net/phonet/sysctl.c

   1 /*
   2  * File: sysctl.c
   3  *
   4  * Phonet /proc/sys/net/phonet interface implementation
   5  *
   6  * Copyright (C) 2008 Nokia Corporation.
   7  *
   8  * Author: Rémi Denis-Courmont
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * version 2 as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  22  * 02110-1301 USA
  23  */
  24
  25 #include <linux/seqlock.h>
  26 #include <linux/sysctl.h>
  27 #include <linux/errno.h>
  28 #include <linux/init.h>
  29
  30 #include <net/sock.h>
  31 #include <linux/phonet.h>
  32 #include <net/phonet/phonet.h>
  33
  34 #define DYNAMIC_PORT_MIN        0x40
  35 #define DYNAMIC_PORT_MAX        0x7f
  36
  37 static DEFINE_SEQLOCK(local_port_range_lock);
  38 static int local_port_range_min[2] = {0, 0};
  39 static int local_port_range_max[2] = {1023, 1023};
  40 static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
  41 static struct ctl_table_header *phonet_table_hrd;
  42
  43 static void set_local_port_range(int range[2])
  44 {
  45         write_seqlock(&local_port_range_lock);
  46         local_port_range[0] = range[0];
  47         local_port_range[1] = range[1];
  48         write_sequnlock(&local_port_range_lock);
  49 }
  50
  51 void phonet_get_local_port_range(int *min, int *max)
  52 {
  53         unsigned int seq;
  54
  55         do {
  56                 seq = read_seqbegin(&local_port_range_lock);
  57                 if (min)
  58                         *min = local_port_range[0];
  59                 if (max)
  60                         *max = local_port_range[1];
  61         } while (read_seqretry(&local_port_range_lock, seq));
  62 }
  63
  64 static int proc_local_port_range(ctl_table *table, int write,
  65                                 void __user *buffer,
  66                                 size_t *lenp, loff_t *ppos)
  67 {
  68         int ret;
  69         int range[2] = {local_port_range[0], local_port_range[1]};
  70         ctl_table tmp = {
  71                 .data = &range,
  72                 .maxlen = sizeof(range),
  73                 .mode = table->mode,
  74                 .extra1 = &local_port_range_min,
  75                 .extra2 = &local_port_range_max,
  76         };
  77
  78         ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
  79
  80         if (write && ret == 0) {
  81                 if (range[1] < range[0])
  82                         ret = -EINVAL;
  83                 else
  84                         set_local_port_range(range);
  85         }
  86
  87         return ret;
  88 }
  89
  90 static struct ctl_table phonet_table[] = {
  91         {
  92                 .procname       = "local_port_range",
  93                 .data           = &local_port_range,
  94                 .maxlen         = sizeof(local_port_range),
  95                 .mode           = 0644,
  96                 .proc_handler   = proc_local_port_range,
  97         },
  98         { }
  99 };
 100
 101 int __init phonet_sysctl_init(void)
 102 {
 103         phonet_table_hrd = register_net_sysctl(&init_net, "net/phonet", phonet_table);
 104         return phonet_table_hrd == NULL ? -ENOMEM : 0;
 105 }
 106
 107 void phonet_sysctl_exit(void)
 108 {
 109         unregister_net_sysctl_table(phonet_table_hrd);
 110 }