fix: shellcheck issues

This commit is contained in:
Krzysztof Rudnicki 2025-11-01 15:36:22 +01:00
parent dcd4251992
commit fef44f0015
6 changed files with 178 additions and 117 deletions

View File

@ -9,24 +9,24 @@ TARGET="/etc/hosts"
LOG_FILE="/var/log/hosts-guard.log"
log() {
printf '%s - %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" | tee -a "$LOG_FILE" >&2
printf '%s - %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" | tee -a "$LOG_FILE" >&2
}
if [[ ! -f "$CANONICAL_SOURCE" ]]; then
log "Canonical hosts not found at $CANONICAL_SOURCE; aborting enforcement"
exit 0
if [[ ! -f $CANONICAL_SOURCE ]]; then
log "Canonical hosts not found at $CANONICAL_SOURCE; aborting enforcement"
exit 0
fi
if ! cmp -s "$CANONICAL_SOURCE" "$TARGET"; then
log "Difference detected – restoring $TARGET from canonical copy"
cp "$CANONICAL_SOURCE" "$TARGET"
chmod 644 "$TARGET"
log "Difference detected – restoring $TARGET from canonical copy"
cp "$CANONICAL_SOURCE" "$TARGET"
chmod 644 "$TARGET"
else
log "No drift detected (contents identical)"
log "No drift detected (contents identical)"
fi
# Re-apply protective attributes: immutable first, then read-only bind mount handled by separate unit
chattr -i -a "$TARGET" 2>/dev/null || true
chattr -i -a "$TARGET" 2> /dev/null || true
chattr +i "$TARGET" || log "Failed to set immutable attribute"
log "Enforcement complete"
log "Enforcement complete"

View File

@ -1,7 +1,7 @@
#!/usr/bin/env bash
set -euo pipefail
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi }
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi; }
require_root "$@"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@ -10,7 +10,7 @@ HOOKS_DIR="/etc/pacman.d/hooks"
install -d -m 755 "$HOOKS_DIR"
# Pre-transaction hook
cat >"$HOOKS_DIR/10-unlock-etc-hosts.hook" <<'HOOK'
cat > "$HOOKS_DIR/10-unlock-etc-hosts.hook" << 'HOOK'
[Trigger]
Operation = Upgrade
Operation = Install
@ -26,7 +26,7 @@ NeedsTargets
HOOK
# Post-transaction hook
cat >"$HOOKS_DIR/90-relock-etc-hosts.hook" <<'HOOK'
cat > "$HOOKS_DIR/90-relock-etc-hosts.hook" << 'HOOK'
[Trigger]
Operation = Upgrade
Operation = Install

View File

@ -5,22 +5,22 @@ TARGET=/etc/hosts
ENFORCE=/usr/local/sbin/enforce-hosts.sh
LOGTAG=hosts-guard-hook
mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2>/dev/null || echo 0; }
mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2> /dev/null || echo 0; }
collapse_mounts() {
local i=0
if command -v mountpoint >/devnull 2>&1; then
if command -v mountpoint > /devnull 2>&1; then
while mountpoint -q "$TARGET"; do
umount -l "$TARGET" >/dev/null 2>&1 || break
i=$((i+1))
(( i > 20 )) && break
umount -l "$TARGET" > /dev/null 2>&1 || break
i=$((i + 1))
((i > 20)) && break
done
else
local cnt
cnt=$(mount_layers_count)
while (( cnt > 1 )); do
umount -l "$TARGET" >/dev/null 2>&1 || break
i=$((i+1))
(( i > 20 )) && break
while ((cnt > 1)); do
umount -l "$TARGET" > /dev/null 2>&1 || break
i=$((i + 1))
((i > 20)) && break
cnt=$(mount_layers_count)
done
fi
@ -28,23 +28,23 @@ collapse_mounts() {
# Ensure we end with a single read-only bind mount layer
logger -t "$LOGTAG" "post: relocking /etc/hosts (starting)"
echo "$(date -Is) post-relock(start)" >> /run/hosts-guard-hook.log 2>/dev/null || true
echo "$(date -Is) post-relock(start)" >> /run/hosts-guard-hook.log 2> /dev/null || true
collapse_mounts
if [[ -x "$ENFORCE" ]]; then
"$ENFORCE" >/dev/null 2>&1 || true
if [[ -x $ENFORCE ]]; then
"$ENFORCE" > /dev/null 2>&1 || true
fi
# Apply exactly one ro bind layer
mount --bind "$TARGET" "$TARGET" >/dev/null 2>&1 || true
mount -o remount,ro,bind "$TARGET" >/dev/null 2>&1 || true
mount --bind "$TARGET" "$TARGET" > /dev/null 2>&1 || true
mount -o remount,ro,bind "$TARGET" > /dev/null 2>&1 || true
# Start only the path watcher; avoid bind-mount service (we already bound once)
if command -v systemctl >/dev/null 2>&1; then
systemctl start hosts-guard.path >/dev/null 2>&1 || true
if command -v systemctl > /dev/null 2>&1; then
systemctl start hosts-guard.path > /dev/null 2>&1 || true
fi
logger -t "$LOGTAG" "post: relocking /etc/hosts (done)"
echo "$(date -Is) post-relock(done)" >> /run/hosts-guard-hook.log 2>/dev/null || true
echo "$(date -Is) post-relock(done)" >> /run/hosts-guard-hook.log 2> /dev/null || true
exit 0

View File

@ -7,58 +7,57 @@ LOGTAG=hosts-guard-hook
stop_units_if_present() {
local units=(hosts-bind-mount.service hosts-guard.path)
for u in "${units[@]}"; do
if command -v systemctl >/dev/null 2>&1; then
if systemctl list-unit-files 2>/dev/null | grep -q "^$u"; then
systemctl stop "$u" >/dev/null 2>&1 || true
if command -v systemctl > /dev/null 2>&1; then
if systemctl list-unit-files 2> /dev/null | grep -q "^$u"; then
systemctl stop "$u" > /dev/null 2>&1 || true
fi
fi
done
}
is_ro_mount() { findmnt -no OPTIONS -T "$TARGET" 2>/dev/null | grep -qw ro; }
is_bind_mount() { findmnt -no OPTIONS -T "$TARGET" 2>/dev/null | grep -qw bind; }
is_ro_mount() { findmnt -no OPTIONS -T "$TARGET" 2> /dev/null | grep -qw ro; }
mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2>/dev/null || echo 0; }
mount_layers_count() { awk '$5=="/etc/hosts"{c++} END{print c+0}' /proc/self/mountinfo 2> /dev/null || echo 0; }
cleanup_mount_stacks() {
local i=0
# Unmount bind layers until /etc/hosts is no longer a mountpoint
if command -v mountpoint >/dev/null 2>&1; then
if command -v mountpoint > /dev/null 2>&1; then
while mountpoint -q "$TARGET"; do
umount -l "$TARGET" >/dev/null 2>&1 || break
i=$((i+1))
(( i > 20 )) && break
umount -l "$TARGET" > /dev/null 2>&1 || break
i=$((i + 1))
((i > 20)) && break
done
else
# Fallback to best-effort using mountinfo count
local cnt
cnt=$(mount_layers_count)
while (( cnt > 1 )); do
umount -l "$TARGET" >/dev/null 2>&1 || break
i=$((i+1))
(( i > 20 )) && break
while ((cnt > 1)); do
umount -l "$TARGET" > /dev/null 2>&1 || break
i=$((i + 1))
((i > 20)) && break
cnt=$(mount_layers_count)
done
fi
}
# Drop protective attributes if present
if command -v lsattr >/dev/null 2>&1; then
attrs=$(lsattr -d "$TARGET" 2>/dev/null || true)
echo "$attrs" | grep -q " i " && chattr -i "$TARGET" >/dev/null 2>&1 || true
echo "$attrs" | grep -q " a " && chattr -a "$TARGET" >/dev/null 2>&1 || true
if command -v lsattr > /dev/null 2>&1; then
attrs=$(lsattr -d "$TARGET" 2> /dev/null || true)
echo "$attrs" | grep -q " i " && chattr -i "$TARGET" > /dev/null 2>&1 || true
echo "$attrs" | grep -q " a " && chattr -a "$TARGET" > /dev/null 2>&1 || true
fi
stop_units_if_present
logger -t "$LOGTAG" "pre: unlocking /etc/hosts (starting)"
echo "$(date -Is) pre-unlock" >> /run/hosts-guard-hook.log 2>/dev/null || true
echo "$(date -Is) pre-unlock" >> /run/hosts-guard-hook.log 2> /dev/null || true
# Always collapse any existing layers; we'll operate on the plain file
cleanup_mount_stacks
# If someone managed a ro single-layer mount, ensure rw by remounting or collapsing again
if is_ro_mount; then
mount -o remount,rw "$TARGET" >/dev/null 2>&1 || cleanup_mount_stacks
mount -o remount,rw "$TARGET" > /dev/null 2>&1 || cleanup_mount_stacks
fi
logger -t "$LOGTAG" "pre: unlocking /etc/hosts (done)"

View File

@ -11,36 +11,36 @@ DELAY_SECONDS=45
log() { printf '%s - %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" | tee -a "$LOG" >&2; }
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi }
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi; }
require_root "$@"
echo "Reason for editing /etc/hosts (will be logged):" >&2
read -r -p "Enter reason: " REASON
if [[ -z ${REASON// } ]]; then
echo "Empty reason not allowed. Aborting." >&2
exit 1
if [[ -z ${REASON// /} ]]; then
echo "Empty reason not allowed. Aborting." >&2
exit 1
fi
log "Requested intentional /etc/hosts modification session. Reason: $REASON"
logger -t "$SYSLOG_TAG" "session_start user=${SUDO_USER:-$USER} reason='$REASON'"
echo "This action is logged. A cooling-off delay of $DELAY_SECONDS seconds applies." >&2
for s in hosts-bind-mount.service hosts-guard.path; do
if systemctl is-active --quiet "$s"; then
log "Stopping $s"
systemctl stop "$s" || true
fi
if systemctl is-enabled --quiet "$s"; then
log "(Will re-enable later)"
fi
if systemctl is-active --quiet "$s"; then
log "Stopping $s"
systemctl stop "$s" || true
fi
if systemctl is-enabled --quiet "$s"; then
log "(Will re-enable later)"
fi
done
# Remove attributes to allow edit
chattr -i -a "$TARGET" 2>/dev/null || true
chattr -i -a "$TARGET" 2> /dev/null || true
echo "Countdown:" >&2
for ((i=DELAY_SECONDS; i>0; i--)); do
printf '\rEdit window opens in %2d seconds... Press Ctrl+C to abort.' "$i" >&2
sleep 1
for ((i = DELAY_SECONDS; i > 0; i--)); do
printf '\rEdit window opens in %2d seconds... Press Ctrl+C to abort.' "$i" >&2
sleep 1
done
echo >&2
@ -49,13 +49,13 @@ sha_before=$(sha256sum "$TARGET" | awk '{print $1}')
"$EDITOR_CMD" "$TARGET"
sha_after=$(sha256sum "$TARGET" | awk '{print $1}')
if [[ "$sha_before" == "$sha_after" ]]; then
log "No changes made to $TARGET. Reason: $REASON"
logger -t "$SYSLOG_TAG" "no_change user=${SUDO_USER:-$USER} reason='$REASON'"
if [[ $sha_before == "$sha_after" ]]; then
log "No changes made to $TARGET. Reason: $REASON"
logger -t "$SYSLOG_TAG" "no_change user=${SUDO_USER:-$USER} reason='$REASON'"
else
log "Changes detected. Updating canonical copy and re-enforcing. Reason: $REASON"
logger -t "$SYSLOG_TAG" "modified user=${SUDO_USER:-$USER} reason='$REASON'"
cp "$TARGET" "$CANON"
log "Changes detected. Updating canonical copy and re-enforcing. Reason: $REASON"
logger -t "$SYSLOG_TAG" "modified user=${SUDO_USER:-$USER} reason='$REASON'"
cp "$TARGET" "$CANON"
fi
# Re-run enforcement

View File

@ -46,10 +46,20 @@ ADD_ALIAS_STUB=1
msg() { printf '\e[1;32m[+]\e[0m %s\n' "$*"; }
note() { printf '\e[1;34m[i]\e[0m %s\n' "$*"; }
warn() { printf '\e[1;33m[!]\e[0m %s\n' "$*"; }
err() { printf '\e[1;31m[x]\e[0m %s\n' "$*" >&2; }
run() { if [[ $DRY_RUN -eq 1 ]]; then printf 'DRY-RUN: %s\n' "$*"; else eval "$@"; fi }
err() { printf '\e[1;31m[x]\e[0m %s\n' "$*" >&2; }
run() {
if [[ $DRY_RUN -eq 1 ]]; then
printf 'DRY-RUN:'
if [ "$#" -gt 0 ]; then
printf ' %q' "$@"
fi
printf '\n'
else
"$@"
fi
}
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi }
require_root() { if [[ $EUID -ne 0 ]]; then exec sudo -E bash "$0" "$@"; fi; }
usage() { sed -n '1,/^set -euo pipefail/p' "$0" | sed 's/^# \{0,1\}//'; }
@ -58,21 +68,71 @@ usage() { sed -n '1,/^set -euo pipefail/p' "$0" | sed 's/^# \{0,1\}//'; }
######################################################################
while [[ $# -gt 0 ]]; do
case "$1" in
--force-snapshot) FORCE_SNAPSHOT=1 ; shift ;;
--no-snapshot) DO_SNAPSHOT=0 ; shift ;;
--skip-bind) ENABLE_BIND=0 ; shift ;;
--skip-path-watch) ENABLE_PATH=0 ; shift ;;
--delay) DELAY=${2:-} ; [[ -z ${DELAY} ]] && { err '--delay requires value'; exit 2; } ; shift 2 ;;
--dry-run) DRY_RUN=1 ; shift ;;
--no-shell-hooks) INSTALL_SHELL_HOOKS=0 ; shift ;;
--shell-hooks) INSTALL_SHELL_HOOKS=1 ; shift ;;
--no-audit) INSTALL_AUDIT_RULE=0 ; shift ;;
--audit) INSTALL_AUDIT_RULE=1 ; shift ;;
--no-alias-stub) ADD_ALIAS_STUB=0 ; shift ;;
--alias-stub) ADD_ALIAS_STUB=1 ; shift ;;
--uninstall) UNINSTALL=1 ; shift ;;
-h|--help) usage; exit 0 ;;
*) err "Unknown argument: $1"; usage; exit 2 ;;
--force-snapshot)
FORCE_SNAPSHOT=1
shift
;;
--no-snapshot)
DO_SNAPSHOT=0
shift
;;
--skip-bind)
ENABLE_BIND=0
shift
;;
--skip-path-watch)
ENABLE_PATH=0
shift
;;
--delay)
DELAY=${2:-}
[[ -z ${DELAY} ]] && {
err '--delay requires value'
exit 2
}
shift 2
;;
--dry-run)
DRY_RUN=1
shift
;;
--no-shell-hooks)
INSTALL_SHELL_HOOKS=0
shift
;;
--shell-hooks)
INSTALL_SHELL_HOOKS=1
shift
;;
--no-audit)
INSTALL_AUDIT_RULE=0
shift
;;
--audit)
INSTALL_AUDIT_RULE=1
shift
;;
--no-alias-stub)
ADD_ALIAS_STUB=0
shift
;;
--alias-stub)
ADD_ALIAS_STUB=1
shift
;;
--uninstall)
UNINSTALL=1
shift
;;
-h | --help)
usage
exit 0
;;
*)
err "Unknown argument: $1"
usage
exit 2
;;
esac
done
@ -119,7 +179,7 @@ if [[ $UNINSTALL -eq 1 ]]; then
"$SYSTEMD_DIR/hosts-bind-mount.service" \
"$ZSH_FILTER_SNIPPET" \
"$BASH_FILTER_SNIPPET"; do
if [[ -e $f ]]; then run rm -f "$f"; fi
if [[ -e $f ]]; then run rm -f "$f"; fi
done
note "Leaving canonical snapshot at $CANON (remove manually if undesired)."
if [[ $DRY_RUN -eq 0 ]]; then systemctl daemon-reload; fi
@ -134,10 +194,13 @@ note "Script directory: $SCRIPT_DIR"
note "Repository root: $REPO_ROOT"
for req in "$TEMPLATE_ENFORCE" "$TEMPLATE_UNLOCK" "$UNIT_GUARD_SERVICE"; do
[[ -f $req ]] || { err "Missing template: $req"; exit 1; }
[[ -f $req ]] || {
err "Missing template: $req"
exit 1
}
done
if [[ ! -f "$HOSTS" ]]; then
if [[ ! -f $HOSTS ]]; then
err "$HOSTS does not exist. Run your hosts/install.sh first."
exit 1
fi
@ -146,7 +209,7 @@ fi
# Snapshot
######################################################################
if [[ $DO_SNAPSHOT -eq 1 ]]; then
if [[ -f "$CANON" && $FORCE_SNAPSHOT -eq 0 ]]; then
if [[ -f $CANON && $FORCE_SNAPSHOT -eq 0 ]]; then
note "Canonical snapshot exists (use --force-snapshot to overwrite)"
else
msg "Creating canonical snapshot at $CANON"
@ -182,14 +245,12 @@ fi
if [[ $INSTALL_SHELL_HOOKS -eq 1 ]]; then
msg "Installing shell history suppression hooks for unlock command"
# Pattern matches commands invoking unlock-hosts (with or without sudo) & setup script force snapshot
FILTER_PATTERN='(^|;|&&|\|\|)\s*(sudo\s+)?(/usr/local/sbin/)?unlock-hosts(\s|;|$)'
# Zsh: use zshaddhistory function
if command -v zsh >/dev/null 2>&1; then
if command -v zsh > /dev/null 2>&1; then
if [[ $DRY_RUN -eq 1 ]]; then
echo "DRY-RUN: would create $ZSH_FILTER_SNIPPET"
else
cat > "$ZSH_FILTER_SNIPPET" <<'ZEOF'
cat > "$ZSH_FILTER_SNIPPET" << 'ZEOF'
# Added by hosts guard setup – suppress unlock-hosts commands from Zsh history
autoload -Uz add-zsh-hook 2>/dev/null || true
_hosts_guard_history_filter() {
@ -213,11 +274,11 @@ ZEOF
fi
# Bash: rely on HISTCONTROL and PROMPT_COMMAND filter
if command -v bash >/dev/null 2>&1; then
if command -v bash > /dev/null 2>&1; then
if [[ $DRY_RUN -eq 1 ]]; then
echo "DRY-RUN: would create $BASH_FILTER_SNIPPET"
else
cat > "$BASH_FILTER_SNIPPET" <<'BEOF'
cat > "$BASH_FILTER_SNIPPET" << 'BEOF'
# Added by hosts guard setup – suppress unlock-hosts commands from Bash history
export HISTCONTROL=ignoredups:erasedups
_hosts_guard_hist_filter() {
@ -253,7 +314,7 @@ if [[ $ADD_ALIAS_STUB -eq 1 ]]; then
if [[ $DRY_RUN -eq 1 ]]; then
echo "DRY-RUN: would create $PROFILE_STUB"
else
cat > "$PROFILE_STUB" <<'ASTUB'
cat > "$PROFILE_STUB" << 'ASTUB'
# Added by hosts guard setup – discourages casual use of unlock-hosts name
if command -v unlock-hosts >/dev/null 2>&1; then
alias unlock-hosts='command_not_found_handle 2>/dev/null || echo "Use: sudo /usr/local/sbin/unlock-hosts (logged & delayed)"'
@ -267,16 +328,17 @@ fi
# Audit rule to record executions (requires auditd)
######################################################################
if [[ $INSTALL_AUDIT_RULE -eq 1 ]]; then
if command -v auditctl >/dev/null 2>&1; then
AUDIT_RULE="-w /usr/local/sbin/unlock-hosts -p x -k hosts_unlock"
if auditctl -l 2>/dev/null | grep -Fq "/usr/local/sbin/unlock-hosts"; then
if command -v auditctl > /dev/null 2>&1; then
audit_rule_str="-w /usr/local/sbin/unlock-hosts -p x -k hosts_unlock"
audit_rule_args=(-w /usr/local/sbin/unlock-hosts -p x -k hosts_unlock)
if auditctl -l 2> /dev/null | grep -Fq "/usr/local/sbin/unlock-hosts"; then
note "Audit rule already present"
else
run auditctl $AUDIT_RULE || warn "Failed to add audit rule (runtime)"
run auditctl "${audit_rule_args[@]}" || warn "Failed to add audit rule (runtime)"
if [[ $DRY_RUN -eq 1 ]]; then
echo "DRY-RUN: would create /etc/audit/rules.d/hosts_unlock.rules"
else
echo "$AUDIT_RULE" > /etc/audit/rules.d/hosts_unlock.rules
echo "$audit_rule_str" > /etc/audit/rules.d/hosts_unlock.rules
fi
fi
else
@ -323,22 +385,22 @@ fi
######################################################################
echo
msg "Hosts guard setup complete"
echo "Canonical copy: $CANON"
echo "Enforce script: $INSTALL_ENFORCE"
echo "Unlock command: sudo $INSTALL_UNLOCK"
echo "Delay (seconds): $DELAY"
echo "Auto-revert path watch: $([[ $ENABLE_PATH -eq 1 ]] && echo enabled || echo disabled)"
echo "Read-only bind mount: $([[ $ENABLE_BIND -eq 1 ]] && echo enabled || echo disabled)"
echo "Canonical copy: $CANON"
echo "Enforce script: $INSTALL_ENFORCE"
echo "Unlock command: sudo $INSTALL_UNLOCK"
echo "Delay (seconds): $DELAY"
echo "Auto-revert path watch: $([[ $ENABLE_PATH -eq 1 ]] && echo enabled || echo disabled)"
echo "Read-only bind mount: $([[ $ENABLE_BIND -eq 1 ]] && echo enabled || echo disabled)"
echo "Shell history suppression: $([[ $INSTALL_SHELL_HOOKS -eq 1 ]] && echo enabled || echo disabled)"
echo "Audit rule: $([[ $INSTALL_AUDIT_RULE -eq 1 ]] && echo enabled || echo disabled)"
echo "Alias stub: $([[ $ADD_ALIAS_STUB -eq 1 ]] && echo enabled || echo disabled)"
echo
echo "Test flow:"
echo " sudo sed -i '1s/.*/# tamper test/' /etc/hosts # Should revert automatically"
echo " sudo $INSTALL_UNLOCK # Intentional edit workflow"
echo "Test flow:"
echo " sudo sed -i '1s/.*/# tamper test/' /etc/hosts # Should revert automatically"
echo " sudo $INSTALL_UNLOCK # Intentional edit workflow"
echo
echo "Uninstall:"
echo " sudo $0 --uninstall"
echo "(Optional) Skip shell history hooks: --no-shell-hooks"
echo "Uninstall:"
echo " sudo $0 --uninstall"
echo "(Optional) Skip shell history hooks: --no-shell-hooks"
echo
exit 0