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Commit a573f6a1 authored by Dianne Hackborn's avatar Dianne Hackborn
Browse files

Some hardening of isolated processes by restricting access to services. 

Services now must explicitly opt in to being accessed by isolated
processes.  Currently only the activity manager and surface flinger
allow this.  Activity manager is needed so that we can actually
bring up the process; SurfaceFlinger is needed to be able to get the
display information for creating the Configuration.  The SurfaceFlinger
should be safe because the app doesn't have access to the window
manager so can't actually get a surface to do anything with.

The activity manager now protects most of its entry points against
isolated processes.

Change-Id: I0dad8cb2c873575c4c7659c3c2a7eda8e98f46b0
parent 7ff3144a

cmds/servicemanager/service_manager.c

+18 −5
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ struct svcinfo 
    struct svcinfo *next;

    void *ptr;

    struct binder_death death;

    int allow_isolated;

    unsigned len;

    uint16_t name[0];

};
@@ -125,13 +126,21 @@ uint16_t svcmgr_id[] = { 
};

  



void *do_find_service(struct binder_state *bs, uint16_t *s, unsigned len)

void *do_find_service(struct binder_state *bs, uint16_t *s, unsigned len, unsigned uid)

{

    struct svcinfo *si;

    si = find_svc(s, len);



//    ALOGI("check_service('%s') ptr = %p\n", str8(s), si ? si->ptr : 0);

    if (si && si->ptr) {

        if (!si->allow_isolated) {

            // If this service doesn't allow access from isolated processes,

            // then check the uid to see if it is isolated.

            unsigned appid = uid % AID_USER;

            if (appid >= AID_ISOLATED_START && appid <= AID_ISOLATED_END) {

                return 0;

            }

        }

        return si->ptr;

    } else {

        return 0;
@@ -140,10 +149,11 @@ void *do_find_service(struct binder_state *bs, uint16_t *s, unsigned len) 


int do_add_service(struct binder_state *bs,

                   uint16_t *s, unsigned len,

                   void *ptr, unsigned uid)

                   void *ptr, unsigned uid, int allow_isolated)

{

    struct svcinfo *si;

//    ALOGI("add_service('%s',%p) uid=%d\n", str8(s), ptr, uid);

    //ALOGI("add_service('%s',%p,%s) uid=%d\n", str8(s), ptr,

    //        allow_isolated ? "allow_isolated" : "!allow_isolated", uid);



    if (!ptr || (len == 0) || (len > 127))

        return -1;
@@ -175,6 +185,7 @@ int do_add_service(struct binder_state *bs, 
        si->name[len] = '\0';

        si->death.func = svcinfo_death;

        si->death.ptr = si;

        si->allow_isolated = allow_isolated;

        si->next = svclist;

        svclist = si;

    }
@@ -194,6 +205,7 @@ int svcmgr_handler(struct binder_state *bs, 
    unsigned len;

    void *ptr;

    uint32_t strict_policy;

    int allow_isolated;



//    ALOGI("target=%p code=%d pid=%d uid=%d\n",

//         txn->target, txn->code, txn->sender_pid, txn->sender_euid);
@@ -217,7 +229,7 @@ int svcmgr_handler(struct binder_state *bs, 
    case SVC_MGR_GET_SERVICE:

    case SVC_MGR_CHECK_SERVICE:

        s = bio_get_string16(msg, &len);

        ptr = do_find_service(bs, s, len);

        ptr = do_find_service(bs, s, len, txn->sender_euid);

        if (!ptr)

            break;

        bio_put_ref(reply, ptr);
@@ -226,7 +238,8 @@ int svcmgr_handler(struct binder_state *bs, 
    case SVC_MGR_ADD_SERVICE:

        s = bio_get_string16(msg, &len);

        ptr = bio_get_ref(msg);

        if (do_add_service(bs, s, len, ptr, txn->sender_euid))

        allow_isolated = bio_get_uint32(msg) ? 1 : 0;

        if (do_add_service(bs, s, len, ptr, txn->sender_euid, allow_isolated))

            return -1;

        break;

cmds/surfaceflinger/main_surfaceflinger.cpp

+1 −1
Original line number Diff line number Diff line
@@ -20,6 +20,6 @@ 
using namespace android;



int main(int argc, char** argv) {

    SurfaceFlinger::publishAndJoinThreadPool();

    SurfaceFlinger::publishAndJoinThreadPool(true);

    return 0;

}

core/java/android/os/IServiceManager.java

+2 −1
Original line number Diff line number Diff line
@@ -45,7 +45,8 @@ public interface IServiceManager extends IInterface 
     * Place a new @a service called @a name into the service

     * manager.

     */

    public void addService(String name, IBinder service) throws RemoteException;

    public void addService(String name, IBinder service, boolean allowIsolated)

                throws RemoteException;



    /**

     * Return a list of all currently running services.

core/java/android/os/ServiceManager.java

+18 −1
Original line number Diff line number Diff line
@@ -69,7 +69,24 @@ public final class ServiceManager { 
     */

    public static void addService(String name, IBinder service) {

        try {

            getIServiceManager().addService(name, service);

            getIServiceManager().addService(name, service, false);

        } catch (RemoteException e) {

            Log.e(TAG, "error in addService", e);

        }

    }



    /**

     * Place a new @a service called @a name into the service

     * manager.

     * 

     * @param name the name of the new service

     * @param service the service object

     * @param allowIsolated set to true to allow isolated sandboxed processes

     * to access this service

     */

    public static void addService(String name, IBinder service, boolean allowIsolated) {

        try {

            getIServiceManager().addService(name, service, allowIsolated);

        } catch (RemoteException e) {

            Log.e(TAG, "error in addService", e);

        }

core/java/android/os/ServiceManagerNative.java

+4 −2
Original line number Diff line number Diff line
@@ -71,7 +71,8 @@ public abstract class ServiceManagerNative extends Binder implements IServiceMan 
                data.enforceInterface(IServiceManager.descriptor);

                String name = data.readString();

                IBinder service = data.readStrongBinder();

                addService(name, service);

                boolean allowIsolated = data.readInt() != 0;

                addService(name, service, allowIsolated);

                return true;

            }
@@ -136,13 +137,14 @@ class ServiceManagerProxy implements IServiceManager { 
        return binder;

    }



    public void addService(String name, IBinder service)

    public void addService(String name, IBinder service, boolean allowIsolated)

            throws RemoteException {

        Parcel data = Parcel.obtain();

        Parcel reply = Parcel.obtain();

        data.writeInterfaceToken(IServiceManager.descriptor);

        data.writeString(name);

        data.writeStrongBinder(service);

        data.writeInt(allowIsolated ? 1 : 0);

        mRemote.transact(ADD_SERVICE_TRANSACTION, data, reply, 0);

        reply.recycle();

        data.recycle();