chromeos-base/chromeos-auth-config/files/chromeos-auth

# If we're not in dev-mode, skip to the system password stack.
auth [success=ignore default=4] pam_exec.so \
  quiet seteuid \
  /usr/bin/crossystem cros_debug?1

# Check if a custom devmode password file exists and prefer it.
auth [success=ignore default=1] pam_exec.so \
  quiet seteuid \
  /usr/bin/test -f /mnt/stateful_partition/etc/devmode.passwd

# If we get to pwdfile, use it or bypass the password-less login.
auth [success=done default=2] pam_pwdfile.so \
  pwdfile /mnt/stateful_partition/etc/devmode.passwd

# See if the account exists in /etc and does not yet have a system password
# set. Only then will we allow password-less login access (see below).
# For accounts not listed in /etc, or that have a password, we do not want
# to allow them to log in.
auth [success=ignore default=1] pam_exec.so \
  quiet seteuid \
  /usr/bin/awk -F: [ \
    BEGIN { ret = 1 } \
    $1 == ENVIRON["PAM_USER"\] && $2 == "*" { ret = 0 } \
    END { exit ret }] /etc/shadow

# If we get here, allow password-less access
auth sufficient pam_exec.so \
  quiet seteuid \
  /usr/bin/crossystem cros_debug?1

# Fallback to a system password if one was stamped in after initial build.