From d8b68e3ccc2c859f20f08041024af5be0565601b Mon Sep 17 00:00:00 2001
From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Date: Tue, 14 Feb 2023 15:32:14 +0900
Subject: [PATCH] Stop using math/rand.Read and rand.Seed (deprecated in Go
 1.20)

From golangci-lint:

> SA1019: rand.Read has been deprecated since Go 1.20 because it
>shouldn't be used: For almost all use cases, crypto/rand.Read is more
>appropriate. (staticcheck)

> SA1019: rand.Seed has been deprecated since Go 1.20 and an alternative
>has been available since Go 1.0: Programs that call Seed and then expect
>a specific sequence of results from the global random source (using
>functions such as Int) can be broken when a dependency changes how
>much it consumes from the global random source. To avoid such breakages,
>programs that need a specific result sequence should use
>NewRand(NewSource(seed)) to obtain a random generator that other
>packages cannot access. (staticcheck)

See also:

- https://pkg.go.dev/math/rand@go1.20#Read
- https://pkg.go.dev/math/rand@go1.20#Seed

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
---
 archive/compression/compression_test.go |  2 +-
 cmd/containerd/main.go                  |  3 +-
 cmd/ctr/main.go                         |  3 +-
 content/helpers.go                      |  4 +--
 content/local/store.go                  |  4 +--
 content/local/store_test.go             |  5 +--
 diff/walking/differ.go                  |  2 +-
 leases/id.go                            |  2 +-
 mount/losetup_linux.go                  |  4 +--
 pkg/cri/util/id.go                      |  2 +-
 pkg/kmutex/kmutex_test.go               | 13 +++----
 pkg/randutil/randutil.go                | 48 +++++++++++++++++++++++++
 pkg/seed/seed.go                        |  5 +++
 pkg/unpack/unpacker.go                  |  2 +-
 rootfs/apply.go                         |  2 +-
 snapshots/testsuite/helpers.go          |  4 +--
 snapshots/testsuite/testsuite.go        |  4 +--
 17 files changed, 80 insertions(+), 29 deletions(-)
 create mode 100644 pkg/randutil/randutil.go

diff --git a/archive/compression/compression_test.go b/archive/compression/compression_test.go
index 4de650335..fe1a62e35 100644
--- a/archive/compression/compression_test.go
+++ b/archive/compression/compression_test.go
@@ -20,8 +20,8 @@ import (
 	"bytes"
 	"compress/gzip"
 	"context"
+	"crypto/rand"
 	"io"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"runtime"
diff --git a/cmd/containerd/main.go b/cmd/containerd/main.go
index 887e8158a..ccd41c3c0 100644
--- a/cmd/containerd/main.go
+++ b/cmd/containerd/main.go
@@ -23,12 +23,13 @@ import (
 
 	"github.com/containerd/containerd/cmd/containerd/command"
 	"github.com/containerd/containerd/pkg/hasher"
-	"github.com/containerd/containerd/pkg/seed"
+	"github.com/containerd/containerd/pkg/seed" //nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
 
 	_ "github.com/containerd/containerd/cmd/containerd/builtins"
 )
 
 func init() {
+	//nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
 	seed.WithTimeAndRand()
 	crypto.RegisterHash(crypto.SHA256, hasher.NewSHA256)
 }
diff --git a/cmd/ctr/main.go b/cmd/ctr/main.go
index ca0def515..1845a73ed 100644
--- a/cmd/ctr/main.go
+++ b/cmd/ctr/main.go
@@ -23,13 +23,14 @@ import (
 
 	"github.com/containerd/containerd/cmd/ctr/app"
 	"github.com/containerd/containerd/pkg/hasher"
-	"github.com/containerd/containerd/pkg/seed"
+	"github.com/containerd/containerd/pkg/seed" //nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
 	"github.com/urfave/cli"
 )
 
 var pluginCmds = []cli.Command{}
 
 func init() {
+	//nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
 	seed.WithTimeAndRand()
 	crypto.RegisterHash(crypto.SHA256, hasher.NewSHA256)
 }
diff --git a/content/helpers.go b/content/helpers.go
index f74d72a93..5404109a6 100644
--- a/content/helpers.go
+++ b/content/helpers.go
@@ -21,12 +21,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
 	"sync"
 	"time"
 
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
@@ -123,7 +123,7 @@ func OpenWriter(ctx context.Context, cs Ingester, opts ...WriterOpt) (Writer, er
 			// error or abort. Requires asserting for an ingest manager
 
 			select {
-			case <-time.After(time.Millisecond * time.Duration(rand.Intn(retry))):
+			case <-time.After(time.Millisecond * time.Duration(randutil.Intn(retry))):
 				if retry < 2048 {
 					retry = retry << 1
 				}
diff --git a/content/local/store.go b/content/local/store.go
index 27aff14a4..baae3565b 100644
--- a/content/local/store.go
+++ b/content/local/store.go
@@ -20,7 +20,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -32,6 +31,7 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/filters"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/sirupsen/logrus"
 
 	"github.com/opencontainers/go-digest"
@@ -473,7 +473,7 @@ func (s *store) Writer(ctx context.Context, opts ...content.WriterOpt) (content.
 			lockErr = nil
 			break
 		}
-		time.Sleep(time.Millisecond * time.Duration(rand.Intn(1<<count)))
+		time.Sleep(time.Millisecond * time.Duration(randutil.Intn(1<<count)))
 	}
 
 	if lockErr != nil {
diff --git a/content/local/store_test.go b/content/local/store_test.go
index 35cb143ed..48ad54a0b 100644
--- a/content/local/store_test.go
+++ b/content/local/store_test.go
@@ -20,10 +20,10 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"crypto/rand"
 	_ "crypto/sha256" // required for digest package
 	"fmt"
 	"io"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -35,6 +35,7 @@ import (
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/content/testsuite"
 	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/containerd/containerd/pkg/testutil"
 
 	"github.com/opencontainers/go-digest"
@@ -268,7 +269,7 @@ func generateBlobs(t checker, nblobs, maxsize int64) map[digest.Digest][]byte {
 	blobs := map[digest.Digest][]byte{}
 
 	for i := int64(0); i < nblobs; i++ {
-		p := make([]byte, rand.Int63n(maxsize))
+		p := make([]byte, randutil.Int63n(maxsize))
 
 		if _, err := rand.Read(p); err != nil {
 			t.Fatal(err)
diff --git a/diff/walking/differ.go b/diff/walking/differ.go
index 8d40a461f..784d41139 100644
--- a/diff/walking/differ.go
+++ b/diff/walking/differ.go
@@ -18,11 +18,11 @@ package walking
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/base64"
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
 	"time"
 
 	"github.com/containerd/containerd/archive"
diff --git a/leases/id.go b/leases/id.go
index 8781a1d72..8f5dc93f3 100644
--- a/leases/id.go
+++ b/leases/id.go
@@ -17,9 +17,9 @@
 package leases
 
 import (
+	"crypto/rand"
 	"encoding/base64"
 	"fmt"
-	"math/rand"
 	"time"
 )
 
diff --git a/mount/losetup_linux.go b/mount/losetup_linux.go
index 700d1773a..567ebb4e9 100644
--- a/mount/losetup_linux.go
+++ b/mount/losetup_linux.go
@@ -19,11 +19,11 @@ package mount
 import (
 	"errors"
 	"fmt"
-	"math/rand"
 	"os"
 	"strings"
 	"time"
 
+	"github.com/containerd/containerd/pkg/randutil"
 	"golang.org/x/sys/unix"
 )
 
@@ -152,7 +152,7 @@ func setupLoop(backingFile string, param LoopParams) (*os.File, error) {
 			// with EBUSY when trying to set it up.
 			if strings.Contains(err.Error(), ebusyString) {
 				// Fallback a bit to avoid live lock
-				time.Sleep(time.Millisecond * time.Duration(rand.Intn(retry*10)))
+				time.Sleep(time.Millisecond * time.Duration(randutil.Intn(retry*10)))
 				continue
 			}
 			return nil, err
diff --git a/pkg/cri/util/id.go b/pkg/cri/util/id.go
index 90f762ba7..194bab264 100644
--- a/pkg/cri/util/id.go
+++ b/pkg/cri/util/id.go
@@ -17,8 +17,8 @@
 package util
 
 import (
+	"crypto/rand"
 	"encoding/hex"
-	"math/rand"
 )
 
 // GenerateID generates a random unique id.
diff --git a/pkg/kmutex/kmutex_test.go b/pkg/kmutex/kmutex_test.go
index a6fd751ee..6bfff477a 100644
--- a/pkg/kmutex/kmutex_test.go
+++ b/pkg/kmutex/kmutex_test.go
@@ -18,21 +18,16 @@ package kmutex
 
 import (
 	"context"
-	"math/rand"
 	"runtime"
 	"strconv"
 	"sync"
 	"testing"
 	"time"
 
-	"github.com/containerd/containerd/pkg/seed"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/stretchr/testify/assert"
 )
 
-func init() {
-	seed.WithTimeAndRand()
-}
-
 func TestBasic(t *testing.T) {
 	t.Parallel()
 
@@ -60,7 +55,7 @@ func TestBasic(t *testing.T) {
 				waitLock = true
 				break
 			}
-			time.Sleep(time.Duration(rand.Int63n(100)) * time.Millisecond)
+			time.Sleep(time.Duration(randutil.Int63n(100)) * time.Millisecond)
 		}
 		assert.Equal(t, waitLock, true)
 	}
@@ -130,7 +125,7 @@ func TestMultileAcquireOnKeys(t *testing.T) {
 			for i := 0; i < nloops; i++ {
 				km.Lock(ctx, key)
 
-				time.Sleep(time.Duration(rand.Int63n(100)) * time.Nanosecond)
+				time.Sleep(time.Duration(randutil.Int63n(100)) * time.Nanosecond)
 
 				km.Unlock(key)
 			}
@@ -161,7 +156,7 @@ func TestMultiAcquireOnSameKey(t *testing.T) {
 			for i := 0; i < nloops; i++ {
 				km.Lock(ctx, key)
 
-				time.Sleep(time.Duration(rand.Int63n(100)) * time.Nanosecond)
+				time.Sleep(time.Duration(randutil.Int63n(100)) * time.Nanosecond)
 
 				km.Unlock(key)
 			}
diff --git a/pkg/randutil/randutil.go b/pkg/randutil/randutil.go
new file mode 100644
index 000000000..f4b657d7d
--- /dev/null
+++ b/pkg/randutil/randutil.go
@@ -0,0 +1,48 @@
+/*
+   Copyright The containerd 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 randutil provides utilities for [cyrpto/rand].
+package randutil
+
+import (
+	"crypto/rand"
+	"math"
+	"math/big"
+)
+
+// Int63n is similar to [math/rand.Int63n] but uses [crypto/rand.Reader] under the hood.
+func Int63n(n int64) int64 {
+	b, err := rand.Int(rand.Reader, big.NewInt(n))
+	if err != nil {
+		panic(err)
+	}
+	return b.Int64()
+}
+
+// Int63 is similar to [math/rand.Int63] but uses [crypto/rand.Reader] under the hood.
+func Int63() int64 {
+	return Int63n(math.MaxInt64)
+}
+
+// Intn is similar to [math/rand.Intn] but uses [crypto/rand.Reader] under the hood.
+func Intn(n int) int {
+	return int(Int63n(int64(n)))
+}
+
+// Int is similar to [math/rand.Int] but uses [crypto/rand.Reader] under the hood.
+func Int() int {
+	return int(Int63())
+}
diff --git a/pkg/seed/seed.go b/pkg/seed/seed.go
index 4a5829a8e..b8442a88e 100644
--- a/pkg/seed/seed.go
+++ b/pkg/seed/seed.go
@@ -14,6 +14,9 @@
    limitations under the License.
 */
 
+// Package seed provides an initializer for the global [math/rand] seed.
+//
+// Deprecated: Do not rely on the global seed.
 package seed
 
 import (
@@ -23,6 +26,8 @@ import (
 
 // WithTimeAndRand seeds the global math rand generator with nanoseconds
 // XOR'ed with a crypto component if available for uniqueness.
+//
+// Deprecated: Do not rely on the global seed.
 func WithTimeAndRand() {
 	var (
 		b [4]byte
diff --git a/pkg/unpack/unpacker.go b/pkg/unpack/unpacker.go
index 8d72da5ef..3c766403a 100644
--- a/pkg/unpack/unpacker.go
+++ b/pkg/unpack/unpacker.go
@@ -18,11 +18,11 @@ package unpack
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"math/rand"
 	"strconv"
 	"sync"
 	"sync/atomic"
diff --git a/rootfs/apply.go b/rootfs/apply.go
index b3f388e64..35eae6d63 100644
--- a/rootfs/apply.go
+++ b/rootfs/apply.go
@@ -18,9 +18,9 @@ package rootfs
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/base64"
 	"fmt"
-	"math/rand"
 	"time"
 
 	"github.com/containerd/containerd/diff"
diff --git a/snapshots/testsuite/helpers.go b/snapshots/testsuite/helpers.go
index c327b7706..4315db8ff 100644
--- a/snapshots/testsuite/helpers.go
+++ b/snapshots/testsuite/helpers.go
@@ -19,10 +19,10 @@ package testsuite
 import (
 	"context"
 	"fmt"
-	"math/rand"
 	"os"
 
 	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/containerd/containerd/snapshots"
 	"github.com/containerd/continuity/fs/fstest"
 )
@@ -49,7 +49,7 @@ func applyToMounts(m []mount.Mount, work string, a fstest.Applier) (err error) {
 // createSnapshot creates a new snapshot in the snapshotter
 // given an applier to run on top of the given parent.
 func createSnapshot(ctx context.Context, sn snapshots.Snapshotter, parent, work string, a fstest.Applier) (string, error) {
-	n := fmt.Sprintf("%p-%d", a, rand.Int())
+	n := fmt.Sprintf("%p-%d", a, randutil.Int())
 	prepare := fmt.Sprintf("%s-prepare", n)
 
 	m, err := sn.Prepare(ctx, prepare, parent, opt)
diff --git a/snapshots/testsuite/testsuite.go b/snapshots/testsuite/testsuite.go
index cf793d1cd..aa84c3945 100644
--- a/snapshots/testsuite/testsuite.go
+++ b/snapshots/testsuite/testsuite.go
@@ -21,7 +21,6 @@ import (
 	//nolint:revive // go-digest needs the blank import. See https://github.com/opencontainers/go-digest#usage.
 	_ "crypto/sha256"
 	"fmt"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"sort"
@@ -32,6 +31,7 @@ import (
 	"github.com/containerd/containerd/log/logtest"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/containerd/containerd/pkg/testutil"
 	"github.com/containerd/containerd/snapshots"
 	"github.com/containerd/continuity/fs/fstest"
@@ -847,7 +847,7 @@ func checkFileFromLowerLayer(ctx context.Context, t *testing.T, snapshotter snap
 }
 
 func closeTwice(ctx context.Context, t *testing.T, snapshotter snapshots.Snapshotter, work string) {
-	n := fmt.Sprintf("closeTwice-%d", rand.Int())
+	n := fmt.Sprintf("closeTwice-%d", randutil.Int())
 	prepare := fmt.Sprintf("%s-prepare", n)
 
 	// do some dummy ops to modify the snapshotter internal state