- markus@cvs.openbsd.org 2002/11/21 22:45:31

[openssh.git] / kex.c

diff --git a/kex.c b/kex.c
index 1a412ce0fcab2c98104d184d046b7b3c852a7880..113663598eff617c8ce57734363ff0badb442efa 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.36 2001/06/25 08:25:37 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.52 2002/11/21 22:45:31 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -40,9 +40,15 @@ RCSID("$OpenBSD: kex.c,v 1.36 2001/06/25 08:25:37 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 */
@@ -107,35 +112,32 @@ kex_prop_free(char **proposal)
 }
 
 static void
-kex_protocol_error(int type, int plen, void *ctxt)
+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_clear_dispatch(void)
+kex_reset_dispatch(void)
 {
-       int i;
-
-       /* Numbers 30-49 are used for kex packets */
-       for (i = 30; i <= 49; i++)
-               dispatch_set(i, &kex_protocol_error);
+       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 plen;
-
-       kex_clear_dispatch();
+       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->done = 1;
@@ -149,6 +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;
@@ -158,6 +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();
@@ -166,7 +183,7 @@ kex_send_kexinit(Kex *kex)
 }
 
 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;
@@ -185,9 +202,9 @@ kex_input_kexinit(int type, int plen, void *ctxt)
                packet_get_char();
        for (i = 0; i < PROPOSAL_MAX; i++)
                xfree(packet_get_string(NULL));
-       packet_get_char();
-       packet_get_int();
-       packet_done();
+       (void) packet_get_char();
+       (void) packet_get_int();
+       packet_check_eom();
 
        kex_kexinit_finish(kex);
 }
@@ -205,8 +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;
 }
@@ -219,7 +235,7 @@ kex_kexinit_finish(Kex *kex)
 
        kex_choose_conf(kex);
 
-       switch(kex->kex_type) {
+       switch (kex->kex_type) {
        case DH_GRP1_SHA1:
                kexdh(kex);
                break;
@@ -237,13 +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)
@@ -346,10 +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;
        }
@@ -364,11 +381,11 @@ 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;
+       int mdsz = EVP_MD_size(evp_md);
        u_char *digest = xmalloc(roundup(need, mdsz));
 
        buffer_init(&b);
@@ -416,7 +433,7 @@ 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;
@@ -444,7 +461,7 @@ dump_digest(char *msg, u_char *digest, int len)
        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");