Disable ssl renegotiation by default.

While postgres' use of SSL renegotiation is a good idea in theory, it
turned out to not work well in practice. The specification and openssl's
implementation of it have lead to several security issues. Postgres' use
of renegotiation also had its share of bugs.

Additionally OpenSSL has a bunch of bugs around renegotiation, reported
and open for years, that regularly lead to connections breaking with
obscure error messages. We tried increasingly complex workarounds to get
around these bugs, but we didn't find anything complete.

Since these connection breakages often lead to hard to debug problems,
e.g. spuriously failing base backups and significant latency spikes when
synchronous replication is used, we have decided to change the default
setting for ssl renegotiation to 0 (disabled) in the released
backbranches and remove it entirely in 9.5 and master..

Author: Michael Paquier, with changes by me
Discussion: 20150624144148[email protected]
Backpatch: 9.0-9.4; 9.5 and master get a different patch

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index c9276a36af05be84ad20887310ecceca2650a8fd..0dcfdf78595a54d568215bff5aa060e7f2ccf9ef 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -858,7 +858,7 @@ include 'filename'
         cryptanalysis when large amounts of traffic can be examined, but it
         also carries a large performance penalty. The sum of sent and received
         traffic is used to check the limit. If this parameter is set to 0,
-        renegotiation is disabled. The default is 512MB.
+        renegotiation is disabled. The default is 0.
        
        
         
@@ -870,6 +870,14 @@ include 'filename'
          disabled.
         
        
+
+       
+        
+         Due to bugs in OpenSSL enabling ssl renegotiation, by
+         configuring a non-zero ssl_renegotiation_limit, is likely
+         to lead to problems like long-lived connections breaking.
+        
+       
       
      
 

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 2b6527f012a9d96e8c8d1f14adcf1147fc297cd5..61cde68a6c32d915203a90e9cf5f5d4b43b02745 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2377,7 +2377,7 @@ static struct config_int ConfigureNamesInt[] =
            GUC_UNIT_KB,
        },
        &ssl_renegotiation_limit,
-       512 * 1024, 0, MAX_KILOBYTES,
+       0, 0, MAX_KILOBYTES,
        NULL, NULL, NULL
    },
 

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 12f1cbaa1f8c8982a77a1fc3e18a70e01a72f5a2..0bf2554a1d474cd7941361eaa9347edb8bc52846 100644 (file)
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -81,7 +81,7 @@
 #ssl = off             # (change requires restart)
 #ssl_ciphers = 'DEFAULT:!LOW:!EXP:!MD5:@STRENGTH'  # allowed SSL ciphers
                    # (change requires restart)
-#ssl_renegotiation_limit = 512MB   # amount of data between renegotiations
+#ssl_renegotiation_limit = 0       # amount of data between renegotiations
 #ssl_cert_file = 'server.crt'      # (change requires restart)
 #ssl_key_file = 'server.key'       # (change requires restart)
 #ssl_ca_file = ''          # (change requires restart)