1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * File: sysctl.c
4  *
5  * Phonet /proc/sys/net/phonet interface implementation
6  *
7  * Copyright (C) 2008 Nokia Corporation.
8  *
9  * Author: Rémi Denis-Courmont
10  */
11 
12 #include <linux/seqlock.h>
13 #include <linux/sysctl.h>
14 #include <linux/errno.h>
15 #include <linux/init.h>
16 
17 #include <net/sock.h>
18 #include <linux/phonet.h>
19 #include <net/phonet/phonet.h>
20 
21 #define DYNAMIC_PORT_MIN	0x40
22 #define DYNAMIC_PORT_MAX	0x7f
23 
24 static DEFINE_SEQLOCK(local_port_range_lock);
25 static int local_port_range_min[2] = {0, 0};
26 static int local_port_range_max[2] = {1023, 1023};
27 static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
28 static struct ctl_table_header *phonet_table_hrd;
29 
set_local_port_range(int range[2])30 static void set_local_port_range(int range[2])
31 {
32 	write_seqlock(&local_port_range_lock);
33 	local_port_range[0] = range[0];
34 	local_port_range[1] = range[1];
35 	write_sequnlock(&local_port_range_lock);
36 }
37 
phonet_get_local_port_range(int * min,int * max)38 void phonet_get_local_port_range(int *min, int *max)
39 {
40 	unsigned int seq;
41 
42 	do {
43 		seq = read_seqbegin(&local_port_range_lock);
44 		if (min)
45 			*min = local_port_range[0];
46 		if (max)
47 			*max = local_port_range[1];
48 	} while (read_seqretry(&local_port_range_lock, seq));
49 }
50 
proc_local_port_range(struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)51 static int proc_local_port_range(struct ctl_table *table, int write,
52 				 void *buffer, size_t *lenp, loff_t *ppos)
53 {
54 	int ret;
55 	int range[2] = {local_port_range[0], local_port_range[1]};
56 	struct ctl_table tmp = {
57 		.data = &range,
58 		.maxlen = sizeof(range),
59 		.mode = table->mode,
60 		.extra1 = &local_port_range_min,
61 		.extra2 = &local_port_range_max,
62 	};
63 
64 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
65 
66 	if (write && ret == 0) {
67 		if (range[1] < range[0])
68 			ret = -EINVAL;
69 		else
70 			set_local_port_range(range);
71 	}
72 
73 	return ret;
74 }
75 
76 static struct ctl_table phonet_table[] = {
77 	{
78 		.procname	= "local_port_range",
79 		.data		= &local_port_range,
80 		.maxlen		= sizeof(local_port_range),
81 		.mode		= 0644,
82 		.proc_handler	= proc_local_port_range,
83 	},
84 	{ }
85 };
86 
phonet_sysctl_init(void)87 int __init phonet_sysctl_init(void)
88 {
89 	phonet_table_hrd = register_net_sysctl(&init_net, "net/phonet", phonet_table);
90 	return phonet_table_hrd == NULL ? -ENOMEM : 0;
91 }
92 
phonet_sysctl_exit(void)93 void phonet_sysctl_exit(void)
94 {
95 	unregister_net_sysctl_table(phonet_table_hrd);
96 }
97