ipsec_esp.c

This a good VPN source

/*
 * processing code for ESP
 * Copyright (C) 2003 Michael Richardson <[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 (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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.
 */

char ipsec_esp_c_version[] = "RCSID $Id: ipsec_esp.c,v 1.8 2004/09/14 00:22:57 mcr Exp $";
#include <linux/config.h>
#include <linux/version.h>

#define __NO_VERSION__
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */

#include "openswan/ipsec_param.h"

#ifdef MALLOC_SLAB
# include <linux/slab.h> /* kmalloc() */
#else /* MALLOC_SLAB */
# include <linux/malloc.h> /* kmalloc() */
#endif /* MALLOC_SLAB */
#include <linux/errno.h>  /* error codes */
#include <linux/types.h>  /* size_t */
#include <linux/interrupt.h> /* mark_bh */

#include <linux/netdevice.h>	/* struct device, and other headers */
#include <linux/etherdevice.h>	/* eth_type_trans */
#include <linux/ip.h>		/* struct iphdr */
#include <linux/skbuff.h>
#include <openswan.h>
#ifdef SPINLOCK
# ifdef SPINLOCK_23
#  include <linux/spinlock.h> /* *lock* */
# else /* SPINLOCK_23 */
#  include <asm/spinlock.h> /* *lock* */
# endif /* SPINLOCK_23 */
#endif /* SPINLOCK */
#ifdef NET_21
# include <asm/uaccess.h>
# include <linux/in6.h>
# define proto_priv cb
#endif /* NET21 */
#include <asm/checksum.h>
#include <net/ip.h>
#include <net/protocol.h>

#include "openswan/radij.h"
#include "openswan/ipsec_encap.h"
#include "openswan/ipsec_sa.h"

#include "openswan/ipsec_radij.h"
#include "openswan/ipsec_xform.h"
#include "openswan/ipsec_tunnel.h"
#include "openswan/ipsec_rcv.h"
#include "openswan/ipsec_xmit.h"

#include "openswan/ipsec_auth.h"

#ifdef CONFIG_KLIPS_ESP
#include "openswan/ipsec_esp.h"
#endif /* CONFIG_KLIPS_ESP */

#include "openswan/ipsec_proto.h"
#include "openswan/ipsec_alg.h"

#ifdef CONFIG_KLIPS_ESP
enum ipsec_rcv_value
ipsec_rcv_esp_checks(struct ipsec_rcv_state *irs,
		     struct sk_buff *skb)
{
	__u8 proto;
	int len;	/* packet length */

	len = skb->len;
	proto = irs->ipp->protocol;

	/* XXX this will need to be 8 for IPv6 */
	if ((proto == IPPROTO_ESP) && ((len - irs->iphlen) % 4)) {
		printk("klips_error:ipsec_rcv: "
		       "got packet with content length = %d from %s -- should be on 4 octet boundary, packet dropped\n",
		       len - irs->iphlen,
		       irs->ipsaddr_txt);
		if(irs->stats) {
			irs->stats->rx_errors++;
		}
		return IPSEC_RCV_BADLEN;
	}

	if(skb->len < (irs->hard_header_len + sizeof(struct iphdr) + sizeof(struct esphdr))) {
		KLIPS_PRINT(debug_rcv & DB_RX_INAU,
			    "klips_debug:ipsec_rcv: "
			    "runt esp packet of skb->len=%d received from %s, dropped.\n",
			    skb->len,
			    irs->ipsaddr_txt);
		if(irs->stats) {
			irs->stats->rx_errors++;
		}
		return IPSEC_RCV_BADLEN;
	}

	irs->protostuff.espstuff.espp = (struct esphdr *)(skb->data + irs->iphlen);
	irs->said.spi = irs->protostuff.espstuff.espp->esp_spi;

	return IPSEC_RCV_OK;
}

enum ipsec_rcv_value
ipsec_rcv_esp_decrypt_setup(struct ipsec_rcv_state *irs,
			    struct sk_buff *skb,
			    __u32          *replay,
			    unsigned char **authenticator)
{
	struct esphdr *espp = irs->protostuff.espstuff.espp;

	KLIPS_PRINT(debug_rcv,
		    "klips_debug:ipsec_rcv: "
		    "packet from %s received with seq=%d (iv)=0x%08x%08x iplen=%d esplen=%d sa=%s\n",
		    irs->ipsaddr_txt,
		    (__u32)ntohl(espp->esp_rpl),
		    (__u32)ntohl(*((__u32 *)(espp->esp_iv)    )),
		    (__u32)ntohl(*((__u32 *)(espp->esp_iv) + 1)),
		    irs->len,
		    irs->ilen,
		    irs->sa_len ? irs->sa : " (error)");

	*replay = ntohl(espp->esp_rpl);
	*authenticator = &(skb->data[irs->len - irs->authlen]);

	return IPSEC_RCV_OK;
}

enum ipsec_rcv_value
ipsec_rcv_esp_authcalc(struct ipsec_rcv_state *irs,
		       struct sk_buff *skb)
{
	struct auth_alg *aa;
	struct esphdr *espp = irs->protostuff.espstuff.espp;
	union {
		MD5_CTX		md5;
		SHA1_CTX	sha1;
	} tctx;

#ifdef CONFIG_KLIPS_ALG
	if (irs->ipsp->ips_alg_auth) {
		KLIPS_PRINT(debug_rcv,
				"klips_debug:ipsec_rcv: "
				"ipsec_alg hashing proto=%d... ",
				irs->said.proto);
		if(irs->said.proto == IPPROTO_ESP) {
			ipsec_alg_sa_esp_hash(irs->ipsp,
					(caddr_t)espp, irs->ilen,
					irs->hash, AHHMAC_HASHLEN);
			return IPSEC_RCV_OK;
		}
		return IPSEC_RCV_BADPROTO;
	}
#endif
	aa = irs->authfuncs;

	/* copy the initialized keying material */
	memcpy(&tctx, irs->ictx, irs->ictx_len);

	(*aa->update)((void *)&tctx, (caddr_t)espp, irs->ilen);

	(*aa->final)(irs->hash, (void *)&tctx);

	memcpy(&tctx, irs->octx, irs->octx_len);

	(*aa->update)((void *)&tctx, irs->hash, aa->hashlen);
	(*aa->final)(irs->hash, (void *)&tctx);

	return IPSEC_RCV_OK;
}


enum ipsec_rcv_value
ipsec_rcv_esp_decrypt(struct ipsec_rcv_state *irs)
{
	struct ipsec_sa *ipsp = irs->ipsp;
	struct esphdr *espp = irs->protostuff.espstuff.espp;
	int esphlen = 0;
	__u8 *idat;	/* pointer to content to be decrypted/authenticated */
	__u32 iv[2];
	int pad = 0, padlen;
	int badpad = 0;
	int i;
	struct sk_buff *skb;
#ifdef CONFIG_KLIPS_ALG
	struct ipsec_alg_enc *ixt_e=NULL;
#endif /* CONFIG_KLIPS_ALG */

	skb=irs->skb;

	idat = skb->data + irs->iphlen;

#ifdef CONFIG_KLIPS_ALG
	if ((ixt_e=ipsp->ips_alg_enc)) {
		esphlen = ESP_HEADER_LEN + ixt_e->ixt_ivlen/8;
		KLIPS_PRINT(debug_rcv,
				"klips_debug:ipsec_rcv: "
				"encalg=%d esphlen=%d\n",
				ipsp->ips_encalg, esphlen);
	} else
#endif /* CONFIG_KLIPS_ALG */
	switch(ipsp->ips_encalg) {
	case ESP_3DES:
		iv[0] = *((__u32 *)(espp->esp_iv)    );
		iv[1] = *((__u32 *)(espp->esp_iv) + 1);
		esphlen = sizeof(struct esphdr);
		break;
	default:
		ipsp->ips_errs.ips_alg_errs += 1;
		if(irs->stats) {
			irs->stats->rx_errors++;
		}
		return IPSEC_RCV_ESP_BADALG;
	}

	idat += esphlen;
	irs->ilen -= esphlen;

#ifdef CONFIG_KLIPS_ALG
	if (ixt_e)
	{
		if (ipsec_alg_esp_encrypt(ipsp, 
					idat, irs->ilen, espp->esp_iv, 
					IPSEC_ALG_DECRYPT) <= 0)
		{
			printk("klips_error:ipsec_rcv: "
					"got packet with esplen = %d "
					"from %s -- should be on "
					"ENC(%d) octet boundary, "
					"packet dropped\n",
					irs->ilen,
					irs->ipsaddr_txt,
					ipsp->ips_encalg);
			if(irs->stats) {
				irs->stats->rx_errors++;
			}
			return IPSEC_RCV_BAD_DECRYPT;
		}
	} else
#endif /* CONFIG_KLIPS_ALG */
	switch(ipsp->ips_encalg) {
	case ESP_3DES:
		if ((irs->ilen) % 8) {
			ipsp->ips_errs.ips_encsize_errs += 1;
			printk("klips_error:ipsec_rcv: "
			       "got packet with esplen = %d from %s -- should be on 8 octet boundary, packet dropped\n",
			       irs->ilen,
			       irs->ipsaddr_txt);
			if(irs->stats) {
				irs->stats->rx_errors++;
			}
			return IPSEC_RCV_3DES_BADBLOCKING;
		}
		des_ede3_cbc_encrypt((des_cblock *)idat,
				     (des_cblock *)idat,
				     irs->ilen,
				     ((struct des_eks *)(ipsp->ips_key_e))[0].ks,
				     ((struct des_eks *)(ipsp->ips_key_e))[1].ks,
				     ((struct des_eks *)(ipsp->ips_key_e))[2].ks,
				     (des_cblock *)iv, 0);
		break;
	}

	ipsec_rcv_dmp("postdecrypt", skb->data, skb->len);

	irs->next_header = idat[irs->ilen - 1];
	padlen = idat[irs->ilen - 2];
	pad = padlen + 2 + irs->authlen;

	KLIPS_PRINT(debug_rcv & DB_RX_IPAD,
		    "klips_debug:ipsec_rcv: "
		    "padlen=%d, contents: 0x<offset>: 0x<value> 0x<value> ...\n",
		    padlen);

	for (i = 1; i <= padlen; i++) {
		if((i % 16) == 1) {
			KLIPS_PRINT(debug_rcv & DB_RX_IPAD,
				    "klips_debug:           %02x:",
				    i - 1);