1 /*
2  * Copyright (C) 2020 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.content.integrity;
18 
19 import android.annotation.NonNull;
20 import android.os.Parcel;
21 import android.os.Parcelable;
22 
23 import java.util.Map;
24 
25 /**
26  * An atomic formula that evaluates to true if the installer of the current install is specified in
27  * the "allowed installer" field in the android manifest. Note that an empty "allowed installer" by
28  * default means containing all possible installers.
29  *
30  * @hide
31  */
32 public class InstallerAllowedByManifestFormula extends IntegrityFormula implements Parcelable {
33 
34     public static final String INSTALLER_CERTIFICATE_NOT_EVALUATED = "";
35 
InstallerAllowedByManifestFormula()36     public InstallerAllowedByManifestFormula() {
37     }
38 
InstallerAllowedByManifestFormula(Parcel in)39     private InstallerAllowedByManifestFormula(Parcel in) {
40     }
41 
42     @NonNull
43     public static final Creator<InstallerAllowedByManifestFormula> CREATOR =
44             new Creator<InstallerAllowedByManifestFormula>() {
45                 @Override
46                 public InstallerAllowedByManifestFormula createFromParcel(Parcel in) {
47                     return new InstallerAllowedByManifestFormula(in);
48                 }
49 
50                 @Override
51                 public InstallerAllowedByManifestFormula[] newArray(int size) {
52                     return new InstallerAllowedByManifestFormula[size];
53                 }
54             };
55 
56     @Override
getTag()57     public int getTag() {
58         return IntegrityFormula.INSTALLER_ALLOWED_BY_MANIFEST_FORMULA_TAG;
59     }
60 
61     @Override
matches(AppInstallMetadata appInstallMetadata)62     public boolean matches(AppInstallMetadata appInstallMetadata) {
63         Map<String, String> allowedInstallersAndCertificates =
64                 appInstallMetadata.getAllowedInstallersAndCertificates();
65         return allowedInstallersAndCertificates.isEmpty()
66                 || installerInAllowedInstallersFromManifest(
67                 appInstallMetadata, allowedInstallersAndCertificates);
68     }
69 
70     @Override
isAppCertificateFormula()71     public boolean isAppCertificateFormula() {
72         return false;
73     }
74 
75     @Override
isAppCertificateLineageFormula()76     public boolean isAppCertificateLineageFormula() {
77         return false;
78     }
79 
80     @Override
isInstallerFormula()81     public boolean isInstallerFormula() {
82         return true;
83     }
84 
installerInAllowedInstallersFromManifest( AppInstallMetadata appInstallMetadata, Map<String, String> allowedInstallersAndCertificates)85     private static boolean installerInAllowedInstallersFromManifest(
86             AppInstallMetadata appInstallMetadata,
87             Map<String, String> allowedInstallersAndCertificates) {
88         String installerPackage = appInstallMetadata.getInstallerName();
89 
90         if (!allowedInstallersAndCertificates.containsKey(installerPackage)) {
91             return false;
92         }
93 
94         // If certificate is not specified in the manifest, we do not check it.
95         if (!allowedInstallersAndCertificates.get(installerPackage)
96                 .equals(INSTALLER_CERTIFICATE_NOT_EVALUATED)) {
97             return appInstallMetadata.getInstallerCertificates()
98                     .contains(
99                             allowedInstallersAndCertificates
100                                     .get(appInstallMetadata.getInstallerName()));
101         }
102 
103         return true;
104     }
105 
106     @Override
describeContents()107     public int describeContents() {
108         return 0;
109     }
110 
111     @Override
writeToParcel(Parcel dest, int flags)112     public void writeToParcel(Parcel dest, int flags) {
113     }
114 }
115