// SPDX-License-Identifier: GPL-2.0-only
/*
 * File: sysctl.c
 *
 * Phonet /proc/sys/net/phonet interface implementation
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Author: Rémi Denis-Courmont
 */

#include <linux/seqlock.h>
#include <linux/sysctl.h>
#include <linux/errno.h>
#include <linux/init.h>

#include <net/sock.h>
#include <linux/phonet.h>
#include <net/phonet/phonet.h>

#define DYNAMIC_PORT_MIN        0x40
#define DYNAMIC_PORT_MAX        0x7f

static DEFINE_SEQLOCK(local_port_range_lock);
static int local_port_range_min[2] = {0, 0};
static int local_port_range_max[2] = {1023, 1023};
static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
static struct ctl_table_header *phonet_table_hrd;

static void set_local_port_range(int range[2])
{
        write_seqlock(&local_port_range_lock);
        local_port_range[0] = range[0];
        local_port_range[1] = range[1];
        write_sequnlock(&local_port_range_lock);
}

void phonet_get_local_port_range(int *min, int *max)
{
        unsigned int seq;

        do {
                seq = read_seqbegin(&local_port_range_lock);
                if (min)
                        *min = local_port_range[0];
                if (max)
                        *max = local_port_range[1];
        } while (read_seqretry(&local_port_range_lock, seq));
}

static int proc_local_port_range(const struct ctl_table *table, int write,
                                 void *buffer, size_t *lenp, loff_t *ppos)
{
        int ret;
        int range[2] = {local_port_range[0], local_port_range[1]};
        struct ctl_table tmp = {
                .data = &range,
                .maxlen = sizeof(range),
                .mode = table->mode,
                .extra1 = &local_port_range_min,
                .extra2 = &local_port_range_max,
        };

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

        if (write && ret == 0) {
                if (range[1] < range[0])
                        ret = -EINVAL;
                else
                        set_local_port_range(range);
        }

        return ret;
}

static struct ctl_table phonet_table[] = {
        {
                .procname       = "local_port_range",
                .data           = &local_port_range,
                .maxlen         = sizeof(local_port_range),
                .mode           = 0644,
                .proc_handler   = proc_local_port_range,
        },
};

int __init phonet_sysctl_init(void)
{
        phonet_table_hrd = register_net_sysctl(&init_net, "net/phonet", phonet_table);
        return phonet_table_hrd == NULL ? -ENOMEM : 0;
}

void phonet_sysctl_exit(void)
{
        unregister_net_sysctl_table(phonet_table_hrd);
}