Allow initial connection (but no renegoriation) to servers which don't support
authorDr. Stephen Henson <steve@openssl.org>
Mon, 14 Dec 2009 13:56:04 +0000 (13:56 +0000)
committerDr. Stephen Henson <steve@openssl.org>
Mon, 14 Dec 2009 13:56:04 +0000 (13:56 +0000)
RI.

Reorganise RI checking code and handle some missing cases.

ssl/t1_lib.c

index 7f57636..bdbb806 100644 (file)
@@ -636,21 +636,11 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
        s->tlsext_status_type = -1;
 
        if (data >= (d+n-2))
-               {
-               if (s->new_session
-                       && !(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
-                       {
-                       /* We should always see one extension: the renegotiate extension */
-                       *al = SSL_AD_ILLEGAL_PARAMETER; /* is this the right alert? */
-                       SSLerr(SSL_F_SSL_PARSE_CLIENTHELLO_TLSEXT, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
-                       return 0;
-                       }
-               return 1;
-               }
+               goto ri_check;
        n2s(data,len);
 
        if (data > (d+n-len)) 
-               return 1;
+               goto ri_check;
 
        while (data <= (d+n-4))
                {
@@ -658,7 +648,7 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
                n2s(data,size);
 
                if (data+size > (d+n))
-                       return 1;
+                       goto ri_check;
 #if 0
                fprintf(stderr,"Received extension type %d size %d\n",type,size);
 #endif
@@ -971,17 +961,23 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
                /* session ticket processed earlier */
                data+=size;
                }
-  
-       if (s->new_session && !renegotiate_seen
-               && !(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
-               {
-               SSLerr(SSL_F_SSL_PARSE_CLIENTHELLO_TLSEXT, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
-               *al = SSL_AD_ILLEGAL_PARAMETER; /* is this the right alert? */
-               return 0;
-               }
                                
        *p = data;
+
+       ri_check:
+
+       /* Need RI if renegotiating */
+
+       if (!renegotiate_seen && s->new_session &&
+               !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
+               {
+               /* FIXME: Spec currently doesn't give alert to use */
+               *al = SSL_AD_ILLEGAL_PARAMETER;
+               SSLerr(SSL_F_SSL_PARSE_CLIENTHELLO_TLSEXT,
+                               SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
+               return 0;
+               }
+
        return 1;
        }
 
@@ -995,19 +991,7 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
        int renegotiate_seen = 0;
 
        if (data >= (d+n-2))
-               {
-               /* Because the client does not see any renegotiation during an
-                  attack, we must enforce this on all server hellos, even the
-                  first */
-               if (!(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
-                       {
-                       /* We should always see one extension: the renegotiate extension */
-                       *al = SSL_AD_ILLEGAL_PARAMETER; /* is this the right alert? */
-                       SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
-                       return 0;
-                       }
-               return 1;
-               }
+               goto ri_check;
 
        n2s(data,len);
 
@@ -1017,7 +1001,7 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
                n2s(data,size);
 
                if (data+size > (d+n))
-                       return 1;
+                       goto ri_check;
 
                if (s->tlsext_debug_cb)
                        s->tlsext_debug_cb(s, 1, type, data, size,
@@ -1141,14 +1125,6 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
                return 0;
                }
 
-       if (!renegotiate_seen
-               && !(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
-               {
-               *al = SSL_AD_ILLEGAL_PARAMETER; /* is this the right alert? */
-               SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
-               return 0;
-               }
-
        if (!s->hit && tlsext_servername == 1)
                {
                if (s->tlsext_hostname)
@@ -1171,6 +1147,26 @@ int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d, in
                }
 
        *p = data;
+
+       ri_check:
+
+       /* Determine if we need to see RI. Strictly speaking if we want to
+        * avoid an attack we should *always* see RI even on initial server
+        * hello because the client doesn't see any renegotiation during an
+        * attack. However this would mean we could not connect to any server
+        * which doesn't support RI so for the immediate future tolerate RI
+        * absence on initial connect only.
+        */
+       if (!renegotiate_seen && s->new_session &&
+               !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
+               {
+               /* FIXME: Spec currently doesn't give alert to use */
+               *al = SSL_AD_ILLEGAL_PARAMETER;
+               SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT,
+                               SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
+               return 0;
+               }
+
        return 1;
        }