dn_nsp_in.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Network Services Protocol (Input)
 *
 * Author:      Eduardo Marcelo Serrat <[e-mail]>
 *
 * Changes:
 *
 *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
 *                       original dn_nsp.c.
 *    Steve Whitehouse:  Updated to work with my new routing architecture.
 *    Steve Whitehouse:  Add changes from Eduardo Serrat's patches.
 *    Steve Whitehouse:  Put all ack handling code in a common routine.
 *    Steve Whitehouse:  Put other common bits into dn_nsp_rx()
 *    Steve Whitehouse:  More checks on skb->len to catch bogus packets
 *                       Fixed various race conditions and possible nasties.
 *    Steve Whitehouse:  Now handles returned conninit frames.
 *     David S. Miller:  New socket locking
 *    Steve Whitehouse:  Fixed lockup when socket filtering was enabled.
 *         Paul Koning:  Fix to push CC sockets into RUN when acks are
 *                       received.
 *    Steve Whitehouse:
 *   Patrick Caulfield:  Checking conninits for correctness & sending of error
 *                       responses.
 */

/******************************************************************************
    (c) 1995-1998 E.M. Serrat		[e-mail]
    
    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
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
*******************************************************************************/

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/inet.h>
#include <linux/route.h>
#include <net/sock.h>
#include <asm/segment.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/termios.h>      
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/netfilter_decnet.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/dn_nsp.h>
#include <net/dn_dev.h>
#include <net/dn_route.h>

extern int decnet_log_martians;

static void dn_log_martian(struct sk_buff *skb, const char *msg)
{
	if (decnet_log_martians && net_ratelimit()) {
		char *devname = skb->dev ? skb->dev->name : "???";
		struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
		printk(KERN_INFO "DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n", msg, devname, cb->src, cb->dst, cb->src_port, cb->dst_port);
	}
}

/*
 * For this function we've flipped the cross-subchannel bit
 * if the message is an otherdata or linkservice message. Thus
 * we can use it to work out what to update.
 */
static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
{
	struct dn_scp *scp = &sk->protinfo.dn;
	unsigned short type = ((ack >> 12) & 0x0003);
	int wakeup = 0;

	switch(type) {
		case 0: /* ACK - Data */
			if (after(ack, scp->ackrcv_dat)) {
				scp->ackrcv_dat = ack & 0x0fff;
				wakeup |= dn_nsp_check_xmit_queue(sk, skb, &scp->data_xmit_queue, ack);
			}
			break;
		case 1: /* NAK - Data */
			break;
		case 2: /* ACK - OtherData */
			if (after(ack, scp->ackrcv_oth)) {
				scp->ackrcv_oth = ack & 0x0fff;
				wakeup |= dn_nsp_check_xmit_queue(sk, skb, &scp->other_xmit_queue, ack);
			}
			break;
		case 3: /* NAK - OtherData */
			break;
	}

	if (wakeup && !sk->dead)
		sk->state_change(sk);
}

/*
 * This function is a universal ack processor.
 */
static int dn_process_ack(struct sock *sk, struct sk_buff *skb, int oth)
{
	unsigned short *ptr = (unsigned short *)skb->data;
	int len = 0;
	unsigned short ack;

	if (skb->len < 2)
		return len;

	if ((ack = dn_ntohs(*ptr)) & 0x8000) {
		skb_pull(skb, 2);
		ptr++;
		len += 2;
		if ((ack & 0x4000) == 0) {
			if (oth) 
				ack ^= 0x2000;
			dn_ack(sk, skb, ack);
		}
	}

	if (skb->len < 2)
		return len;

	if ((ack = dn_ntohs(*ptr)) & 0x8000) {
		skb_pull(skb, 2);
		len += 2;
		if ((ack & 0x4000) == 0) {
			if (oth) 
				ack ^= 0x2000;
			dn_ack(sk, skb, ack);
		}
	}

	return len;
}


/**
 * dn_check_idf - Check an image data field format is correct.
 * @pptr: Pointer to pointer to image data
 * @len: Pointer to length of image data
 * @max: The maximum allowed length of the data in the image data field
 * @follow_on: Check that this many bytes exist beyond the end of the image data
 *
 * Returns: 0 if ok, -1 on error
 */
static inline int dn_check_idf(unsigned char **pptr, int *len, unsigned char max, unsigned char follow_on)
{
	unsigned char *ptr = *pptr;
	unsigned char flen = *ptr++;

	(*len)--;
	if (flen > max)
		return -1;
	if ((flen + follow_on) > *len)
		return -1;

	*len -= flen;
	*pptr = ptr + flen;
	return 0;
}

/*
 * Table of reason codes to pass back to node which sent us a badly
 * formed message, plus text messages for the log. A zero entry in
 * the reason field means "don't reply" otherwise a disc init is sent with
 * the specified reason code.
 */
static struct {
	unsigned short reason;
	const char *text;
} ci_err_table[] = {
 { 0,             "CI: Truncated message" },
 { NSP_REASON_ID, "CI: Destination username error" },
 { NSP_REASON_ID, "CI: Destination username type" },
 { NSP_REASON_US, "CI: Source username error" },
 { 0,             "CI: Truncated at menuver" },
 { 0,             "CI: Truncated before access or user data" },
 { NSP_REASON_IO, "CI: Access data format error" },
 { NSP_REASON_IO, "CI: User data format error" }
};

/*
 * This function uses a slightly different lookup method
 * to find its sockets, since it searches on object name/number
 * rather than port numbers. Various tests are done to ensure that
 * the incoming data is in the correct format before it is queued to
 * a socket.
 */
static struct sock *dn_find_listener(struct sk_buff *skb, unsigned short *reason)
{
	struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
	struct nsp_conn_init_msg *msg = (struct nsp_conn_init_msg *)skb->data;
	struct sockaddr_dn dstaddr;
	struct sockaddr_dn srcaddr;
	unsigned char type = 0;
	int dstlen;
	int srclen;
	unsigned char *ptr;
	int len;
	int err = 0;
	unsigned char menuver;

	memset(&dstaddr, 0, sizeof(struct sockaddr_dn));
	memset(&srcaddr, 0, sizeof(struct sockaddr_dn));

	/*
	 * 1. Decode & remove message header
	 */
	cb->src_port = msg->srcaddr;
	cb->dst_port = msg->dstaddr;
	cb->services = msg->services;
	cb->info     = msg->info;
	cb->segsize  = dn_ntohs(msg->segsize);

	if (skb->len < sizeof(*msg))
		goto err_out;

	skb_pull(skb, sizeof(*msg));

	len = skb->len;
	ptr = skb->data;

	/*
	 * 2. Check destination end username format
	 */
	dstlen = dn_username2sockaddr(ptr, len, &dstaddr, &type);
	err++;
	if (dstlen < 0)
		goto err_out;

	err++;
	if (type > 1)
		goto err_out;

	len -= dstlen;
	ptr += dstlen;

	/*
	 * 3. Check source end username format
	 */
	srclen = dn_username2sockaddr(ptr, len, &srcaddr, &type);
	err++;
	if (srclen < 0)
		goto err_out;

	len -= srclen;
	ptr += srclen;
	err++;
	if (len < 1)
		goto err_out;

	menuver = *ptr;
	ptr++;
	len--;

	/*
	 * 4. Check that optional data actually exists if menuver says it does
	 */
	err++;
	if ((menuver & (DN_MENUVER_ACC | DN_MENUVER_USR)) && (len < 1))
		goto err_out;

	/*
	 * 5. Check optional access data format
	 */
	err++;
	if (menuver & DN_MENUVER_ACC) {
		if (dn_check_idf(&ptr, &len, 39, 1))
			goto err_out;
		if (dn_check_idf(&ptr, &len, 39, 1))
			goto err_out;
		if (dn_check_idf(&ptr, &len, 39, (menuver & DN_MENUVER_USR) ? 1 : 0))
			goto err_out;
	}

	/*
	 * 6. Check optional user data format
	 */
	err++;
	if (menuver & DN_MENUVER_USR) {
		if (dn_check_idf(&ptr, &len, 16, 0))
			goto err_out;
	}

	/*
	 * 7. Look up socket based on destination end username
	 */
	return dn_sklist_find_listener(&dstaddr);
err_out:
	dn_log_martian(skb, ci_err_table[err].text);
	*reason = ci_err_table[err].reason;
	return NULL;
}


static void dn_nsp_conn_init(struct sock *sk, struct sk_buff *skb)
{
	if (sk->ack_backlog >= sk->max_ack_backlog) {
		kfree_skb(skb);
		return;
	}

	sk->ack_backlog++;
	skb_queue_tail(&sk->receive_queue, skb);
	sk->state_change(sk);
}

static void dn_nsp_conn_conf(struct sock *sk, struct sk_buff *skb)
{
	struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
	struct dn_scp *scp = &sk->protinfo.dn;

	if (skb->len < 3)
		goto out;

	cb->services = *skb->data;
	cb->info = *(skb->data+1);
	skb_pull(skb, 2);
	cb->segsize = dn_ntohs(*(__u16 *)skb->data);
	skb_pull(skb, 2);

	/*
	 * FIXME: Check out services and info fields to check that
	 * we can talk to this kind of node.
	 */

	if ((scp->state == DN_CI) || (scp->state == DN_CD)) {
		scp->persist = 0;
                scp->addrrem = cb->src_port;
                sk->state = TCP_ESTABLISHED;
                scp->state = DN_RUN;

		if (scp->mss > cb->segsize)
			scp->mss = cb->segsize;
		if (scp->mss < 230)
			scp->mss = 230;

		if (skb->len > 0) {
			unsigned char dlen = *skb->data;
			if ((dlen <= 16) && (dlen <= skb->len)) {
				scp->conndata_in.opt_optl = dlen;
				memcpy(scp->conndata_in.opt_data, skb->data + 1, dlen);
			}
		}
                dn_nsp_send_lnk(sk, DN_NOCHANGE);
                if (!sk->dead)
                	sk->state_change(sk);
        }

out:
        kfree_skb(skb);
}

static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
{
	struct dn_scp *scp = &sk->protinfo.dn;

	if (scp->state == DN_CI) {
		scp->state = DN_CD;
		scp->persist = 0;
	}

	kfree_skb(skb);
}

static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
{
	struct dn_scp *scp = &sk->protinfo.dn;
	struct dn_skb_cb *cb = (struct dn_skb_cb *)skb->cb;
	unsigned short reason;

	if (skb->len < 2)
		goto out;

	reason = dn_ntohs(*(__u16 *)skb->data);
	skb_pull(skb, 2);

	scp->discdata_in.opt_status = reason;
	scp->discdata_in.opt_optl   = 0;
	memset(scp->discdata_in.opt_data, 0, 16);

	if (skb->len > 0) {
		unsigned char dlen = *skb->data;
		if ((dlen <= 16) && (dlen <= skb->len)) {
			scp->discdata_in.opt_optl = dlen;
			memcpy(scp->discdata_in.opt_data, skb->data + 1, dlen);
		}
	}

	scp->addrrem = cb->src_port;
	sk->state    = TCP_CLOSE;

	switch(scp->state) {
		case DN_CI:
		case DN_CD:
			scp->state = DN_RJ;
			break;
		case DN_RUN:
			sk->shutdown |= SHUTDOWN_MASK;
			scp->state = DN_DN;
			break;
		case DN_DI:
			scp->state = DN_DIC;
			break;
	}

	if (!sk->dead) {
		if (sk->socket->state != SS_UNCONNECTED)
			sk->socket->state = SS_DISCONNECTING;
		sk->state_change(sk);
	}

	dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
	scp->persist_fxn = dn_destroy_timer;
	scp->persist = dn_nsp_persist(sk);

out: