// SPDX-License-Identifier: GPL-2.0-only /* * File: pep-gprs.c * * GPRS over Phonet pipe end point socket * * Copyright (C) 2008 Nokia Corporation. * * Author: RĂ©mi Denis-Courmont */ #include <linux/kernel.h> #include <linux/netdevice.h> #include <linux/if_ether.h> #include <linux/if_arp.h> #include <net/sock.h> #include <linux/if_phonet.h> #include <net/tcp_states.h> #include <net/phonet/gprs.h> #define GPRS_DEFAULT_MTU 1400 struct gprs_dev { struct sock *sk; void (*old_state_change)(struct sock *); void (*old_data_ready)(struct sock *); void (*old_write_space)(struct sock *); struct net_device *dev; }; static __be16 gprs_type_trans(struct sk_buff *skb) { const u8 *pvfc; u8 buf; pvfc = skb_header_pointer(skb, 0, 1, &buf); if (!pvfc) return htons(0); /* Look at IP version field */ switch (*pvfc >> 4) { case 4: return htons(ETH_P_IP); case 6: return htons(ETH_P_IPV6); } return htons(0); } static void gprs_writeable(struct gprs_dev *gp) { struct net_device *dev = gp->dev; if (pep_writeable(gp->sk)) netif_wake_queue(dev); } /* * Socket callbacks */ static void gprs_state_change(struct sock *sk) { struct gprs_dev *gp = sk->sk_user_data; if (sk->sk_state == TCP_CLOSE_WAIT) { struct net_device *dev = gp->dev; netif_stop_queue(dev); netif_carrier_off(dev); } } static int gprs_recv(struct gprs_dev *gp, struct sk_buff *skb) { struct net_device *dev = gp->dev; int err = 0; __be16 protocol = gprs_type_trans(skb); if (!protocol) { err = -EINVAL; goto drop; } if (skb_headroom(skb) & 3) { struct sk_buff *rskb, *fs; int flen = 0; /* Phonet Pipe data header may be misaligned (3 bytes), * so wrap the IP packet as a single fragment of an head-less * socket buffer. The network stack will pull what it needs, * but at least, the whole IP payload is not memcpy'd. */ rskb = netdev_alloc_skb(dev, 0); if (!rskb) { err = -ENOBUFS; goto drop; } skb_shinfo(rskb)->frag_list = skb; rskb->len += skb->len; rskb->data_len += rskb->len; rskb->truesize += rskb->len; /* Avoid nested fragments */ skb_walk_frags(skb, fs) flen += fs->len; skb->next = skb_shinfo(skb)->frag_list; skb_frag_list_init(skb); skb->len -= flen; skb->data_len -= flen; skb->truesize -= flen; skb = rskb; } skb->protocol = protocol; skb_reset_mac_header(skb); skb->dev = dev; if (likely(dev->flags & IFF_UP)) { dev->stats.rx_packets++; dev->stats.rx_bytes += skb->len; netif_rx(skb); skb = NULL; } else err = -ENODEV; drop: if (skb) { dev_kfree_skb(skb); dev->stats.rx_dropped++; } return err; } static void gprs_data_ready(struct sock *sk) { struct gprs_dev *gp = sk->sk_user_data; struct sk_buff *skb; while ((skb = pep_read(sk)) != NULL) { skb_orphan(skb); gprs_recv(gp, skb); } } static void gprs_write_space(struct sock *sk) { struct gprs_dev *gp = sk->sk_user_data; if (netif_running(gp->dev)) gprs_writeable(gp); } /* * Network device callbacks */ static int gprs_open(struct net_device *dev) { struct gprs_dev *gp = netdev_priv(dev); gprs_writeable(gp); return 0; } static int gprs_close(struct net_device *dev) { netif_stop_queue(dev); return 0; } static netdev_tx_t gprs_xmit(struct sk_buff *skb, struct net_device *dev) { struct gprs_dev *gp = netdev_priv(dev); struct sock *sk = gp->sk; int len, err; switch (skb->protocol) { case htons(ETH_P_IP): case htons(ETH_P_IPV6): break; default: dev_kfree_skb(skb); return NETDEV_TX_OK; } skb_orphan(skb); skb_set_owner_w(skb, sk); len = skb->len; err = pep_write(sk, skb); if (err) { net_dbg_ratelimited("%s: TX error (%d)\n", dev->name, err); dev->stats.tx_aborted_errors++; dev->stats.tx_errors++; } else { dev->stats.tx_packets++; dev->stats.tx_bytes += len; } netif_stop_queue(dev); if (pep_writeable(sk)) netif_wake_queue(dev); return NETDEV_TX_OK; } static const struct net_device_ops gprs_netdev_ops = { .ndo_open = gprs_open, .ndo_stop = gprs_close, .ndo_start_xmit = gprs_xmit, }; static void gprs_setup(struct net_device *dev) { dev->features = NETIF_F_FRAGLIST; dev->type = ARPHRD_PHONET_PIPE; dev->flags = IFF_POINTOPOINT | IFF_NOARP; dev->mtu = GPRS_DEFAULT_MTU; dev->min_mtu = 576; dev->max_mtu = (PHONET_MAX_MTU - 11); dev->hard_header_len = 0; dev->addr_len = 0; dev->tx_queue_len = 10; dev->netdev_ops = &gprs_netdev_ops; dev->needs_free_netdev = true; } /* * External interface */ /* * Attach a GPRS interface to a datagram socket. * Returns the interface index on success, negative error code on error. */ int gprs_attach(struct sock *sk) { static const char ifname[] = "gprs%d"; struct gprs_dev *gp; struct net_device *dev; int err; if (unlikely(sk->sk_type == SOCK_STREAM)) return -EINVAL; /* need packet boundaries */ /* Create net device */ dev = alloc_netdev(sizeof(*gp), ifname, NET_NAME_UNKNOWN, gprs_setup); if (!dev) return -ENOMEM; gp = netdev_priv(dev); gp->sk = sk; gp->dev = dev; netif_stop_queue(dev); err = register_netdev(dev); if (err) { free_netdev(dev); return err; } lock_sock(sk); if (unlikely(sk->sk_user_data)) { err = -EBUSY; goto out_rel; } if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) || sock_flag(sk, SOCK_DEAD))) { err = -EINVAL; goto out_rel; } sk->sk_user_data = gp; gp->old_state_change = sk->sk_state_change; gp->old_data_ready = sk->sk_data_ready; gp->old_write_space = sk->sk_write_space; sk->sk_state_change = gprs_state_change; sk->sk_data_ready = gprs_data_ready; sk->sk_write_space = gprs_write_space; release_sock(sk); sock_hold(sk); printk(KERN_DEBUG"%s: attached\n", dev->name); return dev->ifindex; out_rel: release_sock(sk); unregister_netdev(dev); return err; } void gprs_detach(struct sock *sk) { struct gprs_dev *gp = sk->sk_user_data; struct net_device *dev = gp->dev; lock_sock(sk); sk->sk_user_data = NULL; sk->sk_state_change = gp->old_state_change; sk->sk_data_ready = gp->old_data_ready; sk->sk_write_space = gp->old_write_space; release_sock(sk); printk(KERN_DEBUG"%s: detached\n", dev->name); unregister_netdev(dev); sock_put(sk); }