92 lines
3.3 KiB
Java
92 lines
3.3 KiB
Java
/*
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* Copyright (C) 2017 Schürmann & Breitmoser GbR
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.sufficientlysecure.keychain.util;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.InputStream;
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import android.annotation.TargetApi;
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import android.content.ContentResolver;
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import android.content.res.AssetFileDescriptor;
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import android.net.Uri;
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import android.os.Build.VERSION_CODES;
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import android.os.ParcelFileDescriptor;
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import android.system.ErrnoException;
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import android.system.Os;
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import android.system.StructStat;
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import timber.log.Timber;
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/**
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* FileHelper methods which use Lollipop-exclusive API.
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* Some of the methods and static fields used here cause VerifyErrors because
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* they do not exist in pre-lollipop API, so they must be kept in a
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* lollipop-only class. All methods here should only be called by FileHelper,
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* and consequently have package visibility.
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*/
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@TargetApi(VERSION_CODES.LOLLIPOP)
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class FileHelperLollipop {
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/**
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* A replacement for ContentResolver.openInputStream() that does not allow the usage of
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* "file" Uris that point to private files owned by the application only.
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*
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* This is not allowed:
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* am start -a android.intent.action.SEND -t text/plain -n
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* "org.sufficientlysecure.keychain.debug/org.sufficientlysecure.keychain.ui.EncryptFilesActivity" --eu
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* android.intent.extra.STREAM
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* file:///data/data/org.sufficientlysecure.keychain.debug/databases/openkeychain.db
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*
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* @throws FileNotFoundException
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*/
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static InputStream openInputStreamSafe(ContentResolver resolver, Uri uri)
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throws FileNotFoundException {
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String scheme = uri.getScheme();
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if (ContentResolver.SCHEME_FILE.equals(scheme)) {
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ParcelFileDescriptor pfd = ParcelFileDescriptor.open(
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new File(uri.getPath()), ParcelFileDescriptor.parseMode("r"));
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try {
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final StructStat st = Os.fstat(pfd.getFileDescriptor());
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if (st.st_uid == android.os.Process.myUid()) {
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Timber.e("File is owned by the application itself, aborting!");
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throw new FileNotFoundException("Unable to create stream");
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}
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} catch (ErrnoException e) {
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Timber.e("fstat() failed: " + e);
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throw new FileNotFoundException("fstat() failed");
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}
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AssetFileDescriptor fd = new AssetFileDescriptor(pfd, 0, -1);
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try {
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return fd.createInputStream();
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} catch (IOException e) {
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throw new FileNotFoundException("Unable to create stream");
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}
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} else {
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return resolver.openInputStream(uri);
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}
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}
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}
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