sctp: add support for dscp and flowlabel per transport

Like some other per transport params, flowlabel and dscp are added
in transport, asoc and sctp_sock. By default, transport sets its
value from asoc's, and asoc does it from sctp_sock. flowlabel
only works for ipv6 transport.

Other than that they need to be passed down in sctp_xmit, flow4/6
also needs to set them before looking up route in get_dst.

Note that it uses '& 0x100000' to check if flowlabel is set and
'& 0x1' (tos 1st bit is unused) to check if dscp is set by users,
so that they could be set to 0 by sockopt in next patch.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 44 insertions, 6 deletions

diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index b36c76635f18..83d94341e003 100644
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -801,4 +801,11 @@ struct sctp_strreset_resptsn {
         __be32 receivers_next_tsn;
 };
 
+enum {
+        SCTP_DSCP_SET_MASK = 0x1,
+        SCTP_DSCP_VAL_MASK = 0xfc,
+        SCTP_FLOWLABEL_SET_MASK = 0x100000,
+        SCTP_FLOWLABEL_VAL_MASK = 0xfffff
+};
+
 #endif /* __LINUX_SCTP_H__ */
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 701a51736fa5..ab869e0d8326 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -193,6 +193,9 @@ struct sctp_sock {
         /* This is the max_retrans value for new associations. */
         __u16 pathmaxrxt;
 
+        __u32 flowlabel;
+        __u8  dscp;
+
         /* The initial Path MTU to use for new associations. */
         __u32 pathmtu;
 
@@ -895,6 +898,9 @@ struct sctp_transport {
          */
         __u16 pathmaxrxt;
 
+        __u32 flowlabel;
+        __u8  dscp;
+
         /* This is the partially failed retrans value for the transport
          * and will be initialized from the assocs value.  This can be changed
          * using the SCTP_PEER_ADDR_THLDS socket option
@@ -1772,6 +1778,9 @@ struct sctp_association {
          */
         __u16 pathmaxrxt;
 
+        __u32 flowlabel;
+        __u8  dscp;
+
         /* Flag that path mtu update is pending */
         __u8   pmtu_pending;
 
diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 5d5a16204d50..16ecfbc95614 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -115,6 +115,9 @@ static struct sctp_association *sctp_association_init(
         /* Initialize path max retrans value. */
         asoc->pathmaxrxt = sp->pathmaxrxt;
 
+        asoc->flowlabel = sp->flowlabel;
+        asoc->dscp = sp->dscp;
+
         /* Initialize default path MTU. */
         asoc->pathmtu = sp->pathmtu;
 
@@ -647,6 +650,10 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
         peer->sackdelay = asoc->sackdelay;
         peer->sackfreq = asoc->sackfreq;
 
+        if (addr->sa.sa_family == AF_INET6)
+                peer->flowlabel = asoc->flowlabel;
+        peer->dscp = asoc->dscp;
+
         /* Enable/disable heartbeat, SACK delay, and path MTU discovery
          * based on association setting.
          */
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 0cd2e764f47f..38102bf7f13e 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -209,12 +209,17 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport)
         struct sock *sk = skb->sk;
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct flowi6 *fl6 = &transport->fl.u.ip6;
+        __u8 tclass = np->tclass;
         int res;
 
         pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n", __func__, skb,
                  skb->len, &fl6->saddr, &fl6->daddr);
 
-        IP6_ECN_flow_xmit(sk, fl6->flowlabel);
+        if (transport->dscp & SCTP_DSCP_SET_MASK)
+                tclass = transport->dscp & SCTP_DSCP_VAL_MASK;
+
+        if (INET_ECN_is_capable(tclass))
+                IP6_ECN_flow_xmit(sk, fl6->flowlabel);
 
         if (!(transport->param_flags & SPP_PMTUD_ENABLE))
                 skb->ignore_df = 1;
@@ -223,7 +228,7 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport)
 
         rcu_read_lock();
         res = ip6_xmit(sk, skb, fl6, sk->sk_mark, rcu_dereference(np->opt),
-                       np->tclass);
+                       tclass);
         rcu_read_unlock();
         return res;
 }
@@ -254,6 +259,8 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                 fl6->flowi6_oif = daddr->v6.sin6_scope_id;
         else if (asoc)
                 fl6->flowi6_oif = asoc->base.sk->sk_bound_dev_if;
+        if (t->flowlabel & SCTP_FLOWLABEL_SET_MASK)
+                fl6->flowlabel = htonl(t->flowlabel & SCTP_FLOWLABEL_VAL_MASK);
 
         pr_debug("%s: dst=%pI6 ", __func__, &fl6->daddr);
 
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 67f73d3a1356..e948db29ab53 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -426,13 +426,16 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
         struct dst_entry *dst = NULL;
         union sctp_addr *daddr = &t->ipaddr;
         union sctp_addr dst_saddr;
+        __u8 tos = inet_sk(sk)->tos;
 
+        if (t->dscp & SCTP_DSCP_SET_MASK)
+                tos = t->dscp & SCTP_DSCP_VAL_MASK;
         memset(fl4, 0x0, sizeof(struct flowi4));
         fl4->daddr  = daddr->v4.sin_addr.s_addr;
         fl4->fl4_dport = daddr->v4.sin_port;
         fl4->flowi4_proto = IPPROTO_SCTP;
         if (asoc) {
-                fl4->flowi4_tos = RT_CONN_FLAGS(asoc->base.sk);
+                fl4->flowi4_tos = RT_CONN_FLAGS_TOS(asoc->base.sk, tos);
                 fl4->flowi4_oif = asoc->base.sk->sk_bound_dev_if;
                 fl4->fl4_sport = htons(asoc->base.bind_addr.port);
         }
@@ -495,7 +498,7 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                 fl4->fl4_sport = laddr->a.v4.sin_port;
                 flowi4_update_output(fl4,
                                      asoc->base.sk->sk_bound_dev_if,
-                                     RT_CONN_FLAGS(asoc->base.sk),
+                                     RT_CONN_FLAGS_TOS(asoc->base.sk, tos),
                                      daddr->v4.sin_addr.s_addr,
                                      laddr->a.v4.sin_addr.s_addr);
 
@@ -971,16 +974,21 @@ static inline int sctp_v4_xmit(struct sk_buff *skb,
                                struct sctp_transport *transport)
 {
         struct inet_sock *inet = inet_sk(skb->sk);
+        __u8 dscp = inet->tos;
 
         pr_debug("%s: skb:%p, len:%d, src:%pI4, dst:%pI4\n", __func__, skb,
-                 skb->len, &transport->fl.u.ip4.saddr, &transport->fl.u.ip4.daddr);
+                 skb->len, &transport->fl.u.ip4.saddr,
+                 &transport->fl.u.ip4.daddr);
+
+        if (transport->dscp & SCTP_DSCP_SET_MASK)
+                dscp = transport->dscp & SCTP_DSCP_VAL_MASK;
 
         inet->pmtudisc = transport->param_flags & SPP_PMTUD_ENABLE ?
                          IP_PMTUDISC_DO : IP_PMTUDISC_DONT;
 
         SCTP_INC_STATS(sock_net(&inet->sk), SCTP_MIB_OUTSCTPPACKS);
 
-        return ip_queue_xmit(&inet->sk, skb, &transport->fl);
+        return __ip_queue_xmit(&inet->sk, skb, &transport->fl, dscp);
 }
 
 static struct sctp_af sctp_af_inet;