summaryrefslogtreecommitdiff
path: root/kexgexc.c
diff options
context:
space:
mode:
Diffstat (limited to 'kexgexc.c')
-rw-r--r--kexgexc.c186
1 files changed, 63 insertions, 123 deletions
diff --git a/kexgexc.c b/kexgexc.c
index e8e059a8..323a659b 100644
--- a/kexgexc.c
+++ b/kexgexc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexc.c,v 1.20 2015/01/26 06:10:03 djm Exp $ */
+/* $OpenBSD: kexgexc.c,v 1.35 2019/11/25 00:51:37 djm Exp $ */
/*
* Copyright (c) 2000 Niels Provos. All rights reserved.
* Copyright (c) 2001 Markus Friedl. All rights reserved.
@@ -37,6 +37,8 @@
#include <string.h>
#include <signal.h>
+#include "openbsd-compat/openssl-compat.h"
+
#include "sshkey.h"
#include "cipher.h"
#include "digest.h"
@@ -49,9 +51,10 @@
#include "dispatch.h"
#include "ssherr.h"
#include "sshbuf.h"
+#include "misc.h"
-static int input_kex_dh_gex_group(int, u_int32_t, void *);
-static int input_kex_dh_gex_reply(int, u_int32_t, void *);
+static int input_kex_dh_gex_group(int, u_int32_t, struct ssh *);
+static int input_kex_dh_gex_reply(int, u_int32_t, struct ssh *);
int
kexgex_client(struct ssh *ssh)
@@ -65,25 +68,17 @@ kexgex_client(struct ssh *ssh)
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);
- }
+ if (datafellows & SSH_BUG_DHGEX_LARGE)
+ kex->nbits = MINIMUM(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);
@@ -96,22 +91,17 @@ kexgex_client(struct ssh *ssh)
}
static int
-input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt)
+input_kex_dh_gex_group(int type, u_int32_t seq, struct ssh *ssh)
{
- struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
BIGNUM *p = NULL, *g = NULL;
+ const BIGNUM *pub_key;
int r, bits;
debug("got SSH2_MSG_KEX_DH_GEX_GROUP");
- if ((p = BN_new()) == NULL ||
- (g = BN_new()) == NULL) {
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- if ((r = sshpkt_get_bignum2(ssh, p)) != 0 ||
- (r = sshpkt_get_bignum2(ssh, g)) != 0 ||
+ if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 ||
+ (r = sshpkt_get_bignum2(ssh, &g)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
if ((bits = BN_num_bits(p)) < 0 ||
@@ -126,153 +116,103 @@ input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt)
p = g = NULL; /* belong to kex->dh now */
/* generate and send 'e', client DH public key */
- if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 ||
- (r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 ||
- (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||
+ if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
+ goto out;
+ DH_get0_key(kex->dh, &pub_key, NULL);
+ if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 ||
+ (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
goto out;
debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, kex->dh);
fprintf(stderr, "pub= ");
- BN_print_fp(stderr, kex->dh->pub_key);
+ BN_print_fp(stderr, pub_key);
fprintf(stderr, "\n");
#endif
ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP, NULL);
ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REPLY, &input_kex_dh_gex_reply);
r = 0;
out:
- if (p)
- BN_clear_free(p);
- if (g)
- BN_clear_free(g);
+ BN_clear_free(p);
+ BN_clear_free(g);
return r;
}
static int
-input_kex_dh_gex_reply(int type, u_int32_t seq, void *ctxt)
+input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
{
- struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
- BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
+ BIGNUM *dh_server_pub = NULL;
+ const BIGNUM *pub_key, *dh_p, *dh_g;
+ struct sshbuf *shared_secret = NULL;
+ struct sshbuf *tmp = NULL, *server_host_key_blob = NULL;
struct sshkey *server_host_key = NULL;
- u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
+ u_char *signature = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
- size_t klen = 0, slen, sbloblen, hashlen;
- int kout, r;
+ size_t slen, hashlen;
+ int r;
debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
- if (kex->verify_host_key == NULL) {
- r = SSH_ERR_INVALID_ARGUMENT;
- goto out;
- }
/* key, cert */
- if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
- &sbloblen)) != 0 ||
- (r = sshkey_from_blob(server_host_key_blob, sbloblen,
- &server_host_key)) != 0)
+ if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
goto out;
- if (server_host_key->type != kex->hostkey_type) {
- r = SSH_ERR_KEY_TYPE_MISMATCH;
- goto out;
- }
- if (server_host_key->type != kex->hostkey_type ||
- (kex->hostkey_type == KEY_ECDSA &&
- server_host_key->ecdsa_nid != kex->hostkey_nid)) {
- r = SSH_ERR_KEY_TYPE_MISMATCH;
- goto out;
- }
- if (kex->verify_host_key(server_host_key, ssh) == -1) {
- r = SSH_ERR_SIGNATURE_INVALID;
- goto out;
- }
- /* DH parameter f, server public DH key */
- if ((dh_server_pub = BN_new()) == NULL) {
+ /* sshkey_fromb() consumes its buffer, so make a copy */
+ if ((tmp = sshbuf_fromb(server_host_key_blob)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
- /* signed H */
- if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
+ if ((r = sshkey_fromb(tmp, &server_host_key)) != 0 ||
+ (r = kex_verify_host_key(ssh, server_host_key)) != 0)
+ goto out;
+ /* DH parameter f, server public DH key, signed H */
+ if ((r = sshpkt_get_bignum2(ssh, &dh_server_pub)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
-#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
- if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
- sshpkt_disconnect(ssh, "bad server public DH value");
- r = SSH_ERR_MESSAGE_INCOMPLETE;
- goto out;
- }
-
- klen = DH_size(kex->dh);
- if ((kbuf = malloc(klen)) == NULL ||
- (shared_secret = BN_new()) == NULL) {
+ if ((shared_secret = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
- if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
- BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
- r = SSH_ERR_LIBCRYPTO_ERROR;
+ if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
goto out;
- }
-#ifdef DEBUG_KEXDH
- dump_digest("shared secret", kbuf, kout);
-#endif
if (ssh->compat & SSH_OLD_DHGEX)
kex->min = kex->max = -1;
/* calc and verify H */
+ DH_get0_key(kex->dh, &pub_key, NULL);
+ DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
hashlen = sizeof(hash);
if ((r = kexgex_hash(
kex->hash_alg,
- kex->client_version_string,
- kex->server_version_string,
- sshbuf_ptr(kex->my), sshbuf_len(kex->my),
- sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
- server_host_key_blob, sbloblen,
+ kex->client_version,
+ kex->server_version,
+ kex->my,
+ kex->peer,
+ server_host_key_blob,
kex->min, kex->nbits, kex->max,
- kex->dh->p, kex->dh->g,
- kex->dh->pub_key,
+ dh_p, dh_g,
+ pub_key,
dh_server_pub,
- shared_secret,
+ sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
hash, &hashlen)) != 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash,
- hashlen, ssh->compat)) != 0)
+ hashlen, kex->hostkey_alg, ssh->compat, NULL)) != 0)
goto out;
- /* save session id */
- if (kex->session_id == NULL) {
- kex->session_id_len = hashlen;
- kex->session_id = malloc(kex->session_id_len);
- if (kex->session_id == NULL) {
- r = SSH_ERR_ALLOC_FAIL;
- goto out;
- }
- memcpy(kex->session_id, hash, kex->session_id_len);
- }
-
- if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
+ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
DH_free(kex->dh);
kex->dh = NULL;
- if (dh_server_pub)
- BN_clear_free(dh_server_pub);
- if (kbuf) {
- explicit_bzero(kbuf, klen);
- free(kbuf);
- }
- if (shared_secret)
- BN_clear_free(shared_secret);
+ BN_clear_free(dh_server_pub);
+ sshbuf_free(shared_secret);
sshkey_free(server_host_key);
- free(server_host_key_blob);
+ sshbuf_free(tmp);
+ sshbuf_free(server_host_key_blob);
free(signature);
return r;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-03 02:18:56 +0000