Merge branch '20492-access-token-scopes' into 'master'

Resolve "Add a doorkeeper scope suitable for authentication"

## What does this MR do?

- Add a single new scope (in addition to the `api` scope we've had) - `read_user`
- Allow creating OAuth applications and Personal access tokens with a scope selected
- Enforce scopes in the API

## What are the relevant issue numbers?

- Closes #20492 
- EE counterpart for this MR: gitlab-org/gitlab-ee!946

See merge request !5951

2 files changed, 32 insertions, 42 deletions

diff --git a/app/services/access_token_validation_service.rb b/app/services/access_token_validation_service.rb
new file mode 100644
index 00000000000..ddaaed90e5b
--- /dev/null
+++ b/app/services/access_token_validation_service.rb
@@ -0,0 +1,32 @@
+AccessTokenValidationService = Struct.new(:token) do
+  # Results:
+  VALID = :valid
+  EXPIRED = :expired
+  REVOKED = :revoked
+  INSUFFICIENT_SCOPE = :insufficient_scope
+
+  def validate(scopes: [])
+    if token.expired?
+      return EXPIRED
+
+    elsif token.revoked?
+      return REVOKED
+
+    elsif !self.include_any_scope?(scopes)
+      return INSUFFICIENT_SCOPE
+
+    else
+      return VALID
+    end
+  end
+
+  # True if the token's scope contains any of the passed scopes.
+  def include_any_scope?(scopes)
+    if scopes.blank?
+      true
+    else
+      # Check whether the token is allowed access to any of the required scopes.
+      Set.new(scopes).intersection(Set.new(token.scopes)).present?
+    end
+  end
+end
diff --git a/app/services/oauth2/access_token_validation_service.rb b/app/services/oauth2/access_token_validation_service.rb
deleted file mode 100644
index 264fdccde8f..00000000000
--- a/app/services/oauth2/access_token_validation_service.rb
+++ /dev/null
@@ -1,42 +0,0 @@
-module Oauth2::AccessTokenValidationService
-  # Results:
-  VALID = :valid
-  EXPIRED = :expired
-  REVOKED = :revoked
-  INSUFFICIENT_SCOPE = :insufficient_scope
-
-  class << self
-    def validate(token, scopes: [])
-      if token.expired?
-        return EXPIRED
-
-      elsif token.revoked?
-        return REVOKED
-
-      elsif !self.sufficient_scope?(token, scopes)
-        return INSUFFICIENT_SCOPE
-
-      else
-        return VALID
-      end
-    end
-
-    protected
-
-    # True if the token's scope is a superset of required scopes,
-    # or the required scopes is empty.
-    def sufficient_scope?(token, scopes)
-      if scopes.blank?
-        # if no any scopes required, the scopes of token is sufficient.
-        return true
-      else
-        # If there are scopes required, then check whether
-        # the set of authorized scopes is a superset of the set of required scopes
-        required_scopes = Set.new(scopes)
-        authorized_scopes = Set.new(token.scopes)
-
-        return authorized_scopes >= required_scopes
-      end
-    end
-  end
-end