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[WIP] Verify Kubernetes components with cosign #744

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[WIP] Verify Kubernetes components with cosign #744

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5 changes: 4 additions & 1 deletion internal/versions/hash-generator/BUILD.bazel
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,10 @@ go_library(
srcs = ["generate.go"],
importpath = "github.com/edgelesssys/constellation/v2/internal/versions/hash-generator",
visibility = ["//visibility:private"],
deps = ["@org_golang_x_tools//go/ast/astutil"],
deps = [
"//internal/sigstore",
"@org_golang_x_tools//go/ast/astutil",
],
)

go_binary(
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75 changes: 75 additions & 0 deletions internal/versions/hash-generator/generate.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,14 @@ import (
"log"
"net/http"
"os"
"regexp"
"strconv"

"golang.org/x/tools/go/ast/astutil"
)

var kuberntesMinorRegex = regexp.MustCompile(`^.*\.(?P<Minor>\d+)\..*(kubelet|kubeadm|kubectl)+$`)

func mustGetHash(url string) string {
// remove quotes around url
url = url[1 : len(url)-1]
Expand Down Expand Up @@ -78,9 +82,80 @@ func mustGetHash(url string) string {
panic("hash mismatch")
}

// Verify cosign signature if available
// Currently, we verify the signature of kubeadm, kubelet and kubectl with minor version >=1.26.
minorVersion := kuberntesMinorRegex.FindStringSubmatch(url)
if minorVersion == nil {
return fmt.Sprintf("\"sha256:%x\"", fileHash)
}
minorVersionIndex := kuberntesMinorRegex.SubexpIndex("Minor")
if minorVersionIndex != -1 {
minorVersionNumber, err := strconv.Atoi(minorVersion[minorVersionIndex])
if err != nil {
panic(err)
}
if minorVersionNumber >= 26 {
content, err := io.ReadAll(resp.Body)
if err != nil {
panic(err)
}
if err := verifyCosignSignature(content, url); err != nil {
panic(err)
}
}
}

return fmt.Sprintf("\"sha256:%x\"", fileHash)
}

func verifyCosignSignature(content []byte, url string) error {
// Get the signature
req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url+".sig", nil)
if err != nil {
panic(err)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer resp.Body.Close()

// Check server response
if resp.StatusCode != http.StatusOK {
panic("bad status: " + resp.Status)
}

sig, err := io.ReadAll(resp.Body)
if err != nil {
panic(err)
}

// Get the certificate
req, err = http.NewRequestWithContext(context.Background(), http.MethodGet, url+".cert", nil)
if err != nil {
panic(err)
}
resp, err = http.DefaultClient.Do(req)
if err != nil {
panic(err)
}
defer resp.Body.Close()

// Check server response
if resp.StatusCode != http.StatusOK {
panic("bad status: " + resp.Status)
}

base64Cert, err := io.ReadAll(resp.Body)
if err != nil {
panic(err)
}

// TODO: implement https://github.com/sigstore/cosign/blob/v2.2.0/cmd/cosign/cli/verify/verify_blob.go keyless verification

return verifier.VerifySignature(content, sig)
}

func main() {
fmt.Println("Generating hashes...")

Expand Down