src/com/android/nfc/NfceeAccessControl.java - platform/packages/apps/Nfc - Git at Google

 /*
  * Copyright (C) 2011 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 com.android.nfc;

 import java.io.File;
 import java.io.FileDescriptor;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.HashMap;

 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 import org.xmlpull.v1.XmlPullParserFactory;

 import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.Signature;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.Environment;
 import android.util.Log;

 public class NfceeAccessControl {
     static final String TAG = "NfceeAccess";
     static final boolean DBG = true;

     public static final String NFCEE_ACCESS_PATH = "/etc/nfcee_access.xml";

     /**
      * Map of signatures to valid packages names, as read from nfcee_access.xml.
      * An empty list of package names indicates that any package
      * with this signature is allowed.
      */
     final HashMap<Signature, String[]> mNfceeAccess;  // contents final after onCreate()

     /**
      * Map from UID to NFCEE access, used as a cache.
      * Note: if a UID contains multiple packages they must all be
      * signed with the same certificate so in effect UID == certificate
      * used to sign the package.
      */
     final HashMap<Integer, Boolean> mUidCache;  // contents guarded by this

     final Context mContext;
     final boolean mDebugPrintSignature;

     NfceeAccessControl(Context context) {
         mContext = context;
         mNfceeAccess = new HashMap<Signature, String[]>();
         mUidCache = new HashMap<Integer, Boolean>();
         mDebugPrintSignature = parseNfceeAccess();
     }

     /**
      * Check if the {uid, pkg} combination may use NFCEE.
      * Also verify with package manager that this {uid, pkg} combination
      * is valid if it is not cached.
      */
     public boolean check(int uid, String pkg) {
         synchronized (this) {
             Boolean cached = mUidCache.get(uid);
             if (cached != null) {
                 return cached;
             }

             boolean access = false;

             // Ensure the claimed package is present in the calling UID
             PackageManager pm = mContext.getPackageManager();
             String[] pkgs = pm.getPackagesForUid(uid);
             for (String uidPkg : pkgs) {
                 if (uidPkg.equals(pkg)) {
                     // Ensure the package has access permissions
                     if (checkPackageNfceeAccess(pkg)) {
                         access = true;
                     }
                     break;
                 }
             }

             mUidCache.put(uid, access);
             return access;
         }
     }

     /**
      * Check if the given ApplicationInfo may use the NFCEE.
      * Assumes ApplicationInfo came from package manager,
      * so no need to confirm {uid, pkg} is valid.
      */
     public boolean check(ApplicationInfo info) {
         synchronized (this) {
             Boolean access = mUidCache.get(info.uid);
             if (access == null) {
                 access = checkPackageNfceeAccess(info.packageName);
                 mUidCache.put(info.uid, access);
             }
             return access;
         }
     }

     public void invalidateCache() {
         synchronized (this) {
             mUidCache.clear();
         }
     }

     /**
      * Check with package manager if the pkg may use NFCEE.
      * Does not use cache.
      */
     boolean checkPackageNfceeAccess(String pkg) {
         PackageManager pm = mContext.getPackageManager();
         try {
             PackageInfo info = pm.getPackageInfo(pkg, PackageManager.GET_SIGNATURES);
             if (info.signatures == null) {
                 return false;
             }

             for (Signature s : info.signatures){
                 if (s == null) {
                     continue;
                 }
                 String[] packages = mNfceeAccess.get(s);
                 if (packages == null) {
                     continue;
                 }
                 if (packages.length == 0) {
                     // wildcard access
                     if (DBG) Log.d(TAG, "Granted NFCEE access to " + pkg + " (wildcard)");
                     return true;
                 }
                 for (String p : packages) {
                     if (pkg.equals(p)) {
                         // explicit package access
                         if (DBG) Log.d(TAG, "Granted access to " + pkg + " (explicit)");
                         return true;
                     }
                 }
             }

             if (mDebugPrintSignature) {
                 Log.w(TAG, "denied NFCEE access for " + pkg + " with signature:");
                 for (Signature s : info.signatures) {
                     if (s != null) {
                         Log.w(TAG, s.toCharsString());
                     }
                 }
             }
         } catch (NameNotFoundException e) {
             // ignore
         }
         return false;
     }

     /**
      * Parse nfcee_access.xml, populate mNfceeAccess
      * Policy is to ignore unexpected XML elements and continue processing,
      * except for obvious errors within a <signer> group since they might cause
      * package names to by ignored and therefore wildcard access granted
      * by mistake. Those errors invalidate the entire <signer> group.
      */
     boolean parseNfceeAccess() {
         File file = new File(Environment.getRootDirectory(), NFCEE_ACCESS_PATH);
         FileReader reader = null;
         boolean debug = false;
         try {
             reader = new FileReader(file);
             XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
             XmlPullParser parser = factory.newPullParser();
             parser.setInput(reader);

             int event;
             ArrayList<String> packages = new ArrayList<String>();
             Signature signature = null;
             parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
             while (true) {
                 event = parser.next();
                 String tag = parser.getName();
                 if (event == XmlPullParser.START_TAG && "signer".equals(tag)) {
                     signature = null;
                     packages.clear();
                     for (int i = 0; i < parser.getAttributeCount(); i++) {
                         if ("android:signature".equals(parser.getAttributeName(i))) {
                             signature = new Signature(parser.getAttributeValue(i));
                             break;
                         }
                     }
                     if (signature == null) {
                         Log.w(TAG, "signer tag is missing android:signature attribute, igorning");
                         continue;
                     }
                     if (mNfceeAccess.containsKey(signature)) {
                         Log.w(TAG, "duplicate signature, ignoring");
                         signature = null;
                         continue;
                     }
                 } else if (event == XmlPullParser.END_TAG && "signer".equals(tag)) {
                     if (signature == null) {
                         Log.w(TAG, "mis-matched signer tag");
                         continue;
                     }
                     mNfceeAccess.put(signature, packages.toArray(new String[0]));
                     packages.clear();
                 } else if (event == XmlPullParser.START_TAG && "package".equals(tag)) {
                     if (signature == null) {
                         Log.w(TAG, "ignoring unnested packge tag");
                         continue;
                     }
                     String name = null;
                     for (int i = 0; i < parser.getAttributeCount(); i++) {
                         if ("android:name".equals(parser.getAttributeName(i))) {
                             name = parser.getAttributeValue(i);
                             break;
                         }
                     }
                     if (name == null) {
                         Log.w(TAG, "package missing android:name, ignoring signer group");
                         signature = null;  // invalidate signer
                         continue;
                     }
                     // check for duplicate package names
                     if (packages.contains(name)) {
                         Log.w(TAG, "duplicate package name in signer group, ignoring");
                         continue;
                     }
                     packages.add(name);
                 } else if (event == XmlPullParser.START_TAG && "debug".equals(tag)) {
                     debug = true;
                 } else if (event == XmlPullParser.END_DOCUMENT) {
                     break;
                 }
             }
         } catch (XmlPullParserException e) {
             Log.w(TAG, "failed to load NFCEE access list", e);
             mNfceeAccess.clear();  // invalidate entire access list
         } catch (FileNotFoundException e) {
             Log.w(TAG, "could not find " + NFCEE_ACCESS_PATH + ", no NFCEE access allowed");
         } catch (IOException e) {
             Log.e(TAG, "Failed to load NFCEE access list", e);
             mNfceeAccess.clear();  // invalidate entire access list
         } finally {
             if (reader != null) {
                 try {
                     reader.close();
                 } catch (IOException e2)  { }
             }
         }
         Log.i(TAG, "read " + mNfceeAccess.size() + " signature(s) for NFCEE access");
         return debug;
     }

     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
         pw.println("mNfceeAccess=");
         for (Signature s : mNfceeAccess.keySet()) {
             pw.printf("\t%s [", s.toCharsString());
             String[] ps = mNfceeAccess.get(s);
             for (String p : ps) {
                 pw.printf("%s, ", p);
             }
             pw.println("]");
         }
         synchronized (this) {
             pw.println("mNfceeUidCache=");
             for (Integer uid : mUidCache.keySet()) {
                 Boolean b = mUidCache.get(uid);
                 pw.printf("\t%d %s\n", uid, b);
             }
         }
     }
 }
	/*
	* Copyright (C) 2011 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 com.android.nfc;

	import java.io.File;
	import java.io.FileDescriptor;
	import java.io.FileNotFoundException;
	import java.io.FileReader;
	import java.io.IOException;
	import java.io.PrintWriter;
	import java.util.ArrayList;
	import java.util.HashMap;

	import org.xmlpull.v1.XmlPullParser;
	import org.xmlpull.v1.XmlPullParserException;
	import org.xmlpull.v1.XmlPullParserFactory;

	import android.content.Context;
	import android.content.pm.ApplicationInfo;
	import android.content.pm.PackageInfo;
	import android.content.pm.PackageManager;
	import android.content.pm.Signature;
	import android.content.pm.PackageManager.NameNotFoundException;
	import android.os.Environment;
	import android.util.Log;

	public class NfceeAccessControl {
	static final String TAG = "NfceeAccess";
	static final boolean DBG = true;

	public static final String NFCEE_ACCESS_PATH = "/etc/nfcee_access.xml";

	/**
	* Map of signatures to valid packages names, as read from nfcee_access.xml.
	* An empty list of package names indicates that any package
	* with this signature is allowed.
	*/
	final HashMap<Signature, String[]> mNfceeAccess; // contents final after onCreate()

	/**
	* Map from UID to NFCEE access, used as a cache.
	* Note: if a UID contains multiple packages they must all be
	* signed with the same certificate so in effect UID == certificate
	* used to sign the package.
	*/
	final HashMap<Integer, Boolean> mUidCache; // contents guarded by this

	final Context mContext;
	final boolean mDebugPrintSignature;

	NfceeAccessControl(Context context) {
	mContext = context;
	mNfceeAccess = new HashMap<Signature, String[]>();
	mUidCache = new HashMap<Integer, Boolean>();
	mDebugPrintSignature = parseNfceeAccess();
	}

	/**
	* Check if the {uid, pkg} combination may use NFCEE.
	* Also verify with package manager that this {uid, pkg} combination
	* is valid if it is not cached.
	*/
	public boolean check(int uid, String pkg) {
	synchronized (this) {
	Boolean cached = mUidCache.get(uid);
	if (cached != null) {
	return cached;
	}

	boolean access = false;

	// Ensure the claimed package is present in the calling UID
	PackageManager pm = mContext.getPackageManager();
	String[] pkgs = pm.getPackagesForUid(uid);
	for (String uidPkg : pkgs) {
	if (uidPkg.equals(pkg)) {
	// Ensure the package has access permissions
	if (checkPackageNfceeAccess(pkg)) {
	access = true;
	}
	break;
	}
	}

	mUidCache.put(uid, access);
	return access;
	}
	}

	/**
	* Check if the given ApplicationInfo may use the NFCEE.
	* Assumes ApplicationInfo came from package manager,
	* so no need to confirm {uid, pkg} is valid.
	*/
	public boolean check(ApplicationInfo info) {
	synchronized (this) {
	Boolean access = mUidCache.get(info.uid);
	if (access == null) {
	access = checkPackageNfceeAccess(info.packageName);
	mUidCache.put(info.uid, access);
	}
	return access;
	}
	}

	public void invalidateCache() {
	synchronized (this) {
	mUidCache.clear();
	}
	}

	/**
	* Check with package manager if the pkg may use NFCEE.
	* Does not use cache.
	*/
	boolean checkPackageNfceeAccess(String pkg) {
	PackageManager pm = mContext.getPackageManager();
	try {
	PackageInfo info = pm.getPackageInfo(pkg, PackageManager.GET_SIGNATURES);
	if (info.signatures == null) {
	return false;
	}

	for (Signature s : info.signatures){
	if (s == null) {
	continue;
	}
	String[] packages = mNfceeAccess.get(s);
	if (packages == null) {
	continue;
	}
	if (packages.length == 0) {
	// wildcard access
	if (DBG) Log.d(TAG, "Granted NFCEE access to " + pkg + " (wildcard)");
	return true;
	}
	for (String p : packages) {
	if (pkg.equals(p)) {
	// explicit package access
	if (DBG) Log.d(TAG, "Granted access to " + pkg + " (explicit)");
	return true;
	}
	}
	}

	if (mDebugPrintSignature) {
	Log.w(TAG, "denied NFCEE access for " + pkg + " with signature:");
	for (Signature s : info.signatures) {
	if (s != null) {
	Log.w(TAG, s.toCharsString());
	}
	}
	}
	} catch (NameNotFoundException e) {
	// ignore
	}
	return false;
	}

	/**
	* Parse nfcee_access.xml, populate mNfceeAccess
	* Policy is to ignore unexpected XML elements and continue processing,
	* except for obvious errors within a <signer> group since they might cause
	* package names to by ignored and therefore wildcard access granted
	* by mistake. Those errors invalidate the entire <signer> group.
	*/
	boolean parseNfceeAccess() {
	File file = new File(Environment.getRootDirectory(), NFCEE_ACCESS_PATH);
	FileReader reader = null;
	boolean debug = false;
	try {
	reader = new FileReader(file);
	XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
	XmlPullParser parser = factory.newPullParser();
	parser.setInput(reader);

	int event;
	ArrayList<String> packages = new ArrayList<String>();
	Signature signature = null;
	parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
	while (true) {
	event = parser.next();
	String tag = parser.getName();
	if (event == XmlPullParser.START_TAG && "signer".equals(tag)) {
	signature = null;
	packages.clear();
	for (int i = 0; i < parser.getAttributeCount(); i++) {
	if ("android:signature".equals(parser.getAttributeName(i))) {
	signature = new Signature(parser.getAttributeValue(i));
	break;
	}
	}
	if (signature == null) {
	Log.w(TAG, "signer tag is missing android:signature attribute, igorning");
	continue;
	}
	if (mNfceeAccess.containsKey(signature)) {
	Log.w(TAG, "duplicate signature, ignoring");
	signature = null;
	continue;
	}
	} else if (event == XmlPullParser.END_TAG && "signer".equals(tag)) {
	if (signature == null) {
	Log.w(TAG, "mis-matched signer tag");
	continue;
	}
	mNfceeAccess.put(signature, packages.toArray(new String[0]));
	packages.clear();
	} else if (event == XmlPullParser.START_TAG && "package".equals(tag)) {
	if (signature == null) {
	Log.w(TAG, "ignoring unnested packge tag");
	continue;
	}
	String name = null;
	for (int i = 0; i < parser.getAttributeCount(); i++) {
	if ("android:name".equals(parser.getAttributeName(i))) {
	name = parser.getAttributeValue(i);
	break;
	}
	}
	if (name == null) {
	Log.w(TAG, "package missing android:name, ignoring signer group");
	signature = null; // invalidate signer
	continue;
	}
	// check for duplicate package names
	if (packages.contains(name)) {
	Log.w(TAG, "duplicate package name in signer group, ignoring");
	continue;
	}
	packages.add(name);
	} else if (event == XmlPullParser.START_TAG && "debug".equals(tag)) {
	debug = true;
	} else if (event == XmlPullParser.END_DOCUMENT) {
	break;
	}
	}
	} catch (XmlPullParserException e) {
	Log.w(TAG, "failed to load NFCEE access list", e);
	mNfceeAccess.clear(); // invalidate entire access list
	} catch (FileNotFoundException e) {
	Log.w(TAG, "could not find " + NFCEE_ACCESS_PATH + ", no NFCEE access allowed");
	} catch (IOException e) {
	Log.e(TAG, "Failed to load NFCEE access list", e);
	mNfceeAccess.clear(); // invalidate entire access list
	} finally {
	if (reader != null) {
	try {
	reader.close();
	} catch (IOException e2) { }
	}
	}
	Log.i(TAG, "read " + mNfceeAccess.size() + " signature(s) for NFCEE access");
	return debug;
	}

	public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
	pw.println("mNfceeAccess=");
	for (Signature s : mNfceeAccess.keySet()) {
	pw.printf("\t%s [", s.toCharsString());
	String[] ps = mNfceeAccess.get(s);
	for (String p : ps) {
	pw.printf("%s, ", p);
	}
	pw.println("]");
	}
	synchronized (this) {
	pw.println("mNfceeUidCache=");
	for (Integer uid : mUidCache.keySet()) {
	Boolean b = mUidCache.get(uid);
	pw.printf("\t%d %s\n", uid, b);
	}
	}
	}
	}