Annotation of src/usr.bin/ssh/kexc25519c.c, Revision 1.6
1.6 ! markus 1: /* $OpenBSD: kexc25519c.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: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: *
16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26: */
27:
28: #include <sys/types.h>
29:
30: #include <stdio.h>
31: #include <string.h>
32: #include <signal.h>
33:
1.6 ! markus 34: #include "sshkey.h"
1.1 markus 35: #include "cipher.h"
36: #include "kex.h"
37: #include "log.h"
38: #include "packet.h"
39: #include "ssh2.h"
1.6 ! markus 40: #include "sshbuf.h"
! 41: #include "digest.h"
! 42: #include "ssherr.h"
1.1 markus 43:
1.6 ! markus 44: static int
! 45: input_kex_c25519_reply(int type, u_int32_t seq, void *ctxt);
! 46:
! 47: int
! 48: kexc25519_client(struct ssh *ssh)
1.1 markus 49: {
1.6 ! markus 50: struct kex *kex = ssh->kex;
! 51: int r;
1.1 markus 52:
1.6 ! markus 53: kexc25519_keygen(kex->c25519_client_key, kex->c25519_client_pubkey);
1.1 markus 54: #ifdef DEBUG_KEXECDH
1.6 ! markus 55: dump_digest("client private key:", kex->c25519_client_key,
! 56: sizeof(kex->c25519_client_key));
1.1 markus 57: #endif
1.6 ! markus 58: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 ||
! 59: (r = sshpkt_put_string(ssh, kex->c25519_client_pubkey,
! 60: sizeof(kex->c25519_client_pubkey))) != 0 ||
! 61: (r = sshpkt_send(ssh)) != 0)
! 62: return r;
1.1 markus 63:
64: debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
1.6 ! markus 65: ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_c25519_reply);
! 66: return 0;
! 67: }
! 68:
! 69: static int
! 70: input_kex_c25519_reply(int type, u_int32_t seq, void *ctxt)
! 71: {
! 72: struct ssh *ssh = ctxt;
! 73: struct kex *kex = ssh->kex;
! 74: struct sshkey *server_host_key = NULL;
! 75: struct sshbuf *shared_secret = NULL;
! 76: u_char *server_pubkey = NULL;
! 77: u_char *server_host_key_blob = NULL, *signature = NULL;
! 78: u_char hash[SSH_DIGEST_MAX_LENGTH];
! 79: size_t slen, pklen, sbloblen, hashlen;
! 80: int r;
! 81:
! 82: if (kex->verify_host_key == NULL) {
! 83: r = SSH_ERR_INVALID_ARGUMENT;
! 84: goto out;
! 85: }
1.1 markus 86:
87: /* hostkey */
1.6 ! markus 88: if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
! 89: &sbloblen)) != 0 ||
! 90: (r = sshkey_from_blob(server_host_key_blob, sbloblen,
! 91: &server_host_key)) != 0)
! 92: goto out;
! 93: if (server_host_key->type != kex->hostkey_type) {
! 94: r = SSH_ERR_KEY_TYPE_MISMATCH;
! 95: goto out;
! 96: }
! 97: if (kex->verify_host_key(server_host_key, ssh) == -1) {
! 98: r = SSH_ERR_SIGNATURE_INVALID;
! 99: goto out;
! 100: }
1.1 markus 101:
102: /* Q_S, server public key */
1.6 ! markus 103: /* signed H */
! 104: if ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 ||
! 105: (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
! 106: (r = sshpkt_get_end(ssh)) != 0)
! 107: goto out;
! 108: if (pklen != CURVE25519_SIZE) {
! 109: r = SSH_ERR_SIGNATURE_INVALID;
! 110: goto out;
! 111: }
1.1 markus 112:
113: #ifdef DEBUG_KEXECDH
114: dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
115: #endif
116:
1.6 ! markus 117: if ((shared_secret = sshbuf_new()) == NULL) {
! 118: r = SSH_ERR_ALLOC_FAIL;
! 119: goto out;
! 120: }
! 121: if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey,
! 122: shared_secret)) < 0)
! 123: goto out;
1.1 markus 124:
125: /* calc and verify H */
1.6 ! markus 126: hashlen = sizeof(hash);
! 127: if ((r = kex_c25519_hash(
1.3 djm 128: kex->hash_alg,
1.1 markus 129: kex->client_version_string,
130: kex->server_version_string,
1.6 ! markus 131: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
! 132: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
1.1 markus 133: server_host_key_blob, sbloblen,
1.6 ! markus 134: kex->c25519_client_pubkey,
1.1 markus 135: server_pubkey,
1.6 ! markus 136: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
! 137: hash, &hashlen)) < 0)
! 138: goto out;
! 139:
! 140: if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
! 141: ssh->compat)) != 0)
! 142: goto out;
1.1 markus 143:
144: /* save session id */
145: if (kex->session_id == NULL) {
146: kex->session_id_len = hashlen;
1.6 ! markus 147: kex->session_id = malloc(kex->session_id_len);
! 148: if (kex->session_id == NULL) {
! 149: r = SSH_ERR_ALLOC_FAIL;
! 150: goto out;
! 151: }
1.1 markus 152: memcpy(kex->session_id, hash, kex->session_id_len);
153: }
1.6 ! markus 154:
! 155: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
! 156: r = kex_send_newkeys(ssh);
! 157: out:
! 158: explicit_bzero(hash, sizeof(hash));
! 159: explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
! 160: free(server_host_key_blob);
! 161: free(server_pubkey);
! 162: free(signature);
! 163: sshkey_free(server_host_key);
! 164: sshbuf_free(shared_secret);
! 165: return r;
1.1 markus 166: }
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