admin
f31a76f788
B3: Lookup re-reads the append-only store once on a miss (cross-process coherence with the one-shot provisioner; size short-circuit bounds the cost; behind the TokenAuthority seam). B2: fenced mkdir -p /var/lib/vz/snippets before the snippet install + the one narrow sudoers grant. Both red-proofed; drill findings DRILL-day0-cleanroom-2026-07-03 B3/B2. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6
78 lines
3.5 KiB
Go
78 lines
3.5 KiB
Go
package guesthook
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import (
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"context"
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"fmt"
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"os"
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"path/filepath"
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"strconv"
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"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
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)
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// Install/registration of the pre-start hook. The wrapper lives in a PVE `snippets`-enabled storage dir
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// (the `local` storage maps to /var/lib/vz/snippets) and is referenced per-guest by its volid.
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const (
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// SnippetDir is the local-storage snippets directory PVE serves hookscripts from.
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SnippetDir = "/var/lib/vz/snippets"
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// SnippetName is the wrapper filename.
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SnippetName = "felhom-guest-hook.sh"
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// HookVolID is the volid form `pct set --hookscript` expects.
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HookVolID = "local:snippets/" + SnippetName
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// AgentBin is the installed agent binary the wrapper delegates to.
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AgentBin = "/usr/local/bin/felhom-agent"
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)
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// SnippetPath is the absolute path of the installed wrapper.
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var SnippetPath = filepath.Join(SnippetDir, SnippetName)
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// snippetBody is the tiny wrapper PVE execs as `<script> <vmid> <phase>`. It delegates to the agent
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// binary so the heal LOGIC is the unit-tested Go, never duplicated (divergence-proof) shell. Executable.
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const snippetBody = `#!/bin/sh
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# felhom-agent guest pre-start self-heal hook (C1 net). PVE calls: <script> <vmid> <phase>.
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exec ` + AgentBin + ` guest-hook "$1" "$2"
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`
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// InstallSnippet writes the pre-start hook wrapper into the PVE snippets dir (idempotent, root-owned,
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// executable). The agent runs as a non-root service user, so it writes an agent-writable temp file then
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// `install`s it host-root (same pattern as the bootstrap mount + dnsmasq drop-ins). Safe to call repeatedly.
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// The temp file is a RANDOM-named os.CreateTemp (audit B1): a fixed, predictable /tmp name could be
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// pre-created by another local user and rewritten between our write and root's install (TOCTOU into a
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// root-executed hookscript). The final mode comes from `install -m`, so the 0600 temp is fine.
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func InstallSnippet(ctx context.Context, runner proxmox.Runner) error {
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f, err := os.CreateTemp("", "felhom-guest-hook-*.sh")
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if err != nil {
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return fmt.Errorf("guesthook: create temp snippet: %w", err)
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}
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tmp := f.Name()
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defer os.Remove(tmp)
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if _, err := f.WriteString(snippetBody); err != nil {
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f.Close()
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return fmt.Errorf("guesthook: write temp snippet: %w", err)
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}
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if err := f.Close(); err != nil {
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return fmt.Errorf("guesthook: close temp snippet: %w", err)
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}
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// Ensure the snippets dir exists FIRST (B2, DRILL-day0-cleanroom-2026-07-03): a fresh PVE has
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// no /var/lib/vz/snippets, and `install` (without -D) won't create the parent — the whole
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// hook install silently failed on a freshly-bootstrapped box. Fenced root op like the install
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// itself; idempotent.
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if _, stderr, err := runner.Run(ctx, "mkdir", "-p", SnippetDir); err != nil {
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return fmt.Errorf("guesthook: ensure snippets dir %s: %w: %s", SnippetDir, err, string(stderr))
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}
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if _, stderr, err := runner.Run(ctx, "install", "-m", "0755", "--", tmp, SnippetPath); err != nil {
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return fmt.Errorf("guesthook: install snippet to %s: %w: %s", SnippetPath, err, string(stderr))
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}
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return nil
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}
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// Register points a guest at the pre-start hook (`pct set <vmid> --hookscript <volid>`). Idempotent —
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// re-setting the same hookscript is a no-op. Safe on a running guest (a config edit, not a start, so no
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// start-lock contention).
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func Register(ctx context.Context, runner proxmox.Runner, vmid int) error {
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if _, stderr, err := runner.Run(ctx, "pct", "set", strconv.Itoa(vmid), "--hookscript", HookVolID); err != nil {
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return fmt.Errorf("guesthook: register hookscript on %d: %w: %s", vmid, err, string(stderr))
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}
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return nil
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}
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