Merge "[hardening] Use read() instead of mmap() for incfs files" into sc-dev (e32f0d1c) · Commits · e / os / android_frameworks_base

core/java/android/os/incremental/IncrementalManager.java

+9 −0

Original line number	Diff line number	Diff line
		@@ -30,6 +30,7 @@ import android.util.SparseArray;
		import com.android.internal.annotations.GuardedBy;

		import java.io.File;
		import java.io.FileDescriptor;
		import java.io.IOException;
		import java.lang.annotation.Retention;
		import java.lang.annotation.RetentionPolicy;
		@@ -264,6 +265,13 @@ public final class IncrementalManager {
		return nativeIsIncrementalPath(path);
		}

		/**
		* Checks if an fd corresponds to a file on a mounted Incremental File System.
		*/
		public static boolean isIncrementalFileFd(@NonNull FileDescriptor fd) {
		return nativeIsIncrementalFd(fd.getInt$());
		}

		/**
		* Returns raw signature for file if it's on Incremental File System.
		* Unsafe, use only if you are sure what you are doing.
		@@ -437,5 +445,6 @@ public final class IncrementalManager {
		private static native boolean nativeIsEnabled();
		private static native boolean nativeIsV2Available();
		private static native boolean nativeIsIncrementalPath(@NonNull String path);
		private static native boolean nativeIsIncrementalFd(@NonNull int fd);
		private static native byte[] nativeUnsafeGetFileSignature(@NonNull String path);
		}

core/java/android/util/apk/ApkSigningBlockUtils.java

+2 −3

Original line number	Diff line number	Diff line
		@@ -200,10 +200,9 @@ public final class ApkSigningBlockUtils {
		// physical memory.

		DataSource beforeApkSigningBlock =
		new MemoryMappedFileDataSource(apkFileDescriptor, 0,
		signatureInfo.apkSigningBlockOffset);
		DataSource.create(apkFileDescriptor, 0, signatureInfo.apkSigningBlockOffset);
		DataSource centralDir =
		new MemoryMappedFileDataSource(
		DataSource.create(
		apkFileDescriptor, signatureInfo.centralDirOffset,
		signatureInfo.eocdOffset - signatureInfo.centralDirOffset);

core/java/android/util/apk/DataSource.java

+22 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,10 @@

		package android.util.apk;

		import android.annotation.NonNull;
		import android.os.incremental.IncrementalManager;

		import java.io.FileDescriptor;
		import java.io.IOException;
		import java.security.DigestException;

		@@ -35,4 +39,22 @@ interface DataSource {
		*/
		void feedIntoDataDigester(DataDigester md, long offset, int size)
		throws IOException, DigestException;

		/**
		* Creates a DataSource that can handle the passed fd in the most efficient and safe manner.
		* @param fd file descriptor to read from
		* @param pos starting offset
		* @param size size of the region
		* @return created DataSource object
		*/
		static @NonNull DataSource create(@NonNull FileDescriptor fd, long pos, long size) {
		if (IncrementalManager.isIncrementalFileFd(fd)) {
		// IncFS-based files may have missing pages, and reading those via mmap() results
		// in a SIGBUS signal. Java doesn't have a good way of catching it, ending up killing
		// the process by default. Going back to read() is the safest option for these files.
		return new ReadFileDataSource(fd, pos, size);
		} else {
		return new MemoryMappedFileDataSource(fd, pos, size);
		}
		}
		}

core/java/android/util/apk/MemoryMappedFileDataSource.java

+1 −0

Original line number	Diff line number	Diff line
		@@ -40,6 +40,7 @@ class MemoryMappedFileDataSource implements DataSource {
		/**
		* Constructs a new {@code MemoryMappedFileDataSource} for the specified region of the file.
		*
		* @param fd file descriptor to read from.
		* @param position start position of the region in the file.
		* @param size size (in bytes) of the region.
		*/

core/java/android/util/apk/ReadFileDataSource.java

0 → 100644

+73 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* 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 android.util.apk;

		import android.system.ErrnoException;
		import android.system.Os;

		import java.io.FileDescriptor;
		import java.io.IOException;
		import java.nio.ByteBuffer;
		import java.security.DigestException;

		/**
		* {@link DataSource} which provides data from a file descriptor by reading the sections
		* of the file via raw read() syscall. This is slower than memory-mapping but safer.
		*/
		class ReadFileDataSource implements DataSource {
		private final FileDescriptor mFd;
		private final long mFilePosition;
		private final long mSize;

		private static final int CHUNK_SIZE = 1024 * 1024;

		/**
		* Constructs a new {@code ReadFileDataSource} for the specified region of the file.
		*
		* @param fd file descriptor to read from.
		* @param position start position of the region in the file.
		* @param size size (in bytes) of the region.
		*/
		ReadFileDataSource(FileDescriptor fd, long position, long size) {
		mFd = fd;
		mFilePosition = position;
		mSize = size;
		}

		@Override
		public long size() {
		return mSize;
		}

		@Override
		public void feedIntoDataDigester(DataDigester md, long offset, int size)
		throws IOException, DigestException {
		try {
		final byte[] buffer = new byte[Math.min(size, CHUNK_SIZE)];
		final long start = mFilePosition + offset;
		final long end = start + size;
		for (long pos = start, curSize = Math.min(size, CHUNK_SIZE);
		pos < end; curSize = Math.min(end - pos, CHUNK_SIZE)) {
		final int readSize = Os.pread(mFd, buffer, 0, (int) curSize, pos);
		md.consume(ByteBuffer.wrap(buffer, 0, readSize));
		pos += readSize;
		}
		} catch (ErrnoException e) {
		throw new IOException(e);
		}
		}
		}