How can I set up a common SFTP directory for certain users, mounted with s3fs?

Question

I'm looking to set up a common directory which is writable via SFTP by a certain set of users. This set of users should be able to access only this directory, and only via SFTP.

I have successfully set this up, using the following sshd configuration:

Subsystem sftp internal-sftp

Match Group sftponly
        ChrootDirectory /mnt/filebucket
        ForceCommand internal-sftp
        AllowTcpForwarding no
        PermitTunnel no
        X11Forwarding no
        PasswordAuthentication yes   # temporary for testing

My users are part of the sftponly group, and they can log in and they are successfully chrooted into the directory.

The catch, though, is that I want to mount an S3 bucket (using s3fs) in this /mnt/filebucket directory. Once I mount it, the permissions on the directory change from drwxr-xr-x 2 root root (sshd approves for chroot) to drwxrwxrwx 1 root root (sshd does not approve).

Is there something about how I'm mounting this directory that is causing this issue?

Have you tried changing the permissions after it's mounted with `chmod`? — Patrick, May 22 '17 at 19:34
@Patrick yes: `chmod: changing permissions of ‘/mnt/filebucket’: Input/output error` — Mark, May 22 '17 at 20:07
If I set the ChrootDirectory to /mnt everything works as expected, but then users need to (cd|click) into the extra `filebucket` directory after logging in. Can this be automated? — Mark, May 22 '17 at 20:35

score 0 · Answer 1 · answered May 23 '17 at 11:41

If I set the ChrootDirectory to /mnt everything works as expected, but then users need to (cd|click) into the extra filebucket directory after logging in. Can this be automated?

Yes, you can use -d switch to the internal-sftp, which will specify the starting directory for users.

How can I set up a common SFTP directory for certain users, mounted with s3fs?

1 Answers1