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Stronger constraints around install session IDs.

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Generate positive, non-zero session IDs, and don't recycle them
within a given boot.  Guard against ID starvation by crazy apps.

Bug: 16792837
Change-Id: I6035afe4d942d358b5ca12b4f818c55885b74aba
This commit is contained in:
Jeff Sharkey
2014-08-05 10:42:27 -07:00
committed by Jeff Sharkey
parent 966e258396
commit f174c6e6de
2 changed files with 21 additions and 7 deletions
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3
core/java/android/content/pm/PackageInstaller.java
View File

@@ -114,6 +114,9 @@ public class PackageInstaller {
*
* @throws IOException if parameters were unsatisfiable, such as lack of
* disk space or unavailable media.
* @return positive, non-zero unique ID that represents the created session.
* This ID remains consistent across device reboots until the
* session is finalized. IDs are not reused during a given boot.
*/
public int createSession(@NonNull InstallSessionParams params) throws IOException {
try {

25
services/core/java/com/android/server/pm/PackageInstallerService.java
View File

@@ -121,8 +121,12 @@ public class PackageInstallerService extends IPackageInstaller.Stub {
private static final String ATTR_REFERRER_URI = "referrerUri";
private static final String ATTR_ABI_OVERRIDE = "abiOverride";
/** Automatically destroy sessions older than this */
private static final long MAX_AGE_MILLIS = 3 * DateUtils.DAY_IN_MILLIS;
/** Upper bound on number of active sessions for a UID */
private static final long MAX_ACTIVE_SESSIONS = 1024;
/** Upper bound on number of historical sessions for a UID */
private static final long MAX_HISTORICAL_SESSIONS = 1048576;
private final Context mContext;
private final PackageManagerService mPm;
@@ -410,9 +414,15 @@ public class PackageInstallerService extends IPackageInstaller.Stub {
final PackageInstallerSession session;
synchronized (mSessions) {
// Sanity check that installer isn't going crazy
final int activeCount = getSessionCountLocked(callingUid);
final int activeCount = getSessionCount(mSessions, callingUid);
if (activeCount >= MAX_ACTIVE_SESSIONS) {
throw new IllegalStateException("Too many active sessions for UID " + callingUid);
throw new IllegalStateException(
"Too many active sessions for UID " + callingUid);
}
final int historicalCount = getSessionCount(mHistoricalSessions, callingUid);
if (historicalCount >= MAX_HISTORICAL_SESSIONS) {
throw new IllegalStateException(
"Too many historical sessions for UID " + callingUid);
}
sessionId = allocateSessionIdLocked();
@@ -452,8 +462,8 @@ public class PackageInstallerService extends IPackageInstaller.Stub {
int n = 0;
int sessionId;
do {
sessionId = mRandom.nextInt(Integer.MAX_VALUE);
if (mSessions.get(sessionId) == null) {
sessionId = mRandom.nextInt(Integer.MAX_VALUE - 1) + 1;
if (mSessions.get(sessionId) == null && mHistoricalSessions.get(sessionId) == null) {
return sessionId;
}
} while (n++ < 32);
@@ -560,11 +570,12 @@ public class PackageInstallerService extends IPackageInstaller.Stub {
mCallbacks.unregister(callback);
}
private int getSessionCountLocked(int installerUid) {
private static int getSessionCount(SparseArray<PackageInstallerSession> sessions,
int installerUid) {
int count = 0;
final int size = mSessions.size();
final int size = sessions.size();
for (int i = 0; i < size; i++) {
final PackageInstallerSession session = mSessions.valueAt(i);
final PackageInstallerSession session = sessions.valueAt(i);
if (session.installerUid == installerUid) {
count++;
}