[CentOS] Re: vfstp and renaiming of files with ftp client

Fri Jul 14 11:44:03 UTC 2017
Yamaban <foerster at lisas.de>

On Fri, 14 Jul 2017 07:53, Götz Reinicke - IT Koordinator wrote:
> Am 13.07.17 um 17:10 schrieb Tris Hoar:
>> On 13/07/2017 14:38, Götz Reinicke - IT Koordinator wrote:
>>> Am 13.07.17 um 14:46 schrieb Pete Biggs:
>>>>> I have a vsftp server and two users for up and download.
>>>>> If user Alice uploads a file, the owner is set to Alice as expected
>>>>> "-rw-r--r-- alice ftpuploadgroup"
>>>>> Now Bob can login to the same folder and is able to rename the
>>>>> uploaded
>>>>> file.
>>>>> Bob can also rename an uploaded folder, but can't rename a file in
>>>>> that
>>>>> folder ....
>>>>> I'm confused, as I don't get why this is possible at all.
>>>> What are the permissions and ownership on the directory the uploads go
>>>> in? If its group is 'ftpuploadgroup' and has group write permissions
>>>> than any member of that group can rename files in that directory. If a
>>>> user creates a directory, then that will have rwxr-xr-x permissions so
>>>> they won't be able to rename files within that directory.
>>> The permissions for the upload folder are drwx-wx--- and the owner is
>>> Bob group is ftpuploadgroup
>>> Alice is member of that group, but should only drop files in.
>>> The files are ownd by Alice, and I'm bit iritated, taht Bob can rename
>>> tham ... as Bob only has read permision (from the group)
>>> The files in a subfolder have the same permissions and Bob cant change
>>> tham...
>>>      Thanks for your feedback . /G
>> He does not have read only permission from the group. He is the folder
>> owner and so can change things within that folder. You need to change
>> the folder to something other than Bob.
>> The sub dir does not have the same permissions. Alice is the owner.
>> What is the end goal you want. E.g. Bob and Alice and can upload, Bob
>> can read files both he and Alice upload but Alice can only read her
>> files. Perhaps we can suggest permissions that would do what you want?
> Thanks Tris, thanks Peter,
> the goal is, that the FTP server is a Dropbox for Alice, so she can
> upload files and folders and is not able to see the uploaded files
> (drwx-wx--- for the main older).
> Bob should be able to rename the files and folders by ftp. (and of
> course be able to download them.)
> If this is not possible with the standad permissions, I'm fine, in the
> past Users did not try to upload folders and others did not rename
> ...Than we look for an other workflow.
> But hey, may be you have an idea on a god permission set.
>    Regards . Götz

At least one possibilities with "standard unix permissions":
The Dropbox-Folder and any subfolders are owned by user Bob and
the ftpuploadgroup group with rights (drwx-wx---) or even added
setgid bit (drwx-ws---).
That way user Alice can upload files into these folders, but can't
see into the folders, while Bob as the owner of the folder has the
needed rights to manage the contents.
But if the files / sub-folders have no group write bit the things get
iffy in a very subtle and ugly way.

So your dropbox folder should look like this:
ls -la dropbox-folder
drwx-ws--- bob   ftpuploadgroup  60 14. Jul 13:13 .
dr-xr-xr-x ftp   ftp            120 14. Jul 13:12 ..
-rw-rw-r-- alice ftpuploadgroup 421 14. Jul 13:13 test-drop-file

IMHO the first thing Bob should do is to set group write bit, 
claim ownership of the files, then move them elsewhere.
chmod -R g+w dropbox-folder/*
chown -R bob:ftpuploadgroup dropbox-folder/*
mv -t target-dir dropbox-folder/*

If necessary, put the first two commands (with absolute paths)
into a shell script, mark it executeable put it in /usr/local/bin
and allow Bob to use it with sudo.

YMMV, but at least for me this arangement works.
  - Yamaban.