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support to declaratively set attestation policy

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This commit is contained in:
Moritz Sanft 2023-06-21 11:45:13 +02:00
parent b25228d175
commit dbc495f164
15 changed files with 82 additions and 188 deletions
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7
cli/internal/cloudcmd/BUILD.bazel
View file

@ -4,11 +4,11 @@ load("//bazel/go:go_test.bzl", "go_test")
go_library(
name = "cloudcmd",
srcs = [
"attestationpolicy.go",
"clients.go",
"cloudcmd.go",
"create.go",
"iam.go",
"patch.go",
"rollback.go",
"terminate.go",
"validators.go",
@ -29,9 +29,6 @@ go_library(
"//internal/config",
"//internal/constants",
"//internal/imagefetcher",
"@com_github_azure_azure_sdk_for_go//profiles/latest/attestation/attestation",
"@com_github_azure_azure_sdk_for_go_sdk_azcore//policy",
"@com_github_azure_azure_sdk_for_go_sdk_azidentity//:azidentity",
"@com_github_hashicorp_terraform_json//:terraform-json",
"@com_github_spf13_cobra//:cobra",
],
@ -40,10 +37,10 @@ go_library(
go_test(
name = "cloudcmd_test",
srcs = [
"attestationpolicy_test.go",
"clients_test.go",
"create_test.go",
"iam_test.go",
"patch_test.go",
"rollback_test.go",
"terminate_test.go",
"validators_test.go",

54
cli/internal/cloudcmd/attestationpolicy.go Normal file
View file

@ -0,0 +1,54 @@
/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package cloudcmd
import (
"encoding/base64"
"fmt"
)
// maaAttestationPolicy is the default attestation policy for Azure VMs on Constellation.
const maaAttestationPolicy = `
version= 1.0;
authorizationrules
{
[type=="x-ms-azurevm-default-securebootkeysvalidated", value==false] => deny();
[type=="x-ms-azurevm-debuggersdisabled", value==false] => deny();
// The line below was edited by the Constellation CLI. Do not edit manually.
//[type=="secureboot", value==false] => deny();
[type=="x-ms-azurevm-signingdisabled", value==false] => deny();
[type=="x-ms-azurevm-dbvalidated", value==false] => deny();
[type=="x-ms-azurevm-dbxvalidated", value==false] => deny();
=> permit();
};
issuancerules
{
};`
// NewAzureMaaAttestationPolicy returns a new AzureAttestationPolicy to use with MAA.
func NewAzureMaaAttestationPolicy() AzureAttestationPolicy {
return AzureAttestationPolicy{
policy: maaAttestationPolicy,
}
}
// AzureAttestationPolicy patches attestation policies on Azure.
type AzureAttestationPolicy struct {
policy string
}
// Encode encodes the base64-encoded attestation policy in the JWS format specified here:
// https://learn.microsoft.com/en-us/azure/attestation/author-sign-policy#creating-the-policy-file-in-json-web-signature-format
func (p AzureAttestationPolicy) Encode() string {
encodedPolicy := base64.RawURLEncoding.EncodeToString([]byte(p.policy))
const header = `{"alg":"none"}`
payload := fmt.Sprintf(`{"AttestationPolicy":"%s"}`, encodedPolicy)
encodedHeader := base64.RawURLEncoding.EncodeToString([]byte(header))
encodedPayload := base64.RawURLEncoding.EncodeToString([]byte(payload))
return fmt.Sprintf("%s.%s.", encodedHeader, encodedPayload)
}

6
cli/internal/cloudcmd/patch_test.go → cli/internal/cloudcmd/attestationpolicy_test.go
View file

@ -11,12 +11,12 @@ import (
"github.com/stretchr/testify/assert"
)
func TestEncodeAttestationPolicy(t *testing.T) {
func TestAzureMaaAttestationPolicyEncode(t *testing.T) {
assert := assert.New(t)
p := AzurePolicyPatcher{}
p := NewAzureMaaAttestationPolicy()
// taken from <resource group url in the azure portal>/providers/Microsoft.Attestation/attestationProviders/<attestation provider name>/mrsg_item2
expected := "eyJhbGciOiJub25lIn0.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."
assert.Equal(expected, p.encodeAttestationPolicy())
assert.Equal(expected, p.Encode())
}

15
cli/internal/cloudcmd/create.go
View file

@ -35,7 +35,6 @@ type Creator struct {
newTerraformClient func(ctx context.Context) (terraformClient, error)
newLibvirtRunner func() libvirtRunner
newRawDownloader func() rawDownloader
policyPatcher policyPatcher
}
// NewCreator creates a new creator.
@ -52,7 +51,6 @@ func NewCreator(out io.Writer) *Creator {
newRawDownloader: func() rawDownloader {
return imagefetcher.NewDownloader()
},
policyPatcher: NewAzurePolicyPatcher(),
}
}
@ -226,6 +224,7 @@ func (c *Creator) createAzure(ctx context.Context, cl terraformClient, opts Crea
ImageID: opts.image,
SecureBoot: *opts.Config.Provider.Azure.SecureBoot,
CreateMAA: opts.Config.GetAttestationConfig().GetVariant().Equal(variant.AzureSEVSNP{}),
MAAPolicy: NewAzureMaaAttestationPolicy().Encode(),
Debug: opts.Config.IsDebugCluster(),
}
@ -243,13 +242,6 @@ func (c *Creator) createAzure(ctx context.Context, cl terraformClient, opts Crea
return clusterid.File{}, err
}
if vars.CreateMAA {
// Patch the attestation policy to allow the cluster to boot while having secure boot disabled.
if err := c.policyPatcher.Patch(ctx, tfOutput.AttestationURL); err != nil {
return clusterid.File{}, err
}
}
return clusterid.File{
CloudProvider: cloudprovider.Azure,
IP: tfOutput.IP,
@ -259,11 +251,6 @@ func (c *Creator) createAzure(ctx context.Context, cl terraformClient, opts Crea
}, nil
}
// policyPatcher interacts with the CSP (currently only applies for Azure) to update the attestation policy.
type policyPatcher interface {
Patch(ctx context.Context, attestationURL string) error
}
// The azurerm Terraform provider enforces its own convention of case sensitivity for Azure URIs which Azure's API itself does not enforce or, even worse, actually returns.
// Let's go loco with case insensitive Regexp here and fix the user input here to be compliant with this arbitrary design decision.
var (

27
cli/internal/cloudcmd/create_test.go
View file

@ -33,7 +33,6 @@ func TestCreator(t *testing.T) {
libvirt *stubLibvirtRunner
provider cloudprovider.Provider
config *config.Config
policyPatcher *stubPolicyPatcher
wantErr bool
wantRollback bool // Use only together with stubClients.
wantTerraformRollback bool // When libvirt fails, don't call into Terraform.
@ -65,7 +64,6 @@ func TestCreator(t *testing.T) {
cfg.RemoveProviderAndAttestationExcept(cloudprovider.Azure)
return cfg
}(),
policyPatcher: &stubPolicyPatcher{},
},
"azure trusted launch": {
tfClient: &stubTerraformClient{ip: ip},
@ -77,18 +75,6 @@ func TestCreator(t *testing.T) {
}
return cfg
}(),
policyPatcher: &stubPolicyPatcher{},
},
"azure new policy patch error": {
tfClient: &stubTerraformClient{ip: ip},
provider: cloudprovider.Azure,
config: func() *config.Config {
cfg := config.Default()
cfg.RemoveProviderAndAttestationExcept(cloudprovider.Azure)
return cfg
}(),
policyPatcher: &stubPolicyPatcher{someErr},
wantErr: true,
},
"azure newTerraformClient error": {
newTfClientErr: someErr,
@ -98,8 +84,7 @@ func TestCreator(t *testing.T) {
cfg.RemoveProviderAndAttestationExcept(cloudprovider.Azure)
return cfg
}(),
policyPatcher: &stubPolicyPatcher{},
wantErr: true,
wantErr: true,
},
"azure create cluster error": {
tfClient: &stubTerraformClient{createClusterErr: someErr},
@ -109,7 +94,6 @@ func TestCreator(t *testing.T) {
cfg.RemoveProviderAndAttestationExcept(cloudprovider.Azure)
return cfg
}(),
policyPatcher: &stubPolicyPatcher{},
wantErr: true,
wantRollback: true,
wantTerraformRollback: true,
@ -213,7 +197,6 @@ func TestCreator(t *testing.T) {
destination: "some-destination",
}
},
policyPatcher: tc.policyPatcher,
}
opts := CreateOptions{
@ -247,14 +230,6 @@ func TestCreator(t *testing.T) {
}
}
type stubPolicyPatcher struct {
patchErr error
}
func (s stubPolicyPatcher) Patch(_ context.Context, _ string) error {
return s.patchErr
}
func TestNormalizeAzureURIs(t *testing.T) {
testCases := map[string]struct {
in terraform.AzureClusterVariables

94
cli/internal/cloudcmd/patch.go
View file

@ -1,94 +0,0 @@
/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package cloudcmd
import (
"context"
"encoding/base64"
"fmt"
"net/http"
"github.com/Azure/azure-sdk-for-go/profiles/latest/attestation/attestation"
azpolicy "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
)
// NewAzurePolicyPatcher returns a new AzurePolicyPatcher.
func NewAzurePolicyPatcher() AzurePolicyPatcher {
return AzurePolicyPatcher{}
}
// AzurePolicyPatcher patches attestation policies on Azure.
type AzurePolicyPatcher struct{}
// Patch updates the attestation policy to the base64-encoded attestation policy JWT for the given attestation URL.
// https://learn.microsoft.com/en-us/azure/attestation/author-sign-policy#next-steps
func (p AzurePolicyPatcher) Patch(ctx context.Context, attestationURL string) error {
// hacky way to update the MAA attestation policy. This should be changed as soon as either the Terraform provider supports it
// or the Go SDK gets updated to a recent API version.
// https://github.com/hashicorp/terraform-provider-azurerm/issues/20804
cred, err := azidentity.NewDefaultAzureCredential(nil)
if err != nil {
return fmt.Errorf("retrieving default Azure credentials: %w", err)
}
token, err := cred.GetToken(ctx, azpolicy.TokenRequestOptions{
Scopes: []string{"https://attest.azure.net/.default"},
})
if err != nil {
return fmt.Errorf("retrieving token from default Azure credentials: %w", err)
}
client := attestation.NewPolicyClient()
// azureGuest is the id for the "Azure VM" attestation type. Other types are documented here:
// https://learn.microsoft.com/en-us/rest/api/attestation/policy/set
req, err := client.SetPreparer(ctx, attestationURL, "azureGuest", p.encodeAttestationPolicy())
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token.Token))
if err != nil {
return fmt.Errorf("preparing request: %w", err)
}
resp, err := client.Send(req)
if err != nil {
return fmt.Errorf("sending request: %w", err)
}
resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("updating attestation policy: unexpected status code: %s", resp.Status)
}
return nil
}
// encodeAttestationPolicy encodes the base64-encoded attestation policy in the JWS format specified here:
// https://learn.microsoft.com/en-us/azure/attestation/author-sign-policy#creating-the-policy-file-in-json-web-signature-format
func (p AzurePolicyPatcher) encodeAttestationPolicy() string {
const policy = `
version= 1.0;
authorizationrules
{
[type=="x-ms-azurevm-default-securebootkeysvalidated", value==false] => deny();
[type=="x-ms-azurevm-debuggersdisabled", value==false] => deny();
// The line below was edited by the Constellation CLI. Do not edit manually.
//[type=="secureboot", value==false] => deny();
[type=="x-ms-azurevm-signingdisabled", value==false] => deny();
[type=="x-ms-azurevm-dbvalidated", value==false] => deny();
[type=="x-ms-azurevm-dbxvalidated", value==false] => deny();
=> permit();
};
issuancerules
{
};`
encodedPolicy := base64.RawURLEncoding.EncodeToString([]byte(policy))
const header = `{"alg":"none"}`
payload := fmt.Sprintf(`{"AttestationPolicy":"%s"}`, encodedPolicy)
encodedHeader := base64.RawURLEncoding.EncodeToString([]byte(header))
encodedPayload := base64.RawURLEncoding.EncodeToString([]byte(payload))
return fmt.Sprintf("%s.%s.", encodedHeader, encodedPayload)
}