hush/vendor/github.com/prometheus/procfs/proc_statm.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

118 lines
3.1 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 (
"os"
"strconv"
"strings"
"github.com/prometheus/procfs/internal/util"
)
// - https://man7.org/linux/man-pages/man5/proc_pid_statm.5.html
// ProcStatm Provides memory usage information for a process, measured in memory pages.
// Read from /proc/[pid]/statm.
type ProcStatm struct {
// The process ID.
PID int
// total program size (same as VmSize in status)
Size uint64
// resident set size (same as VmRSS in status)
Resident uint64
// number of resident shared pages (i.e., backed by a file)
Shared uint64
// text (code)
Text uint64
// library (unused since Linux 2.6; always 0)
Lib uint64
// data + stack
Data uint64
// dirty pages (unused since Linux 2.6; always 0)
Dt uint64
}
// NewStatm returns the current status information of the process.
//
// Deprecated: Use p.Statm() instead.
func (p Proc) NewStatm() (ProcStatm, error) {
return p.Statm()
}
// Statm returns the current memory usage information of the process.
func (p Proc) Statm() (ProcStatm, error) {
data, err := util.ReadFileNoStat(p.path("statm"))
if err != nil {
return ProcStatm{}, err
}
statmSlice, err := parseStatm(data)
if err != nil {
return ProcStatm{}, err
}
procStatm := ProcStatm{
PID: p.PID,
Size: statmSlice[0],
Resident: statmSlice[1],
Shared: statmSlice[2],
Text: statmSlice[3],
Lib: statmSlice[4],
Data: statmSlice[5],
Dt: statmSlice[6],
}
return procStatm, nil
}
// parseStatm return /proc/[pid]/statm data to uint64 slice.
func parseStatm(data []byte) ([]uint64, error) {
var statmSlice []uint64
statmItems := strings.Fields(string(data))
for i := range statmItems {
statmItem, err := strconv.ParseUint(statmItems[i], 10, 64)
if err != nil {
return nil, err
}
statmSlice = append(statmSlice, statmItem)
}
return statmSlice, nil
}
// SizeBytes returns the process of total program size in bytes.
func (s ProcStatm) SizeBytes() uint64 {
return s.Size * uint64(os.Getpagesize())
}
// ResidentBytes returns the process of resident set size in bytes.
func (s ProcStatm) ResidentBytes() uint64 {
return s.Resident * uint64(os.Getpagesize())
}
// SHRBytes returns the process of share memory size in bytes.
func (s ProcStatm) SHRBytes() uint64 {
return s.Shared * uint64(os.Getpagesize())
}
// TextBytes returns the process of text (code) size in bytes.
func (s ProcStatm) TextBytes() uint64 {
return s.Text * uint64(os.Getpagesize())
}
// DataBytes returns the process of data + stack size in bytes.
func (s ProcStatm) DataBytes() uint64 {
return s.Data * uint64(os.Getpagesize())
}