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>

4 files changed, 6 insertions, 5 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index cc7ef0d05bbd..5eb73775c3f7 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
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 9d24ef5c5d8f..535427292194 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -781,7 +781,7 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
         } else if (!ipc.oif)
                 ipc.oif = inet->uc_index;
 
-        flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
+        flowi4_init_output(&fl4, ipc.oif, ipc.sockc.mark, tos,
                            RT_SCOPE_UNIVERSE, sk->sk_protocol,
                            inet_sk_flowi_flags(sk), faddr, saddr, 0, 0,
                            sk->sk_uid);
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 40a6abbc9cf6..80da5a66d5d7 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -375,7 +375,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
         skb_reserve(skb, hlen);
 
         skb->priority = sk->sk_priority;
-        skb->mark = sk->sk_mark;
+        skb->mark = sockc->mark;
         skb->tstamp = sockc->transmit_time;
         skb_dst_set(skb, &rt->dst);
         *rtp = NULL;
@@ -623,7 +623,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                 }
         }
 
-        flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
+        flowi4_init_output(&fl4, ipc.oif, ipc.sockc.mark, tos,
                            RT_SCOPE_UNIVERSE,
                            hdrincl ? IPPROTO_RAW : sk->sk_protocol,
                            inet_sk_flowi_flags(sk) |
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d88821c794fb..fbcd9be3a470 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1130,7 +1130,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
                 fl4 = &fl4_stack;
 
-                flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
+                flowi4_init_output(fl4, ipc.oif, ipc.sockc.mark, tos,
                                    RT_SCOPE_UNIVERSE, sk->sk_protocol,
                                    flow_flags,
                                    faddr, saddr, dport, inet->inet_sport,