/*
- * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.28 2001/04/04 09:48:34 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.52 2002/11/21 22:45:31 markus Exp $");
#include <openssl/crypto.h>
#include "mac.h"
#include "match.h"
#include "dispatch.h"
+#include "monitor.h"
#define KEX_COOKIE_LEN 16
-void kex_kexinit_finish(Kex *kex);
-void kex_choose_conf(Kex *k);
+/* Use privilege separation for sshd */
+int use_privsep;
+struct monitor *pmonitor;
+
+
+/* prototype */
+static void kex_kexinit_finish(Kex *);
+static void kex_choose_conf(Kex *);
/* put algorithm proposal into buffer */
-void
+static void
kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
- u_int32_t rand = 0;
int i;
buffer_clear(b);
- for (i = 0; i < KEX_COOKIE_LEN; i++) {
- if (i % 4 == 0)
- rand = arc4random();
- buffer_put_char(b, rand & 0xff);
- rand >>= 8;
- }
+ /*
+ * add a dummy cookie, the cookie will be overwritten by
+ * kex_send_kexinit(), each time a kexinit is set
+ */
+ for (i = 0; i < KEX_COOKIE_LEN; i++)
+ buffer_put_char(b, 0);
for (i = 0; i < PROPOSAL_MAX; i++)
buffer_put_cstring(b, proposal[i]);
buffer_put_char(b, 0); /* first_kex_packet_follows */
}
/* parse buffer and return algorithm proposal */
-char **
+static char **
kex_buf2prop(Buffer *raw)
{
Buffer b;
return proposal;
}
-void
+static void
kex_prop_free(char **proposal)
{
int i;
xfree(proposal);
}
-void
-kex_protocol_error(int type, int plen, void *ctxt)
+static void
+kex_protocol_error(int type, u_int32_t seq, void *ctxt)
{
- error("Hm, kex protocol error: type %d plen %d", type, plen);
+ error("Hm, kex protocol error: type %d seq %u", type, seq);
+}
+
+static void
+kex_reset_dispatch(void)
+{
+ dispatch_range(SSH2_MSG_TRANSPORT_MIN,
+ SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
+ dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}
void
kex_finish(Kex *kex)
{
- int i, plen;
+ kex_reset_dispatch();
packet_start(SSH2_MSG_NEWKEYS);
packet_send();
/* packet_write_wait(); */
debug("SSH2_MSG_NEWKEYS sent");
- debug("waiting for SSH2_MSG_NEWKEYS");
- packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
+ debug("expecting SSH2_MSG_NEWKEYS");
+ packet_read_expect(SSH2_MSG_NEWKEYS);
+ packet_check_eom();
debug("SSH2_MSG_NEWKEYS received");
- kex->newkeys = 1;
- for (i = 30; i <= 49; i++)
- dispatch_set(i, &kex_protocol_error);
+
+ kex->done = 1;
buffer_clear(&kex->peer);
/* buffer_clear(&kex->my); */
kex->flags &= ~KEX_INIT_SENT;
+ xfree(kex->name);
+ kex->name = NULL;
}
void
kex_send_kexinit(Kex *kex)
{
+ u_int32_t rand = 0;
+ u_char *cookie;
+ int i;
+
+ if (kex == NULL) {
+ error("kex_send_kexinit: no kex, cannot rekey");
+ return;
+ }
if (kex->flags & KEX_INIT_SENT) {
debug("KEX_INIT_SENT");
return;
}
+ kex->done = 0;
+
+ /* generate a random cookie */
+ if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
+ fatal("kex_send_kexinit: kex proposal too short");
+ cookie = buffer_ptr(&kex->my);
+ for (i = 0; i < KEX_COOKIE_LEN; i++) {
+ if (i % 4 == 0)
+ rand = arc4random();
+ cookie[i] = rand;
+ rand >>= 8;
+ }
packet_start(SSH2_MSG_KEXINIT);
packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
packet_send();
}
void
-kex_input_kexinit(int type, int plen, void *ctxt)
+kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
{
char *ptr;
int dlen;
+ int i;
Kex *kex = (Kex *)ctxt;
debug("SSH2_MSG_KEXINIT received");
+ if (kex == NULL)
+ fatal("kex_input_kexinit: no kex, cannot rekey");
ptr = packet_get_raw(&dlen);
buffer_append(&kex->peer, ptr, dlen);
+ /* discard packet */
+ for (i = 0; i < KEX_COOKIE_LEN; i++)
+ packet_get_char();
+ for (i = 0; i < PROPOSAL_MAX; i++)
+ xfree(packet_get_string(NULL));
+ (void) packet_get_char();
+ (void) packet_get_int();
+ packet_check_eom();
+
kex_kexinit_finish(kex);
}
kex_setup(char *proposal[PROPOSAL_MAX])
{
Kex *kex;
- int i;
kex = xmalloc(sizeof(*kex));
memset(kex, 0, sizeof(*kex));
buffer_init(&kex->peer);
buffer_init(&kex->my);
kex_prop2buf(&kex->my, proposal);
- kex->newkeys = 0;
+ kex->done = 0;
kex_send_kexinit(kex); /* we start */
- /* Numbers 30-49 are used for kex packets */
- for (i = 30; i <= 49; i++)
- dispatch_set(i, kex_protocol_error);
+ kex_reset_dispatch();
- dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
return kex;
}
-void
+static void
kex_kexinit_finish(Kex *kex)
{
if (!(kex->flags & KEX_INIT_SENT))
kex_choose_conf(kex);
- switch(kex->kex_type) {
+ switch (kex->kex_type) {
case DH_GRP1_SHA1:
kexdh(kex);
break;
}
}
-void
+static void
choose_enc(Enc *enc, char *client, char *server)
{
char *name = match_list(client, server, NULL);
if (name == NULL)
fatal("no matching cipher found: client %s server %s", client, server);
- enc->cipher = cipher_by_name(name);
- if (enc->cipher == NULL)
+ if ((enc->cipher = cipher_by_name(name)) == NULL)
fatal("matching cipher is not supported: %s", name);
enc->name = name;
enc->enabled = 0;
enc->iv = NULL;
enc->key = NULL;
+ enc->key_len = cipher_keylen(enc->cipher);
+ enc->block_size = cipher_blocksize(enc->cipher);
}
-void
+static void
choose_mac(Mac *mac, char *client, char *server)
{
char *name = match_list(client, server, NULL);
mac->key = NULL;
mac->enabled = 0;
}
-void
+static void
choose_comp(Comp *comp, char *client, char *server)
{
char *name = match_list(client, server, NULL);
}
comp->name = name;
}
-void
+static void
choose_kex(Kex *k, char *client, char *server)
{
k->name = match_list(client, server, NULL);
} else
fatal("bad kex alg %s", k->name);
}
-void
+static void
choose_hostkeyalg(Kex *k, char *client, char *server)
{
char *hostkeyalg = match_list(client, server, NULL);
xfree(hostkeyalg);
}
-void
+static void
kex_choose_conf(Kex *kex)
{
Newkeys *newkeys;
sprop=peer;
}
+ /* Algorithm Negotiation */
for (mode = 0; mode < MODE_MAX; mode++) {
newkeys = xmalloc(sizeof(*newkeys));
memset(newkeys, 0, sizeof(*newkeys));
- kex->keys[mode] = newkeys;
+ kex->newkeys[mode] = newkeys;
ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
need = 0;
for (mode = 0; mode < MODE_MAX; mode++) {
- newkeys = kex->keys[mode];
- if (need < newkeys->enc.cipher->key_len)
- need = newkeys->enc.cipher->key_len;
- if (need < newkeys->enc.cipher->block_size)
- need = newkeys->enc.cipher->block_size;
+ newkeys = kex->newkeys[mode];
+ if (need < newkeys->enc.key_len)
+ need = newkeys->enc.key_len;
+ if (need < newkeys->enc.block_size)
+ need = newkeys->enc.block_size;
if (need < newkeys->mac.key_len)
need = newkeys->mac.key_len;
}
kex_prop_free(peer);
}
-u_char *
+static u_char *
derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
{
Buffer b;
- EVP_MD *evp_md = EVP_sha1();
+ const EVP_MD *evp_md = EVP_sha1();
EVP_MD_CTX md;
char c = id;
int have;
- int mdsz = evp_md->md_size;
- u_char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz);
+ int mdsz = EVP_MD_size(evp_md);
+ u_char *digest = xmalloc(roundup(need, mdsz));
buffer_init(&b);
buffer_put_bignum2(&b, shared_secret);
+ /* K1 = HASH(K || H || "A" || session_id) */
EVP_DigestInit(&md, evp_md);
- EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); /* shared_secret K */
- EVP_DigestUpdate(&md, hash, mdsz); /* transport-06 */
- EVP_DigestUpdate(&md, &c, 1); /* key id */
+ if (!(datafellows & SSH_BUG_DERIVEKEY))
+ EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+ EVP_DigestUpdate(&md, hash, mdsz);
+ EVP_DigestUpdate(&md, &c, 1);
EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
EVP_DigestFinal(&md, digest, NULL);
- /* expand */
+ /*
+ * expand key:
+ * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
+ * Key = K1 || K2 || ... || Kn
+ */
for (have = mdsz; need > have; have += mdsz) {
EVP_DigestInit(&md, evp_md);
- EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+ if (!(datafellows & SSH_BUG_DERIVEKEY))
+ EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
EVP_DigestUpdate(&md, hash, mdsz);
EVP_DigestUpdate(&md, digest, have);
EVP_DigestFinal(&md, digest + have, NULL);
return digest;
}
-Newkeys *x_newkeys[MODE_MAX];
+Newkeys *current_keys[MODE_MAX];
#define NKEYS 6
void
kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
{
- Newkeys *newkeys;
u_char *keys[NKEYS];
int i, mode, ctos;
for (i = 0; i < NKEYS; i++)
keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
- debug("kex_derive_keys");
+ debug2("kex_derive_keys");
for (mode = 0; mode < MODE_MAX; mode++) {
- newkeys = kex->keys[mode];
+ current_keys[mode] = kex->newkeys[mode];
+ kex->newkeys[mode] = NULL;
ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
- newkeys->enc.iv = keys[ctos ? 0 : 1];
- newkeys->enc.key = keys[ctos ? 2 : 3];
- newkeys->mac.key = keys[ctos ? 4 : 5];
- x_newkeys[mode] = newkeys;
+ current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
+ current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
+ current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
}
}
Newkeys *
kex_get_newkeys(int mode)
{
- return x_newkeys[mode];
+ Newkeys *ret;
+
+ ret = current_keys[mode];
+ current_keys[mode] = NULL;
+ return ret;
}
#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
int i;
fprintf(stderr, "%s\n", msg);
- for (i = 0; i< len; i++){
+ for (i = 0; i< len; i++) {
fprintf(stderr, "%02x", digest[i]);
if (i%32 == 31)
fprintf(stderr, "\n");
andersk / openssh.git / blobdiff