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Include extra attributes in SubjectAccessReview #13170

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Include extra attributes in SubjectAccessReview #13170

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4 changes: 3 additions & 1 deletion pkg/k8s/authz.go
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Original file line number Diff line number Diff line change
Expand Up @@ -48,11 +48,13 @@ func ResourceAuthz(
func ResourceAuthzForUser(
ctx context.Context,
client kubernetes.Interface,
namespace, verb, group, version, resource, subresource, name, user string, userGroups []string) error {
namespace, verb, group, version, resource, subresource, name, user string, userGroups []string, extra map[string]authV1.ExtraValue) error {
sar := &authV1.SubjectAccessReview{
Spec: authV1.SubjectAccessReviewSpec{
User: user,
Groups: userGroups,
Extra: extra,

ResourceAttributes: &authV1.ResourceAttributes{
Namespace: namespace,
Verb: verb,
Expand Down
25 changes: 20 additions & 5 deletions viz/tap/api/handlers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import (
"encoding/json"
"fmt"
"net/http"
"net/url"
"strings"

"github.com/go-openapi/spec"
Expand All @@ -17,17 +18,19 @@ import (
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/sirupsen/logrus"
"google.golang.org/grpc/metadata"
authV1 "k8s.io/api/authorization/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/apimachinery/pkg/version"
)

type handler struct {
k8sAPI *k8s.API
usernameHeader string
groupHeader string
grpcTapServer pb.TapServer
log *logrus.Entry
k8sAPI *k8s.API
usernameHeader string
groupHeader string
extraHeaderPrefix string
grpcTapServer pb.TapServer
log *logrus.Entry
}

// TODO: share with api_handlers.go
Expand Down Expand Up @@ -123,6 +126,17 @@ func (h *handler) handleTap(w http.ResponseWriter, req *http.Request, p httprout
namespace, resource, name, h.usernameHeader, h.groupHeader,
)

extra := make(map[string]authV1.ExtraValue)
for key, values := range req.Header {
if strings.HasPrefix(key, h.extraHeaderPrefix) {
key, err := url.QueryUnescape(strings.TrimPrefix(key, h.extraHeaderPrefix))

if err != nil {
extra[key] = values
}
}
}

// TODO: it's possible this SubjectAccessReview is redundant, consider
// removing, more info at https://github.com/linkerd/linkerd2/issues/3182
err := pkgK8s.ResourceAuthzForUser(
Expand All @@ -137,6 +151,7 @@ func (h *handler) handleTap(w http.ResponseWriter, req *http.Request, p httprout
name,
req.Header.Get(h.usernameHeader),
req.Header.Values(h.groupHeader),
extra,
)
if err != nil {
err = fmt.Errorf("tap authorization failed (%w), visit %s for more information", err, pkg.TapRbacURL)
Expand Down
36 changes: 23 additions & 13 deletions viz/tap/api/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ func NewServer(
}
}()

clientCAPem, allowedNames, usernameHeader, groupHeader, err := serverAuth(ctx, k8sAPI)
clientCAPem, allowedNames, usernameHeader, groupHeader, extraHeaderPrefix, err := serverAuth(ctx, k8sAPI)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -80,11 +80,12 @@ func NewServer(

var emptyCert atomic.Value
h := &handler{
k8sAPI: k8sAPI,
usernameHeader: usernameHeader,
groupHeader: groupHeader,
grpcTapServer: grpcTapServer,
log: log,
k8sAPI: k8sAPI,
usernameHeader: usernameHeader,
groupHeader: groupHeader,
extraHeaderPrefix: extraHeaderPrefix,
grpcTapServer: grpcTapServer,
log: log,
}

lis, err := net.Listen("tcp", addr)
Expand Down Expand Up @@ -164,28 +165,28 @@ func (a *Server) validate(req *http.Request) error {
// authentication.
// kubectl -n kube-system get cm/extension-apiserver-authentication
// accessible via the extension-apiserver-authentication-reader role
func serverAuth(ctx context.Context, k8sAPI *k8s.API) (string, []string, string, string, error) {
func serverAuth(ctx context.Context, k8sAPI *k8s.API) (string, []string, string, string, string, error) {

cm, err := k8sAPI.Client.CoreV1().
ConfigMaps(metav1.NamespaceSystem).
Get(ctx, pkgk8s.ExtensionAPIServerAuthenticationConfigMapName, metav1.GetOptions{})
if err != nil {
return "", nil, "", "", fmt.Errorf("failed to load [%s] config: %w", pkgk8s.ExtensionAPIServerAuthenticationConfigMapName, err)
return "", nil, "", "", "", fmt.Errorf("failed to load [%s] config: %w", pkgk8s.ExtensionAPIServerAuthenticationConfigMapName, err)
}

clientCAPem, ok := cm.Data[pkgk8s.ExtensionAPIServerAuthenticationRequestHeaderClientCAFileKey]
if !ok {
return "", nil, "", "", fmt.Errorf("no client CA cert available for apiextension-server")
return "", nil, "", "", "", fmt.Errorf("no client CA cert available for apiextension-server")
}

allowedNames, err := deserializeStrings(cm.Data["requestheader-allowed-names"])
if err != nil {
return "", nil, "", "", err
return "", nil, "", "", "", err
}

usernameHeaders, err := deserializeStrings(cm.Data["requestheader-username-headers"])
if err != nil {
return "", nil, "", "", err
return "", nil, "", "", "", err
}
usernameHeader := ""
if len(usernameHeaders) > 0 {
Expand All @@ -194,14 +195,23 @@ func serverAuth(ctx context.Context, k8sAPI *k8s.API) (string, []string, string,

groupHeaders, err := deserializeStrings(cm.Data["requestheader-group-headers"])
if err != nil {
return "", nil, "", "", err
return "", nil, "", "", "", err
}
groupHeader := ""
if len(groupHeaders) > 0 {
groupHeader = groupHeaders[0]
}

return clientCAPem, allowedNames, usernameHeader, groupHeader, nil
extraHeaderPrefixes, err := deserializeStrings(cm.Data["requestheader-group-headers"])
if err != nil {
return "", nil, "", "", "", err
}
extraHeaderPrefix := ""
if len(extraHeaderPrefixes) > 0 {
extraHeaderPrefix = extraHeaderPrefixes[0]
}

return clientCAPem, allowedNames, usernameHeader, groupHeader, extraHeaderPrefix, nil
}

// copied from https://github.com/kubernetes/apiserver/blob/781c3cd1b3dc5b6f79c68ab0d16fe544600421ef/pkg/server/options/authentication.go#L360
Expand Down
29 changes: 17 additions & 12 deletions viz/tap/api/server_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,13 @@ import (

func TestAPIServerAuth(t *testing.T) {
expectations := []struct {
k8sRes []string
clientCAPem string
allowedNames []string
usernameHeader string
groupHeader string
err error
k8sRes []string
clientCAPem string
allowedNames []string
usernameHeader string
groupHeader string
extraHeaderPrefix string
err error
}{
{
err: fmt.Errorf("failed to load [%s] config: configmaps %q not found", k8sutils.ExtensionAPIServerAuthenticationConfigMapName, k8sutils.ExtensionAPIServerAuthenticationConfigMapName),
Expand All @@ -44,11 +45,12 @@ data:
requestheader-username-headers: '["X-Remote-User"]'
`,
},
clientCAPem: "requestheader-client-ca-file",
allowedNames: []string{"name1", "name2"},
usernameHeader: "X-Remote-User",
groupHeader: "X-Remote-Group",
err: nil,
clientCAPem: "requestheader-client-ca-file",
allowedNames: []string{"name1", "name2"},
usernameHeader: "X-Remote-User",
groupHeader: "X-Remote-Group",
extraHeaderPrefix: "X-Remote-Extra-",
err: nil,
},
}

Expand All @@ -62,7 +64,7 @@ data:
t.Fatalf("NewFakeAPI returned an error: %s", err)
}

clientCAPem, allowedNames, usernameHeader, groupHeader, err := serverAuth(ctx, k8sAPI)
clientCAPem, allowedNames, usernameHeader, groupHeader, extraHeaderPrefix, err := serverAuth(ctx, k8sAPI)

if err != nil && exp.err != nil {
if err.Error() != exp.err.Error() {
Expand All @@ -86,6 +88,9 @@ data:
if groupHeader != exp.groupHeader {
t.Errorf("apiServerAuth returned unexpected groupHeader: %q, expected: %q", groupHeader, exp.groupHeader)
}
if extraHeaderPrefix != exp.extraHeaderPrefix {
t.Errorf("apiServerAuth returned unexpected extraHeaderPrefix: %q, expected: %q", extraHeaderPrefix, exp.extraHeaderPrefix)
}
})
}
}
Expand Down
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