- markus@cvs.openbsd.org 2001/04/03 19:53:29
[dh.c dh.h kex.c kex.h sshconnect2.c sshd.c]
move kex to kex*.c, used dispatch_set() callbacks for kex. should
make rekeying easier.
diff --git a/kex.c b/kex.c
index 576d4b5..a0a5b46 100644
--- a/kex.c
+++ b/kex.c
@@ -23,12 +23,9 @@
*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.25 2001/03/29 21:17:39 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.26 2001/04/03 19:53:29 markus Exp $");
#include <openssl/crypto.h>
-#include <openssl/bio.h>
-#include <openssl/bn.h>
-#include <openssl/pem.h>
#include "ssh2.h"
#include "xmalloc.h"
@@ -42,233 +39,169 @@
#include "log.h"
#include "mac.h"
#include "match.h"
+#include "dispatch.h"
#define KEX_COOKIE_LEN 16
-Buffer *
-kex_init(char *myproposal[PROPOSAL_MAX])
+void kex_kexinit_finish(Kex *kex);
+void kex_choose_conf(Kex *k);
+
+/* put algorithm proposal into buffer */
+void
+kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
- int first_kex_packet_follows = 0;
- u_char cookie[KEX_COOKIE_LEN];
u_int32_t rand = 0;
int i;
- Buffer *ki = xmalloc(sizeof(*ki));
+
+ buffer_clear(b);
for (i = 0; i < KEX_COOKIE_LEN; i++) {
if (i % 4 == 0)
rand = arc4random();
- cookie[i] = rand & 0xff;
+ buffer_put_char(b, rand & 0xff);
rand >>= 8;
}
- buffer_init(ki);
- buffer_append(ki, (char *)cookie, sizeof cookie);
for (i = 0; i < PROPOSAL_MAX; i++)
- buffer_put_cstring(ki, myproposal[i]);
- buffer_put_char(ki, first_kex_packet_follows);
- buffer_put_int(ki, 0); /* uint32 reserved */
- return ki;
+ buffer_put_cstring(b, proposal[i]);
+ buffer_put_char(b, 0); /* first_kex_packet_follows */
+ buffer_put_int(b, 0); /* uint32 reserved */
}
-/* send kexinit, parse and save reply */
-void
-kex_exchange_kexinit(
- Buffer *my_kexinit, Buffer *peer_kexint,
- char *peer_proposal[PROPOSAL_MAX])
+/* parse buffer and return algorithm proposal */
+char **
+kex_buf2prop(Buffer *raw)
{
+ Buffer b;
int i;
- char *ptr;
- int plen;
+ char **proposal;
- debug("send KEXINIT");
- packet_start(SSH2_MSG_KEXINIT);
- packet_put_raw(buffer_ptr(my_kexinit), buffer_len(my_kexinit));
- packet_send();
- packet_write_wait();
- debug("done");
+ proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));
- /*
- * read and save raw KEXINIT payload in buffer. this is used during
- * computation of the session_id and the session keys.
- */
- debug("wait KEXINIT");
- packet_read_expect(&plen, SSH2_MSG_KEXINIT);
- ptr = packet_get_raw(&plen);
- buffer_append(peer_kexint, ptr, plen);
-
- /* parse packet and save algorithm proposal */
+ buffer_init(&b);
+ buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
/* skip cookie */
for (i = 0; i < KEX_COOKIE_LEN; i++)
- packet_get_char();
+ buffer_get_char(&b);
/* extract kex init proposal strings */
for (i = 0; i < PROPOSAL_MAX; i++) {
- peer_proposal[i] = packet_get_string(NULL);
- debug("got kexinit: %s", peer_proposal[i]);
+ proposal[i] = buffer_get_string(&b,NULL);
+ debug2("kex_parse_kexinit: %s", proposal[i]);
}
- /* first kex follow / reserved */
- i = packet_get_char();
- debug("first kex follow: %d ", i);
- i = packet_get_int();
- debug("reserved: %d ", i);
- packet_done();
- debug("done");
+ /* first kex follows / reserved */
+ i = buffer_get_char(&b);
+ debug2("kex_parse_kexinit: first_kex_follows %d ", i);
+ i = buffer_get_int(&b);
+ debug2("kex_parse_kexinit: reserved %d ", i);
+ buffer_free(&b);
+ return proposal;
}
-#ifdef DEBUG_KEX
void
-dump_digest(u_char *digest, int len)
+kex_prop_free(char **proposal)
{
int i;
- for (i = 0; i< len; i++){
- fprintf(stderr, "%02x", digest[i]);
- if(i%2!=0)
- fprintf(stderr, " ");
- }
- fprintf(stderr, "\n");
-}
-#endif
-u_char *
-kex_hash(
- char *client_version_string,
- char *server_version_string,
- char *ckexinit, int ckexinitlen,
- char *skexinit, int skexinitlen,
- char *serverhostkeyblob, int sbloblen,
- BIGNUM *client_dh_pub,
- BIGNUM *server_dh_pub,
- BIGNUM *shared_secret)
-{
- Buffer b;
- static u_char digest[EVP_MAX_MD_SIZE];
- EVP_MD *evp_md = EVP_sha1();
- EVP_MD_CTX md;
-
- buffer_init(&b);
- buffer_put_string(&b, client_version_string, strlen(client_version_string));
- buffer_put_string(&b, server_version_string, strlen(server_version_string));
-
- /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
- buffer_put_int(&b, ckexinitlen+1);
- buffer_put_char(&b, SSH2_MSG_KEXINIT);
- buffer_append(&b, ckexinit, ckexinitlen);
- buffer_put_int(&b, skexinitlen+1);
- buffer_put_char(&b, SSH2_MSG_KEXINIT);
- buffer_append(&b, skexinit, skexinitlen);
-
- buffer_put_string(&b, serverhostkeyblob, sbloblen);
- buffer_put_bignum2(&b, client_dh_pub);
- buffer_put_bignum2(&b, server_dh_pub);
- buffer_put_bignum2(&b, shared_secret);
-
-#ifdef DEBUG_KEX
- buffer_dump(&b);
-#endif
-
- EVP_DigestInit(&md, evp_md);
- EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
- EVP_DigestFinal(&md, digest, NULL);
-
- buffer_free(&b);
-
-#ifdef DEBUG_KEX
- dump_digest(digest, evp_md->md_size);
-#endif
- return digest;
+ for (i = 0; i < PROPOSAL_MAX; i++)
+ xfree(proposal[i]);
+ xfree(proposal);
}
-u_char *
-kex_hash_gex(
- char *client_version_string,
- char *server_version_string,
- char *ckexinit, int ckexinitlen,
- char *skexinit, int skexinitlen,
- char *serverhostkeyblob, int sbloblen,
- int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
- BIGNUM *client_dh_pub,
- BIGNUM *server_dh_pub,
- BIGNUM *shared_secret)
+void
+kex_protocol_error(int type, int plen, void *ctxt)
{
- Buffer b;
- static u_char digest[EVP_MAX_MD_SIZE];
- EVP_MD *evp_md = EVP_sha1();
- EVP_MD_CTX md;
-
- buffer_init(&b);
- buffer_put_string(&b, client_version_string, strlen(client_version_string));
- buffer_put_string(&b, server_version_string, strlen(server_version_string));
-
- /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
- buffer_put_int(&b, ckexinitlen+1);
- buffer_put_char(&b, SSH2_MSG_KEXINIT);
- buffer_append(&b, ckexinit, ckexinitlen);
- buffer_put_int(&b, skexinitlen+1);
- buffer_put_char(&b, SSH2_MSG_KEXINIT);
- buffer_append(&b, skexinit, skexinitlen);
-
- buffer_put_string(&b, serverhostkeyblob, sbloblen);
- if (min == -1 || max == -1)
- buffer_put_int(&b, wantbits);
- else {
- buffer_put_int(&b, min);
- buffer_put_int(&b, wantbits);
- buffer_put_int(&b, max);
- }
- buffer_put_bignum2(&b, prime);
- buffer_put_bignum2(&b, gen);
- buffer_put_bignum2(&b, client_dh_pub);
- buffer_put_bignum2(&b, server_dh_pub);
- buffer_put_bignum2(&b, shared_secret);
-
-#ifdef DEBUG_KEX
- buffer_dump(&b);
-#endif
-
- EVP_DigestInit(&md, evp_md);
- EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
- EVP_DigestFinal(&md, digest, NULL);
-
- buffer_free(&b);
-
-#ifdef DEBUG_KEX
- dump_digest(digest, evp_md->md_size);
-#endif
- return digest;
+ error("Hm, kex protocol error: type %d plen %d", type, plen);
}
-u_char *
-derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret)
+void
+kex_send_newkeys(void)
{
- Buffer b;
- 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);
+ packet_start(SSH2_MSG_NEWKEYS);
+ packet_send();
+ /* packet_write_wait(); */
+ debug("SSH2_MSG_NEWKEYS sent");
+}
- buffer_init(&b);
- buffer_put_bignum2(&b, shared_secret);
+void
+kex_input_newkeys(int type, int plen, void *ctxt)
+{
+ Kex *kex = ctxt;
+ int i;
- 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 */
- EVP_DigestUpdate(&md, hash, mdsz); /* session id */
- EVP_DigestFinal(&md, digest, NULL);
+ debug("SSH2_MSG_NEWKEYS received");
+ kex->newkeys = 1;
+ for (i = 30; i <= 49; i++)
+ dispatch_set(i, &kex_protocol_error);
+ buffer_clear(&kex->peer);
+ buffer_clear(&kex->my);
+ kex->flags &= ~KEX_INIT_SENT;
+}
- /* expand */
- for (have = mdsz; need > have; have += mdsz) {
- EVP_DigestInit(&md, evp_md);
- 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);
+void
+kex_send_kexinit(Kex *kex)
+{
+ packet_start(SSH2_MSG_KEXINIT);
+ packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
+ packet_send();
+ debug("SSH2_MSG_KEXINIT sent");
+ kex->flags |= KEX_INIT_SENT;
+}
+
+void
+kex_input_kexinit(int type, int plen, void *ctxt)
+{
+ char *ptr;
+ int dlen;
+ Kex *kex = (Kex *)ctxt;
+
+ dispatch_set(SSH2_MSG_KEXINIT, &kex_protocol_error);
+ debug("SSH2_MSG_KEXINIT received");
+
+ ptr = packet_get_raw(&dlen);
+ buffer_append(&kex->peer, ptr, dlen);
+
+ kex_kexinit_finish(kex);
+}
+
+Kex *
+kex_start(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_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);
+
+ dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
+ dispatch_set(SSH2_MSG_NEWKEYS, &kex_input_newkeys);
+ return kex;
+}
+
+void
+kex_kexinit_finish(Kex *kex)
+{
+ if (!(kex->flags & KEX_INIT_SENT))
+ kex_send_kexinit(kex);
+
+ kex_choose_conf(kex);
+
+ switch(kex->kex_type) {
+ case DH_GRP1_SHA1:
+ kexdh(kex);
+ break;
+ case DH_GEX_SHA1:
+ kexgex(kex);
+ break;
+ default:
+ fatal("Unsupported key exchange %d", kex->kex_type);
}
- buffer_free(&b);
-#ifdef DEBUG_KEX
- fprintf(stderr, "Digest '%c'== ", c);
- dump_digest(digest, need);
-#endif
- return digest;
}
void
@@ -340,17 +273,25 @@
xfree(hostkeyalg);
}
-Kex *
-kex_choose_conf(char *cprop[PROPOSAL_MAX], char *sprop[PROPOSAL_MAX], int server)
+void
+kex_choose_conf(Kex *k)
{
+ char **my, **peer;
+ char **cprop, **sprop;
int mode;
int ctos; /* direction: if true client-to-server */
int need;
- Kex *k;
- k = xmalloc(sizeof(*k));
- memset(k, 0, sizeof(*k));
- k->server = server;
+ my = kex_buf2prop(&k->my);
+ peer = kex_buf2prop(&k->peer);
+
+ if (k->server) {
+ cprop=peer;
+ sprop=my;
+ } else {
+ cprop=my;
+ sprop=peer;
+ }
for (mode = 0; mode < MODE_MAX; mode++) {
int nenc, nmac, ncomp;
@@ -381,11 +322,51 @@
}
/* XXX need runden? */
k->we_need = need;
- return k;
+
+ kex_prop_free(my);
+ kex_prop_free(peer);
+
+}
+
+u_char *
+derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret)
+{
+ Buffer b;
+ 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);
+
+ buffer_init(&b);
+ buffer_put_bignum2(&b, shared_secret);
+
+ 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 */
+ EVP_DigestUpdate(&md, hash, mdsz); /* session id */
+ EVP_DigestFinal(&md, digest, NULL);
+
+ /* expand */
+ for (have = mdsz; need > have; have += mdsz) {
+ EVP_DigestInit(&md, evp_md);
+ 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);
+ }
+ buffer_free(&b);
+#ifdef DEBUG_KEX
+ fprintf(stderr, "key '%c'== ", c);
+ dump_digest("key", digest, need);
+#endif
+ return digest;
}
#define NKEYS 6
-int
+void
kex_derive_keys(Kex *k, u_char *hash, BIGNUM *shared_secret)
{
int i;
@@ -402,5 +383,22 @@
k->enc[mode].key = keys[ctos ? 2 : 3];
k->mac[mode].key = keys[ctos ? 4 : 5];
}
- return 0;
}
+
+#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
+void
+dump_digest(char *msg, u_char *digest, int len)
+{
+ int i;
+
+ fprintf(stderr, "%s\n", msg);
+ for (i = 0; i< len; i++){
+ fprintf(stderr, "%02x", digest[i]);
+ if (i%32 == 31)
+ fprintf(stderr, "\n");
+ else if (i%8 == 7)
+ fprintf(stderr, " ");
+ }
+ fprintf(stderr, "\n");
+}
+#endif