111 lines
3.4 KiB
Go
111 lines
3.4 KiB
Go
package handler
|
|
|
|
import (
|
|
"context"
|
|
"encoding/json"
|
|
"fmt"
|
|
"io"
|
|
"net/http"
|
|
"path/filepath"
|
|
|
|
"github.com/docker/attest/pkg/attest"
|
|
"github.com/docker/attest/pkg/oci"
|
|
"github.com/docker/attest/pkg/policy"
|
|
"github.com/docker/attest/pkg/tuf"
|
|
"github.com/open-policy-agent/frameworks/constraint/pkg/externaldata"
|
|
"github.com/open-policy-agent/gatekeeper-external-data-provider/internal/embed"
|
|
"github.com/open-policy-agent/gatekeeper-external-data-provider/pkg/utils"
|
|
"k8s.io/klog/v2"
|
|
)
|
|
|
|
func Handler(w http.ResponseWriter, req *http.Request) {
|
|
// only accept POST requests
|
|
if req.Method != http.MethodPost {
|
|
utils.SendResponse(nil, "only POST is allowed", w)
|
|
return
|
|
}
|
|
|
|
// read request body
|
|
requestBody, err := io.ReadAll(req.Body)
|
|
if err != nil {
|
|
utils.SendResponse(nil, fmt.Sprintf("unable to read request body: %v", err), w)
|
|
return
|
|
}
|
|
|
|
klog.InfoS("received request", "body", requestBody)
|
|
|
|
// parse request body
|
|
var providerRequest externaldata.ProviderRequest
|
|
err = json.Unmarshal(requestBody, &providerRequest)
|
|
if err != nil {
|
|
utils.SendResponse(nil, fmt.Sprintf("unable to unmarshal request body: %v", err), w)
|
|
return
|
|
}
|
|
|
|
results := make([]externaldata.Item, 0)
|
|
|
|
// create a tuf client
|
|
tufOutputPath := filepath.Join("/tuf_temp", ".docker", "tuf")
|
|
tufClient, err := createTufClient(tufOutputPath)
|
|
if err != nil {
|
|
utils.SendResponse(nil, err.Error(), w)
|
|
}
|
|
|
|
// iterate over all keys
|
|
for _, key := range providerRequest.Request.Keys {
|
|
// create a resolver for remote attestations
|
|
platform := "linux/amd64"
|
|
resolver := &oci.RegistryResolver{
|
|
Image: key, // path to image index in OCI registry containing image attestations
|
|
Platform: platform, // platform of subject image (image that attestations are being verified against)
|
|
}
|
|
|
|
// configure policy options
|
|
opts := &policy.PolicyOptions{
|
|
TufClient: tufClient,
|
|
LocalTargetsDir: filepath.Join("/tuf_temp", ".docker", "policy"), // location to store policy files downloaded from TUF
|
|
LocalPolicyDir: "", // overrides TUF policy for local policy files if set
|
|
}
|
|
|
|
// verify attestations
|
|
ctx := context.TODO()
|
|
debug := true
|
|
ctx = policy.WithPolicyEvaluator(ctx, policy.NewRegoEvaluator(debug))
|
|
policy, err := attest.Verify(ctx, opts, resolver)
|
|
if err != nil {
|
|
results = append(results, externaldata.Item{
|
|
Key: key,
|
|
Error: "admit: false, error: " + err.Error(),
|
|
})
|
|
continue
|
|
}
|
|
if policy {
|
|
klog.Infof("policy passed: %v\n", policy)
|
|
// valid key will have "_valid" appended as return value
|
|
results = append(results, externaldata.Item{
|
|
Key: key,
|
|
Value: "admit: true, message: policy passed",
|
|
})
|
|
continue // passed policy
|
|
}
|
|
// no policy found for image
|
|
klog.Infof("no policy for image")
|
|
results = append(results, externaldata.Item{
|
|
Key: key,
|
|
Value: "admit: true, message: no policy",
|
|
})
|
|
}
|
|
utils.SendResponse(&results, "", w)
|
|
}
|
|
|
|
func createTufClient(outputPath string) (*tuf.TufClient, error) {
|
|
// using oci tuf metadata and targets
|
|
metadataURI := "registry-1.docker.io/docker/tuf-metadata:latest"
|
|
targetsURI := "registry-1.docker.io/docker/tuf-targets"
|
|
// example using http tuf metadata and targets
|
|
// metadataURI := "https://docker.github.io/tuf-staging/metadata"
|
|
// targetsURI := "https://docker.github.io/tuf-staging/targets"
|
|
|
|
return tuf.NewTufClient(embed.StagingRoot, outputPath, metadataURI, targetsURI)
|
|
}
|