The system must have libcap2 installed. For example, the default Red Hat Enterprise Linux 5 installation doesn't have libcap2.
The filesystem must not be mounted as noexec or nosuid.
Linux Filesystem Capabilities must be enabled. For example, SUSE Linux Enterprise Server 11 has Linux Filesystem Capabilities disabled by default. For more information, see Non-privileged mode and Linux Filesystem Capabilities below.
See OneAgent security on Linux to learn about monitoring actions executed by OneAgent that require privileged access.
Privileges during installation
When run in non-privileged mode, the OneAgent installer requires superuser privileges to:
Set file capabilities for OneAgent binaries located at /opt/dynatrace/oneagent/agent/lib[64]/*.
Invoke the oneagent service script to start oneagentwatchdog.
On systems with systemd, communicate with systemd daemon via d-bus to run the following commands:
The unprivileged user is included in the service definition (unit file). The daemon runs the OneAgent service script in unprivileged mode, automatically dropping superuser privileges when the service script is executed.
Linux System Capabilities
Dynatrace OneAgent Watchdog starts and runs all other processes under an unprivileged user without superuser access. OneAgent binaries leverage the following Linux System Capabilities.
cap_dac_override2 - for filesystem accesscap_chown23 - for setting ownership of files replaced in the filesystem (e.g., runc binary)cap_fowner2 - for setting ownership of files replaced in the filesystemcap_sys_ptrace - for reading data from /proc pseudo-filesystem and tracing processescap_sys_resource3 - for reading processes resource limitscap_setuid4 - for temporary elevation of privileges to execute certain operations; for details, see Automatic updates and operationcap_kill356cap_setfcap356cap_fsetid356
oneagentnettracer
cap_bpf (kernel >=5.8)7cap_perfmon (kernel >=5.8)7cap_sys_admin (kernel <5.8, or when cap_bpf is explicitly blocked)7cap_dac_override``cap_sys_ptrace``cap_sys_resource
oneagentnetwork
cap_net_raw - for opening raw socketscap_net_admin8- for reading network interface information
oneagentloganalytics
cap_dac_read_search - for access to all logs stored on hostcap_sys_ptrace - for reading data from /proc pseudo-filesystem
oneagentplugin
cap_set_gid1- for adding docker to the process supplementary groups list, which allows for the container data to be retrieved
cap_sys_admin - for mount() syscallcap_dac_override - for inspection and modification of filesystems of the running containerscap_sys_ptrace - for tracing the Docker daemoncap_sys_chroot - for chroot() syscallcap_fowner - for changing ownership and permissions of files within container filesystemcap_fsetid - for changing ownership and permissions of files within container filesystem
OneAgent Installer executed during auto-update
cap_dac_override - for filesystem accesscap_chown - for filesystem accesscap_fowner - for filesystem accesscap_fsetid - for filesystem accesscap_kill - to be able to signal all the running processes, e.g. stopped orphaned OneAgent processescap_setfcap - for setting Linux Filesystem capabilities file capabilities on agent binaries during the installation
oneagentosconfig
cap_setuid6- for execution of privileged operations during the installation processcap_setgid6- for setting group ownership of files during the installation process
oneagenteventstracer
cap_sys_admin - for perf_event_open() syscallcap_dac_override - for access to /sys/kernel/debug/tracing
oneagentdmidecode
cap_dac_override - for filesystem access
oneagentmntconstat
cap_dac_read_search - for retrieving disk occupation stats with statvfs64()``cap_sys_chroot - for setns() syscallcap_sys_admin - for setns() syscallcap_sys_ptrace - for accessing /proc/1/ns
oneagentebpfdiscovery
cap_bpf (kernel >=5.8)7cap_perfmon (kernel >=5.8)7cap_sys_admin (kernel <5.8, or when cap_bpf is explicitly blocked)7cap_dac_override - for write access to /sys/kernel/debug/tracingcap_sys_resource - for removing memory usage limitation of the bpf program
1
Required only during initialization phase and is unconditionally dropped afterwards.
Only for kernels 5.8 and newer, unless usage of unprivileged cap_bpf is blocked by the OS, then it fallbacks to cap_sys_admin. For older kernel versions, cap_sys_admin is enabled instead.
Linux Filesystem Capabilities are required to install OneAgent in non-privileged mode. SUSE Linux Enterprise Server 11 has Linux Filesystem Capabilities disabled by default. These capabilities might also be disabled in other supported Linux distributions or as the result of a custom configuration. The OneAgent installer prints the following message if Linux Filesystem Capabilities are disabled:
Warning: Failed to enable non-privileged mode, kernel does not support file capabilities.
You can also check the kernel boot options to see if Linux Filesystem Capabilities are enabled. Run the following command to check your kernel boot options.
cat /proc/cmdline
If you find file_caps=1 in the output, your setup is fine.
To enable Linux Filesystem Capabilities, add file_caps=1 to your kernel boot options. For example, on SUSE Linux Enterprise Server 11, use YaST, edit kernel boot options, add file_caps=1, and reboot the machine.
Privileges during automatic updates and operation
The scope of privileges required by OneAgent depends on whether the kernel supports Linux ambient capabilities. As a general rule, kernel 4.3+ supports ambient capabilities. However, in the case of Red Hat Enterprise Linux, these may be supported in older kernel versions because of the Red Hat policy to backport patches. This makes ambient capabilities supported by kernel versions as old as 3.10.x.
During an automatic update, the installer starts under an unprivileged dtuser with proper ambient capabilities set. OneAgent doesn't require root access to perform an automatic update.
Red Hat Enterprise Linux 7 has a too low systemd (v219 instead of the required v221), and to be able to run automatic updates in non-privileged mode, we're temporarily elevating the privileges to run systemctl <start|stop|enable|disable> oneagent.service.
OneAgent will work under the non-privileged dtuser in the majority of cases. When the kernel doesn't provide ambient capabilities, it automatically elevates its privileges to the superuser level using setuid(0) in the following cases:
OneAgent automatic updates
Host OSI ID generation on Azure hosts
Docker containers properties detection
Self-diagnostics
If you don't want to grant the superuser permission level to OneAgent, you can disable it by adding the DISABLE_ROOT_FALLBACK=1 parameter to the OneAgent installation command. For example:
In such cases, you must perform manual updates on individual hosts. We don't recommend using the DISABLE_ROOT_FALLBACK=1 parameter for OneAgents on Azure or Docker containers.
How do I know if OneAgent operates in non-privileged mode?
The installer prints a message at the end of OneAgent installation. Depending on the kernel version and its support for ambient capabilities, you will see one of the following messages:
Non-privileged mode is enabled
The kernel supports ambient capabilities, the root access is not used for updates or operation.
Enabled non-privileged mode, but ambient capabilities are not supported by kernel
The kernel is within the minimum supported version, but due to non-supported ambient capabilities, OneAgent needs to elevate privileges in select cases, see above.
Failed to enable non-privileged mode
The kernel doesn't meet the minimum version requirements to enable non-privileged mode.