Make superuser imply replication privilege. The idea of a privilege that

superuser doesn't have doesn't make much sense, as a superuser can do
whatever he wants through other means, anyway. So instead of granting
replication privilege to superusers in CREATE USER time by default, allow
replication connection from superusers whether or not they have the
replication privilege.

Patch by Noah Misch, per discussion on bug report #6264

Author: hlinnaka

doc/src/sgml/high-availability.sgml

@@ -797,23 +797,14 @@ archive_cleanup_command = 'pg_archivecleanup /path/to/archive %r'
      It is very important that the access privileges for replication be set up
      so that only trusted users can read the WAL stream, because it is
      easy to extract privileged information from it.  Standby servers must
-     authenticate to the primary as an account that has the
-     <literal>REPLICATION</> privilege. So a role with the
-     <literal>REPLICATION</> and <literal>LOGIN</> privileges needs to be
-     created on the primary.
+     authenticate to the primary as a superuser or an account that has the
+     <literal>REPLICATION</> privilege. It is recommended to create a
+     dedicated user account with <literal>REPLICATION</> and <literal>LOGIN</>
+     privileges for replication. While <literal>REPLICATION</> privilege gives
+     very high permissions, it does not allow the user to modify any data on
+     the primary system, which the <literal>SUPERUSER</> privilege does.
     </para>
 
-    <note>
-     <para>
-      It is recommended that a dedicated user account is used for replication.
-      While the <literal>REPLICATION</> privilege is granted to superuser
-      accounts by default, it is not recommended to use superuser accounts
-      for replication. While <literal>REPLICATION</> privilege gives very high
-      permissions, it does not allow the user to modify any data on the
-      primary system, which the <literal>SUPERUSER</> privilege does.
-     </para>
-    </note>
-
     <para>
      Client authentication for replication is controlled by a
      <filename>pg_hba.conf</> record specifying <literal>replication</> in the

doc/src/sgml/recovery-config.sgml

@@ -325,9 +325,8 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
           The connection string should specify the host name (or address)
           of the primary server, as well as the port number if it is not
           the same as the standby server's default.
-          Also specify a user name corresponding to a role that has the
-          <literal>REPLICATION</> and <literal>LOGIN</> privileges on the
-          primary (see
+          Also specify a user name corresponding to a suitably-privileged role
+          on the primary (see
           <xref linkend="streaming-replication-authentication">).
           A password needs to be provided too, if the primary demands password
           authentication.  It can be provided in the

doc/src/sgml/ref/create_role.sgml

@@ -185,8 +185,7 @@ CREATE ROLE <replaceable class="PARAMETER">name</replaceable> [ [ WITH ] <replac
         A role having the <literal>REPLICATION</> attribute is a very
         highly privileged role, and should only be used on roles actually
         used for replication. If not specified,
-        <literal>NOREPLICATION</literal> is the default for all roles except
-        superusers.
+        <literal>NOREPLICATION</literal> is the default.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/ref/pg_basebackup.sgml

@@ -50,12 +50,13 @@ PostgreSQL documentation
 
   <para>
    The backup is made over a regular <productname>PostgreSQL</productname>
-   connection, and uses the replication protocol. The connection must be
-   made with a user having <literal>REPLICATION</literal> permissions (see
-   <xref linkend="role-attributes">), and the user must be granted explicit
-   permissions in <filename>pg_hba.conf</filename>. The server must also
-   be configured with <xref linkend="guc-max-wal-senders"> set high enough
-   to leave at least one session available for the backup.
+   connection, and uses the replication protocol. The connection must be made
+   with a superuser or a user having <literal>REPLICATION</literal>
+   permissions (see <xref linkend="role-attributes">),
+   and <filename>pg_hba.conf</filename> must explicitly permit the replication
+   connection. The server must also be configured
+   with <xref linkend="guc-max-wal-senders"> set high enough to leave at least
+   one session available for the backup.
   </para>
 
   <para>

doc/src/sgml/ref/pg_receivexlog.sgml

@@ -50,13 +50,13 @@ PostgreSQL documentation
 
   <para>
    The transaction log is streamed over a regular
-   <productname>PostgreSQL</productname> connection, and uses the
-   replication protocol. The connection must be
-   made with a user having <literal>REPLICATION</literal> permissions (see
-   <xref linkend="role-attributes">), and the user must be granted explicit
-   permissions in <filename>pg_hba.conf</filename>. The server must also
-   be configured with <xref linkend="guc-max-wal-senders"> set high enough
-   to leave at least one session available for the stream.
+   <productname>PostgreSQL</productname> connection, and uses the replication
+   protocol. The connection must be made with a superuser or a user
+   having <literal>REPLICATION</literal> permissions (see
+   <xref linkend="role-attributes">), and <filename>pg_hba.conf</filename>
+   must explicitly permit the replication connection. The server must also be
+   configured with <xref linkend="guc-max-wal-senders"> set high enough to
+   leave at least one session available for the stream.
   </para>
  </refsect1>
 

doc/src/sgml/user-manag.sgml

@@ -169,16 +169,11 @@ CREATE USER <replaceable>name</replaceable>;
       <listitem>
        <para>
         A database superuser bypasses all permission checks, except the right
-        to log in or the right to initiate replication.  This is a
-        dangerous privilege and should not be used carelessly; it is best
-        to do most of your work as a role that is not a superuser.
-        To create a new database superuser, use <literal>CREATE ROLE
-        <replaceable>name</replaceable> SUPERUSER</literal>.  You must do
-        this as a role that is already a superuser. Creating a superuser
-        will by default also grant permissions to initiate streaming
-        replication. For increased security this can be disallowed using
-        <literal>CREATE ROLE <replaceable>name</replaceable> SUPERUSER
-        NOREPLICATION</literal>.
+        to log in.  This is a dangerous privilege and should not be used
+        carelessly; it is best to do most of your work as a role that is not a
+        superuser.  To create a new database superuser, use <literal>CREATE
+        ROLE <replaceable>name</replaceable> SUPERUSER</literal>.  You must do
+        this as a role that is already a superuser.
        </para>
       </listitem>
      </varlistentry>
@@ -217,7 +212,8 @@ CREATE USER <replaceable>name</replaceable>;
       <listitem>
        <para>
         A role must explicitly be given permission to initiate streaming
-        replication. A role used for streaming replication must always
+        replication (except for superusers, since those bypass all permission
+        checks). A role used for streaming replication must always
         have <literal>LOGIN</> permission as well. To create such a role, use
         <literal>CREATE ROLE <replaceable>name</replaceable> REPLICATION
         LOGIN</literal>.

src/backend/commands/user.c

@@ -239,16 +239,7 @@ CreateRole(CreateRoleStmt *stmt)
 	if (dpassword && dpassword->arg)
 		password = strVal(dpassword->arg);
 	if (dissuper)
-	{
 		issuper = intVal(dissuper->arg) != 0;
-
-		/*
-		 * Superusers get replication by default, but only if NOREPLICATION
-		 * wasn't explicitly mentioned
-		 */
-		if (issuper && !(disreplication && intVal(disreplication->arg) == 0))
-			isreplication = 1;
-	}
 	if (dinherit)
 		inherit = intVal(dinherit->arg) != 0;
 	if (dcreaterole)

src/backend/utils/init/postinit.c

@@ -659,11 +659,10 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 	{
 		Assert(!bootstrap);
 
-		/* must have authenticated as a replication role */
-		if (!is_authenticated_user_replication_role())
+		if (!superuser() && !is_authenticated_user_replication_role())
 			ereport(FATAL,
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-					 errmsg("must be replication role to start walsender")));
+					 errmsg("must be superuser or replication role to start walsender")));
 
 		/* process any options passed in the startup packet */
 		if (MyProcPort != NULL)