/
admission.go
225 lines (186 loc) · 7.16 KB
/
admission.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
// Copyright (c) 2020 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package customverbauthorizer
import (
"context"
"fmt"
"io"
"strings"
"github.com/gardener/gardener/pkg/apis/core"
admissioninitializer "github.com/gardener/gardener/pkg/apiserver/admission/initializer"
rbacv1 "k8s.io/api/rbac/v1"
apiequality "k8s.io/apimachinery/pkg/api/equality"
apierrors "k8s.io/apimachinery/pkg/api/errors"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/apiserver/pkg/admission"
"k8s.io/apiserver/pkg/authentication/serviceaccount"
"k8s.io/apiserver/pkg/authentication/user"
"k8s.io/apiserver/pkg/authorization/authorizer"
)
const (
// PluginName is the name of this admission plugin.
PluginName = "CustomVerbAuthorizer"
// CustomVerbModifyProjectTolerationsWhitelist is a constant for the custom verb that allows modifying the
// `.spec.tolerations.whitelist` field in `Project` resources.
CustomVerbModifyProjectTolerationsWhitelist = "modify-spec-tolerations-whitelist"
// CustomVerbProjectUserAccessManagement is a constant for the custom verb that allows to manage human users or
// groups subjects in the `.spec.members` field in `Project` resources.
CustomVerbProjectManageMembers = "manage-members"
)
// Register registers a plugin.
func Register(plugins *admission.Plugins) {
plugins.Register(PluginName, NewFactory)
}
// NewFactory creates a new PluginFactory.
func NewFactory(config io.Reader) (admission.Interface, error) {
return New()
}
// CustomVerbAuthorizer contains an admission handler and listers.
type CustomVerbAuthorizer struct {
*admission.Handler
authorizer authorizer.Authorizer
}
var _ = admissioninitializer.WantsAuthorizer(&CustomVerbAuthorizer{})
// New creates a new CustomVerbAuthorizer admission plugin.
func New() (*CustomVerbAuthorizer, error) {
return &CustomVerbAuthorizer{
Handler: admission.NewHandler(admission.Create, admission.Update),
}, nil
}
// SetAuthorizer gets the authorizer.
func (c *CustomVerbAuthorizer) SetAuthorizer(authorizer authorizer.Authorizer) {
c.authorizer = authorizer
}
// ValidateInitialization checks whether the plugin was correctly initialized.
func (c *CustomVerbAuthorizer) ValidateInitialization() error {
return nil
}
var _ admission.ValidationInterface = &CustomVerbAuthorizer{}
// Validate makes admissions decisions based on custom verbs.
func (c *CustomVerbAuthorizer) Validate(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces) error {
switch a.GetKind().GroupKind() {
case core.Kind("Project"):
return c.admitProjects(ctx, a)
}
return nil
}
func (c *CustomVerbAuthorizer) admitProjects(ctx context.Context, a admission.Attributes) error {
var (
oldObj = &core.Project{}
obj = &core.Project{}
ok bool
)
obj, ok = a.GetObject().(*core.Project)
if !ok {
return apierrors.NewBadRequest("could not convert resource into Project object")
}
if a.GetOperation() == admission.Update {
oldObj, ok = a.GetOldObject().(*core.Project)
if !ok {
return apierrors.NewBadRequest("could not convert old resource into Project object")
}
}
if mustCheckProjectTolerationsWhitelist(oldObj.Spec.Tolerations, obj.Spec.Tolerations) {
return c.authorize(ctx, a, CustomVerbModifyProjectTolerationsWhitelist, "modify .spec.tolerations.whitelist")
}
if mustCheckProjectMembers(oldObj.Spec.Members, obj.Spec.Members, obj.Spec.Owner, a.GetUserInfo()) {
return c.authorize(ctx, a, CustomVerbProjectManageMembers, "manage human users or groups in .spec.members")
}
return nil
}
func (c *CustomVerbAuthorizer) authorize(ctx context.Context, a admission.Attributes, verb, operation string) error {
var (
userInfo = a.GetUserInfo()
resource = a.GetResource()
namespace = a.GetNamespace()
name = a.GetName()
)
decision, _, err := c.authorizer.Authorize(ctx, authorizer.AttributesRecord{
User: userInfo,
APIGroup: resource.Group,
Resource: resource.Resource,
Namespace: namespace,
Name: name,
Verb: verb,
ResourceRequest: true,
})
if err != nil {
return err
}
if decision != authorizer.DecisionAllow {
return admission.NewForbidden(a, fmt.Errorf("user %q is not allowed to %s for %q", userInfo.GetName(), operation, resource.Resource))
}
return nil
}
func mustCheckProjectTolerationsWhitelist(oldTolerations, tolerations *core.ProjectTolerations) bool {
if apiequality.Semantic.DeepEqual(oldTolerations, tolerations) {
return false
}
if oldTolerations == nil && tolerations != nil {
return !apiequality.Semantic.DeepEqual(nil, tolerations.Whitelist)
}
if oldTolerations != nil && tolerations == nil {
return !apiequality.Semantic.DeepEqual(oldTolerations.Whitelist, nil)
}
return !apiequality.Semantic.DeepEqual(oldTolerations.Whitelist, tolerations.Whitelist)
}
func mustCheckProjectMembers(oldMembers, members []core.ProjectMember, owner *rbacv1.Subject, userInfo user.Info) bool {
if apiequality.Semantic.DeepEqual(oldMembers, members) {
return false
}
// If the user submitting this admission request is the owner then it will be/is bound to the `manage-members`
// custom verb anyways, so let's allow him to add/remove human users.
if userIsOwner(userInfo, owner) {
return false
}
var oldHumanUsers, newHumanUsers = findHumanUsers(oldMembers), findHumanUsers(members)
// Remove owner subject from `members` list to always allow it to be added
if owner != nil && isHumanUser(*owner) {
newHumanUsers.Delete(humanMemberKey(*owner))
}
return !oldHumanUsers.Equal(newHumanUsers)
}
func findHumanUsers(members []core.ProjectMember) sets.String {
result := sets.NewString()
for _, member := range members {
if isHumanUser(member.Subject) {
result.Insert(humanMemberKey(member.Subject))
}
}
return result
}
func isHumanUser(subject rbacv1.Subject) bool {
return subject.Kind == rbacv1.UserKind && !strings.HasPrefix(subject.Name, serviceaccount.ServiceAccountUsernamePrefix)
}
func humanMemberKey(subject rbacv1.Subject) string {
return subject.Kind + subject.Name
}
func userIsOwner(userInfo user.Info, owner *rbacv1.Subject) bool {
if owner == nil { // no explicit owner is set, i.e., the creator will be defaulted to the owner
return true
}
switch owner.Kind {
case rbacv1.ServiceAccountKind:
namespace, name, err := serviceaccount.SplitUsername(userInfo.GetName())
if err != nil {
return false
}
return owner.Name == name && owner.Namespace == namespace
case rbacv1.UserKind:
return owner.Name == userInfo.GetName()
case rbacv1.GroupKind:
return sets.NewString(userInfo.GetGroups()...).Has(owner.Name)
}
return false
}