Fix multiple breakages in our support for SSL certificates.

doc/src/sgml/libpq.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.163 2004/09/23 13:31:09 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.164 2004/09/26 22:51:49 tgl Exp $
 -->
 
  <chapter id="libpq">
@@ -233,22 +233,13 @@ PGconn *PQconnectdb(const char *conninfo);
 
       <para>
        If <productname>PostgreSQL</> is compiled without SSL support,
-       using option <literal>require</> will cause an error, and
+       using option <literal>require</> will cause an error, while
        options <literal>allow</> and <literal>prefer</> will be
        tolerated but <application>libpq</> will be unable to negotiate
        an <acronym>SSL</>
        connection.<indexterm><primary>SSL</><secondary
        sortas="libpq">with libpq</></indexterm>
       </para>
-
-      <para>
-       Please note that <acronym>SSL</> support in libpq covers
-       encryption only.  It will not verify the validity of the
-       certificate presented by the server that you are connecting to,
-       nor verify that the hostname matches that of the server's
-       certificate.  Additionally, there is no support for client
-       certificates.
-      </para>
      </listitem>
     </varlistentry>
 
@@ -3688,6 +3679,41 @@ If the permissions are less strict than this, the file will be ignored.
 </para>
 </sect1>
 
+
+<sect1 id="libpq-ssl">
+<title>SSL Support</title>
+
+<indexterm zone="libpq-ssl">
+ <primary>SSL</primary>
+</indexterm>
+
+  <para>
+   <productname>PostgreSQL</> has native support for using
+   <acronym>SSL</> connections to encrypt client/server communications
+   for increased security. See <xref linkend="ssl-tcp"> for details
+   about the server-side <acronym>SSL</> functionality.
+  </para>
+
+  <para>
+   If the server demands a client certificate, 
+   <application>libpq</application>
+   will send the certificate stored in file
+   <filename>.postgresql/postgresql.crt</> within the user's home directory.
+   A matching private key file <filename>.postgresql/postgresql.key</>
+   must also be present, and must not be world-readable.
+  </para>
+
+  <para>
+   If the file <filename>.postgresql/root.crt</> is present in the user's
+   home directory,
+   <application>libpq</application> will use the certificate list stored
+   therein to verify the server's certificate.  The SSL connection will
+   fail if the server does not present a certificate; therefore, to
+   use this feature the server must also have a <filename>root.crt</> file.
+  </para>
+</sect1>
+
+
 <sect1 id="libpq-threading">
 <title>Behavior in Threaded Programs</title>
 

doc/src/sgml/runtime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.283 2004/09/23 13:15:57 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.284 2004/09/26 22:51:49 tgl Exp $
 -->
 
 <Chapter Id="runtime">
@@ -804,7 +804,7 @@ SET ENABLE_SEQSCAN TO OFF;
        <para>
         Enables <acronym>SSL</> connections. Please read
         <xref linkend="ssl-tcp"> before using this. The default
-        is off.
+        is off.  This parameter can only be set at server start.
        </para>
       </listitem>
      </varlistentry>
@@ -4324,8 +4324,8 @@ $ <userinput>kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid`</userinput
    The server will listen for both standard and <acronym>SSL</>
    connections on the same TCP port, and will negotiate with any
    connecting client on whether to use <acronym>SSL</>. See <xref
-   linkend="auth-pg-hba-conf"> about how to force the server to
-   require use of <acronym>SSL</> for certain connections.
+   linkend="auth-pg-hba-conf"> about how to set up the server to
+   require use of <acronym>SSL</> for some or all connections.
   </para>
 
   <para>
@@ -4361,20 +4361,24 @@ chmod og-rwx server.key
 
   <para>
    If verification of client certificates is required, place the
-   certificates of the <acronym>CA</acronym> you wish to check for in
+   certificates of the <acronym>CA</acronym>(s) you wish to check for in
    the file <filename>root.crt</filename> in the data directory.  When
    present, a client certificate will be requested from the client
-   making the connection and it must have been signed by one of the
-   certificates present in <filename>root.crt</filename>.  If no
-   certificate is presented, the connection will be allowed to proceed
-   anway.
+   during SSL connection startup, and it must have been signed by one of the
+   certificates present in <filename>root.crt</filename>.
   </para>
 
   <para>
-   The <filename>root.crt</filename> file is always checked for, and
-   its absence will be noted through a message in the log.  This is
-   merely an informative message that client certificates will not be
-   requested.
+   When the <filename>root.crt</filename> file is not present, client
+   certificates will not be requested or checked.  In this mode, SSL
+   provides communication security but not authentication.
+  </para>
+
+  <para>
+   The files <filename>server.key</>, <filename>server.crt</>,
+   and <filename>root.crt</filename> are only examined during server
+   start; so you must restart the server to make changes in them take
+   effect.
   </para>
  </sect1>
 

src/backend/libpq/be-secure.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/libpq/be-secure.c,v 1.50 2004/09/23 20:27:50 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/libpq/be-secure.c,v 1.51 2004/09/26 22:51:49 tgl Exp $
  *
  *	  Since the server static private key ($DataDir/server.key)
  *	  will normally be stored unencrypted so that the database
@@ -117,7 +117,6 @@ static const char *SSLerrmessage(void);
  *	(total in both directions) before we require renegotiation.
  */
 #define RENEGOTIATION_LIMIT (512 * 1024 * 1024)
-#define CA_PATH NULL
 
 static SSL_CTX *SSL_context = NULL;
 #endif
@@ -412,12 +411,12 @@ static DH  *
 load_dh_file(int keylength)
 {
 	FILE	   *fp;
-	char		fnbuf[2048];
+	char		fnbuf[MAXPGPATH];
 	DH		   *dh = NULL;
 	int			codes;
 
 	/* attempt to open file.  It's not an error if it doesn't exist. */
-	snprintf(fnbuf, sizeof fnbuf, "%s/dh%d.pem", DataDir, keylength);
+	snprintf(fnbuf, sizeof(fnbuf), "%s/dh%d.pem", DataDir, keylength);
 	if ((fp = fopen(fnbuf, "r")) == NULL)
 		return NULL;
 
@@ -694,20 +693,26 @@ initialize_SSL(void)
 	if (SSL_CTX_set_cipher_list(SSL_context, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH") != 1)
 		elog(FATAL, "could not set the cipher list (no valid ciphers available)");
 
-	/* accept client certificates, but don't require them. */
+	/*
+	 * Require and check client certificates only if we have a root.crt file.
+	 */
 	snprintf(fnbuf, sizeof(fnbuf), "%s/root.crt", DataDir);
-	if (!SSL_CTX_load_verify_locations(SSL_context, fnbuf, CA_PATH))
+	if (!SSL_CTX_load_verify_locations(SSL_context, fnbuf, NULL))
 	{
 		/* Not fatal - we do not require client certificates */
 		ereport(LOG,
 				(errmsg("could not load root certificate file \"%s\": %s",
 						fnbuf, SSLerrmessage()),
 				 errdetail("Will not verify client certificates.")));
-		return 0;
 	}
-	SSL_CTX_set_verify(SSL_context,
-					   SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE,
-					   verify_cb);
+	else
+	{
+		SSL_CTX_set_verify(SSL_context,
+						   (SSL_VERIFY_PEER |
+							SSL_VERIFY_FAIL_IF_NO_PEER_CERT |
+							SSL_VERIFY_CLIENT_ONCE),
+						   verify_cb);
+	}
 
 	return 0;
 }

src/interfaces/libpq/fe-secure.c

@@ -11,9 +11,11 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.51 2004/09/23 20:27:43 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.52 2004/09/26 22:51:49 tgl Exp $
  *
  * NOTES
+ *	  [ Most of these notes are wrong/obsolete, but perhaps not all ]
+ *
  *	  The client *requires* a valid server certificate.  Since
  *	  SSH tunnels provide anonymous confidentiality, the presumption
  *	  is that sites that want endpoint authentication will use the
@@ -527,7 +529,7 @@ verify_peer(PGconn *conn)
 	if (h == NULL)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-		libpq_gettext("could not get information about host (%s): %s\n"),
+		libpq_gettext("could not get information about host \"%s\": %s\n"),
 						  conn->peer_cn, hstrerror(h_errno));
 		return -1;
 	}
@@ -600,15 +602,15 @@ load_dh_file(int keylength)
 	struct passwd pwdstr;
 	struct passwd *pwd = NULL;
 	FILE	   *fp;
-	char		fnbuf[2048];
+	char		fnbuf[MAXPGPATH];
 	DH		   *dh = NULL;
 	int			codes;
 
-	if (pqGetpwuid(getuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd) == 0)
+	if (pqGetpwuid(getuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd) != 0)
 		return NULL;
 
 	/* attempt to open file.  It's not an error if it doesn't exist. */
-	snprintf(fnbuf, sizeof fnbuf, "%s/.postgresql/dh%d.pem",
+	snprintf(fnbuf, sizeof(fnbuf), "%s/.postgresql/dh%d.pem",
 			 pwd->pw_dir, keylength);
 
 	if ((fp = fopen(fnbuf, "r")) == NULL)
@@ -735,7 +737,7 @@ tmp_dh_cb(SSL *s, int is_export, int keylength)
  *	This callback is only called when the server wants a
  *	client cert.
  *
- *	Returns 1 on success, 0 on no data, -1 on error.
+ *	Must return 1 on success, 0 on no data or error.
  */
 static int
 client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
@@ -748,52 +750,52 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 	struct passwd *pwd = NULL;
 	struct stat buf,
 				buf2;
-	char		fnbuf[2048];
+	char		fnbuf[MAXPGPATH];
 	FILE	   *fp;
 	PGconn	   *conn = (PGconn *) SSL_get_app_data(ssl);
 	int			(*cb) () = NULL;	/* how to read user password */
 	char		sebuf[256];
 
 
-	if (pqGetpwuid(getuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd) == 0)
+	if (pqGetpwuid(getuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd) != 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
 					  libpq_gettext("could not get user information\n"));
-		return -1;
+		return 0;
 	}
 
 	/* read the user certificate */
-	snprintf(fnbuf, sizeof fnbuf, "%s/.postgresql/postgresql.crt",
+	snprintf(fnbuf, sizeof(fnbuf), "%s/.postgresql/postgresql.crt",
 			 pwd->pw_dir);
 	if (stat(fnbuf, &buf) == -1)
 		return 0;
 	if ((fp = fopen(fnbuf, "r")) == NULL)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-				  libpq_gettext("could not open certificate (%s): %s\n"),
+				  libpq_gettext("could not open certificate file \"%s\": %s\n"),
 						  fnbuf, pqStrerror(errno, sebuf, sizeof(sebuf)));
-		return -1;
+		return 0;
 	}
 	if (PEM_read_X509(fp, x509, NULL, NULL) == NULL)
 	{
 		char	   *err = SSLerrmessage();
 
 		printfPQExpBuffer(&conn->errorMessage,
-				  libpq_gettext("could not read certificate (%s): %s\n"),
+				  libpq_gettext("could not read certificate file \"%s\": %s\n"),
 						  fnbuf, err);
 		SSLerrfree(err);
 		fclose(fp);
-		return -1;
+		return 0;
 	}
 	fclose(fp);
 
 	/* read the user key */
-	snprintf(fnbuf, sizeof fnbuf, "%s/.postgresql/postgresql.key",
+	snprintf(fnbuf, sizeof(fnbuf), "%s/.postgresql/postgresql.key",
 			 pwd->pw_dir);
 	if (stat(fnbuf, &buf) == -1)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-		libpq_gettext("certificate present, but not private key (%s)\n"),
+		libpq_gettext("certificate present, but not private key file \"%s\"\n"),
 						  fnbuf);
 		X509_free(*x509);
 		return 0;
@@ -802,37 +804,38 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 		buf.st_uid != getuid())
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-		libpq_gettext("private key (%s) has wrong permissions\n"), fnbuf);
+		libpq_gettext("private key file \"%s\" has wrong permissions\n"),
+						  fnbuf);
 		X509_free(*x509);
-		return -1;
+		return 0;
 	}
 	if ((fp = fopen(fnbuf, "r")) == NULL)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			 libpq_gettext("could not open private key file (%s): %s\n"),
+			 libpq_gettext("could not open private key file \"%s\": %s\n"),
 						  fnbuf, pqStrerror(errno, sebuf, sizeof(sebuf)));
 		X509_free(*x509);
-		return -1;
+		return 0;
 	}
 	if (fstat(fileno(fp), &buf2) == -1 ||
 		buf.st_dev != buf2.st_dev || buf.st_ino != buf2.st_ino)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-						  libpq_gettext("private key (%s) changed during execution\n"), fnbuf);
+						  libpq_gettext("private key file \"%s\" changed during execution\n"), fnbuf);
 		X509_free(*x509);
-		return -1;
+		return 0;
 	}
 	if (PEM_read_PrivateKey(fp, pkey, cb, NULL) == NULL)
 	{
 		char	   *err = SSLerrmessage();
 
 		printfPQExpBuffer(&conn->errorMessage,
-				  libpq_gettext("could not read private key (%s): %s\n"),
+				  libpq_gettext("could not read private key file \"%s\": %s\n"),
 						  fnbuf, err);
 		SSLerrfree(err);
 		X509_free(*x509);
 		fclose(fp);
-		return -1;
+		return 0;
 	}
 	fclose(fp);
 
@@ -842,12 +845,12 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 		char	   *err = SSLerrmessage();
 
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("certificate/private key mismatch (%s): %s\n"),
+			libpq_gettext("certificate does not match private key file \"%s\": %s\n"),
 						  fnbuf, err);
 		SSLerrfree(err);
 		X509_free(*x509);
 		EVP_PKEY_free(*pkey);
-		return -1;
+		return 0;
 	}
 
 	return 1;
@@ -952,46 +955,35 @@ initialize_SSL(PGconn *conn)
 	char		pwdbuf[BUFSIZ];
 	struct passwd pwdstr;
 	struct passwd *pwd = NULL;
-	char		fnbuf[2048];
+	char		fnbuf[MAXPGPATH];
 #endif
 
 	if (init_ssl_system(conn))
 		return -1;
 
 #ifndef WIN32
+	/* Set up to verify server cert, if root.crt is present */
 	if (pqGetpwuid(getuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd) == 0)
 	{
-		snprintf(fnbuf, sizeof fnbuf, "%s/.postgresql/root.crt",
+		snprintf(fnbuf, sizeof(fnbuf), "%s/.postgresql/root.crt",
 				 pwd->pw_dir);
-		if (stat(fnbuf, &buf) == -1)
+		if (stat(fnbuf, &buf) == 0)
 		{
-			return 0;
-#ifdef NOT_USED
-			char		sebuf[256];
+			if (!SSL_CTX_load_verify_locations(SSL_context, fnbuf, NULL))
+			{
+				char	   *err = SSLerrmessage();
 
-			/* CLIENT CERTIFICATES NOT REQUIRED  bjm 2002-09-26 */
-			printfPQExpBuffer(&conn->errorMessage,
-							  libpq_gettext("could not read root certificate list (%s): %s\n"),
-						 fnbuf, pqStrerror(errno, sebuf, sizeof(sebuf)));
-			return -1;
-#endif
-		}
-		if (!SSL_CTX_load_verify_locations(SSL_context, fnbuf, 0))
-		{
-			char	   *err = SSLerrmessage();
+				printfPQExpBuffer(&conn->errorMessage,
+								  libpq_gettext("could not read root certificate file \"%s\": %s\n"),
+								  fnbuf, err);
+				SSLerrfree(err);
+				return -1;
+			}
 
-			printfPQExpBuffer(&conn->errorMessage,
-							  libpq_gettext("could not read root certificate list (%s): %s\n"),
-							  fnbuf, err);
-			SSLerrfree(err);
-			return -1;
+			SSL_CTX_set_verify(SSL_context, SSL_VERIFY_PEER, verify_cb);
 		}
 	}
 
-	SSL_CTX_set_verify(SSL_context,
-		   SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, verify_cb);
-	SSL_CTX_set_verify_depth(SSL_context, 1);
-
 	/* set up empheral DH keys */
 	SSL_CTX_set_tmp_dh_callback(SSL_context, tmp_dh_cb);
 	SSL_CTX_set_options(SSL_context, SSL_OP_SINGLE_DH_USE);