Today, I received an email which states,
[Firebase] Your Realtime Database 'CC-default-rtdb' has insecure rules, any user can read your entire database, any user can write to your entire database
My server runs every day to store values in the Realtime Database. When I started this Firebase project, I used the basic read and write rules.
{
"rules": {
".read": true,
".write": true
}
}
If I change the rules now, does it affect my external Node.JS server from storing values into the Realtime DB?
I even access this DB from a mobile app, so will it affect the mobile app from reading data if the rules are changed?
How can I secure these Realtime DB rules (from public to private) without interrupting the access for the external server and mobile app? Importantly, my external server access must not get disrupted.
If you are accessing your database through authentication(login) you can set your nodes to auth!=null so that any unauthorized user cannot access them.
You need to follow the following steps:
Set read to true for all nodes you need to make publicly available
Set read/write to auth!=null for all nodes you want to make available to any authorized user
Set custom validation rules for any node that needs special access (e.g.: A user can only write to his/her data)
As per the screenshot, if anyone gets a hold of your project id, they can modify and steal your entire database.
You need to set rules in a way that properly matches your use case. As far as I understand:
Allow the external server account access to the whole DB
Allow the mobile app conditional access (by user perhaps?)
Example
Take this database for instance:
{
"top_level": {
"users": [
{
"username": "X",
"userId": "0"
},
{
"username": "Y",
"userId": "1"
}
],
"public_data": {
"news": [
{
"title": "X",
"body": "Y"
}
]
}
}
}
I want to set:
Node "news" to be publicly available to read (no auth)
Node "users" to be only available to other logged-in users to read(auth)
Children of node "users" to only be writable for the user whose id matches the value userId in the node
The rule, in this case, would be:
{
"rules": {
".read": false,
".write": false,
"top_level": {
"users": {
".read": "auth!=null",
"$user_id": {
".write": "auth!=null && data.child('userId').val()===auth.uid"
}
},
"news" : {
".read":true
}
}
}
}
Note, rules set as true in the top-level override inner rules.
Comment if you need clarification.
Related
I'm working on a contact-app for android with firebase and I want to read values (here: the users' profile) from a user in my database that matches a specified email.
I tried to design the query like shown in this answer: https://stackoverflow.com/a/39025129/8739722 but the problem is that I don't know how to apply this to my database-structure since I have another child (profile) in my user-structure.
My Nodes look like this:
My Rules look like this:
{
"rules": {
"users": {
"$uid": {
"profile": {
".read": "auth.uid != null",
".write": "auth.uid == $uid",
},
//...
},
}
I tried to query like this:
String email = "email_address_1";
Query q_1 = ref.child("users").child("profile").orderByChild("email").equalTo(email);
...resulting in a 'permission denied' error.
I also considered following queries but they have invalid syntax or try to perform multiple orderByChild-calls which is not allowed:
String email = "email_address_1";
Query q_2 = ref.child("users").orderByChild("profile").child("email").equalTo(email);
Query q_3 = ref.child("users").orderByChild("profile").orderByChild("email").equalTo(email);
How can I get the profile-information of the user with the matching email?
Firebase Realtime Database queries filter and order on a single property that is under a fixed path/name under each child node of the location where you run the query. In your case the property is under profile/email, so your query becomes:
ref.child("users").orderByChild("profile/email").equalTo(email);
But note that your rules will reject this query, since they request to read data from /users and you don't grant anyone permission to read data from there. Firebase security rules are enforced when you attach a listener, and can't be used to filter data. To learn a lot more about this, read the documentation section called rules are not filters and the many questions mentioning that same phrase.
To quickly test the above query, you can temporarily grant every access to /users. Just be sure to change it back before sharing your app with any users.
To properly secure the data you'll need to verify in your security rules that the user is only trying to read their own data. You can do this with query based security rules. In your case they'd look something like this:
"users": {
".read": "auth.email != null &&
query.orderByChild == 'profile/email' &&
query.equalTo == auth.token.email"
}
I have a realtime database structure like below.
Users have some friends. For example, I am Joe and I'd like to fetch users who have friends as Joe.
In this example, Dave and Harry have a friend called Joe, so my query should fetch Dave and Harry but shouldn't Micheal.
Is there a way to do this without fetching data in a loop?
{
"Users": {
"Joe": {
"Friends": ["Dave","Harry","Micheal"]
},
"Dave": {
"Friends": ["Joe","Jack","Brent"]
},
"Harry": {
"Friends": ["Jack","Joe"]
},
"Micheal": {
"Friends": ["Ken","Jack","Brent"]
}
}
}
Firebase Realtime database cannot perform a query across array members, to see if it contains a specific value in any position or to add/remove a record. Firebase documentation recommends against using arrays. One of the many reasons Firebase recommends against using arrays is that it makes the security rules impossible to write.
As usual with NoSQL databases: if you can't perform the use-case you want with your current data structure, you can typically change/expand your data structure to allow the use-case. The best practice is to use maps instead of arrays. A possible database structure could look like this:
"Users": {
"Joe": {
"Friends"
"Dave": true,
"Harry": true,
"Micheal": true
},
"Dave": {
"Friends"
"Joe": true,
"Jack":true,
"Brent": true
},
"Harry": {
"Friends"
"Jack": true,
"Joe": true
},
"Micheal": {
"Friends"
"Ken":true,
"Jack": true,
"Brent": true
}
}
You can also take a look, here, for more informations.
Recently found out the database rules can be set to validate whether the database already have the same data but currently it just accepted same data to insert but how to validate and prevent same input of username and email?
{
"rules": {
".read": true,
".write": true,
"username":{
".validate": "!root.child('username').child(newData.val()).exists()"
},
"email":{
".validate": "!root.child('email').child(newData.val()).exists()"
}
}
}
The root child is created by email authentication uid and the rest will be under the same nodes.
How to prevent user enter same username and email?
Your rules validate if a single property /username exists and has the same value as the new data you're writing. Your use-case seems different: you want to ensure a unique user name across all users.
You cannot ensure a unique value across many multiple nodes in Firebase's security rules. You instead will need to store the user names as keys in a separate collection, i.e.
usernames
"rexyou0831": "ik3sf...."
The above data structure indicates that user ik3sf... claimed name rexyou0831. With such a structure in place, user names are guaranteed to be unique since keys must by definition be unique in a collection. You can ensure that users can only write new names or delete their own name with:
{
"rules": {
"usernames": {
"$name": {
".write": "!data.exists() || newData.val() === data.val()"
}
}
}
}
To enforce uniqueness of the email addresses too, you will need to create a similar collection for those.
For more explanation read one of the previous questions covering this same topic:
Firebase android : make username unique
Enforcing unique usernames with Firebase simplelogin
Firebase Database Rules for Unique Usernames
How do you prevent duplicate user properties in Firebase?
I've been stuck on this problem for many hours now, so any help is appreciated. Trying to make an Android app with Firebase for user authentication (simple-login email and password) along with unique usernames. I have my sign-up screen fields laid out on a single screen e.g.:
"Enter Username"
"Enter Email Address"
"Enter Password"
I'm very confused as how how to query the database to check if the username exists or not without reading a database snapshot and without attempting to write the username to the database (because this is happening while the user is in state auth == null, so while on the sign-up page before the user has created his account I want to inform the user whether his username is taken or not).
I mean, this feels like it should be very simple, just a simple query to Firebase with a string and just getting Firebase to return True or False, but after hours of googling I could find nothing.
The reason I don't want to use a snapshot to do this is because I do not want to expose all my user's names and their UIDs to the public by setting "read" to true (I followed this guide so my security rules are set up just like this, along with my database structure Firebase android : make username unique).
Here are my rules, and they work currently (I don't like the fact that the read is set to True which is why I'm asking the question though):
{
"rules": {
"usernames": {
".read": true,
"$username": {
".write": "auth !== null && !data.exists()"
}
},
"users": {
"$uid": {
".write": "auth !== null && auth.uid === $uid && !data.exists()",
".read": "auth !== null && auth.provider === 'password' && auth.uid === $uid",
"username": {
".validate": "(!root.child('users').child(newData.val()).exists() || root.child('usernames').child(newData.val()).val() == $uid)"
}
}
}
}
}
And this is my data:
{
"usernames" : {
"abcd" : "some-user-uid"
},
"users" : {
"\"some-user-uid\"" : {
"username" : "abcd"
}
}
}
Thanks!
There is unfortunately, no way to test whether the data exists without actually downloading it via the SDK. Data structures are going to be supreme here (recommended reading: NoSQL Data Structures and you shouldn't be afraid to denormalize a bit of data when optimization and scale are critical.
Generally speaking, you should keep your data well structured so payloads are small and fetch it. If you're fetching something that can't wait for the bytes to be fetched (e.g. games, strange one-off admin ops on very large data sets, et al) then here are a few reasonable approaches to simulate this:
Fetching a list of keys via the REST API
Using the attribute shallow=true in a call to the REST API will prevent loading of a large data set and return only the keys at that path. Note that if you store a million records, they still have to be loaded into memory on the server (slow) and you still have to fetch a million strings (expensive).
So one way to check the existence of data at a path, without actually downloading the data, would be to make a call to the path, such as https://<YOUR-FIREBASE-APP>.firebaseio.com/foo.json?shallow=true, and check whether any keys are returned.
Creating a denormalized index you can query instead
If you really need to squeeze some extra performance and speed out of your Firebase Database (hint: you don't need this unless you're running millions of queries per minute and probably only for gaming logic and similar), you can dual-write your records (i.e. denormalize) as follows:
/foo/data/$id/... data goes here...
/foo/index/$id/true (just a boolean value)
To dual write, you would use the update command, and a write similar to the following (Android SDK sample):
public void addRecord(Map<String, Object> data) {
DatabaseReference db = FirebaseDatabase.getInstance().getReference();
// create a new record id (a key)
String key = db.child("foo").push().getKey();
// construct the update map
Map<String, Object> dualUpdates = new HashMap<>();
dualUpdates.put("/data/" + key, /* data here */);
dualUpdates.put("/index/" + key, true);
// save the new record and the index at the same time
db.child("foo").updateChildren(dualUpdates);
}
Now to determine if a record exists, without actually downloading the data, I can simply query against /foo/index/$id and try DataSnapshot.exists(), at the cost of downloading a single boolean.
Is there any way to clear data stored in Firebase Database persistence enabled via setPersistenceEnabled(true)?
Or eventually prevent read access to previously stored users data on the device?
And extra question - is there any way to check if any data is waiting to sync?
In my app I want to clear db when user is logging out and he confirm that unsynchronized changes will be removed. This app will be used on tablet by many people, and there'll be many data stored per user, so I want to clear unnecessary data stored on the device to:
shrink storage usage
prevent unauthorized person from read users data
It's a security flaw because any user, regardless of whether is signed in or not, has read access to all previously downloaded data! Fortunately we haven't write access there.
I tried to clear db on my own, in both offline and online mode, but data still persist on the device:
// first clear all data on my own
FirebaseDatabase db = FirebaseDatabase.getInstance();
db.goOffline(); // even when I clear db in online mode data persist on mobile device
db.getReference().setValue(null);
// and then logout
FirebaseAuth.getInstance().signOut();
db.goOnline();
eg data structure:
{
"someList": {
"userId1": {
"itemId11": {
"name": "name 11"
},
"itemId12": {
"name": "name 12"
},
...
"itemId1N": {
"name": "name 1N"
}
}
"userId2": {
"itemId21": {
"name": "name 21"
},
"itemId22": {
"name": "name 22"
},
...
"itemId2N": {
"name": "name 2N"
}
}
}
}
my rules:
{
"rules": {
".read": "false",
".write": "false",
"someList": {
"$uid": {
".read": "$uid === auth.uid",
".write": "$uid === auth.uid"
}
}
}
}
Unfortunately there's no supported way to clear the persistence cache. You could try to manually delete the SQLite database used by Firebase Database (should be under /databases/ in your app's data folder), but you'd need to do it before initializing Firebase Database, so you'd have to force the app to restart after signing somebody out or similar.
Regarding knowing if there's "data waiting to sync", assuming you're talking about writes, the only way is to attach CompletionListeners to every write operation you do, and wait for them to complete.
Both of these are things we'd like to improve in future versions of the Firebase Database SDK.
clearPersistence() was launched in v6.2.0.
via
https://github.com/firebase/firebase-js-sdk/issues/449
if (Build.VERSION_CODES.KITKAT <= Build.VERSION.SDK_INT) {
((ActivityManager) getContext().getSystemService(ACTIVITY_SERVICE))
.clearApplicationUserData();
}
source
Oh dear what a terrible hack this solution is, I apologise in advance...
This works tho, to clear the local cache:
disable persistence
take a full copy of the new node, e.g. for user 2
e.g. var copyData = await (await ref.once()).value;
enable persistence
replace the new node, e.g. user 2, with the copyData
In theory only data which has been changed will be written, which should mean no changes to the realtime database. Meanwhile the local cache is replaced with the data from the server.
I got this approach to work for my needs. It's the basis of a solution, which would be different depending on every use case.
Good luck!