RHEL 7 and Samba Permissions in Windows

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I can access my RHEL 7 server just fine from my Windows machine. I can create/edit/delete with no problems. One thing I can't do is change the file attributes like the read-only flag.

A file is owned by root and the group for the file is also root.
Owner and group have rwx on the file.
A windows user (let's call it winuser) can do anything to this file except change the read-only attribute.
I have a "winuser" user created on the RHEL server and it has root as its primary group.

The only way I seem to be able to modify the file attributes is to make winuser the owner of the file. Any ideas why?
Even if I change the group for the file to winuser, it still does not allow the attributes to be changed from Windows.

I'm thinking maybe this is a Samba configuration issue? Like I said, from the Windows machine I can do everything else: create/delete/edit. I just can't change the attributes. Am I out of luck here? Is this just not allowed unless the user is the owner?

Thanks.

Responses

Neil - Please provide a little more information about your configuration.

  • SAMBA version.
  • SAMBA share configuration.
  • View a sample file's permissions, from both the Microsoft Windows side and the RHEL 7 side.
-rwxrwxr--. 1 root root 6455 Sep 30 17:59 test.jsp

samba-4.1.1-37.el7_0.x86_64

# This is the main Samba configuration file. For detailed information about the
# options listed here, refer to the smb.conf(5) manual page. Samba has a huge
# number of configurable options, most of which are not shown in this example.
#
# The Official Samba 3.2.x HOWTO and Reference Guide contains step-by-step
# guides for installing, configuring, and using Samba:
# http://www.samba.org/samba/docs/Samba-HOWTO-Collection.pdf
#
# The Samba-3 by Example guide has working examples for smb.conf. This guide is
# generated daily: http://www.samba.org/samba/docs/Samba-Guide.pdf
#
# In this file, lines starting with a semicolon (;) or a hash (#) are
# comments and are ignored. This file uses hashes to denote commentary and
# semicolons for parts of the file you may wish to configure.
#
# Note: Run the "testparm" command after modifying this file to check for basic
# syntax errors.
#
#---------------
# Security-Enhanced Linux (SELinux) Notes:
#
# Turn the samba_domain_controller Boolean on to allow Samba to use the useradd
# and groupadd family of binaries. Run the following command as the root user to
# turn this Boolean on:
# setsebool -P samba_domain_controller on
#
# Turn the samba_enable_home_dirs Boolean on if you want to share home
# directories via Samba. Run the following command as the root user to turn this
# Boolean on:
# setsebool -P samba_enable_home_dirs on
#
# If you create a new directory, such as a new top-level directory, label it
# with samba_share_t so that SELinux allows Samba to read and write to it. Do
# not label system directories, such as /etc/ and /home/, with samba_share_t, as
# such directories should already have an SELinux label.
#
# Run the "ls -ldZ /path/to/directory" command to view the current SELinux
# label for a given directory.
#
# Set SELinux labels only on files and directories you have created. Use the
# chcon command to temporarily change a label:
# chcon -t samba_share_t /path/to/directory
#
# Changes made via chcon are lost when the file system is relabeled or commands
# such as restorecon are run.
#
# Use the samba_export_all_ro or samba_export_all_rw Boolean to share system
# directories. To share such directories and only allow read-only permissions:
# setsebool -P samba_export_all_ro on
# To share such directories and allow read and write permissions:
# setsebool -P samba_export_all_rw on
#
# To run scripts (preexec/root prexec/print command/...), copy them to the
# /var/lib/samba/scripts/ directory so that SELinux will allow smbd to run them.
# Note that if you move the scripts to /var/lib/samba/scripts/, they retain
# their existing SELinux labels, which may be labels that SELinux does not allow
# smbd to run. Copying the scripts will result in the correct SELinux labels.
# Run the "restorecon -R -v /var/lib/samba/scripts" command as the root user to
# apply the correct SELinux labels to these files.
#
#--------------
#
#======================= Global Settings =====================================

[global]

# ----------------------- Network-Related Options -------------------------
#
# workgroup = the Windows NT domain name or workgroup name, for example, MYGROUP.
#
# server string = the equivalent of the Windows NT Description field.
#
# netbios name = used to specify a server name that is not tied to the hostname.
#
# interfaces = used to configure Samba to listen on multiple network interfaces.
# If you have multiple interfaces, you can use the "interfaces =" option to
# configure which of those interfaces Samba listens on. Never omit the localhost
# interface (lo).
#
# hosts allow = the hosts allowed to connect. This option can also be used on a
# per-share basis.
#
# hosts deny = the hosts not allowed to connect. This option can also be used on
# a per-share basis.
#
# max protocol = used to define the supported protocol. The default is NT1. You
# can set it to SMB2 if you want experimental SMB2 support.
#
    workgroup = FGIC
    server string = interdevnyc.fgic.com
#username map = /etc/samba/smbusers

    netbios name = interdevnyc

;   interfaces = lo eth0 192.168.12.2/24 192.168.13.2/24
    hosts allow = 127. 10.131.

;   max protocol = SMB2

# --------------------------- Logging Options -----------------------------
#
# log file = specify where log files are written to and how they are split.
#
# max log size = specify the maximum size log files are allowed to reach. Log
# files are rotated when they reach the size specified with "max log size".
#

    # log files split per-machine:
    log file = /var/log/samba/log.%m
    # maximum size of 50KB per log file, then rotate:
    max log size = 50

# ----------------------- Standalone Server Options ------------------------
#
# security = the mode Samba runs in. This can be set to user, share
# (deprecated), or server (deprecated).
#
# passdb backend = the backend used to store user information in. New
# installations should use either tdbsam or ldapsam. No additional configuration
# is required for tdbsam. The "smbpasswd" utility is available for backwards
# compatibility.
#

;   security = user
;   passdb backend = tdbsam


# ----------------------- Domain Members Options ------------------------
#
# security = must be set to domain or ads.
#
# passdb backend = the backend used to store user information in. New
# installations should use either tdbsam or ldapsam. No additional configuration
# is required for tdbsam. The "smbpasswd" utility is available for backwards
# compatibility.
#
# realm = only use the realm option when the "security = ads" option is set.
# The realm option specifies the Active Directory realm the host is a part of.
#
# password server = only use this option when the "security = server"
# option is set, or if you cannot use DNS to locate a Domain Controller. The
# argument list can include My_PDC_Name, [My_BDC_Name], and [My_Next_BDC_Name]:
#
# password server = My_PDC_Name [My_BDC_Name] [My_Next_BDC_Name]
#
# Use "password server = *" to automatically locate Domain Controllers.

;   security = domain
;   passdb backend = tdbsam
;   realm = MY_REALM

;   password server = dc1nyc dc1nj

# ----------------------- Domain Controller Options ------------------------
#
# security = must be set to user for domain controllers.
#
# passdb backend = the backend used to store user information in. New
# installations should use either tdbsam or ldapsam. No additional configuration
# is required for tdbsam. The "smbpasswd" utility is available for backwards
# compatibility.
#
# domain master = specifies Samba to be the Domain Master Browser, allowing
# Samba to collate browse lists between subnets. Do not use the "domain master"
# option if you already have a Windows NT domain controller performing this task.
#
# domain logons = allows Samba to provide a network logon service for Windows
# workstations.
#
# logon script = specifies a script to run at login time on the client. These
# scripts must be provided in a share named NETLOGON.
#
# logon path = specifies (with a UNC path) where user profiles are stored.
#
#
;   security = user
;   passdb backend = tdbsam

;   domain master = yes
;   domain logons = yes

    # the following login script name is determined by the machine name
    # (%m):
;   logon script = %m.bat
    # the following login script name is determined by the UNIX user used:
;   logon script = %u.bat
;   logon path = \\%L\Profiles\%u
    # use an empty path to disable profile support:
;   logon path =

    # various scripts can be used on a domain controller or a stand-alone
    # machine to add or delete corresponding UNIX accounts:

;   add user script = /usr/sbin/useradd "%u" -n -g users
;   add group script = /usr/sbin/groupadd "%g"
;   add machine script = /usr/sbin/useradd -n -c "Workstation (%u)" -M -d /nohome -s /bin/false "%u"
;   delete user script = /usr/sbin/userdel "%u"
;   delete user from group script = /usr/sbin/userdel "%u" "%g"
;   delete group script = /usr/sbin/groupdel "%g"


# ----------------------- Browser Control Options ----------------------------
#
# local master = when set to no, Samba does not become the master browser on
# your network. When set to yes, normal election rules apply.
#
# os level = determines the precedence the server has in master browser
# elections. The default value should be reasonable.
#
# preferred master = when set to yes, Samba forces a local browser election at
# start up (and gives itself a slightly higher chance of winning the election).
#
;   local master = no
;   os level = 33
;   preferred master = yes

#----------------------------- Name Resolution -------------------------------
#
# This section details the support for the Windows Internet Name Service (WINS).
#
# Note: Samba can be either a WINS server or a WINS client, but not both.
#
# wins support = when set to yes, the NMBD component of Samba enables its WINS
# server.
#
# wins server = tells the NMBD component of Samba to be a WINS client.
#
# wins proxy = when set to yes, Samba answers name resolution queries on behalf
# of a non WINS capable client. For this to work, there must be at least one
# WINS server on the network. The default is no.
#
# dns proxy = when set to yes, Samba attempts to resolve NetBIOS names via DNS
# nslookups.

;   wins support = yes
;   wins server = w.x.y.z
;   wins proxy = yes

;   dns proxy = yes

# --------------------------- Printing Options -----------------------------
#
# The options in this section allow you to configure a non-default printing
# system.
#
# load printers = when set you yes, the list of printers is automatically
# loaded, rather than setting them up individually.
#
# cups options = allows you to pass options to the CUPS library. Setting this
# option to raw, for example, allows you to use drivers on your Windows clients.
#
# printcap name = used to specify an alternative printcap file.
#

    load printers = yes
    cups options = raw

;   printcap name = /etc/printcap
    # obtain a list of printers automatically on UNIX System V systems:
;   printcap name = lpstat
;   printing = cups

# --------------------------- File System Options ---------------------------
#
# The options in this section can be un-commented if the file system supports
# extended attributes, and those attributes are enabled (usually via the
# "user_xattr" mount option). These options allow the administrator to specify
# that DOS attributes are stored in extended attributes and also make sure that
# Samba does not change the permission bits.
#
# Note: These options can be used on a per-share basis. Setting them globally
# (in the [global] section) makes them the default for all shares.

;   map archive = no
;   map hidden = no
;   map read only = no
;   map system = no
;   store dos attributes = yes


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

[homes]
    comment = Home Directories
    browseable = no
    writable = yes
;   valid users = %S
;   valid users = MYDOMAIN\%S

[printers]
    comment = All Printers
    path = /var/spool/samba
    browseable = no
    guest ok = no
    writable = no
    printable = yes

# Un-comment the following and create the netlogon directory for Domain Logons:
;   [netlogon]
;   comment = Network Logon Service
;   path = /var/lib/samba/netlogon
;   guest ok = yes
;   writable = no
;   share modes = no

# Un-comment the following to provide a specific roving profile share.
# The default is to use the user's home directory:
;   [Profiles]
;   path = /var/lib/samba/profiles
;   browseable = no
;   guest ok = yes

# A publicly accessible directory that is read only, except for users in the
# "staff" group (which have write permissions):
;   [public]
;   comment = Public Stuff
;   path = /home/samba
;   public = yes
;   writable = yes
;   printable = no
;   write list = +staff

I tried to attach an image of the permissions in windows but it will not show up here. So I will describe them:

root (Unix User\root)
   Read & Execute       Allow
   Read                 Allow
   Write                Allow
   Special Permissions  Allow

root (Unix Group\root)
   Read & Execute       Allow
   Read                 Allow
   Write                Allow
   Special Permissions  Allow

FYI .... I figured out how to insert the image into my original post above.

Neil - Thank you for providing that information.

On a general note, I don't think you should be using the 'root' user or group to secure files and folders intended for use by "general" users. The "root" user has special significance in Unix-like operating systems, as you probably know.

In this case I suggest you:
1. Create a new group for the "winuser" user, for the purposes of testing this scenario.
2. Grant ownership of the file to the new group (created in step 1).
3. Test to see if the "winuser" can modify the attributes of the file.
4. Have the "winuser" create a new file and test that user's access to the file (including ability to change permissions).

I would recommend you review the information contained at [1]. The book's revision is quite old but I believe this information is still accurate.

[1] http://oreilly.com/openbook/samba/book/ch05_03.html

But I already told you that being the owner works. That is not what I'm trying to achieve. I want to have the members of the group for the file be able to change permissions. The group is root and the primary group for my account (winuser) is root. So I should be able to change permissions, correct? But I can't.

Neil,

Only the owner and root can change the permissions of a file (in RH), not group members.

Try this in a shell without Samba to validate.

If a group member could change permissions on a file they could setuid and escalate to the owner.

This is not really necessary for understanding this issue .... but ... just some background .... we are using a version control system in windows. When we check-in a file, this software attempts to set the file to read-only. But it fails. So to test, I tried to directly set the read-only flag in windows myself, and it also failed. So that's why I'm trying to do this. Me and another user are maintaining these files. So when we check-in a file, we need to be able to have the file set to read-only.

Neil,

What account is the version control system using?
What user/group/permissions is it creating the file with? (ie. can you provide an example of a file created by it).

Have you attempted to modify the default umask of the version control user?

Neil - Thanks for your replies. I'll think about this some more and see if I can confirm why this is happening.