Phonet: proc interface for port range

Phonet endpoints are bound to individual ports.
This provides a /proc/sys/net/phonet (or sysctl) interface for
selecting the range of automatically allocated ports (much like the
ip_local_port_range with IPv4).

Signed-off-by: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 113 insertions, 0 deletions

diff --git a/net/phonet/sysctl.c b/net/phonet/sysctl.c
new file mode 100644
index 000000000000..600a4309b8c8
--- /dev/null
+++ b/net/phonet/sysctl.c
@@ -0,0 +1,113 @@
+/*
+ * File: sysctl.c
+ *
+ * Phonet /proc/sys/net/phonet interface implementation
+ *
+ * Copyright (C) 2008 Nokia Corporation.
+ *
+ * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
+ *
+ * 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>
+
+#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 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, struct file *filp,
+                                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, filp, 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[] = {
+        {
+                .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "local_port_range",
+                .data           = &local_port_range,
+                .maxlen         = sizeof(local_port_range),
+                .mode           = 0644,
+                .proc_handler   = &proc_local_port_range,
+                .strategy       = NULL,
+        },
+        { .ctl_name = 0 }
+};
+
+struct ctl_path phonet_ctl_path[] = {
+        { .procname = "net", .ctl_name = CTL_NET, },
+        { .procname = "phonet", .ctl_name = CTL_UNNUMBERED, },
+        { },
+};
+
+int __init phonet_sysctl_init(void)
+{
+        phonet_table_hrd = register_sysctl_paths(phonet_ctl_path, phonet_table);
+        return phonet_table_hrd == NULL ? -ENOMEM : 0;
+}
+
+void phonet_sysctl_exit(void)
+{
+        unregister_sysctl_table(phonet_table_hrd);
+}