Merge branch 'sctp-add-support-for-sk_reuseport'

Xin Long says:

====================
sctp: add support for sk_reuseport

sctp sk_reuseport allows multiple socks to listen on the same port and
addresses, as long as these socks have the same uid. This works pretty
much as TCP/UDP does, the only difference is that sctp is multi-homing
and all the bind_addrs in these socks will have to completely matched,
otherwise listen() will return err.

The below is when 5 sockets are listening on 172.16.254.254:6400 on a
server, 26 sockets on a client connect to 172.16.254.254:6400 and each
may be processed by a different socket on the server which is selected
by hash(lport, pport, paddr) in reuseport_select_sock():

 # ss --sctp -nn
   State      Recv-Q Send-Q        Local Address:Port     Peer Address:Port
   LISTEN     0      10           172.16.254.254:6400                *:*
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.2.1:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.2.4:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.3.3:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.3.4:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.5.2:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.5.3:1234
   LISTEN     0      10           172.16.254.254:6400                *:*
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.1.3:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.1.4:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.3.2:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.4.1:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.4.2:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.4.3:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.4.4:1234
   LISTEN     0      10           172.16.254.254:6400                *:*
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.1.2:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.3.5:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.4.5:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400   172.16.253.253:1234
   LISTEN     0      10           172.16.254.254:6400                *:*
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.2.2:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.2.3:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.5.4:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.5.5:1234
   LISTEN     0      10           172.16.254.254:6400                *:*
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.1.1:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.1.5:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.2.5:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.3.1:1234
   `- ESTAB   0      0       172.16.254.254%eth1:6400       172.16.5.1:1234
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -152,7 +152,7 @@ int sctp_primitive_RECONF(struct net *net, struct sctp_association *asoc,
  */
 int sctp_rcv(struct sk_buff *skb);
 int sctp_v4_err(struct sk_buff *skb, u32 info);
-void sctp_hash_endpoint(struct sctp_endpoint *);
+int sctp_hash_endpoint(struct sctp_endpoint *ep);
 void sctp_unhash_endpoint(struct sctp_endpoint *);
 struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *,
 			     struct sctphdr *, struct sctp_association **,

include/net/sctp/structs.h

@@ -96,7 +96,9 @@ struct sctp_stream;
 
 struct sctp_bind_bucket {
 	unsigned short	port;
-	unsigned short	fastreuse;
+	signed char	fastreuse;
+	signed char	fastreuseport;
+	kuid_t		fastuid;
 	struct hlist_node	node;
 	struct hlist_head	owner;
 	struct net	*net;
@@ -1190,6 +1192,8 @@ int sctp_bind_addr_conflict(struct sctp_bind_addr *, const union sctp_addr *,
 			 struct sctp_sock *, struct sctp_sock *);
 int sctp_bind_addr_state(const struct sctp_bind_addr *bp,
 			 const union sctp_addr *addr);
+int sctp_bind_addrs_check(struct sctp_sock *sp,
+			  struct sctp_sock *sp2, int cnt2);
 union sctp_addr *sctp_find_unmatch_addr(struct sctp_bind_addr	*bp,
 					const union sctp_addr	*addrs,
 					int			addrcnt,

net/core/sock_reuseport.c

@@ -187,6 +187,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany)
 		call_rcu(&old_reuse->rcu, reuseport_free_rcu);
 	return 0;
 }
+EXPORT_SYMBOL(reuseport_add_sock);
 
 void reuseport_detach_sock(struct sock *sk)
 {

net/sctp/bind_addr.c

@@ -337,6 +337,34 @@ int sctp_bind_addr_match(struct sctp_bind_addr *bp,
 	return match;
 }
 
+int sctp_bind_addrs_check(struct sctp_sock *sp,
+			  struct sctp_sock *sp2, int cnt2)
+{
+	struct sctp_bind_addr *bp2 = &sp2->ep->base.bind_addr;
+	struct sctp_bind_addr *bp = &sp->ep->base.bind_addr;
+	struct sctp_sockaddr_entry *laddr, *laddr2;
+	bool exist = false;
+	int cnt = 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(laddr, &bp->address_list, list) {
+		list_for_each_entry_rcu(laddr2, &bp2->address_list, list) {
+			if (sp->pf->af->cmp_addr(&laddr->a, &laddr2->a) &&
+			    laddr->valid && laddr2->valid) {
+				exist = true;
+				goto next;
+			}
+		}
+		cnt = 0;
+		break;
+next:
+		cnt++;
+	}
+	rcu_read_unlock();
+
+	return (cnt == cnt2) ? 0 : (exist ? -EEXIST : 1);
+}
+
 /* Does the address 'addr' conflict with any addresses in
  * the bp.
  */

net/sctp/input.c

@@ -57,6 +57,7 @@
 #include <net/sctp/checksum.h>
 #include <net/net_namespace.h>
 #include <linux/rhashtable.h>
+#include <net/sock_reuseport.h>
 
 /* Forward declarations for internal helpers. */
 static int sctp_rcv_ootb(struct sk_buff *);
@@ -65,8 +66,10 @@ static struct sctp_association *__sctp_rcv_lookup(struct net *net,
 				      const union sctp_addr *paddr,
 				      const union sctp_addr *laddr,
 				      struct sctp_transport **transportp);
-static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
-						const union sctp_addr *laddr);
+static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
+					struct net *net, struct sk_buff *skb,
+					const union sctp_addr *laddr,
+					const union sctp_addr *daddr);
 static struct sctp_association *__sctp_lookup_association(
 					struct net *net,
 					const union sctp_addr *local,
@@ -171,7 +174,7 @@ int sctp_rcv(struct sk_buff *skb)
 	asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
 
 	if (!asoc)
-		ep = __sctp_rcv_lookup_endpoint(net, &dest);
+		ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src);
 
 	/* Retrieve the common input handling substructure. */
 	rcvr = asoc ? &asoc->base : &ep->base;
@@ -721,43 +724,87 @@ static int sctp_rcv_ootb(struct sk_buff *skb)
 }
 
 /* Insert endpoint into the hash table.  */
-static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
+static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
 {
-	struct net *net = sock_net(ep->base.sk);
-	struct sctp_ep_common *epb;
+	struct sock *sk = ep->base.sk;
+	struct net *net = sock_net(sk);
 	struct sctp_hashbucket *head;
+	struct sctp_ep_common *epb;
 
 	epb = &ep->base;
-
 	epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
 	head = &sctp_ep_hashtable[epb->hashent];
 
+	if (sk->sk_reuseport) {
+		bool any = sctp_is_ep_boundall(sk);
+		struct sctp_ep_common *epb2;
+		struct list_head *list;
+		int cnt = 0, err = 1;
+
+		list_for_each(list, &ep->base.bind_addr.address_list)
+			cnt++;
+
+		sctp_for_each_hentry(epb2, &head->chain) {
+			struct sock *sk2 = epb2->sk;
+
+			if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
+			    !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
+			    !sk2->sk_reuseport)
+				continue;
+
+			err = sctp_bind_addrs_check(sctp_sk(sk2),
+						    sctp_sk(sk), cnt);
+			if (!err) {
+				err = reuseport_add_sock(sk, sk2, any);
+				if (err)
+					return err;
+				break;
+			} else if (err < 0) {
+				return err;
+			}
+		}
+
+		if (err) {
+			err = reuseport_alloc(sk, any);
+			if (err)
+				return err;
+		}
+	}
+
 	write_lock(&head->lock);
 	hlist_add_head(&epb->node, &head->chain);
 	write_unlock(&head->lock);
+	return 0;
 }
 
 /* Add an endpoint to the hash. Local BH-safe. */
-void sctp_hash_endpoint(struct sctp_endpoint *ep)
+int sctp_hash_endpoint(struct sctp_endpoint *ep)
 {
+	int err;
+
 	local_bh_disable();
-	__sctp_hash_endpoint(ep);
+	err = __sctp_hash_endpoint(ep);
 	local_bh_enable();
+
+	return err;
 }
 
 /* Remove endpoint from the hash table.  */
 static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
 {
-	struct net *net = sock_net(ep->base.sk);
+	struct sock *sk = ep->base.sk;
 	struct sctp_hashbucket *head;
 	struct sctp_ep_common *epb;
 
 	epb = &ep->base;
 
-	epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port);
+	epb->hashent = sctp_ep_hashfn(sock_net(sk), epb->bind_addr.port);
 
 	head = &sctp_ep_hashtable[epb->hashent];
 
+	if (rcu_access_pointer(sk->sk_reuseport_cb))
+		reuseport_detach_sock(sk);
+
 	write_lock(&head->lock);
 	hlist_del_init(&epb->node);
 	write_unlock(&head->lock);
@@ -771,16 +818,35 @@ void sctp_unhash_endpoint(struct sctp_endpoint *ep)
 	local_bh_enable();
 }
 
+static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
+				const union sctp_addr *paddr, __u32 seed)
+{
+	__u32 addr;
+
+	if (paddr->sa.sa_family == AF_INET6)
+		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
+	else
+		addr = (__force __u32)paddr->v4.sin_addr.s_addr;
+
+	return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
+			     (__force __u32)lport, net_hash_mix(net), seed);
+}
+
 /* Look up an endpoint. */
-static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
-						const union sctp_addr *laddr)
+static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
+					struct net *net, struct sk_buff *skb,
+					const union sctp_addr *laddr,
+					const union sctp_addr *paddr)
 {
 	struct sctp_hashbucket *head;
 	struct sctp_ep_common *epb;
 	struct sctp_endpoint *ep;
+	struct sock *sk;
+	__be16 lport;
 	int hash;
 
-	hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port));
+	lport = laddr->v4.sin_port;
+	hash = sctp_ep_hashfn(net, ntohs(lport));
 	head = &sctp_ep_hashtable[hash];
 	read_lock(&head->lock);
 	sctp_for_each_hentry(epb, &head->chain) {
@@ -792,6 +858,15 @@ static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
 	ep = sctp_sk(net->sctp.ctl_sock)->ep;
 
 hit:
+	sk = ep->base.sk;
+	if (sk->sk_reuseport) {
+		__u32 phash = sctp_hashfn(net, lport, paddr, 0);
+
+		sk = reuseport_select_sock(sk, phash, skb,
+					   sizeof(struct sctphdr));
+		if (sk)
+			ep = sctp_sk(sk)->ep;
+	}
 	sctp_endpoint_hold(ep);
 	read_unlock(&head->lock);
 	return ep;
@@ -830,35 +905,17 @@ static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
 static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
 {
 	const struct sctp_transport *t = data;
-	const union sctp_addr *paddr = &t->ipaddr;
-	const struct net *net = sock_net(t->asoc->base.sk);
-	__be16 lport = htons(t->asoc->base.bind_addr.port);
-	__u32 addr;
-
-	if (paddr->sa.sa_family == AF_INET6)
-		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
-	else
-		addr = (__force __u32)paddr->v4.sin_addr.s_addr;
 
-	return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
-			     (__force __u32)lport, net_hash_mix(net), seed);
+	return sctp_hashfn(sock_net(t->asoc->base.sk),
+			   htons(t->asoc->base.bind_addr.port),
+			   &t->ipaddr, seed);
 }
 
 static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
 {
 	const struct sctp_hash_cmp_arg *x = data;
-	const union sctp_addr *paddr = x->paddr;
-	const struct net *net = x->net;
-	__be16 lport = x->lport;
-	__u32 addr;
-
-	if (paddr->sa.sa_family == AF_INET6)
-		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
-	else
-		addr = (__force __u32)paddr->v4.sin_addr.s_addr;
 
-	return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
-			     (__force __u32)lport, net_hash_mix(net), seed);
+	return sctp_hashfn(x->net, x->lport, x->paddr, seed);
 }
 
 static const struct rhashtable_params sctp_hash_params = {

net/sctp/socket.c

@@ -7644,8 +7644,10 @@ static struct sctp_bind_bucket *sctp_bucket_create(
 
 static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 {
-	bool reuse = (sk->sk_reuse || sctp_sk(sk)->reuse);
+	struct sctp_sock *sp = sctp_sk(sk);
+	bool reuse = (sk->sk_reuse || sp->reuse);
 	struct sctp_bind_hashbucket *head; /* hash list */
+	kuid_t uid = sock_i_uid(sk);
 	struct sctp_bind_bucket *pp;
 	unsigned short snum;
 	int ret;
@@ -7721,7 +7723,10 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 
 		pr_debug("%s: found a possible match\n", __func__);
 
-		if (pp->fastreuse && reuse && sk->sk_state != SCTP_SS_LISTENING)
+		if ((pp->fastreuse && reuse &&
+		     sk->sk_state != SCTP_SS_LISTENING) ||
+		    (pp->fastreuseport && sk->sk_reuseport &&
+		     uid_eq(pp->fastuid, uid)))
 			goto success;
 
 		/* Run through the list of sockets bound to the port
@@ -7735,16 +7740,18 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 		 * in an endpoint.
 		 */
 		sk_for_each_bound(sk2, &pp->owner) {
-			struct sctp_endpoint *ep2;
-			ep2 = sctp_sk(sk2)->ep;
+			struct sctp_sock *sp2 = sctp_sk(sk2);
+			struct sctp_endpoint *ep2 = sp2->ep;
 
 			if (sk == sk2 ||
-			    (reuse && (sk2->sk_reuse || sctp_sk(sk2)->reuse) &&
-			     sk2->sk_state != SCTP_SS_LISTENING))
+			    (reuse && (sk2->sk_reuse || sp2->reuse) &&
+			     sk2->sk_state != SCTP_SS_LISTENING) ||
+			    (sk->sk_reuseport && sk2->sk_reuseport &&
+			     uid_eq(uid, sock_i_uid(sk2))))
 				continue;
 
-			if (sctp_bind_addr_conflict(&ep2->base.bind_addr, addr,
-						 sctp_sk(sk2), sctp_sk(sk))) {
+			if (sctp_bind_addr_conflict(&ep2->base.bind_addr,
+						    addr, sp2, sp)) {
 				ret = (long)sk2;
 				goto fail_unlock;
 			}
@@ -7767,19 +7774,32 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 			pp->fastreuse = 1;
 		else
 			pp->fastreuse = 0;
-	} else if (pp->fastreuse &&
+
+		if (sk->sk_reuseport) {
+			pp->fastreuseport = 1;
+			pp->fastuid = uid;
+		} else {
+			pp->fastreuseport = 0;
+		}
+	} else {
+		if (pp->fastreuse &&
 		    (!reuse || sk->sk_state == SCTP_SS_LISTENING))
 			pp->fastreuse = 0;
 
+		if (pp->fastreuseport &&
+		    (!sk->sk_reuseport || !uid_eq(pp->fastuid, uid)))
+			pp->fastreuseport = 0;
+	}
+
 	/* We are set, so fill up all the data in the hash table
 	 * entry, tie the socket list information with the rest of the
 	 * sockets FIXME: Blurry, NPI (ipg).
 	 */
 success:
-	if (!sctp_sk(sk)->bind_hash) {
+	if (!sp->bind_hash) {
 		inet_sk(sk)->inet_num = snum;
 		sk_add_bind_node(sk, &pp->owner);
-		sctp_sk(sk)->bind_hash = pp;
+		sp->bind_hash = pp;
 	}
 	ret = 0;
 
@@ -7852,8 +7872,7 @@ static int sctp_listen_start(struct sock *sk, int backlog)
 	}
 
 	sk->sk_max_ack_backlog = backlog;
-	sctp_hash_endpoint(ep);
-	return 0;
+	return sctp_hash_endpoint(ep);
 }
 
 /*