Looks like you have the wide links setting to yes, which is what got me recently.

It's probably due to the permissions on /some/directory, following your example above.

If you don't want to change the file permissions, then you need to tell Samba to use a different local user for that share. That's really your only two options.

I think the force user and force group options is what you want. You will not have an optimum security situation if you force user to root, but it may be what you are looking for.