iopsys-feed/sshmngr/files/openssh_backend/lib/sshmngr/pam_config.sh
2025-12-09 16:34:10 +05:30

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#!/bin/sh
# List of required .so files
REQUIRED_MODULES="
/usr/lib/security/pam_faildelay.so
/usr/lib/security/pam_faillock.so
/usr/lib/security/pam_unix.so
/usr/lib/security/pam_deny.so
/usr/lib/security/pam_permit.so
/usr/lib/security/pam_passwdqc.so
"
MFA_APP="google-authenticator"
MFA_LIB="/usr/lib/security/pam_google_authenticator.so"
MFA_DIR="/etc/security"
MFA_SECRET_FILE="${MFA_DIR}/mfa_secret"
MFA_QR_FILE="${MFA_DIR}/mfa_qr"
log() {
echo "$*" | logger -t sshd.init -p info
}
log_err() {
echo "$*" | logger -t sshd.init -p err
}
check_required_modules() {
for mod in $REQUIRED_MODULES; do
if [ ! -f "$mod" ]; then
log_err "ERROR: Cannot setup security policy, missing PAM module: $mod"
return 1
fi
done
return 0
}
write_line() {
local filepath="$1"
local line="$2"
echo "$line" >> "$filepath"
}
compare_and_replace() {
local src dst
src="$1"
dst="$2"
if [ ! -f "$dst" ] || ! cmp -s "$src" "$dst"; then
cp "$src" "$dst"
log "Updated $dst"
fi
}
setup_mfa() {
mkdir -p "$MFA_DIR"
if [ -f "${MFA_SECRET_FILE}" ] && [ -f "${MFA_QR_FILE}" ]; then
log "Not updating MFA files, they already exist"
return
fi
touch "$MFA_SECRET_FILE"
touch "$MFA_QR_FILE"
chmod 600 "$MFA_SECRET_FILE"
chmod 600 "$MFA_QR_FILE"
local cmd="$MFA_APP -f -s $MFA_SECRET_FILE -C -t -d -r 3 -R 30 -w 3 -Q UTF8 -e 3"
log "Running MFA app: $cmd"
# if the google-authenticator senses that the output is not going to a terminal
# then it does not print out the QR, so simple redirection does not work
# we have to run the command inside a pseudo-terminal using script command
# and then redirect that output to a file
cmd="script -q -c \"$cmd\" $MFA_QR_FILE > /dev/null"
eval "$cmd"
}
update_auth() {
# Write /etc/pam.d/sshd-auth
local tmp_file pam_file
tmp_file="/tmp/sshd-auth"
pam_file="/etc/pam.d/sshd-auth"
local auth_enabled="${1}"
local enabled="${2}"
local mfa_enabled="${3}"
local faildelay="$(uci -q get users.authentication_policy.fail_delay || echo 3)"
local faillock_lockout_time="$(uci -q get users.authentication_policy.faillock_lockout_time || echo 300)"
local faillock_attempts="$(uci -q get users.authentication_policy.faillock_attempts || echo 6)"
# Convert seconds to microseconds for pam_faildelay
local faildelay_usec=$((faildelay * 1000000))
rm -f "$tmp_file"
touch "$tmp_file"
if [ "${auth_enabled}" -eq 1 ] && [ "${enabled}" -eq 1 ]; then
write_line "$tmp_file" "auth optional pam_faildelay.so delay=$faildelay_usec"
write_line "$tmp_file" "auth required pam_faillock.so preauth deny=$faillock_attempts even_deny_root unlock_time=$faillock_lockout_time"
fi
write_line "$tmp_file" "auth [success=1 default=bad] pam_unix.so nullok_secure"
write_line "$tmp_file" "auth [default=die] pam_faillock.so authfail audit deny=$faillock_attempts even_deny_root unlock_time=$faillock_lockout_time"
if [ "$mfa_enabled" -eq 1 ]; then
write_line "$tmp_file" "auth [success=1 default=bad] pam_google_authenticator.so secret=$MFA_SECRET_FILE"
write_line "$tmp_file" "auth [default=die] pam_faillock.so authfail audit deny=$faillock_attempts even_deny_root unlock_time=$faillock_lockout_time"
fi
write_line "$tmp_file" "auth sufficient pam_faillock.so authsucc audit deny=$faillock_attempts even_deny_root unlock_time=$faillock_lockout_time"
write_line "$tmp_file" "auth requisite pam_deny.so"
compare_and_replace "$tmp_file" "$pam_file"
}
build_pam_passwdqc_line() {
local base="password requisite pam_passwdqc.so"
local k v line
for line in $(uci show users.passwdqc 2>/dev/null); do
case "$line" in
users.passwdqc=*) continue ;;
users.passwdqc.enabled=*) continue ;;
esac
k="${line%%=*}"
k="${k#users.passwdqc.}"
v="${line#*=}"
v="${v%\'}"
v="${v#\'}"
base="$base $k=$v"
done
base="$base match=0"
echo "$base"
}
# NOTE:
# for some reason setting min 8 makes passwdqc accept minimum 12 letter password with this configuration
# if we set it to 12 then we need atleast 16 characters and so on
# passphrase = 0 means no space separated words
# passphrase = N means the number of words required for a passphrase or 0 to disable the support for user-chosen passphrases.
# rest can be figured out from passwdqc man page
update_password() {
local tmp_file pam_file enabled line
tmp_file="/tmp/sshd-password"
pam_file="/etc/pam.d/sshd-password"
local auth_enabled="${1}"
rm -f "$tmp_file"
touch "$tmp_file"
# Check if section exists
if uci -q get users.passwdqc >/dev/null 2>&1; then
# if enabled is not present it is assumed to be 0
enabled=$(uci -q get users.passwdqc.enabled || echo "0")
if [ "${auth_enabled}" -eq 1 ] && [ "${enabled}" -eq 1 ]; then
line="$(build_pam_passwdqc_line)"
write_line "$tmp_file" "$line"
fi
fi
write_line "$tmp_file" "password [success=1 default=ignore] pam_unix.so sha512"
write_line "$tmp_file" ""
write_line "$tmp_file" "password requisite pam_deny.so"
write_line "$tmp_file" "password required pam_permit.so"
compare_and_replace "$tmp_file" "$pam_file"
}
update_account() {
# Write /etc/pam.d/sshd-account
local tmp_file pam_file
tmp_file="/tmp/sshd-account"
pam_file="/etc/pam.d/sshd-account"
local auth_enabled="${1}"
local enabled="${2}"
rm -f "$tmp_file"
touch "$tmp_file"
if [ "${auth_enabled}" -eq 1 ] && [ "${enabled}" -eq 1 ]; then
write_line "$tmp_file" "account required pam_faillock.so"
fi
write_line "$tmp_file" "account [success=1 new_authtok_reqd=done default=ignore] pam_unix.so"
write_line "$tmp_file" ""
write_line "$tmp_file" "account requisite pam_deny.so"
write_line "$tmp_file" "account required pam_permit.so"
compare_and_replace "$tmp_file" "$pam_file"
}
handle_security_policy() {
local auth_enabled enabled
local use_mfa mfa_enabled
# Read UCI values
auth_enabled="$(uci -q get users.users.auth_policy_enable || echo 0)"
enabled="$(uci -q get users.authentication_policy.enabled || echo 0)"
use_mfa="$(uci -q get sshd.@sshd[0].UseMFA || echo 0)"
# if any .so files are missing, then we cannot setup security
if ! check_required_modules; then
return
fi
# Detect and enable MFA only if requested and module exists
if which "$MFA_APP" > /dev/null 2>&1 && [ "$use_mfa" = "1" ] && [ -f "$MFA_LIB" ]; then
mfa_enabled=1
setup_mfa
else
rm -rf "${MFA_QR_FILE}"
rm -rf "${MFA_SECRET_FILE}"
mfa_enabled=0
fi
update_auth "${auth_enabled}" "${enabled}" "${mfa_enabled}"
update_account "${auth_enabled}" "${enabled}"
update_password "${auth_enabled}"
}