Download files a linux user to a specific folder?

Create an application that allows users to upload files to my server via sftp. For this you need the server to create a user with certain rights. Rights such :
the user can upload files only to a specific folder;
the size of the files in the folder should be less than 100 MB;
The user is unable to do anything but download the files (even delete their own uploaded files).

How can I implement it?
June 3rd 19 at 20:20
3 answers
June 3rd 19 at 20:22
proper rights, the proper umask and quotas Domashnaya directory
you can link for reference? - Simeon_Senger11 commented on June 3rd 19 at 20:25
June 3rd 19 at 20:24
Why can't you do this limitation to make in your app?

Read the help on sftp server such as the vsftp able to do quota and lochit users in their home directory.
Because the user is able to circumvent the restriction if I want to. - Simeon_Senger11 commented on June 3rd 19 at 20:27
June 3rd 19 at 20:26
afaik the size of the file in the folder in any way by means of the OS/FS is not regulated, only the limit on the total amount. Perhaps sftp servers know how to do something similar, even very likely, all of your wishlist will be possible to steer through the config SFTP servers. Google suggests that SFTP the client will be the same and the ssh connection, as a matter of fact this is all happening on top of school. So rights only a record you can put on a folder via the OS.
about the limits:

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