OpenSSL fixes and backwards compat break.

Drop SSL_clear() after SSL_new() which causes protocol negotiation failures for TLS1.0 vs TLS1.1/1.2 in OpenSSL 1.0.1b.

Remove SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS (+dont_insert_empty_fragments) from default of openssl_options.

4 files changed, 27 insertions, 11 deletions

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index e719855f8..016f3f075 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -14333,16 +14333,12 @@ harm. This option overrides the &%pipe_as_creator%& option of the &(pipe)&
 transport driver.
 
 
-.option openssl_options main "string list" +dont_insert_empty_fragments
+.option openssl_options main "string list" unset
 .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
+each one to be +added or -subtracted from the current value.
+
 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
@@ -14354,12 +14350,19 @@ 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.
+adjusted lightly.  An unrecognised item will be detected at startup, by
+invoking Exim with the &%-bV%& flag.
+
+.new
+Historical note: prior to release 4.78, Exim defaulted this value to
+"+dont_insert_empty_fragments", which may still be needed for compatibility
+with some clients, but which lowers security by increasing exposure to
+some now infamous attacks.
+.wen
 
 An example:
 .code
-openssl_options = -all +microsoft_big_sslv3_buffer
+openssl_options = -all +microsoft_big_sslv3_buffer +dont_insert_empty_fragments
 .endd
 
 Possible options may include:
diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index b41783d71..a491cf973 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -69,6 +69,10 @@ PP/15 LDAP: Check for errors of TLS initialisation, to give correct
       diagnostics.
       Report and patch from Dmitry Banschikov.
 
+PP/16 Removed "dont_insert_empty_fragments" fron "openssl_options".
+      Removed SSL_clear() after SSL_new() which led to protocol negotiation
+      failures.  We appear to now support TLS1.1+ with Exim.
+
 
 Exim version 4.77
 -----------------
diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff
index b962b61a2..0aee33cec 100644
--- a/doc/doc-txt/NewStuff
+++ b/doc/doc-txt/NewStuff
@@ -33,6 +33,15 @@ Version 4.78
     into the DBM library.  Can be used with gsasl to access sasldb2 files as
     used by Cyrus SASL.
 
+ 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
+
+    Avoid release 1.0.1a if you can.  Note that the default value of
+    "openssl_options" is no longer "+dont_insert_empty_fragments", as that
+    increased susceptibility to attack.  This may still have interoperability
+    implications for very old clients (see version 4.31 change 37) but
+    administrators can choose to make the trade-off themselves and restore
+    compatibility at the cost of session security.
+
 
 Version 4.77
 ------------
diff --git a/doc/doc-txt/OptionLists.txt b/doc/doc-txt/OptionLists.txt
index 5313fd17c..b10f3f1aa 100644
--- a/doc/doc-txt/OptionLists.txt
+++ b/doc/doc-txt/OptionLists.txt
@@ -373,7 +373,7 @@ once                                 string*         unset         autoreply
 once_file_size                       integer         0             autoreply         3.20
 once_repeat                          time            0s            autoreply         2.95
 one_time                             boolean         false         redirect          4.00
-openssl_options                      string "+dont_insert_empty_fragments" main      4.73
+openssl_options                      string          unset         main              4.73 default to unset in 4.78
 optional                             boolean         false         iplookup          4.00
 oracle_servers                       string          unset         main              4.00
 owners                               string list     unset         redirect          4.00