Obstruct shell, SQL, and conninfo injection via database and role names.

Due to simplistic quoting and confusion of database names with conninfo
strings, roles with the CREATEDB or CREATEROLE option could escalate to
superuser privileges when a superuser next ran certain maintenance
commands.  The new coding rule for PQconnectdbParams() calls, documented
at conninfo_array_parse(), is to pass expand_dbname=true and wrap
literal database names in a trivial connection string.  Escape
zero-length values in appendConnStrVal().  Back-patch to 9.1 (all
supported versions).

Nathan Bossart, Michael Paquier, and Noah Misch.  Reviewed by Peter
Eisentraut.  Reported by Nathan Bossart.

Security: CVE-2016-5424

1 files changed, 8 insertions, 1 deletions

diff --git a/src/bin/scripts/clusterdb.c b/src/bin/scripts/clusterdb.c
index 4481d3f2e64..1bdfe2967c2 100644
--- a/src/bin/scripts/clusterdb.c
+++ b/src/bin/scripts/clusterdb.c
@@ -229,6 +229,7 @@ cluster_all_databases(bool verbose, const char *maintenance_db,
 {
 	PGconn	   *conn;
 	PGresult   *result;
+	PQExpBufferData connstr;
 	int			i;
 
 	conn = connectMaintenanceDatabase(maintenance_db, host, port, username,
@@ -236,6 +237,7 @@ cluster_all_databases(bool verbose, const char *maintenance_db,
 	result = executeQuery(conn, "SELECT datname FROM pg_database WHERE datallowconn ORDER BY 1;", progname, echo);
 	PQfinish(conn);
 
+	initPQExpBuffer(&connstr);
 	for (i = 0; i < PQntuples(result); i++)
 	{
 		char	   *dbname = PQgetvalue(result, i, 0);
@@ -246,10 +248,15 @@ cluster_all_databases(bool verbose, const char *maintenance_db,
 			fflush(stdout);
 		}
 
-		cluster_one_database(dbname, verbose, NULL,
+		resetPQExpBuffer(&connstr);
+		appendPQExpBuffer(&connstr, "dbname=");
+		appendConnStrVal(&connstr, dbname);
+
+		cluster_one_database(connstr.data, verbose, NULL,
 							 host, port, username, prompt_password,
 							 progname, echo);
 	}
+	termPQExpBuffer(&connstr);
 
 	PQclear(result);
 }