Back-patch 9.4-era SSL renegotiation code into 9.3 and 9.2.

This back-patches 9.4 commits 31cf1a1a4, 86029b31e, and 36a3be654 into
the prior branches, along with relevant bits of b1aebbb6a and 7ce2a45ae.
We had foreseen doing this once the code was proven, but that never did
happen, probably because we got sufficiently fed up with renegotiation
to disable it by default.  However, we have to do something now because
the prior code doesn't even compile against OpenSSL 1.1.  Per discussion,
the best solution seems to be to make the older branches look like 9.4.

Discussion: https://postgr.es/m/20047.1492305247@sss.pgh.pa.us

diff --git a/src/backend/libpq/be-secure.c b/src/backend/libpq/be-secure.c
index 82a608dc5ba77fec809d6a21430b1a49c9b39b60..0dccd3f3287a2b140e5013ccb47d167719e3834e 100644 (file)
--- a/src/backend/libpq/be-secure.c
+++ b/src/backend/libpq/be-secure.c
@@ -102,6 +102,9 @@ char           *ssl_crl_file;
 int                    ssl_renegotiation_limit;
 
 #ifdef USE_SSL
+/* are we in the middle of a renegotiation? */
+static bool in_ssl_renegotiation = false;
+
 static SSL_CTX *SSL_context = NULL;
 static bool ssl_loaded_verify_locations = false;
 #endif
@@ -295,6 +298,7 @@ rloop:
                                                (errcode(ERRCODE_PROTOCOL_VIOLATION),
                                                 errmsg("unrecognized SSL error code: %d",
                                                                err)));
+                               errno = ECONNRESET;
                                n = -1;
                                break;
                }
@@ -326,29 +330,55 @@ secure_write(Port *port, void *ptr, size_t len)
                int                     err;
                unsigned long ecode;
 
-               if (ssl_renegotiation_limit && port->count > ssl_renegotiation_limit * 1024L)
+               /*
+                * If SSL renegotiations are enabled and we're getting close to the
+                * limit, start one now; but avoid it if there's one already in
+                * progress.  Request the renegotiation 1kB before the limit has
+                * actually expired.
+                */
+               if (ssl_renegotiation_limit && !in_ssl_renegotiation &&
+                       port->count > (ssl_renegotiation_limit - 1) * 1024L)
                {
+                       in_ssl_renegotiation = true;
+
+                       /*
+                        * The way we determine that a renegotiation has completed is by
+                        * observing OpenSSL's internal renegotiation counter.  Make sure
+                        * we start out at zero, and assume that the renegotiation is
+                        * complete when the counter advances.
+                        *
+                        * OpenSSL provides SSL_renegotiation_pending(), but this doesn't
+                        * seem to work in testing.
+                        */
+                       SSL_clear_num_renegotiations(port->ssl);
+
                        SSL_set_session_id_context(port->ssl, (void *) &SSL_context,
                                                                           sizeof(SSL_context));
                        if (SSL_renegotiate(port->ssl) <= 0)
                                ereport(COMMERROR,
                                                (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                                                errmsg("SSL renegotiation failure")));
-                       if (SSL_do_handshake(port->ssl) <= 0)
-                               ereport(COMMERROR,
-                                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                                                errmsg("SSL renegotiation failure")));
-                       if (port->ssl->state != SSL_ST_OK)
-                               ereport(COMMERROR,
-                                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                                                errmsg("SSL failed to send renegotiation request")));
-                       port->ssl->state |= SSL_ST_ACCEPT;
-                       SSL_do_handshake(port->ssl);
-                       if (port->ssl->state != SSL_ST_OK)
-                               ereport(COMMERROR,
-                                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                                                errmsg("SSL renegotiation failure")));
-                       port->count = 0;
+                                                errmsg("SSL failure during renegotiation start")));
+                       else
+                       {
+                               int                     retries;
+
+                               /*
+                                * A handshake can fail, so be prepared to retry it, but only
+                                * a few times.
+                                */
+                               for (retries = 0;; retries++)
+                               {
+                                       if (SSL_do_handshake(port->ssl) > 0)
+                                               break;  /* done */
+                                       ereport(COMMERROR,
+                                                       (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                                                        errmsg("SSL handshake failure on renegotiation, retrying")));
+                                       if (retries >= 20)
+                                               ereport(FATAL,
+                                                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                                                                errmsg("could not complete SSL handshake on renegotiation, too many failures")));
+                               }
+                       }
                }
 
 wloop:
@@ -393,9 +423,32 @@ wloop:
                                                (errcode(ERRCODE_PROTOCOL_VIOLATION),
                                                 errmsg("unrecognized SSL error code: %d",
                                                                err)));
+                               errno = ECONNRESET;
                                n = -1;
                                break;
                }
+
+               if (n >= 0)
+               {
+                       /* is renegotiation complete? */
+                       if (in_ssl_renegotiation &&
+                               SSL_num_renegotiations(port->ssl) >= 1)
+                       {
+                               in_ssl_renegotiation = false;
+                               port->count = 0;
+                       }
+
+                       /*
+                        * if renegotiation is still ongoing, and we've gone beyond the
+                        * limit, kill the connection now -- continuing to use it can be
+                        * considered a security problem.
+                        */
+                       if (in_ssl_renegotiation &&
+                               port->count > ssl_renegotiation_limit * 1024L)
+                               ereport(FATAL,
+                                               (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                                                errmsg("SSL failed to renegotiate connection before limit expired")));
+               }
        }
        else
 #endif

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 3ba3a0c6142b6601f639d2a3746bfe8ac12eb5fa..4c140ee3154fc452e792f87e9556af5a64de1af2 100644 (file)
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -553,16 +553,22 @@ prepare_for_client_read(void)
 
 /*
  * client_read_ended -- get out of the client-input state
+ *
+ * This is called just after low-level reads.  It must preserve errno!
  */
 void
 client_read_ended(void)
 {
        if (DoingCommandRead)
        {
+               int                     save_errno = errno;
+
                ImmediateInterruptOK = false;
 
                DisableNotifyInterrupt();
                DisableCatchupInterrupt();
+
+               errno = save_errno;
        }
 }