cb..4be0a6a603b2b5d5cfddc045a7d49d0d77be9570 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -288,7 +288,8 @@ static inline __u8 ip_reply_arg_flowi_flags(const struct ip_reply_arg *arg)
 	return (arg->flags & IP_REPLY_ARG_NOSRCCHECK) ? FLOWI_FLAG_ANYSRC : 0;
 }
 
-void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
+void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
+			   struct sk_buff *skb,
 			   const struct ip_options *sopt,
 			   __be32 daddr, __be32 saddr,
 			   const struct ip_reply_arg *arg,
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index e5c55a95063dd8340f9a014102408e859b4eb755..0065b1996c947078bea210c9abe5c80fa0e0ab4f 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1596,7 +1596,8 @@ static int ip_reply_glue_bits(void *dptr, char *to, int offset,
  *	Generic function to send a packet as reply to another packet.
  *	Used to send some TCP resets/acks so far.
  */
-void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
+void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
+			   struct sk_buff *skb,
 			   const struct ip_options *sopt,
 			   __be32 daddr, __be32 saddr,
 			   const struct ip_reply_arg *arg,
@@ -1662,6 +1663,8 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 			  arg->csumoffset) = csum_fold(csum_add(nskb->csum,
 								arg->csum));
 		nskb->ip_summed = CHECKSUM_NONE;
+		if (orig_sk)
+			skb_set_owner_edemux(nskb, (struct sock *)orig_sk);
 		if (transmit_time)
 			nskb->tstamp_type = SKB_CLOCK_MONOTONIC;
 		if (txhash)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 985028434f644c399e51d12ba8d9c2c5740dc6e1..9d3dd101ea713b14e13afe662baa49d21b3b716c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -907,7 +907,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb,
 		ctl_sk->sk_mark = 0;
 		ctl_sk->sk_priority = 0;
 	}
-	ip_send_unicast_reply(ctl_sk,
+	ip_send_unicast_reply(ctl_sk, sk,
 			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
 			      ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
 			      &arg, arg.iov[0].iov_len,
@@ -1021,7 +1021,7 @@ static void tcp_v4_send_ack(const struct sock *sk,
 	ctl_sk->sk_priority = (sk->sk_state == TCP_TIME_WAIT) ?
 			   inet_twsk(sk)->tw_priority : READ_ONCE(sk->sk_priority);
 	transmit_time = tcp_transmit_time(sk);
-	ip_send_unicast_reply(ctl_sk,
+	ip_send_unicast_reply(ctl_sk, sk,
 			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
 			      ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
 			      &arg, arg.iov[0].iov_len,
-- 
2.47.0.rc1.288.g06298d1525-goog