samba - Nov 2015 - widelinks_warning - but unix extensions *are* off

Sorry for the delay and thanks for your pointers.

"allow insecure wide links" does not change the behaviour, tried that
before. Which is strange, if you look at the code.

On the other hand it is clearly not a static misconfiguration, otherwise I would
be able to reproduce it.

About half of the time, we get a PANIC about 5 to 10 minutes after these strange
widelinks_warnings appear in the logfile. It just happened again:

[2015/11/02 15:26:02.611300,  0]
../source3/param/loadparm.c:4306(widelinks_warning)
  Share 'data' has wide links and unix extensions enabled. These
parameters are incompatible. Wide links will be disabled for this share.
[2015/11/02 15:26:02.706290,  0]
../source3/param/loadparm.c:4306(widelinks_warning)
  Share 'group' has wide links and unix extensions enabled. These
parameters are incompatible. Wide links will be disabled for this share.
[2015/11/02 15:26:03.010964,  0]
../source3/param/loadparm.c:4306(widelinks_warning)
  Share 'web' has wide links and unix extensions enabled. These
parameters are incompatible. Wide links will be disabled for this share.
[2015/11/02 15:33:27.613228,  0]
../source3/lib/popt_common.c:68(popt_s3_talloc_log_fn)
  talloc: access after free error - first free may be at <E0>^A
[2015/11/02 15:33:27.616936,  0]
../source3/lib/popt_common.c:68(popt_s3_talloc_log_fn)
  Bad talloc magic value - access after free
[2015/11/02 15:33:27.618304,  0] ../source3/lib/util.c:788(smb_panic_s3)
  PANIC (pid 12270): Bad talloc magic value - access after free
[2015/11/02 15:33:27.636001,  0] ../source3/lib/util.c:899(log_stack_trace)
  BACKTRACE: 43 stack frames:
   #0 /usr/local/samba-4.2.5/lib/libsmbconf.so.0'log_stack_trace+0x2b
[0xfd9e18d8]
   #1 /usr/local/samba-4.2.5/lib/libsmbconf.so.0'smb_panic_s3+0x80
[0xfd9e173f]
   #2 /usr/local/samba-4.2.5/lib/libsamba-util.so.0.0.1'smb_panic+0x2a
[0xfe758fc6]
   #3
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'talloc_abort+0x44
[0xfe6a2647]
   #4
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'talloc_abort_access_after_free+0x20
[0xfe6a26f0]
   #5
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'talloc_chunk_from_ptr+0x63
[0xfe6a277f]
   #6
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free+0x35
[0xfe6a43d1]
   #7
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'fsp_free+0x218
[0xfe2c1460]
   #8
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'file_free+0x17e
[0xfe2c164f]
   #9
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbXsrv_open_close+0x668
[0xfe3a93a3]
   #10
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbXsrv_open_destructor+0x34
[0xfe3a8142]
   #11
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free_internal+0x154
[0xfe6a3352]
   #12
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free_children_internal+0x76
[0xfe6a411c]
   #13
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free_internal+0x2ae
[0xfe6a34ac]
   #14
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free_children_internal+0x76
[0xfe6a411c]
   #15
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free_internal+0x2ae
[0xfe6a34ac]
   #16
/usr/local/samba-4.2.5/lib/private/libtalloc.so.2.1.2'_talloc_free+0xe5
[0xfe6a4481]
   #17
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'exit_server_common+0x59d
[0xfe3aae00]
   #18 /usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'0x1aaf32
[0xfe3aaf32]
   #19
/usr/local/samba-4.2.5/lib/private/libsmbd-shim-samba4.so'exit_server_cleanly+0x2a
[0xfd6c0f51]
   #20
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'dup_smb2_vec4+0x0
[0xfe37860d]
   #21
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_request_create_done+0x81c
[0xfe386826]
   #22
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'_tevent_req_notify_callback+0x5c
[0xfe62606c]
   #23
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_request_pending_queue+0x44
[0xfe378ea2]
   #24
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_request_process_create+0x7e9
[0xfe385f23]
   #25
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_request_dispatch+0xfc1
[0xfe37c55b]
   #26
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_io_handler+0x72f
[0xfe37fe95]
   #27
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_smb2_connection_handler+0x55
[0xfe37ffa8]
   #28 /usr/local/samba-4.2.5/lib/libsmbconf.so.0'run_events_poll+0x483
[0xfd9fdd19]
   #29 /usr/local/samba-4.2.5/lib/libsmbconf.so.0's3_event_loop_once+0x18a
[0xfd9fdfe5]
   #30
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'_tevent_loop_once+0xf3
[0xfe62489f]
   #31
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'tevent_common_loop_wait+0x26
[0xfe624b01]
   #32
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'_tevent_loop_wait+0x1d
[0xfe624bb3]
   #33
/usr/local/samba-4.2.5/lib/private/libsmbd-base-samba4.so'smbd_process+0xc07
[0xfe36375c]
   #34 /usr/local/samba-4.2.5/sbin/smbd'smbd_accept_connection+0x435
[0x805b021]
   #35 /usr/local/samba-4.2.5/lib/libsmbconf.so.0'run_events_poll+0x483
[0xfd9fdd19]
   #36 /usr/local/samba-4.2.5/lib/libsmbconf.so.0's3_event_loop_once+0x18a
[0xfd9fdfe5]
   #37
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'_tevent_loop_once+0xf3
[0xfe62489f]
   #38
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'tevent_common_loop_wait+0x26
[0xfe624b01]
   #39
/usr/local/samba-4.2.5/lib/private/libtevent.so.0.9.25'_tevent_loop_wait+0x1d
[0xfe624bb3]
   #40 /usr/local/samba-4.2.5/sbin/smbd'smbd_parent_loop+0xa5 [0x805be67]
   #41 /usr/local/samba-4.2.5/sbin/smbd'main+0x19e3 [0x805da17]
   #42 /usr/local/samba-4.2.5/sbin/smbd'_start+0x83 [0x8055ec3]
[2015/11/02 15:33:27.662048,  0] ../source3/lib/dumpcore.c:318(dump_core)
  dumping core in /usr/local/samba-4.2.5/var/cores/smbd

Regards, Thomas
> On 30.10.2015, at 12:44, L.P.H. van Belle <belle at bazuin.nl> wrote:
> 
> I suggest you try something like. 
> 
> 
> Global smb.conf options: 
>    unix extensions = No
>    allow insecure wide links = Yes
> 
> Per share smb.conf options: 
> ## and share options niet global used.
>       wide links = yes
>       follow symlinks = yes
> 
> 
> 
>> -----Oorspronkelijk bericht-----
>> Van: samba [mailto:samba-bounces at lists.samba.org] Namens Rowland
Penny
>> Verzonden: vrijdag 30 oktober 2015 11:46
>> Aan: samba at lists.samba.org
>> Onderwerp: Re: [Samba] widelinks_warning - but unix extensions *are*
off
>> 
>> On 30/10/15 10:25, Thomas Werschlein wrote:
>>> 
>>>> On 29 Oct 2015, at 23:22, Jeremy Allison <jra at
samba.org> wrote:
>>>> 
>>>> On Thu, Oct 29, 2015 at 05:27:49PM +0100, Thomas Werschlein
wrote:
>>>>> Hi all
>>>>> 
>>>>> Since we changed our installation from Samba 3.x to 4.x
(currently
>> 4.2.5 on Solaris 11.1), we repeatedly encounter the following
>> 'widelinks_warning', originating from Windows Server 2012 R2
RDS clients:
>>>>> 
>>>>> [2015/10/29 15:50:38.837702,  0]
>> ../source3/param/loadparm.c:4306(widelinks_warning)
>>>>>  Share 'data' has wide links and unix extensions
enabled. These
>> parameters are incompatible. Wide links will be disabled for this
share.
>>>>> [2015/10/29 15:50:38.838518,  0]
>> ../source3/param/loadparm.c:4306(widelinks_warning)
>>>>>  Share 'group' has wide links and unix extensions
enabled. These
>> parameters are incompatible. Wide links will be disabled for this
share.
>>>>> [2015/10/29 15:50:38.839070,  0]
>> ../source3/param/loadparm.c:4306(widelinks_warning)
>>>>>  Share 'web' has wide links and unix extensions
enabled. These
>> parameters are incompatible. Wide links will be disabled for this
share.
>>>>> 
>>>>> The strange thing is: "unix extensions" *are*
actually off. "wide
>> links" are on, since we use them for vfs_shadow_copy2 (but not on
the
>> affected shares):
>>>>> 
>>>>> # testparm -sv 2>/dev/null |egrep 'wide links|unix
extensions'
>>>>>        unix extensions = No
>>>>>        allow insecure wide links = No
>>>>>        wide links = Yes
>>>>> 
>>>>> The affected shares (data, group, web) are distinct from
"working"
>> ones, by the fact that "hide unreadable" is set to
"Yes" on the affected
>> shares only. This is how the affected shares are configured:
>>>>> 
>>>>> [data]
>>>>>        path = /pool1/data
>>>>>        read only = No
>>>>>        acl map full control = No
>>>>>        ea support = Yes
>>>>>        nt acl support = No
>>>>>        hide unreadable = Yes
>>>>>        map archive = No
>>>>>        map readonly = no
>>>>>        store dos attributes = Yes
>>>>>        vfs objects = zfsacl full_audit
>>>>> 
>>>>> Unfortunately, we can't trigger the behaviour. It's
all pretty fuzzy,
>> but maybe someone out there has an idea what's going on?
>>>> That message is coming from here:
>>>> 
>>>> void widelinks_warning(int snum)
>>>> {
>>>>        if (lp_allow_insecure_wide_links()) {
>>>>                return;
>>>>        }
>>>> 
>>>>        if (lp_unix_extensions() && lp_wide_links(snum))
{
>>>>                DEBUG(0,("Share '%s' has wide links
and unix extensions
>> enabled. "
>>>>                        "These parameters are incompatible.
"
>>>>                        "Wide links will be disabled for
this
>> share.\n",
>>>>                         lp_servicename(talloc_tos(), snum) ));
>>>>        }
>>>> }
>>>> 
>>>> so it's pretty simple. Both must be being seen to emit the
message.
>>>> Can you get this reproducible ?
>>> I am aware of the code above. What I don't grasp is: what is
turning on
>> "unix extensions", under what circumstances? I can access all
the affected
>> shares from the same clients without triggering the warning (no
surprise,
>> since "unix extensions" is globally turned off). So no, I am
not able to
>> reproduce it.
>>> 
>>> I increased the log level, but since this is a pretty busy
production
>> system and the warning appears every second day only, it was not
feasible
>> (at least I did not find a way yet). But thanks for your pointer!
>>> 
>>> 
>>> 
>> 
>> Hi , it might help if you posted your entire smb.conf rather than a
>> fragment. If you read the smb.conf manpage, under 'wide links'
there is
>> this:
>> 
>> Due to this problem, this parameter will be automatically disabled
(with
>> a message in the log file) if the unix
>> extensions option is on.
>> 
>> So, for whatever reason, samba seems to think that the unix extensions
>> are on.
>> 
>> Rowland

On 02/11/15 15:09, Thomas Werschlein wrote:

Well he didn't write what I asked for, can you please post your entire 
smb.conf, please do not use testparm, please post as is (although you 
can sanitise any sensitive info)

Rowland

> On 02.11.2015, at 16:25, Rowland Penny <rowlandpenny241155 at
gmail.com> wrote:
> 
> Well he didn't write what I asked for, can you please post your entire
smb.conf, please do not use testparm, please post as is (although you can
sanitise any sensitive info)
Sorry, missed that part. Here we go.
Regards, Thomas

[global]
  available = yes
  smb2 leases = yes
  dbwrap_tdb_mutexes:* = yes

  fruit:resource = xattr
  kerberos method = system keytab

  smb ports = 445

  log level = 0
  log file =/usr/local/samba-4.2.5/var/logs_per_client/log.%m

  max open files = 262144

  realm = D.SOME.ORG.TLD
  workgroup = D
  security = ADS
  disable netbios = yes
  local master = no
  domain master = no

  host msdfs = no

  idmap config * : backend = tdb
  idmap config * : range = 1000000-1999999
  idmap config D : backend  = nss
  idmap config D : range = 1000-999999
  idmap negative cache time = 0

  netbios name = FSRV
  server signing = auto
  create mask = 0644
  server string   hide dot files = yes
  hide files = /Maildir/$RECYCLE.BIN/desktop.ini
  load printers = no
  printing = bsd
  printcap name = /dev/null
  deadtime = 15

  interfaces = 192.168.222.77/32
  bind interfaces only = yes

  unix extensions = no

  map untrusted to domain = yes

  username map script = /usr/local/samba-4.2.5/etc/samba/mapcomputers.sh

  shadow:snapdir = .zfs/snapshot
  shadow:sort = desc
  shadow:localtime = yes
  shadow:format = %Y%m%d%H%M
  wide links = yes

  vfs objects = full_audit
  full_audit:prefix = %u|%I|%m|%S
  full_audit:success = mkdir rename rmdir pwrite
  full_audit:failure = none
  full_audit:facility = LOCAL7
  full_audit:priority = NOTICE

  aio read size = 1
  aio write size =1

[homes]
  path = /pool1/home/%S
  read only = no
  browseable = no
  create mask = 0640
  directory mask = 0750
  ea support = yes
  store dos attributes = yes

  vfs objects = shadow_copy2 fruit streams_xattr zfsacl full_audit
  nt acl support = yes
  inherit acls = no

[group]
  read only = no
  path = /pool1/group
  hide unreadable = yes
  comment = Group spaces of %U
  create mask = 0660
  directory mask = 0770
  force create mode = 0660
  force directory mode = 0770
  ea support = yes
  store dos attributes = yes
  map archive = No
  map hidden = No
  map system = No
  map readonly = No
  vfs objects = fruit streams_xattr zfsacl
  acl map full control = False
  nt acl support = no
  inherit acls = no

[web]
  read only = no
  path = /pool1/web
  hide unreadable = yes
  comment = Web spaces
  create mask = 0664
  directory mask = 0775
  force create mode = 0664
  force directory mode = 0775
  ea support = yes
  store dos attributes = yes
  map archive = No
  map hidden = No
  map system = No
  map readonly = No
  vfs objects = zfsacl full_audit
  acl map full control = False
  nt acl support = no
  inherit acls = no

[data]
  path = /pool1/data
  hide unreadable = yes
  read only = no
  ea support = yes
  store dos attributes = yes
  map archive = No
  map hidden = No
  map system = No
  map readonly = No
  vfs objects = zfsacl full_audit
  acl map full control = False
  nt acl support = no
  inherit acls = no