4d9a26498e
Paste a secret, get a link, send it. The first person to open it and press
Reveal sees the secret; the link dies at that moment. The recipient needs a
browser and nothing else — no account, no client, no installed tooling.
The server cannot read what it stores. AES-256-GCM happens in the browser and
the key lives in the URL fragment, which browsers never transmit, so hushd
holds ciphertext and no key material. That is a property of where the key sits
rather than a promise about our conduct, which is why there is deliberately no
endpoint accepting a plaintext secret and no server-side-encryption fallback:
two guarantees behind one URL would be worse than one honest guarantee.
Three decisions carry the design:
* GET /s/{id} touches NO storage, not even to check existence. Slack, Teams,
WhatsApp, iMessage and Outlook Safe Links all fetch a URL before a human
sees it, so destroying on GET would destroy most secrets in transit and the
recipient's "already used" would be indistinguishable from interception.
Only POST /reveal consumes. Bot user-agent detection is an arms race;
removing the side effect from GET is not. Pinned by
TestGettingTheRevealPageNeverConsumesTheSecret.
* Destruction is one Redis GETDEL, which is atomic. GET-then-DEL has a window
where two simultaneous readers both win, and for a one-time secret that
window is the product. The store contract demands atomicity and the same
concurrency test runs against both implementations.
* Missing, already-revealed, expired and evicted are ONE indistinguishable
410. Separating them would confirm to a prober that a given link was real.
The secret id IS the capability, so secret.ID is a struct whose every
accidental path — %v, %s, String(), slog, json.Marshal — emits a redacted
handle or refuses, and the raw value needs an explicit Value(). The first
version tried to prevent leaks by implementing no String() at all; its own test
caught that Go's fmt prints unexported fields anyway, so forbidding the method
had removed the control rather than the leak.
Operationally: structured JSON on stdout in the fleet's wire format, which
Vector already collects with no annotation; six hush_* metrics on the chassis
registry with no id, IP or path in any label; five alert rules wired into
vmalert. The public Ingress enumerates /, /s/ and /api/ so /metrics, /healthz
and /readyz share the port but are unreachable from the internet — no
basic-auth middleware to maintain and get wrong.
Dependencies are vendored because go-chassis is private: the Woodpecker test
step and the in-cluster Kaniko build both run -mod=vendor with GOPROXY=off and
hold no git credential.
cmd/hush-mcp is a stdio MCP server doing the same client-side crypto locally,
so using hush from an agent preserves the same guarantee as using it from a
browser.
119 lines
3.3 KiB
Go
119 lines
3.3 KiB
Go
// Copyright The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package procfs
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"strings"
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"github.com/prometheus/procfs/internal/util"
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)
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// A ConntrackStatEntry represents one line from net/stat/nf_conntrack
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// and contains netfilter conntrack statistics at one CPU core.
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type ConntrackStatEntry struct {
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Entries uint64
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Searched uint64
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Found uint64
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New uint64
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Invalid uint64
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Ignore uint64
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Delete uint64
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DeleteList uint64
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Insert uint64
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InsertFailed uint64
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Drop uint64
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EarlyDrop uint64
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SearchRestart uint64
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}
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// ConntrackStat retrieves netfilter's conntrack statistics, split by CPU cores.
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func (fs FS) ConntrackStat() ([]ConntrackStatEntry, error) {
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return readConntrackStat(fs.proc.Path("net", "stat", "nf_conntrack"))
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}
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// Parses a slice of ConntrackStatEntries from the given filepath.
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func readConntrackStat(path string) ([]ConntrackStatEntry, error) {
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// This file is small and can be read with one syscall.
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b, err := util.ReadFileNoStat(path)
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if err != nil {
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// Do not wrap this error so the caller can detect os.IsNotExist and
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// similar conditions.
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return nil, err
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}
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stat, err := parseConntrackStat(bytes.NewReader(b))
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if err != nil {
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return nil, fmt.Errorf("%w: Cannot read file: %v: %w", ErrFileRead, path, err)
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}
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return stat, nil
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}
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// Reads the contents of a conntrack statistics file and parses a slice of ConntrackStatEntries.
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func parseConntrackStat(r io.Reader) ([]ConntrackStatEntry, error) {
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var entries []ConntrackStatEntry
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scanner := bufio.NewScanner(r)
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scanner.Scan()
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for scanner.Scan() {
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fields := strings.Fields(scanner.Text())
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conntrackEntry, err := parseConntrackStatEntry(fields)
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if err != nil {
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return nil, err
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}
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entries = append(entries, *conntrackEntry)
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}
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return entries, nil
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}
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// Parses a ConntrackStatEntry from given array of fields.
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func parseConntrackStatEntry(fields []string) (*ConntrackStatEntry, error) {
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entries, err := util.ParseHexUint64s(fields)
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if err != nil {
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return nil, fmt.Errorf("%w: Cannot parse entry: %d: %w", ErrFileParse, entries, err)
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}
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numEntries := len(entries)
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if numEntries < 16 || numEntries > 17 {
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return nil,
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fmt.Errorf("%w: invalid conntrackstat entry, invalid number of fields: %d", ErrFileParse, numEntries)
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}
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stats := &ConntrackStatEntry{
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Entries: *entries[0],
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Searched: *entries[1],
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Found: *entries[2],
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New: *entries[3],
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Invalid: *entries[4],
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Ignore: *entries[5],
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Delete: *entries[6],
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DeleteList: *entries[7],
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Insert: *entries[8],
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InsertFailed: *entries[9],
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Drop: *entries[10],
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EarlyDrop: *entries[11],
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}
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// Ignore missing search_restart on Linux < 2.6.35.
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if numEntries == 17 {
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stats.SearchRestart = *entries[16]
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}
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return stats, nil
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}
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