[Openvpn-devel,v6,8/14] client-connect: Add CC_RET_DEFERRED and cope with deferred client-connect

Message ID 20200715141600.26610-1-arne@rfc2549.org
State Changes Requested
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Series
  • Untitled series #808
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Commit Message

Arne Schwabe July 15, 2020, 2:16 p.m.
This patch moves the state, that was previously tracked within the
multi_connection_established() function, into struct client_connect_state.  The
multi_connection_established() function can now be exited and re-entered as
many times as necessary - without losing the client-connect handling state.

The patch also adds the new return value CC_RET_DEFERRED which indicates that
the handler couldn't complete immediately, and needs to be called later.  At
that point multi_connection_established() will exit without indicating
completion.

Each client-connect handler now has an (optional) additional call-back:  The
call-back for handling the deferred case.  If the main call-back returns
CC_RET_DEFERRED, the next call to the handler will be through the deferred
call-back.

Signed-off-by: Fabian Knittel <fabian.knittel@lettink.de>

Patch V3: Use a static struct in multi_instance instead of using
          malloc/free and use two states (deffered with and without
          result) instead of one to eliminate the counter that was
          only tested for > 0.

Patch V5: Use new states in context_auth instead of the extra state
          that the patch series previously used.

Patch V6: Restructure code to make it a bit more readable, rebase on
          master.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
---
 src/openvpn/multi.c   | 168 +++++++++++++++++++++++++++++++-----------
 src/openvpn/multi.h   |  15 +++-
 src/openvpn/openvpn.h |   9 +++
 3 files changed, 147 insertions(+), 45 deletions(-)

Comments

Antonio Quartulli July 15, 2020, 2:59 p.m. | #1
Hi,

On 15/07/2020 16:16, Arne Schwabe wrote:
[CUT]

> -    multi_client_connect_early_setup(m, mi);
> +    handler = &client_connect_handlers[defer_state->cur_handler_index];
>  
> -    for (int i = 0; cc_succeeded && handlers[i]; i++)
> +    while (cc_succeeded && handler->main != NULL)
>      {
> -        ret = handlers[i](m, mi, &option_types_found);
> -        cc_succeeded = cc_check_return(&cc_succeeded_count, ret);
> +        enum client_connect_return ret;
> +        if (from_deferred)
> +        {
> +            ret = handler->deferred(m, mi, &(defer_state->option_types_found));
> +            from_deferred = false;
> +        }
> +        else
> +        {
> +            ret = handler->main(m, mi, &(defer_state->option_types_found));
> +        }
> +
> +        if (ret == CC_RET_SUCCEEDED)
> +        {
> +            /*
> +             * Remember that we already had at least one handler
> +             * returning a result should go to into deferred state
> +             */
> +            mi->context.c2.context_auth = CAS_PENDING_DEFERRED_PARTIAL;
> +        }
> +        else if (ret == CC_RET_SKIPPED)
> +        {
> +            /*
> +             * Move on with the next handler without modifying any
> +             * other state
> +             */
> +        }
> +        else if (ret == CC_RET_DEFERRED)
> +        {
> +            /*
> +             * we already set client_connect_status to DEFERRED_RESULT or
> +             * DEFERRED_NO_RESULT and increased index. We just return
> +             * from the function as having client_connect_status
> +             */
> +            return;
> +        }
> +        else if (ret == CC_RET_FAILED)
> +        {
> +            /*
> +             * One handler failed. We abort the chain and set the final
> +             * result to failed
> +             */
> +            cc_succeeded = false;
> +        }
> +        else
> +        {
> +            ASSERT(0);
> +        }
> +
> +        handler = &client_connect_handlers[defer_state->cur_handler_index];
> +        (defer_state->cur_handler_index)++;

shouldn't these 2 lines above be inverted?
(these parenthesis....)


Cheers,
tincanteksup July 15, 2020, 4:11 p.m. | #2
typo

On 15/07/2020 15:16, Arne Schwabe wrote:
> This patch moves the state, that was previously tracked within the
> multi_connection_established() function, into struct client_connect_state.  The
> multi_connection_established() function can now be exited and re-entered as
> many times as necessary - without losing the client-connect handling state.
> 
> The patch also adds the new return value CC_RET_DEFERRED which indicates that
> the handler couldn't complete immediately, and needs to be called later.  At
> that point multi_connection_established() will exit without indicating
> completion.
> 
> Each client-connect handler now has an (optional) additional call-back:  The
> call-back for handling the deferred case.  If the main call-back returns
> CC_RET_DEFERRED, the next call to the handler will be through the deferred
> call-back.
> 
> Signed-off-by: Fabian Knittel <fabian.knittel@lettink.de>
> 
> Patch V3: Use a static struct in multi_instance instead of using
>            malloc/free and use two states (deffered with and without

deffered -> deferred

>            result) instead of one to eliminate the counter that was
>            only tested for > 0.
> 
> Patch V5: Use new states in context_auth instead of the extra state
>            that the patch series previously used.
> 
> Patch V6: Restructure code to make it a bit more readable, rebase on
>            master.
> 
> Signed-off-by: Arne Schwabe <arne@rfc2549.org>
> ---


No further Red lines except for code and a contraction or two. eg: auth.
Arne Schwabe July 15, 2020, 5:40 p.m. | #3
Am 15.07.2020 um 16:59 schrieb Antonio Quartulli:
> Hi,
>
> On 15/07/2020 16:16, Arne Schwabe wrote:
> [CUT]
>
>> -    multi_client_connect_early_setup(m, mi);
>> +    handler = &client_connect_handlers[defer_state->cur_handler_index];
>>  
>> -    for (int i = 0; cc_succeeded && handlers[i]; i++)
>> +    while (cc_succeeded && handler->main != NULL)
>>      {
>> -        ret = handlers[i](m, mi, &option_types_found);
>> -        cc_succeeded = cc_check_return(&cc_succeeded_count, ret);
>> +        enum client_connect_return ret;
>> +        if (from_deferred)
>> +        {
>> +            ret = handler->deferred(m, mi, &(defer_state->option_types_found));
>> +            from_deferred = false;
>> +        }
>> +        else
>> +        {
>> +            ret = handler->main(m, mi, &(defer_state->option_types_found));
>> +        }
>> +
>> +        if (ret == CC_RET_SUCCEEDED)
>> +        {
>> +            /*
>> +             * Remember that we already had at least one handler
>> +             * returning a result should go to into deferred state
>> +             */
>> +            mi->context.c2.context_auth = CAS_PENDING_DEFERRED_PARTIAL;
>> +        }
>> +        else if (ret == CC_RET_SKIPPED)
>> +        {
>> +            /*
>> +             * Move on with the next handler without modifying any
>> +             * other state
>> +             */
>> +        }
>> +        else if (ret == CC_RET_DEFERRED)
>> +        {
>> +            /*
>> +             * we already set client_connect_status to DEFERRED_RESULT or
>> +             * DEFERRED_NO_RESULT and increased index. We just return
>> +             * from the function as having client_connect_status
>> +             */
>> +            return;
>> +        }
>> +        else if (ret == CC_RET_FAILED)
>> +        {
>> +            /*
>> +             * One handler failed. We abort the chain and set the final
>> +             * result to failed
>> +             */
>> +            cc_succeeded = false;
>> +        }
>> +        else
>> +        {
>> +            ASSERT(0);
>> +        }
>> +
>> +        handler = &client_connect_handlers[defer_state->cur_handler_index];
>> +        (defer_state->cur_handler_index)++;
> shouldn't these 2 lines above be inverted?
> (these parenthesis....)

Yeah :(


Arne

Patch

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 97b7df16..331891bc 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -2225,32 +2225,50 @@  multi_client_connect_source_ccd(struct multi_context *m,
     return ret;
 }
 
-static inline bool
-cc_check_return(int *cc_succeeded_count,
-                enum client_connect_return ret)
+typedef enum client_connect_return (*multi_client_connect_handler)
+    (struct multi_context *m, struct multi_instance *mi,
+    unsigned int *option_types_found);
+
+struct client_connect_handlers
+{
+    multi_client_connect_handler main;
+    multi_client_connect_handler deferred;
+};
+
+static enum client_connect_return
+multi_client_connect_fail(struct multi_context *m, struct multi_instance *mi,
+                          unsigned int *option_types_found)
 {
-    if (ret == CC_RET_SUCCEEDED)
+    /* Called null call-back.  This should never happen. */
+    return CC_RET_FAILED;
+}
+
+static const struct client_connect_handlers client_connect_handlers[] = {
     {
-        (*cc_succeeded_count)++;
-        return true;
-    }
-    else if (ret == CC_RET_FAILED)
+        .main = multi_client_connect_source_ccd,
+        .deferred = multi_client_connect_fail
+    },
     {
-        return false;
-    }
-    else if (ret == CC_RET_SKIPPED)
+        .main = multi_client_connect_call_plugin_v1,
+        .deferred = multi_client_connect_fail
+    },
     {
-        return true;
-    }
-    else
+        .main = multi_client_connect_call_plugin_v2,
+        .deferred = multi_client_connect_fail
+    },
+    {
+        .main = multi_client_connect_call_script,
+        .deferred = multi_client_connect_fail
+    },
     {
-        ASSERT(0);
+        .main = multi_client_connect_mda,
+        .deferred = multi_client_connect_fail
+    },
+    {
+        .main = NULL,
+        .deferred = NULL
     }
-}
-
-typedef enum client_connect_return (*multi_client_connect_handler)
-    (struct multi_context *m, struct multi_instance *mi,
-     unsigned int *option_types_found);
+};
 
 /*
  * Called as soon as the SSL/TLS connection is authenticated.
@@ -2280,27 +2298,81 @@  multi_connection_established(struct multi_context *m, struct multi_instance *mi)
         return;
     }
 
-        multi_client_connect_handler handlers[] = {
-            multi_client_connect_source_ccd,
-            multi_client_connect_call_plugin_v1,
-            multi_client_connect_call_plugin_v2,
-            multi_client_connect_call_script,
-            multi_client_connect_mda,
-            NULL
-        };
+    /* We are only called for the CAS_PENDING_x states, so we
+     * can ignore other states here */
+    bool from_deferred = (mi->context.c2.context_auth != CAS_PENDING);
 
-        unsigned int option_types_found = 0;
+    struct client_connect_defer_state *defer_state =
+        &(mi->client_connect_defer_state);
 
-    int cc_succeeded = true;     /* client connect script status */
-    int cc_succeeded_count = 0;
-    enum client_connect_return ret;
+    /* We are called for the first time */
+    if (!from_deferred)
+    {
+        defer_state->cur_handler_index = 0;
+        defer_state->option_types_found = 0;
+        /* Initially we have no handler that has returned a result */
+        mi->context.c2.context_auth = CAS_PENDING_DEFERRED;
+
+        multi_client_connect_early_setup(m, mi);
+    }
+
+    const struct client_connect_handlers *handler;
+    bool cc_succeeded = true;
 
-    multi_client_connect_early_setup(m, mi);
+    handler = &client_connect_handlers[defer_state->cur_handler_index];
 
-    for (int i = 0; cc_succeeded && handlers[i]; i++)
+    while (cc_succeeded && handler->main != NULL)
     {
-        ret = handlers[i](m, mi, &option_types_found);
-        cc_succeeded = cc_check_return(&cc_succeeded_count, ret);
+        enum client_connect_return ret;
+        if (from_deferred)
+        {
+            ret = handler->deferred(m, mi, &(defer_state->option_types_found));
+            from_deferred = false;
+        }
+        else
+        {
+            ret = handler->main(m, mi, &(defer_state->option_types_found));
+        }
+
+        if (ret == CC_RET_SUCCEEDED)
+        {
+            /*
+             * Remember that we already had at least one handler
+             * returning a result should go to into deferred state
+             */
+            mi->context.c2.context_auth = CAS_PENDING_DEFERRED_PARTIAL;
+        }
+        else if (ret == CC_RET_SKIPPED)
+        {
+            /*
+             * Move on with the next handler without modifying any
+             * other state
+             */
+        }
+        else if (ret == CC_RET_DEFERRED)
+        {
+            /*
+             * we already set client_connect_status to DEFERRED_RESULT or
+             * DEFERRED_NO_RESULT and increased index. We just return
+             * from the function as having client_connect_status
+             */
+            return;
+        }
+        else if (ret == CC_RET_FAILED)
+        {
+            /*
+             * One handler failed. We abort the chain and set the final
+             * result to failed
+             */
+            cc_succeeded = false;
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        handler = &client_connect_handlers[defer_state->cur_handler_index];
+        (defer_state->cur_handler_index)++;
     }
 
     /*
@@ -2312,18 +2384,26 @@  multi_connection_established(struct multi_context *m, struct multi_instance *mi)
         msg(D_MULTI_ERRORS, "MULTI: client has been rejected due to "
             "'disable' directive");
         cc_succeeded = false;
-        cc_succeeded_count = 0;
     }
 
     if (cc_succeeded)
     {
-        multi_client_connect_late_setup(m, mi, option_types_found);
+        multi_client_connect_late_setup(m, mi,
+                                        defer_state->option_types_found);
     }
     else
     {
-        /* set context-level authentication flag */
-        mi->context.c2.context_auth =
-            cc_succeeded_count ? CAS_PARTIAL : CAS_FAILED;
+        /* set context-level authentication flag to failed but remember
+         * if had a handler succeed (for cleanup) */
+        if (mi->context.c2.context_auth == CAS_PENDING_DEFERRED_PARTIAL)
+        {
+            mi->context.c2.context_auth = CAS_PARTIAL;
+        }
+        else
+        {
+            mi->context.c2.context_auth = CAS_FAILED;
+        }
+
     }
 
     /* increment number of current authenticated clients */
@@ -2624,7 +2704,7 @@  multi_process_post(struct multi_context *m, struct multi_instance *mi, const uns
         {
             /* connection is "established" when SSL/TLS key negotiation succeeds
              * and (if specified) auth user/pass succeeds */
-            if (mi->context.c2.context_auth == CAS_PENDING
+            if (is_cas_pending(mi->context.c2.context_auth)
                 && CONNECTION_ESTABLISHED(&mi->context))
             {
                 multi_connection_established(m, mi);
@@ -3579,7 +3659,7 @@  management_client_auth(void *arg,
         {
             if (auth)
             {
-                if (mi->context.c2.context_auth == CAS_PENDING)
+                if (is_cas_pending(mi->context.c2.context_auth))
                 {
                     set_cc_config(mi, cc_config);
                     cc_config_owned = false;
@@ -3591,7 +3671,7 @@  management_client_auth(void *arg,
                 {
                     msg(D_MULTI_LOW, "MULTI: connection rejected: %s, CLI:%s", reason, np(client_reason));
                 }
-                if (mi->context.c2.context_auth != CAS_PENDING)
+                if (!is_cas_pending(mi->context.c2.context_auth))
                 {
                     send_auth_failed(&mi->context, client_reason); /* mid-session reauth failed */
                     multi_schedule_context_wakeup(m, mi);
diff --git a/src/openvpn/multi.h b/src/openvpn/multi.h
index 1d30dcc6..11da0209 100644
--- a/src/openvpn/multi.h
+++ b/src/openvpn/multi.h
@@ -62,6 +62,18 @@  struct deferred_signal_schedule_entry
     struct timeval wakeup;
 };
 
+/**
+ * Detached client connection state.  This is the state that is tracked while
+ * the client connect hooks are executed.
+ */
+struct client_connect_defer_state
+{
+    /* Index of currently executed handler.  */
+    int cur_handler_index;
+    /* Remember which option classes where processed for delayed option
+     * handling. */
+    unsigned int option_types_found;
+};
 
 /**
  * Server-mode state structure for one single VPN tunnel.
@@ -108,7 +120,7 @@  struct multi_instance {
 
     struct context context;     /**< The context structure storing state
                                  *   for this VPN tunnel. */
-
+    struct client_connect_defer_state client_connect_defer_state;
 #ifdef ENABLE_ASYNC_PUSH
     int inotify_watch; /* watch descriptor for acf */
 #endif
@@ -195,6 +207,7 @@  enum client_connect_return
 {
     CC_RET_FAILED,
     CC_RET_SUCCEEDED,
+    CC_RET_DEFERRED,
     CC_RET_SKIPPED
 };
 
diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
index 7c469b01..ccc7f118 100644
--- a/src/openvpn/openvpn.h
+++ b/src/openvpn/openvpn.h
@@ -217,6 +217,8 @@  struct context_1
 enum client_connect_status {
     CAS_SUCCEEDED=0,
     CAS_PENDING,
+    CAS_PENDING_DEFERRED,
+    CAS_PENDING_DEFERRED_PARTIAL,   /**< at least handler succeeded, no result yet*/
     CAS_FAILED,
     CAS_PARTIAL,        /**< Variant of CAS_FAILED: at least one
                          * client-connect script/plugin succeeded
@@ -225,6 +227,13 @@  enum client_connect_status {
                          */
 };
 
+static inline bool
+is_cas_pending(enum client_connect_status cas)
+{
+    return cas == CAS_PENDING || cas == CAS_PENDING_DEFERRED
+           || cas == CAS_PENDING_DEFERRED_PARTIAL;
+}
+
 /**
  * Level 2 %context containing state that is reset on both \c SIGHUP and
  * \c SIGUSR1 restarts.