[Samba] Incorrect permissions on mount despite correct options
karmak at karmak.org
Sun Apr 18 07:20:58 GMT 2004
Tim Starr wrote:
> The problem was
> that it was/is being mounted under the following permissions:
> tstarr at host:~/mount$ ls -l
> total 0
> drwxr-xr-x 1 501 dialout 0 Apr 7 20:39 Audio
> drwxrwxr-x 1 501 dialout 0 Apr 9 01:29 Desktop
> Now I have no user 501 on my system and no dialout group either. Odd.
With Linux kernel 2.6.x and 2.4.25+, CIFS Unix extensions are in effect,
allowing you to view and manipulate Unix-y things like symlinks and
suid/sgid files using Samba.
This also has the effect that the Unix UIDs and GIDs from the server get
passed to the client.
If you look on the server, you'll see that "501" is the numeric ID for
the user that actually owns the file. And though you may not be aware of
it, you *should* have a group called "dialout" on the Linux machine.
(Look at /etc/group to confirm.) You'll notice that the numeric ID for
the "dialout" group on your Linux machine maps to the numeric ID for the
file's group on the server.
[In case you were wondering what the point of this is, these changes
make Samba play nicer with Unix machines. It makes it possible to
replace something like NFS with Samba.]
In the 2.4 series (as of 2.4.25), the Unix extensions are an optional
configuration of the Linux kernel (i.e. you enable or disable this when
building the kernel). I haven't looked at 2.6 yet, but I suspect it's
also optional there. I don't know whether you can turn this behavior off
or on after the kernel is built (using a mount option or a /proc setting
or something), as I just started using it myself.
FWIW, I've encountered a couple pitfalls myself. I think maybe there are
still some issues to work out, so if Samba was previously doing
everything you needed it to and you don't need the Unixy features, you
might want to use a kernel that has these entensions disabled.
(Just a slight caution: I haven't spent a lot of time using Samba, so I
may be a little off with some of the things I just said. If so,
hopefully the experts will set the record straight.)
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