sshfs & Permission denied

mr.sambo · 07-08-2011, 05:25 PM

Hi,

I have a problem with sshfs

I want to share a binary with some others comptuers, but i only want them to be able to execute (no read/write ).

So, on my main server, i chown root:root bin & chmod 701 bin.
That work nicely on main server, local users can execute bin w/o read/write ...
But when i mount directory using sshfs, users cant exec/read/write ...

Can you help me?

Thanks

SSHFS version 2.2
FUSE library version: 2.8.4
fusermount version: 2.8.4
using FUSE kernel interface version 7.12

Tinkster · 07-08-2011, 06:34 PM

And what are the permissions on the local mountpoint? Which mount-options
did you use?

Cheers,
Tink

mr.sambo · 07-08-2011, 06:38 PM

rw,nosuid,nodev,max_read=65536,user=mylocaluser

Default one

Elv13 · 07-08-2011, 07:01 PM

(this is a theory)

SSHFS is using FUSE userland file system. So any action on the file system is emulated over the SSH connected. The feature set you get must be emulated too. So when the emulator try to read the binary to cache it into a local executable, it hit a permission wall. Applications can't just be executed where they are, they have to be loaded in memory first. For local file system, it imply a kernel mode operation, but FUSE is not a native file system, it is an emulated file system, it just can't enter in kernel mode to do operations.

I think you will have to grant full read access to the files. Who care about reading a binary after all. The worst thing that can happen is making a copy of it.

mr.sambo · 07-08-2011, 07:05 PM

Thats exactly what i want to avoid

T3RM1NVT0R · 07-08-2011, 07:07 PM

Hi there,

Code:

 rw,nosuid,nodev,max_read=65536,user=mylocaluser

If I am not wrong this implies that user=mylocaluser will be able to access/execute binary on that particular mount. Are you able to do that using mylocaluser account.

Did you try using:

Code:

 rw,nosuid,nodev,max_read=65536,users

?

Did you try setting up suid on the source location? Here is a link that will help:
http://www.techcuriosity.com/resourc..._in_linux.php#

and then mounting the sshfs as follows:

Code:

 rw,suid,nodev,max_read=65536,users

Elv13 · 07-08-2011, 07:09 PM

Quote:

Originally Posted by mr.sambo

Thats exactly what i want to avoid

A solution would be to use NFS over SSH or OpenVPN or IpSec instead of SSHFS. It will be slower, but is native. (local) Connection sniffing could still occur, but there is little you can do about it anyway.

Tinkster · 07-08-2011, 07:44 PM

Quote:

Originally Posted by mr.sambo

rw,nosuid,nodev,max_read=65536,user=mylocaluser

Default one

And the perms/ownerships on the local directory you're mounting it to?

mr.sambo · 07-09-2011, 05:12 AM

drwxr-xr-x in local, wihth correct users

Am goin to check about NFS over SSH, maybe will be better