SELinuxPolicyInstallReceiver.java revision 9a492393dfb69050b2a4a8b5205e8d2fc24fcd43 
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.util.Base64;
24import android.util.Slog;
25
26import java.io.BufferedInputStream;
27import java.io.File;
28import java.io.FileInputStream;
29import java.io.IOException;
30
31import libcore.io.ErrnoException;
32import libcore.io.IoUtils;
33import libcore.io.Libcore;
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
44    public SELinuxPolicyInstallReceiver() {
45        super("/data/security/bundle", "sepolicy_bundle", "metadata/", "version");
46    }
47
48    private void backupContexts(File contexts) {
49        new File(contexts, seappContextsPath).renameTo(
50                new File(contexts, seappContextsPath + "_backup"));
51
52        new File(contexts, propertyContextsPath).renameTo(
53                new File(contexts, propertyContextsPath + "_backup"));
54
55        new File(contexts, fileContextsPath).renameTo(
56                new File(contexts, fileContextsPath + "_backup"));
57
58        new File(contexts, sepolicyPath).renameTo(
59                new File(contexts, sepolicyPath + "_backup"));
60    }
61
62    private void copyUpdate(File contexts) {
63        new File(updateDir, seappContextsPath).renameTo(new File(contexts, seappContextsPath));
64        new File(updateDir, propertyContextsPath).renameTo(new File(contexts, propertyContextsPath));
65        new File(updateDir, fileContextsPath).renameTo(new File(contexts, fileContextsPath));
66        new File(updateDir, sepolicyPath).renameTo(new File(contexts, sepolicyPath));
67    }
68
69    private int readInt(BufferedInputStream reader) throws IOException {
70        int value = 0;
71        for (int i=0; i < 4; i++) {
72            value = (value << 8) | reader.read();
73        }
74        return value;
75    }
76
77    private int[] readChunkLengths(BufferedInputStream bundle) throws IOException {
78        int[] chunks = new int[4];
79        chunks[0] = readInt(bundle);
80        chunks[1] = readInt(bundle);
81        chunks[2] = readInt(bundle);
82        chunks[3] = readInt(bundle);
83        return chunks;
84    }
85
86    private void installFile(File destination, BufferedInputStream stream, int length)
87            throws IOException {
88        byte[] chunk = new byte[length];
89        stream.read(chunk, 0, length);
90        writeUpdate(updateDir, destination, Base64.decode(chunk, Base64.DEFAULT));
91    }
92
93    private void unpackBundle() throws IOException {
94        BufferedInputStream stream = new BufferedInputStream(new FileInputStream(updateContent));
95        try {
96            int[] chunkLengths = readChunkLengths(stream);
97            installFile(new File(updateDir, seappContextsPath), stream, chunkLengths[0]);
98            installFile(new File(updateDir, propertyContextsPath), stream, chunkLengths[1]);
99            installFile(new File(updateDir, fileContextsPath), stream, chunkLengths[2]);
100            installFile(new File(updateDir, sepolicyPath), stream, chunkLengths[3]);
101        } finally {
102            IoUtils.closeQuietly(stream);
103        }
104    }
105
106    private void applyUpdate() throws IOException, ErrnoException {
107        Slog.i(TAG, "Applying SELinux policy");
108        File contexts = new File(updateDir.getParentFile(), "contexts");
109        File current = new File(updateDir.getParentFile(), "current");
110        File update = new File(updateDir.getParentFile(), "update");
111        File tmp = new File(updateDir.getParentFile(), "tmp");
112        if (current.exists()) {
113            Libcore.os.symlink(updateDir.getPath(), update.getPath());
114            Libcore.os.rename(update.getPath(), current.getPath());
115        } else {
116            Libcore.os.symlink(updateDir.getPath(), current.getPath());
117        }
118        contexts.mkdirs();
119        backupContexts(contexts);
120        copyUpdate(contexts);
121        Libcore.os.symlink(contexts.getPath(), tmp.getPath());
122        Libcore.os.rename(tmp.getPath(), current.getPath());
123        SystemProperties.set("selinux.reload_policy", "1");
124    }
125
126    @Override
127    protected void postInstall(Context context, Intent intent) {
128        try {
129            unpackBundle();
130            applyUpdate();
131        } catch (IllegalArgumentException e) {
132            Slog.e(TAG, "SELinux policy update malformed: ", e);
133        } catch (IOException e) {
134            Slog.e(TAG, "Could not update selinux policy: ", e);
135        } catch (ErrnoException e) {
136            Slog.e(TAG, "Could not update selinux policy: ", e);
137        }
138    }
139}
140