- djm@cvs.openbsd.org 2005/07/17 07:17:55

[openssh.git] / kex.c

diff --git a/kex.c b/kex.c
index 0a861fb976c1b992754eaee5bce63c00ca6ee97f..06a3ad4ccd0cf313e8c2726d2de450be4a420b65 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.53 2003/02/02 10:56:08 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.63 2005/07/17 07:17:55 djm Exp $");
 
 #include <openssl/crypto.h>
 
@@ -44,11 +44,6 @@ RCSID("$OpenBSD: kex.c,v 1.53 2003/02/02 10:56:08 markus Exp $");
 
 #define KEX_COOKIE_LEN 16
 
-/* Use privilege separation for sshd */
-int use_privsep;
-struct monitor *pmonitor;
-
-
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
@@ -57,7 +52,7 @@ static void kex_choose_conf(Kex *);
 static void
 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
 {
-       int i;
+       u_int i;
 
        buffer_clear(b);
        /*
@@ -106,7 +101,7 @@ kex_buf2prop(Buffer *raw, int *first_kex_follows)
 static void
 kex_prop_free(char **proposal)
 {
-       int i;
+       u_int i;
 
        for (i = 0; i < PROPOSAL_MAX; i++)
                xfree(proposal[i]);
@@ -153,9 +148,9 @@ kex_finish(Kex *kex)
 void
 kex_send_kexinit(Kex *kex)
 {
-       u_int32_t rand = 0;
+       u_int32_t rnd = 0;
        u_char *cookie;
-       int i;
+       u_int i;
 
        if (kex == NULL) {
                error("kex_send_kexinit: no kex, cannot rekey");
@@ -173,9 +168,9 @@ kex_send_kexinit(Kex *kex)
        cookie = buffer_ptr(&kex->my);
        for (i = 0; i < KEX_COOKIE_LEN; i++) {
                if (i % 4 == 0)
-                       rand = arc4random();
-               cookie[i] = rand;
-               rand >>= 8;
+                       rnd = arc4random();
+               cookie[i] = rnd;
+               rnd >>= 8;
        }
        packet_start(SSH2_MSG_KEXINIT);
        packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
@@ -188,8 +183,7 @@ void
 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
 {
        char *ptr;
-       int dlen;
-       int i;
+       u_int i, dlen;
        Kex *kex = (Kex *)ctxt;
 
        debug("SSH2_MSG_KEXINIT received");
@@ -237,14 +231,10 @@ kex_kexinit_finish(Kex *kex)
 
        kex_choose_conf(kex);
 
-       switch (kex->kex_type) {
-       case DH_GRP1_SHA1:
-               kexdh(kex);
-               break;
-       case DH_GEX_SHA1:
-               kexgex(kex);
-               break;
-       default:
+       if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
+           kex->kex[kex->kex_type] != NULL) {
+               (kex->kex[kex->kex_type])(kex);
+       } else {
                fatal("Unsupported key exchange %d", kex->kex_type);
        }
 }
@@ -301,9 +291,11 @@ choose_kex(Kex *k, char *client, char *server)
        if (k->name == NULL)
                fatal("no kex alg");
        if (strcmp(k->name, KEX_DH1) == 0) {
-               k->kex_type = DH_GRP1_SHA1;
+               k->kex_type = KEX_DH_GRP1_SHA1;
+       } else if (strcmp(k->name, KEX_DH14) == 0) {
+               k->kex_type = KEX_DH_GRP14_SHA1;
        } else if (strcmp(k->name, KEX_DHGEX) == 0) {
-               k->kex_type = DH_GEX_SHA1;
+               k->kex_type = KEX_DH_GEX_SHA1;
        } else
                fatal("bad kex alg %s", k->name);
 }
@@ -319,7 +311,7 @@ choose_hostkeyalg(Kex *k, char *client, char *server)
        xfree(hostkeyalg);
 }
 
-static int 
+static int
 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
 {
        static int check[] = {
@@ -350,9 +342,7 @@ kex_choose_conf(Kex *kex)
        char **my, **peer;
        char **cprop, **sprop;
        int nenc, nmac, ncomp;
-       int mode;
-       int ctos;                               /* direction: if true client-to-server */
-       int need;
+       u_int mode, ctos, need;
        int first_kex_follows, type;
 
        my   = kex_buf2prop(&kex->my, NULL);
@@ -401,7 +391,8 @@ kex_choose_conf(Kex *kex)
        kex->we_need = need;
 
        /* ignore the next message if the proposals do not match */
-       if (first_kex_follows && !proposals_match(my, peer)) {
+       if (first_kex_follows && !proposals_match(my, peer) &&
+           !(datafellows & SSH_BUG_FIRSTKEX)) {
                type = packet_read();
                debug2("skipping next packet (type %u)", type);
        }
@@ -411,15 +402,19 @@ kex_choose_conf(Kex *kex)
 }
 
 static u_char *
-derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
+derive_key(Kex *kex, int id, u_int need, u_char *hash, BIGNUM *shared_secret)
 {
        Buffer b;
        const EVP_MD *evp_md = EVP_sha1();
        EVP_MD_CTX md;
        char c = id;
-       int have;
+       u_int have;
        int mdsz = EVP_MD_size(evp_md);
-       u_char *digest = xmalloc(roundup(need, mdsz));
+       u_char *digest;
+
+       if (mdsz < 0)
+               fatal("derive_key: mdsz < 0");
+       digest = xmalloc(roundup(need, mdsz));
 
        buffer_init(&b);
        buffer_put_bignum2(&b, shared_secret);
@@ -461,7 +456,7 @@ void
 kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
 {
        u_char *keys[NKEYS];
-       int i, mode, ctos;
+       u_int i, mode, ctos;
 
        for (i = 0; i < NKEYS; i++)
                keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
@@ -487,11 +482,44 @@ kex_get_newkeys(int mode)
        return ret;
 }
 
+void
+derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
+    u_int8_t cookie[8], u_int8_t id[16])
+{
+       const EVP_MD *evp_md = EVP_md5();
+       EVP_MD_CTX md;
+       u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
+       int len;
+
+       EVP_DigestInit(&md, evp_md);
+
+       len = BN_num_bytes(host_modulus);
+       if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
+               fatal("%s: bad host modulus (len %d)", __func__, len);
+       BN_bn2bin(host_modulus, nbuf);
+       EVP_DigestUpdate(&md, nbuf, len);
+
+       len = BN_num_bytes(server_modulus);
+       if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
+               fatal("%s: bad server modulus (len %d)", __func__, len);
+       BN_bn2bin(server_modulus, nbuf);
+       EVP_DigestUpdate(&md, nbuf, len);
+
+       EVP_DigestUpdate(&md, cookie, 8);
+
+       EVP_DigestFinal(&md, obuf, NULL);
+       memcpy(id, obuf, 16);
+
+       memset(nbuf, 0, sizeof(nbuf));
+       memset(obuf, 0, sizeof(obuf));
+       memset(&md, 0, sizeof(md));
+}
+
 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
 void
 dump_digest(char *msg, u_char *digest, int len)
 {
-       int i;
+       u_int i;
 
        fprintf(stderr, "%s\n", msg);
        for (i = 0; i< len; i++) {