Dell Unity, PowerStore: Changing UMASK on SMB Share on Multiprotocol NAS Does Not Change Default Mode Bits for Connected SMB Clients

The UMASK property of an SMB share of a multiprotocol file system was recently changed to a new value.

When the UMASK advanced property of an SMB share of a multiprotocol file system is changed to a new value, connected SMB clients may still assign UNIX mode bits based on the prior UMASK.

Changes to UMASK are reflected in the share configuration immediately. However, the UMASK value established when the session setup is performed determines the operable UMASK. Therefore, any client that does not sever its connection to the share, continues to use the prior UMASK value. When the client disconnects (as verified with svc_cifssupport <NAS SERVER> -audit -full), upon reconnecting the UMASK reflects the updated UMASK and files created by that user show the expected mode bits when viewed from the UNIX or Linux client.

SMB clients must disconnect and reconnect to use the new UMASK value.

Use the svc_cifssupport command to verify a client's current UMASK, or verify that a client is disconnected:

service@alpha-spa spa:~> svc_cifssupport Megatron -audit

Megatron :
|||| AUDIT Ctx=0x00091aea38, ref=2, Fedora6 Client(10.0.1.249) Port=46042/445
||| MEGATRON[PEEPS] on if=1_alpha
||| CurrentDC 0x0007d3a858=PEEPS-DC
||| Proto=NT1, Arch=Win2K, RemBufsz=0x4054, LocBufsz=0xffff, popupMsg=1
||| 0 FNN in FNNlist NbUsr=1 NbCnx=1
||| Uid=0x3f NTcred(0x0008bd5f58 RC=3 NTLMSSP Capa=0x2001) 'PEEPS\administrator'
|| Cnxp(0x0009e6e8e8), Name=mpfs01, cUid=0x3f Tid=0x3f, Ref=1, Aborted=0
| readOnly=0, umask=27, opened files/dirs=0
| types=Global - - - - - - - OCNone
| Absolute path of the share=\mpfs01
||| SMB2 session Id=0x598dc76d00000001, 1 channel(s)
||| Uid=0x1 NTcred(0x0008e9e758 RC=9 KERBEROS Capa=0x800002) 'PEEPS\administrator'
|||| AUDIT Ctx=0x000924d638, ref=2,  Client(10.0.1.250) Port=65083/445
||| MEGATRON[PEEPS] on if=1_alpha
||| CurrentDC 0x0007d3a858=PEEPS-DC
||| Proto=SMB2.10, MaxReadWriteSz=0x800000, MaxTransactSz=0x800000, popupMsg=1
||| SrvCapa=0x7, CltCapa=0x0, SrvSecMode=0x1, CltSecMode=0x1
||| PreAuthIntgAlgo:NONE, EncryptionAlgoId:AES_128_CCM
||| Client GUID=54959e9a-3266-11e7-8171-0050569115ca
||| SMB2 credits: Granted=31, Max=512, AsyncPendind=2, topAsyncPending=2
||| 0 FNN in FNNlist NbUsr=1 NbCnx=1
|| Cnxp(0x0009e6e4e8), Name=mpfs01, cUid=0x1 Tid=0x2, Ref=1, Aborted=0
| readOnly=0, umask=27, opened files/dirs=3
| types=Global - - - - - - - OCNone
| Absolute path of the share=\mpfs01
total smb_streamCtx: 2

The equivalent of running this command on PowerStore as the service user would be the following:

svc_nas_cifssupport --server Megatron --args "-audit -full"

Failing over a NAS server to the peer node or Storage Processor (SP) after changing the UMASK forces all clients to establish a new SMB session.