- itojun@cvs.openbsd.org 2002/10/16 14:31:48

[openssh.git] / kex.c

diff --git a/kex.c b/kex.c
index b58b12f402bf2f17e6a4114aac3c72e8da8322eb..bdbf3882c82b3d0e3505418b488e21b0637f4055 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.43 2002/01/25 22:07:40 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.51 2002/06/24 14:55:38 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -40,9 +40,15 @@ RCSID("$OpenBSD: kex.c,v 1.43 2002/01/25 22:07:40 markus Exp $");
 #include "mac.h"
 #include "match.h"
 #include "dispatch.h"
+#include "monitor.h"
 
 #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 *);
@@ -51,16 +57,15 @@ static void kex_choose_conf(Kex *);
 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 */
@@ -113,16 +118,17 @@ kex_protocol_error(int type, u_int32_t seq, void *ctxt)
 }
 
 static void
-kex_clear_dispatch(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)
 {
-       kex_clear_dispatch();
+       kex_reset_dispatch();
 
        packet_start(SSH2_MSG_NEWKEYS);
        packet_send();
@@ -131,6 +137,7 @@ kex_finish(Kex *kex)
 
        debug("waiting for SSH2_MSG_NEWKEYS");
        packet_read_expect(SSH2_MSG_NEWKEYS);
+       packet_check_eom();
        debug("SSH2_MSG_NEWKEYS received");
 
        kex->done = 1;
@@ -144,6 +151,10 @@ kex_finish(Kex *kex)
 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;
@@ -153,6 +164,17 @@ kex_send_kexinit(Kex *kex)
                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();
@@ -180,8 +202,8 @@ kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
                packet_get_char();
        for (i = 0; i < PROPOSAL_MAX; i++)
                xfree(packet_get_string(NULL));
-       packet_get_char();
-       packet_get_int();
+       (void) packet_get_char();
+       (void) packet_get_int();
        packet_check_eom();
 
        kex_kexinit_finish(kex);
@@ -200,8 +222,7 @@ kex_setup(char *proposal[PROPOSAL_MAX])
        kex->done = 0;
 
        kex_send_kexinit(kex);                                  /* we start */
-       kex_clear_dispatch();
-       dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
+       kex_reset_dispatch();
 
        return kex;
 }
@@ -232,13 +253,14 @@ 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);
 }
 static void
 choose_mac(Mac *mac, char *client, char *server)
@@ -341,10 +363,10 @@ kex_choose_conf(Kex *kex)
        need = 0;
        for (mode = 0; mode < MODE_MAX; mode++) {
                newkeys = kex->newkeys[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;
+               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;
        }
@@ -359,7 +381,7 @@ 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;