- markus@cvs.openbsd.org 2001/04/04 20:25:38

     [channels.c channels.h clientloop.c kex.c kex.h serverloop.c
      sshconnect2.c sshd.c]
     more robust rekeying
     don't send channel data after rekeying is started.

9 files changed, 96 insertions, 63 deletions

diff --git a/ChangeLog b/ChangeLog
index 7bb8eaa5c..83c02ecf5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,11 @@
    - markus@cvs.openbsd.org 2001/04/04 15:50:55
      [compat.c]
      f-secure 1.3.2 does not handle IGNORE; from milliondl@ornl.gov
+   - markus@cvs.openbsd.org 2001/04/04 20:25:38
+     [channels.c channels.h clientloop.c kex.c kex.h serverloop.c 
+      sshconnect2.c sshd.c]
+     more robust rekeying
+     don't send channel data after rekeying is started.
 
 20010404
  - OpenBSD CVS Sync
@@ -4851,4 +4856,4 @@
  - Wrote replacements for strlcpy and mkdtemp
  - Released 1.0pre1
 
-$Id: ChangeLog,v 1.1057 2001/04/04 23:43:26 mouring Exp $
+$Id: ChangeLog,v 1.1058 2001/04/04 23:46:07 mouring Exp $
diff --git a/channels.c b/channels.c
index 941556ace..7790564cc 100644
--- a/channels.c
+++ b/channels.c
@@ -40,7 +40,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: channels.c,v 1.99 2001/03/16 19:06:29 markus Exp $");
+RCSID("$OpenBSD: channels.c,v 1.100 2001/04/04 20:25:35 markus Exp $");
 
 #include <openssl/rsa.h>
 #include <openssl/dsa.h>
@@ -1005,7 +1005,8 @@ channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
 }
 
 void
-channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp)
+channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+    int rekeying)
 {
         int n;
         u_int sz;
@@ -1025,7 +1026,8 @@ channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp)
         memset(*readsetp, 0, sz);
         memset(*writesetp, 0, sz);
 
-        channel_handler(channel_pre, *readsetp, *writesetp);
+        if (!rekeying)
+                channel_handler(channel_pre, *readsetp, *writesetp);
 }
 
 void
diff --git a/channels.h b/channels.h
index 493b04aa2..2cd82148e 100644
--- a/channels.h
+++ b/channels.h
@@ -32,7 +32,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-/* RCSID("$OpenBSD: channels.h,v 1.28 2001/03/16 19:06:29 markus Exp $"); */
+/* RCSID("$OpenBSD: channels.h,v 1.29 2001/04/04 20:25:36 markus Exp $"); */
 
 #ifndef CHANNELS_H
 #define CHANNELS_H
@@ -171,7 +171,8 @@ void    channel_free(int channel);
  * select bitmasks.
  */
 void
-channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp);
+channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+    int rekeying);
 
 /*
  * After select, perform any appropriate operations for channels which have
diff --git a/clientloop.c b/clientloop.c
index 1d09a8dd9..4b87e3b6d 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -59,7 +59,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: clientloop.c,v 1.55 2001/04/04 14:34:58 markus Exp $");
+RCSID("$OpenBSD: clientloop.c,v 1.56 2001/04/04 20:25:37 markus Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -127,6 +127,7 @@ static u_long stdin_bytes, stdout_bytes, stderr_bytes;
 static u_int buffer_high;/* Soft max buffer size. */
 static int connection_in;       /* Connection to server (input). */
 static int connection_out;      /* Connection to server (output). */
+static int need_rekeying;       /* Set to non-zero if rekeying is requested. */
 
 void    client_init_dispatch(void);
 int     session_ident = -1;
@@ -367,10 +368,10 @@ client_check_window_change(void)
 
 void
 client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
-    int *maxfdp)
+    int *maxfdp, int rekeying)
 {
         /* Add any selections by the channel mechanism. */
-        channel_prepare_select(readsetp, writesetp, maxfdp);
+        channel_prepare_select(readsetp, writesetp, maxfdp, rekeying);
 
         if (!compat20) {
                 /* Read from the connection, unless our buffers are full. */
@@ -553,8 +554,8 @@ process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
                                 continue;
 
                         case 'R':
-                                debug("Rekeying");
-                                kex_send_kexinit(xxx_kex);
+                                if (compat20)
+                                        need_rekeying = 1;
                                 continue;
 
                         case '&':
@@ -794,9 +795,8 @@ int
 client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 {
         fd_set *readset = NULL, *writeset = NULL;
-        int max_fd = 0;
         double start_time, total_time;
-        int len;
+        int max_fd = 0, len, rekeying = 0;
         char buf[100];
 
         debug("Entering interactive session.");
@@ -858,45 +858,60 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
                 /* Process buffered packets sent by the server. */
                 client_process_buffered_input_packets();
 
+                rekeying = (xxx_kex != NULL && !xxx_kex->done);
+
                 if (compat20 && !channel_still_open()) {
                         debug2("!channel_still_open.");
                         break;
                 }
 
-                /*
-                 * Make packets of buffered stdin data, and buffer them for
-                 * sending to the server.
-                 */
-                if (!compat20)
-                        client_make_packets_from_stdin_data();
-
-                /*
-                 * Make packets from buffered channel data, and enqueue them
-                 * for sending to the server.
-                 */
-                if (packet_not_very_much_data_to_write())
-                        channel_output_poll();
+                if (rekeying) {
+                        debug("rekeying in progress");
+                } else {
+                        /*
+                         * Make packets of buffered stdin data, and buffer
+                         * them for sending to the server.
+                         */
+                        if (!compat20)
+                                client_make_packets_from_stdin_data();
 
-                /*
-                 * Check if the window size has changed, and buffer a message
-                 * about it to the server if so.
-                 */
-                client_check_window_change();
+                        /*
+                         * Make packets from buffered channel data, and
+                         * enqueue them for sending to the server.
+                         */
+                        if (packet_not_very_much_data_to_write())
+                                channel_output_poll();
 
-                if (quit_pending)
-                        break;
+                        /*
+                         * Check if the window size has changed, and buffer a
+                         * message about it to the server if so.
+                         */
+                        client_check_window_change();
 
+                        if (quit_pending)
+                                break;
+                }
                 /*
                  * Wait until we have something to do (something becomes
                  * available on one of the descriptors).
                  */
-                client_wait_until_can_do_something(&readset, &writeset, &max_fd);
+                client_wait_until_can_do_something(&readset, &writeset,
+                    &max_fd, rekeying);
 
                 if (quit_pending)
                         break;
 
-                /* Do channel operations. */
-                channel_after_select(readset, writeset);
+                /* Do channel operations unless rekeying in progress. */
+                if (!rekeying) {
+                        channel_after_select(readset, writeset);
+
+                        if (need_rekeying) {
+                                debug("user requests rekeying");
+                                xxx_kex->done = 0;
+                                kex_send_kexinit(xxx_kex);
+                                need_rekeying = 0;
+                        }
+                }
 
                 /* Buffer input from the connection.  */
                 client_process_net_input(readset);
diff --git a/kex.c b/kex.c
index ee1e17e02..da9c56eb0 100644
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.29 2001/04/04 14:34:58 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.30 2001/04/04 20:25:37 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -136,7 +136,7 @@ kex_finish(Kex *kex)
         debug("waiting for SSH2_MSG_NEWKEYS");
         packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
         debug("SSH2_MSG_NEWKEYS received");
-        kex->newkeys = 1;
+        kex->done = 1;
         buffer_clear(&kex->peer);
         /* buffer_clear(&kex->my); */
         kex->flags &= ~KEX_INIT_SENT;
@@ -153,6 +153,7 @@ kex_send_kexinit(Kex *kex)
                 debug("KEX_INIT_SENT");
                 return;
         }
+        kex->done = 0;
         packet_start(SSH2_MSG_KEXINIT);
         packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
         packet_send();
@@ -187,7 +188,7 @@ kex_setup(char *proposal[PROPOSAL_MAX])
         buffer_init(&kex->peer);
         buffer_init(&kex->my);
         kex_prop2buf(&kex->my, proposal);
-        kex->newkeys = 0;
+        kex->done = 0;
 
         kex_send_kexinit(kex);                                  /* we start */
         kex_clear_dispatch();
@@ -307,10 +308,11 @@ kex_choose_conf(Kex *kex)
                 sprop=peer;
         }
 
+        /* Algorithm Negotiation */
         for (mode = 0; mode < MODE_MAX; mode++) {
                 newkeys = xmalloc(sizeof(*newkeys));
                 memset(newkeys, 0, sizeof(*newkeys));
-                kex->keys[mode] = newkeys;
+                kex->newkeys[mode] = newkeys;
                 ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
                 nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
                 nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
@@ -329,7 +331,7 @@ kex_choose_conf(Kex *kex)
             sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
         need = 0;
         for (mode = 0; mode < MODE_MAX; mode++) {
-                newkeys = kex->keys[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)
@@ -353,19 +355,24 @@ derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
         char c = id;
         int have;
         int mdsz = evp_md->md_size;
-        u_char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz);
+        u_char *digest = xmalloc(roundup(need, mdsz));
 
         buffer_init(&b);
         buffer_put_bignum2(&b, shared_secret);
 
+        /* K1 = HASH(K || H || "A" || session_id) */
         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, buffer_ptr(&b), buffer_len(&b));
+        EVP_DigestUpdate(&md, hash, mdsz);
+        EVP_DigestUpdate(&md, &c, 1);
         EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
         EVP_DigestFinal(&md, digest, NULL);
 
-        /* expand */
+        /*
+         * expand key:
+         * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
+         * Key = K1 || K2 || ... || Kn
+         */
         for (have = mdsz; need > have; have += mdsz) {
                 EVP_DigestInit(&md, evp_md);
                 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
@@ -381,13 +388,12 @@ derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
         return digest;
 }
 
-Newkeys *x_newkeys[MODE_MAX];
+Newkeys *current_keys[MODE_MAX];
 
 #define NKEYS   6
 void
 kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
 {
-        Newkeys *newkeys;
         u_char *keys[NKEYS];
         int i, mode, ctos;
 
@@ -396,19 +402,23 @@ kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
 
         debug("kex_derive_keys");
         for (mode = 0; mode < MODE_MAX; mode++) {
-                newkeys = kex->keys[mode];
+                current_keys[mode] = kex->newkeys[mode];
+                kex->newkeys[mode] = NULL;
                 ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
-                newkeys->enc.iv  = keys[ctos ? 0 : 1];
-                newkeys->enc.key = keys[ctos ? 2 : 3];
-                newkeys->mac.key = keys[ctos ? 4 : 5];
-                x_newkeys[mode] = newkeys;
+                current_keys[mode]->enc.iv  = keys[ctos ? 0 : 1];
+                current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
+                current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
         }
 }
 
 Newkeys *
 kex_get_newkeys(int mode)
 {
-        return x_newkeys[mode];
+        Newkeys *ret;
+
+        ret = current_keys[mode];
+        current_keys[mode] = NULL;
+        return ret;
 }
 
 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
diff --git a/kex.h b/kex.h
index 54134221f..8758804c5 100644
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: kex.h,v 1.21 2001/04/04 14:34:58 markus Exp $ */
+/*      $OpenBSD: kex.h,v 1.22 2001/04/04 20:25:37 markus Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -95,7 +95,7 @@ struct Newkeys {
 struct Kex {
         u_char  *session_id;
         int     session_id_len;
-        Newkeys *keys[MODE_MAX];
+        Newkeys *newkeys[MODE_MAX];
         int     we_need;
         int     server;
         char    *name;
@@ -103,7 +103,7 @@ struct Kex {
         int     kex_type;
         Buffer  my;
         Buffer  peer;
-        int     newkeys;
+        int     done;
         int     flags;
         char    *client_version_string;
         char    *server_version_string;
diff --git a/serverloop.c b/serverloop.c
index 4ae02fd10..ab7472b77 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -35,7 +35,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: serverloop.c,v 1.56 2001/04/04 14:34:58 markus Exp $");
+RCSID("$OpenBSD: serverloop.c,v 1.57 2001/04/04 20:25:37 markus Exp $");
 
 #include "xmalloc.h"
 #include "packet.h"
@@ -194,7 +194,7 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 retry_select:
 
         /* Allocate and update select() masks for channel descriptors. */
-        channel_prepare_select(readsetp, writesetp, maxfdp);
+        channel_prepare_select(readsetp, writesetp, maxfdp, 0);
 
         if (compat20) {
                 /* wrong: bad condition XXX */
diff --git a/sshconnect2.c b/sshconnect2.c
index 2f26aa569..918ab38e8 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.65 2001/04/04 14:34:58 markus Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.66 2001/04/04 20:25:38 markus Exp $");
 
 #include <openssl/bn.h>
 #include <openssl/md5.h>
@@ -119,7 +119,7 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
 
         xxx_kex = kex;
 
-        dispatch_run(DISPATCH_BLOCK, &kex->newkeys, kex);
+        dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 
         session_id2 = kex->session_id;
         session_id2_len = kex->session_id_len;
diff --git a/sshd.c b/sshd.c
index ea29e75ac..5b5928858 100644
--- a/sshd.c
+++ b/sshd.c
@@ -40,7 +40,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.189 2001/04/04 14:34:58 markus Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.190 2001/04/04 20:25:38 markus Exp $");
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
@@ -1437,7 +1437,7 @@ do_ssh2_kex(void)
 
         xxx_kex = kex;
 
-        dispatch_run(DISPATCH_BLOCK, &kex->newkeys, kex);
+        dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
 
         session_id2 = kex->session_id;
         session_id2_len = kex->session_id_len;