You can do it by adding Scopes when requesting the initial login. There is an excellent sample is explained here
Bit of code:
List<string> scope = newList<string>() { "email", "user_about_me", "user_hometown", "friends_about_me", "friends_photos" };
var x = newFacebookAuthenticationOptions();
x.Scope.Add("email");
x.Scope.Add("friends_about_me");
x.Scope.Add("friends_photos");
x.AppId = "636919159681109";
x.AppSecret = "f3c16511fe95e854cf5885c10f83f26f";
x.Provider = newFacebookAuthenticationProvider()
{
OnAuthenticated = async context =>
{
//Get the access token from FB and store it in the database and
//use FacebookC# SDK to get more information about the user
context.Identity.AddClaim(
new System.Security.Claims.Claim("FacebookAccessToken",
context.AccessToken));
}
};
x.SignInAsAuthenticationType = DefaultAuthenticationTypes.ExternalCookie;
app.UseFacebookAuthentication(x);