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Security

Privileges​

CEEMS exporter needs access to IPMI interface to get current power consumption which is only available for privileged users and/or processes. Thus, a trivial solution is to run CEEMS exporter as root. For accessing metrics from perf subsystem or to use eBPF, CEEMS exporter needs different types of privileges. Similarly, in order to which GPU has been assigned to which compute unit, we need to either introspect compute unit's environment variables (for SLURM resource manager), libvirt XML file for VM (for Openstack), etc. These actions need privileges as well. However, these privileges are only needed at specific points of execution in the exporter code and hence, running the exporter as root is an overkill.

We can leverage Linux Capabilities to assign just the necessary privileges to the process. Moreover, CEEMS apps are capability aware, i.e., the app will assume the privileges only when they are required during the code execution. It executes the piece of code that needs privileges in a separate thread and destroys the thread after finishing the execution to ensure no other goroutine will be scheduled on that thread. This ensures the whole exporter code runs as unprivileged process most of the time and raises the privileges only when necessary. This strategy makes CEEMS apps capability aware.

IMPORTANT

Even if operator starts any of the CEEMS app as root user, the app will just keep the capabilities that it needs and drops rest of them and switch to nobody user to ensure it runs with minimum necessary privileges. As stated above, it only raises the capabilities when needed and run rest of the time as unprivileged process.

Linux capabilities​

CEEMS Exporter​

For different collectors of CEEMS exporter, different capabilities are needed. The following list summaries the capabilities needed for each collector:

  • ipmi_dcmi: cap_setuid and cap_setgid to execute IPMI command as root.
  • slurm: cap_sys_ptrace and cap_dac_read_search to be able to access processes' environment variables to get GPU indices of a given compute job. If --collector.slurm.gpu-job-map-path is used, these capabilities wont be needed.
  • perf: cap_perfmon to be able to open perf events. cap_sys_ptrace and cap_dac_read_search to be able to access processes' environment variables when --collector.slurm.perf-env-var is used.
  • ebpf: cap_bpf and cap_perfmon to be able to load and access BPP programs and maps. For kernels < 5.11, cap_sys_resource is necessary to increase locked memory for loading BPF programs.
  • rapl: cap_dac_read_search when kernels > 5.3 is used as RAPL counters from this kernel version is only access to root.

CEEMS API Server​

Currently, SLURM resource manager of CEEMS API server only supports fetching job data from sacct command. It is possible to fetch jobs of all users for only slurm system user or root user. Thus, cap_setuid and cap_setgid are needed to execute this command as either slurm or root user.

If operators would like to add the user under which CEEMS API server is running under to SLURM users list, these capabilities wont be needed anymore.

CEEMS LB​

CEEMS LB do not need any special privileges and capabilities.

Systemd​

If CEEMS components are installed using RPM/DEB packages, a basic systemd unit file will be installed to start the service. However, when they are installed manually using pre-compiled binaries, it is necessary to install and configure systemd unit files to manage the service.

Linux capabilities can be assigned to either file or process. For instance, capabilities on the ceems_exporter and ceems_api_server binaries can be set as follows:

sudo setcap cap_sys_ptrace,cap_dac_read_search,cap_setuid,cap_setgid+p /full/path/to/ceems_exporter
sudo setcap cap_setuid,cap_setgid+p /full/path/to/ceems_api_server

This will assign all the capabilities that are necessary to run ceems_exporter for all the collectors. Using file based capabilities will expose those capabilities to anyone on the system that have execute permissions on the binary. Although, it does not pose a big security concern, it is better to assign capabilities to a process.

As operators tend to run the exporter within a systemd unit file, we can assign capabilities to the process rather than file using AmbientCapabilities directive of the systemd. An example is as follows:

[Service]
ExecStart=/usr/local/bin/ceems_exporter --collector.slurm --collector.perf.hardware-events --collector.ebpf.io-metrics
AmbientCapabilities=CAP_SYS_PTRACE CAP_DAC_READ_SEARCH CAP_SETUID CAP_SETGID CAP_PERFMON CAP_BPF CAP_SYS_RESOURCE

Note that it is bare minimum service file and it is only to demonstrate on how to use AmbientCapabilities. Production ready service files examples are provided in repo.

Containers​

If operators would like to deploy exporter inside a container, it is necessary to give full privileges to the container for the exporter to access different files under /dev, /sys and /proc. As stated in capabilities section, exporter will drop all the capabilities and keep only necessary ones based on runtime config and hence, running container as privileged does not pose a major security risk.