1264377Sdes/* $OpenBSD: kex.c,v 1.98 2014/02/02 03:44:31 djm Exp $ */ 2224638Sbrooks/* $FreeBSD$ */ 360573Skris/* 492555Sdes * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 560573Skris * 660573Skris * Redistribution and use in source and binary forms, with or without 760573Skris * modification, are permitted provided that the following conditions 860573Skris * are met: 960573Skris * 1. Redistributions of source code must retain the above copyright 1060573Skris * notice, this list of conditions and the following disclaimer. 1160573Skris * 2. Redistributions in binary form must reproduce the above copyright 1260573Skris * notice, this list of conditions and the following disclaimer in the 1360573Skris * documentation and/or other materials provided with the distribution. 1460573Skris * 1560573Skris * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 1660573Skris * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 1760573Skris * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 1860573Skris * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 1960573Skris * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 2060573Skris * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2160573Skris * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2260573Skris * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2360573Skris * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 2460573Skris * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 2560573Skris */ 2660573Skris 2760573Skris#include "includes.h" 2860573Skris 29162852Sdes#include <sys/param.h> 30162852Sdes 31162852Sdes#include <signal.h> 32162852Sdes#include <stdarg.h> 33162852Sdes#include <stdio.h> 34162852Sdes#include <stdlib.h> 35162852Sdes#include <string.h> 36162852Sdes 3776259Sgreen#include <openssl/crypto.h> 3876259Sgreen 39162852Sdes#include "xmalloc.h" 4060573Skris#include "ssh2.h" 4160573Skris#include "buffer.h" 4261209Skris#include "packet.h" 4360573Skris#include "compat.h" 4476259Sgreen#include "cipher.h" 45162852Sdes#include "key.h" 4660573Skris#include "kex.h" 4776259Sgreen#include "log.h" 4876259Sgreen#include "mac.h" 4976259Sgreen#include "match.h" 5076259Sgreen#include "dispatch.h" 5198675Sdes#include "monitor.h" 52204917Sdes#include "roaming.h" 53262566Sdes#include "digest.h" 5460573Skris 55162852Sdes#if OPENSSL_VERSION_NUMBER >= 0x00907000L 56162852Sdes# if defined(HAVE_EVP_SHA256) 57162852Sdes# define evp_ssh_sha256 EVP_sha256 58162852Sdes# else 59162852Sdesextern const EVP_MD *evp_ssh_sha256(void); 60162852Sdes# endif 61162852Sdes#endif 62162852Sdes 6392555Sdes/* prototype */ 6492555Sdesstatic void kex_kexinit_finish(Kex *); 6592555Sdesstatic void kex_choose_conf(Kex *); 6676259Sgreen 67255767Sdesstruct kexalg { 68255767Sdes char *name; 69255767Sdes int type; 70255767Sdes int ec_nid; 71262566Sdes int hash_alg; 72255767Sdes}; 73255767Sdesstatic const struct kexalg kexalgs[] = { 74262566Sdes { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 75262566Sdes { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 76262566Sdes { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 77255767Sdes#ifdef HAVE_EVP_SHA256 78262566Sdes { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 79255767Sdes#endif 80255767Sdes#ifdef OPENSSL_HAS_ECC 81262566Sdes { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 82262566Sdes NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 83262566Sdes { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 84262566Sdes SSH_DIGEST_SHA384 }, 85262566Sdes# ifdef OPENSSL_HAS_NISTP521 86262566Sdes { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 87262566Sdes SSH_DIGEST_SHA512 }, 88262566Sdes# endif 89255767Sdes#endif 90262566Sdes { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 91262566Sdes#ifdef HAVE_EVP_SHA256 92262566Sdes { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 93262566Sdes#endif 94262566Sdes { NULL, -1, -1, -1}, 95255767Sdes}; 96255767Sdes 97255767Sdeschar * 98262566Sdeskex_alg_list(char sep) 99255767Sdes{ 100255767Sdes char *ret = NULL; 101255767Sdes size_t nlen, rlen = 0; 102255767Sdes const struct kexalg *k; 103255767Sdes 104255767Sdes for (k = kexalgs; k->name != NULL; k++) { 105255767Sdes if (ret != NULL) 106262566Sdes ret[rlen++] = sep; 107255767Sdes nlen = strlen(k->name); 108255767Sdes ret = xrealloc(ret, 1, rlen + nlen + 2); 109255767Sdes memcpy(ret + rlen, k->name, nlen + 1); 110255767Sdes rlen += nlen; 111255767Sdes } 112255767Sdes return ret; 113255767Sdes} 114255767Sdes 115255767Sdesstatic const struct kexalg * 116255767Sdeskex_alg_by_name(const char *name) 117255767Sdes{ 118255767Sdes const struct kexalg *k; 119255767Sdes 120255767Sdes for (k = kexalgs; k->name != NULL; k++) { 121255767Sdes if (strcmp(k->name, name) == 0) 122255767Sdes return k; 123255767Sdes } 124255767Sdes return NULL; 125255767Sdes} 126255767Sdes 127221420Sdes/* Validate KEX method name list */ 128221420Sdesint 129221420Sdeskex_names_valid(const char *names) 130221420Sdes{ 131221420Sdes char *s, *cp, *p; 132221420Sdes 133221420Sdes if (names == NULL || strcmp(names, "") == 0) 134221420Sdes return 0; 135221420Sdes s = cp = xstrdup(names); 136221420Sdes for ((p = strsep(&cp, ",")); p && *p != '\0'; 137221420Sdes (p = strsep(&cp, ","))) { 138255767Sdes if (kex_alg_by_name(p) == NULL) { 139221420Sdes error("Unsupported KEX algorithm \"%.100s\"", p); 140255767Sdes free(s); 141221420Sdes return 0; 142221420Sdes } 143221420Sdes } 144221420Sdes debug3("kex names ok: [%s]", names); 145255767Sdes free(s); 146221420Sdes return 1; 147221420Sdes} 148221420Sdes 149240075Sdes/* put algorithm proposal into buffer. */ 150224638Sbrooks#ifndef NONE_CIPHER_ENABLED 15192555Sdesstatic void 152224638Sbrooks#else 153224638Sbrooks/* Also used in sshconnect2.c. */ 154224638Sbrooksvoid 155224638Sbrooks#endif 15676259Sgreenkex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 15760573Skris{ 158149749Sdes u_int i; 15976259Sgreen 16076259Sgreen buffer_clear(b); 16198675Sdes /* 16298675Sdes * add a dummy cookie, the cookie will be overwritten by 16398675Sdes * kex_send_kexinit(), each time a kexinit is set 16498675Sdes */ 16598675Sdes for (i = 0; i < KEX_COOKIE_LEN; i++) 16698675Sdes buffer_put_char(b, 0); 16760573Skris for (i = 0; i < PROPOSAL_MAX; i++) 16876259Sgreen buffer_put_cstring(b, proposal[i]); 16976259Sgreen buffer_put_char(b, 0); /* first_kex_packet_follows */ 17076259Sgreen buffer_put_int(b, 0); /* uint32 reserved */ 17160573Skris} 17260573Skris 17376259Sgreen/* parse buffer and return algorithm proposal */ 17492555Sdesstatic char ** 175113908Sdeskex_buf2prop(Buffer *raw, int *first_kex_follows) 17661209Skris{ 17776259Sgreen Buffer b; 178181111Sdes u_int i; 17976259Sgreen char **proposal; 18061209Skris 181162852Sdes proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 18261209Skris 18376259Sgreen buffer_init(&b); 18476259Sgreen buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 18561209Skris /* skip cookie */ 18661209Skris for (i = 0; i < KEX_COOKIE_LEN; i++) 18776259Sgreen buffer_get_char(&b); 18861209Skris /* extract kex init proposal strings */ 18961209Skris for (i = 0; i < PROPOSAL_MAX; i++) { 190221420Sdes proposal[i] = buffer_get_cstring(&b,NULL); 19176259Sgreen debug2("kex_parse_kexinit: %s", proposal[i]); 19261209Skris } 19376259Sgreen /* first kex follows / reserved */ 19476259Sgreen i = buffer_get_char(&b); 195113908Sdes if (first_kex_follows != NULL) 196113908Sdes *first_kex_follows = i; 19776259Sgreen debug2("kex_parse_kexinit: first_kex_follows %d ", i); 19876259Sgreen i = buffer_get_int(&b); 199181111Sdes debug2("kex_parse_kexinit: reserved %u ", i); 20076259Sgreen buffer_free(&b); 20176259Sgreen return proposal; 20261209Skris} 20361209Skris 20492555Sdesstatic void 20576259Sgreenkex_prop_free(char **proposal) 20660573Skris{ 207149749Sdes u_int i; 20860573Skris 20976259Sgreen for (i = 0; i < PROPOSAL_MAX; i++) 210255767Sdes free(proposal[i]); 211255767Sdes free(proposal); 21260573Skris} 21360573Skris 214181111Sdes/* ARGSUSED */ 21592555Sdesstatic void 21692555Sdeskex_protocol_error(int type, u_int32_t seq, void *ctxt) 21760573Skris{ 21892555Sdes error("Hm, kex protocol error: type %d seq %u", type, seq); 21960573Skris} 22060573Skris 22192555Sdesstatic void 22292555Sdeskex_reset_dispatch(void) 22369587Sgreen{ 22492555Sdes dispatch_range(SSH2_MSG_TRANSPORT_MIN, 22592555Sdes SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 22692555Sdes dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 22769587Sgreen} 22869587Sgreen 22976259Sgreenvoid 23076259Sgreenkex_finish(Kex *kex) 23169587Sgreen{ 23292555Sdes kex_reset_dispatch(); 23369587Sgreen 23476259Sgreen packet_start(SSH2_MSG_NEWKEYS); 23576259Sgreen packet_send(); 23676259Sgreen /* packet_write_wait(); */ 23776259Sgreen debug("SSH2_MSG_NEWKEYS sent"); 23869587Sgreen 239113908Sdes debug("expecting SSH2_MSG_NEWKEYS"); 24092555Sdes packet_read_expect(SSH2_MSG_NEWKEYS); 24192555Sdes packet_check_eom(); 24276259Sgreen debug("SSH2_MSG_NEWKEYS received"); 24369587Sgreen 24476259Sgreen kex->done = 1; 24576259Sgreen buffer_clear(&kex->peer); 24676259Sgreen /* buffer_clear(&kex->my); */ 24776259Sgreen kex->flags &= ~KEX_INIT_SENT; 248255767Sdes free(kex->name); 24976259Sgreen kex->name = NULL; 25069587Sgreen} 25169587Sgreen 25260573Skrisvoid 25376259Sgreenkex_send_kexinit(Kex *kex) 25460573Skris{ 255137015Sdes u_int32_t rnd = 0; 25698675Sdes u_char *cookie; 257149749Sdes u_int i; 25898675Sdes 25976259Sgreen if (kex == NULL) { 26076259Sgreen error("kex_send_kexinit: no kex, cannot rekey"); 26176259Sgreen return; 26260573Skris } 26376259Sgreen if (kex->flags & KEX_INIT_SENT) { 26476259Sgreen debug("KEX_INIT_SENT"); 26576259Sgreen return; 26676259Sgreen } 26776259Sgreen kex->done = 0; 26898675Sdes 26998675Sdes /* generate a random cookie */ 27098675Sdes if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 27198675Sdes fatal("kex_send_kexinit: kex proposal too short"); 27298675Sdes cookie = buffer_ptr(&kex->my); 27398675Sdes for (i = 0; i < KEX_COOKIE_LEN; i++) { 27498675Sdes if (i % 4 == 0) 275137015Sdes rnd = arc4random(); 276137015Sdes cookie[i] = rnd; 277137015Sdes rnd >>= 8; 27898675Sdes } 27976259Sgreen packet_start(SSH2_MSG_KEXINIT); 28076259Sgreen packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 28176259Sgreen packet_send(); 28276259Sgreen debug("SSH2_MSG_KEXINIT sent"); 28376259Sgreen kex->flags |= KEX_INIT_SENT; 28460573Skris} 28560573Skris 286181111Sdes/* ARGSUSED */ 28776259Sgreenvoid 28892555Sdeskex_input_kexinit(int type, u_int32_t seq, void *ctxt) 28960573Skris{ 29076259Sgreen char *ptr; 291149749Sdes u_int i, dlen; 29276259Sgreen Kex *kex = (Kex *)ctxt; 29360573Skris 29476259Sgreen debug("SSH2_MSG_KEXINIT received"); 29576259Sgreen if (kex == NULL) 29676259Sgreen fatal("kex_input_kexinit: no kex, cannot rekey"); 29760573Skris 29876259Sgreen ptr = packet_get_raw(&dlen); 29976259Sgreen buffer_append(&kex->peer, ptr, dlen); 30060573Skris 30176259Sgreen /* discard packet */ 30276259Sgreen for (i = 0; i < KEX_COOKIE_LEN; i++) 30376259Sgreen packet_get_char(); 30476259Sgreen for (i = 0; i < PROPOSAL_MAX; i++) 305255767Sdes free(packet_get_string(NULL)); 306248619Sdes /* 307248619Sdes * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 308248619Sdes * KEX method has the server move first, but a server might be using 309248619Sdes * a custom method or one that we otherwise don't support. We should 310248619Sdes * be prepared to remember first_kex_follows here so we can eat a 311248619Sdes * packet later. 312248619Sdes * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 313248619Sdes * for cases where the server *doesn't* go first. I guess we should 314248619Sdes * ignore it when it is set for these cases, which is what we do now. 315248619Sdes */ 316248619Sdes (void) packet_get_char(); /* first_kex_follows */ 317248619Sdes (void) packet_get_int(); /* reserved */ 31892555Sdes packet_check_eom(); 31960573Skris 32076259Sgreen kex_kexinit_finish(kex); 32160573Skris} 32260573Skris 32376259SgreenKex * 32476259Sgreenkex_setup(char *proposal[PROPOSAL_MAX]) 32569587Sgreen{ 32676259Sgreen Kex *kex; 32769587Sgreen 328162852Sdes kex = xcalloc(1, sizeof(*kex)); 32976259Sgreen buffer_init(&kex->peer); 33076259Sgreen buffer_init(&kex->my); 33176259Sgreen kex_prop2buf(&kex->my, proposal); 33276259Sgreen kex->done = 0; 33369587Sgreen 33476259Sgreen kex_send_kexinit(kex); /* we start */ 33592555Sdes kex_reset_dispatch(); 33669587Sgreen 33776259Sgreen return kex; 33869587Sgreen} 33969587Sgreen 34092555Sdesstatic void 34176259Sgreenkex_kexinit_finish(Kex *kex) 34260573Skris{ 34376259Sgreen if (!(kex->flags & KEX_INIT_SENT)) 34476259Sgreen kex_send_kexinit(kex); 34560573Skris 34676259Sgreen kex_choose_conf(kex); 34760573Skris 348113908Sdes if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 349113908Sdes kex->kex[kex->kex_type] != NULL) { 350113908Sdes (kex->kex[kex->kex_type])(kex); 351113908Sdes } else { 35276259Sgreen fatal("Unsupported key exchange %d", kex->kex_type); 35360573Skris } 35460573Skris} 35560573Skris 35692555Sdesstatic void 35760573Skrischoose_enc(Enc *enc, char *client, char *server) 35860573Skris{ 35976259Sgreen char *name = match_list(client, server, NULL); 36060573Skris if (name == NULL) 361181111Sdes fatal("no matching cipher found: client %s server %s", 362181111Sdes client, server); 36392555Sdes if ((enc->cipher = cipher_by_name(name)) == NULL) 36469587Sgreen fatal("matching cipher is not supported: %s", name); 36560573Skris enc->name = name; 36660573Skris enc->enabled = 0; 36760573Skris enc->iv = NULL; 368248619Sdes enc->iv_len = cipher_ivlen(enc->cipher); 36960573Skris enc->key = NULL; 37092555Sdes enc->key_len = cipher_keylen(enc->cipher); 37192555Sdes enc->block_size = cipher_blocksize(enc->cipher); 37260573Skris} 373162852Sdes 37492555Sdesstatic void 37560573Skrischoose_mac(Mac *mac, char *client, char *server) 37660573Skris{ 37776259Sgreen char *name = match_list(client, server, NULL); 37860573Skris if (name == NULL) 379181111Sdes fatal("no matching mac found: client %s server %s", 380181111Sdes client, server); 381181111Sdes if (mac_setup(mac, name) < 0) 38260573Skris fatal("unsupported mac %s", name); 38376259Sgreen /* truncate the key */ 38476259Sgreen if (datafellows & SSH_BUG_HMAC) 38576259Sgreen mac->key_len = 16; 38660573Skris mac->name = name; 38760573Skris mac->key = NULL; 38860573Skris mac->enabled = 0; 38960573Skris} 390162852Sdes 39192555Sdesstatic void 39260573Skrischoose_comp(Comp *comp, char *client, char *server) 39360573Skris{ 39476259Sgreen char *name = match_list(client, server, NULL); 39560573Skris if (name == NULL) 39660573Skris fatal("no matching comp found: client %s server %s", client, server); 397149749Sdes if (strcmp(name, "zlib@openssh.com") == 0) { 398149749Sdes comp->type = COMP_DELAYED; 399149749Sdes } else if (strcmp(name, "zlib") == 0) { 400149749Sdes comp->type = COMP_ZLIB; 40160573Skris } else if (strcmp(name, "none") == 0) { 402149749Sdes comp->type = COMP_NONE; 40360573Skris } else { 40460573Skris fatal("unsupported comp %s", name); 40560573Skris } 40660573Skris comp->name = name; 40760573Skris} 408162852Sdes 40992555Sdesstatic void 41060573Skrischoose_kex(Kex *k, char *client, char *server) 41160573Skris{ 412255767Sdes const struct kexalg *kexalg; 413255767Sdes 41476259Sgreen k->name = match_list(client, server, NULL); 41560573Skris if (k->name == NULL) 416181111Sdes fatal("Unable to negotiate a key exchange method"); 417255767Sdes if ((kexalg = kex_alg_by_name(k->name)) == NULL) 418255767Sdes fatal("unsupported kex alg %s", k->name); 419255767Sdes k->kex_type = kexalg->type; 420262566Sdes k->hash_alg = kexalg->hash_alg; 421255767Sdes k->ec_nid = kexalg->ec_nid; 42260573Skris} 423157016Sdes 42492555Sdesstatic void 42560573Skrischoose_hostkeyalg(Kex *k, char *client, char *server) 42660573Skris{ 42776259Sgreen char *hostkeyalg = match_list(client, server, NULL); 42876259Sgreen if (hostkeyalg == NULL) 42960573Skris fatal("no hostkey alg"); 43076259Sgreen k->hostkey_type = key_type_from_name(hostkeyalg); 43176259Sgreen if (k->hostkey_type == KEY_UNSPEC) 43276259Sgreen fatal("bad hostkey alg '%s'", hostkeyalg); 433255767Sdes free(hostkeyalg); 43460573Skris} 43560573Skris 436126274Sdesstatic int 437113908Sdesproposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 438113908Sdes{ 439113908Sdes static int check[] = { 440113908Sdes PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 441113908Sdes }; 442113908Sdes int *idx; 443113908Sdes char *p; 444113908Sdes 445113908Sdes for (idx = &check[0]; *idx != -1; idx++) { 446113908Sdes if ((p = strchr(my[*idx], ',')) != NULL) 447113908Sdes *p = '\0'; 448113908Sdes if ((p = strchr(peer[*idx], ',')) != NULL) 449113908Sdes *p = '\0'; 450113908Sdes if (strcmp(my[*idx], peer[*idx]) != 0) { 451113908Sdes debug2("proposal mismatch: my %s peer %s", 452113908Sdes my[*idx], peer[*idx]); 453113908Sdes return (0); 454113908Sdes } 455113908Sdes } 456113908Sdes debug2("proposals match"); 457113908Sdes return (1); 458113908Sdes} 459113908Sdes 46092555Sdesstatic void 46176259Sgreenkex_choose_conf(Kex *kex) 46260573Skris{ 46376259Sgreen Newkeys *newkeys; 46476259Sgreen char **my, **peer; 46576259Sgreen char **cprop, **sprop; 46676259Sgreen int nenc, nmac, ncomp; 467262566Sdes u_int mode, ctos, need, dh_need, authlen; 468113908Sdes int first_kex_follows, type; 469224638Sbrooks#ifdef NONE_CIPHER_ENABLED 470224638Sbrooks int auth_flag; 471224638Sbrooks#endif 47260573Skris 473113908Sdes my = kex_buf2prop(&kex->my, NULL); 474113908Sdes peer = kex_buf2prop(&kex->peer, &first_kex_follows); 47560573Skris 47676259Sgreen if (kex->server) { 47776259Sgreen cprop=peer; 47876259Sgreen sprop=my; 47976259Sgreen } else { 48076259Sgreen cprop=my; 48176259Sgreen sprop=peer; 48276259Sgreen } 48376259Sgreen 484204917Sdes /* Check whether server offers roaming */ 485204917Sdes if (!kex->server) { 486204917Sdes char *roaming; 487204917Sdes roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 488204917Sdes if (roaming) { 489204917Sdes kex->roaming = 1; 490255767Sdes free(roaming); 491204917Sdes } 492204917Sdes } 493204917Sdes 49476259Sgreen /* Algorithm Negotiation */ 495224638Sbrooks#ifdef NONE_CIPHER_ENABLED 496224638Sbrooks auth_flag = packet_get_authentication_state(); 497224638Sbrooks debug ("AUTH STATE is %d", auth_flag); 498224638Sbrooks#endif 49960573Skris for (mode = 0; mode < MODE_MAX; mode++) { 500162852Sdes newkeys = xcalloc(1, sizeof(*newkeys)); 50176259Sgreen kex->newkeys[mode] = newkeys; 502181111Sdes ctos = (!kex->server && mode == MODE_OUT) || 503181111Sdes (kex->server && mode == MODE_IN); 50460573Skris nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 50560573Skris nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 50660573Skris ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 507248619Sdes choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 508248619Sdes /* ignore mac for authenticated encryption */ 509248619Sdes authlen = cipher_authlen(newkeys->enc.cipher); 510248619Sdes if (authlen == 0) 511248619Sdes choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 51276259Sgreen choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 513224638Sbrooks#ifdef NONE_CIPHER_ENABLED 514224638Sbrooks debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); 515224638Sbrooks if (strcmp(newkeys->enc.name, "none") == 0) { 516231584Sed debug("Requesting NONE. Authflag is %d", auth_flag); 517224638Sbrooks if (auth_flag == 1) 518224638Sbrooks debug("None requested post authentication."); 519224638Sbrooks else 520224638Sbrooks fatal("Pre-authentication none cipher requests " 521224638Sbrooks "are not allowed."); 522231584Sed } 523224638Sbrooks#endif 52460573Skris debug("kex: %s %s %s %s", 52560573Skris ctos ? "client->server" : "server->client", 52676259Sgreen newkeys->enc.name, 527248619Sdes authlen == 0 ? newkeys->mac.name : "<implicit>", 52876259Sgreen newkeys->comp.name); 52960573Skris } 53076259Sgreen choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 53176259Sgreen choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 53260573Skris sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 533262566Sdes need = dh_need = 0; 53460573Skris for (mode = 0; mode < MODE_MAX; mode++) { 53576259Sgreen newkeys = kex->newkeys[mode]; 536262566Sdes need = MAX(need, newkeys->enc.key_len); 537262566Sdes need = MAX(need, newkeys->enc.block_size); 538262566Sdes need = MAX(need, newkeys->enc.iv_len); 539262566Sdes need = MAX(need, newkeys->mac.key_len); 540262566Sdes dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher)); 541262566Sdes dh_need = MAX(dh_need, newkeys->enc.block_size); 542262566Sdes dh_need = MAX(dh_need, newkeys->enc.iv_len); 543262566Sdes dh_need = MAX(dh_need, newkeys->mac.key_len); 54460573Skris } 54561209Skris /* XXX need runden? */ 54676259Sgreen kex->we_need = need; 547262566Sdes kex->dh_need = dh_need; 54876259Sgreen 549113908Sdes /* ignore the next message if the proposals do not match */ 550126274Sdes if (first_kex_follows && !proposals_match(my, peer) && 551149749Sdes !(datafellows & SSH_BUG_FIRSTKEX)) { 552113908Sdes type = packet_read(); 553113908Sdes debug2("skipping next packet (type %u)", type); 554113908Sdes } 555113908Sdes 55676259Sgreen kex_prop_free(my); 55776259Sgreen kex_prop_free(peer); 55860573Skris} 55960573Skris 56092555Sdesstatic u_char * 561157016Sdesderive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 562262566Sdes const u_char *shared_secret, u_int slen) 56360573Skris{ 56476259Sgreen Buffer b; 565262566Sdes struct ssh_digest_ctx *hashctx; 56676259Sgreen char c = id; 567149749Sdes u_int have; 568262566Sdes size_t mdsz; 569149749Sdes u_char *digest; 57060573Skris 571262566Sdes if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 572262566Sdes fatal("bad kex md size %zu", mdsz); 573162852Sdes digest = xmalloc(roundup(need, mdsz)); 574149749Sdes 57576259Sgreen buffer_init(&b); 576262566Sdes buffer_append(&b, shared_secret, slen); 57776259Sgreen 57876259Sgreen /* K1 = HASH(K || H || "A" || session_id) */ 579262566Sdes if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 580262566Sdes fatal("%s: ssh_digest_start failed", __func__); 581262566Sdes if (ssh_digest_update_buffer(hashctx, &b) != 0 || 582262566Sdes ssh_digest_update(hashctx, hash, hashlen) != 0 || 583262566Sdes ssh_digest_update(hashctx, &c, 1) != 0 || 584262566Sdes ssh_digest_update(hashctx, kex->session_id, 585262566Sdes kex->session_id_len) != 0) 586262566Sdes fatal("%s: ssh_digest_update failed", __func__); 587262566Sdes if (ssh_digest_final(hashctx, digest, mdsz) != 0) 588262566Sdes fatal("%s: ssh_digest_final failed", __func__); 589262566Sdes ssh_digest_free(hashctx); 59076259Sgreen 59176259Sgreen /* 59276259Sgreen * expand key: 59376259Sgreen * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 59476259Sgreen * Key = K1 || K2 || ... || Kn 59576259Sgreen */ 59676259Sgreen for (have = mdsz; need > have; have += mdsz) { 597262566Sdes if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 598262566Sdes fatal("%s: ssh_digest_start failed", __func__); 599262566Sdes if (ssh_digest_update_buffer(hashctx, &b) != 0 || 600262566Sdes ssh_digest_update(hashctx, hash, hashlen) != 0 || 601262566Sdes ssh_digest_update(hashctx, digest, have) != 0) 602262566Sdes fatal("%s: ssh_digest_update failed", __func__); 603262566Sdes if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 604262566Sdes fatal("%s: ssh_digest_final failed", __func__); 605262566Sdes ssh_digest_free(hashctx); 60676259Sgreen } 60776259Sgreen buffer_free(&b); 60876259Sgreen#ifdef DEBUG_KEX 60976259Sgreen fprintf(stderr, "key '%c'== ", c); 61076259Sgreen dump_digest("key", digest, need); 61176259Sgreen#endif 61276259Sgreen return digest; 61376259Sgreen} 61476259Sgreen 61576259SgreenNewkeys *current_keys[MODE_MAX]; 61676259Sgreen 61776259Sgreen#define NKEYS 6 61876259Sgreenvoid 619262566Sdeskex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 620262566Sdes const u_char *shared_secret, u_int slen) 62176259Sgreen{ 62276259Sgreen u_char *keys[NKEYS]; 623149749Sdes u_int i, mode, ctos; 62476259Sgreen 625157016Sdes for (i = 0; i < NKEYS; i++) { 626157016Sdes keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 627262566Sdes shared_secret, slen); 628157016Sdes } 62960573Skris 630113908Sdes debug2("kex_derive_keys"); 63160573Skris for (mode = 0; mode < MODE_MAX; mode++) { 63276259Sgreen current_keys[mode] = kex->newkeys[mode]; 63376259Sgreen kex->newkeys[mode] = NULL; 634162852Sdes ctos = (!kex->server && mode == MODE_OUT) || 635162852Sdes (kex->server && mode == MODE_IN); 63676259Sgreen current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 63776259Sgreen current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 63876259Sgreen current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 63960573Skris } 64060573Skris} 64176259Sgreen 642262566Sdesvoid 643262566Sdeskex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret) 644262566Sdes{ 645262566Sdes Buffer shared_secret; 646262566Sdes 647262566Sdes buffer_init(&shared_secret); 648262566Sdes buffer_put_bignum2(&shared_secret, secret); 649262566Sdes kex_derive_keys(kex, hash, hashlen, 650262566Sdes buffer_ptr(&shared_secret), buffer_len(&shared_secret)); 651262566Sdes buffer_free(&shared_secret); 652262566Sdes} 653262566Sdes 65476259SgreenNewkeys * 65576259Sgreenkex_get_newkeys(int mode) 65676259Sgreen{ 65776259Sgreen Newkeys *ret; 65876259Sgreen 65976259Sgreen ret = current_keys[mode]; 66076259Sgreen current_keys[mode] = NULL; 66176259Sgreen return ret; 66276259Sgreen} 66376259Sgreen 664137015Sdesvoid 665137015Sdesderive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 666137015Sdes u_int8_t cookie[8], u_int8_t id[16]) 667137015Sdes{ 668262566Sdes u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 669137015Sdes int len; 670262566Sdes struct ssh_digest_ctx *hashctx; 671137015Sdes 672262566Sdes if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 673262566Sdes fatal("%s: ssh_digest_start", __func__); 674137015Sdes 675137015Sdes len = BN_num_bytes(host_modulus); 676149749Sdes if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 677137015Sdes fatal("%s: bad host modulus (len %d)", __func__, len); 678137015Sdes BN_bn2bin(host_modulus, nbuf); 679262566Sdes if (ssh_digest_update(hashctx, nbuf, len) != 0) 680262566Sdes fatal("%s: ssh_digest_update failed", __func__); 681137015Sdes 682137015Sdes len = BN_num_bytes(server_modulus); 683149749Sdes if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 684137015Sdes fatal("%s: bad server modulus (len %d)", __func__, len); 685137015Sdes BN_bn2bin(server_modulus, nbuf); 686262566Sdes if (ssh_digest_update(hashctx, nbuf, len) != 0 || 687262566Sdes ssh_digest_update(hashctx, cookie, 8) != 0) 688262566Sdes fatal("%s: ssh_digest_update failed", __func__); 689262566Sdes if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 690262566Sdes fatal("%s: ssh_digest_final failed", __func__); 691262566Sdes memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 692137015Sdes 693264377Sdes explicit_bzero(nbuf, sizeof(nbuf)); 694264377Sdes explicit_bzero(obuf, sizeof(obuf)); 695137015Sdes} 696137015Sdes 697221420Sdes#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 69876259Sgreenvoid 69976259Sgreendump_digest(char *msg, u_char *digest, int len) 70076259Sgreen{ 701221420Sdes int i; 70276259Sgreen 70376259Sgreen fprintf(stderr, "%s\n", msg); 704181111Sdes for (i = 0; i < len; i++) { 70576259Sgreen fprintf(stderr, "%02x", digest[i]); 70676259Sgreen if (i%32 == 31) 70776259Sgreen fprintf(stderr, "\n"); 70876259Sgreen else if (i%8 == 7) 70976259Sgreen fprintf(stderr, " "); 71076259Sgreen } 71176259Sgreen fprintf(stderr, "\n"); 71276259Sgreen} 71376259Sgreen#endif 714