[sshfs] Fwd: Bug in ID mapping if permissions shall be preserved?

[Vivenzio P. <viv...@gm...>]

Hi,

What I forgot to mention: The remote system is Solaris
and does *not* restrict chown. That's why it it possible
that ownership gets changed to a uid not known on the
remote host. (In Linux, this is typically forbidden.)

But nonetheless, I see this as misbehaviour, since
from "sshfs logic", preserving ownership should
mean "if uid/gid mapping is defined and can be
applied, strictly follow this mapping; otherwise preserve
uid/gid".

BR,
Vivenzio

-------- Original-Nachricht --------
Datum: Thu, 17 Nov 2011 09:35:23 +0100
Von: viv...@gm...
An: fus...@li...
Betreff: Bug in ID mapping if permissions shall be preserved?

Hi,

I have the following problem with sshfs under Linux:

I mount a remote directory via sshfs, remote user has "ruid", "rgid".
Local user has "luid", "lgid".

sshfs mount is done with following command:

$ sshfs ruser@rhost: mount-dir -ofollow_symlinks -o idmap=user -o uid=luid,gid=lgid

Copying file over from/to local/remote side works fine (also user mapping
is ok), except in the case when permissions/ownership shall be preserved.

Example: Assume I have mounted sshfs on ~/ruser, so that the home directory of ruser on rhost is seen as a subdirectory in my local home dir.

$ cd  # go to local home dir
$ echo "hello, remote world" > testfile
$ chmod 600 testfile
$ ll testfile 
-rw------- 1 luser users 20 Nov 17 09:21 testfile
$ mv testfile ruser
mv: preserving permissions for `ruser/testfile': Permission denied
$ cat ruser/testfile 
cat: ruser/testfile: Permission denied
$ ls -l ruser/testfile
-rw------- 1 luser 1000 20 Nov 17 09:21 ruser/testfile

As mv command by default wants to preserve ownership and permissions
(I could have used "cp -p" with the same result), the file is copied
to remote host, however uid/gid mapping is not done!

IMO, the "preserve ownership" shall preserve the ownership in a
"logic" way: As remote files of ruser are seen with uid of luser,
uid (and gid) shall be mapped also when trying to "preserve
ownership".

The last "ls -l ruser/testfile" (executed on local host) shows
luser as owner, however if I login on rhost as ruser, I see luid
as owner which is unknown on rhost and leads to above
"permission denied" messages. In other words, uid/gid _is_
preserved, however from the "sshfs POV" this is not correct
(as uid/gid mapping is not done and leads to errors).

Could you tell me if there is a solution to the problem (haven't
found this case by googleing it) or if this is a bug that can
be fixed?

Kind regards,
Vivenzio



-- 
Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir
belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de


-- 
NEU: FreePhone - 0ct/min Handyspartarif mit Geld-zurück-Garantie!		
Jetzt informieren: http://www.gmx.net/de/go/freephone