85 lines
4.1 KiB
Plaintext
85 lines
4.1 KiB
Plaintext
Red Hat Security Enhancements for tog-pegasus
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Access to the Pegasus services:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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By default, with the configuration as shipped, the upstream Open Group Pegasus
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release allowed any user with an account on the machine (including root) to
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use the network HTTPS port 5989 (by default) and HTTP port 5988 services.
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On authentication failures, though there was the standard PAM authentication
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failure delay, no messages were logged to syslog. This meant that potentially
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a long-running cracker process could try millions of root passwords over the
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network and could possibly discover the root password . If users were unwise
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enough to enable the HTTP service on port 5988, then root passwords could be
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sent unencrypted over the network.
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This situation was deemed unacceptable by Red Hat RHEL QA test and Security
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Response team engineers.
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So for the Red Hat tog-pegasus release, PAM access control was enabled, to
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remove these vulnerabilities. There is now a "pegasus" user created during
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install, and users are recommended to use only that user to invoke CIM
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operations over the network.
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By default:
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o root password authentication for CIM operations invoked over the network
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HTTPS/HTTP services is denied - the root user is unable to invoke pegasus
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services over the network - only the "pegasus" user may do so.
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o the root user may invoke CIM operations over the HTTPS/HTTP ports on the
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local machine.
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o any user other than "pegasus" or "root" may not invoke pegasus services
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over the HTTPS/HTTP ports at all.
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o any PAM authentication failure will be logged to syslog
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NOTE: after installation, you must set the password for the pegasus user -
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issue this command as root :
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# passwd pegasus
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- to enable CIM operation network service, if the pegasus user is
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a local system user.
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Note also that even though a non-root user's password is used to authenticate
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with the cimserver, the cimserver and all CIM Operation Providers run as root.
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This was another reason to restrict use of CIM Operations to only one user.
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The "pegasus" user may of course be a NIS, Kerberos, or LDAP user, which
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could be used as configured in /etc/nsswitch.conf or with the PAM stack.
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You may configure this differently, and at your own risk, by modifying the
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pam_access configuration file /etc/Pegasus/access.conf, or by removing the
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line:
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account required pam_access.so accessfile=/etc/Pegasus/access.conf
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from /etc/pam.d/wbem - then tog-pegasus' authentication behaviour would
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be the same as that of the upstream release.
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SELinux
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~~~~~~~
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There is an SELinux policy for tog-pegasus shipped in selinux-policy-targeted-1.17.30-2.110+ .
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When SELinux is enabled in enforcing mode, the cimserver and providers are restricted to the
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operations allowed to the 'pegasus_t' security context. Also only the pegasus_exec_t context
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may modify the repository, and only the pegasus_exec_conf_t context may modify the pegasus
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configuration files which are of pegasus_conf_t file context.
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It is also possible to have separate SELinux policy for each provider. Create wrapper
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in '/usr/libexec/pegasus' with its own specific SELinux label for each confined provider.
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The wrapper file name has to be in specific format '$MODULE-cimprovagt' (where $MODULE is
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value of PG_ProviderModule.ModuleGroupName as set during registration of the provider).
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Original Pegasus's cimprovagt binary was moved to '/usr/libexec/pegasus/cimprovagt',
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'/usr/sbin/cimprovagt' is simple shell script now, which passes all arguments to provider specific
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wrapper if it exists or directly to original cimprovagt in other cases.
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See example wrapper for Operating System Provider from sblim-cmpi-base package (which instruments
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Linux_OperatingSystem class):
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cmpiOSBase_OperatingSystemProvider-cimprovagt.example
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ExecShield
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~~~~~~~~~~
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All tog-pegasus binary executables are compiled with ExecShield enabled, which make it nearly
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impossible to modify them or to poke executable code into them.
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