SELinuxPolicyInstallReceiver.java revision 332f35813e9860b8469b0f804f2b576daa0c823f 
1/*
2 * Copyright (C) 2013 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
17package com.android.server.updates;
18
19import android.content.Context;
20import android.content.Intent;
21import android.os.SystemProperties;
22import android.provider.Settings;
23import android.system.ErrnoException;
24import android.system.Os;
25import android.util.Base64;
26import android.util.Slog;
27
28import java.io.BufferedInputStream;
29import java.io.File;
30import java.io.FileInputStream;
31import java.io.IOException;
32
33import libcore.io.IoUtils;
34
35public class SELinuxPolicyInstallReceiver extends ConfigUpdateInstallReceiver {
36
37    private static final String TAG = "SELinuxPolicyInstallReceiver";
38
39    private static final String sepolicyPath = "sepolicy";
40    private static final String fileContextsPath = "file_contexts";
41    private static final String propertyContextsPath = "property_contexts";
42    private static final String seappContextsPath = "seapp_contexts";
43    private static final String versionPath = "selinux_version";
44    private static final String macPermissionsPath = "mac_permissions.xml";
45
46    public SELinuxPolicyInstallReceiver() {
47        super("/data/security/bundle", "sepolicy_bundle", "metadata/", "version");
48    }
49
50    private void backupContexts(File contexts) {
51        new File(contexts, versionPath).renameTo(
52                new File(contexts, versionPath + "_backup"));
53
54        new File(contexts, macPermissionsPath).renameTo(
55                new File(contexts, macPermissionsPath + "_backup"));
56
57        new File(contexts, seappContextsPath).renameTo(
58                new File(contexts, seappContextsPath + "_backup"));
59
60        new File(contexts, propertyContextsPath).renameTo(
61                new File(contexts, propertyContextsPath + "_backup"));
62
63        new File(contexts, fileContextsPath).renameTo(
64                new File(contexts, fileContextsPath + "_backup"));
65
66        new File(contexts, sepolicyPath).renameTo(
67                new File(contexts, sepolicyPath + "_backup"));
68    }
69
70    private void copyUpdate(File contexts) {
71        new File(updateDir, versionPath).renameTo(new File(contexts, versionPath));
72        new File(updateDir, macPermissionsPath).renameTo(new File(contexts, macPermissionsPath));
73        new File(updateDir, seappContextsPath).renameTo(new File(contexts, seappContextsPath));
74        new File(updateDir, propertyContextsPath).renameTo(new File(contexts, propertyContextsPath));
75        new File(updateDir, fileContextsPath).renameTo(new File(contexts, fileContextsPath));
76        new File(updateDir, sepolicyPath).renameTo(new File(contexts, sepolicyPath));
77    }
78
79    private int readInt(BufferedInputStream reader) throws IOException {
80        int value = 0;
81        for (int i=0; i < 4; i++) {
82            value = (value << 8) | reader.read();
83        }
84        return value;
85    }
86
87    private int[] readChunkLengths(BufferedInputStream bundle) throws IOException {
88        int[] chunks = new int[6];
89        chunks[0] = readInt(bundle);
90        chunks[1] = readInt(bundle);
91        chunks[2] = readInt(bundle);
92        chunks[3] = readInt(bundle);
93        chunks[4] = readInt(bundle);
94        chunks[5] = readInt(bundle);
95        return chunks;
96    }
97
98    private void installFile(File destination, BufferedInputStream stream, int length)
99            throws IOException {
100        byte[] chunk = new byte[length];
101        stream.read(chunk, 0, length);
102        writeUpdate(updateDir, destination, Base64.decode(chunk, Base64.DEFAULT));
103    }
104
105    private void unpackBundle() throws IOException {
106        BufferedInputStream stream = new BufferedInputStream(new FileInputStream(updateContent));
107        try {
108            int[] chunkLengths = readChunkLengths(stream);
109            installFile(new File(updateDir, versionPath), stream, chunkLengths[0]);
110            installFile(new File(updateDir, macPermissionsPath), stream, chunkLengths[1]);
111            installFile(new File(updateDir, seappContextsPath), stream, chunkLengths[2]);
112            installFile(new File(updateDir, propertyContextsPath), stream, chunkLengths[3]);
113            installFile(new File(updateDir, fileContextsPath), stream, chunkLengths[4]);
114            installFile(new File(updateDir, sepolicyPath), stream, chunkLengths[5]);
115        } finally {
116            IoUtils.closeQuietly(stream);
117        }
118    }
119
120    private void applyUpdate() throws IOException, ErrnoException {
121        Slog.i(TAG, "Applying SELinux policy");
122        File contexts = new File(updateDir.getParentFile(), "contexts");
123        File current = new File(updateDir.getParentFile(), "current");
124        File update = new File(updateDir.getParentFile(), "update");
125        File tmp = new File(updateDir.getParentFile(), "tmp");
126        if (current.exists()) {
127            Os.symlink(updateDir.getPath(), update.getPath());
128            Os.rename(update.getPath(), current.getPath());
129        } else {
130            Os.symlink(updateDir.getPath(), current.getPath());
131        }
132        contexts.mkdirs();
133        backupContexts(contexts);
134        copyUpdate(contexts);
135        Os.symlink(contexts.getPath(), tmp.getPath());
136        Os.rename(tmp.getPath(), current.getPath());
137        SystemProperties.set("selinux.reload_policy", "1");
138    }
139
140    @Override
141    protected void postInstall(Context context, Intent intent) {
142        try {
143            unpackBundle();
144            applyUpdate();
145        } catch (IllegalArgumentException e) {
146            Slog.e(TAG, "SELinux policy update malformed: ", e);
147        } catch (IOException e) {
148            Slog.e(TAG, "Could not update selinux policy: ", e);
149        } catch (ErrnoException e) {
150            Slog.e(TAG, "Could not update selinux policy: ", e);
151        }
152    }
153}
154