ipsec_esp.c

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		}
		KLIPS_PRINTMORE(debug_rcv & DB_RX_IPAD,
				" %02x",
				idat[irs->ilen - 2 - padlen + i - 1]);
		if(i != idat[irs->ilen - 2 - padlen + i - 1]) {
			badpad = 1;
		}
		if((i % 16) == 0) {
			KLIPS_PRINTMORE(debug_rcv & DB_RX_IPAD,
					"\n");
		}
	}
	if((i % 16) != 1) {
		KLIPS_PRINTMORE(debug_rcv & DB_RX_IPAD,
						"\n");
	}
	if(badpad) {
		KLIPS_PRINT(debug_rcv & DB_RX_IPAD,
			    "klips_debug:ipsec_rcv: "
			    "warning, decrypted packet from %s has bad padding\n",
			    irs->ipsaddr_txt);
		KLIPS_PRINT(debug_rcv & DB_RX_IPAD,
			    "klips_debug:ipsec_rcv: "
			    "...may be bad decryption -- not dropped\n");
		ipsp->ips_errs.ips_encpad_errs += 1;
	}

	KLIPS_PRINT(debug_rcv & DB_RX_IPAD,
		    "klips_debug:ipsec_rcv: "
		    "packet decrypted from %s: next_header = %d, padding = %d\n",
		    irs->ipsaddr_txt,
		    irs->next_header,
		    pad - 2 - irs->authlen);

	irs->ipp->tot_len = htons(ntohs(irs->ipp->tot_len) - (esphlen + pad));

	/*
	 * move the IP header forward by the size of the ESP header, which
	 * will remove the the ESP header from the packet.
	 */
	memmove((void *)(skb->data + esphlen),
		(void *)(skb->data), irs->iphlen);

	ipsec_rcv_dmp("esp postmove", skb->data, skb->len);

	/* skb_pull below, will move up by esphlen */

	/* XXX not clear how this can happen, as the message indicates */
	if(skb->len < esphlen) {
		printk(KERN_WARNING
		       "klips_error:ipsec_rcv: "
		       "tried to skb_pull esphlen=%d, %d available.  This should never happen, please report.\n",
		       esphlen, (int)(skb->len));
		return IPSEC_RCV_ESP_DECAPFAIL;
	}
	skb_pull(skb, esphlen);

	irs->ipp = (struct iphdr *)skb->data;

	ipsec_rcv_dmp("esp postpull", skb->data, skb->len);

	/* now, trip off the padding from the end */
	KLIPS_PRINT(debug_rcv & DB_RX_PKTRX,
		    "klips_debug:ipsec_rcv: "
		    "trimming to %d.\n",
		    irs->len - esphlen - pad);
	if(pad + esphlen <= irs->len) {
		skb_trim(skb, irs->len - esphlen - pad);
	} else {
		KLIPS_PRINT(debug_rcv & DB_RX_PKTRX,
			    "klips_debug:ipsec_rcv: "
			    "bogus packet, size is zero or negative, dropping.\n");
		return IPSEC_RCV_DECAPFAIL;
	}

	return IPSEC_RCV_OK;
}

enum ipsec_xmit_value
ipsec_xmit_esp_setup(struct ipsec_xmit_state *ixs)
{
  __u32 iv[2];
  struct esphdr *espp;
  int ilen = 0;
  int padlen = 0, i;
  unsigned char *dat;
  unsigned char *idat, *pad;
  __u8 hash[AH_AMAX];
  union {
#ifdef CONFIG_KLIPS_AUTH_HMAC_MD5
    MD5_CTX md5;
#endif /* CONFIG_KLIPS_AUTH_HMAC_MD5 */
#ifdef CONFIG_KLIPS_AUTH_HMAC_SHA1
    SHA1_CTX sha1;
#endif /* CONFIG_KLIPS_AUTH_HMAC_SHA1 */
  } tctx;

  dat = (unsigned char *)ixs->iph;

  espp = (struct esphdr *)(dat + ixs->iphlen);
  espp->esp_spi = ixs->ipsp->ips_said.spi;
  espp->esp_rpl = htonl(++(ixs->ipsp->ips_replaywin_lastseq));
  
  switch(ixs->ipsp->ips_encalg) {
#if defined(CONFIG_KLIPS_ENC_3DES)
#ifdef CONFIG_KLIPS_ENC_3DES
  case ESP_3DES:
#endif /* CONFIG_KLIPS_ENC_3DES */
    iv[0] = *((__u32*)&(espp->esp_iv)    ) =
      ((__u32*)(ixs->ipsp->ips_iv))[0];
    iv[1] = *((__u32*)&(espp->esp_iv) + 1) =
      ((__u32*)(ixs->ipsp->ips_iv))[1];
    break;
#endif /* defined(CONFIG_KLIPS_ENC_3DES) */
  default:
    ixs->stats->tx_errors++;
    return IPSEC_XMIT_ESP_BADALG;
  }
		
  idat = dat + ixs->iphlen + sizeof(struct esphdr);
  ilen = ixs->skb->len - (ixs->iphlen + sizeof(struct esphdr) + ixs->authlen);
  
  /* Self-describing padding */
  pad = &dat[ixs->skb->len - ixs->tailroom];
  padlen = ixs->tailroom - 2 - ixs->authlen;
  for (i = 0; i < padlen; i++) {
    pad[i] = i + 1; 
  }
  dat[ixs->skb->len - ixs->authlen - 2] = padlen;
  
  dat[ixs->skb->len - ixs->authlen - 1] = ixs->iph->protocol;
  ixs->iph->protocol = IPPROTO_ESP;
  
  switch(ixs->ipsp->ips_encalg) {
#ifdef CONFIG_KLIPS_ENC_3DES
  case ESP_3DES:
    des_ede3_cbc_encrypt((des_cblock *)idat,
			 (des_cblock *)idat,
			 ilen,
			 ((struct des_eks *)(ixs->ipsp->ips_key_e))[0].ks,
			 ((struct des_eks *)(ixs->ipsp->ips_key_e))[1].ks,
			 ((struct des_eks *)(ixs->ipsp->ips_key_e))[2].ks,
			 (des_cblock *)iv, 1);
    break;
#endif /* CONFIG_KLIPS_ENC_3DES */
  default:
    ixs->stats->tx_errors++;
    return IPSEC_XMIT_ESP_BADALG;
  }
  
  switch(ixs->ipsp->ips_encalg) {
#if defined(CONFIG_KLIPS_ENC_3DES)
#ifdef CONFIG_KLIPS_ENC_3DES
  case ESP_3DES:
#endif /* CONFIG_KLIPS_ENC_3DES */
    /* XXX update IV with the last 8 octets of the encryption */
#if KLIPS_IMPAIRMENT_ESPIV_CBC_ATTACK
    ((__u32*)(ixs->ipsp->ips_iv))[0] =
      ((__u32 *)(idat))[(ilen >> 2) - 2];
    ((__u32*)(ixs->ipsp->ips_iv))[1] =
      ((__u32 *)(idat))[(ilen >> 2) - 1];
#else /* KLIPS_IMPAIRMENT_ESPIV_CBC_ATTACK */
    prng_bytes(&ipsec_prng, (char *)ixs->ipsp->ips_iv, EMT_ESPDES_IV_SZ); 
#endif /* KLIPS_IMPAIRMENT_ESPIV_CBC_ATTACK */
    break;
#endif /* defined(CONFIG_KLIPS_ENC_3DES) */
  default:
    ixs->stats->tx_errors++;
    return IPSEC_XMIT_ESP_BADALG;
  }
  
  switch(ixs->ipsp->ips_authalg) {
#ifdef CONFIG_KLIPS_AUTH_HMAC_MD5
  case AH_MD5:
    ipsec_xmit_dmp("espp", (char*)espp, ixs->skb->len - ixs->iphlen - ixs->authlen);
    tctx.md5 = ((struct md5_ctx*)(ixs->ipsp->ips_key_a))->ictx;
    ipsec_xmit_dmp("ictx", (char*)&tctx.md5, sizeof(tctx.md5));
    osMD5Update(&tctx.md5, (caddr_t)espp, ixs->skb->len - ixs->iphlen - ixs->authlen);
    ipsec_xmit_dmp("ictx+dat", (char*)&tctx.md5, sizeof(tctx.md5));
    osMD5Final(hash, &tctx.md5);
    ipsec_xmit_dmp("ictx hash", (char*)&hash, sizeof(hash));
    tctx.md5 = ((struct md5_ctx*)(ixs->ipsp->ips_key_a))->octx;
    ipsec_xmit_dmp("octx", (char*)&tctx.md5, sizeof(tctx.md5));
    osMD5Update(&tctx.md5, hash, AHMD596_ALEN);
    ipsec_xmit_dmp("octx+hash", (char*)&tctx.md5, sizeof(tctx.md5));
    osMD5Final(hash, &tctx.md5);
    ipsec_xmit_dmp("octx hash", (char*)&hash, sizeof(hash));
    memcpy(&(dat[ixs->skb->len - ixs->authlen]), hash, ixs->authlen);
    
    /* paranoid */
    memset((caddr_t)&tctx.md5, 0, sizeof(tctx.md5));
    memset((caddr_t)hash, 0, sizeof(*hash));
    break;
#endif /* CONFIG_KLIPS_AUTH_HMAC_MD5 */
#ifdef CONFIG_KLIPS_AUTH_HMAC_SHA1
  case AH_SHA:
    tctx.sha1 = ((struct sha1_ctx*)(ixs->ipsp->ips_key_a))->ictx;
    SHA1Update(&tctx.sha1, (caddr_t)espp, ixs->skb->len - ixs->iphlen - ixs->authlen);
    SHA1Final(hash, &tctx.sha1);
    tctx.sha1 = ((struct sha1_ctx*)(ixs->ipsp->ips_key_a))->octx;
    SHA1Update(&tctx.sha1, hash, AHSHA196_ALEN);
    SHA1Final(hash, &tctx.sha1);
    memcpy(&(dat[ixs->skb->len - ixs->authlen]), hash, ixs->authlen);
    
    /* paranoid */
    memset((caddr_t)&tctx.sha1, 0, sizeof(tctx.sha1));
    memset((caddr_t)hash, 0, sizeof(*hash));
    break;
#endif /* CONFIG_KLIPS_AUTH_HMAC_SHA1 */
  case AH_NONE:
    break;
  default:
    ixs->stats->tx_errors++;
    return IPSEC_XMIT_AH_BADALG;
  }
#ifdef NET_21
  ixs->skb->h.raw = (unsigned char*)espp;
#endif /* NET_21 */

  return IPSEC_XMIT_OK;
}


struct xform_functions esp_xform_funcs[]={
	{	rcv_checks:         ipsec_rcv_esp_checks,
		rcv_setup_auth:     ipsec_rcv_esp_decrypt_setup,
		rcv_calc_auth:      ipsec_rcv_esp_authcalc,
		rcv_decrypt:        ipsec_rcv_esp_decrypt,

		xmit_setup:         ipsec_xmit_esp_setup,
		xmit_headroom:      sizeof(struct esphdr),
		xmit_needtailroom:  1,
	},
};

#ifdef NET_26
struct inet_protocol esp_protocol = {
  .handler = ipsec_rcv,
  .no_policy = 1,
};
#else
struct inet_protocol esp_protocol =
{
	ipsec_rcv,			/* ESP handler		*/
	NULL,				/* TUNNEL error control */
#ifdef NETDEV_25
	1,				/* no policy */
#else
	0,				/* next */
	IPPROTO_ESP,			/* protocol ID */
	0,				/* copy */
	NULL,				/* data */
	"ESP"				/* name */
#endif
};
#endif /* NET_26 */

#endif /* !CONFIG_KLIPS_ESP */


/*
 * $Log: ipsec_esp.c,v $
 * Revision 1.8  2004/09/14 00:22:57  mcr
 * 	adjustment of MD5* functions.
 *
 * Revision 1.7  2004/09/13 02:23:01  mcr
 * 	#define inet_protocol if necessary.
 *
 * Revision 1.6  2004/09/06 18:35:49  mcr
 * 	2.6.8.1 gets rid of inet_protocol->net_protocol compatibility,
 * 	so adjust for that.
 *
 * Revision 1.5  2004/08/17 03:27:23  mcr
 * 	klips 2.6 edits.
 *
 * Revision 1.4  2004/08/04 15:57:07  mcr
 * 	moved des .h files to include/des/ *
 * 	included 2.6 protocol specific things
 * 	started at NAT-T support, but it will require a kernel patch.
 *
 * Revision 1.3  2004/07/10 19:11:18  mcr
 * 	CONFIG_IPSEC -> CONFIG_KLIPS.
 *
 * Revision 1.2  2004/04/06 02:49:25  mcr
 * 	pullup of algo code from alg-branch.
 *
 *
 *
 */