I need to allow a user to read a specific document /customers/cumstomerkey but not to get the whole collection. How can I achieve that? Following rule allows access to get the whole collection:
match /customers/{document=**} {
allow read, write: if true;
}
You will want to read about granular operations in security rules. If you have a single document that should be gettable, just call out the path and allow get access on just that:
match /customers/cumstomerkey {
allow get;
}
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 currently have a rule setup for firebase. Which works for reads when a member is already part of the subcollection.
match /clans/{clanName} {
allow create;
allow read: if exists(/databases/$(database)/documents/clans/$(clanName)/members/$(request.auth.uid));
match /members/{uid} {
allow create;
allow read,write,delete: if uid == request.auth.uid;
}
}
Now i am trying to use a random key generated that is stored on the clan profile to allow reads also.
I am trying by getting the clan document and checking the key then adding if it matches. I would like to just do a request and the rule validate the docid and key are right.
I know that Firebase has the FieldValue class, which can be used to generate e.g. a server-side timestamp when writing a document (link).
What's the preferred practice for inserting the current user's uid into a document?
Having the client provide that field seems to allow misuse - unless I provide a server rule that checks for (new/updated) documents to match the request.auth.uid, something like:
service cloud.firestore {
match /databases/{database}/documents {
match /broadcasts/{broadcast}/chatMessagesCollection/{message} {
allow write: if request.resource.data.uid == request.auth.uid;
allow read: if true;
}
}
}
I can't find anything on the web for the use-case of having a document be populated with the user writing it -- so what's the best take on this?
What you're doing now with security rules to enforce that the provided UID matches the current user is exactly the right thing to do. There is really nothing better (for this specific use case), and this is a common practice.
I've even written about it in this blog series: https://medium.com/firebase-developers/patterns-for-security-with-firebase-per-user-permissions-for-cloud-firestore-be67ee8edc4a
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 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.