HI everyone.
I’ve been analyzing a problem with an embedded Linux/FPGA device that in some cases was failing to run properly when using files from a samba share. After some time I’ve found it is related to Samba bug 12783 and setting kernel oplocks on global fix the issue.
But while looking at that I have found a strange behavior I can’t understand. I have guest ok = yes on the share and map to guest = Bad User on global.
If I mount the share with a bad user, everything works OK and I can see the device lock on the file with smbstatus.
But if I mount the samba share with sec=none , the program will throw an error, I think because it wasn’t able to adquire a lock on the file - I don’t see a lock in smbstatus.
In both cases the connection is assigned to nobody, as configured for guest connections. I run samba 4.20.5 on Truenas Scale 24.10 . I sent this same information to the Samba mailing list and the answer was “Oh, yeah, somethings wrong, who knows if in Samba server, client, or Truenas” 
- the output of testparm -s
Load smb config files from /etc/smb4.conf
Loaded services file OK.
Weak crypto is allowed by GnuTLS (e.g. NTLM as a compatibility fallback)
Server role: ROLE_STANDALONE
# Global parameters
[global]
bind interfaces only = Yes
disable spoolss = Yes
dns proxy = No
load printers = No
logging = file
map to guest = Bad User
max log size = 5120
passdb backend = tdbsam:/var/run/samba-cache/private/passdb.tdb
printcap name = /dev/null
registry shares = Yes
server multi channel support = No
server string = TrueNAS Server
winbind request timeout = 2
workgroup = CORUSCANT
idmap config * : range = 90000001 - 100000000
fruit:zero_file_id = False
fruit:nfs_aces = False
idmap config * : backend = tdb
create mask = 0664
directory mask = 0775
kernel oplocks = Yes
(REMOVED INFO FROM SHARES NOT INVOLVED IN THIS)
[descargas]
ea support = No
guest ok = Yes
path = /mnt/NAS/descargas
read only = No
smbd max xattr size = 2097152
vfs objects = streams_xattr shadow_copy_zfs ixnas zfs_core io_uring
tn:vuid =
fruit:time machine max size = 0
fruit:time machine = False
nfs4:chown = True
tn:home = False
tn:path_suffix =
tn:purpose = MULTI_PROTOCOL_NFS
- the audit logs provided by Truenas when I connect with bad user
Logon ID: '0'
Logon Type: 3
Local Address: ipv4:192.168.1.4:445
Remote Address: ipv4:192.168.1.100:55186
Service Description: SMB2
Auth Description: Null
Client Domain: ''
Client Account: badusertest
Workstation: ''
Became Account: Null
Became Domain: Null
Became Sid: Null
Mapped Account: badusertest
Mapped Domain: ''
Netlogon Computer: Null
Netlogon Trust Account: Null
Netlogon Negotiate Flags: '0x00000000'
Netlogon Secure Channel Type: 0
Netlogon Trust Account Sid: Null
Password Type: NTLMv2
Client Policy Access Check: Null
Server Policy Access Check: Null
Vers:
Major: 0
Minor: 1
Result:
Type: NTSTATUS
Value Raw: 3221225572
Value Parsed: NT_STATUS_NO_SUCH_USER
- the smbstatus when connected with bad user
Samba version 4.20.5-truenas
PID Username Group Machine Protocol Version Encryption Signing
----------------------------------------------------------------------------------------------------------------------------------------
193273 nobody nogroup 192.168.1.100 (ipv4:192.168.1.100:55188) SMB3_11 - -
102411 nobody nogroup 192.168.1.10 (ipv4:192.168.1.10:47964) SMB3_11 - -
Service pid Machine Connected at Encryption Signing
---------------------------------------------------------------------------------------------
IPC$ 102411 192.168.1.10 Fri Jan 17 18:53:13 2025 CET - -
descargas 193273 192.168.1.100 Fri Jan 17 21:56:27 2025 CET - -
Carpetas Personales 102411 192.168.1.10 Fri Jan 17 18:53:13 2025 CET - -
IPC$ 193273 192.168.1.100 Fri Jan 17 21:56:27 2025 CET - -
Locked files:
Pid User(ID) DenyMode Access R/W Oplock SharePath Name Time
--------------------------------------------------------------------------------------------------
193273 65534 DENY_NONE 0x12019f RDWR BATCH /mnt/NAS/descargas MiSTer/games/AO486/media/another world/another world.vhd Fri Jan 17 21:58:04 2025
- the audit logs provided by Truenas when I connect with sec=none
Logon ID: '0'
Logon Type: 3
Local Address: ipv4:192.168.1.4:445
Remote Address: ipv4:192.168.1.100:43240
Service Description: SMB2
Auth Description: Null
Client Domain: ''
Client Account: ''
Workstation: ''
Became Account: nobody
Became Domain: TRUENAS
Became Sid: S-1-5-21-2028966449-1147323095-3560797536-501
Mapped Account: ''
Mapped Domain: ''
Netlogon Computer: Null
Netlogon Trust Account: Null
Netlogon Negotiate Flags: '0x00000000'
Netlogon Secure Channel Type: 0
Netlogon Trust Account Sid: Null
Password Type: No-Password
Client Policy Access Check: Null
Server Policy Access Check: Null
Vers:
Major: 0
Minor: 1
Result:
Type: NTSTATUS
Value Raw: 0
Value Parsed: SUCCESS
- the smbstatus when using sec=none
Samba version 4.20.5-truenas
PID Username Group Machine Protocol Version Encryption Signing
----------------------------------------------------------------------------------------------------------------------------------------
102411 nobody nogroup 192.168.1.10 (ipv4:192.168.1.10:47964) SMB3_11 - -
187450 nobody nogroup 192.168.1.100 (ipv4:192.168.1.100:43240) SMB3_11 - -
Service pid Machine Connected at Encryption Signing
---------------------------------------------------------------------------------------------
IPC$ 102411 192.168.1.10 Fri Jan 17 18:53:13 2025 CET - -
IPC$ 187450 192.168.1.100 Fri Jan 17 21:44:41 2025 CET - -
Carpetas Personales 102411 192.168.1.10 Fri Jan 17 18:53:13 2025 CET - -
descargas 187450 192.168.1.100 Fri Jan 17 21:44:41 2025 CET - -
No locked files
Any idea what can be happening?
