From fd85d07d4eebd6f702b19975f24cb8ac5a9b7d86 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Thu, 20 Nov 2008 20:45:30 +0000
Subject: [PATCH] Issue a proper error message when MD5 is attempted when
 db_user_namespace is enabled.

Also document this limitation.
---
 doc/src/sgml/client-auth.sgml |  2 ++
 doc/src/sgml/config.sgml      | 11 +++++++++++
 src/backend/libpq/auth.c      |  4 ++++
 src/backend/libpq/hba.c       |  9 +++++++++
 4 files changed, 26 insertions(+)

diff --git a/doc/src/sgml/client-auth.sgml b/doc/src/sgml/client-auth.sgml
index ca33b8861c..3cfd77faf0 100644
--- a/doc/src/sgml/client-auth.sgml
+++ b/doc/src/sgml/client-auth.sgml
@@ -712,6 +712,8 @@ omicron       bryanh            guest1
     If you are at all concerned about password
     <quote>sniffing</> attacks then <literal>md5</> is preferred.
     Plain <literal>password</> should always be avoided if possible.
+    <literal>md5</> cannot be used with <xref
+    linkend="guc-db-user-namespace">.
    </para>
 
    <para>
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 98d01065f7..b0de16ec2c 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -706,6 +706,17 @@ SET ENABLE_SEQSCAN TO OFF;
         before the user name is looked up by the server.
        </para>
 
+       <para>
+        <varname>db_user_namespace</> causes the client's and
+        server's user name representation to differ.
+        Authentication checks are always done with the server's user name
+        so authentication methods must be configured for the
+        server's user name, not the client's.  Because
+        <literal>md5</> uses the user name as salt on both the
+        client and server, <literal>md5</> cannot be used with
+        <varname>db_user_namespace</>.
+       </para>
+
        <note>
         <para>
          This feature is intended as a temporary measure until a
diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index 104cddb4f9..4fb728d963 100644
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -413,6 +413,10 @@ ClientAuthentication(Port *port)
 			break;
 
 		case uaMD5:
+			if (Db_user_namespace)
+				ereport(FATAL,
+						(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+						 errmsg("MD5 authentication is not supported when \"db_user_namespace\" is enabled")));
 			sendAuthRequest(port, AUTH_REQ_MD5);
 			status = recv_and_check_password_packet(port);
 			break;
diff --git a/src/backend/libpq/hba.c b/src/backend/libpq/hba.c
index 2b8ca9b1f4..78e36cd454 100644
--- a/src/backend/libpq/hba.c
+++ b/src/backend/libpq/hba.c
@@ -846,7 +846,16 @@ parse_hba_line(List *line, int line_num, HbaLine *parsedline)
 	else if (strcmp(token, "reject") == 0)
 		parsedline->auth_method = uaReject;
 	else if (strcmp(token, "md5") == 0)
+	{
+		if (Db_user_namespace)
+		{
+			ereport(LOG,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("MD5 authentication is not supported when \"db_user_namespace\" is enabled")));
+			return false;
+		}
 		parsedline->auth_method = uaMD5;
+	}
 	else if (strcmp(token, "pam") == 0)
 #ifdef USE_PAM
 		parsedline->auth_method = uaPAM;
-- 
2.39.5