ip: support SO_MARK cmsg
Enable setting skb->mark for UDP and RAW sockets using cmsg.
This is analogous to existing support for TOS, TTL, txtime, etc.
Packet sockets already support this as of commit c7d39e32632e
("packet: support per-packet fwmark for af_packet sendmsg").
Similar to other fields, implement by
1. initialize the sockcm_cookie.mark from socket option sk_mark
2. optionally overwrite this in ip_cmsg_send/ip6_datagram_send_ctl
3. initialize inet_cork.mark from sockcm_cookie.mark
4. initialize each (usually just one) skb->mark from inet_cork.mark
Step 1 is handled in one location for most protocols by ipcm_init_sk
as of commit 351782067b6b ("ipv4: ipcm_cookie initializers").
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index cc7ef0d..5eb7377 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1266,6 +1266,7 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
cork->length = 0;
cork->ttl = ipc->ttl;
cork->tos = ipc->tos;
+ cork->mark = ipc->sockc.mark;
cork->priority = ipc->priority;
cork->transmit_time = ipc->sockc.transmit_time;
cork->tx_flags = 0;
@@ -1529,7 +1530,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
}
skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
- skb->mark = sk->sk_mark;
+ skb->mark = cork->mark;
skb->tstamp = cork->transmit_time;
/*
* Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec