I have a rails application 'A' which runs on iframe of another application 'B'. I am setting some values on session when the application 'A' is loaded to iframe of 'B'. When the users does certain actions of application 'B', I want to destroy those session values. So, I created a simple API method which just deletes the session values. Whenever the API to delete session value is called API call is success however the session value doesn't seem to exists in the method.
I used three methods that is supposed to work. But it is not working. The API::AController method is:
def delete_session_value
session.key?(:value) # Returns false here
reset_session # 1
session[:value] = nil # 2
session.delete(:value) # 3
end
The session is set from ApplicationController with simple assignment session[:value] = 'something'. The session value is accessible throughout the application. Is the session value not accessible to API controller? Is there any other way I can solve this problem without affecting the flow?
If you session storage is cookie based (which by default, is), then it's a correct behaviour. You cannot read session cookies (or any other cookies) from iframe. See https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy.
If this is same origin request you could try to set your x-frame-optionsheader to SAMEORIGIN. https://developer.mozilla.org/pl/docs/HTTP/X-Frame-Options
Related
From what I have been seeing in my app, if I my controller using an AngularJs $http.get request, I can't update session data in the controller that handles this request because a render :json=> data type response doesn't update the session cookie on the client. I'm not sure that is actually true, but that what seems to be happening.
If it is true though it seems like if I use devise, for example, and initialize a a session variable, e.g. session[:foo]="bar" in session#create, and then subsequently I have an angular module which executes a $http.get, which is handled by, say, account#my_method, as follows
def my_method
session[:foo]="baz"
[do something]
render :json => {status: "OK"}
end
the session[:foo] change will not be persisted in the user's session cookie thus the next time the user hits a controller session[:foo] will still equal "bar", not "baz".
It seems unlikely, but that looks like what I'm seeing as I debug my application. If so would using a database or memcache session store work better, since the change would happen server side and would not require updating the client side cookie? Or is there a way to handle session updates when using Ajax type methods like $http.get in AngularJs
I have some controller. In this controller I get OpenStruct object and want to save it to app session. Next code works fine:
session[:info] = OpenStruct.new(first_field: 1, second_field: 'two')
p session[:info] right after this line prints
#<OpenStruct first_field=1, second_field="two">
But after this I do redirect to another controller, and when I write p session[:info] in this controller I get
{"table"=>{"first_field"=>1, "second_field"=>"two"}}
So, why do I get this, and how can I load correct OpenStruct instance?
A session usually consists of a hash of values and a session id,
usually a 32-character string, to identify the hash. Every cookie sent
to the client's browser includes the session id. And the other way
round: the browser will send it to the server on every request from
the client.
You should either serialize your objects before storing them in the session.
session[:info] = OpenStruct.new(first_field: 1, second_field: 'two').to_yaml
and retrieve it using
YAML.load(session[:info])
from the rails documentation
Do not store large objects in a session. Instead you should store them
in the database and save their id in the session. This will eliminate
synchronization headaches and it won't fill up your session storage
space (depending on what session storage you chose, see below). This
will also be a good idea, if you modify the structure of an object and
old versions of it are still in some user's cookies. With server-side
session storages you can clear out the sessions, but with client-side
storages, this is hard to mitigate.
or change your session store from cookie_store to cache_store
In your environment change
config.session_store :cookie_store
to
config.session_store :cache_store
In Rails, I have implemented the below code for user auth (confirmed to be correct). However, I wanted to confirm my thinking for this strange session[:session_token]. is this the "cookie" that is stored in the browser?
class ApplicationController < ActionController::Base
protect_from_forgery with: :exception
helper_method :current_user, :signed_in?
private
def current_user
#current_user ||= User.find_by_session_token(session[:session_token])
end
def signed_in?
!!current_user
end
def sign_in(user)
#current_user = user
session[:session_token] = user.reset_token!
end
def sign_out
current_user.try(:reset_token!)
session[:session_token] = nil
end
def require_signed_in!
redirect_to new_session_url unless signed_in?
end
end
My understanding so far of how this works is that whenever the browser/client sends a request to rails, the cookie (with the session[:session_token]) is also sent over, thus allowing the current_user method to find the user. Is my understanding correct? This is strange to me because there's a gap of knowledge of how exactly the browser/client gets access to the session cookie when we declare it in ApplicationController (Rails-side).
You are pretty much there. Although, I have a feeling you might be confusing apples with oranges...
Sessions:
Very often in dynamic web sites one would want to store user data between HTTP requests (because http is stateless and you can't otherwise associate a request to any other request), but you don't want that data to be readable and/or editable on the client-side inside of the URL (like.. yourwebsite.com/yourPage?cookie=12345&id=678), and so on..., because you don't want the client to play around with that data without passing through your server-side code.
One way to solve this problem is to store that data server-side, give it a "session_token"(as you called it), and let the client only know (and pass back at every http request) that token. This is how the session is implemented.
Cookies:
The most common technique for implementing sessions in Rails involve using cookies, which are small pieces of text placed on the user’s browser. Because cookies persist from one page to the next, they can store information (such as a session_token or whatever else you want) that can be used by the application to retrieve the logged-in user from the database.
Where is the Session Stored in Rails?
Using both of the above concepts I can now tell you that the default session store inside of Rails is CookieStore, which is about 4KB in size.
To put it simply...
def sign_in(user)
#current_user = user
session[:session_token] = user.reset_token!
end
...method that you defined places the user into a temporary session.
Then the idea is that the following...
def current_user
#current_user ||= User.find_by_session_token(session[:session_token])
end
...method would find and retrieve the user from the database corresponding to the session token and initialize it to a variable you specified.
Additional info:
You should also note that there is an important difference between Rails's session and cookies helper methods...
They both generate cookies, however, session[...] method generates temporary cookies, which should expire upon the browser exit, and cookies[...] method creates persistent cookies, which do not.
Additionally, I would suggest having a look at Section 2 of Ruby on Rails Security guide. You might find it useful.
Hope this helps you out.
Session is stored in server side. And,
Cookie is stored in client side (in browser cookie). And,
When client/browser send a request to rails server, every time cookies are sent to rails server.
When a session is set in rails server, like: session[:user_id] = 4,
Rails store it in server side.
Session is saved in server side like key value pair (like json object)
For each browser, Rails set a session identifier in cookie, so that, Rails can find the correct session information for a request.
Without session identifier in cookie, Rails do not know, what session belongs to what browser.
So, session will not work without cookie.
Edit: Explain: sessions are stored server side
Suppose, I am using your web application, and after login I will be redirected to home page.
I open login page, input username and password, and click login button.
The form is submitted to sessions#login action.
in sessions#login - you check username and password - and set session[:session_token]:
if username and password is correct
random_unique_identifier_string = #user.remember_token
session[:session_token] = random_unique_identifier_string
redirect_to root_url
end
When server run this code session[:session_token], server need an unique identifier for each browser session.
So, server generate an unique identifier for this browser, such as: abc123
Server set all session variables in a place (may be in some folder or in database), label this folder as abc123.
Now server send a cookie request to browser - to set cookie _ebook_session = abc123.
(I see, if my app name is ebook, in rails, cookie name is like: _ebook_session)
Now the page redirect to home page.
** Note: Everything above happen in single request **
Now, in my browser, I want to open some page that need authentication (suppose, dashboard page).
You added before_action: require_signed_in! in dashboard controller.
So, when I open dashboard page in my browser, browser by default send all cookies with every request. so _ebook_session cookie is sent to server. Your server gets the value of _ebook_session cookie is abc123. Now your application know we need to look in abc123 folder for session. Now you can get value of session[:session_token] from abc123 folder.
** I have explained second request above **
Each browser needs unique session identifier.
Important: _ebook_session cookie will be set in browser in first request. If we already have _ebook_session cookie set in a browser, we do not need to set it again, second, third and next requests in that specific browser.
I hope, you understand.
How do I delete the session but keep the cookies? I'm trying to simulate a browser close/reopen.
In your step definitions you can access the session directly and remove any/all of your critical values. Assuming that you're trying to test login/logout you could remove the user_id value from the session.
session[:user_id] = nil
Background
I'm an experienced web developer (mostly with Python and CherryPy) who has implemented secure session management from scratch before, and is now learning Rails. I'm investigating the behavior of Rails sessions as exposed by the session object that is available in the ActionController instance and view contexts.
Question/Problem
I have read that the default implementation of sessions in Rails 4 uses an encrypted and tamper-proof cookie. Cool, I guess that means I can use it to hold a user ID for user sessions without worrying about session forging (tamper-proof) or anyone being able to find out what their ID is (encrypted). I wanted to test this and see what rails would do if the session cookie was altered.
So, I went and altered the content of the session cookie attribute using a browser add-on, and when I reload the page with the new cookie value, Rails just happily gives me different new values for session_id and _csrf_token.
What happened to session cookie integrity!?
Shouldn't rails detect (via HMAC signature) that the cookie was altered and then tell me about it somehow?
I'm terrified that I'm missing something obscenely obvious, but I've been having no luck searching for an answer on the web, and the source code isn't giving it up easily either (I'm new to ruby). Thanks in advance.
The Experiment
I created a new app and generated a controller with an index action:
$ rails new my_app
$ cd my_app; rails g controller home index
Then I added these two lines to the app/views/layouts/application.html.erb file:
<%= session.keys %><br/>
<%= session.values %>
I started up the dev server and navigated my browser to "localhost:3000/home/index". As expected, the page has the following lines at the bottom:
["session_id", "_csrf_token"]
["8c1558cabe6c86cfb37d6191f2e03bf8", "S8i8/++8t6v8W8RMeyvnNu3Pjvj+KkMo2UEcm1oVVZg="]
Reloading the page gives me the same values, although the app sets a new value of the _my_app_session cookie attribute every time. That seems weird to me, but I'm getting the same session hash values, so I guess it's cool.
Then, I used a cookie editing add-on for Chrome to alter the value of the _my_app_session cookie attribute (replacing the first character of the attribute value). Reloading the page shows completely different values without anything happening. WAT?
I can't claim a really thorough understanding of the code here. But I can tell you this much:
I followed your steps exactly (using Ruby 2.0.0-p247 & Rails 4.0), with one exception -- I also added the 'byebug' gem to my Gemfile and inserted a debugging breakpoint in the HomeController#index action.
From the byebug console, at that breakpoint, I could see the unedited session cookie via:
(byebug) cookies["_my_app_session"]
"cmtWeEc3VG5hZ1BzUzRadW5ETTRSaytIQldiaTMyM0NtTU14c2RrcVVueWRQbncxTnJzVDk3OWU3N21PWWNzb1IrZDUxckdMNmZ0cGl3Mk0wUGUxU1ZWN3BmekFVQTFxNk55OTRwZStJSmtJZVkzVmlVaUI2c2c5cDRDWVVMZ0lJcENmWStESjhzRU81MHFhRTN4VlNWRlJKYTU3aFVLUDR5Y1lSVkplS0J1Wko3R2IxdkVYS3IxTHA2eC9kOW56LS1IbXlmelRlSWxiaG02Q3N2L0tUWHN3PT0=--b37c705a525ab2fb14feb5f2edf86d3ae1ab03c5"
And I could see the actual encrypted values with
(byebug) cookies.encrypted["_my_app_session"]
{"session_id"=>"13a95fb545a1e3a2d4e9b4c22debc260", "_csrf_token"=>"FXb8pZgmoK0ui0qCW8W75t3sN2KLRpkiFBmLbHSfnhc="}
Now, I edit the cookie by changing the first letter to "A" and refresh the page:
(byebug) cookies["_my_app_session"]
"AmtWeEc3VG5hZ1BzUzRadW5ETTRSaytIQldiaTMyM0NtTU14c2RrcVVueWRQbncxTnJzVDk3OWU3N21PWWNzb1IrZDUxckdMNmZ0cGl3Mk0wUGUxU1ZWN3BmekFVQTFxNk55OTRwZStJSmtJZVkzVmlVaUI2c2c5cDRDWVVMZ0lJcENmWStESjhzRU81MHFhRTN4VlNWRlJKYTU3aFVLUDR5Y1lSVkplS0J1Wko3R2IxdkVYS3IxTHA2eC9kOW56LS1IbXlmelRlSWxiaG02Q3N2L0tUWHN3PT0=--b37c705a525ab2fb14feb5f2edf86d3ae1ab03c5"
(byebug) cookies.encrypted["_my_app_session"]
nil
So the session is nil at this point in the request:
(byebug) session
#<ActionDispatch::Request::Session:0x7ff41ace4bc0 not yet loaded>
I can force loading the session with
(byebug) session.send(:load!)
and when I do, I see that the resulting session id is
"f6be13fd646962de676985ec9bb4a8d3"
and sure enough, when I let the request finish, that's what I see in the view:
["session_id", "_csrf_token"] ["f6be13fd646962de676985ec9bb4a8d3", "qJ/aHzovZYpbrelGpRFec/cNlJyWjonXDoOMlDHbWzg="]
I also have a new cookie value now, unrelated to the one I edited.
So from this I think we can conclude is that what's happening is that since the cookie signature could not be verified, the session was nullified and regenerated. I now have a new session, with a different csrf_token.
The relevant code appears at actionpack/lib/action_dispatch/middleware/cookies.rb:460-464, in the EncryptedCookieJar class:
def decrypt_and_verify(encrypted_message)
#encryptor.decrypt_and_verify(encrypted_message)
rescue ActiveSupport::MessageVerifier::InvalidSignature, ActiveSupport::MessageEncryptor::InvalidMessage
nil
end
Rather than decrypting a message with an invalid signature, we just treat it as nil. So the unverifiable cookie that stores the session id and csrf token is not used to load the session, and anything that depends on the values in the cookie will fail.
So why didn't we get an error rather than just a new session? That's because we didn't try anything that depends on the encrypted values. In particular, although we have
protect_from_forgery with: :exception
(as opposed to :null_session) in ApplicationController, Rails does not verify the csrf token on GET or HEAD requests -- it relies on the developer to implement these actions according to spec, so that they're non-destructive. If you tried the same thing on a POST request, you'd get an ActionController::InvalidAuthenticityToken error (as you can easily verify for yourself).