svc: Assume access key creation permission to be available by default (#3306)

Allow SVC creation when CreateServiceAccount is denied with a condition

Adding this policy will make the user not able to create a service account anymore:

```
    {
      "Effect": "Deny",
      "Action": [
              "admin:CreateServiceAccount"
      ],
      "Condition": {
              "NumericGreaterThanIfExists": {"svc:DurationSeconds": "1500"}
      }
    },

```

The reason is that policy.IsAllowedActions() is called with conditions from the user login.

Assume svc account creation to be possible for now until we come up with a better fix

Co-authored-by: Anis Eleuch <[email protected]>
Co-authored-by: Prakash Senthil Vel <[email protected]>

Author: 3 people

api/user_session.go

@@ -139,6 +139,14 @@ func getSessionResponse(ctx context.Context, session *models.Principal) (*models
 
 	defaultActions := policy.IsAllowedActions("", "", conditionValues)
 
+	// Allow Create Access Key when admin:CreateServiceAccount is provided with a condition
+	for _, statement := range policy.Statements {
+		if statement.Effect == "Deny" && len(statement.Conditions) > 0 &&
+			statement.Actions.Contains(minioIAMPolicy.CreateServiceAccountAdminAction) {
+			defaultActions.Add(minioIAMPolicy.Action(minioIAMPolicy.CreateServiceAccountAdminAction))
+		}
+	}
+
 	permissions := map[string]minioIAMPolicy.ActionSet{
 		ConsoleResourceName: defaultActions,
 	}