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Commit f24d43c0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

udp: complete port availability checking 



While looking at UDP port randomization, I noticed it
was litle bit pessimistic, not looking at type of sockets
(IPV6/IPV4) and not looking at bound addresses if any.

We should perform same tests than when binding to a
specific port.

This permits a cleanup of udp_lib_get_port()

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 626e264d

net/ipv4/udp.c

+19 −24
Original line number Original line Diff line number Diff line
@@ -122,14 +122,23 @@ EXPORT_SYMBOL(sysctl_udp_wmem_min); 
atomic_t udp_memory_allocated;

atomic_t udp_memory_allocated;

EXPORT_SYMBOL(udp_memory_allocated);

EXPORT_SYMBOL(udp_memory_allocated);





static inline int __udp_lib_lport_inuse(struct net *net, __u16 num,

static int udp_lib_lport_inuse(struct net *net, __u16 num,

					const struct hlist_head udptable[])

			       const struct hlist_head udptable[],

			       struct sock *sk,

			       int (*saddr_comp)(const struct sock *sk1,

						 const struct sock *sk2))

{

{

	struct sock *sk;

	struct sock *sk2;

	struct hlist_node *node;

	struct hlist_node *node;





	sk_for_each(sk, node, &udptable[udp_hashfn(net, num)])

	sk_for_each(sk2, node, &udptable[udp_hashfn(net, num)])

		if (net_eq(sock_net(sk), net) && sk->sk_hash == num)

		if (net_eq(sock_net(sk2), net)			&&

		    sk2 != sk					&&

		    sk2->sk_hash == num				&&

		    (!sk2->sk_reuse || !sk->sk_reuse)		&&

		    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if

			|| sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&

		    (*saddr_comp)(sk, sk2))

			return 1;

			return 1;

	return 0;

	return 0;

}

}
@@ -146,9 +155,6 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, 
					 const struct sock *sk2 )    )

					 const struct sock *sk2 )    )

{

{

	struct hlist_head *udptable = sk->sk_prot->h.udp_hash;

	struct hlist_head *udptable = sk->sk_prot->h.udp_hash;

	struct hlist_node *node;

	struct hlist_head *head;

	struct sock *sk2;

	int    error = 1;

	int    error = 1;

	struct net *net = sock_net(sk);

	struct net *net = sock_net(sk);
@@ -165,32 +171,21 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, 
		rand = net_random();

		rand = net_random();

		snum = first = rand % remaining + low;

		snum = first = rand % remaining + low;

		rand |= 1;

		rand |= 1;

		while (__udp_lib_lport_inuse(net, snum, udptable)) {

		while (udp_lib_lport_inuse(net, snum, udptable, sk,

					   saddr_comp)) {

			do {

			do {

				snum = snum + rand;

				snum = snum + rand;

			} while (snum < low || snum > high);

			} while (snum < low || snum > high);

			if (snum == first)

			if (snum == first)

				goto fail;

				goto fail;

		}

		}

	} else {

	} else if (udp_lib_lport_inuse(net, snum, udptable, sk, saddr_comp))

		head = &udptable[udp_hashfn(net, snum)];



		sk_for_each(sk2, node, head)

			if (sk2->sk_hash == snum                             &&

			    sk2 != sk                                        &&

			    net_eq(sock_net(sk2), net)			     &&

			    (!sk2->sk_reuse        || !sk->sk_reuse)         &&

			    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if

			     || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&

			    (*saddr_comp)(sk, sk2)                             )

		goto fail;

		goto fail;

	}





	inet_sk(sk)->num = snum;

	inet_sk(sk)->num = snum;

	sk->sk_hash = snum;

	sk->sk_hash = snum;

	if (sk_unhashed(sk)) {

	if (sk_unhashed(sk)) {

		head = &udptable[udp_hashfn(net, snum)];

		sk_add_node(sk, &udptable[udp_hashfn(net, snum)]);

		sk_add_node(sk, head);

		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

	}

	}

	error = 0;

	error = 0;