$ORACLE_HOME/rdbms/lib/config.c

As per a comment in $ORACLE_HOME/rdbms/lib/config.c defines the structure ss_dba_grp which defines the group id for SQL/dba administrative access (by default: dba, oper, bakupdba, dgdba, kmdba and racdba).

This structure seems to be related to the entries found in the password file ($ORACLE_HOME/dbs/orapw$ORACLE_SID).

As per a comment found in this source file, it needs to be in sync with rdbms/src/server/osds/config.c, specifically regarding the number of elemetns in the ss_dba_grp array.

If confic.c is modified, it can be compiled with

$ make -f ins_rdbms.mk config.o
$ make -f ins_rdbms.mk ioracle