[Qemu-devel] Does anyone actually use -smb

[Qemu-devel] Does anyone actually use -smb

[Anthony Liguori]

It looks to be broken.  I don't recall that Samba has every supported 
running as an unprivileged user to so it would require launching as root.

Would anyone be opposed to removing this?

-- 
Regards,

Anthony Liguori

[Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Anthony Liguori wrote:
> It looks to be broken.  I don't recall that Samba has every supported
> running as an unprivileged user to so it would require launching as root.

It works perfectly. I even have a patch pending that fixes the zombie
issue it causes (more precisely, slirp missed that).

> 
> Would anyone be opposed to removing this?
> 

No reason to do so IMHO. It's very simple to use, much simpler than
having to configure a full samba server on the host, which would include
user/password management.

Jan


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[Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Jan Kiszka wrote:
> Anthony Liguori wrote:
>> It looks to be broken.  I don't recall that Samba has every supported
>> running as an unprivileged user to so it would require launching as root.
> 
> It works perfectly. I even have a patch pending that fixes the zombie
> issue it causes (more precisely, slirp missed that).
> 
>> Would anyone be opposed to removing this?
>>
> 
> No reason to do so IMHO. It's very simple to use, much simpler than
> having to configure a full samba server on the host, which would include
> user/password management.
> 
> Jan
> 

BTW, I'm sitting on a large rework of all the slirp-related command line
options + a fully-configurable slirp (not yet multi-instance, but that
may come as well). Is your question motivated by some slirp-affecting
work, or just cleanup considerations?

Jan


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Re: [Qemu-devel] Re: Does anyone actually use -smb

[Anthony Liguori]

Jan Kiszka wrote:
> Anthony Liguori wrote:
>   
>> It looks to be broken.  I don't recall that Samba has every supported
>> running as an unprivileged user to so it would require launching as root.
>>     
>
> It works perfectly. I even have a patch pending that fixes the zombie
> issue it causes (more precisely, slirp missed that).
>
>   
>> Would anyone be opposed to removing this?
>>
>>     
>
> No reason to do so IMHO. It's very simple to use, much simpler than
> having to configure a full samba server on the host, which would include
> user/password management.
>   

But you have to run qemu as root, and you can only use -smb with one 
guest at a time?  Is that correct?

Regards,

Anthony Liguori

> Jan
>
>   

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Anthony Liguori wrote:
> Jan Kiszka wrote:
>> Anthony Liguori wrote:
>>  
>>> It looks to be broken.  I don't recall that Samba has every supported
>>> running as an unprivileged user to so it would require launching as
>>> root.
>>>     
>>
>> It works perfectly. I even have a patch pending that fixes the zombie
>> issue it causes (more precisely, slirp missed that).
>>
>>  
>>> Would anyone be opposed to removing this?
>>>
>>>     
>>
>> No reason to do so IMHO. It's very simple to use, much simpler than
>> having to configure a full samba server on the host, which would include
>> user/password management.
>>   
> 
> But you have to run qemu as root, and you can only use -smb with one
> guest at a time?  Is that correct?

Nope, I'm running it as dumb user. I haven't tried multiple qemu
instances, wait... works as well.

Jan


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Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jamie Lokier]

Jan Kiszka wrote:
> Anthony Liguori wrote:
> > It looks to be broken.  I don't recall that Samba has every supported
> > running as an unprivileged user to so it would require launching as root.
> 
> It works perfectly. I even have a patch pending that fixes the zombie
> issue it causes (more precisely, slirp missed that).

I've been unable to use it for a year or so due to Samba having
hard-coded directory paths, pointing into /var/lib/samba, which cannot
be overridden in the config file smb.conf.

(I forget which files were hard-coded, or which distro I hit that on.
Either CentOS, Debian or Ubuntu.  Files were something like
/var/lib/samba/{locking,connections}.tdb, perhaps?)

Because of those paths, non-root wasn't possible and running it as
root caused it to try to clobber some files which interfered with a
non-QEMU ("native") Samba running on the same machine for normal file
service.

I guess if you have a private build of Samba you can avoid this
problem, but even then I'm wondering how you ensure different Samba
instances don't interfere with each other, as there is nowhere in
smb.conf to specify an alternate location for those files normally in
/var/lib/samba.

Jan, do you do anything special for -smb or does it just work?  What
distro and distro version are you using?

Thanks,
-- Jamie

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Jamie Lokier wrote:
> Jan Kiszka wrote:
>> Anthony Liguori wrote:
>>> It looks to be broken.  I don't recall that Samba has every supported
>>> running as an unprivileged user to so it would require launching as root.
>> It works perfectly. I even have a patch pending that fixes the zombie
>> issue it causes (more precisely, slirp missed that).
> 
> I've been unable to use it for a year or so due to Samba having
> hard-coded directory paths, pointing into /var/lib/samba, which cannot
> be overridden in the config file smb.conf.
> 
> (I forget which files were hard-coded, or which distro I hit that on.
> Either CentOS, Debian or Ubuntu.  Files were something like
> /var/lib/samba/{locking,connections}.tdb, perhaps?)
> 
> Because of those paths, non-root wasn't possible and running it as
> root caused it to try to clobber some files which interfered with a
> non-QEMU ("native") Samba running on the same machine for normal file
> service.

I ran strace -e open and only caught this:

[pid 28902] open("/var/log/samba/log.smbd", O_WRONLY|O_CREAT|O_APPEND,
0644) = -1 EACCES (Permission denied)

But that would only be a problem if I ran qemu as root. Hmm, wait, I can
fix it by specifying the file like this:

log file=/tmp/qemu-smb.28902/log.%m

Will write a patch for qemu.

> 
> I guess if you have a private build of Samba you can avoid this
> problem, but even then I'm wondering how you ensure different Samba
> instances don't interfere with each other, as there is nowhere in
> smb.conf to specify an alternate location for those files normally in
> /var/lib/samba.
> 
> Jan, do you do anything special for -smb or does it just work?  What
> distro and distro version are you using?

OpenSUSE 11.0 with samba-3.2.4-4.3 and 11.1 with samba-3.2.7-11.2.1.

Maybe you should file a bug at your distro if its version doesn't behave
according to its docs.

Jan


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[Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Jan Kiszka wrote:
> Jamie Lokier wrote:
>> Jan Kiszka wrote:
>>> Anthony Liguori wrote:
>>>> It looks to be broken.  I don't recall that Samba has every supported
>>>> running as an unprivileged user to so it would require launching as root.
>>> It works perfectly. I even have a patch pending that fixes the zombie
>>> issue it causes (more precisely, slirp missed that).
>> I've been unable to use it for a year or so due to Samba having
>> hard-coded directory paths, pointing into /var/lib/samba, which cannot
>> be overridden in the config file smb.conf.
>>
>> (I forget which files were hard-coded, or which distro I hit that on.
>> Either CentOS, Debian or Ubuntu.  Files were something like
>> /var/lib/samba/{locking,connections}.tdb, perhaps?)
>>
>> Because of those paths, non-root wasn't possible and running it as
>> root caused it to try to clobber some files which interfered with a
>> non-QEMU ("native") Samba running on the same machine for normal file
>> service.
> 
> I ran strace -e open and only caught this:
> 
> [pid 28902] open("/var/log/samba/log.smbd", O_WRONLY|O_CREAT|O_APPEND,
> 0644) = -1 EACCES (Permission denied)
> 
> But that would only be a problem if I ran qemu as root. Hmm, wait, I can
> fix it by specifying the file like this:
> 
> log file=/tmp/qemu-smb.28902/log.%m

Nope, this makes no difference. smbd still starts with accessing
/var/log/samba/log.smbd, writes a few lines into it (if it has access
permissions), then parses smb.conf, and finally switches over to the
specified log file. But that's a non-issue for the typical use case of
-smb: unprivileged qemu.

Jan


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Re: [Qemu-devel] Re: Does anyone actually use -smb

[Alexey Eremenko]

Well, I use Samba from time to time.

But I found out that it not always works.
I used KVM-85, while -smb parameter works fine on my Fedora 7 machine
it totally fails on my Fedora 10 machine.

Guest is Windows XP.

I dunno why, it may be version of samba on Host, or anything else.
-- 
-Alexey Eromenko "Technologov"

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jamie Lokier]

Jan Kiszka wrote:
> OpenSUSE 11.0 with samba-3.2.4-4.3 and 11.1 with samba-3.2.7-11.2.1.
> 
> Maybe you should file a bug at your distro if its version doesn't behave
> according to its docs.

But it does behave according to its docs.

The Samba docs "man smbd" list a lot of files in /var/lib/samba, for
which there is no smb.conf option to change the path.

I've just looked at RHEL 4.6 (ancient - samba-3.0.25b) and Ubuntu 9.04
(new - samba-2:3.3.2-1ubuntu3), which I happen to have.

>From "man smbd", does yours not have these?

   Samba stores it´s data in several TDB (Trivial Database) files, usually
   located in /var/lib/samba.

   (*) information persistent across restarts (but not necessarily
   important to backup).

   account_policy.tdb*
       NT account policy settings such as pw expiration, etc...

   brlock.tdb
       byte range locks

   browse.dat
       browse lists

   connections.tdb
       share connections (used to enforce max connections, etc...)

   gencache.tdb
       generic caching db

   group_mapping.tdb*
       group mapping information

   locking.tdb
       share modes & oplocks

   login_cache.tdb*
       bad pw attempts

   messages.tdb
       Samba messaging system

   netsamlogon_cache.tdb*
       cache of user net_info_3 struct from net_samlogon() request (as a
       domain member)

   ntdrivers.tdb*
       installed printer drivers

   ntforms.tdb*
       installed printer forms

   ntprinters.tdb*
       installed printer information

   printing/
       directory containing tdb per print queue of cached lpq output

   registry.tdb
       Windows registry skeleton (connect via regedit.exe)

   sessionid.tdb
       session information (e.g. support for ´utmp = yes´)

   share_info.tdb*
       share acls

   winbindd_cache.tdb
       winbindd´s cache of user lists, etc...

   winbindd_idmap.tdb*
       winbindd´s local idmap db

   wins.dat*
       wins database when ´wins support = yes´

Most of them correspond to features which are disabled for QEMU, but
some aren't.

I'm only talking about this because I've tried to use QEMU "-smb" in
the last year and couldn't get it working.  It looked like I needed to
reconfigure and recompile Samba from source to use it.

-- Jamie

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jan Kiszka]

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Jamie Lokier wrote:
> Jan Kiszka wrote:
>> OpenSUSE 11.0 with samba-3.2.4-4.3 and 11.1 with samba-3.2.7-11.2.1.
>>
>> Maybe you should file a bug at your distro if its version doesn't behave
>> according to its docs.
> 
> But it does behave according to its docs.
> 
> The Samba docs "man smbd" list a lot of files in /var/lib/samba, for
> which there is no smb.conf option to change the path.
> 
> I've just looked at RHEL 4.6 (ancient - samba-3.0.25b) and Ubuntu 9.04
> (new - samba-2:3.3.2-1ubuntu3), which I happen to have.
> 
> From "man smbd", does yours not have these?
> 
>    Samba stores it´s data in several TDB (Trivial Database) files, usually
                                                                     ^^^^^^^
Sounds not like it is necessarily set in stone.

>    located in /var/lib/samba.
> 
>    (*) information persistent across restarts (but not necessarily
>    important to backup).
> 
>    account_policy.tdb*
>        NT account policy settings such as pw expiration, etc...
> 
>    brlock.tdb
>        byte range locks
> 
>    browse.dat
>        browse lists
> 
>    connections.tdb
>        share connections (used to enforce max connections, etc...)
> 
>    gencache.tdb
>        generic caching db
> 
>    group_mapping.tdb*
>        group mapping information
> 
>    locking.tdb
>        share modes & oplocks
> 
>    login_cache.tdb*
>        bad pw attempts
> 
>    messages.tdb
>        Samba messaging system
> 
>    netsamlogon_cache.tdb*
>        cache of user net_info_3 struct from net_samlogon() request (as a
>        domain member)
> 
>    ntdrivers.tdb*
>        installed printer drivers
> 
>    ntforms.tdb*
>        installed printer forms
> 
>    ntprinters.tdb*
>        installed printer information
> 
>    printing/
>        directory containing tdb per print queue of cached lpq output
> 
>    registry.tdb
>        Windows registry skeleton (connect via regedit.exe)
> 
>    sessionid.tdb
>        session information (e.g. support for ´utmp = yes´)
> 
>    share_info.tdb*
>        share acls
> 
>    winbindd_cache.tdb
>        winbindd´s cache of user lists, etc...
> 
>    winbindd_idmap.tdb*
>        winbindd´s local idmap db
> 
>    wins.dat*
>        wins database when ´wins support = yes´

This is how my /tmp/qemu-smb.x folder looks like when running "smbclient
//10.0.2.4/qemu" in the guest:

account_policy.tdb
brlock.tdb
connections.tdb
gencache.tdb
group_mapping.ldb
locking.tdb
log.smbd
messages.tdb
notify.tdb
ntdrivers.tdb
ntforms.tdb
ntprinters.tdb
perfmon
printing
registry.tdb
secrets.tdb
sessionid.tdb
share_info.tdb
smb.conf
smbpasswd

> 
> Most of them correspond to features which are disabled for QEMU, but
> some aren't.
> 
> I'm only talking about this because I've tried to use QEMU "-smb" in
> the last year and couldn't get it working.  It looked like I needed to
> reconfigure and recompile Samba from source to use it.

Would be interesting to know if that makes a difference for you.

Jan


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Re: [Qemu-devel] Re: Does anyone actually use -smb

[Avi Kivity]

Jan Kiszka wrote:
>> From "man smbd", does yours not have these?
>>
>>    Samba stores it´s data in several TDB (Trivial Database) files, usually
>>     
>                                                                      ^^^^^^^
> Sounds not like it is necessarily set in stone.
>   

To me it sounds like a build option :)

-- 
error compiling committee.c: too many arguments to function

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Jamie Lokier]

Jan Kiszka wrote:
> Jamie Lokier wrote:
> > Jan Kiszka wrote:
> >> Anthony Liguori wrote:
> >>> It looks to be broken.  I don't recall that Samba has every supported
> >>> running as an unprivileged user to so it would require launching as root.
> >> It works perfectly. I even have a patch pending that fixes the zombie
> >> issue it causes (more precisely, slirp missed that).
> > 
> > I've been unable to use it for a year or so due to Samba having
> > hard-coded directory paths, pointing into /var/lib/samba, which cannot
> > be overridden in the config file smb.conf.
> > 
> > (I forget which files were hard-coded, or which distro I hit that on.
> > Either CentOS, Debian or Ubuntu.  Files were something like
> > /var/lib/samba/{locking,connections}.tdb, perhaps?)
> > 
> > Because of those paths, non-root wasn't possible and running it as
> > root caused it to try to clobber some files which interfered with a
> > non-QEMU ("native") Samba running on the same machine for normal file
> > service.
> 
> I ran strace -e open and only caught this:
> 
> [pid 28902] open("/var/log/samba/log.smbd", O_WRONLY|O_CREAT|O_APPEND,
> 0644) = -1 EACCES (Permission denied)

Is that just starting Samba, or accessing a share from a Windows guest
and doing some file accesses with locking?

-- Jamie

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Anthony Liguori]

Jamie Lokier wrote:
> Jan Kiszka wrote:
>   
>> Anthony Liguori wrote:
>>     
>>> It looks to be broken.  I don't recall that Samba has every supported
>>> running as an unprivileged user to so it would require launching as root.
>>>       
>> It works perfectly. I even have a patch pending that fixes the zombie
>> issue it causes (more precisely, slirp missed that).
>>     
>
> I've been unable to use it for a year or so due to Samba having
> hard-coded directory paths, pointing into /var/lib/samba, which cannot
> be overridden in the config file smb.conf.
>   

Yes, this has been my experience too.  I just assumed this was upstream 
behavior.

-- 
Regards,

Anthony Liguori

Re: [Qemu-devel] Re: Does anyone actually use -smb

[Avi Kivity]

Anthony Liguori wrote:
>> I've been unable to use it for a year or so due to Samba having
>> hard-coded directory paths, pointing into /var/lib/samba, which cannot
>> be overridden in the config file smb.conf.
>>   
>
> Yes, this has been my experience too.  I just assumed this was 
> upstream behavior.
>

I think we should regard this as a regression in samba, and submit a bug 
report or a patch.  It doesn't make sense for a program like samba only 
to work as a single instance.

-- 
error compiling committee.c: too many arguments to function