How do you change MongoDB user permissions? - mongodb

Question

For instance, if I have this user:
> db.system.users.find()
{ "user" : "testAdmin", "pwd" : "[some hash]", "roles" : [ "clusterAdmin" ], "otherDBRoles" : { "TestDB" : [ "readWrite" ] } }
And I want to give that user the dbAdmin permissions on the TestDB database, I can remove the user record then add it back with the new permissions:
> db.system.users.remove({"user":"testAdmin"})
> db.addUser( { user: "testAdmin",
pwd: "[whatever]",
roles: [ "clusterAdmin" ],
otherDBRoles: { TestDB: [ "readWrite", "dbAdmin" ] } } )
But that seems hacky and error-prone.
And I can update the table record itself:
> db.system.users.update({"user":"testAdmin"}, {$set:{ otherDBRoles: { TestDB: [ "readWrite", "dbAdmin" ] }}})
But I'm not sure if that really creates the correct permissions - it looks fine but it may be subtly wrong.
Is there a better way to do this?

Answer 1

If you want to just update Role of User. You can do in the following way
db.updateUser( "userName",
{
roles : [
{ role : "dbAdmin", db : "dbName" },
{ role : "readWrite", db : "dbName" }
]
}
)
Note:- This will override only roles for that user.

Answer 2

See array update operators.
> db.users.findOne()
{
"_id" : ObjectId("51e3e2e16a847147f7ccdf7d"),
"user" : "testAdmin",
"pwd" : "[some hash]",
"roles" : [
"clusterAdmin"
],
"otherDBRoles" : {
"TestDB" : [
"readWrite"
]
}
}
> db.users.update({"user" : "testAdmin"}, {$addToSet: {'otherDBRoles.TestDB': 'dbAdmin'}}, false, false)
> db.users.findOne()
{
"_id" : ObjectId("51e3e2e16a847147f7ccdf7d"),
"user" : "testAdmin"
"pwd" : "[some hash]",
"roles" : [
"clusterAdmin"
],
"otherDBRoles" : {
"TestDB" : [
"readWrite",
"dbAdmin"
]
},
}
Update:
MongoDB checks permission on every access. If you see operator db.changeUserPassword:
> db.changeUserPassword
function (username, password) {
var hashedPassword = _hashPassword(username, password);
db.system.users.update({user : username, userSource : null}, {$set : {pwd : hashedPassword}});
var err = db.getLastError();
if (err) {
throw "Changing password failed: " + err;
}
}
You will see — operator changes user's document.
See also system.users Privilege Documents and Delegated Credentials for MongoDB Authentication