This commit fixes another privilege escalation issue
abusing the inter-node communication of distributed
servers to obtain/modify the server configuration.
The inter-node communication is authenticated using
JWT-Tokens. Further, IAM users accessing the cluster
via the web UI also get a JWT token and the browser
will add this "user" JWT token to each the request.
Now, a user can extract that JWT token an can craft
HTTP POST requests for the inter-node communication
API endpoint. Since the server accepts ANY valid
JWT token it also accepts inter-node commands from
an authenticated user such that the user can execute
arbitrary commands bypassing the IAM policy engine
and impersonate other users, change its own IAM policy
or extract the admin access/secret key.
This is fixed by only accepting "admin" JWT tokens
(tokens containing the admin access key - and therefore
were generated with the admin secret key). Consequently,
only the admin user can execute such inter-node commands.
registering notFound handler more than once causes
gorilla mux to return error for all registered paths
greater than > 8. This might be a bug in the gorilla/mux
but we shouldn't be using it this way. NotFound handler
should be only registered once per root router.
Fixes#6915
Rolling update doesn't work properly because Storage REST API has
a new API WriteAll() but without API version number increase.
Also be sure to return 404 for unknown http paths.
xl.json is the source of truth for all erasure
coded objects, without which we won't be able to
read the objects properly. This PR enables sync
mode for writing `xl.json` such all writes go hit
the disk and are persistent under situations such
as abrupt power failures on servers running Minio.
