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ipv4: tcp: give socket pointer to control skbs
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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>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Brian Vazquez <brianvv@google.com>
Link: https://patch.msgid.link/20241010174817.1543642-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Eric Dumazet authored and Jakub Kicinski committed Oct 15, 2024
1 parent 507a967 commit 7963603
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Showing 3 changed files with 8 additions and 4 deletions.
3 changes: 2 additions & 1 deletion include/net/ip.h
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down
5 changes: 4 additions & 1 deletion net/ipv4/ip_output.c
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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)
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4 changes: 2 additions & 2 deletions net/ipv4/tcp_ipv4.c
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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,
Expand Down

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