sulogin(8)

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sulogin(8)
NAME
  sulogin - single-user login program (Enhanced Security)

SYNOPSIS
  /sbin/sulogin

DESCRIPTION
  The sulogin program is run by the init process on the console terminal when
  entering single-user mode.  The sulogin program checks the system
  configuration to determine whether entering single-user mode requires
  entering the root password.  If it does not, then sulogin execs /sbin/sh
  with its argv[0] set to "-".	That same exec is also done if the root
  password is correctly entered.

  The decision to enter the single-user mode depends on the state of the
  system configuration files.  If the files cannot be read, then defaults are
  assumed (as described below).	 Therefore, the loss of a configuration file
  does not prevent access to the system console for repairing the problem.

  The sulogin program first checks the /etc/rc.config file for a the
  SECURE_CONSOLE variable.  If such a variable is present, and it is set to a
  true value (either "TRUE", "ON", "YES", or "1"), then the program asks for
  the root password.  The value of the SECURE_CONSOLE variable is checked in
  a case-independent fashion, and only a minimal match is necessary.  Thus,
  the value is really checked against the following regular expression:

	^([Tt]|1|[Yy]|[Oo][Nn]).*

  If the SECURE_CONSOLE variable is present, but does not have one of the
  true values, then sulogin does not ask for the root password, but simply
  execs /sbin/sh as previously described.

  If the SECURE_CONSOLE variable is not found in the /etc/rc.config file, or
  if that file is missing or unreadable, then an attempt is made to obtain
  the value of the console firmware setting of the SECURE variable, using the
  GSI_PROM_ENV function of the getsysinfo() system call.  If the check
  determines the console commands are password- protected, the sulogin
  program requests the root password.

  If sulogin has made the decision to request the root password, it also
  determines whether BASE or ENHANCED security should be used to validate
  that password.  This is done using the value of the SECURITY variable from
  the /etc/rc.config file, unless that file was not readable, in which case
  the /etc/sia/matrix.conf file is read, looking for a line beginning with
  the string "siad_ses_init=", and containing either "(OSFC2," or "(BSD,".
  If the /etc/rc.config file was readable, but the SECURITY variable was not
  set, then BASE security is assumed.  (This is how the /sbin/init.d/security
  script initializes the /etc/sia/matrix.conf file, as well).  If the
  /etc/rc.config file can not be read and the /etc/sia/matrix.conf file
  either can not be read or does not have an appropriate siad_ses_init line,
  then the sulogin program checks to see whether the /etc/passwd file
  contains a valid entry for root and whether the getespwnam("root") function
  returns a valid extended profile.  If both profile entries exist, but only
  one has a valid encrypted password field, that profile (and thus that
  security policy) is used.  If both passwords are valid, the BASE security
  policy is used.

  Once the sulogin program has determined which security policy to use, it
  checks whether that policy has a valid account entry for user root (if not
  already checked while determining which policy to use), and whether that
  entry has a password that can be matched.  If the password is impossible to
  match, or if no valid root profile exists, then sulogin prints a warning
  and execs /sbin/sh as previously described.  For BASE security, a null
  encrypted password field for root causes the program to exec /sbin/sh
  without complaining.

  If there is a matchable root password, sulogin prints out "Single-user root
  login" and prompts for the password.	If the entered password does not
  match (after the appropriate encryption if non-null), the program waits for
  5 seconds (to deter break-in attempts, displays "Sorry", and re-prompts.
  If the program is interrupted or receives and end-of-file condition while
  attempting to read a password from the console terminal, it simply exits.
  This normally causes init to enter multi-user mode (It depends on system
  configuration information in /etc/inittab, specifically the entry marked
  with "initdefault", which ships at run-level "3").  This may also cause
  init to prompt for a run level, or to restart the sulogin program.

  Finally, if a password was collected, and it did match, the exec of
  /sbin/sh is done.  If that exec fails, the reason for the failure is
  displayed, and the program sleeps for 5 seconds before exiting.  Upon
  exiting control of the console is returned to the init process, as
  previously described for interrupt or end-of-file.

FILES
  /etc/rc.config
  /etc/sia/matrix.conf
  /etc/passwd
  /tcb/files/auth.db (/tcb/files/auth/r/root)

RELATED INFORMATION
  login(1), getpwnam(3), getespwnam(3), dispcrypt(3), matrix.conf(4), init(8)

  Security
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