Annotation of src/usr.bin/ssh/kexc25519s.c, Revision 1.6
1.6 ! markus 1: /* $OpenBSD: kexc25519s.c,v 1.5 2015/01/19 19:52:16 markus Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2001 Markus Friedl. All rights reserved.
4: * Copyright (c) 2010 Damien Miller. All rights reserved.
5: * Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
6: *
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
27: #include <sys/types.h>
28: #include <string.h>
29: #include <signal.h>
30:
1.6 ! markus 31: #include "sshkey.h"
1.1 markus 32: #include "cipher.h"
1.6 ! markus 33: #include "digest.h"
1.1 markus 34: #include "kex.h"
35: #include "log.h"
36: #include "packet.h"
37: #include "ssh2.h"
1.6 ! markus 38: #include "sshbuf.h"
! 39: #include "ssherr.h"
1.1 markus 40:
1.6 ! markus 41: static int input_kex_c25519_init(int, u_int32_t, void *);
! 42:
! 43: int
! 44: kexc25519_server(struct ssh *ssh)
! 45: {
! 46: debug("expecting SSH2_MSG_KEX_ECDH_INIT");
! 47: ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_c25519_init);
! 48: return 0;
! 49: }
! 50:
! 51: static int
! 52: input_kex_c25519_init(int type, u_int32_t seq, void *ctxt)
1.1 markus 53: {
1.6 ! markus 54: struct ssh *ssh = ctxt;
! 55: struct kex *kex = ssh->kex;
! 56: struct sshkey *server_host_private, *server_host_public;
! 57: struct sshbuf *shared_secret = NULL;
1.1 markus 58: u_char *server_host_key_blob = NULL, *signature = NULL;
59: u_char server_key[CURVE25519_SIZE];
60: u_char *client_pubkey = NULL;
61: u_char server_pubkey[CURVE25519_SIZE];
1.6 ! markus 62: u_char hash[SSH_DIGEST_MAX_LENGTH];
! 63: size_t slen, pklen, sbloblen, hashlen;
! 64: int r;
1.1 markus 65:
66: /* generate private key */
67: kexc25519_keygen(server_key, server_pubkey);
68: #ifdef DEBUG_KEXECDH
69: dump_digest("server private key:", server_key, sizeof(server_key));
70: #endif
71: if (kex->load_host_public_key == NULL ||
1.6 ! markus 72: kex->load_host_private_key == NULL) {
! 73: r = SSH_ERR_INVALID_ARGUMENT;
! 74: goto out;
! 75: }
! 76: if ((server_host_public = kex->load_host_public_key(kex->hostkey_type,
! 77: ssh)) == NULL ||
! 78: (server_host_private = kex->load_host_private_key(kex->hostkey_type,
! 79: ssh)) == NULL) {
! 80: r = SSH_ERR_NO_HOSTKEY_LOADED;
! 81: goto out;
! 82: }
1.1 markus 83:
1.6 ! markus 84: if ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 ||
! 85: (r = sshpkt_get_end(ssh)) != 0)
! 86: goto out;
! 87: if (pklen != CURVE25519_SIZE) {
! 88: r = SSH_ERR_SIGNATURE_INVALID;
! 89: goto out;
! 90: }
1.1 markus 91: #ifdef DEBUG_KEXECDH
92: dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
93: #endif
94:
1.6 ! markus 95: if ((shared_secret = sshbuf_new()) == NULL) {
! 96: r = SSH_ERR_ALLOC_FAIL;
! 97: goto out;
! 98: }
! 99: if ((r = kexc25519_shared_key(server_key, client_pubkey,
! 100: shared_secret)) < 0)
! 101: goto out;
1.1 markus 102:
103: /* calc H */
1.6 ! markus 104: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
! 105: &sbloblen)) != 0)
! 106: goto out;
! 107: hashlen = sizeof(hash);
! 108: if ((r = kex_c25519_hash(
1.3 djm 109: kex->hash_alg,
1.1 markus 110: kex->client_version_string,
111: kex->server_version_string,
1.6 ! markus 112: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
! 113: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
1.1 markus 114: server_host_key_blob, sbloblen,
115: client_pubkey,
116: server_pubkey,
1.6 ! markus 117: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
! 118: hash, &hashlen)) < 0)
! 119: goto out;
1.1 markus 120:
121: /* save session id := H */
122: if (kex->session_id == NULL) {
123: kex->session_id_len = hashlen;
1.6 ! markus 124: kex->session_id = malloc(kex->session_id_len);
! 125: if (kex->session_id == NULL) {
! 126: r = SSH_ERR_ALLOC_FAIL;
! 127: goto out;
! 128: }
1.1 markus 129: memcpy(kex->session_id, hash, kex->session_id_len);
130: }
131:
132: /* sign H */
1.6 ! markus 133: if ((r = kex->sign(server_host_private, server_host_public,
! 134: &signature, &slen, hash, hashlen, ssh->compat)) < 0)
! 135: goto out;
1.1 markus 136:
137: /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
1.6 ! markus 138: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
! 139: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
! 140: (r = sshpkt_put_string(ssh, server_pubkey, sizeof(server_pubkey))) != 0 ||
! 141: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
! 142: (r = sshpkt_send(ssh)) != 0)
! 143: goto out;
! 144:
! 145: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
! 146: r = kex_send_newkeys(ssh);
! 147: out:
! 148: explicit_bzero(hash, sizeof(hash));
! 149: explicit_bzero(server_key, sizeof(server_key));
! 150: free(server_host_key_blob);
1.1 markus 151: free(signature);
152: free(client_pubkey);
1.6 ! markus 153: sshbuf_free(shared_secret);
! 154: return r;
1.1 markus 155: }