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問題：

項目中有一下情況：進程A調用另一進程的Ｂ ContentProvider,Ｂ在該此次query中需要在query另一個Ｃ ContentProvider:

    class BContentProvider extends ContentProvider {
        Context mContext;
        ...
        @Override
        public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
            ...
            try {
                // query C ContentProvider：
                Cursor cursor = mContext.getContentResolver().query(...);
                if (cursor != null) {
                    try {
                        //do something;
                    } finally {
                        cursor.close();
                    }
                }
                Cursor cursor = mContext.getContentResolver().query(...);
            ...
        ...
            }
        }
    }

在這種情況下，系統拋出Exception如下：

1-11 16:04:51.867  2633  3557 W AppOps  : Bad call: specified package com.providers.xxx under uid 10032 but it is really 10001
01-11 16:04:51.867  2633  3557 W AppOps  : java.lang.RuntimeException: here
01-11 16:04:51.867  2633  3557 W AppOps  :  at com.android.server.AppOpsService.getOpsRawLocked(AppOpsService.java:1399)
01-11 16:04:51.867  2633  3557 W AppOps  :  at com.android.server.AppOpsService.noteOperationUnchecked(AppOpsService.java:1115)
01-11 16:04:51.867  2633  3557 W AppOps  :  at com.android.server.AppOpsService.noteProxyOperation(AppOpsService.java:1093)
01-11 16:04:51.867  2633  3557 W AppOps  :  at com.android.internal.app.IAppOpsService$Stub.onTransact(IAppOpsService.java:157)
01-11 16:04:51.867  2633  3557 W AppOps  :  at android.os.BinderInjector.onTransact(BinderInjector.java:30)
01-11 16:04:51.867  2633  3557 W AppOps  :  at android.os.Binder.execTransact(Binder.java:569)
01-11 16:04:51.868  4659  6791 E DatabaseUtils: Writing exception to parcel
01-11 16:04:51.868  4659  6791 E DatabaseUtils: java.lang.SecurityException: Proxy package com.providers.xxx from uid 10001 or calling package com.providers.xxx from uid 10032 not allowed to perform READ_PROVIDER_C
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.app.AppOpsManager.noteProxyOp(AppOpsManager.java:1834)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProvider.checkPermissionAndAppOp(ContentProvider.java:538)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProvider.enforceReadPermissionInner(ContentProvider.java:560)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProvider$Transport.enforceReadPermission(ContentProvider.java:483)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProvider$Transport.query(ContentProvider.java:212)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentResolver.query(ContentResolver.java:532)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentResolver.query(ContentResolver.java:473)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at com.android.providers.xxx.BDatabaseHelper.query(BDatabaseHelper.java:7238)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at 
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProvider$Transport.query(ContentProvider.java:239)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:112)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.os.BinderInjector.onTransact(BinderInjector.java:30)
01-11 16:04:51.868  4659  6791 E DatabaseUtils:     at android.os.Binder.execTransact(Binder.java:569)

分析：

由于錯誤log首先反應了沒有C ContentProvider的權限，但檢查A應用是有C的讀寫權限的。所以排除了A的權限問題。
繼續分析：
通過log可以看到確實是ContentProvider在做權限檢查時出錯。通過log中對應的源碼進行分析：
首先可以看到ContentProvider.query()的時候做了權限檢查，注意，傳入的enforceReadPermission()的callingPkg是調用方的包名，以上面為例，就是B的包名。

ContentProvider.query():

        @Override
        public Cursor query(String callingPkg, Uri uri, @Nullable String[] projection,
                @Nullable Bundle queryArgs, @Nullable ICancellationSignal cancellationSignal) {
            validateIncomingUri(uri);
            uri = maybeGetUriWithoutUserId(uri);
            if (enforceReadPermission(callingPkg, uri, null) != AppOpsManager.MODE_ALLOWED) {

enforceReadPermission()調用了.checkPermissionAndAppOp()方法，ContentProvider.checkPermissionAndAppOp()調用了AppOpsManager.noteProxyOp()去做檢查出了異常。

AppOpsManager.noteProxyOp()：

    public int noteProxyOp(int op, String proxiedPackageName) {
        int mode = noteProxyOpNoThrow(op, proxiedPackageName);
        if (mode == MODE_ERRORED) {
            throw new SecurityException("Proxy package " + mContext.getOpPackageName()
                    + " from uid " + Process.myUid() + " or calling package "
                    + proxiedPackageName + " from uid " + Binder.getCallingUid()
                    + " not allowed to perform " + sOpNames[op]);
        }
        return mode;
    }

noteProxyOpNoThrow()又做了什么呢？
AppOpsManager.noteProxyOpNoThrow():

    /**
     * Like {@link #noteProxyOp(int, String)} but instead
     * of throwing a {@link SecurityException} it returns {@link #MODE_ERRORED}.
     * @hide
     */
    public int noteProxyOpNoThrow(int op, String proxiedPackageName) {
        try {
            return mService.noteProxyOperation(op, mContext.getOpPackageName(),
                    Binder.getCallingUid(), proxiedPackageName);
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }

可見noteProxyOpNoThrow()是通過binder調用到了AppOpsService.noteProxyOperation()方法，注意，這里傳入的是AppOpsService.noteProxyOperation()的后兩個參數為Binder.getCallingUid()和之前層層傳入的調用方的包名，也就是上面例子的B的包名。

下面，繼續看binder另一側的AppOpsService.noteProxyOperation()方法,我們結合log中AppOps的輸出log：

AppOpsService.noteProxyOperation():

    @Override
    public int noteProxyOperation(int code, String proxyPackageName,
            int proxiedUid, String proxiedPackageName) {
        verifyIncomingOp(code);
        final int proxyUid = Binder.getCallingUid();
        String resolveProxyPackageName = resolvePackageName(proxyUid, proxyPackageName);
        if (resolveProxyPackageName == null) {
            return AppOpsManager.MODE_IGNORED;
        }
        final int proxyMode = noteOperationUnchecked(code, proxyUid,
                resolveProxyPackageName, -1, null);
        if (proxyMode != AppOpsManager.MODE_ALLOWED || Binder.getCallingUid() == proxiedUid) {
            return proxyMode;
        }
        String resolveProxiedPackageName = resolvePackageName(proxiedUid, proxiedPackageName);
        if (resolveProxiedPackageName == null) {
            return AppOpsManager.MODE_IGNORED;
        }
        return noteOperationUnchecked(code, proxiedUid, resolveProxiedPackageName,
                proxyMode, resolveProxyPackageName);
    }

AppOpsService.noteOperationUnchecked():

   private int noteOperationUnchecked(int code, int uid, String packageName,
            int proxyUid, String proxyPackageName) {
        Op op = null;
        Op switchOp = null;
        int switchCode;
        int resultMode = AppOpsManager.MODE_ALLOWED;
        synchronized (this) {
            Ops ops = getOpsRawLocked(uid, packageName, true);
          ...
         }
    ...
}

AppOpsService.getOpsRawLocked():

    private Ops getOpsRawLocked(int uid, String packageName, boolean edit) {
        ...
        Ops ops = uidState.pkgOps.get(packageName);
        if (ops == null) {
            if (!edit) {
                return null;
            }
            boolean isPrivileged = false;
            // This is the first time we have seen this package name under this uid,
            // so let's make sure it is valid.
            if (uid != 0) {
                final long ident = Binder.clearCallingIdentity();
                try {
                    int pkgUid = -1;
                    try {
                        ApplicationInfo appInfo = ActivityThread.getPackageManager()
                                .getApplicationInfo(packageName,
                                        PackageManager.MATCH_DEBUG_TRIAGED_MISSING,
                                        UserHandle.getUserId(uid));
                        if (appInfo != null) {
                            pkgUid = appInfo.uid;
                            isPrivileged = (appInfo.privateFlags
                                    & ApplicationInfo.PRIVATE_FLAG_PRIVILEGED) != 0;
                        }
                        ...
                    }
                    ...
                    if (pkgUid != uid) {
                        // Oops!  The package name is not valid for the uid they are calling
                        // under.  Abort.
                        RuntimeException ex = new RuntimeException("here");
                        ex.fillInStackTrace();
                        Slog.w(TAG, "Bad call: specified package " + packageName
                                + " under uid " + uid + " but it is really " + pkgUid, ex);
                        return null;
                    }
                } finally {
                    Binder.restoreCallingIdentity(ident);
                }
            }
            ops = new Ops(packageName, uidState, isPrivileged);
            uidState.pkgOps.put(packageName, ops);
        }
        return ops;
    }

這里主要的操作就是將傳入的uid和包名進行判斷：比對該包對應的uid和傳入的uid比較，如果不一致就報錯。錯誤信息和log中的一致：

Bad call: specified package com.providers.xxx under uid 10032 but it is really 10001

上文提到了，這個包名是傳入的ContentProvider的調用方的包名，也就是例子中的B的包名。而uid是在AppOpsManager中通過Binder.getCallingUid()獲得的。log中顯示，此uid并不是B的uid，而是其上游調用者A的uid。
為什么在C中調用Binder.getCallingUid()得到的是A進程的呢？我找到了袁輝輝大神的一片博客： Binder IPC的權限控制

“線程B通過Binder調用當前線程的某個組件：此時線程B是線程B某個組件的調用端，則mCallingUid和mCallingPid應該保存當前線程B的PID和UID，故需要調用clearCallingIdentity()方法完成這個功能。當線程B調用完某個組件，由于線程B仍然處于線程A的被調用端，因此mCallingUid和mCallingPid需要恢復成線程A的UID和PID，這是調用restoreCallingIdentity()即可完成。”

Binder的機制就是這么設計的，所以需要在B進行下一次Binder調用(也就是query ContentProvider)之前調用clearCallingIdentity()來將B的
PID和UID附給mCallingUid和mCallingPid。Binder調用結束后在restoreCallingIdentity()來將其恢復成其原本調用方的PID和UID。這樣在C里就會用B的相關信息進行權限校驗，在AppOpsService.getOpsRawLocked()，UID和包名都是B的，是一致的，就不會報錯。

解決辦法：

其實上文也已經提到了，參考 Binder IPC的權限控制，在B進行Query前后分別調用clearCallingIdentity()
//作用是清空遠程調用端的uid和pid，用當前本地進程的uid和pid替代，這樣在之后的調用方去進行權限校驗時會以B的信息為主，不會出現包名和UID不一致的情況。
最后修改過的調用方式如下：

        long token = Binder.clearCallingIdentity();
        try {
            Cursor cursor = mContext.getContentResolver().query(...);
            if (cursor != null) {
                try {
                    //do something;
                } finally {
                    cursor.close();
                }
            }
        } finally {
            Binder.restoreCallingIdentity(token);
        }

總結：

1.ContentProvider是用Binder實現的，查詢的過程其實就是一次Binder調用，所以想深入了解ContentProvider一定要會一些Binder相關的知識。
2.ContentProvider在接受一次查詢前會調用AppOpsManager(其會通過Binder再由AppOpsService完成)進行權限校驗，其中會校驗調用方的UID和包名是否一致，其相關功能可見文章： Android 權限管理 —— AppOps。
2.Binder調用時候可以通過Binder.getCallingPid()和Binder.getCallingUid()來獲取調用方的PID和UID，而如果A通過Binder調用B，B又Binder調用了C，那么在C中Binder.getCallingPid()和Binder.getCallingUid()得到的是A的PID和UID，這種情況下需要在B調用C的前后用Binder.clearCallingIdentity()和Binder.restoreCallingIdentity()使其帶上B的PID和UID，從而在C中進行權限校驗時候用B的信息進行校驗，當然這也符合邏輯，B調用的C，應該B需要有相應權限。
3.Binder.clearCallingIdentity()和Binder.restoreCallingIdentity()的實現原理 Binder IPC的權限控制也有介紹，是通過移位實現的。

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Android ContentProvider調用報錯"Bad call: specified package xxx under uid 10032 but it is really 10001"及Binder權限問題分析

Android ContentProvider調用報錯"Bad call: specified package xxx under uid 10032 but it is really 10001"及Binder權限問題分析

問題：

分析：

解決辦法：

總結：

三个男躁一个女,国精产品一区一手机的秘密,麦子交换系列最经典十句话,欧美 国产 综合 欧美 视频

Android ContentProvider調用報錯"Bad call: specified package xxx under uid 10032 but it is really 10001"及Binder權限問題分析

問題：

分析：

解決辦法：

總結：

三个男躁一个女,国精产品一区一手机的秘密,麦子交换系列最经典十句话,欧美国产综合欧美视频