path: root/net/ipv4/inet_connection_sock.c

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Support for INET connection oriented protocols.
 *
 * Authors:	See the TCP sources
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or(at your option) any later version.
 */

#include <linux/module.h>
#include <linux/jhash.h>

#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#include <net/inet_timewait_sock.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/tcp_states.h>
#include <net/xfrm.h>

#ifdef INET_CSK_DEBUG
const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
EXPORT_SYMBOL(inet_csk_timer_bug_msg);
#endif

/*
 * This struct holds the first and last local port number.
 */
struct local_ports sysctl_local_ports __read_mostly = {
	.lock = __SEQLOCK_UNLOCKED(sysctl_local_ports.lock),
	.range = { 32768, 61000 },
};

unsigned long *sysctl_local_reserved_ports;
EXPORT_SYMBOL(sysctl_local_reserved_ports);

void inet_get_local_port_range(int *low, int *high)
{
	unsigned int seq;

	do {
		seq = read_seqbegin(&sysctl_local_ports.lock);

		*low = sysctl_local_ports.range[0];
		*high = sysctl_local_ports.range[1];
	} while (read_seqretry(&sysctl_local_ports.lock, seq));
}
EXPORT_SYMBOL(inet_get_local_port_range);

int inet_csk_bind_conflict(const struct sock *sk,
			   const struct inet_bind_bucket *tb, bool relax)
{
	struct sock *sk2;
	int reuse = sk->sk_reuse;
	int reuseport = sk->sk_reuseport;
	kuid_t uid = sock_i_uid((struct sock *)sk);

	/*
	 * Unlike other sk lookup places we do not check
	 * for sk_net here, since _all_ the socks listed
	 * in tb->owners list belong to the same net - the
	 * one this bucket belongs to.
	 */

	sk_for_each_bound(sk2, &tb->owners) {
		if (sk != sk2 &&
		    !inet_v6_ipv6only(sk2) &&
		    (!sk->sk_bound_dev_if ||
		     !sk2->sk_bound_dev_if ||
		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
			if ((!reuse || !sk2->sk_reuse ||
			    sk2->sk_state == TCP_LISTEN) &&
			    (!reuseport || !sk2->sk_reuseport ||
			    (sk2->sk_state != TCP_TIME_WAIT &&
			     !uid_eq(uid, sock_i_uid(sk2))))) {
				const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
				if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
				    sk2_rcv_saddr == sk_rcv_saddr(sk))
					break;
			}
			if (!relax && reuse && sk2->sk_reuse &&
			    sk2->sk_state != TCP_LISTEN) {
				const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);

				if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
				    sk2_rcv_saddr == sk_rcv_saddr(sk))
					break;
			}
		}
	}
	return sk2 != NULL;
}
EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);

/* Obtain a reference to a local port for the given sock,
 * if snum is zero it means select any available local port.
 */
int inet_csk_get_port(struct sock *sk, unsigned short snum)
{
	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
	struct inet_bind_hashbucket *head;
	struct inet_bind_bucket *tb;
	int ret, attempts = 5;
	struct net *net = sock_net(sk);
	int smallest_size = -1, smallest_rover;
	kuid_t uid = sock_i_uid(sk);

	local_bh_disable();
	if (!snum) {
		int remaining, rover, low, high;

again:
		inet_get_local_port_range(&low, &high);
		remaining = (high - low) + 1;
		smallest_rover = rover = net_random() % remaining + low;

		smallest_size = -1;
		do {
			if (inet_is_reserved_local_port(rover))
				goto next_nolock;
			head = &hashinfo->bhash[inet_bhashfn(net, rover,
					hashinfo->bhash_size)];
			spin_lock(&head->lock);
			inet_bind_bucket_for_each(tb, &head->chain)
				if (net_eq(ib_net(tb), net) && tb->port == rover) {
					if (((tb->fastreuse > 0 &&
					      sk->sk_reuse &&
					      sk->sk_state != TCP_LISTEN) ||
					     (tb->fastreuseport > 0 &&
					      sk->sk_reuseport &&
					      uid_eq(tb->fastuid, uid))) &&
					    (tb->num_owners < smallest_size || smallest_size == -1)) {
						smallest_size =