I can't figure out how to write a Firestore rule that reflects: "when the user requests a doc from the messages collection, check that the doc above that "messages" collection includes a field thats an array which includes their uid. I've gotten the rule to work on the top level but if I try to access a document inside a collection, which is inside the "chats" collection, the user is denied.
Here's my relevant rule:
match /chats/{chatId}/{allChildren=**} {
allow read, update: if request.auth.uid in resource.data.usersUids;
}
This works (the chatId doc has an array of uids):
await db.collection("chats").doc(chatId).get()
This does not work (none of the messages have an array of uids):
await db.collection("chats").doc(chatId).collection("messages").get()
It seems like the heart of the issue is that I'm trying to get the resource.data of the messages collection rather than the resource of the chatId doc, but I can't figure out to solve this.
resource only contains the data from the specific document that was matched by the entire path. It doesn't contain anything from any parent documents that appear in that path.
Any time you want to use fields from a document that wasn't matched by the full path, you have to get() the document using its own full path as described in the documentation. For example:
match /chats/{chatId}/{allChildren=**} {
allow read, update: if request.auth.uid in get(/databases/$(database)/documents/chats/$(chatId)).data.usersUids;
}
Related
I have a firestore with a collection called "children" and a subcollection called events. The children documents have an array called "caretakers" which contains the authids for users that should have access to this document. My question is, what is the right way to secure the subcollection. I am currently doing the following:
match /children/{childId} {
allow read, write, delete, list:
if request.auth.uid in resource.data.caretakers;
allow create:
if true;
}
match /children/{childId}/events/{eventId} {
allow read,write,delete,get:
if request.auth.uid in get(/databases/$(database)/documents/children/$(childId)).data.caretakers
}
Something about that get(...) doesn't feel right to me. Is that necessary? Do I really need to specify rules separately for each subcollection? or if the parent document has permissions.. those permissions should cascade down to subcollections?
With your current structure unfortunately you will indeed need to read the parent document to check against its caretakers role for each subdocument. What's even worse is that this makes queries impossible, as you can't read from the parent document when querying events.
The common workaround for this is to duplicate the caretakers into each events document, so that you can query for it there, and the rules can then secure that only that query is allowed.
Yes you need to explicitly define rules for sub-collections. You can nest the sub-collection's rule in that collection itself to structure it.
Security rules apply only at the matched path, so the access controls defined on the [children] collection do not apply to the [events] subcollection
service cloud.firestore {
match /databases/{database}/documents {
match /children/{childId} {
allow read, write, delete, list: if request.auth.uid in resource.data.caretakers;
allow create: if true;
// These rule will apply for docs in children collection only
// Explicitly define rules for the 'events' subcollection
match /events/{eventId} {
allow read,write,delete,get: if request.auth.uid in get(/databases/$(database)/documents/children/$(childId)).data.caretakers
// This rule will apply for docs in events sub-collections only
}
}
}
}
You can read more about this at: How security rules work?
I'm answering my own question to note what I ended up going with as a solution.
In my case, the number of Users that have access to each {childId} is very low. Therefore, I ended up storing custom claims in the Users Auth object. Basically stored an array of {childId} in the Users auth object instead of storing a bunch of userIds into the Child object.
This allows me to do a direct check to see if the {childId} exists in the users auth object and saves me extra reads of data.
I have a simple fireStore collection named jokes where there is a document per joke.
In a joke, there is a key published: boolean
So the idea is to have a single collection with jokes, but each document can be either published or unpublished. I would not like users to view unpublished jokes.
In my fireStore rules, i have the following:
match /jokes/{id} {
allow read: if get(/databases/$(database)/documents/jokes/$(id)).data.published == true
}
In my application, I want users to be able to see only the published jokes, therefore i use the where
this.$fireStore.collection('jokes').where('published', '==', true).get()
When I do this, the console tells me i got insufficient permissions.
Is it possible to use this pattern, or do I have to use cloud functions to serve the published jokes? Or maybe a separate collection for unpublished ones?
You don't need a get() in the rule for this, as the current document is already available as resource. In fact, that get() is the problem here, as the rules engine cannot statically evaluate that for all document in one go.
match /jokes/{id} {
allow read: if resource.data.published == true
}
Also see the documentation on securely querying data, specifically the section on securing and querying documents based on a field
I've got a Firestore collection.
The IDs of the documents are secrets. You should be able to read only the document whose ID you know.
For the sake of simplicity. I'd like to stick to this approach.
However, by default, one can read an entire collection from Firestore, for example
await firestore.collection("secret_documents").get()
Is it possible to allow reading only one document at once, only when it's referred by its ID?
Yes, that is actually quite easy. To control what documents can be accessed, use Firebase security rules for Firestore.
By default your security rules will be read and write, but those can actually be broken down into more granular operations of get, list, create and update. And what you're trying to do is to allow get, but not a list operation. From the documentation:
service cloud.firestore {
match /databases/{database}/documents {
// A read rule can be divided into get and list rules
match /cities/{city} {
// Applies to single document read requests
allow get: if <condition>;
// Applies to queries and collection read requests
allow list: if <condition>;
}
...
So to allow get for everyone and disallow list calls:
allow get: if true;
allow list: if false;
You'll probably want to elaborate on the allow get rule a bit, because it's more common to restrict it, for example to users that are signed in to your project with Firebase Authentication:
allow get: if request.auth.uid != null;
https://firebase.google.com/docs/firestore/security/rules-query
I'm trying to create a Firestore auth rule that checks the current user against a list of team members in a team document. The members are stored as document references so I've been trying things like this:
match /teams/{document=**} {
allow read: if path("/users/" + request.auth.uid) in resource.data.members;
}
But when I try and access the team document I get told there is an Auth failure.
Each team member has their own document in /users using their UID as a key. So a user might be /users/12345678 and the teams document might have:
/teams/team1 {
members: [/users/12345678, ....]
}
Where the members are Reference types.
So far I've not been able to figure this out as Firestore does not seem to have the concept of a document reference type in it's auth rules.
Any suggestions?
Security rules do have a concept of a reference, and it's represented as a Path type object. When a document reference is read by security rules, you have to treat it like a Path. And that Path will be fully qualified like this:
/databases/$(database)/documents/collection/documentId
Where $(database) comes from your usual top-level database wildcard match.
So, your rule might be implemented like this:
match /teams/{document=**} {
allow read: if /databases/$(database)/documents/collection/users/$(request.auth.uid) in resource.data.members;
}
Note that in security rules, you can build a path simply by starting with a /, and use $(foo) for interpolating variables as path components.
I see that to get a field of a document in security rules one must use get. The example below shows getting the 'admin' field of some document in the users collection. If I wanted to get another field, would I have to do another get request or can I just do one get request and get all the fields I need in the document.
Here is the example I'm referring to in the documentation.
https://firebase.google.com/docs/firestore/security/rules-conditions
service cloud.firestore {
match /databases/{database}/documents {
match /cities/{city} {
// Make sure a 'users' document exists for the requesting user before
// allowing any writes to the 'cities' collection
allow create: if exists(/databases/$(database)/documents/users/$(request.auth.uid))
// Allow the user to delete cities if their user document has the
// 'admin' field set to 'true'
allow delete: if get(/databases/$(database)/documents/users/$(request.auth.uid)).data.admin == true
}
}
}
Yes, you would have to write another get(). There are no variables in Firestore security rules, so you can't store the contents of a get() in order to use its data multiple times.
Multiple gets accessing the same document might not incur multiple read charges. The documentation states:
Some document access calls may be cached, and cached calls do not count towards the limits.