path: root/net/ipv4/sysctl_net_ipv4.c

// SPDX-License-Identifier: GPL-2.0
/*
 * sysctl_net_ipv4.c: sysctl interface to net IPV4 subsystem.
 *
 * Begun April 1, 1996, Mike Shaver.
 * Added /proc/sys/net/ipv4 directory entry (empty =) ). [MS]
 */

#include <linux/sysctl.h>
#include <linux/seqlock.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/ip_fib.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/cipso_ipv4.h>
#include <net/ping.h>
#include <net/protocol.h>
#include <net/netevent.h>

static int tcp_retr1_max = 255;
static int ip_local_port_range_min[] = { 1, 1 };
static int ip_local_port_range_max[] = { 65535, 65535 };
static int tcp_adv_win_scale_min = -31;
static int tcp_adv_win_scale_max = 31;
static int tcp_app_win_max = 31;
static int tcp_min_snd_mss_min = TCP_MIN_SND_MSS;
static int tcp_min_snd_mss_max = 65535;
static int ip_privileged_port_min;
static int ip_privileged_port_max = 65535;
static int ip_ttl_min = 1;
static int ip_ttl_max = 255;
static int tcp_syn_retries_min = 1;
static int tcp_syn_retries_max = MAX_TCP_SYNCNT;
static int tcp_syn_linear_timeouts_max = MAX_TCP_SYNCNT;
static unsigned long ip_ping_group_range_min[] = { 0, 0 };
static unsigned long ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX };
static u32 u32_max_div_HZ = UINT_MAX / HZ;
static int one_day_secs = 24 * 3600;
static u32 fib_multipath_hash_fields_all_mask __maybe_unused =
	FIB_MULTIPATH_HASH_FIELD_ALL_MASK;
static unsigned int tcp_child_ehash_entries_max = 16 * 1024 * 1024;
static unsigned int udp_child_hash_entries_max = UDP_HTABLE_SIZE_MAX;
static int tcp_plb_max_rounds = 31;
static int tcp_plb_max_cong_thresh = 256;

/* obsolete */
static int sysctl_tcp_low_latency __read_mostly;

/* Update system visible IP port range */
static void set_local_port_range(struct net *net, unsigned int low, unsigned int high)
{
	bool same_parity = !((low ^ high) & 1);

	if (same_parity && !net->ipv4.ip_local_ports.warned) {
		net->ipv4.ip_local_ports.warned = true;
		pr_err_ratelimited("ip_local_port_range: prefer different parity for start/end values.\n");
	}
	WRITE_ONCE(net->ipv4.ip_local_ports.range, high << 16 | low);
}

/* Validate changes from /proc interface. */
static int ipv4_local_port_range(const struct ctl_table *table, int write,
				 void *buffer, size_t *lenp, loff_t *ppos)
{
	struct net *net = table->data;
	int ret;
	int range[2];
	struct ctl_table tmp = {
		.data = &range,
		.maxlen = sizeof(range),
		.mode = table->mode,
		.extra1 = &ip_local_port_range_min,
		.extra2 = &ip_local_port_range_max,
	};

	inet_get_local_port_range(net, &range[0], &range[1]);

	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);

	if (write && ret == 0) {
		/* Ensure that the upper limit is not smaller than the lower,
		 * and that the lower does not encroach upon the privileged
		 * port limit.
		 */
		if ((range[1] < range[0]) ||
		    (range[0] < READ_ONCE(net->ipv4.sysctl_ip_prot_sock)))
			ret = -EINVAL;
		else
			set_local_port_range(net, range[0], range[1]);
	}

	return ret;