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ike.c
1168 lines (1025 loc) · 32.1 KB
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ike.c
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/*
* fiked - a fake IKE PSK+XAUTH daemon based on vpnc
* Copyright (C) 2005, Daniel Roethlisberger <daniel@roe.ch>
*
* 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.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see http://www.gnu.org/copyleft/
*/
#include "ike.h"
#include "datagram.h"
#include "send_dgm.h"
#include "log.h"
#include "peer_ctx.h"
#include "config.h"
#include "mem.h"
#include "vpnc/math_group.h"
#include "vpnc/dh.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gcrypt.h>
/*
* W A R N I N G / D I S C L A I M E R
*
* This code is unsuitable for building a genuine IKE responder!
* It's very likely to be any or all of: insecure, incompatible,
* inefficient, unstable, unportable, or outright broken.
* There's hardly enough sanity checking and failure resistance.
* If you want genuine IKE source code, look for a proper
* implementation instead. This is a quick hack to snarf XAUTH
* credentials from clients, not a full implementation of IKE.
* You've been warned.
*/
/* forward declarations */
void ike_process_new(peer_ctx *ctx, struct isakmp_packet *ikp);
/* minimum */
static inline int
min(int a, int b)
{
return (a < b) ? a : b;
}
/* vendor ids */
static const uint8_t xauth_vid[] = XAUTH_VENDOR_ID;
static const uint8_t unity_vid[] = UNITY_VENDOR_ID;
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* IKE encryption and decryption routines *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Encrypts or decrypts the buffer buf.
* Buf must already be padded to blocksize of the encryption algorithm in use.
*/
void
ike_crypt_crypt(int algo, int enc, uint8_t *buf, size_t buflen,
uint8_t *key, size_t keylen, uint8_t *iv, size_t ivlen)
{
gcry_cipher_hd_t crypt_ctx;
gcry_cipher_open(&crypt_ctx, algo, GCRY_CIPHER_MODE_CBC, 0);
gcry_cipher_setkey(crypt_ctx, key, keylen);
gcry_cipher_setiv(crypt_ctx, iv, ivlen);
if (!enc)
gcry_cipher_decrypt(crypt_ctx, buf, buflen, NULL, 0);
else
gcry_cipher_encrypt(crypt_ctx, buf, buflen, NULL, 0);
gcry_cipher_close(crypt_ctx);
}
/*
* Generic encryption/decryption routine.
* If payload of ikp is encrypted, decrypt it, if not, encrypt it.
* Handles phase 1 and phase 2 enc/dec, and IV generation.
*/
int
ike_crypt(peer_ctx *ctx, struct isakmp_packet *ikp)
{
/*
* phase 1, first: iv = hash(i_dh_public r_dh_public)
* phase 1, rest: iv = last_block_phase1
* phase 2, first: iv = hash(last_block_phase1 message_id)
* phase 2, rest: iv = last_block_phase2
*/
uint8_t *iv = NULL;
int update_iv = 1;
uint8_t *fp = NULL;
size_t fp_len;
uint8_t fp_type;
gcry_md_hd_t md_ctx;
int reject = 0;
message_iv *msg_iv = NULL;
int enc = !(ikp->flags & ISAKMP_FLAG_E);
switch (ctx->state) {
case STATE_PHASE1:
/* iv0 not set means no phase 1 encrypted packets yet */
if (!ctx->iv0) {
/* generate initial phase 1 iv */
gcry_md_open(&md_ctx, ctx->md_algo, 0);
gcry_md_write(md_ctx, ctx->dh_i_public,
dh_getlen(ctx->dh_group));
gcry_md_write(md_ctx, ctx->dh_r_public,
dh_getlen(ctx->dh_group));
gcry_md_final(md_ctx);
mem_allocate(&ctx->iv0, ctx->blk_len);
memcpy(ctx->iv0, gcry_md_read(md_ctx, 0), ctx->blk_len);
gcry_md_close(md_ctx);
}
iv = ctx->iv0;
break;
case STATE_PHASE2:
/* fetch message_iv for this exchange */
msg_iv = message_iv_get(ikp->message_id, &ctx->msg_iv);
if (!msg_iv->iv) {
/* generate initial phase 2 iv */
gcry_md_open(&md_ctx, ctx->md_algo, 0);
gcry_md_write(md_ctx, ctx->iv0, ctx->blk_len);
gcry_md_putc(md_ctx, (ikp->message_id >> 24) & 0xFF);
gcry_md_putc(md_ctx, (ikp->message_id >> 16) & 0xFF);
gcry_md_putc(md_ctx, (ikp->message_id >> 8) & 0xFF);
gcry_md_putc(md_ctx, (ikp->message_id) & 0xFF);
gcry_md_final(md_ctx);
mem_allocate(&msg_iv->iv, ctx->md_len);
memcpy(msg_iv->iv, gcry_md_read(md_ctx, 0),
ctx->blk_len);
gcry_md_close(md_ctx);
}
iv = msg_iv->iv;
break;
default:
log_printf(ctx, "ike_crypt in illegal state %d, packet ignored",
ctx->state);
return -1;
break;
}
if (enc) {
/* flatten and encrypt payload */
fp_type = ikp->u.payload->type;
flatten_isakmp_payload(ikp->u.payload, &fp, &fp_len,
ctx->blk_len);
ike_crypt_crypt(ctx->algo, enc, fp, fp_len,
ctx->key, ctx->key_len, iv, ctx->blk_len);
/* swap payload for encrypted buffer */
free_isakmp_payload(ikp->u.payload);
ikp->u.enc.length = fp_len;
ikp->u.enc.data = NULL; /* don't free */
mem_allocate(&ikp->u.enc.data, ikp->u.enc.length);
memcpy(ikp->u.enc.data, fp, ikp->u.enc.length);
ikp->u.enc.type = fp_type;
/* update IV with last cipher block */
if (update_iv) {
memcpy(iv, fp + fp_len - ctx->blk_len, ctx->blk_len);
}
} else { /* dec */
uint8_t *newiv = NULL;
/* copy encrypted buffer */
fp_len = ikp->u.enc.length;
mem_allocate(&fp, fp_len);
memcpy(fp, ikp->u.enc.data, fp_len);
/* store last cipher block */
if (update_iv) {
mem_allocate(&newiv, ctx->blk_len);
memcpy(newiv, fp + fp_len - ctx->blk_len, ctx->blk_len);
}
/* decrypt encrypted buffer */
ike_crypt_crypt(ctx->algo, enc, fp, fp_len,
ctx->key, ctx->key_len, iv, ctx->blk_len);
/* copy stored last cipher block to iv */
if (update_iv) {
memcpy(iv, newiv, ctx->blk_len);
mem_free(&newiv);
}
/* swap encrypted buffer for decoded payload */
const uint8_t *cfp = fp;
struct isakmp_payload *pl = parse_isakmp_payload(
ikp->u.enc.type,
&cfp, &fp_len, &reject);
if (reject) {
log_printf(ctx,
"illegal decrypted payload (%d), packet ignored",
reject);
mem_free(&fp);
return reject;
}
free(ikp->u.enc.data);
ikp->u.payload = pl;
}
mem_free(&fp);
/* flip the "encrypted" flag */
ikp->flags ^= ISAKMP_FLAG_E;
return 0;
}
/*
* Return phase 2 authentication hash for payload pl.
* Returned hash must be freed.
*/
uint8_t *
phase2_hash(peer_ctx *ctx, uint32_t message_id, struct isakmp_payload *pl)
{
gcry_md_hd_t md_ctx;
uint8_t *pl_flat;
size_t pl_size;
uint8_t *hash = NULL;
mem_allocate(&hash, ctx->md_len);
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->skeyid_a, ctx->md_len);
gcry_md_putc(md_ctx, (message_id >> 24) & 0xFF);
gcry_md_putc(md_ctx, (message_id >> 16) & 0xFF);
gcry_md_putc(md_ctx, (message_id >> 8) & 0xFF);
gcry_md_putc(md_ctx, (message_id) & 0xFF);
/* XXX: nonce? */
if (pl) {
flatten_isakmp_payload(pl, &pl_flat, &pl_size, 1);
gcry_md_write(md_ctx, pl_flat, pl_size);
free(pl_flat);
} else {
gcry_md_putc(md_ctx, 0);
}
gcry_md_final(md_ctx);
memcpy(hash, gcry_md_read(md_ctx, 0), ctx->md_len);
gcry_md_close(md_ctx);
return hash;
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Security Association payload helpers *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Is this a supported SA transform? Return 1 if yes, 0 if not.
* We do not prioritize, instead we just select the very first supported
* transform.
*/
int
sa_transform_matches(peer_ctx* ctx, struct isakmp_payload *t)
{
struct isakmp_attribute *enc = NULL;
struct isakmp_attribute *keylen = NULL;
struct isakmp_attribute *hash = NULL;
struct isakmp_attribute *auth_method = NULL;
struct isakmp_attribute *group_desc = NULL;
for (struct isakmp_attribute *a = t->u.t.attributes; a; a = a->next) {
switch (a->type) {
case IKE_ATTRIB_ENC:
enc = a;
break;
case IKE_ATTRIB_KEY_LENGTH:
keylen = a;
break;
case IKE_ATTRIB_HASH:
hash = a;
break;
case IKE_ATTRIB_AUTH_METHOD:
auth_method = a;
break;
case IKE_ATTRIB_GROUP_DESC:
group_desc = a;
break;
default:
/* silently ignore */
break;
}
}
/* do we have all required attributes? */
if (!(enc && hash && auth_method && group_desc)) {
log_printf(ctx,
"missing attribute(s): enc=%p hash=%p am=%p gd=%p",
(void*)enc, (void*)hash, (void*)auth_method,
(void*)group_desc);
return 0;
}
/* we don't support anything other than PSK+XAUTH */
if (auth_method->u.attr_16 != IKE_AUTH_XAUTHInitPreShared)
return 0;
/* choose algorithms we support */
char *enc_txt = NULL;
char *md_txt = NULL;
char *dh_txt = NULL;
switch (enc->u.attr_16) {
case IKE_ENC_DES_CBC:
ctx->algo = GCRY_CIPHER_DES;
enc_txt = "DES";
break;
case IKE_ENC_3DES_CBC:
ctx->algo = GCRY_CIPHER_3DES;
enc_txt = "3DES";
break;
case IKE_ENC_AES_CBC:
if(!keylen)
return 0;
switch(keylen->u.attr_16) {
case 128:
ctx->algo = GCRY_CIPHER_AES128;
enc_txt = "AES128";
break;
case 192:
ctx->algo = GCRY_CIPHER_AES192;
enc_txt = "AES192";
break;
case 256:
ctx->algo = GCRY_CIPHER_AES256;
enc_txt = "AES256";
break;
default:
return 0;
}
break;
default:
return 0;
}
switch (hash->u.attr_16) {
case IKE_HASH_MD5:
ctx->md_algo = GCRY_MD_MD5;
md_txt = "MD5";
break;
case IKE_HASH_SHA:
ctx->md_algo = GCRY_MD_SHA1;
md_txt = "SHA1";
break;
default:
return 0;
}
switch (group_desc->u.attr_16) {
case IKE_GROUP_MODP_768:
if (ctx->dh_group)
group_free(ctx->dh_group);
ctx->dh_group = group_get(OAKLEY_GRP_1);
dh_txt = "DH1";
break;
case IKE_GROUP_MODP_1024:
if (ctx->dh_group)
group_free(ctx->dh_group);
ctx->dh_group = group_get(OAKLEY_GRP_2);
dh_txt = "DH2";
break;
case IKE_GROUP_MODP_1536:
if (ctx->dh_group)
group_free(ctx->dh_group);
ctx->dh_group = group_get(OAKLEY_GRP_5);
dh_txt = "DH5";
break;
default:
return 0;
}
log_printf(ctx, "using %s %s %s", enc_txt, md_txt, dh_txt);
/* set up lengths according to chosen algorithms */
ctx->md_len = gcry_md_get_algo_dlen(ctx->md_algo);
gcry_cipher_algo_info(ctx->algo, GCRYCTL_GET_BLKLEN, NULL,
&(ctx->blk_len));
gcry_cipher_algo_info(ctx->algo, GCRYCTL_GET_KEYLEN, NULL,
&(ctx->key_len));
return 1;
}
/*
* Walk proposal SA, choose a transform, copy relevant stuff to response SA.
*/
void
sa_transform_choose(peer_ctx* ctx, struct isakmp_payload *response,
struct isakmp_payload *proposal)
{
/* copy SA payload */
*response = *proposal;
response->u.sa.proposals = new_isakmp_payload(ISAKMP_PAYLOAD_P);
/* copy proposals payload */
*response->u.sa.proposals = *proposal->u.sa.proposals;
response->u.sa.proposals->u.p.spi = NULL;
mem_allocate(&response->u.sa.proposals->u.p.spi,
response->u.sa.proposals->u.p.spi_size);
memcpy(response->u.sa.proposals->u.p.spi,
proposal->u.sa.proposals->u.p.spi,
response->u.sa.proposals->u.p.spi_size);
response->u.sa.proposals->u.p.transforms =
new_isakmp_payload(ISAKMP_PAYLOAD_T);
/* find matching transform */
struct isakmp_payload *p;
for (p = proposal->u.sa.proposals->u.p.transforms; p; p = p->next) {
if (sa_transform_matches(ctx, p))
break;
}
if (!p) {
log_printf(ctx, "no matching algo proposal, ignoring request");
return;
}
/* copy chosen transform payload */
*response->u.sa.proposals->u.p.transforms = *p;
response->u.sa.proposals->u.p.transforms->next = NULL;
struct isakmp_attribute *ra = NULL;
for (struct isakmp_attribute *pa = p->u.t.attributes; pa; pa = pa->next) {
if (!ra) {
/* first attribute */
ra = response->u.sa.proposals->u.p.transforms->u.t.attributes =
new_isakmp_attribute(pa->type, NULL);
} else {
/* subsequent attributes */
ra->next = new_isakmp_attribute(pa->type, NULL);
ra = ra->next;
}
*ra = *pa;
ra->next = NULL;
switch (ra->af) {
case isakmp_attr_lots:
ra->u.lots.data = NULL; /* don't free */
mem_allocate(&ra->u.lots.data, ra->u.lots.length);
memcpy(ra->u.lots.data, pa->u.lots.data, ra->u.lots.length);
break;
case isakmp_attr_acl:
ra->u.acl.acl_ent = NULL; /* don't free */
mem_allocate(&ra->u.acl.acl_ent, ra->u.acl.count * sizeof(*ra->u.acl.acl_ent));
memcpy(ra->u.acl.acl_ent, pa->u.acl.acl_ent, ra->u.acl.count * sizeof(*ra->u.acl.acl_ent));
break;
default:
/* ignore */
break;
}
}
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Informational packet handler *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Process an IKE Informational packet.
* Packet must already be decrypted.
*/
void
ike_process_informational(peer_ctx *ctx, struct isakmp_packet *ikp)
{
if (ikp->flags & ISAKMP_FLAG_E) {
log_printf(ctx, "encrypted informational packet, reset state");
peer_ctx_reset(ctx);
return;
}
for (struct isakmp_payload *p = ikp->u.payload; p; p = p->next) {
switch (p->type) {
case ISAKMP_PAYLOAD_N:
switch (p->u.n.type) {
case ISAKMP_N_INVALID_PAYLOAD_TYPE:
log_printf(ctx,
"error from peer: invalid payload type, reset state");
peer_ctx_reset(ctx);
break;
case ISAKMP_N_CISCO_HEARTBEAT:
/* ignore */
break;
default:
log_printf(ctx,
"unhandled informational notification type 0x%02x, ignored",
p->u.n.type);
break;
}
break;
case ISAKMP_PAYLOAD_D:
case ISAKMP_PAYLOAD_HASH:
/* a real IKE responder would check the hash and drop
* the packet if invalid -- we just ignore it
*/
break;
default:
log_printf(ctx,
"unhandled informational payload type 0x%02x, ignored",
p->type);
break;
}}
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Phase 2 handlers *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
IKE Initiator IKE Responder
-------------- -----------------
<-- REQUEST(NAME="" PASSWORD="")
REPLY(NAME="joe" PASSWORD="foobar") -->
<-- SET(STATUS=OK)
ACK(STATUS) -->
*/
/*
* Begin XAUTH login.
* REQUEST(NAME="" PASSWORD="")
*/
void
ike_do_phase2_xauth_begin(peer_ctx *ctx)
{
struct isakmp_packet *r = new_isakmp_packet();
memcpy(r->i_cookie, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
memcpy(r->r_cookie, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
r->isakmp_version = ctx->isakmp_version;
r->exchange_type = ISAKMP_EXCHANGE_MODECFG_TRANSACTION;
r->flags = 0;
gcry_create_nonce((uint8_t*)&r->message_id, sizeof(r->message_id));
r->u.payload = new_isakmp_payload(ISAKMP_PAYLOAD_HASH);
r->u.payload->next = new_isakmp_payload(ISAKMP_PAYLOAD_MODECFG_ATTR);
r->u.payload->next->u.modecfg.type = ISAKMP_MODECFG_CFG_REQUEST;
r->u.payload->next->u.modecfg.attributes =
new_isakmp_attribute(ISAKMP_XAUTH_ATTRIB_USER_NAME,
new_isakmp_attribute(ISAKMP_XAUTH_ATTRIB_USER_PASSWORD, 0)
);
struct isakmp_attribute *a = r->u.payload->next->u.modecfg.attributes;
a->af = isakmp_attr_lots;
a->u.lots.length = 0;
a->u.lots.data = NULL;
a = a->next;
a->af = isakmp_attr_lots;
a->u.lots.length = 0;
a->u.lots.data = NULL;
/* send response */
datagram *dgm = datagram_new(0);
r->u.payload->u.hash.length = ctx->md_len;
r->u.payload->u.hash.data =
phase2_hash(ctx, r->message_id, r->u.payload->next);
ike_crypt(ctx, r);
mem_free(&dgm->data);
flatten_isakmp_packet(r, &dgm->data, &dgm->len, ctx->blk_len);
dgm->peer_addr = ctx->peer_addr;
send_datagram(ctx, dgm);
free_isakmp_packet(r);
datagram_free(dgm);
}
/*
* Handle XAUTH replies.
* REPLY(NAME="joe" PASSWORD="foobar")
*/
void
ike_do_phase2_xauth(peer_ctx *ctx, struct isakmp_packet *ikp)
{
for (struct isakmp_attribute *a =
ikp->u.payload->next->u.modecfg.attributes; a; a = a->next) {
switch (a->type) {
case ISAKMP_XAUTH_ATTRIB_USER_NAME:
mem_allocate(&ctx->xauth_username, a->u.lots.length + 1);
memcpy(ctx->xauth_username, a->u.lots.data, a->u.lots.length);
ctx->xauth_username[a->u.lots.length] = '\0';
log_printf(ctx, "Xauth username: %s",
ctx->xauth_username);
break;
case ISAKMP_XAUTH_ATTRIB_USER_PASSWORD:
mem_allocate(&ctx->xauth_password, a->u.lots.length + 1);
memcpy(ctx->xauth_password, a->u.lots.data, a->u.lots.length);
ctx->xauth_password[a->u.lots.length] = '\0';
log_printf(ctx, "Xauth password: %s",
ctx->xauth_password);
break;
case ISAKMP_XAUTH_ATTRIB_STATUS:
if (a->u.attr_16 == 0) {
log_printf(ctx,
"IKE session aborted by peer");
peer_ctx_reset(ctx);
return;
}
break;
default:
log_printf(ctx,
"unhandled modecfg attr type 0x%02x, ignored",
a->type);
break;
}
}
/* log credentials */
ctx->done = 1;
/* give client feedback in form of an auth failed message */
struct isakmp_packet *r = new_isakmp_packet();
memcpy(r->i_cookie, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
memcpy(r->r_cookie, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
r->isakmp_version = ctx->isakmp_version;
r->exchange_type = ISAKMP_EXCHANGE_MODECFG_TRANSACTION;
r->flags = 0;
gcry_create_nonce((uint8_t*)&r->message_id, sizeof(r->message_id));
r->u.payload = new_isakmp_payload(ISAKMP_PAYLOAD_HASH);
r->u.payload->next = new_isakmp_payload(ISAKMP_PAYLOAD_MODECFG_ATTR);
r->u.payload->next->u.modecfg.type = ISAKMP_MODECFG_CFG_SET;
r->u.payload->next->u.modecfg.attributes =
new_isakmp_attribute(ISAKMP_XAUTH_ATTRIB_STATUS, 0);
struct isakmp_attribute *a = r->u.payload->next->u.modecfg.attributes;
a->af = isakmp_attr_16;
a->u.attr_16 = 0;
/* send response */
datagram *dgm = datagram_new(0);
r->u.payload->u.hash.length = ctx->md_len;
r->u.payload->u.hash.data =
phase2_hash(ctx, r->message_id, r->u.payload->next);
ike_crypt(ctx, r);
mem_free(&dgm->data);
flatten_isakmp_packet(r, &dgm->data, &dgm->len, ctx->blk_len);
dgm->peer_addr = ctx->peer_addr;
send_datagram(ctx, dgm);
free_isakmp_packet(r);
datagram_free(dgm);
}
/*
* Process MODECFG packets.
*/
void
ike_process_phase2_modecfg(peer_ctx *ctx, struct isakmp_packet *ikp)
{
switch (ikp->u.payload->next->u.modecfg.type) {
case ISAKMP_MODECFG_CFG_REPLY:
ike_do_phase2_xauth(ctx, ikp);
break;
case ISAKMP_MODECFG_CFG_ACK:
/* final ACK(STATUS) for our SET(STATUS=FAIL) */
log_printf(ctx, "IKE session closed");
peer_ctx_reset(ctx);
break;
default:
log_printf(ctx, "unhandled modecfg type 0x%02x, ignored",
ikp->u.payload->next->u.modecfg.type);
break;
}
}
/*
* Process an IKE packet in STATE_PHASE2.
* Handles decryption.
*/
void
ike_process_phase2(peer_ctx *ctx, struct isakmp_packet *ikp) {
if (!(ikp->flags & ISAKMP_FLAG_E)) {
log_printf(ctx,
"unencrypted packet in STATE_PHASE2, reset state");
peer_ctx_reset(ctx);
ike_process_new(ctx, ikp);
return;
}
switch (ikp->exchange_type) {
case ISAKMP_EXCHANGE_MODECFG_TRANSACTION:
if (!ike_crypt(ctx, ikp))
ike_process_phase2_modecfg(ctx, ikp);
break;
case ISAKMP_EXCHANGE_INFORMATIONAL:
if (!ike_crypt(ctx, ikp))
ike_process_informational(ctx, ikp);
break;
default:
log_printf(ctx,
"unhandled exchange type 0x%02x in STATE_PHASE1, ignored",
ikp->exchange_type);
break;
}
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Phase 1 handlers *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Process an IKE Aggressive Mode packet in STATE_NEW.
*/
void
ike_do_phase1(peer_ctx *ctx, struct isakmp_packet *ikp)
{
/* get the payloads */
struct isakmp_payload *sa = NULL;
struct isakmp_payload *ke = NULL;
struct isakmp_payload *nonce = NULL;
struct isakmp_payload *id = NULL;
for (struct isakmp_payload *p = ikp->u.payload; p; p = p->next) {
switch (p->type) {
case ISAKMP_PAYLOAD_SA:
sa = p;
break;
case ISAKMP_PAYLOAD_KE:
ke = p;
break;
case ISAKMP_PAYLOAD_NONCE:
nonce = p;
break;
case ISAKMP_PAYLOAD_ID:
id = p;
break;
case ISAKMP_PAYLOAD_VID:
/* silently ignore for now */
break;
default:
log_printf(ctx,
"unhandled payload type 0x%02x, ignored",
p->type);
break;
}}
/* do we have all payloads? */
if (!(sa && ke && nonce && id)) {
log_printf(ctx,
"missing payload(s): sa=%p ke=%p nonce=%p id=%p, ignored",
(void*)sa, (void*)ke, (void*)nonce, (void*)id);
return;
}
/* heads up: the ipsec id */
switch (id->u.id.type) {
case ISAKMP_IPSEC_ID_FQDN:
case ISAKMP_IPSEC_ID_USER_FQDN:
case ISAKMP_IPSEC_ID_KEY_ID:
mem_allocate(&ctx->ipsec_id, id->u.id.length + 1);
memcpy(ctx->ipsec_id, id->u.id.data, id->u.id.length);
ctx->ipsec_id[id->u.id.length] = '\0';
ctx->ipsec_secret = (uint8_t*) strdup(psk_get_key(
(char*)ctx->ipsec_id,
ctx->cfg->keys));
log_printf(ctx, "IPSec ID: %s",
ctx->ipsec_id);
log_printf(ctx, "IPSec Secret: %s",
ctx->ipsec_secret);
break;
default:
log_printf(ctx,
"IPSec ID type %d is binary, processing packet anyway",
id->u.id.type);
break;
}
/* grab proto version */
ctx->isakmp_version = ikp->isakmp_version;
/* grab i_cookie */
memcpy(ctx->i_cookie, ikp->i_cookie, ISAKMP_COOKIE_LENGTH);
/* grab i_sa */
struct isakmp_payload *tmp = sa->next;
sa->next = NULL;
mem_free(&ctx->i_sa);
flatten_isakmp_payload(sa, &ctx->i_sa, &ctx->i_sa_len, 1);
sa->next = tmp;
/* grab dh_i_public */
mem_allocate(&ctx->dh_i_public, ke->u.ke.length);
memcpy(ctx->dh_i_public, ke->u.ke.data, ke->u.ke.length);
/* grab i_nonce */
mem_allocate(&ctx->i_nonce, nonce->u.nonce.length);
ctx->i_nonce_len = nonce->u.nonce.length;
memcpy(ctx->i_nonce, nonce->u.nonce.data, nonce->u.nonce.length);
/* grab i_id */
tmp = id->next;
id->next = NULL;
mem_free(&ctx->i_id);
flatten_isakmp_payload(id, &ctx->i_id, &ctx->i_id_len, 1);
id->next = tmp;
/* generate r_cookie */
gcry_create_nonce(ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
/* generate r_nonce */
ctx->r_nonce_len = ctx->i_nonce_len;
mem_allocate(&ctx->r_nonce, ctx->r_nonce_len);
gcry_create_nonce(ctx->r_nonce, ctx->r_nonce_len);
/* header */
struct isakmp_packet *r = new_isakmp_packet();
memcpy(r->i_cookie, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
memcpy(r->r_cookie, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
r->isakmp_version = ikp->isakmp_version;
r->exchange_type = ikp->exchange_type;
r->flags = 0;
r->message_id = ikp->message_id;
/* payload: sa */
r->u.payload = new_isakmp_payload(ISAKMP_PAYLOAD_SA);
sa_transform_choose(ctx, r->u.payload, sa);
struct isakmp_payload *p = r->u.payload;
/* complete dh key exchange */
mem_allocate(&ctx->dh_r_public, dh_getlen(ctx->dh_group));
dh_create_exchange(ctx->dh_group, ctx->dh_r_public);
mem_allocate(&ctx->dh_secret, dh_getlen(ctx->dh_group));
dh_create_shared(ctx->dh_group, ctx->dh_secret, ctx->dh_i_public);
/* payload: ke */
p = p->next = new_isakmp_data_payload(ISAKMP_PAYLOAD_KE,
ctx->dh_r_public, dh_getlen(ctx->dh_group));
/* payload: nonce_r */
p = p->next = new_isakmp_data_payload(ISAKMP_PAYLOAD_NONCE,
ctx->r_nonce, ctx->r_nonce_len);
/* payload: id_r */
p = p->next = new_isakmp_payload(ISAKMP_PAYLOAD_ID);
p->u.id.type = ISAKMP_IPSEC_ID_IPV4_ADDR;
p->u.id.protocol = IPPROTO_UDP;
p->u.id.port = IKE_PORT;
p->u.id.length = sizeof(in_addr_t);
mem_allocate(&p->u.id.data, p->u.id.length);
*((in_addr_t*)p->u.id.data) = inet_addr(ctx->cfg->gateway);
/* grab id_r */
mem_free(&ctx->r_id);
flatten_isakmp_payload(p, &ctx->r_id, &ctx->r_id_len, 1);
/*
* SKEYID = hmac(pre-shared-key, Nonce_I | Nonce_R)
* SKEYID_e = hmac(SKEYID, SKEYID_a | g^xy | Cookie_I | Cookie_R | 2)
* SKEYID_a = hmac(SKEYID, SKEYID_d | g^xy | Cookie_I | Cookie_R | 1)
* SKEYID_d = hmac(SKEYID, g^xy | Cookie_I | Cookie_R | 0)
*/
gcry_md_hd_t md_ctx;
/* generate skeyid */
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->ipsec_secret, strlen((char*)ctx->ipsec_secret));
gcry_md_write(md_ctx, ctx->i_nonce, ctx->i_nonce_len);
gcry_md_write(md_ctx, ctx->r_nonce, ctx->r_nonce_len);
gcry_md_final(md_ctx);
mem_allocate(&ctx->skeyid, ctx->md_len);
memcpy(ctx->skeyid, gcry_md_read(md_ctx, 0), ctx->md_len);
gcry_md_close(md_ctx);
/* generate skeyid_e */
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->skeyid, ctx->md_len);
gcry_md_write(md_ctx, ctx->dh_secret, dh_getlen(ctx->dh_group));
gcry_md_write(md_ctx, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(md_ctx, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_putc(md_ctx, 0);
gcry_md_final(md_ctx);
mem_allocate(&ctx->skeyid_d, ctx->md_len);
memcpy(ctx->skeyid_d, gcry_md_read(md_ctx, 0), ctx->md_len);
gcry_md_close(md_ctx);
/* generate skeyid_a */
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->skeyid, ctx->md_len);
gcry_md_write(md_ctx, ctx->skeyid_d, ctx->md_len);
gcry_md_write(md_ctx, ctx->dh_secret, dh_getlen(ctx->dh_group));
gcry_md_write(md_ctx, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(md_ctx, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_putc(md_ctx, 1);
gcry_md_final(md_ctx);
mem_allocate(&ctx->skeyid_a, ctx->md_len);
memcpy(ctx->skeyid_a, gcry_md_read(md_ctx, 0), ctx->md_len);
gcry_md_close(md_ctx);
/* generate skeyid_d */
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->skeyid, ctx->md_len);
gcry_md_write(md_ctx, ctx->skeyid_a, ctx->md_len);
gcry_md_write(md_ctx, ctx->dh_secret, dh_getlen(ctx->dh_group));
gcry_md_write(md_ctx, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(md_ctx, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_putc(md_ctx, 2);
gcry_md_final(md_ctx);
mem_allocate(&ctx->skeyid_e, ctx->md_len);
memcpy(ctx->skeyid_e, gcry_md_read(md_ctx, 0), ctx->md_len);
gcry_md_close(md_ctx);
/* encryption key */
mem_allocate(&ctx->key, ctx->key_len);
if (ctx->key_len > ctx->md_len) {
for (int i = 0; i * ctx->md_len < ctx->key_len; i++) {
gcry_md_open(&md_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(md_ctx, ctx->skeyid_e, ctx->md_len);
if (i == 0)
gcry_md_putc(md_ctx, 0);
else
gcry_md_write(md_ctx,
ctx->key + (i - 1) * ctx->md_len,
ctx->md_len);
gcry_md_final(md_ctx);
memcpy(ctx->key + i * ctx->md_len,
gcry_md_read(md_ctx, 0),
min(ctx->md_len, ctx->key_len - i * ctx->md_len));
gcry_md_close(md_ctx);
}
} else {
memcpy(ctx->key, ctx->skeyid_e, ctx->key_len);
}
/*
* HASH_I = prf(SKEYID, g^x | g^y | Cookie_I | Cookie_R | SA_I | ID_I )
* HASH_R = prf(SKEYID, g^y | g^x | Cookie_R | Cookie_I | SA_I | ID_R )
*/
/* generate i_hash */
gcry_md_hd_t i_hash_ctx;
gcry_md_open(&i_hash_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(i_hash_ctx, ctx->skeyid, ctx->md_len);
gcry_md_write(i_hash_ctx, ctx->dh_i_public, dh_getlen(ctx->dh_group));
gcry_md_write(i_hash_ctx, ctx->dh_r_public, dh_getlen(ctx->dh_group));
gcry_md_write(i_hash_ctx, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(i_hash_ctx, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(i_hash_ctx, ctx->i_sa + 4, ctx->i_sa_len - 4);
gcry_md_write(i_hash_ctx, ctx->i_id + 4, ctx->i_id_len - 4);
gcry_md_final(i_hash_ctx);
mem_allocate(&ctx->i_hash, ctx->md_len);
memcpy(ctx->i_hash, gcry_md_read(i_hash_ctx, 0), ctx->md_len);
gcry_md_close(i_hash_ctx);
/* generate r_hash */
gcry_md_hd_t r_hash_ctx;
gcry_md_open(&r_hash_ctx, ctx->md_algo, GCRY_MD_FLAG_HMAC);
gcry_md_setkey(r_hash_ctx, ctx->skeyid, ctx->md_len);
gcry_md_write(r_hash_ctx, ctx->dh_r_public, dh_getlen(ctx->dh_group));
gcry_md_write(r_hash_ctx, ctx->dh_i_public, dh_getlen(ctx->dh_group));
gcry_md_write(r_hash_ctx, ctx->r_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(r_hash_ctx, ctx->i_cookie, ISAKMP_COOKIE_LENGTH);
gcry_md_write(r_hash_ctx, ctx->i_sa + 4, ctx->i_sa_len - 4);
gcry_md_write(r_hash_ctx, ctx->r_id + 4, ctx->r_id_len - 4);
gcry_md_final(r_hash_ctx);
mem_allocate(&ctx->r_hash, ctx->md_len);
memcpy(ctx->r_hash, gcry_md_read(r_hash_ctx, 0), ctx->md_len);
gcry_md_close(r_hash_ctx);
/* payload: hash_r */
p = p->next = new_isakmp_data_payload(ISAKMP_PAYLOAD_HASH,
ctx->r_hash, ctx->md_len);
/* payload: Cisco Unity vendor id */
p = p->next = new_isakmp_data_payload(ISAKMP_PAYLOAD_VID,
unity_vid, sizeof(unity_vid));
/* payload: XAUTH vendor id */
p = p->next = new_isakmp_data_payload(ISAKMP_PAYLOAD_VID,
xauth_vid, sizeof(xauth_vid));
/* send response */
datagram *dgm = datagram_new(0);