Add an openssl_options main configuration option, to allow administrators to

shoot themselves in each foot in turn.  The default value is chosen to avoid
a change in behaviour, but since it is disabling a security countermeasure,
I'd like to change the default to be "no options".  Fixes: #994

3 files changed, 48 insertions, 3 deletions

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index b33edeb97..493c55445 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -1,4 +1,4 @@
-. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.74 2010/05/29 19:26:31 nm4 Exp $
+. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.75 2010/06/05 09:10:08 pdp Exp $
 .
 . /////////////////////////////////////////////////////////////////////////////
 . This is the primary source of the Exim Manual. It is an xfpt document that is
@@ -12392,6 +12392,7 @@ listed in more than one group.
 .row &%gnutls_require_mac%&          "control GnuTLS MAC algorithms"
 .row &%gnutls_require_protocols%&    "control GnuTLS protocols"
 .row &%gnutls_compat_mode%&          "use GnuTLS compatibility mode"
+.row &%openssl_options%&             "adjust OpenSSL compatibility options"
 .row &%tls_advertise_hosts%&         "advertise TLS to these hosts"
 .row &%tls_certificate%&             "location of server certificate"
 .row &%tls_crl%&                     "certificate revocation list"
@@ -14003,6 +14004,36 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)&
 transport driver.
 
 
+.option openssl_options main "string list" +dont_insert_empty_fragments
+.cindex "OpenSSL "compatibility options"
+This option allows an administrator to adjust the SSL options applied
+by OpenSSL to connections.  It is given as a space-separated list of items,
+each one to be +added or -subtracted from the current value.  The default
+value is one option which happens to have been set historically.  You can
+remove all options with:
+.code
+openssl_options = -all
+.endd
+This option is only available if Exim is built against OpenSSL.  The values
+available for this option vary according to the age of your OpenSSL install.
+The &"all"& value controls a subset of flags which are available, typically
+the bug workaround options.  The &'SSL_CTX_set_options'& man page will
+list the values known on your system and Exim should support all the
+&"bug workaround"& options and many of the &"modifying"& options.  The Exim
+names lose the leading &"SSL_OP_"& and are lower-cased.
+
+Note that adjusting the options can have severe impact upon the security of
+SSL as used by Exim.  It is possible to disable safety checks and shoot
+yourself in the foot in various unpleasant ways.  This option should not be
+adjusted lightly.  An unrecognised item will be detected at by invoking Exim
+with the &%-bV%& flag.
+
+An example:
+.code
+openssl_options = -all +microsoft_big_sslv3_buffer
+.endd
+
+
 .option oracle_servers main "string list" unset
 .cindex "Oracle" "server list"
 This option provides a list of Oracle servers and associated connection data,
diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 7b560e527..3ed3aa8c7 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -1,4 +1,4 @@
-$Cambridge: exim/doc/doc-txt/ChangeLog,v 1.616 2010/06/03 15:20:41 jetmore Exp $
+$Cambridge: exim/doc/doc-txt/ChangeLog,v 1.617 2010/06/05 09:10:09 pdp Exp $
 
 Change log file for Exim from version 4.21
 -------------------------------------------
@@ -14,6 +14,8 @@ PP/02 Include check_rfc2047_length in configure.default because we're seeing
 
 JJ/01 Added DISABLE_DKIM and comment to src/EDITME
 
+PP/03 Bugzilla 994: added openssl_options main configuration option.
+
 Exim version 4.72
 -----------------
 
diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff
index b42c0d07c..589bc5397 100644
--- a/doc/doc-txt/NewStuff
+++ b/doc/doc-txt/NewStuff
@@ -1,4 +1,4 @@
-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.165 2010/06/03 15:20:41 jetmore Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.166 2010/06/05 09:10:09 pdp Exp $
 
 New Features in Exim
 --------------------
@@ -9,6 +9,18 @@ test from the snapshots or the CVS before the documentation is updated. Once
 the documentation is updated, this file is reduced to a short list.
 
 
+Version 4.73
+------------
+
+ 1. A new main configuration option, "openssl_options", is available if Exim
+    is built with SSL support provided by OpenSSL.  The option allows
+    administrators to specify OpenSSL options to be used on connections;
+    typically this is to set bug compatibility features which the OpenSSL
+    developers have not enabled by default.  There may be security
+    consequences for certain options, so these should not be changed
+    frivolously.
+
+
 Version 4.72
 ------------