linux/drivers/connector/connector.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	connector.c
 *
 * 2004+ Copyright (c) Evgeniy Polyakov <[email protected]>
 * All rights reserved.
 */

#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <linux/moduleparam.h>
#include <linux/connector.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>

#include <net/sock.h>

MODULE_LICENSE(…) …;
MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_ALIAS_NET_PF_PROTO(…);

static struct cn_dev cdev;

static int cn_already_initialized;

/*
 * Sends mult (multiple) cn_msg at a time.
 *
 * msg->seq and msg->ack are used to determine message genealogy.
 * When someone sends message it puts there locally unique sequence
 * and random acknowledge numbers.  Sequence number may be copied into
 * nlmsghdr->nlmsg_seq too.
 *
 * Sequence number is incremented with each message to be sent.
 *
 * If we expect a reply to our message then the sequence number in
 * received message MUST be the same as in original message, and
 * acknowledge number MUST be the same + 1.
 *
 * If we receive a message and its sequence number is not equal to the
 * one we are expecting then it is a new message.
 *
 * If we receive a message and its sequence number is the same as one
 * we are expecting but it's acknowledgement number is not equal to
 * the acknowledgement number in the original message + 1, then it is
 * a new message.
 *
 * If msg->len != len, then additional cn_msg messages are expected following
 * the first msg.
 *
 * The message is sent to, the portid if given, the group if given, both if
 * both, or if both are zero then the group is looked up and sent there.
 */
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
			 gfp_t gfp_mask, netlink_filter_fn filter,
			 void *filter_data)
{ … }
EXPORT_SYMBOL_GPL(…);

/* same as cn_netlink_send_mult except msg->len is used for len */
int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
	gfp_t gfp_mask)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Callback helper - queues work and setup destructor for given data.
 */
static int cn_call_callback(struct sk_buff *skb)
{ … }

/*
 * Allow non-root access for NETLINK_CONNECTOR family having CN_IDX_PROC
 * multicast group.
 */
static int cn_bind(struct net *net, int group)
{ … }

static void cn_release(struct sock *sk, unsigned long *groups)
{ … }

/*
 * Main netlink receiving function.
 *
 * It checks skb, netlink header and msg sizes, and calls callback helper.
 */
static void cn_rx_skb(struct sk_buff *skb)
{ … }

/*
 * Callback add routing - adds callback with given ID and name.
 * If there is registered callback with the same ID it will not be added.
 *
 * May sleep.
 */
int cn_add_callback(const struct cb_id *id, const char *name,
		    void (*callback)(struct cn_msg *,
				     struct netlink_skb_parms *))
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Callback remove routing - removes callback
 * with given ID.
 * If there is no registered callback with given
 * ID nothing happens.
 *
 * May sleep while waiting for reference counter to become zero.
 */
void cn_del_callback(const struct cb_id *id)
{ … }
EXPORT_SYMBOL_GPL(…);

static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
{ … }

static int cn_init(void)
{ … }

static void cn_fini(void)
{ … }

subsys_initcall(cn_init);
module_exit(cn_fini);