Allow renegotiation if SSL_OP_LEGACY_SERVER_CONNECT is set as well as

[openssl.git] / doc / ssl / SSL_CTX_set_options.pod

diff --git a/doc/ssl/SSL_CTX_set_options.pod b/doc/ssl/SSL_CTX_set_options.pod
index a878a6af6dc991316406eebf547d11a6659e924e..1abda2898e6a2c4a6f73d215b1115562d6110ea2 100644 (file)
--- a/doc/ssl/SSL_CTX_set_options.pod
+++ b/doc/ssl/SSL_CTX_set_options.pod
@@ -234,10 +234,10 @@ these options.
 =head1 SECURE RENEGOTIATION
 
 OpenSSL 0.9.8m and later always attempts to use secure renegotiation as
-described in draft-ietf-tls-renegotiation (FIXME: replace by RFC). This
-counters the prefix attack described in CVE-2009-3555 and elsewhere.
+described in RFC5746. This counters the prefix attack described in
+CVE-2009-3555 and elsewhere.
 
-The deprecated and highly broken SSLv2 protocol does not support secure
+The deprecated and highly broken SSLv2 protocol does not support
 renegotiation at all: its use is B<strongly> discouraged.
 
 This attack has far reaching consequences which application writers should be
@@ -276,10 +276,14 @@ was refused.
 =head2 Patched OpenSSL client and unpatched server.
 
 If the option B<SSL_OP_LEGACY_SERVER_CONNECT> is set then initial connections
-between patched OpenSSL clients and unpatched servers succeed. This option
-is currently set by default even though it has security implications: otherwise
-it would be impossible to connect to unpatched servers (i.e. all of them
-initially) and this is clearly not acceptable.
+and renegotiation between patched OpenSSL clients and unpatched servers
+succeeds.
+
+This option is currently set by default even though it has security
+implications: otherwise it would be impossible to connect to unpatched servers
+(i.e. all of them initially) and this is clearly not acceptable. Renegotiation
+is permitted because this does not add any additional security issues: during
+an attack clients do not see any renegotiations anyway.
 
 As more servers become patched the option B<SSL_OP_LEGACY_SERVER_CONNECT> will
 B<not> be set by default in a future version of OpenSSL.
@@ -292,10 +296,9 @@ unpatched servers (and thus avoid any security issues) should always B<clear>
 B<SSL_OP_LEGACY_SERVER_CONNECT> using SSL_CTX_clear_options() or
 SSL_clear_options().
 
-Renegotiation between a patched OpenSSL client and unpatched server follows
-the same scheme as between an unpatched client and a patched OpenSSL server:
-i.e. it is not permitted unless the option
-B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set.
+As in the previous case if the option
+B<SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION> is set then renegotiation
+B<always> succeeds.
 
 =head1 RETURN VALUES