sysctl.c

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/*
 * File: sysctl.c
 *
 * Phonet /proc/sys/net/phonet interface implementation
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Author: Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#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(ctl_table *table, int write,
                void __user *buffer,
                size_t *lenp, loff_t *ppos)
{
    int ret;
    int range[2] = {local_port_range[0], local_port_range[1]};
    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);
}