mirror of
https://github.com/edgelesssys/constellation.git
synced 2024-12-13 18:04:20 -05:00
4284f892ce
* rename to attestationconfigapi + put client and fetcher inside pkg * rename api/version to versionsapi and put fetcher + client inside pkg * rename AttestationConfigAPIFetcher to Fetcher
313 lines
8.4 KiB
Go
313 lines
8.4 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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package main
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import (
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"bytes"
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"context"
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"fmt"
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"go/ast"
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"go/parser"
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"go/printer"
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"go/token"
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"log"
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"net/http"
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"net/url"
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"os"
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"path"
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"sort"
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"strconv"
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"strings"
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"github.com/edgelesssys/constellation/v2/internal/api/versionsapi"
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"github.com/edgelesssys/constellation/v2/internal/attestation/measurements"
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"github.com/edgelesssys/constellation/v2/internal/cloud/cloudprovider"
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"github.com/edgelesssys/constellation/v2/internal/sigstore"
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"github.com/edgelesssys/constellation/v2/internal/variant"
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"golang.org/x/tools/go/ast/astutil"
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)
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// this tool is used to generate hardcoded measurements for the enterprise build.
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// Measurements are embedded in the constellation cli.
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func main() {
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const imageFilePath = "../../config/image_enterprise.go"
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defaultImage, err := imageVersionFromFile(imageFilePath)
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if err != nil {
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log.Fatalf("error parsing image version from %s: %s", imageFilePath, err)
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}
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log.Printf("Generating measurements for %s\n", defaultImage)
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const outFilePath = "./measurements_enterprise.go"
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ctx := context.Background()
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fset := token.NewFileSet()
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outFile, err := parser.ParseFile(fset, outFilePath, nil, parser.ParseComments)
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if err != nil {
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log.Fatal(err)
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}
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rekor, err := sigstore.NewRekor()
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if err != nil {
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log.Fatal(err)
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}
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var returnStmtCtr int
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newFile := astutil.Apply(outFile, func(cursor *astutil.Cursor) bool {
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n := cursor.Node()
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// find all variables of the form <provider>_<variant> and replace them with updated measurements
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// see ../measurements_enterprise.go for an example
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if clause, ok := n.(*ast.ValueSpec); ok && len(clause.Names) == 1 && len(clause.Values) == 1 {
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varName := clause.Names[0].Name
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_, ok := clause.Values[0].(*ast.CompositeLit)
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if !ok {
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return true
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}
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nameParts := strings.Split(varName, "_")
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if len(nameParts) != 2 {
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return true
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}
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provider := cloudprovider.FromString(nameParts[0])
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variant, err := attestationVariantFromGoIdentifier(nameParts[1])
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if err != nil {
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log.Fatalf("error parsing variant %s: %s", nameParts[1], err)
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}
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log.Println("Found", variant)
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returnStmtCtr++
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// retrieve and validate measurements for the given CSP and image
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measuremnts := mustGetMeasurements(ctx, rekor, provider, variant, defaultImage)
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// replace the return statement with a composite literal containing the validated measurements
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clause.Values[0] = measurementsCompositeLiteral(measuremnts)
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}
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return true
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}, nil,
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)
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if returnStmtCtr == 0 {
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log.Fatal("no measurements updated")
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}
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var buf bytes.Buffer
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printConfig := printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 8}
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if err = printConfig.Fprint(&buf, fset, newFile); err != nil {
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log.Fatalf("error formatting file %s: %s", outFilePath, err)
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}
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if err := os.WriteFile(outFilePath, buf.Bytes(), 0o644); err != nil {
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log.Fatalf("error writing file %s: %s", outFilePath, err)
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}
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log.Println("Successfully generated hashes.")
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}
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// mustGetMeasurements fetches the measurements for the given image and CSP and verifies them.
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func mustGetMeasurements(ctx context.Context, verifier rekorVerifier, provider cloudprovider.Provider, attestationVariant variant.Variant, image string) measurements.M {
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measurementsURL, err := measurementURL(image, "measurements.json")
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if err != nil {
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panic(err)
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}
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signatureURL, err := measurementURL(image, "measurements.json.sig")
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if err != nil {
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panic(err)
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}
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imageVersion, err := versionsapi.NewVersionFromShortPath(image, versionsapi.VersionKindImage)
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if err != nil {
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panic(err)
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}
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log.Println("Fetching measurements from", measurementsURL, "and signature from", signatureURL)
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var fetchedMeasurements measurements.M
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hash, err := fetchedMeasurements.FetchAndVerify(
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ctx, http.DefaultClient, sigstore.CosignVerifier{},
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measurementsURL,
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signatureURL,
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imageVersion,
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provider,
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attestationVariant,
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)
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if err != nil {
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panic(err)
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}
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if err := sigstore.VerifyWithRekor(ctx, imageVersion, verifier, hash); err != nil {
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panic(err)
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}
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return fetchedMeasurements
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}
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// measurementURL returns the URL for the measurements file for the given image and CSP.
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func measurementURL(image, file string) (*url.URL, error) {
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version, err := versionsapi.NewVersionFromShortPath(image, versionsapi.VersionKindImage)
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if err != nil {
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return nil, fmt.Errorf("parsing image name: %w", err)
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}
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return url.Parse(
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version.ArtifactsURL(versionsapi.APIV2) + path.Join("/image", file),
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)
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}
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// byteArrayCompositeLit returns a *ast.CompositeLit representing a byte array literal.
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// The returned literal is of the form:
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// []byte{ 0x01, 0x02, 0x03, ... }.
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func byteArrayCompositeLit(hex []byte) *ast.CompositeLit {
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var elts []ast.Expr
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// create list of byte literals
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for _, b := range hex {
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elts = append(elts, &ast.BasicLit{
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Kind: token.INT,
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Value: fmt.Sprintf("0x%02x", b),
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})
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}
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// create the composite literal
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// containing the byte literals as part of an []byte slice
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return &ast.CompositeLit{
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Type: &ast.ArrayType{
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Elt: ast.NewIdent("byte"),
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},
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Elts: elts,
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}
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}
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// measurementsEntryKeyValueExpr returns a *ast.KeyValueExpr representing a measurements.Measurement entry.
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// The returned expression is of the form:
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//
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// 0: {
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// Expected: []byte{ 0x01, 0x02, 0x03, ... },
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// WarnOnly: false,
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// },
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func measurementsEntryKeyValueExpr(pcr uint32, measuremnt measurements.Measurement) *ast.KeyValueExpr {
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key := fmt.Sprintf("%d", pcr)
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var validationOptString string
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if measuremnt.ValidationOpt {
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validationOptString = "WarnOnly"
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} else {
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validationOptString = "Enforce"
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}
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return &ast.KeyValueExpr{
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Key: &ast.BasicLit{
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Kind: token.INT,
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Value: key,
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},
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Value: &ast.CompositeLit{
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Elts: []ast.Expr{
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&ast.KeyValueExpr{
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Key: &ast.Ident{Name: "Expected"},
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Value: byteArrayCompositeLit(measuremnt.Expected),
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},
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&ast.KeyValueExpr{
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Key: &ast.Ident{Name: "ValidationOpt"},
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Value: &ast.Ident{Name: validationOptString},
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},
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},
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},
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}
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}
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// measurementsCompositeLiteral returns a *ast.CompositeLit representing a measurements.M literal.
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// The returned literal is of the form:
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//
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// M{
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// 0: {
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// Expected: []byte{ 0x01, 0x02, 0x03, ... },
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// WarnOnly: false,
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// },
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// 1: {
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// Expected: []byte{ 0x01, 0x02, 0x03, ... },
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// WarnOnly: false,
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// },
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// ...
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// }
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func measurementsCompositeLiteral(measurements measurements.M) *ast.CompositeLit {
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var elts []ast.Expr
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pcrs := make([]uint32, 0, len(measurements))
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for pcr := range measurements {
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pcrs = append(pcrs, pcr)
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}
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sort.Slice(pcrs, func(i, j int) bool { return pcrs[i] < pcrs[j] })
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for _, pcr := range pcrs {
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kvExpr := measurementsEntryKeyValueExpr(pcr, measurements[pcr])
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elts = append(elts, kvExpr)
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}
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return &ast.CompositeLit{
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Type: &ast.Ident{
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Name: "M",
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},
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Elts: elts,
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}
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}
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func attestationVariantFromGoIdentifier(identifier string) (variant.Variant, error) {
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switch identifier {
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case "Dummy":
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return variant.Dummy{}, nil
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case "AWSNitroTPM":
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return variant.AWSNitroTPM{}, nil
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case "GCPSEVES":
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return variant.GCPSEVES{}, nil
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case "AzureSEVSNP":
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return variant.AzureSEVSNP{}, nil
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case "AzureTrustedLaunch":
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return variant.AzureTrustedLaunch{}, nil
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case "QEMUVTPM":
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return variant.QEMUVTPM{}, nil
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case "QEMUTDX":
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return variant.QEMUTDX{}, nil
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}
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return nil, fmt.Errorf("unknown identifier: %q", identifier)
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}
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func imageVersionFromFile(path string) (string, error) {
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fset := token.NewFileSet()
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imageFile, err := parser.ParseFile(fset, path, nil, parser.ParseComments)
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if err != nil {
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log.Fatal(err)
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}
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var defaultImage string
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_ = astutil.Apply(imageFile, func(cursor *astutil.Cursor) bool {
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n := cursor.Node()
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// find const of the form defaultImage = "<version>"
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if clause, ok := n.(*ast.ValueSpec); ok && len(clause.Names) == 1 && len(clause.Values) == 1 {
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constName := clause.Names[0].Name
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constValue, ok := clause.Values[0].(*ast.BasicLit)
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if !ok || constValue.Kind != token.STRING {
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return true
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}
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if constName != "defaultImage" {
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return true
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}
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unquoted, err := strconv.Unquote(constValue.Value)
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if err != nil {
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log.Printf("error parsing defaultImage: %s", err)
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return true
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}
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defaultImage = unquoted
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}
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return true
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}, nil,
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)
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if defaultImage == "" {
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return "", fmt.Errorf("no defaultImage found")
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}
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return defaultImage, nil
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}
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type rekorVerifier interface {
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SearchByHash(context.Context, string) ([]string, error)
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VerifyEntry(context.Context, string, string) error
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}
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