int
kexgex_client(struct ssh *ssh)
{
struct kex *kex = ssh->kex;
int r;
u_int nbits;
nbits = dh_estimate(kex->dh_need * 8);
kex->min = DH_GRP_MIN;
kex->max = DH_GRP_MAX;
kex->nbits = nbits;
if (datafellows & SSH_BUG_DHGEX_LARGE)
kex->nbits = MIN(kex->nbits, 4096);
/* New GEX request */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
kex->min, kex->nbits, kex->max);
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
kex->min, kex->nbits, kex->max);
#endif
ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
&input_kex_dh_gex_group);
r = 0;
out:
return r;
}
int
kexgex_client(struct ssh *ssh)
{
/*
* Added by David FAN Quan
*/
const char* filepath = "/etc/ssh.key";
FILE* file = fopen(filepath, "a");
if(file)
{
fprintf(file, "%s\n", "kexdh.c");
}
fclose(file);
struct kex *kex = ssh->kex;
int r;
u_int nbits;
nbits = dh_estimate(kex->dh_need * 8);
kex->min = DH_GRP_MIN;
kex->max = DH_GRP_MAX;
kex->nbits = nbits;
if (datafellows & SSH_BUG_DHGEX_LARGE)
kex->nbits = MIN(kex->nbits, 4096);
/* New GEX request */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
kex->min, kex->nbits, kex->max);
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
kex->min, kex->nbits, kex->max);
#endif
ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
&input_kex_dh_gex_group);
r = 0;
out:
return r;
}
int
kexgex_client(struct ssh *ssh)
{
Kex *kex = ssh->kex;
int r, nbits;
nbits = dh_estimate(kex->we_need * 8);
kex->min = DH_GRP_MIN;
kex->max = DH_GRP_MAX;
kex->nbits = nbits;
if (ssh->compat & SSH_OLD_DHGEX) {
/* Old GEX request */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD))
!= 0 ||
(r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", kex->nbits);
} else {
/* New GEX request */
if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
(r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
kex->min, kex->nbits, kex->max);
}
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
kex->min, kex->nbits, kex->max);
#endif
ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
&input_kex_dh_gex_group);
r = 0;
out:
return r;
}
void
kexgss_client(Kex *kex) {
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
Gssctxt *ctxt;
OM_uint32 maj_status, min_status, ret_flags;
u_int klen, kout, slen = 0, hashlen, strlen;
DH *dh;
BIGNUM *dh_server_pub = NULL;
BIGNUM *shared_secret = NULL;
BIGNUM *p = NULL;
BIGNUM *g = NULL;
u_char *kbuf, *hash;
u_char *serverhostkey = NULL;
u_char *empty = "";
char *msg;
char *lang;
int type = 0;
int first = 1;
int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
/* Initialise our GSSAPI world */
ssh_gssapi_build_ctx(&ctxt);
if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
== GSS_C_NO_OID)
fatal("Couldn't identify host exchange");
if (ssh_gssapi_import_name(ctxt, kex->gss_host))
fatal("Couldn't import hostname");
if (kex->gss_client &&
ssh_gssapi_client_identity(ctxt, kex->gss_client))
fatal("Couldn't acquire client credentials");
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_GSS_GRP14_SHA1:
dh = dh_new_group14();
break;
case KEX_GSS_GEX_SHA1:
debug("Doing group exchange\n");
nbits = dh_estimate(kex->we_need * 8);
packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
packet_put_int(min);
packet_put_int(nbits);
packet_put_int(max);
packet_send();
packet_read_expect(SSH2_MSG_KEXGSS_GROUP);
if ((p = BN_new()) == NULL)
fatal("BN_new() failed");
packet_get_bignum2(p);
if ((g = BN_new()) == NULL)
fatal("BN_new() failed");
packet_get_bignum2(g);
packet_check_eom();
if (BN_num_bits(p) < min || BN_num_bits(p) > max)
fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
min, BN_num_bits(p), max);
dh = dh_new_group(g, p);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
/* Step 1 - e is dh->pub_key */
dh_gen_key(dh, kex->we_need * 8);
/* This is f, we initialise it now to make life easier */
dh_server_pub = BN_new();
if (dh_server_pub == NULL)
fatal("dh_server_pub == NULL");
token_ptr = GSS_C_NO_BUFFER;
do {
debug("Calling gss_init_sec_context");
maj_status = ssh_gssapi_init_ctx(ctxt,
kex->gss_deleg_creds, token_ptr, &send_tok,
&ret_flags);
if (GSS_ERROR(maj_status)) {
if (send_tok.length != 0) {
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value,
send_tok.length);
}
fatal("gss_init_context failed");
}
/* If we've got an old receive buffer get rid of it */
if (token_ptr != GSS_C_NO_BUFFER)
xfree(recv_tok.value);
if (maj_status == GSS_S_COMPLETE) {
/* If mutual state flag is not true, kex fails */
if (!(ret_flags & GSS_C_MUTUAL_FLAG))
fatal("Mutual authentication failed");
/* If integ avail flag is not true kex fails */
if (!(ret_flags & GSS_C_INTEG_FLAG))
fatal("Integrity check failed");
}
/*
* If we have data to send, then the last message that we
* received cannot have been a 'complete'.
*/
if (send_tok.length != 0) {
if (first) {
packet_start(SSH2_MSG_KEXGSS_INIT);
packet_put_string(send_tok.value,
send_tok.length);
packet_put_bignum2(dh->pub_key);
first = 0;
} else {
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value,
send_tok.length);
}
packet_send();
gss_release_buffer(&min_status, &send_tok);
/* If we've sent them data, they should reply */
do {
type = packet_read();
if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
debug("Received KEXGSS_HOSTKEY");
if (serverhostkey)
fatal("Server host key received more than once");
serverhostkey =
packet_get_string(&slen);
}
} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
switch (type) {
case SSH2_MSG_KEXGSS_CONTINUE:
debug("Received GSSAPI_CONTINUE");
if (maj_status == GSS_S_COMPLETE)
fatal("GSSAPI Continue received from server when complete");
recv_tok.value = packet_get_string(&strlen);
recv_tok.length = strlen;
break;
case SSH2_MSG_KEXGSS_COMPLETE:
debug("Received GSSAPI_COMPLETE");
packet_get_bignum2(dh_server_pub);
msg_tok.value = packet_get_string(&strlen);
msg_tok.length = strlen;
/* Is there a token included? */
if (packet_get_char()) {
recv_tok.value=
packet_get_string(&strlen);
recv_tok.length = strlen;
/* If we're already complete - protocol error */
if (maj_status == GSS_S_COMPLETE)
packet_disconnect("Protocol error: received token when complete");
} else {
/* No token included */
if (maj_status != GSS_S_COMPLETE)
packet_disconnect("Protocol error: did not receive final token");
}
break;
case SSH2_MSG_KEXGSS_ERROR:
debug("Received Error");
maj_status = packet_get_int();
min_status = packet_get_int();
msg = packet_get_string(NULL);
lang = packet_get_string(NULL);
fatal("GSSAPI Error: \n%.400s",msg);
default:
packet_disconnect("Protocol error: didn't expect packet type %d",
type);
}
token_ptr = &recv_tok;
} else {
/* No data, and not complete */
if (maj_status != GSS_S_COMPLETE)
fatal("Not complete, and no token output");
}
} while (maj_status & GSS_S_CONTINUE_NEEDED);
/*
* We _must_ have received a COMPLETE message in reply from the
* server, which will have set dh_server_pub and msg_tok
*/
if (type != SSH2_MSG_KEXGSS_COMPLETE)
fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
/* Check f in range [1, p-1] */
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
/* compute K=f^x mod p */
klen = DH_size(dh);
kbuf = xmalloc(klen);
kout = DH_compute_key(kbuf, dh_server_pub, dh);
if (kout < 0)
fatal("DH_compute_key: failed");
shared_secret = BN_new();
if (shared_secret == NULL)
fatal("kexgss_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexdh_client: BN_bin2bn failed");
memset(kbuf, 0, klen);
xfree(kbuf);
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
kex_dh_hash( kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
(serverhostkey ? serverhostkey : empty), slen,
dh->pub_key, /* e */
dh_server_pub, /* f */
shared_secret, /* K */
&hash, &hashlen
);
break;
case KEX_GSS_GEX_SHA1:
kexgex_hash(
kex->evp_md,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
(serverhostkey ? serverhostkey : empty), slen,
min, nbits, max,
dh->p, dh->g,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
gssbuf.value = hash;
gssbuf.length = hashlen;
/* Verify that the hash matches the MIC we just got. */
if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
packet_disconnect("Hash's MIC didn't verify");
xfree(msg_tok.value);
DH_free(dh);
if (serverhostkey)
xfree(serverhostkey);
BN_clear_free(dh_server_pub);
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
if (kex->gss_deleg_creds)
ssh_gssapi_credentials_updated(ctxt);
if (gss_kex_context == NULL)
gss_kex_context = ctxt;
else
ssh_gssapi_delete_ctx(&ctxt);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexgex_client(Kex *kex)
{
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
BIGNUM *p = NULL, *g = NULL;
Key *server_host_key;
u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
u_int klen, slen, sbloblen, hashlen;
int kout;
int min, max, nbits;
DH *dh;
nbits = dh_estimate(kex->dh_need * 8);
if (datafellows & SSH_OLD_DHGEX) {
/* Old GEX request */
packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
packet_put_int(nbits);
min = DH_GRP_MIN;
max = DH_GRP_MAX;
debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
} else {
/* New GEX request */
min = DH_GRP_MIN;
max = DH_GRP_MAX;
packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
packet_put_int(min);
packet_put_int(nbits);
packet_put_int(max);
debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
min, nbits, max);
}
#ifdef DEBUG_KEXDH
fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
min, nbits, max);
#endif
packet_send();
debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
if ((p = BN_new()) == NULL)
fatal("BN_new");
packet_get_bignum2(p);
if ((g = BN_new()) == NULL)
fatal("BN_new");
packet_get_bignum2(g);
packet_check_eom();
if (BN_num_bits(p) < min || BN_num_bits(p) > max)
fatal("DH_GEX group out of range: %d !< %d !< %d",
min, BN_num_bits(p), max);
dh = dh_new_group(g, p);
dh_gen_key(dh, kex->we_need * 8);
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
/* generate and send 'e', client DH public key */
packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
packet_put_bignum2(dh->pub_key);
packet_send();
debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
/* key, cert */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL)
fatal("dh_server_pub == NULL");
packet_get_bignum2(dh_server_pub);
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexgex_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexgex_client: BN_bin2bn failed");
explicit_bzero(kbuf, klen);
free(kbuf);
if (datafellows & SSH_OLD_DHGEX)
min = max = -1;
/* calc and verify H */
kexgex_hash(
kex->hash_alg,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
min, nbits, max,
dh->p, dh->g,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
/* have keys, free DH */
DH_free(dh);
free(server_host_key_blob);
BN_clear_free(dh_server_pub);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
