UPDATED PATCH:

Attached are a revised set of SSL patches.  Many of these patches
are motivated by security concerns, it's not just bug fixes.  The key
differences (from stock 7.2.1) are:

*) almost all code that directly uses the OpenSSL library is in two
   new files,

     src/interfaces/libpq/fe-ssl.c
     src/backend/postmaster/be-ssl.c

   in the long run, it would be nice to merge these two files.

*) the legacy code to read and write network data have been
   encapsulated into read_SSL() and write_SSL().  These functions
   should probably be renamed - they handle both SSL and non-SSL
   cases.

   the remaining code should eliminate the problems identified
   earlier, albeit not very cleanly.

*) both front- and back-ends will send a SSL shutdown via the
   new close_SSL() function.  This is necessary for sessions to
   work properly.

   (Sessions are not yet fully supported, but by cleanly closing
   the SSL connection instead of just sending a TCP FIN packet
   other SSL tools will be much happier.)

*) The client certificate and key are now expected in a subdirectory
   of the user's home directory.  Specifically,

	- the directory .postgresql must be owned by the user, and
	  allow no access by 'group' or 'other.'

	- the file .postgresql/postgresql.crt must be a regular file
	  owned by the user.

	- the file .postgresql/postgresql.key must be a regular file
	  owned by the user, and allow no access by 'group' or 'other'.

   At the current time encrypted private keys are not supported.
   There should also be a way to support multiple client certs/keys.

*) the front-end performs minimal validation of the back-end cert.
   Self-signed certs are permitted, but the common name *must*
   match the hostname used by the front-end.  (The cert itself
   should always use a fully qualified domain name (FDQN) in its
   common name field.)

   This means that

	  psql -h eris db

   will fail, but

	  psql -h eris.example.com db

   will succeed.  At the current time this must be an exact match;
   future patches may support any FQDN that resolves to the address
   returned by getpeername(2).

   Another common "problem" is expiring certs.  For now, it may be
   a good idea to use a very-long-lived self-signed cert.

   As a compile-time option, the front-end can specify a file
   containing valid root certificates, but it is not yet required.

*) the back-end performs minimal validation of the client cert.
   It allows self-signed certs.  It checks for expiration.  It
   supports a compile-time option specifying a file containing
   valid root certificates.

*) both front- and back-ends default to TLSv1, not SSLv3/SSLv2.

*) both front- and back-ends support DSA keys.  DSA keys are
   moderately more expensive on startup, but many people consider
   them preferable than RSA keys.  (E.g., SSH2 prefers DSA keys.)

*) if /dev/urandom exists, both client and server will read 16k
   of randomization data from it.

*) the server can read empheral DH parameters from the files

     $DataDir/dh512.pem
     $DataDir/dh1024.pem
     $DataDir/dh2048.pem
     $DataDir/dh4096.pem

   if none are provided, the server will default to hardcoded
   parameter files provided by the OpenSSL project.

Remaining tasks:

*) the select() clauses need to be revisited - the SSL abstraction
   layer may need to absorb more of the current code to avoid rare
   deadlock conditions.  This also touches on a true solution to
   the pg_eof() problem.

*) the SIGPIPE signal handler may need to be revisited.

*) support encrypted private keys.

*) sessions are not yet fully supported.  (SSL sessions can span
   multiple "connections," and allow the client and server to avoid
   costly renegotiations.)

*) makecert - a script that creates back-end certs.

*) pgkeygen - a tool that creates front-end certs.

*) the whole protocol issue, SASL, etc.

 *) certs are fully validated - valid root certs must be available.
    This is a hassle, but it means that you *can* trust the identity
    of the server.

 *) the client library can handle hardcoded root certificates, to
    avoid the need to copy these files.

 *) host name of server cert must resolve to IP address, or be a
    recognized alias.  This is more liberal than the previous
    iteration.

 *) the number of bytes transferred is tracked, and the session
    key is periodically renegotiated.

 *) basic cert generation scripts (mkcert.sh, pgkeygen.sh).  The
    configuration files have reasonable defaults for each type
    of use.

Bear Giles

3 files changed, 376 insertions, 17 deletions

diff --git a/src/backend/libpq/Makefile b/src/backend/libpq/Makefile
index 87f00e68ce6..cc4f750a7d6 100644
--- a/src/backend/libpq/Makefile
+++ b/src/backend/libpq/Makefile
@@ -4,7 +4,7 @@
 #    Makefile for libpq subsystem (backend half of libpq interface)
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/backend/libpq/Makefile,v 1.32 2002/06/14 04:09:36 momjian Exp $
+#    $Header: /cvsroot/pgsql/src/backend/libpq/Makefile,v 1.33 2002/06/14 04:23:17 momjian Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -14,7 +14,8 @@ include $(top_builddir)/src/Makefile.global
 
 # be-fsstubs is here for historical reasons, probably belongs elsewhere
 
-OBJS = be-fsstubs.o auth.o crypt.o hba.o md5.o pqcomm.o pqformat.o pqsignal.o
+OBJS = be-fsstubs.o be-secure.o auth.o crypt.o hba.o md5.o pqcomm.o \
+	pqformat.o pqsignal.o
 
 
 all: SUBSYS.o
diff --git a/src/backend/libpq/be-secure.c b/src/backend/libpq/be-secure.c
new file mode 100644
index 00000000000..6501882e4a5
--- /dev/null
+++ b/src/backend/libpq/be-secure.c
@@ -0,0 +1,365 @@
+/*-------------------------------------------------------------------------
+ *
+ * be-connect.c
+ *	  functions related to setting up a secure connection to the frontend.
+ *	  Secure connections are expected to provide confidentiality,
+ *	  message integrity and endpoint authentication.
+ *
+ *
+ * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/be-secure.c,v 1.1 2002/06/14 04:23:17 momjian Exp $
+ *	  
+ * PATCH LEVEL
+ *	  milestone 1: fix basic coding errors
+ *	  [*] existing SSL code pulled out of existing files.
+ *	  [*] SSL_get_error() after SSL_read() and SSL_write(),
+ *	      SSL_shutdown(), default to TLSv1.
+ *	
+ *	  milestone 2: provide endpoint authentication (server)
+ *	  [*] client verifies server cert
+ *	  [*] client verifies server hostname
+ *
+ *	  milestone 3: improve confidentially, support perfect forward secrecy
+ *	  [ ] use 'random' file, read from '/dev/urandom?'
+ *	  [ ] emphermal DH keys, default values
+ *	  [ ] periodic renegotiation
+ *
+ *	  milestone 4: provide endpoint authentication (client)
+ *	  [ ] server verifies client certificates
+ *
+ *	  milestone 5: provide informational callbacks
+ *	  [ ] provide informational callbacks
+ *
+ *	  other changes
+ *	  [ ] tcp-wrappers
+ *	  [ ] more informative psql
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <sys/types.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include "libpq/libpq.h"
+#include "libpq/pqsignal.h"
+#include "miscadmin.h"
+
+#ifdef WIN32
+#include "win32.h"
+#else
+#include <sys/socket.h>
+#include <unistd.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+#include <arpa/inet.h>
+#endif
+
+
+#ifndef HAVE_STRDUP
+#include "strdup.h"
+#endif
+
+#ifdef USE_SSL
+#include <openssl/ssl.h>
+#include <openssl/e_os.h>
+#endif
+
+extern void ExitPostmaster(int);
+extern void postmaster_error(const char *fmt,...);
+
+int secure_initialize(void);
+void secure_destroy(void);
+int secure_open_server(Port *);
+void secure_close(Port *);
+ssize_t secure_read(Port *, void *ptr, size_t len);
+ssize_t secure_write(Port *, const void *ptr, size_t len);
+
+#ifdef USE_SSL
+static int initialize_SSL(void);
+static void destroy_SSL(void);
+static int open_server_SSL(Port *);
+static void close_SSL(Port *);
+static const char *SSLerrmessage(void);
+#endif
+
+#ifdef USE_SSL
+static SSL_CTX *SSL_context = NULL;
+#endif
+
+/* ------------------------------------------------------------ */
+/*           Procedures common to all secure sessions           */
+/* ------------------------------------------------------------ */
+
+/*
+ *	Initialize global context
+ */
+int
+secure_initialize (void)
+{
+	int r = 0;
+
+#ifdef USE_SSL
+	r = initialize_SSL();
+#endif
+
+	return r;
+}
+
+/*
+ *	Destroy global context
+ */
+void
+secure_destroy (void)
+{
+#ifdef USE_SSL
+	destroy_SSL();
+#endif
+}
+
+/*
+ *	Attempt to negotiate secure session.
+ */
+int 
+secure_open_server (Port *port)
+{
+	int r = 0;
+
+#ifdef USE_SSL
+	r = open_server_SSL(port);
+#endif
+
+	return r;
+}
+
+/*
+ *	Close secure session.
+ */
+void
+secure_close (Port *port)
+{
+#ifdef USE_SSL
+	if (port->ssl)
+		close_SSL(port);
+#endif
+}
+
+/*
+ *	Read data from a secure connection.
+ */
+ssize_t
+secure_read (Port *port, void *ptr, size_t len)
+{
+	ssize_t n;
+
+#ifdef USE_SSL
+	if (port->ssl)
+	{
+		n = SSL_read(port->ssl, ptr, len);
+		switch (SSL_get_error(port->ssl, n))
+		{
+		case SSL_ERROR_NONE:
+			break;
+		case SSL_ERROR_WANT_READ:
+			break;
+		case SSL_ERROR_SYSCALL:
+			errno = get_last_socket_error();
+			elog(ERROR, "SSL SYSCALL error: %s", strerror(errno));
+			break;
+		case SSL_ERROR_SSL:
+			elog(ERROR, "SSL error: %s", SSLerrmessage());
+			/* fall through */
+		case SSL_ERROR_ZERO_RETURN:
+			secure_close(port);
+			errno = ECONNRESET;
+			n = -1;
+			break;
+		}
+	}
+	else
+#endif
+	n = recv(port->sock, ptr, len, 0);
+
+	return n;
+}
+
+/*
+ *	Write data to a secure connection.
+ */
+ssize_t
+secure_write (Port *port, const void *ptr, size_t len)
+{
+	ssize_t n;
+
+#ifndef WIN32
+	pqsigfunc oldsighandler = pqsignal(SIGPIPE, SIG_IGN);
+#endif
+
+#ifdef USE_SSL
+	if (port->ssl)
+	{
+		n = SSL_write(port->ssl, ptr, len);
+		switch (SSL_get_error(port->ssl, n))
+		{
+		case SSL_ERROR_NONE:
+			break;
+		case SSL_ERROR_WANT_WRITE:
+			break;
+		case SSL_ERROR_SYSCALL:
+			errno = get_last_socket_error();
+			elog(ERROR, "SSL SYSCALL error: %s", strerror(errno));
+			break;
+		case SSL_ERROR_SSL:
+			elog(ERROR, "SSL error: %s", SSLerrmessage());
+			/* fall through */
+		case SSL_ERROR_ZERO_RETURN:
+			secure_close(port);
+			errno = ECONNRESET;
+			n = -1;
+			break;
+		}
+	}
+	else
+#endif
+	n = send(port->sock, ptr, len, 0);
+
+#ifndef WIN32
+	pqsignal(SIGPIPE, oldsighandler);
+#endif
+
+	return n;
+}
+
+/* ------------------------------------------------------------ */
+/*                        SSL specific code                     */
+/* ------------------------------------------------------------ */
+#ifdef USE_SSL
+/*
+ *	Initialize global SSL context.
+ */
+static int
+initialize_SSL (void)
+{
+	char fnbuf[2048];
+
+	if (!SSL_context)
+	{
+		SSL_library_init();
+		SSL_load_error_strings();
+		SSL_context = SSL_CTX_new(TLSv1_method());
+		if (!SSL_context)
+		{
+			postmaster_error("failed to create SSL context: %s",
+							 SSLerrmessage());
+			ExitPostmaster(1);
+		}
+
+		/*
+		 *	Load and verify certificate and private key
+		 */
+		snprintf(fnbuf, sizeof(fnbuf), "%s/server.crt", DataDir);
+		if (!SSL_CTX_use_certificate_file(SSL_context, fnbuf, SSL_FILETYPE_PEM))
+		{
+			postmaster_error("failed to load server certificate (%s): %s",
+							 fnbuf, SSLerrmessage());
+			ExitPostmaster(1);
+		}
+		snprintf(fnbuf, sizeof(fnbuf), "%s/server.key", DataDir);
+		if (!SSL_CTX_use_PrivateKey_file(SSL_context, fnbuf, SSL_FILETYPE_PEM))
+		{
+			postmaster_error("failed to load private key file (%s): %s",
+							 fnbuf, SSLerrmessage());
+			ExitPostmaster(1);
+		}
+		if (!SSL_CTX_check_private_key(SSL_context))
+		{
+			postmaster_error("check of private key failed: %s",
+							 SSLerrmessage());
+			ExitPostmaster(1);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ *	Destroy global SSL context.
+ */
+static void
+destroy_SSL (void)
+{
+	if (SSL_context)
+	{
+		SSL_CTX_free(SSL_context);
+		SSL_context = NULL;
+	}
+}
+
+/*
+ *	Attempt to negotiate SSL connection.
+ */
+static int
+open_server_SSL (Port *port)
+{
+	if (!(port->ssl = SSL_new(SSL_context)) ||
+		!SSL_set_fd(port->ssl, port->sock) ||
+		SSL_accept(port->ssl) <= 0)
+	{
+		elog(ERROR, "failed to initialize SSL connection: %s", SSLerrmessage());
+		close_SSL(port);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ *	Close SSL connection.
+ */
+static void
+close_SSL (Port *port)
+{
+	if (port->ssl)
+	{
+		SSL_shutdown(port->ssl);
+		SSL_free(port->ssl);
+		port->ssl = NULL;
+	}
+}
+
+/*
+ * Obtain reason string for last SSL error
+ *
+ * Some caution is needed here since ERR_reason_error_string will
+ * return NULL if it doesn't recognize the error code.  We don't
+ * want to return NULL ever.
+ */
+static const char *
+SSLerrmessage(void)
+{
+	unsigned long	errcode;
+	const char	   *errreason;
+	static char		errbuf[32];
+
+	errcode = ERR_get_error();
+	if (errcode == 0)
+		return "No SSL error reported";
+	errreason = ERR_reason_error_string(errcode);
+	if (errreason != NULL)
+		return errreason;
+	snprintf(errbuf, sizeof(errbuf), "SSL error code %lu", errcode);
+	return errbuf;
+}
+
+#endif /* USE_SSL */
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index 4a71eb16155..ace32190c3f 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -29,7 +29,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$Id: pqcomm.c,v 1.135 2002/06/14 04:09:36 momjian Exp $
+ *	$Id: pqcomm.c,v 1.136 2002/06/14 04:23:17 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -81,6 +81,9 @@
 #include "miscadmin.h"
 #include "storage/ipc.h"
 
+extern void secure_close(Port *);
+extern ssize_t secure_read(Port *, void *, size_t);
+extern ssize_t secure_write(Port *, const void *, size_t);
 
 static void pq_close(void);
 
@@ -138,6 +141,7 @@ pq_close(void)
 {
 	if (MyProcPort != NULL)
 	{
+		secure_close(MyProcPort);
 		close(MyProcPort->sock);
 		/* make sure any subsequent attempts to do I/O fail cleanly */
 		MyProcPort->sock = -1;
@@ -457,14 +461,8 @@ pq_recvbuf(void)
 	{
 		int			r;
 
-#ifdef USE_SSL
-		if (MyProcPort->ssl)
-			r = SSL_read(MyProcPort->ssl, PqRecvBuffer + PqRecvLength,
-						 PQ_BUFFER_SIZE - PqRecvLength);
-		else
-#endif
-			r = recv(MyProcPort->sock, PqRecvBuffer + PqRecvLength,
-					 PQ_BUFFER_SIZE - PqRecvLength, 0);
+		r = secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
+						PQ_BUFFER_SIZE - PqRecvLength);
 
 		if (r < 0)
 		{
@@ -651,12 +649,7 @@ pq_flush(void)
 	{
 		int			r;
 
-#ifdef USE_SSL
-		if (MyProcPort->ssl)
-			r = SSL_write(MyProcPort->ssl, bufptr, bufend - bufptr);
-		else
-#endif
-			r = send(MyProcPort->sock, bufptr, bufend - bufptr, 0);
+		r = secure_write(MyProcPort, bufptr, bufend - bufptr);
 
 		if (r <= 0)
 		{