- markus@cvs.openbsd.org 2005/07/25 11:59:40

     [kex.c kex.h myproposal.h packet.c packet.h servconf.c session.c]
     [sshconnect2.c sshd.c sshd_config sshd_config.5]
     add a new compression method that delays compression until the user
     has been authenticated successfully and set compression to 'delayed'
     for sshd.
     this breaks older openssh clients (< 3.5) if they insist on
     compression, so you have to re-enable compression in sshd_config.
     ok djm@

diff --git a/ChangeLog b/ChangeLog
index 0418a7d7e9bb77f34e70cc066295a008a2947a9b..e0f7ffce35308dc6038c32715e6d286e9e5c6d9c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,15 @@
      [auth-passwd.c]
      auth_usercheck(3) can return NULL, so check for that. Report from
      mpech@. ok markus@
+   - markus@cvs.openbsd.org 2005/07/25 11:59:40
+     [kex.c kex.h myproposal.h packet.c packet.h servconf.c session.c]
+     [sshconnect2.c sshd.c sshd_config sshd_config.5]
+     add a new compression method that delays compression until the user
+     has been authenticated successfully and set compression to 'delayed'
+     for sshd.
+     this breaks older openssh clients (< 3.5) if they insist on
+     compression, so you have to re-enable compression in sshd_config.
+     ok djm@
 
 20050725
  - (dtucker) [configure.ac] Update zlib version check for CAN-2005-2096.

diff --git a/kex.c b/kex.c
index 06a3ad4ccd0cf313e8c2726d2de450be4a420b65..5dce335fe5f11d1fe3533425544a5760263011ef 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.63 2005/07/17 07:17:55 djm Exp $");
+RCSID("$OpenBSD: kex.c,v 1.64 2005/07/25 11:59:39 markus Exp $");
 
 #include <openssl/crypto.h>
 
@@ -275,10 +275,12 @@ choose_comp(Comp *comp, char *client, char *server)
        char *name = match_list(client, server, NULL);
        if (name == NULL)
                fatal("no matching comp found: client %s server %s", client, server);
-       if (strcmp(name, "zlib") == 0) {
-               comp->type = 1;
+       if (strcmp(name, "zlib@openssh.com") == 0) {
+               comp->type = COMP_DELAYED;
+       } else if (strcmp(name, "zlib") == 0) {
+               comp->type = COMP_ZLIB;
        } else if (strcmp(name, "none") == 0) {
-               comp->type = 0;
+               comp->type = COMP_NONE;
        } else {
                fatal("unsupported comp %s", name);
        }

diff --git a/kex.h b/kex.h
index 059d83cd5495ab3078560a8515fc7e46fbc0fb61..3024a27172eae078da61dbe08e705a3c1e03732f 100644 (file)
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kex.h,v 1.36 2005/06/17 02:44:32 djm Exp $    */
+/*     $OpenBSD: kex.h,v 1.37 2005/07/25 11:59:39 markus Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -35,6 +35,10 @@
 #define        KEX_DH14        "diffie-hellman-group14-sha1"
 #define        KEX_DHGEX       "diffie-hellman-group-exchange-sha1"
 
+#define COMP_NONE      0
+#define COMP_ZLIB      1
+#define COMP_DELAYED   2
+
 enum kex_init_proposals {
        PROPOSAL_KEX_ALGS,
        PROPOSAL_SERVER_HOST_KEY_ALGS,

diff --git a/myproposal.h b/myproposal.h
index 2edbe1624838aaafc4fccb0eb1fad53a3ab3041e..d8cba1caf818fc7da272781561a90399668ad2fd 100644 (file)
--- a/myproposal.h
+++ b/myproposal.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: myproposal.h,v 1.17 2005/05/23 23:32:46 djm Exp $     */
+/*     $OpenBSD: myproposal.h,v 1.18 2005/07/25 11:59:39 markus Exp $  */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -36,7 +36,7 @@
        "hmac-md5,hmac-sha1,hmac-ripemd160," \
        "hmac-ripemd160@openssh.com," \
        "hmac-sha1-96,hmac-md5-96"
-#define        KEX_DEFAULT_COMP        "none,zlib"
+#define        KEX_DEFAULT_COMP        "none,zlib@openssh.com,zlib"
 #define        KEX_DEFAULT_LANG        ""
 
 

diff --git a/packet.c b/packet.c
index d5b50f2f4ff7cb076be18b13b12e02ecd538d6f9..c855970fc7d151e1e31e52208ba916c1a71b4185 100644 (file)
--- a/packet.c
+++ b/packet.c
@@ -37,7 +37,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: packet.c,v 1.117 2005/06/17 02:44:32 djm Exp $");
+RCSID("$OpenBSD: packet.c,v 1.118 2005/07/25 11:59:39 markus Exp $");
 
 #include "openbsd-compat/sys-queue.h"
 
@@ -116,6 +116,12 @@ static int initialized = 0;
 /* Set to true if the connection is interactive. */
 static int interactive_mode = 0;
 
+/* Set to true if we are the server side. */
+static int server_side = 0;
+
+/* Set to true if we are authenticated. */
+static int after_authentication = 0;
+
 /* Session key information for Encryption and MAC */
 Newkeys *newkeys[MODE_MAX];
 static struct packet_state {
@@ -624,7 +630,9 @@ set_newkeys(int mode)
        /* Deleting the keys does not gain extra security */
        /* memset(enc->iv,  0, enc->block_size);
           memset(enc->key, 0, enc->key_len); */
-       if (comp->type != 0 && comp->enabled == 0) {
+       if ((comp->type == COMP_ZLIB ||
+           (comp->type == COMP_DELAYED && after_authentication)) &&
+           comp->enabled == 0) {
                packet_init_compression();
                if (mode == MODE_OUT)
                        buffer_compress_init_send(6);
@@ -644,6 +652,34 @@ set_newkeys(int mode)
                *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
 }
 
+/*
+ * Delayed compression for SSH2 is enabled after authentication:
+ * This happans on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
+ * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
+ */
+static void
+packet_enable_delayed_compress(void)
+{
+       Comp *comp = NULL;
+       int mode;
+
+       /*
+        * Remember that we are past the authentication step, so rekeying
+        * with COMP_DELAYED will turn on compression immediately.
+        */
+       after_authentication = 1;
+       for (mode = 0; mode < MODE_MAX; mode++) {
+               comp = &newkeys[mode]->comp;
+               if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
+                       if (mode == MODE_OUT)
+                               buffer_compress_init_send(6);
+                       else
+                               buffer_compress_init_recv();
+                       comp->enabled = 1;
+               }
+       }
+}
+
 /*
  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
  */
@@ -757,6 +793,8 @@ packet_send2_wrapped(void)
 
        if (type == SSH2_MSG_NEWKEYS)
                set_newkeys(MODE_OUT);
+       else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
+               packet_enable_delayed_compress();
 }
 
 static void
@@ -1099,6 +1137,8 @@ packet_read_poll2(u_int32_t *seqnr_p)
                packet_disconnect("Invalid ssh2 packet type: %d", type);
        if (type == SSH2_MSG_NEWKEYS)
                set_newkeys(MODE_IN);
+       else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
+               packet_enable_delayed_compress();
 #ifdef PACKET_DEBUG
        fprintf(stderr, "read/plain[%d]:\r\n", type);
        buffer_dump(&incoming_packet);
@@ -1524,3 +1564,15 @@ packet_set_rekey_limit(u_int32_t bytes)
 {
        rekey_limit = bytes;
 }
+
+void
+packet_set_server(void)
+{
+       server_side = 1;
+}
+
+void
+packet_set_authenticated(void)
+{
+       after_authentication = 1;
+}

diff --git a/packet.h b/packet.h
index 1ab6d8572a5afe74224b8d0837957cb823d90db3..8c23646aaae45c84c1bcdaa3f722254b66631e08 100644 (file)
--- a/packet.h
+++ b/packet.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: packet.h,v 1.42 2005/06/17 02:44:33 djm Exp $ */
+/*     $OpenBSD: packet.h,v 1.43 2005/07/25 11:59:40 markus Exp $      */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -30,6 +30,8 @@ u_int  packet_get_protocol_flags(void);
 void     packet_start_compression(int);
 void     packet_set_interactive(int);
 int      packet_is_interactive(void);
+void     packet_set_server(void);
+void     packet_set_authenticated(void);
 
 void     packet_start(u_char);
 void     packet_put_char(int ch);

diff --git a/servconf.c b/servconf.c
index deec167becb91080eeab8dcac70f685bfcaba2aa..7ef7b234e1fab86c9c1ba3711d760040ac439be3 100644 (file)
--- a/servconf.c
+++ b/servconf.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: servconf.c,v 1.142 2005/06/17 02:44:33 djm Exp $");
+RCSID("$OpenBSD: servconf.c,v 1.143 2005/07/25 11:59:40 markus Exp $");
 
 #include "ssh.h"
 #include "log.h"
@@ -201,7 +201,7 @@ fill_default_server_options(ServerOptions *options)
        if (options->use_login == -1)
                options->use_login = 0;
        if (options->compression == -1)
-               options->compression = 1;
+               options->compression = COMP_DELAYED;
        if (options->allow_tcp_forwarding == -1)
                options->allow_tcp_forwarding = 1;
        if (options->gateway_ports == -1)
@@ -725,7 +725,23 @@ parse_flag:
 
        case sCompression:
                intptr = &options->compression;
-               goto parse_flag;
+               arg = strdelim(&cp);
+               if (!arg || *arg == '\0')
+                       fatal("%s line %d: missing yes/no/delayed "
+                           "argument.", filename, linenum);
+               value = 0;      /* silence compiler */
+               if (strcmp(arg, "delayed") == 0)
+                       value = COMP_DELAYED;
+               else if (strcmp(arg, "yes") == 0)
+                       value = COMP_ZLIB;
+               else if (strcmp(arg, "no") == 0)
+                       value = COMP_NONE;
+               else
+                       fatal("%s line %d: Bad yes/no/delayed "
+                           "argument: %s", filename, linenum, arg);
+               if (*intptr == -1)
+                       *intptr = value;
+               break;
 
        case sGatewayPorts:
                intptr = &options->gateway_ports;

diff --git a/session.c b/session.c
index 171c239e241b7c607c7d181d7fbcfc6b6dc194c1..95084aec6c2158decd619bf64f655d2ed8a52a96 100644 (file)
--- a/session.c
+++ b/session.c
@@ -33,7 +33,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: session.c,v 1.185 2005/07/17 07:17:55 djm Exp $");
+RCSID("$OpenBSD: session.c,v 1.186 2005/07/25 11:59:40 markus Exp $");
 
 #include "ssh.h"
 #include "ssh1.h"
@@ -56,6 +56,7 @@ RCSID("$OpenBSD: session.c,v 1.185 2005/07/17 07:17:55 djm Exp $");
 #include "serverloop.h"
 #include "canohost.h"
 #include "session.h"
+#include "kex.h"
 #include "monitor_wrap.h"
 
 #if defined(KRB5) && defined(USE_AFS)
@@ -272,7 +273,7 @@ do_authenticated1(Authctxt *authctxt)
                                    compression_level);
                                break;
                        }
-                       if (!options.compression) {
+                       if (options.compression == COMP_NONE) {
                                debug2("compression disabled");
                                break;
                        }

diff --git a/sshconnect2.c b/sshconnect2.c
index 012ce2b423e6fc51129720eb018627bee6f289be..baee664ea5b938bed1abf23268acf72c9103700e 100644 (file)
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.140 2005/07/17 07:17:55 djm Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.141 2005/07/25 11:59:40 markus Exp $");
 
 #include "openbsd-compat/sys-queue.h"
 
@@ -101,10 +101,10 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
            compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
        if (options.compression) {
                myproposal[PROPOSAL_COMP_ALGS_CTOS] =
-               myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none";
+               myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
        } else {
                myproposal[PROPOSAL_COMP_ALGS_CTOS] =
-               myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib";
+               myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
        }
        if (options.macs != NULL) {
                myproposal[PROPOSAL_MAC_ALGS_CTOS] =

diff --git a/sshd.c b/sshd.c
index 40da375139ca14da499a3764e734615817f51dae..92aa9bbd21501e3b17657c869d227babf8778696 100644 (file)
--- a/sshd.c
+++ b/sshd.c
@@ -42,7 +42,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.311 2005/06/17 02:44:33 djm Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.312 2005/07/25 11:59:40 markus Exp $");
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
@@ -671,6 +671,12 @@ privsep_postauth(Authctxt *authctxt)
 
        /* It is safe now to apply the key state */
        monitor_apply_keystate(pmonitor);
+
+       /*
+        * Tell the packet layer that authentication was successful, since
+        * this information is not part of the key state.
+        */
+       packet_set_authenticated();
 }
 
 static char *
@@ -1621,6 +1627,7 @@ main(int ac, char **av)
         * not have a key.
         */
        packet_set_connection(sock_in, sock_out);
+       packet_set_server();
 
        /* Set SO_KEEPALIVE if requested. */
        if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
@@ -1988,10 +1995,14 @@ do_ssh2_kex(void)
                myproposal[PROPOSAL_MAC_ALGS_CTOS] =
                myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
        }
-       if (!options.compression) {
+       if (options.compression == COMP_NONE) {
                myproposal[PROPOSAL_COMP_ALGS_CTOS] =
                myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
+       } else if (options.compression == COMP_DELAYED) {
+               myproposal[PROPOSAL_COMP_ALGS_CTOS] =
+               myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
        }
+       
        myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
 
        /* start key exchange */

diff --git a/sshd_config b/sshd_config
index 2c3afb92030fa5da7a95a5f83ef9d87ff34a6794..1440c05ffcaf1e218c3523eda69626702f0be143 100644 (file)
--- a/sshd_config
+++ b/sshd_config
@@ -1,4 +1,4 @@
-#      $OpenBSD: sshd_config,v 1.71 2005/05/19 02:40:52 djm Exp $
+#      $OpenBSD: sshd_config,v 1.72 2005/07/25 11:59:40 markus Exp $
 
 # This is the sshd server system-wide configuration file.  See
 # sshd_config(5) for more information.
@@ -90,7 +90,7 @@
 #UseLogin no
 #UsePrivilegeSeparation yes
 #PermitUserEnvironment no
-#Compression yes
+#Compression delayed
 #ClientAliveInterval 0
 #ClientAliveCountMax 3
 #UseDNS yes

diff --git a/sshd_config.5 b/sshd_config.5
index cec2a2382bddea7c046b9f97965d27992f1801f5..048e8924e3bc508170e531cfadf936b366008795 100644 (file)
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.43 2005/05/23 23:32:46 djm Exp $
+.\" $OpenBSD: sshd_config.5,v 1.44 2005/07/25 11:59:40 markus Exp $
 .Dd September 25, 1999
 .Dt SSHD_CONFIG 5
 .Os
@@ -217,13 +217,15 @@ The default
 is 0, indicating that these messages will not be sent to the client.
 This option applies to protocol version 2 only.
 .It Cm Compression
-Specifies whether compression is allowed.
+Specifies whether compression is allowed, or delayed until
+the user has authenticated successfully.
 The argument must be
-.Dq yes
+.Dq yes ,
+.Dq delayed ,
 or
 .Dq no .
 The default is
-.Dq yes .
+.Dq delayed .
 .It Cm DenyGroups
 This keyword can be followed by a list of group name patterns, separated
 by spaces.