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