datagram.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * File: datagram.c
 *
 * Datagram (ISI) Phonet sockets
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
 *          Rémi Denis-Courmont
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <asm/ioctls.h>
#include <net/sock.h>

#include <linux/phonet.h>
#include <linux/export.h>
#include <net/phonet/phonet.h>

static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb);

/* associated socket ceases to exist */
static void pn_sock_close(struct sock *sk, long timeout)
{
	sk_common_release(sk);
}

static int pn_ioctl(struct sock *sk, int cmd, int *karg)
{
	struct sk_buff *skb;

	switch (cmd) {
	case SIOCINQ:
		spin_lock_bh(&sk->sk_receive_queue.lock);
		skb = skb_peek(&sk->sk_receive_queue);
		*karg = skb ? skb->len : 0;
		spin_unlock_bh(&sk->sk_receive_queue.lock);
		return 0;

	case SIOCPNADDRESOURCE:
	case SIOCPNDELRESOURCE: {
			u32 res = *karg;
			if (res >= 256)
				return -EINVAL;
			if (cmd == SIOCPNADDRESOURCE)
				return pn_sock_bind_res(sk, res);
			else
				return pn_sock_unbind_res(sk, res);
		}
	}

	return -ENOIOCTLCMD;
}

/* Destroy socket. All references are gone. */
static void pn_destruct(struct sock *sk)
{
	skb_queue_purge(&sk->sk_receive_queue);
}

static int pn_init(struct sock *sk)
{
	sk->sk_destruct = pn_destruct;
	return 0;
}

static int pn_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
	DECLARE_SOCKADDR(struct sockaddr_pn *, target, msg->msg_name);
	struct sk_buff *skb;
	int err;

	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|
				MSG_CMSG_COMPAT))
		return -EOPNOTSUPP;

	if (target == NULL)
		return -EDESTADDRREQ;

	if (msg->msg_namelen < sizeof(struct sockaddr_pn))
		return -EINVAL;

	if (target->spn_family != AF_PHONET)
		return -EAFNOSUPPORT;

	skb = sock_alloc_send_skb(sk, MAX_PHONET_HEADER + len,
					msg->msg_flags & MSG_DONTWAIT, &err);
	if (skb == NULL)
		return err;
	skb_reserve(skb, MAX_PHONET_HEADER);

	err = memcpy_from_msg((void *)skb_put(skb, len), msg, len);
	if (err < 0) {
		kfree_skb(skb);
		return err;
	}

	/*
	 * Fill in the Phonet header and
	 * finally pass the packet forwards.
	 */
	err = pn_skb_send(sk, skb, target);

	/* If ok, return len. */
	return (err >= 0) ? len : err;
}

static int pn_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
		      int flags, int *addr_len)
{
	struct sk_buff *skb = NULL;
	struct sockaddr_pn sa;
	int rval = -EOPNOTSUPP;
	int copylen;

	if (flags & ~(MSG_PEEK|MSG_TRUNC|MSG_DONTWAIT|MSG_NOSIGNAL|
			MSG_CMSG_COMPAT))
		goto out_nofree;

	skb = skb_recv_datagram(sk, flags, &rval);
	if (skb == NULL)
		goto out_nofree;

	pn_skb_get_src_sockaddr(skb, &sa);

	copylen = skb->len;
	if (len < copylen) {
		msg->msg_flags |= MSG_TRUNC;
		copylen = len;
	}

	rval = skb_copy_datagram_msg(skb, 0, msg, copylen);
	if (rval) {
		rval = -EFAULT;
		goto out;
	}

	rval = (flags & MSG_TRUNC) ? skb->len : copylen;

	if (msg->msg_name != NULL) {
		__sockaddr_check_size(sizeof(sa));
		memcpy(msg->msg_name, &sa, sizeof(sa));
		*addr_len = sizeof(sa);
	}

out:
	skb_free_datagram(sk, skb);

out_nofree:
	return rval;
}

/* Queue an skb for a sock. */
static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
	int err = sock_queue_rcv_skb(sk, skb);

	if (err < 0)
		kfree_skb(skb);
	return err ? NET_RX_DROP : NET_RX_SUCCESS;
}

/* Module registration */
static struct proto pn_proto = {
	.close		= pn_sock_close,
	.ioctl		= pn_ioctl,
	.init		= pn_init,
	.sendmsg	= pn_sendmsg,
	.recvmsg	= pn_recvmsg,
	.backlog_rcv	= pn_backlog_rcv,
	.hash		= pn_sock_hash,
	.unhash		= pn_sock_unhash,
	.get_port	= pn_sock_get_port,
	.obj_size	= sizeof(struct pn_sock),
	.owner		= THIS_MODULE,
	.name		= "PHONET",
};

static const struct phonet_protocol pn_dgram_proto = {
	.ops		= &phonet_dgram_ops,
	.prot		= &pn_proto,
	.sock_type	= SOCK_DGRAM,
};

int __init isi_register(void)
{
	return phonet_proto_register(PN_PROTO_PHONET, &pn_dgram_proto);
}

void __exit isi_unregister(void)
{
	phonet_proto_unregister(PN_PROTO_PHONET, &pn_dgram_proto);
}