Import of OpenSSH 3.6.1p1

[gssapi-openssh.git] / openssh / kex.c

diff --git a/openssh/kex.c b/openssh/kex.c
index bdbf3882c82b3d0e3505418b488e21b0637f4055..b070ccf42eb2fb66402d6d511c19ec5e14628b4f 100644 (file)
--- a/openssh/kex.c
+++ b/openssh/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.51 2002/06/24 14:55:38 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.55 2003/04/01 10:31:26 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -44,11 +44,6 @@ RCSID("$OpenBSD: kex.c,v 1.51 2002/06/24 14:55:38 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 *);
@@ -74,7 +69,7 @@ kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
 
 /* parse buffer and return algorithm proposal */
 static char **
-kex_buf2prop(Buffer *raw)
+kex_buf2prop(Buffer *raw, int *first_kex_follows)
 {
        Buffer b;
        int i;
@@ -94,6 +89,8 @@ kex_buf2prop(Buffer *raw)
        }
        /* first kex follows / reserved */
        i = buffer_get_char(&b);
+       if (first_kex_follows != NULL)
+               *first_kex_follows = i;
        debug2("kex_parse_kexinit: first_kex_follows %d ", i);
        i = buffer_get_int(&b);
        debug2("kex_parse_kexinit: reserved %d ", i);
@@ -135,7 +132,7 @@ kex_finish(Kex *kex)
        /* packet_write_wait(); */
        debug("SSH2_MSG_NEWKEYS sent");
 
-       debug("waiting for SSH2_MSG_NEWKEYS");
+       debug("expecting SSH2_MSG_NEWKEYS");
        packet_read_expect(SSH2_MSG_NEWKEYS);
        packet_check_eom();
        debug("SSH2_MSG_NEWKEYS received");
@@ -235,14 +232,10 @@ 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);
        }
 }
@@ -299,9 +292,9 @@ 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_DHGEX) == 0) {
-               k->kex_type = DH_GEX_SHA1;
+               k->kex_type = KEX_DH_GEX_SHA1;
        } else
                fatal("bad kex alg %s", k->name);
 }
@@ -317,6 +310,30 @@ choose_hostkeyalg(Kex *k, char *client, char *server)
        xfree(hostkeyalg);
 }
 
+static int 
+proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
+{
+       static int check[] = {
+               PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
+       };
+       int *idx;
+       char *p;
+
+       for (idx = &check[0]; *idx != -1; idx++) {
+               if ((p = strchr(my[*idx], ',')) != NULL)
+                       *p = '\0';
+               if ((p = strchr(peer[*idx], ',')) != NULL)
+                       *p = '\0';
+               if (strcmp(my[*idx], peer[*idx]) != 0) {
+                       debug2("proposal mismatch: my %s peer %s",
+                           my[*idx], peer[*idx]);
+                       return (0);
+               }
+       }
+       debug2("proposals match");
+       return (1);
+}
+
 static void
 kex_choose_conf(Kex *kex)
 {
@@ -327,9 +344,10 @@ kex_choose_conf(Kex *kex)
        int mode;
        int ctos;                               /* direction: if true client-to-server */
        int need;
+       int first_kex_follows, type;
 
-       my   = kex_buf2prop(&kex->my);
-       peer = kex_buf2prop(&kex->peer);
+       my   = kex_buf2prop(&kex->my, NULL);
+       peer = kex_buf2prop(&kex->peer, &first_kex_follows);
 
        if (kex->server) {
                cprop=peer;
@@ -373,6 +391,13 @@ kex_choose_conf(Kex *kex)
        /* XXX need runden? */
        kex->we_need = need;
 
+       /* ignore the next message if the proposals do not match */
+       if (first_kex_follows && !proposals_match(my, peer) && 
+          !(datafellows & SSH_BUG_FIRSTKEX)) {
+               type = packet_read();
+               debug2("skipping next packet (type %u)", type);
+       }
+
        kex_prop_free(my);
        kex_prop_free(peer);
 }
@@ -433,7 +458,7 @@ kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
        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++) {
                current_keys[mode] = kex->newkeys[mode];
                kex->newkeys[mode] = NULL;