1 files changed, 455 insertions, 0 deletions

diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c
new file mode 100644
index 000000000..7ed8ab724
--- /dev/null
+++ b/net/ax25/ax25_in.c
@@ -0,0 +1,455 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
+ * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
+ * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <asm/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+
+/*
+ *	Given a fragment, queue it on the fragment queue and if the fragment
+ *	is complete, send it back to ax25_rx_iframe.
+ */
+static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
+{
+	struct sk_buff *skbn, *skbo;
+
+	if (ax25->fragno != 0) {
+		if (!(*skb->data & AX25_SEG_FIRST)) {
+			if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
+				/* Enqueue fragment */
+				ax25->fragno = *skb->data & AX25_SEG_REM;
+				skb_pull(skb, 1);	/* skip fragno */
+				ax25->fraglen += skb->len;
+				skb_queue_tail(&ax25->frag_queue, skb);
+
+				/* Last fragment received ? */
+				if (ax25->fragno == 0) {
+					skbn = alloc_skb(AX25_MAX_HEADER_LEN +
+							 ax25->fraglen,
+							 GFP_ATOMIC);
+					if (!skbn) {
+						skb_queue_purge(&ax25->frag_queue);
+						return 1;
+					}
+
+					skb_reserve(skbn, AX25_MAX_HEADER_LEN);
+
+					skbn->dev   = ax25->ax25_dev->dev;
+					skb_reset_network_header(skbn);
+					skb_reset_transport_header(skbn);
+
+					/* Copy data from the fragments */
+					while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
+						skb_copy_from_linear_data(skbo,
+							  skb_put(skbn, skbo->len),
+									  skbo->len);
+						kfree_skb(skbo);
+					}
+
+					ax25->fraglen = 0;
+
+					if (ax25_rx_iframe(ax25, skbn) == 0)
+						kfree_skb(skbn);
+				}
+
+				return 1;
+			}
+		}
+	} else {
+		/* First fragment received */
+		if (*skb->data & AX25_SEG_FIRST) {
+			skb_queue_purge(&ax25->frag_queue);
+			ax25->fragno = *skb->data & AX25_SEG_REM;
+			skb_pull(skb, 1);		/* skip fragno */
+			ax25->fraglen = skb->len;
+			skb_queue_tail(&ax25->frag_queue, skb);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ *	This is where all valid I frames are sent to, to be dispatched to
+ *	whichever protocol requires them.
+ */
+int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
+{
+	int (*func)(struct sk_buff *, ax25_cb *);
+	unsigned char pid;
+	int queued = 0;
+
+	if (skb == NULL) return 0;
+
+	ax25_start_idletimer(ax25);
+
+	pid = *skb->data;
+
+	if (pid == AX25_P_IP) {
+		/* working around a TCP bug to keep additional listeners
+		 * happy. TCP re-uses the buffer and destroys the original
+		 * content.
+		 */
+		struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
+		if (skbn != NULL) {
+			kfree_skb(skb);
+			skb = skbn;
+		}
+
+		skb_pull(skb, 1);	/* Remove PID */
+		skb->mac_header = skb->network_header;
+		skb_reset_network_header(skb);
+		skb->dev      = ax25->ax25_dev->dev;
+		skb->pkt_type = PACKET_HOST;
+		skb->protocol = htons(ETH_P_IP);
+		netif_rx(skb);
+		return 1;
+	}
+	if (pid == AX25_P_SEGMENT) {
+		skb_pull(skb, 1);	/* Remove PID */
+		return ax25_rx_fragment(ax25, skb);
+	}
+
+	if ((func = ax25_protocol_function(pid)) != NULL) {
+		skb_pull(skb, 1);	/* Remove PID */
+		return (*func)(skb, ax25);
+	}
+
+	if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
+		if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
+		    ax25->pidincl) {
+			if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
+				queued = 1;
+			else
+				ax25->condition |= AX25_COND_OWN_RX_BUSY;
+		}
+	}
+
+	return queued;
+}
+
+/*
+ *	Higher level upcall for a LAPB frame
+ */
+static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
+{
+	int queued = 0;
+
+	if (ax25->state == AX25_STATE_0)
+		return 0;
+
+	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
+	case AX25_PROTO_STD_SIMPLEX:
+	case AX25_PROTO_STD_DUPLEX:
+		queued = ax25_std_frame_in(ax25, skb, type);
+		break;
+
+#ifdef CONFIG_AX25_DAMA_SLAVE
+	case AX25_PROTO_DAMA_SLAVE:
+		if (dama || ax25->ax25_dev->dama.slave)
+			queued = ax25_ds_frame_in(ax25, skb, type);
+		else
+			queued = ax25_std_frame_in(ax25, skb, type);
+		break;
+#endif
+	}
+
+	return queued;
+}
+
+static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
+	ax25_address *dev_addr, struct packet_type *ptype)
+{
+	ax25_address src, dest, *next_digi = NULL;
+	int type = 0, mine = 0, dama;
+	struct sock *make, *sk;
+	ax25_digi dp, reverse_dp;
+	ax25_cb *ax25;
+	ax25_dev *ax25_dev;
+
+	/*
+	 *	Process the AX.25/LAPB frame.
+	 */
+
+	skb_reset_transport_header(skb);
+
+	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
+		goto free;
+
+	/*
+	 *	Parse the address header.
+	 */
+
+	if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
+		goto free;
+
+	/*
+	 *	Ours perhaps ?
+	 */
+	if (dp.lastrepeat + 1 < dp.ndigi)		/* Not yet digipeated completely */
+		next_digi = &dp.calls[dp.lastrepeat + 1];
+
+	/*
+	 *	Pull of the AX.25 headers leaving the CTRL/PID bytes
+	 */
+	skb_pull(skb, ax25_addr_size(&dp));
+
+	/* For our port addresses ? */
+	if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
+		mine = 1;
+
+	/* Also match on any registered callsign from L3/4 */
+	if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
+		mine = 1;
+
+	/* UI frame - bypass LAPB processing */
+	if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
+		skb_set_transport_header(skb, 2); /* skip control and pid */
+
+		ax25_send_to_raw(&dest, skb, skb->data[1]);
+
+		if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
+			goto free;
+
+		/* Now we are pointing at the pid byte */
+		switch (skb->data[1]) {
+		case AX25_P_IP:
+			skb_pull(skb,2);		/* drop PID/CTRL */
+			skb_reset_transport_header(skb);
+			skb_reset_network_header(skb);
+			skb->dev      = dev;
+			skb->pkt_type = PACKET_HOST;
+			skb->protocol = htons(ETH_P_IP);
+			netif_rx(skb);
+			break;
+
+		case AX25_P_ARP:
+			skb_pull(skb,2);
+			skb_reset_transport_header(skb);
+			skb_reset_network_header(skb);
+			skb->dev      = dev;
+			skb->pkt_type = PACKET_HOST;
+			skb->protocol = htons(ETH_P_ARP);
+			netif_rx(skb);
+			break;
+		case AX25_P_TEXT:
+			/* Now find a suitable dgram socket */
+			sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
+			if (sk != NULL) {
+				bh_lock_sock(sk);
+				if (atomic_read(&sk->sk_rmem_alloc) >=
+				    sk->sk_rcvbuf) {
+					kfree_skb(skb);
+				} else {
+					/*
+					 *	Remove the control and PID.
+					 */
+					skb_pull(skb, 2);
+					if (sock_queue_rcv_skb(sk, skb) != 0)
+						kfree_skb(skb);
+				}
+				bh_unlock_sock(sk);
+				sock_put(sk);
+			} else {
+				kfree_skb(skb);
+			}
+			break;
+
+		default:
+			kfree_skb(skb);	/* Will scan SOCK_AX25 RAW sockets */
+			break;
+		}
+
+		return 0;
+	}
+
+	/*
+	 *	Is connected mode supported on this device ?
+	 *	If not, should we DM the incoming frame (except DMs) or
+	 *	silently ignore them. For now we stay quiet.
+	 */
+	if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
+		goto free;
+
+	/* LAPB */
+
+	/* AX.25 state 1-4 */
+
+	ax25_digi_invert(&dp, &reverse_dp);
+
+	if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
+		/*
+		 *	Process the frame. If it is queued up internally it
+		 *	returns one otherwise we free it immediately. This
+		 *	routine itself wakes the user context layers so we do
+		 *	no further work
+		 */
+		if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
+			kfree_skb(skb);
+
+		ax25_cb_put(ax25);
+		return 0;
+	}
+
+	/* AX.25 state 0 (disconnected) */
+
+	/* a) received not a SABM(E) */
+
+	if ((*skb->data & ~AX25_PF) != AX25_SABM &&
+	    (*skb->data & ~AX25_PF) != AX25_SABME) {
+		/*
+		 *	Never reply to a DM. Also ignore any connects for
+		 *	addresses that are not our interfaces and not a socket.
+		 */
+		if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
+			ax25_return_dm(dev, &src, &dest, &dp);
+
+		goto free;
+	}
+
+	/* b) received SABM(E) */
+
+	if (dp.lastrepeat + 1 == dp.ndigi)
+		sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
+	else
+		sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
+
+	if (sk != NULL) {
+		bh_lock_sock(sk);
+		if (sk_acceptq_is_full(sk) ||
+		    (make = ax25_make_new(sk, ax25_dev)) == NULL) {
+			if (mine)
+				ax25_return_dm(dev, &src, &dest, &dp);
+			kfree_skb(skb);
+			bh_unlock_sock(sk);
+			sock_put(sk);
+
+			return 0;
+		}
+
+		ax25 = ax25_sk(make);
+		skb_set_owner_r(skb, make);
+		skb_queue_head(&sk->sk_receive_queue, skb);
+
+		make->sk_state = TCP_ESTABLISHED;
+
+		sk->sk_ack_backlog++;
+		bh_unlock_sock(sk);
+	} else {
+		if (!mine)
+			goto free;
+
+		if ((ax25 = ax25_create_cb()) == NULL) {
+			ax25_return_dm(dev, &src, &dest, &dp);
+			goto free;
+		}
+
+		ax25_fillin_cb(ax25, ax25_dev);
+	}
+
+	ax25->source_addr = dest;
+	ax25->dest_addr   = src;
+
+	/*
+	 *	Sort out any digipeated paths.
+	 */
+	if (dp.ndigi && !ax25->digipeat &&
+	    (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
+		kfree_skb(skb);
+		ax25_destroy_socket(ax25);
+		if (sk)
+			sock_put(sk);
+		return 0;
+	}
+
+	if (dp.ndigi == 0) {
+		kfree(ax25->digipeat);
+		ax25->digipeat = NULL;
+	} else {
+		/* Reverse the source SABM's path */
+		memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
+	}
+
+	if ((*skb->data & ~AX25_PF) == AX25_SABME) {
+		ax25->modulus = AX25_EMODULUS;
+		ax25->window  = ax25_dev->values[AX25_VALUES_EWINDOW];
+	} else {
+		ax25->modulus = AX25_MODULUS;
+		ax25->window  = ax25_dev->values[AX25_VALUES_WINDOW];
+	}
+
+	ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
+
+#ifdef CONFIG_AX25_DAMA_SLAVE
+	if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
+		ax25_dama_on(ax25);
+#endif
+
+	ax25->state = AX25_STATE_3;
+
+	ax25_cb_add(ax25);
+
+	ax25_start_heartbeat(ax25);
+	ax25_start_t3timer(ax25);
+	ax25_start_idletimer(ax25);
+
+	if (sk) {
+		if (!sock_flag(sk, SOCK_DEAD))
+			sk->sk_data_ready(sk);
+		sock_put(sk);
+	} else {
+free:
+		kfree_skb(skb);
+	}
+	return 0;
+}
+
+/*
+ *	Receive an AX.25 frame via a SLIP interface.
+ */
+int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
+		  struct packet_type *ptype, struct net_device *orig_dev)
+{
+	skb_orphan(skb);
+
+	if (!net_eq(dev_net(dev), &init_net)) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	if ((*skb->data & 0x0F) != 0) {
+		kfree_skb(skb);	/* Not a KISS data frame */
+		return 0;
+	}
+
+	skb_pull(skb, AX25_KISS_HEADER_LEN);	/* Remove the KISS byte */
+
+	return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
+}