security-misc/usr/libexec/security-misc/pam-info

#!/bin/bash

## Copyright (C) 2019 - 2023 ENCRYPTED SUPPORT LP <adrelanos@whonix.org>
## See the file COPYING for copying conditions.

## To enable debug log, run:
## sudo touch /etc/pam-info-debug
##
## Debug log if enabled can be found in file:
## /root/pam-info-debug.txt

true "$0: START PHASE 1"

if test -f /etc/pam-info-debug || test -f /usr/local/etc/pam-info-debug ; then
   set -x
   exec 5>&1 1>> ~/pam-info-debug.txt
   exec 6>&2 2>> ~/pam-info-debug.txt
fi

true "$0: START PHASE 2"

set -o pipefail

## Debugging.
who_ami="$(whoami)"
true "$0: who_ami: $who_ami"
true "$0: PAM_USER: $PAM_USER"
true "$0: SUDO_USER: $SUDO_USER"

if [ "$PAM_USER" = "" ]; then
   true "$0: ERROR: Environment variable PAM_USER is unset!"
   exit 0
fi

grep_result="$(grep "accessfile=/etc/security/access-security-misc.conf" /etc/pam.d/common-account 2>/dev/null)"

## Check if grep matched something.
if [ ! "$grep_result" = "" ]; then
   ## Yes, grep matched.

   ## Check if not out commented.
   if ! echo "$grep_result" | grep -q "#" ; then
      ## Not out commented indeed.

      ## https://forums.whonix.org/t/etc-security-hardening-console-lockdown/8592

      if id --name --groups --zero "$PAM_USER" | grep --quiet --null-data --line-regexp --fixed-strings "console"; then
         console_allowed=true
      fi
      if id --name --groups --zero "$PAM_USER" | grep --quiet --null-data --line-regexp --fixed-strings "console-unrestricted"; then
         console_allowed=true
      fi

      if [ ! "$console_allowed" = "true" ]; then
         echo "\
$0: ERROR: PAM_USER: '$PAM_USER' is not a member of group 'console'
To unlock, run the following command as superuser:
(If you still have a sudo/root shell somewhere.)

adduser $PAM_USER console

However, possibly unlock procedure is required.
First boot into recovery mode at grub boot menu and then run above command.
See also:
https://www.kicksecure.com/wiki/root#console
" >&2
         exit 0
      fi
   fi
fi

## https://forums.whonix.org/t/how-strong-do-linux-user-account-passwords-have-to-be-when-using-full-disk-encryption-fde-too/7698

## Does not work (yet) for login, pam_securetty runs before and aborts.
## Also this should only run for login since securetty covers only login.
# if [ "$PAM_USER" = "root" ]; then
#    if [ -f /etc/securetty ]; then
#       grep_result="$(grep "^[^#]" /etc/securetty)"
#       if [ "$grep_result" = "" ]; then
#          echo "\
# $0: ERROR: Root login is disabled.
# ERROR: This is because /etc/securetty is empty.
# See also:
# https://www.kicksecure.com/wiki/root#login
# " >&2
#          exit 0
#       fi
#    fi
# fi

## as user "user"
## /usr/sbin/faillock -u user
## faillock: Error opening /var/log/tallylog for update: Permission denied
## /usr/sbin/faillock: Authentication error
##
## xscreensaver runs as user "user", therefore pam_faillock cannot function.
## xscreensaver has its own failed login counter.
##
## https://askubuntu.com/questions/983183/how-lock-the-unlock-screen-after-wrong-password-attempts
##
## https://www.whonix.org/pipermail/whonix-devel/2019-September/001439.html
##
## Checking exit code to avoid breaking when read-only disk boot but
## without ro-mode-init or grub-live being used.
if ! pam_faillock_output="$(faillock --user "$PAM_USER")" ; then
   true "$0: faillock non-zero exit code."
   exit 0
fi

if [ "$pam_faillock_output" = "" ]; then
   true "$0: no failed login"
   exit 0
fi

## example pam_faillock_output (stdout):
## user:
## When                Type  Source                                           Valid
## 2021-08-10 16:26:33 RHOST                                                      V
## 2021-08-10 16:26:54 RHOST                                                      V

## example pam_faillock_output (stderr):
## faillock: No user name supplied.
## Usage: faillock [--dir /path/to/tally-directory] [--user username] [--reset]

## Get first line.
#pam_faillock_output_first_line="$(echo "$pam_faillock_output" | head --lines=1)"
while read -t 10 -r pam_faillock_output_first_line ; do
   break
done <<< "$pam_faillock_output"

true "pam_faillock_output_first_line: '$pam_faillock_output_first_line'"
## example pam_faillock_output_first_line:
## user:

user_name="$(echo "$pam_faillock_output_first_line" | LANG=C str_replace ":" "")"
## example user_name:
## user
## root

pam_faillock_output_count="$(echo "$pam_faillock_output" | wc -l)"
## example pam_faillock_output_count:
## 2
## example pam_faillock_output_count:
## 4

## Do not count the first two informational textual output lines
## (starting with "user:" and "When").
failed_login_counter=$(( pam_faillock_output_count - 2 ))

## example failed_login_counter:
## 2

if [ "$failed_login_counter" = "0" ]; then
   true "$0: INFO: Failed login counter is 0, ok."
   exit 0
fi

## pam_faillock default if it cannot be determined below.
deny=3

if test -f /etc/security/faillock.conf ; then
   deny_line=$(grep --invert-match "#" /etc/security/faillock.conf | grep "deny =")
   deny="$(echo "$deny_line" | LANG=C str_replace "=" "" | LANG=C str_replace "deny" "" | LANG=C str_replace " " "")"
   ## Example:
   #deny=50
fi

if [[ "$deny" == *[!0-9]* ]]; then
   echo "\
$0: ERROR: deny is not numeric. deny: '$deny'
ERROR: Please report this bug.
" >&2
   exit 0
fi

remaining_attempts="$(( $deny - $failed_login_counter ))"

if [ "$remaining_attempts" -le "0" ]; then
   echo "\
$0: ERROR: Login blocked after $failed_login_counter attempts.
To unlock, run the following command as superuser:
(If you still have a sudo/root shell somewhere.)

faillock --reset --user $PAM_USER

However, most likely unlock procedure is required.
First boot into recovery mode at grub boot menu and then run above command.
See also:
https://www.kicksecure.com/wiki/root#unlock
" >&2
   exit 0
fi

echo "\
$0: WARNING: $failed_login_counter failed login attempts for user_name '$user_name'.
Login will be blocked after $deny attempts.
You have $remaining_attempts more attempts before unlock procedure is required.
" >&2

if [ "$PAM_SERVICE" = "su" ]; then
   echo "\
$0: NOTE: Type the password. When entering the password, no password feedback (no asterisk (\"*\") symbol) will be shown.
" >&2
fi

true "$0: END"

exit 0