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   1 /*
   2  * File: sysctl.c
   3  *
   4  * Phonet /proc/sys/net/phonet interface implementation
   5  *
   6  * Copyright (C) 2008 Nokia Corporation.
   7  *
   8  * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
   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 #define DYNAMIC_PORT_MIN        0x40
  31 #define DYNAMIC_PORT_MAX        0x7f
  32
  33 static DEFINE_SEQLOCK(local_port_range_lock);
  34 static int local_port_range_min[2] = {0, 0};
  35 static int local_port_range_max[2] = {1023, 1023};
  36 static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
  37 static struct ctl_table_header *phonet_table_hrd;
  38
  39 static void set_local_port_range(int range[2])
  40 {
  41         write_seqlock(&local_port_range_lock);
  42         local_port_range[0] = range[0];
  43         local_port_range[1] = range[1];
  44         write_sequnlock(&local_port_range_lock);
  45 }
  46
  47 void phonet_get_local_port_range(int *min, int *max)
  48 {
  49         unsigned seq;
  50         do {
  51                 seq = read_seqbegin(&local_port_range_lock);
  52                 if (min)
  53                         *min = local_port_range[0];
  54                 if (max)
  55                         *max = local_port_range[1];
  56         } while (read_seqretry(&local_port_range_lock, seq));
  57 }
  58
  59 static int proc_local_port_range(ctl_table *table, int write, struct file *filp,
  60                                 void __user *buffer,
  61                                 size_t *lenp, loff_t *ppos)
  62 {
  63         int ret;
  64         int range[2] = {local_port_range[0], local_port_range[1]};
  65         ctl_table tmp = {
  66                 .data = &range,
  67                 .maxlen = sizeof(range),
  68                 .mode = table->mode,
  69                 .extra1 = &local_port_range_min,
  70                 .extra2 = &local_port_range_max,
  71         };
  72
  73         ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);
  74
  75         if (write && ret == 0) {
  76                 if (range[1] < range[0])
  77                         ret = -EINVAL;
  78                 else
  79                         set_local_port_range(range);
  80         }
  81
  82         return ret;
  83 }
  84
  85 static struct ctl_table phonet_table[] = {
  86         {
  87                 .ctl_name       = CTL_UNNUMBERED,
  88                 .procname       = "local_port_range",
  89                 .data           = &local_port_range,
  90                 .maxlen         = sizeof(local_port_range),
  91                 .mode           = 0644,
  92                 .proc_handler   = proc_local_port_range,
  93                 .strategy       = NULL,
  94         },
  95         { .ctl_name = 0 }
  96 };
  97
  98 static struct ctl_path phonet_ctl_path[] = {
  99         { .procname = "net", .ctl_name = CTL_NET, },
 100         { .procname = "phonet", .ctl_name = CTL_UNNUMBERED, },
 101         { },
 102 };
 103
 104 int __init phonet_sysctl_init(void)
 105 {
 106         phonet_table_hrd = register_sysctl_paths(phonet_ctl_path, phonet_table);
 107         return phonet_table_hrd == NULL ? -ENOMEM : 0;
 108 }
 109
 110 void phonet_sysctl_exit(void)
 111 {
 112         unregister_sysctl_table(phonet_table_hrd);
 113 }