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The 'systemd-analyze security' command looks at the unit file configuration and reports on any settings which increase the attack surface for the daemon. Since most systemd units are fairly minimalist, this is generally informing us about settings that we never put any thought into using before. In its current configuration it reports # systemd-analyze security virtlogd.service ...snip... → Overall exposure level for virtlogd.service: 9.6 UNSAFE 😨 which is pretty terrible as a score. If we apply all of the recommendations that appear possible without (knowingly) breaking functionality it reports: # systemd-analyze security virtlogd.service ...snip... → Overall exposure level for virtlogd.service: 2.2 OK 🙂 which is a pretty decent improvement. Some of the settings we would like to enable require a systemd version that is newer than that available in our oldest distro target - RHEL-8 at v239. NB, RestrictSUIDSGID is technically newer than 239, but RHEL-8 backported it, and other distros we target have it by default. Remaining recommendations are ✗ CapabilityBoundingSet=~CAP_(DAC_*|FOWNER|IPC_OWNER) We block FOWNER/IPC_OWNER, but can't block the two DAC capabilities. Historically apps/users might point QEMU to log files in $HOME, pre-created with their own user ID. ✗ IPAddressDeny= Not required since RestrictAddressFamilies blocks IP usage. Ignoring this avoids the overhead of creating a traffic filter than will never be used. ✗ NoNewPrivileges= Highly desirable, but cannot enable it yet, because it will block the ability to transition to the virtlogd_t SELinux domain during execve. The SELinux policy needs fixing to permit this transition under NNP first. ✗ PrivateTmp= There is a decent chance people have VMs configured with a serial port logfile pointing at /tmp. We would cause a regression to use private /tmp for logging ✗ PrivateUsers= This would put virtlogd inside a user namespace where its root is in fact unprivileged. Same problem as the User= setting below ✗ ProcSubset= Libraries we link to might read certain non-PID related files from /proc ✗ ProtectClock= Requires v245 ✗ ProtectHome= Same problem as PrivateTmp=. There's a decent chance that someone has a VM configured to write a logfile to /home ✗ ProtectHostname= Requires v241 ✗ ProtectKernelLogs Requires v244 ✗ ProtectProc Requires v247 ✗ ProtectSystem= We only set it to 'full', as 'strict' is not viable for our required usage ✗ RootDirectory=/RootImage= We are not capable of running inside a custom chroot given needs to write log files to arbitrary places ✗ RestrictAddressFamilies=~AF_UNIX We need AF_UNIX to communicate with other libvirt daemons ✗ SystemCallFilter=~@resources We link to libvirt.so which links to libnuma.so which has a constructor that calls set_mempolicy. This is highly undesirable todo during a constructor. ✗ User=/DynamicUser= This is highly desirable, but we currently read/write logs as root, and directories we're told to write into could be anywhere. So using a non-root user would have a major risk of regressions for applications and also have upgrade implications Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser
General Public License, version 2.1 (or later). Some parts of the code
that are not part of the C library may have the more restrictive GNU
General Public License, version 2.0 (or later). See the files
COPYING.LESSER and COPYING for full license
terms & conditions.
Installation
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- users@lists.libvirt.org (for user discussions)
- devel@lists.libvirt.org (for development only)
Further details on contacting the project are available on the website: