[Openvpn-devel,4/8] Move protocol option negotiation from push_prepare to new function

Message ID 20200709101603.11941-4-arne@rfc2549.org
State Accepted
Headers show
Series
  • [Openvpn-devel,1/8] Deprecate ncp-disable and add improved ncp to Changes.rst
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Commit Message

Arne Schwabe July 9, 2020, 10:15 a.m.
This clean ups the code and removes the surprising side effects
of preparing a push reply to also select protocol options.

We also remember if we have seen a push request without async
push. This improves reaction time if deferred auth is involved
like managment interface deferred auth.  The other benefit is
removing a number of ifdefs.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
---
 src/openvpn/forward.c |  4 +--
 src/openvpn/multi.c   | 81 ++++++++++++++++++++++++++++++++++++++++---
 src/openvpn/openvpn.h |  2 --
 src/openvpn/push.c    | 66 +++++------------------------------
 4 files changed, 88 insertions(+), 65 deletions(-)

Comments

tincanteksup July 9, 2020, 2:20 p.m. | #1
typo

On 09/07/2020 11:15, Arne Schwabe wrote:
> This clean ups the code and removes the surprising side effects
> of preparing a push reply to also select protocol options.
> 
> We also remember if we have seen a push request without async
> push. This improves reaction time if deferred auth is involved
> like managment interface deferred auth.  The other benefit is
> removing a number of ifdefs.
> 
> Signed-off-by: Arne Schwabe <arne@rfc2549.org>
> ---
>   src/openvpn/forward.c |  4 +--
>   src/openvpn/multi.c   | 81 ++++++++++++++++++++++++++++++++++++++++---
>   src/openvpn/openvpn.h |  2 --
>   src/openvpn/push.c    | 66 +++++------------------------------
>   4 files changed, 88 insertions(+), 65 deletions(-)
> 
> diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
> index 885cf126..5c4370a8 100644
> --- a/src/openvpn/forward.c
> +++ b/src/openvpn/forward.c
> @@ -1123,8 +1123,8 @@ process_incoming_link_part1(struct context *c, struct link_socket_info *lsi, boo
>           }
>   
>           /*
> -         * Drop non-TLS packet if client-connect script/plugin has not
> -         * yet succeeded.
> +         * Drop non-TLS packet if client-connect script/plugin and cipher selection
> +         * has not yet succeeded.
>            */
>           if (c->c2.context_auth != CAS_SUCCEEDED)
>           {
> diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
> index f1332c8d..f04c4c90 100644
> --- a/src/openvpn/multi.c
> +++ b/src/openvpn/multi.c
> @@ -824,8 +824,8 @@ multi_create_instance(struct multi_context *m, const struct mroute_addr *real)
>       mi->did_cid_hash = true;
>   #endif
>   
> -#ifdef ENABLE_ASYNC_PUSH
>       mi->context.c2.push_request_received = false;
> +#ifdef ENABLE_ASYNC_PUSH
>       mi->inotify_watch = -1;
>   #endif
>   
> @@ -1772,6 +1772,78 @@ multi_client_connect_setenv(struct multi_context *m,
>       gc_free(&gc);
>   }
>   
> +/**
> + * Calculates the options that depend on the client capabilities
> + * based on local options and available peer info
> + * - choosen cipher
> + * - peer id
> + */
> +static void
> +multi_client_set_protocol_options(struct context *c)
> +{
> +
> +    const char *optstr = NULL;
> +    struct tls_multi *tls_multi = c->c2.tls_multi;
> +    const char *const peer_info = tls_multi->peer_info;
> +    struct options *o = &c->options;
> +
> +    /* Send peer-id if client supports it */
> +    optstr = peer_info ? strstr(peer_info, "IV_PROTO=") : NULL;
> +    if (optstr)
> +    {
> +        int proto = 0;
> +        int r = sscanf(optstr, "IV_PROTO=%d", &proto);
> +        if ((r == 1) && (proto >= 2))
> +        {
> +            tls_multi->use_peer_id = true;
> +        }
> +    }
> +
> +    /* Select cipher if client supports Negotiable Crypto Parameters */
> +    if (o->ncp_enabled)
> +    {
> +        /* if we have already created our key, we cannot *change* our own
> +         * cipher -> so log the fact and push the "what we have now" cipher
> +         * (so the client is always told what we expect it to use)
> +         */
> +        const struct tls_session *session = &tls_multi->session[TM_ACTIVE];
> +        if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
> +        {
> +            msg( M_INFO, "PUSH: client wants to negotiate cipher (NCP), but "
> +                 "server has already generated data channel keys, "
> +                 "re-sending previously negotiated cipher '%s'",
> +                 o->ciphername );
> +        }
> +        else
> +        {
> +            /*
> +             * Push the first cipher from --ncp-ciphers to the client that
> +             * the client announces to be supporting.
> +             */
> +            char *push_cipher = ncp_get_best_cipher(o->ncp_ciphers, o->ciphername,
> +                                                    peer_info,
> +                                                    tls_multi->remote_ciphername,
> +                                                    &o->gc);
> +
> +            if (push_cipher)
> +            {
> +                o->ciphername = push_cipher;
> +            }
> +            else
> +            {
> +                struct gc_arena gc = gc_new();
> +                const char *peer_ciphers = tls_peer_ncp_list(peer_info, &gc);
> +                msg(M_INFO, "PUSH: No common cipher between server and client."
> +                    "Expect this connection not to work. "
> +                    "Server ncp-ciphers: '%s', client supported ciphers '%s'",
> +                    o->ncp_ciphers, peer_ciphers);
> +                gc_free(&gc);
> +            }
> +        }
> +    }
> +}
> +
> +
>   /*
>    * Called as soon as the SSL/TLS connection authenticates.
>    *
> @@ -2074,13 +2146,14 @@ script_failed:
>           /* set context-level authentication flag */
>           mi->context.c2.context_auth = CAS_SUCCEEDED;
>   
> -#ifdef ENABLE_ASYNC_PUSH
> -        /* authentication complete, send push reply */
> +        /* authentication complete, calculate dynamic client specific options */
> +        multi_client_set_protocol_options(&mi->context);
> +
> +        /* send push reply if ready*/
>           if (mi->context.c2.push_request_received)
>           {
>               process_incoming_push_request(&mi->context);
>           }
> -#endif
>       }
>       else
>       {
> diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
> index 4609af3e..a1308852 100644
> --- a/src/openvpn/openvpn.h
> +++ b/src/openvpn/openvpn.h
> @@ -432,9 +432,7 @@ struct context_2
>   #if P2MP
>   
>       /* --ifconfig endpoints to be pushed to client */
> -#ifdef ENABLE_ASYNC_PUSH
>       bool push_request_received;
> -#endif
>       bool push_ifconfig_defined;
>       time_t sent_push_reply_expiry;
>       in_addr_t push_ifconfig_local;
> diff --git a/src/openvpn/push.c b/src/openvpn/push.c
> index d74323db..92a28a14 100644
> --- a/src/openvpn/push.c
> +++ b/src/openvpn/push.c
> @@ -437,7 +437,7 @@ prepare_auth_token_push_reply(struct tls_multi *tls_multi, struct gc_arena *gc,
>   }
>   
>   /**
> - * Prepare push options, based on local options and available peer info.
> + * Prepare push options, based on local options
>    *
>    * @param context       context structure storing data for VPN tunnel
>    * @param gc            gc arena for allocating push options
> @@ -449,9 +449,7 @@ bool
>   prepare_push_reply(struct context *c, struct gc_arena *gc,
>                      struct push_list *push_list)
>   {
> -    const char *optstr = NULL;
>       struct tls_multi *tls_multi = c->c2.tls_multi;
> -    const char *const peer_info = tls_multi->peer_info;
>       struct options *o = &c->options;
>   
>       /* ipv6 */
> @@ -480,18 +478,10 @@ prepare_push_reply(struct context *c, struct gc_arena *gc,
>                                           0, gc));
>       }
>   
> -    /* Send peer-id if client supports it */
> -    optstr = peer_info ? strstr(peer_info, "IV_PROTO=") : NULL;
> -    if (optstr)
> +    if (tls_multi->use_peer_id)
>       {
> -        int proto = 0;
> -        int r = sscanf(optstr, "IV_PROTO=%d", &proto);
> -        if ((r == 1) && (proto >= 2))
> -        {
> -            push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
> -                            tls_multi->peer_id);
> -            tls_multi->use_peer_id = true;
> -        }
> +        push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
> +                        tls_multi->peer_id);
>       }
>       /*
>        * If server uses --auth-gen-token and we have an auth token
> @@ -499,47 +489,11 @@ prepare_push_reply(struct context *c, struct gc_arena *gc,
>        */
>       prepare_auth_token_push_reply(tls_multi, gc, push_list);
>   
> -    /* Push cipher if client supports Negotiable Crypto Parameters */
> -    if (o->ncp_enabled)
> -    {
> -        /* if we have already created our key, we cannot *change* our own
> -         * cipher -> so log the fact and push the "what we have now" cipher
> -         * (so the client is always told what we expect it to use)
> -         */
> -        const struct tls_session *session = &tls_multi->session[TM_ACTIVE];
> -        if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
> -        {
> -            msg( M_INFO, "PUSH: client wants to negotiate cipher (NCP), but "
> -                 "server has already generated data channel keys, "
> -                 "re-sending previously negotiated cipher '%s'",
> -                 o->ciphername );
> -        }
> -        else
> -        {
> -            /*
> -             * Push the first cipher from --ncp-ciphers to the client that
> -             * the client announces to be supporting.
> -             */
> -            char *push_cipher = ncp_get_best_cipher(o->ncp_ciphers, o->ciphername,
> -                                                    peer_info,
> -                                                    tls_multi->remote_ciphername,
> -                                                    &o->gc);
> -
> -            if (push_cipher)
> -            {
> -                o->ciphername = push_cipher;
> -            }
> -            else
> -            {
> -                const char *peer_ciphers = tls_peer_ncp_list(peer_info, gc);
> -                msg(M_INFO, "PUSH: No common cipher between server and client."
> -                    "Expect this connection not to work. "
> -                    "Server ncp-ciphers: '%s', client supported ciphers '%s'",
> -                    o->ncp_ciphers, peer_ciphers);
> -            }
> -        }
> -        push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
> -    }
> +    /*
> +     * Push the selected cipher, at this point the cipher has been
> +     * already negioated and been fixed

another negioated



> +     */
> +    push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
>   
>       return true;
>   }
> @@ -794,9 +748,7 @@ process_incoming_push_request(struct context *c)
>   {
>       int ret = PUSH_MSG_ERROR;
>   
> -#ifdef ENABLE_ASYNC_PUSH
>       c->c2.push_request_received = true;
> -#endif
>       if (tls_authentication_status(c->c2.tls_multi, 0) == TLS_AUTHENTICATION_FAILED || c->c2.context_auth == CAS_FAILED)
>       {
>           const char *client_reason = tls_client_reason(c->c2.tls_multi);
>
Gert Doering July 9, 2020, 6:35 p.m. | #2
Hi,

On Thu, Jul 09, 2020 at 12:15:59PM +0200, Arne Schwabe wrote:
> This clean ups the code and removes the surprising side effects
> of preparing a push reply to also select protocol options.
> 
> We also remember if we have seen a push request without async
> push. This improves reaction time if deferred auth is involved
> like managment interface deferred auth.  The other benefit is
> removing a number of ifdefs.
> 
> Signed-off-by: Arne Schwabe <arne@rfc2549.org>

I have tested this on the server side test torture program, and it 
reproduceably fails async-auth (with NCP, if that is relevant)

Jul  9 20:24:55 gentoo tun-udp-p2mp-global-authpam[9557]: cron2-freebsd-tc-amd64/2001:608:0:814::f000:21 Key [AF_INET6]2001:608:0:814::f000:21:28650 [0] not initialized (yet), dropping packet.

All other tests succeed.


Applying 5/8 on top of this makes the async auth test succeed again
(and normal connections as well, from a quick glance - the full test
is still running).

Let's discuss tomorrow how to proceed here.

gert
Gert Doering July 10, 2020, 3:22 p.m. | #3
Acked-by: Gert Doering <gert@greenie.muc.de>

Your patch has been applied to the master branch.

I have stared at the code, Antonio has stared at the code, and
it makes sense.  The test server says "but it breaks async auth",
so I've amended the commit message with a big fat NOTE that says 
"this breaks async auth, but we'll fix it next commit".

I have not tested async-push (it might be broken as well), but
we'll see to that next week when Lev is back.

commit 6344ea1218583d84baa986e6747e0c023d747245
Author: Arne Schwabe
Date:   Thu Jul 9 12:15:59 2020 +0200

     Move protocol option negotiation from push_prepare to new function

     Signed-off-by: Arne Schwabe <arne@rfc2549.org>
     Acked-by: Gert Doering <gert@greenie.muc.de>
     Message-Id: <20200709101603.11941-4-arne@rfc2549.org>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20255.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering
Gert Doering July 10, 2020, 3:24 p.m. | #4
*sigh* the commit ID in the previous mail was wrong, it was "before I
changed the commit message".  Here's the correct one.  Sorry.

commit 4f378ddb9932973965bb4931e85c991ddd86f7f0
Author: Arne Schwabe
Date:   Thu Jul 9 12:15:59 2020 +0200

     Move protocol option negotiation from push_prepare to new function

     Signed-off-by: Arne Schwabe <arne@rfc2549.org>
     Acked-by: Gert Doering <gert@greenie.muc.de>
     Message-Id: <20200709101603.11941-4-arne@rfc2549.org>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg20255.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering

Patch

diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
index 885cf126..5c4370a8 100644
--- a/src/openvpn/forward.c
+++ b/src/openvpn/forward.c
@@ -1123,8 +1123,8 @@  process_incoming_link_part1(struct context *c, struct link_socket_info *lsi, boo
         }
 
         /*
-         * Drop non-TLS packet if client-connect script/plugin has not
-         * yet succeeded.
+         * Drop non-TLS packet if client-connect script/plugin and cipher selection
+         * has not yet succeeded.
          */
         if (c->c2.context_auth != CAS_SUCCEEDED)
         {
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index f1332c8d..f04c4c90 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -824,8 +824,8 @@  multi_create_instance(struct multi_context *m, const struct mroute_addr *real)
     mi->did_cid_hash = true;
 #endif
 
-#ifdef ENABLE_ASYNC_PUSH
     mi->context.c2.push_request_received = false;
+#ifdef ENABLE_ASYNC_PUSH
     mi->inotify_watch = -1;
 #endif
 
@@ -1772,6 +1772,78 @@  multi_client_connect_setenv(struct multi_context *m,
     gc_free(&gc);
 }
 
+/**
+ * Calculates the options that depend on the client capabilities
+ * based on local options and available peer info
+ * - choosen cipher
+ * - peer id
+ */
+static void
+multi_client_set_protocol_options(struct context *c)
+{
+
+    const char *optstr = NULL;
+    struct tls_multi *tls_multi = c->c2.tls_multi;
+    const char *const peer_info = tls_multi->peer_info;
+    struct options *o = &c->options;
+
+    /* Send peer-id if client supports it */
+    optstr = peer_info ? strstr(peer_info, "IV_PROTO=") : NULL;
+    if (optstr)
+    {
+        int proto = 0;
+        int r = sscanf(optstr, "IV_PROTO=%d", &proto);
+        if ((r == 1) && (proto >= 2))
+        {
+            tls_multi->use_peer_id = true;
+        }
+    }
+
+    /* Select cipher if client supports Negotiable Crypto Parameters */
+    if (o->ncp_enabled)
+    {
+        /* if we have already created our key, we cannot *change* our own
+         * cipher -> so log the fact and push the "what we have now" cipher
+         * (so the client is always told what we expect it to use)
+         */
+        const struct tls_session *session = &tls_multi->session[TM_ACTIVE];
+        if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
+        {
+            msg( M_INFO, "PUSH: client wants to negotiate cipher (NCP), but "
+                 "server has already generated data channel keys, "
+                 "re-sending previously negotiated cipher '%s'",
+                 o->ciphername );
+        }
+        else
+        {
+            /*
+             * Push the first cipher from --ncp-ciphers to the client that
+             * the client announces to be supporting.
+             */
+            char *push_cipher = ncp_get_best_cipher(o->ncp_ciphers, o->ciphername,
+                                                    peer_info,
+                                                    tls_multi->remote_ciphername,
+                                                    &o->gc);
+
+            if (push_cipher)
+            {
+                o->ciphername = push_cipher;
+            }
+            else
+            {
+                struct gc_arena gc = gc_new();
+                const char *peer_ciphers = tls_peer_ncp_list(peer_info, &gc);
+                msg(M_INFO, "PUSH: No common cipher between server and client."
+                    "Expect this connection not to work. "
+                    "Server ncp-ciphers: '%s', client supported ciphers '%s'",
+                    o->ncp_ciphers, peer_ciphers);
+                gc_free(&gc);
+            }
+        }
+    }
+}
+
+
 /*
  * Called as soon as the SSL/TLS connection authenticates.
  *
@@ -2074,13 +2146,14 @@  script_failed:
         /* set context-level authentication flag */
         mi->context.c2.context_auth = CAS_SUCCEEDED;
 
-#ifdef ENABLE_ASYNC_PUSH
-        /* authentication complete, send push reply */
+        /* authentication complete, calculate dynamic client specific options */
+        multi_client_set_protocol_options(&mi->context);
+
+        /* send push reply if ready*/
         if (mi->context.c2.push_request_received)
         {
             process_incoming_push_request(&mi->context);
         }
-#endif
     }
     else
     {
diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
index 4609af3e..a1308852 100644
--- a/src/openvpn/openvpn.h
+++ b/src/openvpn/openvpn.h
@@ -432,9 +432,7 @@  struct context_2
 #if P2MP
 
     /* --ifconfig endpoints to be pushed to client */
-#ifdef ENABLE_ASYNC_PUSH
     bool push_request_received;
-#endif
     bool push_ifconfig_defined;
     time_t sent_push_reply_expiry;
     in_addr_t push_ifconfig_local;
diff --git a/src/openvpn/push.c b/src/openvpn/push.c
index d74323db..92a28a14 100644
--- a/src/openvpn/push.c
+++ b/src/openvpn/push.c
@@ -437,7 +437,7 @@  prepare_auth_token_push_reply(struct tls_multi *tls_multi, struct gc_arena *gc,
 }
 
 /**
- * Prepare push options, based on local options and available peer info.
+ * Prepare push options, based on local options
  *
  * @param context       context structure storing data for VPN tunnel
  * @param gc            gc arena for allocating push options
@@ -449,9 +449,7 @@  bool
 prepare_push_reply(struct context *c, struct gc_arena *gc,
                    struct push_list *push_list)
 {
-    const char *optstr = NULL;
     struct tls_multi *tls_multi = c->c2.tls_multi;
-    const char *const peer_info = tls_multi->peer_info;
     struct options *o = &c->options;
 
     /* ipv6 */
@@ -480,18 +478,10 @@  prepare_push_reply(struct context *c, struct gc_arena *gc,
                                         0, gc));
     }
 
-    /* Send peer-id if client supports it */
-    optstr = peer_info ? strstr(peer_info, "IV_PROTO=") : NULL;
-    if (optstr)
+    if (tls_multi->use_peer_id)
     {
-        int proto = 0;
-        int r = sscanf(optstr, "IV_PROTO=%d", &proto);
-        if ((r == 1) && (proto >= 2))
-        {
-            push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
-                            tls_multi->peer_id);
-            tls_multi->use_peer_id = true;
-        }
+        push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
+                        tls_multi->peer_id);
     }
     /*
      * If server uses --auth-gen-token and we have an auth token
@@ -499,47 +489,11 @@  prepare_push_reply(struct context *c, struct gc_arena *gc,
      */
     prepare_auth_token_push_reply(tls_multi, gc, push_list);
 
-    /* Push cipher if client supports Negotiable Crypto Parameters */
-    if (o->ncp_enabled)
-    {
-        /* if we have already created our key, we cannot *change* our own
-         * cipher -> so log the fact and push the "what we have now" cipher
-         * (so the client is always told what we expect it to use)
-         */
-        const struct tls_session *session = &tls_multi->session[TM_ACTIVE];
-        if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
-        {
-            msg( M_INFO, "PUSH: client wants to negotiate cipher (NCP), but "
-                 "server has already generated data channel keys, "
-                 "re-sending previously negotiated cipher '%s'",
-                 o->ciphername );
-        }
-        else
-        {
-            /*
-             * Push the first cipher from --ncp-ciphers to the client that
-             * the client announces to be supporting.
-             */
-            char *push_cipher = ncp_get_best_cipher(o->ncp_ciphers, o->ciphername,
-                                                    peer_info,
-                                                    tls_multi->remote_ciphername,
-                                                    &o->gc);
-
-            if (push_cipher)
-            {
-                o->ciphername = push_cipher;
-            }
-            else
-            {
-                const char *peer_ciphers = tls_peer_ncp_list(peer_info, gc);
-                msg(M_INFO, "PUSH: No common cipher between server and client."
-                    "Expect this connection not to work. "
-                    "Server ncp-ciphers: '%s', client supported ciphers '%s'",
-                    o->ncp_ciphers, peer_ciphers);
-            }
-        }
-        push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
-    }
+    /*
+     * Push the selected cipher, at this point the cipher has been
+     * already negioated and been fixed
+     */
+    push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
 
     return true;
 }
@@ -794,9 +748,7 @@  process_incoming_push_request(struct context *c)
 {
     int ret = PUSH_MSG_ERROR;
 
-#ifdef ENABLE_ASYNC_PUSH
     c->c2.push_request_received = true;
-#endif
     if (tls_authentication_status(c->c2.tls_multi, 0) == TLS_AUTHENTICATION_FAILED || c->c2.context_auth == CAS_FAILED)
     {
         const char *client_reason = tls_client_reason(c->c2.tls_multi);