Need help with samba "create mask"

Posted on 2011-10-12
Last Modified: 2012-05-12
I have an ubuntu machine running a samba server to share my "/var/www" folder.

The umask for all users on the linux machine is the default, whatever comes out of the box with Ubuntu 11.04 Server Edition.

I need to set it up so that when users create files via the samba share (e.g. if a windows or a mac desktop connect via samba and create a file), that the file has the following permissions:

user:  read+write
group: read+write
other: read

So basically, what I want is new files to look like this:

-rw-rw-r--  1 john        john     0 2011-10-12 17:21 newfile.txt

To accomplish this, I used the "create mask" and "force create mode" parameters in smb.conf:

        path = /var/www
        writeable = yes
;       browseable = yes
        valid users = john, jane
        create mask = 0775
        directory mask = 0775
        force directory mode = 0775
        force create mode = 0775

Obviously my understanding of umasks is not correct, because when I create a file via samba, I get the following permissions:

-rwxr-xr-x  1 john        john     0 2011-10-12 17:18 asdf.txt

Completely wrong. I have execute permissions where I actually wanted "write" permission, and the "other" group has too much permission.

So i tried something different:

        create mask = 0777
        directory mask = 0777
        force directory mode = 0777
        force create mode = 0777

And the result:

-rwxr-xrwx  1 john        john     0 2011-10-12 17:21 asdf.txt

That's weird too - the OTHER permission got set, but not GROUP.

How do I need to modify the masks above so that I get the desired permissions?
Question by:Frosty555
    LVL 4

    Expert Comment

    by:Christopher Raymond Mendoza
    Have you checked the inherit permissions parameter? It might be overriding your masks.
    LVL 31

    Author Comment

    I tried setting "inherit permissions = no", but that didn't make any difference.

    Some progress: I've been able to successfully set the "force user" and "force group" options so now the user and group are always www-data, which effectively solves my problem. I can leave the masks at their default value and it is good enough.

    ... but I'd like to give the experts here a chance at solving my actual question. I'm really curious why these masks aren't working the way I'd like.
    LVL 4

    Expert Comment

    by:Christopher Raymond Mendoza
    Can you post your smb.conf please?
    LVL 31

    Author Comment

    See below:

    # Sample configuration file for the Samba suite for Debian GNU/Linux.
    # This is the main Samba configuration file. You should read the
    # smb.conf(5) manual page in order to understand the options listed
    # here. Samba has a huge number of configurable options most of which
    # are not shown in this example
    # Some options that are often worth tuning have been included as
    # commented-out examples in this file.
    #  - When such options are commented with ";", the proposed setting
    #    differs from the default Samba behaviour
    #  - When commented with "#", the proposed setting is the default
    #    behaviour of Samba but the option is considered important
    #    enough to be mentioned here
    # NOTE: Whenever you modify this file you should run the command
    # "testparm" to check that you have not made any basic syntactic
    # errors.
    # A well-established practice is to name the original file
    # "smb.conf.master" and create the "real" config file with
    # testparm -s smb.conf.master >smb.conf
    # This minimizes the size of the really used smb.conf file
    # which, according to the Samba Team, impacts performance
    # However, use this with caution if your smb.conf file contains nested
    # "include" statements. See Debian bug #483187 for a case
    # where using a master file is not a good idea.

    #======================= Global Settings =======================


    ## Browsing/Identification ###

    # Change this to the workgroup/NT-domain name your Samba server will part of
          workgroup = workgroup

    # server string is the equivalent of the NT Description field
          server string = %h server (Samba, Ubuntu)

    # Windows Internet Name Serving Support Section:
    # WINS Support - Tells the NMBD component of Samba to enable its WINS Server
    #   wins support = no

    # WINS Server - Tells the NMBD components of Samba to be a WINS Client
    # Note: Samba can be either a WINS Server, or a WINS Client, but NOT both
    ;   wins server = w.x.y.z

    # This will prevent nmbd to search for NetBIOS names through DNS.
          dns proxy = no

    # What naming service and in what order should we use to resolve host names
    # to IP addresses
    ;   name resolve order = lmhosts host wins bcast

    #### Networking ####

    # The specific set of interfaces / networks to bind to
    # This can be either the interface name or an IP address/netmask;
    # interface names are normally preferred
    ;   interfaces = eth0

    # Only bind to the named interfaces and/or networks; you must use the
    # 'interfaces' option above to use this.
    # It is recommended that you enable this feature if your Samba machine is
    # not protected by a firewall or is a firewall itself.  However, this
    # option cannot handle dynamic or non-broadcast interfaces correctly.
    ;   bind interfaces only = yes

    #### Debugging/Accounting ####

    # This tells Samba to use a separate log file for each machine
    # that connects
          log file = /var/log/samba/log.%m

    # Cap the size of the individual log files (in KiB).
          max log size = 1000

    # If you want Samba to only log through syslog then set the following
    # parameter to 'yes'.
    #   syslog only = no

    # We want Samba to log a minimum amount of information to syslog. Everything
    # should go to /var/log/samba/log.{smbd,nmbd} instead. If you want to log
    # through syslog you should set the following parameter to something higher.
          syslog = 0

    # Do something sensible when Samba crashes: mail the admin a backtrace
          panic action = /usr/share/samba/panic-action %d

    ####### Authentication #######

    # "security = user" is always a good idea. This will require a Unix account
    # in this server for every user accessing the server. See
    # /usr/share/doc/samba-doc/htmldocs/Samba3-HOWTO/ServerType.html
    # in the samba-doc package for details.
    #   security = user

    # You may wish to use password encryption.  See the section on
    # 'encrypt passwords' in the smb.conf(5) manpage before enabling.
    ;      encrypt passwords = yes

    # If you are using encrypted passwords, Samba will need to know what
    # password database type you are using.  
    ;      passdb backend = tdbsam

          obey pam restrictions = yes

    # This boolean parameter controls whether Samba attempts to sync the Unix
    # password with the SMB password when the encrypted SMB password in the
    # passdb is changed.
          unix password sync = yes

    # For Unix password sync to work on a Debian GNU/Linux system, the following
    # parameters must be set (thanks to Ian Kahan <<> for
    # sending the correct chat script for the passwd program in Debian Sarge).
          passwd program = /usr/bin/passwd %u
          passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .

    # This boolean controls whether PAM will be used for password changes
    # when requested by an SMB client instead of the program listed in
    # 'passwd program'. The default is 'no'.
          pam password change = yes

    # This option controls how unsuccessful authentication attempts are mapped
    # to anonymous connections
          map to guest = bad user

    ########## Domains ###########

    # Is this machine able to authenticate users. Both PDC and BDC
    # must have this setting enabled. If you are the BDC you must
    # change the 'domain master' setting to no
    ;   domain logons = yes
    # The following setting only takes effect if 'domain logons' is set
    # It specifies the location of the user's profile directory
    # from the client point of view)
    # The following required a [profiles] share to be setup on the
    # samba server (see below)
    ;   logon path = \\%N\profiles\%U
    # Another common choice is storing the profile in the user's home directory
    # (this is Samba's default)
    #   logon path = \\%N\%U\profile

    # The following setting only takes effect if 'domain logons' is set
    # It specifies the location of a user's home directory (from the client
    # point of view)
    ;   logon drive = H:
    #   logon home = \\%N\%U

    # The following setting only takes effect if 'domain logons' is set
    # It specifies the script to run during logon. The script must be stored
    # in the [netlogon] share
    # NOTE: Must be store in 'DOS' file format convention
    ;   logon script = logon.cmd

    # This allows Unix users to be created on the domain controller via the SAMR
    # RPC pipe.  The example command creates a user account with a disabled Unix
    # password; please adapt to your needs
    ; add user script = /usr/sbin/adduser --quiet --disabled-password --gecos "" %u

    # This allows machine accounts to be created on the domain controller via the
    # SAMR RPC pipe.  
    # The following assumes a "machines" group exists on the system
    ; add machine script  = /usr/sbin/useradd -g machines -c "%u machine account" -d /var/lib/samba -s /bin/false %u

    # This allows Unix groups to be created on the domain controller via the SAMR
    # RPC pipe.  
    ; add group script = /usr/sbin/addgroup --force-badname %g

    ########## Printing ##########

    # If you want to automatically load your printer list rather
    # than setting them up individually then you'll need this
    #   load printers = yes

    # lpr(ng) printing. You may wish to override the location of the
    # printcap file
    ;   printing = bsd
    ;   printcap name = /etc/printcap

    # CUPS printing.  See also the cupsaddsmb(8) manpage in the
    # cupsys-client package.
    ;      printing = cups
    ;   printcap name = cups

    ############ Misc ############

    # Using the following line enables you to customise your configuration
    # on a per machine basis. The %m gets replaced with the netbios name
    # of the machine that is connecting
    ;   include = /home/samba/etc/smb.conf.%m

    # Most people will find that this option gives better performance.
    # See smb.conf(5) and /usr/share/doc/samba-doc/htmldocs/Samba3-HOWTO/speed.html
    # for details
    # You may want to add the following on a Linux system:
    #         SO_RCVBUF=8192 SO_SNDBUF=8192
    #   socket options = TCP_NODELAY

    # The following parameter is useful only if you have the linpopup package
    # installed. The samba maintainer and the linpopup maintainer are
    # working to ease installation and configuration of linpopup and samba.
    ;   message command = /bin/sh -c '/usr/bin/linpopup "%f" "%m" %s; rm %s' &

    # Domain Master specifies Samba to be the Domain Master Browser. If this
    # machine will be configured as a BDC (a secondary logon server), you
    # must set this to 'no'; otherwise, the default behavior is recommended.
    #   domain master = auto

    # Some defaults for winbind (make sure you're not using the ranges
    # for something else.)
    ;   idmap uid = 10000-20000
    ;   idmap gid = 10000-20000
    ;   template shell = /bin/bash

    # The following was the default behaviour in sarge,
    # but samba upstream reverted the default because it might induce
    # performance issues in large organizations.
    # See Debian bug #368251 for some of the consequences of *not*
    # having this setting and smb.conf(5) for details.
    ;   winbind enum groups = yes
    ;   winbind enum users = yes

    # Setup usershare options to enable non-root users to share folders
    # with the net usershare command.

    # Maximum number of usershare. 0 (default) means that usershare is disabled.
    ;      usershare max shares = 100

    # Allow users who've been granted usershare privileges to create
    # public shares, not just authenticated ones
          usershare allow guests = yes
          username map = /etc/samba/smbusers
          security = user
    ;      guest ok = no
    ;      guest account = nobody

    #======================= Share Definitions =======================

    # Un-comment the following (and tweak the other settings below to suit)
    # to enable the default home directory shares. This will share each
    # user's home director as \\server\username
    ;   comment = Home Directories
    ;   browseable = no

    # By default, the home directories are exported read-only. Change the
    # next parameter to 'no' if you want to be able to write to them.
    ;   read only = yes

    # File creation mask is set to 0700 for security reasons. If you want to
    # create files with group=rw permissions, set next parameter to 0775.
    ;   create mask = 0700

    # Directory creation mask is set to 0700 for security reasons. If you want to
    # create dirs. with group=rw permissions, set next parameter to 0775.
    ;   directory mask = 0700

    # By default, \\server\username shares can be connected to by anyone
    # with access to the samba server. Un-comment the following parameter
    # to make sure that only "username" can connect to \\server\username
    # The following parameter makes sure that only "username" can connect
    # This might need tweaking when using external authentication schemes
    ;   valid users = %S

    # Un-comment the following and create the netlogon directory for Domain Logons
    # (you need to configure Samba to act as a domain controller too.)
    ;   comment = Network Logon Service
    ;   path = /home/samba/netlogon
    ;   guest ok = yes
    ;   read only = yes

    # Un-comment the following and create the profiles directory to store
    # users profiles (see the "logon path" option above)
    # (you need to configure Samba to act as a domain controller too.)
    # The path below should be writable by all users so that their
    # profile directory may be created the first time they log on
    ;   comment = Users profiles
    ;   path = /home/samba/profiles
    ;   guest ok = no
    ;   browseable = no
    ;   create mask = 0600
    ;   directory mask = 0700

          comment = All Printers
          browseable = no
          path = /var/spool/samba
          printable = yes
    ;      guest ok = no
    ;      read only = yes
          create mask = 0700

    # Windows clients look for this share name as a source of downloadable
    # printer drivers
          comment = Printer Drivers
          path = /var/lib/samba/printers
    ;      browseable = yes
    ;      read only = yes
    ;      guest ok = no
    # Uncomment to allow remote administration of Windows print drivers.
    # You may need to replace 'lpadmin' with the name of the group your
    # admin users are members of.
    # Please note that you also need to set appropriate Unix permissions
    # to the drivers directory for these users to have write rights in it
    ;   write list = root, @lpadmin

    # A sample share for sharing your CD-ROM with others.
    ;   comment = Samba server's CD-ROM
    ;   read only = yes
    ;   locking = no
    ;   path = /cdrom
    ;   guest ok = yes

    # The next two parameters show how to auto-mount a CD-ROM when the
    #      cdrom share is accesed. For this to work /etc/fstab must contain
    #      an entry like this:
    #       /dev/scd0   /cdrom  iso9660 defaults,noauto,ro,user   0 0
    # The CD-ROM gets unmounted automatically after the connection to the
    # If you don't want to use auto-mounting/unmounting make sure the CD
    #      is mounted on /cdrom
    ;   preexec = /bin/mount /cdrom
    ;   postexec = /bin/umount /cdrom

          path = /Backups/backups
    ;      writeable = No
    ;      browseable = yes
          valid users = john

          path = /Backups/oldbackups
    ;      writeable = No
    ;      browseable = yes
          valid users = john

          path = /Files
          writeable = yes
    ;      browseable = yes
          guest ok = yes
          valid users = john jane
          force user = nobody
          force group = nogroup
          inherit permissions = no

          path = /slush
          writeable = yes
    ;      browseable = yes
          valid users = john
          force user = nobody
          force group = nogroup
          inherit permissions = no

          path = /var/www
          writeable = yes
    ;      browseable = yes
          valid users = john, jane
          force user = www-data
          force group = www-data
          inherit permissions = no
            create mask = 0775
            directory mask = 0775
            force directory mode = 0775
            force create mode = 0775

          path = /var/ftp
          writeable = yes
    ;      browseable = yes
          valid users = john, jane
          force user = nobody
          force group = nogroup
          inherit permissions = no
    LVL 4

    Expert Comment

    by:Christopher Raymond Mendoza
    Maybe this would work:

        force directory security mode = 777

    Checked our config and remembered that we have not been using samba's masks and modes for a long time now. We have been using inherit permissions  since it is less tedious to setup and maintain, as long as the permissions of share itself is properly defined of course.
    LVL 31

    Author Comment

    Haven't had a chance to check this yet but I will this weekend - thanks for your patience
    LVL 31

    Accepted Solution

    My solution in the end was to stick with what I had originally:

    As an example, for my [www] directory which works best if all new files created in the directory have the www-data username and group:

            path = /var/www
            writeable = yes
    ;       browseable = yes
            valid users = john, jane
            force user = www-data
            force group = www-data
    ;       inherit permissions = no
    LVL 31

    Author Closing Comment

    Ended up using my own solution

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