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

#!/bin/bash

## Copyright (C) 2019 - 2022 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)"

if [ ! "$(id -u)" = "0" ]; then
   ## 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
   ## TODO: echo -> true
   echo "$0: not started as root, exiting."
   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'" >&2
         echo "$0: To unlock, run the following command as superuser:" >&2
         echo "$0: (If you still have a sudo/root shell somewhere.)" >&2
         echo "" >&2
         echo "adduser $PAM_USER console" >&2
         echo "" >&2
         echo "$0: However, possibly unlock procedure is required." >&2
         echo "$0: First boot into recovery mode at grub boot menu and then run above command." >&2
         echo "$0: See also:" >&2
         echo "https://www.kicksecure.com/wiki/root#console" >&2
         echo "" >&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." >&2
#          echo "$0: ERROR: This is because /etc/securetty is empty." >&2
#          echo "$0: See also:" >&2
#          echo "https://www.kicksecure.com/wiki/root#login" >&2
#          echo "" >&2
#          exit 0
#       fi
#    fi
# fi

## 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" 2>&1)" ; 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

if [ ! "$PAM_USER" = "$user_name" ]; then
   echo "$0: ERROR: PAM_USER: '$PAM_USER' does not equal user_name: '$user_name'." >&2
   echo "$0: ERROR: Please report this bug." >&2
   echo "" >&2
   exit 0
fi

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'" >&2
   echo "$0: ERROR: Please report this bug." >&2
   echo "" >&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." >&2
   echo "$0: To unlock, run the following command as superuser:" >&2
   echo "$0: (If you still have a sudo/root shell somewhere.)" >&2
   echo "" >&2
   echo "faillock --reset --user $PAM_USER" >&2
   echo "" >&2
   echo "$0: However, most likely unlock procedure is required." >&2
   echo "$0: First boot into recovery mode at grub boot menu and then run above command." >&2
   echo "$0: See also:" >&2
   echo "https://www.kicksecure.com/wiki/root#unlock" >&2
   echo "" >&2
   exit 0
fi

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

true "$0: END"

exit 0