Re: Controlling execution of Java JAR files with SELinux RBAC

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 

Hello Phil:

Setting the categories instead of adding them with the "+" worked!

So it sounds like the chcat "+" option is not working as expected on CentOS 6.9.  Do you concur?

Thank you for your help Phil.

The following series of steps show that it now works as expected:

# uname -a

Linux es300h 2.6.32-696.1.1.el6.x86_64 #1 SMP Tue Apr 11 17:13:24 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

# cat /etc/redhat-release
CentOS release 6.9 (Final)

# semanage user -l

                Labeling   MLS/       MLS/                         
SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

git_shell_u     user       s0         s0                             git_shell_r
green_u         user       s0         s0                             green_r
guest_u         user       s0         s0                             guest_r
red_u           user       s0         s0                             red_r
root            user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
staff_u         user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
sysadm_u        user       s0         s0-s0:c0.c1023                 sysadm_r
system_u        user       s0         s0-s0:c0.c1023                 system_r unconfined_r
unconfined_u    user       s0         s0-s0:c0.c1023                 system_r unconfined_r
user_u          user       s0         s0                             user_r
xguest_u        user       s0         s0                             xguest_r

# semanage user -m -r s0-s0:c0.c1023 user_u

# semanage user -l

                Labeling   MLS/       MLS/                         
SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

git_shell_u     user       s0         s0                             git_shell_r
green_u         user       s0         s0                             green_r
guest_u         user       s0         s0                             guest_r
red_u           user       s0         s0                             red_r
root            user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
staff_u         user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
sysadm_u        user       s0         s0-s0:c0.c1023                 sysadm_r
system_u        user       s0         s0-s0:c0.c1023                 system_r unconfined_r
unconfined_u    user       s0         s0-s0:c0.c1023                 system_r unconfined_r
user_u          user       s0         s0-s0:c0.c1023                 user_r
xguest_u        user       s0         s0                             xguest_r

# cat /etc/selinux/targeted/setrans.conf
#
# Multi-Category Security translation table for SELinux
#
# Uncomment the following to disable translation libary
# disable=1
#
# Objects can be categorized with 0-1023 categories defined by the admin.
# Objects can be in more than one category at a time.
# Categories are stored in the system as c0-c1023.  Users can use this
# table to translate the categories into a more meaningful output.
# Examples:
# s0:c0=CompanyConfidential
# s0:c1=PatientRecord
# s0:c2=Unclassified
# s0:c3=TopSecret
# s0:c1,c3=CompanyConfidentialRedHat
s0:c0=NetworkAdministrator
s0:c1=Operator
s0=SystemLow
s0-s0:c0.c1023=SystemLow-SystemHigh
s0:c0.c1023=SystemHigh

# service mcstrans restart
Stopping mcstransd:                                        [  OK  ]
Starting mcstransd:                                        [  OK  ]

# chcat -L
s0:c0                          NetworkAdministrator
s0:c1                          Operator
s0                             SystemLow
s0-s0:c0.c1023                 SystemLow-SystemHigh
s0:c0.c1023                    SystemHigh

# useradd foo

# useradd bar

# passwd foo
Changing password for user foo.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

# passwd bar
Changing password for user bar.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

# semanage login -a foo

# semanage login -a bar

# chcat -l -- c0 foo

# chcat -l -- c1 bar

# semanage login -l

Login Name                SELinux User              MLS/MCS Range           

__default__               unconfined_u              SystemLow-SystemHigh    
bar                       user_u                    SystemLow-Operator      
foo                       user_u                    SystemLow-NetworkAdministrator
root                      unconfined_u              SystemLow-SystemHigh    
system_u                  system_u                  SystemLow-SystemHigh    

# chcat -L -l foo bar
foo: NetworkAdministrator
bar: Operator

# chcat -- +NetworkAdministrator /usr/local/soup/bin/foo.jar

# ls -Z /usr/local/soup/bin/foo.jar
-rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/foo.jar

Now as the Linux user, foo, it works as expected:

$ whoami
foo

$ id -Z
user_u:user_r:user_t:SystemLow-NetworkAdministrator

$ java -jar /usr/local/soup/bin/foo.jar

Hello from the foo application

Now as the Linux user, bar, it also works as expected:

$ whoami
bar

$ id -Z
user_u:user_r:user_t:SystemLow-Operator

$ java -jar /usr/local/soup/bin/foo.jar
Error: Unable to access jarfile /usr/local/soup/bin/foo.jar

Regards,

Bill

On 05/28/2017 05:22 PM, Philip Seeley wrote:

Hi Bill,

I saw in a previous post that you were using CentOS 6.9 so this should work for you. It looks like the login configuration is not quite right as both users are showing SystemLow-SystemHigh when they logon.

Check the login config shows they only have the categories they need, i.e. jack has c0 and mary has c1.

If they're not correct try setting the categories rather than adding to them with a "+":

[root@centos6 ~]# chcat -l -- c0 jack
[root@centos6 ~]# chcat -l -- c1 mary

[root@centos6 ~]# semanage login -l

Login Name                SELinux User              MLS/MCS Range            

__default__               unconfined_u              s0-s0:c0.c1023          
jack                      user_u                    s0-s0:c0                
mary                      user_u                    s0-s0:c1                
root                      unconfined_u              s0-s0:c0.c1023          
system_u                  system_u                  s0-s0:c0.c1023          

Then with:

# ll -Z /usr/local/bin/
-rw-r--r--. root root unconfined_u:object_r:bin_t:s0:c0 jack
-rw-r--r--. root root unconfined_u:object_r:bin_t:s0:c1 mary
[root@centos6 ~]# cat /etc/system-release
CentOS release 6.9 (Final)

as jack:

[jack@centos6 ~]$ id
uid=500(jack) gid=500(jack) groups=500(jack) context=user_u:user_r:user_t:s0-s0:c0
[jack@centos6 ~]$ cat /usr/local/bin/jack
Hi
[jack@centos6 ~]$ cat /usr/local/bin/mary
cat: /usr/local/bin/mary: Permission denied

and as mary:

[mary@centos6 ~]$ id
uid=501(mary) gid=501(mary) groups=501(mary) context=user_u:user_r:user_t:s0-s0:c1
[mary@centos6 ~]$ cat /usr/local/bin/jack
cat: /usr/local/bin/jack: Permission denied
[mary@centos6 ~]$ cat /usr/local/bin/mary
Hi

Cheers

Phil

Inactive hide details for Bill D ---26/05/2017 05:19:44---Hello Phil: Thank you for the response. Your suggested fix resolved Bill D ---26/05/2017 05:19:44---Hello Phil: Thank you for the response. Your suggested fix resolved the error.

From: Bill D <littus@xxxxxxxxxx>
To: Philip Seeley <pseeley@xxxxxxxxxxx>
Cc: littus@xxxxxxxxxx, selinux@xxxxxxxxxxxxxxxxxxxxxxx
Date: 26/05/2017 05:19
Subject: Re: Controlling execution of Java JAR files with SELinux RBAC




Hello Phil:

Thank you for the response.  Your suggested fix resolved the error.

However, I am unable to get the desired effect.

I am not able to prevent a Linux user from running/accessing a Java JAR file using SELinux categories.

I would appreciate any other hints to make this work.

Following are the details of what I did:

# semanage user -l

                Labeling   MLS/       MLS/                         
SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

git_shell_u     user       SystemLow  SystemLow                      git_shell_r
guest_u         user       SystemLow  SystemLow                      guest_r
root            user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
staff_u         user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
sysadm_u        user       SystemLow  SystemLow-SystemHigh           sysadm_r
system_u        user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
unconfined_u    user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
user_u          user       SystemLow  SystemLow                      user_r
xguest_u        user       SystemLow  SystemLow                      xguest_r

# semanage user -m -r s0-s0:c0.c1023 user_u

# semanage user -l

                Labeling   MLS/       MLS/                         
SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

git_shell_u     user       SystemLow  SystemLow                      git_shell_r
guest_u         user       SystemLow  SystemLow                      guest_r
root            user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
staff_u         user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
sysadm_u        user       SystemLow  SystemLow-SystemHigh           sysadm_r
system_u        user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
unconfined_u    user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
user_u          user       SystemLow  SystemLow-SystemHigh           user_r
xguest_u        user       SystemLow  SystemLow                      xguest_r


# cat setrans.conf

#
# Multi-Category Security translation table for SELinux
#
# Uncomment the following to disable translation libary
# disable=1
#
# Objects can be categorized with 0-1023 categories defined by the admin.
# Objects can be in more than one category at a time.
# Categories are stored in the system as c0-c1023.  Users can use this
# table to translate the categories into a more meaningful output.
# Examples:
# s0:c0=CompanyConfidential
# s0:c1=PatientRecord
# s0:c2=Unclassified
# s0:c3=TopSecret
# s0:c1,c3=CompanyConfidentialRedHat
s0:c0=NetworkAdministrator
s0:c1=Operator
s0=SystemLow
s0-s0:c0.c1023=SystemLow-SystemHigh
s0:c0.c1023=SystemHigh

# service mcstrans restart
Stopping mcstransd:                                        [  OK  ]
Starting mcstransd:                                        [  OK  ]

# chcat -L
s0:c0                          NetworkAdministrator
s0:c1                          Operator
s0                             SystemLow
s0-s0:c0.c1023                 SystemLow-SystemHigh
s0:c0.c1023                    SystemHigh

# useradd foo

# useradd bar

# passwd foo
Changing password for user foo.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

# passwd bar
Changing password for user bar.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

# semanage login -a foo

# semanage login -a bar

# chcat -l -- +NetworkAdministrator foo

# chcat -l -- +Operator bar

# chcat -L -l bar foo
bar: s0:c0.c1023,c1    <===== why is it not just s0:c1?
foo: s0:c0.c1023,c0    <===== why is it not just just s0:c0?

# chcat -- +NetworkAdministrator /usr/local/soup/bin/Foo.jar

# ls -Z /usr/local/soup/bin/Foo.jar
-rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar

Now Login as the 'foo' Linux user and notice that it can run Foo.jar as expected

$ whoami
foo

$ id -Z
user_u:user_r:user_t:SystemLow-SystemHigh

$ ls -Z /usr/local/soup/bin/Foo.jar
-rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar

$ java -jar /usr/local/soup/bin/Foo.jar
Hello Foo

Now login as the 'bar' Linux user and notice that it can also run Foo.jar which is NOT expected

$ whoami
bar

$ id -Z
user_u:user_r:user_t:SystemLow-SystemHigh

$ ls -Z /usr/local/soup/bin/Foo.jar
-rwxr-xr-x. admin admin system_u:object_r:bin_t:NetworkAdministrator /usr/local/soup/bin/Foo.jar

$ java -jar /usr/local/soup/bin/Foo.jar
Hello Foo

Why is Linux user 'bar' able to run/access Foo.jar when its category doesn't match Foo.jar's category?

Following is how to create the Foo.jar file:

$ cat Foo.java
public class Foo {
    public static void main(String[] args) {
        System.out.println("Hello Foo");
    }
}

$ cat manifest.txt
Main-Class:

$ javac Foo.java

$ jar cvfe Foo.jar Foo Foo.class
added manifest
adding: Foo.class(in = 409) (out= 282)(deflated 31%)

Best Regards,

Bill

On 05/24/2017 04:39 PM, Philip Seeley wrote:
      Hi Bill,

      I think this was my mistake in transcribing. The user_u line after the "semanage user -m" command should be:

      user_u          user       SystemLow  SystemLow-SystemHigh                      user_r

      So the command should have been:

      semanage user -m -r s0-s0:c0.c1023 user_u

      Or even:

      semanage user -m -r SystemLow-SystemHigh user_u

      Appologies for that.

      Phil

      Inactive hide details for Bill D ---25/05/2017 02:28:19---Hello Phil, I have tried your suggestion of extending the user_u defiBill D ---25/05/2017 02:28:19---Hello Phil, I have tried your suggestion of extending the user_u definition without

      From:       Bill D <littus@xxxxxxxxxx>
      To:       Philip Seeley <pseeley@xxxxxxxxxxx>
      Cc:       littus@xxxxxxxxxx, selinux@xxxxxxxxxxxxxxxxxxxxxxx
      Date:       25/05/2017 02:28
      Subject:       Re: Controlling execution of Java JAR files with SELinux RBAC




      Hello Phil,

      I have tried your suggestion of extending the user_u definition without success:

      # semanage user -l

                      Labeling   MLS/       MLS/                         
      SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

      git_shell_u     user       SystemLow  SystemLow                      git_shell_r
      guest_u         user       SystemLow  SystemLow                      guest_r
      root            user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
      staff_u         user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
      sysadm_u        user       SystemLow  SystemLow-SystemHigh           sysadm_r
      system_u        user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
      unconfined_u    user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
      user_u          user       SystemLow  SystemLow                      user_r
      xguest_u        user       SystemLow  SystemLow                      xguest_r

      # semanage user -m -r s0:c0.c1023 user_u

      # semanage user -l

                      Labeling   MLS/       MLS/                         
      SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

      git_shell_u     user       SystemLow  SystemLow                      git_shell_r
      guest_u         user       SystemLow  SystemLow                      guest_r
      root            user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
      staff_u         user       SystemLow  SystemLow-SystemHigh           staff_r sysadm_r system_r unconfined_r
      sysadm_u        user       SystemLow  SystemLow-SystemHigh           sysadm_r
      system_u        user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
      unconfined_u    user       SystemLow  SystemLow-SystemHigh           system_r unconfined_r
      user_u          user       SystemLow  SystemHigh                     user_r
      xguest_u        user       SystemLow  SystemLow                      xguest_r

      # useradd kate

      # passwd kate
      Changing password for user kate.
      New password:
      Retype new password:
      passwd: all authentication tokens updated successfully.

      # semanage login -a kate
      libsemanage.validate_handler: MLS range s0 for Unix user regularuser exceeds allowed range s0:c0.c1023 for SELinux user user_u (No such file or directory).
      libsemanage.validate_handler: seuser mapping [regularuser -> (user_u, s0)] is invalid (No such file or directory).
      libsemanage.dbase_llist_iterate: could not iterate over records (No such file or directory).
      /usr/sbin/semanage: Could not commit semanage transaction

      I would greatly appreciate any other hints to make this work.

      Regards,

      Bill

      On 5/23/2017 8:42 PM, Philip Seeley wrote:

              Hi Bill,

              This is probably because the default RHEL6 configuration does not include any categories in the user_u SELinux user's range:

              # semanage user -l

                              Labeling   MLS/       MLS/                          
              SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

              guest_u         user       s0         s0                             guest_r
              root            user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
              staff_u         user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
              sysadm_u        user       s0         s0-s0:c0.c1023                 sysadm_r
              system_u        user       s0         s0-s0:c0.c1023                 system_r unconfined_r
              unconfined_u    user       s0         s0-s0:c0.c1023                 system_r unconfined_r
              user_u          user       s0         s0                             user_r

              You probably have to extend the user definition to include the categories you're using. As an example, this gives all categories:

              # semanage user -m -r s0:c0.c1023 user_u

              # semanage user -l

                              Labeling   MLS/       MLS/                          
              SELinux User    Prefix     MCS Level  MCS Range                      SELinux Roles

              guest_u         user       s0         s0                             guest_r
              root            user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
              staff_u         user       s0         s0-s0:c0.c1023                 staff_r sysadm_r system_r unconfined_r
              sysadm_u        user       s0         s0-s0:c0.c1023                 sysadm_r
              system_u        user       s0         s0-s0:c0.c1023                 system_r unconfined_r
              unconfined_u    user       s0         s0-s0:c0.c1023                 system_r unconfined_r
              user_u          user       s0         s0:c0.c1023                    user_r

              Hope that helps.

              Phil


              Inactive hide details for Bill Durant ---24/05/2017 12:34:53---Hello Phil: Thank you for the suggestion. I have tried the stepBill Durant ---24/05/2017 12:34:53---Hello Phil: Thank you for the suggestion. I have tried the steps from the URL that

              From:               Bill Durant <littus@xxxxxxxxxx>
              To:               Philip Seeley <pseeley@xxxxxxxxxxx>
              Cc:               littus@xxxxxxxxxx, selinux@xxxxxxxxxxxxxxxxxxxxxxx
              Date:               24/05/2017 12:34
              Subject:               Re: Controlling execution of Java JAR files with SELinux RBAC



              Hello Phil:

              Thank you for the suggestion.  I have tried the steps from the URL that you provided without success.

              I get an error when I try to assign Linux user mary to an SELinux login as follows:

              # cat /etc/redhat-release
              CentOS release 6.9 (Final)

              ;;; Add "s0:c0=NetworkAdministrator" and "s0:c1=Operator" to /etc/selinux/targeted/setrans.conf

              # cat /etc/selinux/targeted/setrans.conf
              #
              # Multi-Category Security translation table for SELinux
              #
              # Uncomment the following to disable translation libary
              # disable=1
              #
              # Objects can be categorized with 0-1023 categories defined by the admin.
              # Objects can be in more than one category at a time.
              # Categories are stored in the system as c0-c1023.  Users can use this
              # table to translate the categories into a more meaningful output.
              # Examples:
              # s0:c0=CompanyConfidential
              # s0:c1=PatientRecord
              # s0:c2=Unclassified
              # s0:c3=TopSecret
              # s0:c1,c3=CompanyConfidentialRedHat
              s0:c0=NetworkAdministrator
              s0:c1=Operator
              s0=SystemLow
              s0-s0:c0.c1023=SystemLow-SystemHigh
              s0:c0.c1023=SystemHigh

              # service mcstrans start

              # chcat -L
              s0:c0                          NetworkAdministrator
              s0:c1                          Operator
              s0                             SystemLow
              s0-s0:c0.c1023                 SystemLow-SystemHigh
              s0:c0.c1023                    SystemHigh


              # useradd mary
              # passwd mary
              Changing password for user mary.
              New password:
              Retype new password:
              passwd: all authentication tokens updated successfully.

              # semanage login -a mary

              # chcat -l -- +NetworkAdministrator mary
              libsemanage.validate_handler: MLS range s0-s0:c0 for Unix user mary exceeds allowed range s0 for SELinux user user_u (No such file or directory).
              libsemanage.validate_handler: seuser mapping [mary -> (user_u, s0-s0:c0)] is invalid (No such file or directory).
              libsemanage.dbase_llist_iterate: could not iterate over records (No such file or directory).
              /usr/sbin/semanage: Could not commit semanage transaction

              I would appreciate any hints on how to resolve that error.

              Thanks!

              Bill


              On 05/23/2017 05:49 PM, Philip Seeley wrote: 








_______________________________________________
selinux mailing list -- selinux@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe send an email to selinux-leave@xxxxxxxxxxxxxxxxxxxxxxx
[Index of Archives]     [Fedora Users]     [Fedora Desktop]     [Big List of Linux Books]     [Yosemite News]     [Yosemite Campsites]     [KDE Users]     [Gnome Users]

  Powered by Linux