452 lines
10 KiB
C
452 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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*
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* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
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* Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
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*/
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/slab.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <linux/uaccess.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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/*
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* Given a fragment, queue it on the fragment queue and if the fragment
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* is complete, send it back to ax25_rx_iframe.
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*/
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static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
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{
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struct sk_buff *skbn, *skbo;
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if (ax25->fragno != 0) {
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if (!(*skb->data & AX25_SEG_FIRST)) {
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if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
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/* Enqueue fragment */
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ax25->fragno = *skb->data & AX25_SEG_REM;
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skb_pull(skb, 1); /* skip fragno */
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ax25->fraglen += skb->len;
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skb_queue_tail(&ax25->frag_queue, skb);
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/* Last fragment received ? */
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if (ax25->fragno == 0) {
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skbn = alloc_skb(AX25_MAX_HEADER_LEN +
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ax25->fraglen,
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GFP_ATOMIC);
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if (!skbn) {
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skb_queue_purge(&ax25->frag_queue);
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return 1;
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}
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skb_reserve(skbn, AX25_MAX_HEADER_LEN);
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skbn->dev = ax25->ax25_dev->dev;
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skb_reset_network_header(skbn);
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skb_reset_transport_header(skbn);
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/* Copy data from the fragments */
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while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
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skb_copy_from_linear_data(skbo,
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skb_put(skbn, skbo->len),
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skbo->len);
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kfree_skb(skbo);
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}
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ax25->fraglen = 0;
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if (ax25_rx_iframe(ax25, skbn) == 0)
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kfree_skb(skbn);
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}
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return 1;
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}
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}
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} else {
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/* First fragment received */
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if (*skb->data & AX25_SEG_FIRST) {
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skb_queue_purge(&ax25->frag_queue);
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ax25->fragno = *skb->data & AX25_SEG_REM;
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skb_pull(skb, 1); /* skip fragno */
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ax25->fraglen = skb->len;
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skb_queue_tail(&ax25->frag_queue, skb);
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return 1;
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}
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}
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return 0;
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}
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/*
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* This is where all valid I frames are sent to, to be dispatched to
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* whichever protocol requires them.
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*/
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int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
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{
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int (*func)(struct sk_buff *, ax25_cb *);
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unsigned char pid;
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int queued = 0;
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if (skb == NULL) return 0;
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ax25_start_idletimer(ax25);
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pid = *skb->data;
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if (pid == AX25_P_IP) {
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/* working around a TCP bug to keep additional listeners
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* happy. TCP re-uses the buffer and destroys the original
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* content.
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*/
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struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
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if (skbn != NULL) {
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kfree_skb(skb);
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skb = skbn;
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}
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skb_pull(skb, 1); /* Remove PID */
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skb->mac_header = skb->network_header;
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skb_reset_network_header(skb);
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skb->dev = ax25->ax25_dev->dev;
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skb->pkt_type = PACKET_HOST;
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skb->protocol = htons(ETH_P_IP);
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netif_rx(skb);
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return 1;
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}
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if (pid == AX25_P_SEGMENT) {
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skb_pull(skb, 1); /* Remove PID */
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return ax25_rx_fragment(ax25, skb);
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}
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if ((func = ax25_protocol_function(pid)) != NULL) {
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skb_pull(skb, 1); /* Remove PID */
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return (*func)(skb, ax25);
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}
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if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
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if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
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ax25->pidincl) {
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if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
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queued = 1;
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else
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ax25->condition |= AX25_COND_OWN_RX_BUSY;
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}
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}
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return queued;
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}
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/*
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* Higher level upcall for a LAPB frame
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*/
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static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
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{
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int queued = 0;
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if (ax25->state == AX25_STATE_0)
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return 0;
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switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
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case AX25_PROTO_STD_SIMPLEX:
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case AX25_PROTO_STD_DUPLEX:
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queued = ax25_std_frame_in(ax25, skb, type);
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break;
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#ifdef CONFIG_AX25_DAMA_SLAVE
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case AX25_PROTO_DAMA_SLAVE:
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if (dama || ax25->ax25_dev->dama.slave)
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queued = ax25_ds_frame_in(ax25, skb, type);
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else
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queued = ax25_std_frame_in(ax25, skb, type);
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break;
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#endif
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}
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return queued;
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}
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static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
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const ax25_address *dev_addr, struct packet_type *ptype)
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{
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ax25_address src, dest, *next_digi = NULL;
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int type = 0, mine = 0, dama;
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struct sock *make, *sk;
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ax25_digi dp, reverse_dp;
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ax25_cb *ax25;
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ax25_dev *ax25_dev;
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/*
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* Process the AX.25/LAPB frame.
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*/
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skb_reset_transport_header(skb);
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if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
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goto free;
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/*
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* Parse the address header.
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*/
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if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
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goto free;
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/*
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* Ours perhaps ?
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*/
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if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */
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next_digi = &dp.calls[dp.lastrepeat + 1];
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/*
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* Pull of the AX.25 headers leaving the CTRL/PID bytes
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*/
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skb_pull(skb, ax25_addr_size(&dp));
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/* For our port addresses ? */
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if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
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mine = 1;
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/* Also match on any registered callsign from L3/4 */
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if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
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mine = 1;
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/* UI frame - bypass LAPB processing */
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if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
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skb_set_transport_header(skb, 2); /* skip control and pid */
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ax25_send_to_raw(&dest, skb, skb->data[1]);
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if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
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goto free;
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/* Now we are pointing at the pid byte */
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switch (skb->data[1]) {
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case AX25_P_IP:
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skb_pull(skb,2); /* drop PID/CTRL */
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skb_reset_transport_header(skb);
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skb_reset_network_header(skb);
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skb->dev = dev;
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skb->pkt_type = PACKET_HOST;
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skb->protocol = htons(ETH_P_IP);
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netif_rx(skb);
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break;
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case AX25_P_ARP:
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skb_pull(skb,2);
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skb_reset_transport_header(skb);
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skb_reset_network_header(skb);
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skb->dev = dev;
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skb->pkt_type = PACKET_HOST;
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skb->protocol = htons(ETH_P_ARP);
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netif_rx(skb);
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break;
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case AX25_P_TEXT:
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/* Now find a suitable dgram socket */
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sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
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if (sk != NULL) {
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bh_lock_sock(sk);
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if (atomic_read(&sk->sk_rmem_alloc) >=
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sk->sk_rcvbuf) {
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kfree_skb(skb);
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} else {
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/*
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* Remove the control and PID.
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*/
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skb_pull(skb, 2);
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if (sock_queue_rcv_skb(sk, skb) != 0)
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kfree_skb(skb);
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}
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bh_unlock_sock(sk);
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sock_put(sk);
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} else {
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kfree_skb(skb);
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}
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break;
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default:
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kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
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break;
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}
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return 0;
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}
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/*
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* Is connected mode supported on this device ?
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* If not, should we DM the incoming frame (except DMs) or
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* silently ignore them. For now we stay quiet.
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*/
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if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
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goto free;
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/* LAPB */
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/* AX.25 state 1-4 */
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ax25_digi_invert(&dp, &reverse_dp);
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if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
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/*
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* Process the frame. If it is queued up internally it
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* returns one otherwise we free it immediately. This
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* routine itself wakes the user context layers so we do
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* no further work
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*/
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if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
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kfree_skb(skb);
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ax25_cb_put(ax25);
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return 0;
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}
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/* AX.25 state 0 (disconnected) */
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/* a) received not a SABM(E) */
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if ((*skb->data & ~AX25_PF) != AX25_SABM &&
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(*skb->data & ~AX25_PF) != AX25_SABME) {
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/*
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* Never reply to a DM. Also ignore any connects for
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* addresses that are not our interfaces and not a socket.
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*/
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if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
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ax25_return_dm(dev, &src, &dest, &dp);
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goto free;
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}
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/* b) received SABM(E) */
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if (dp.lastrepeat + 1 == dp.ndigi)
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sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
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else
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sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
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if (sk != NULL) {
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bh_lock_sock(sk);
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if (sk_acceptq_is_full(sk) ||
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(make = ax25_make_new(sk, ax25_dev)) == NULL) {
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if (mine)
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ax25_return_dm(dev, &src, &dest, &dp);
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kfree_skb(skb);
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bh_unlock_sock(sk);
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sock_put(sk);
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return 0;
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}
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ax25 = sk_to_ax25(make);
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skb_set_owner_r(skb, make);
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skb_queue_head(&sk->sk_receive_queue, skb);
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make->sk_state = TCP_ESTABLISHED;
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sk_acceptq_added(sk);
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bh_unlock_sock(sk);
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} else {
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if (!mine)
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goto free;
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if ((ax25 = ax25_create_cb()) == NULL) {
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ax25_return_dm(dev, &src, &dest, &dp);
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goto free;
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}
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ax25_fillin_cb(ax25, ax25_dev);
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}
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ax25->source_addr = dest;
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ax25->dest_addr = src;
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/*
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* Sort out any digipeated paths.
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*/
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if (dp.ndigi && !ax25->digipeat &&
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(ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
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kfree_skb(skb);
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ax25_destroy_socket(ax25);
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if (sk)
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sock_put(sk);
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return 0;
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}
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if (dp.ndigi == 0) {
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kfree(ax25->digipeat);
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ax25->digipeat = NULL;
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} else {
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/* Reverse the source SABM's path */
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memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
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}
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if ((*skb->data & ~AX25_PF) == AX25_SABME) {
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ax25->modulus = AX25_EMODULUS;
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ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW];
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} else {
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ax25->modulus = AX25_MODULUS;
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ax25->window = ax25_dev->values[AX25_VALUES_WINDOW];
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}
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ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
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#ifdef CONFIG_AX25_DAMA_SLAVE
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if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
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ax25_dama_on(ax25);
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#endif
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ax25->state = AX25_STATE_3;
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ax25_cb_add(ax25);
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ax25_start_heartbeat(ax25);
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ax25_start_t3timer(ax25);
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ax25_start_idletimer(ax25);
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if (sk) {
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if (!sock_flag(sk, SOCK_DEAD))
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sk->sk_data_ready(sk);
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sock_put(sk);
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} else {
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free:
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kfree_skb(skb);
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}
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return 0;
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}
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/*
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* Receive an AX.25 frame via a SLIP interface.
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*/
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int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *ptype, struct net_device *orig_dev)
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{
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skb_orphan(skb);
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if (!net_eq(dev_net(dev), &init_net)) {
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kfree_skb(skb);
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return 0;
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}
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if ((*skb->data & 0x0F) != 0) {
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kfree_skb(skb); /* Not a KISS data frame */
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return 0;
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}
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skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */
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return ax25_rcv(skb, dev, (const ax25_address *)dev->dev_addr, ptype);
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}
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