SMB user is owner of directory but it is using group permission

Question

Rewording:

I have a directory with permission 755, shared using samba. I have a samba user abc:abc which is also the owner of that directory. Windows samba client was denied write to the directory. When I chmod the directory to 775, the windows client is now able to write in it.

From the above, I have the conclusion that directory is checking samba user's group permission even though said user is the owner of the directory. Why is it?

Original details:

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Apologize if I have any typo, I am typing it from air.

drwxr-xr-x abc abc 4096 DirectoryName

I have smb.conf sharing it.

[something] comment = something browseable = yes path = /something/something guest ok = no read only = no create mask = 0775 valid user = abc

On windows 10, I used user abc to access the samba share. I notice that I don't have permission to write to the folder. It is weird to me because abc is the owner of the directory and it should have full access. I changed the permission with chmod 775 and abc can now write so I have the conclusion that it is using the group permission to access instead.

Why is it? I thought owner permission has priority over group. Is this how it works or just how samba handles permission?

Also is directory mask needed in smb.conf? How is it different from the directory permission itself?

Answer 1

If you do not configure directory mask then a default value is used. This value is equivalent to the umask of a process. It affects the permissions of newly created directories.

A new directory has these permissions:

directory mask 000

000

directory mask 755

755

directory mask 777

777

Answer 2

I just experienced these exact symptoms. Centos 8, Samba 4.11.2. Turned out to be a problematic cache. I adapted command lines (as superuser, naturally) found on this Kombitz page for my specific setup as follows:

systemctl stop nmb
systemctl stop smb
net cache flush
cd /var/lib/samba
rm *.tdb
systemctl start nmb
systemctl start smb

After doing this, the problem went away; Samba began correctly applying user permissions instead of the user's group permissions. Reboot wasn't necessary.