hush/vendor/github.com/prometheus/procfs/net_tls_stat.go
jx12n 4d9a26498e hush: one-time secret links the server cannot read
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.
2026-09-03 00:08:38 -06:00

120 lines
3.4 KiB
Go

// Copyright The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package procfs
import (
"bufio"
"fmt"
"os"
"strconv"
"strings"
)
// TLSStat struct represents data in /proc/net/tls_stat.
// See https://docs.kernel.org/networking/tls.html#statistics
type TLSStat struct {
// number of TX sessions currently installed where host handles cryptography
TLSCurrTxSw int
// number of RX sessions currently installed where host handles cryptography
TLSCurrRxSw int
// number of TX sessions currently installed where NIC handles cryptography
TLSCurrTxDevice int
// number of RX sessions currently installed where NIC handles cryptography
TLSCurrRxDevice int
//number of TX sessions opened with host cryptography
TLSTxSw int
//number of RX sessions opened with host cryptography
TLSRxSw int
// number of TX sessions opened with NIC cryptography
TLSTxDevice int
// number of RX sessions opened with NIC cryptography
TLSRxDevice int
// record decryption failed (e.g. due to incorrect authentication tag)
TLSDecryptError int
// number of RX resyncs sent to NICs handling cryptography
TLSRxDeviceResync int
// number of RX records which had to be re-decrypted due to TLS_RX_EXPECT_NO_PAD mis-prediction. Note that this counter will also increment for non-data records.
TLSDecryptRetry int
// number of data RX records which had to be re-decrypted due to TLS_RX_EXPECT_NO_PAD mis-prediction.
TLSRxNoPadViolation int
}
// NewTLSStat reads the tls_stat statistics.
func NewTLSStat() (TLSStat, error) {
fs, err := NewFS(DefaultMountPoint)
if err != nil {
return TLSStat{}, err
}
return fs.NewTLSStat()
}
// NewTLSStat reads the tls_stat statistics.
func (fs FS) NewTLSStat() (TLSStat, error) {
file, err := os.Open(fs.proc.Path("net/tls_stat"))
if err != nil {
return TLSStat{}, err
}
defer file.Close()
var (
tlsstat = TLSStat{}
s = bufio.NewScanner(file)
)
for s.Scan() {
fields := strings.Fields(s.Text())
if len(fields) != 2 {
return TLSStat{}, fmt.Errorf("%w: %q line %q", ErrFileParse, file.Name(), s.Text())
}
name := fields[0]
value, err := strconv.Atoi(fields[1])
if err != nil {
return TLSStat{}, err
}
switch name {
case "TlsCurrTxSw":
tlsstat.TLSCurrTxSw = value
case "TlsCurrRxSw":
tlsstat.TLSCurrRxSw = value
case "TlsCurrTxDevice":
tlsstat.TLSCurrTxDevice = value
case "TlsCurrRxDevice":
tlsstat.TLSCurrRxDevice = value
case "TlsTxSw":
tlsstat.TLSTxSw = value
case "TlsRxSw":
tlsstat.TLSRxSw = value
case "TlsTxDevice":
tlsstat.TLSTxDevice = value
case "TlsRxDevice":
tlsstat.TLSRxDevice = value
case "TlsDecryptError":
tlsstat.TLSDecryptError = value
case "TlsRxDeviceResync":
tlsstat.TLSRxDeviceResync = value
case "TlsDecryptRetry":
tlsstat.TLSDecryptRetry = value
case "TlsRxNoPadViolation":
tlsstat.TLSRxNoPadViolation = value
}
}
return tlsstat, s.Err()
}