SYSTEMD.RESOURCE-CONTROL(5)systemd.resource-controlSYSTEMD.RESOURCE-CONTROL(5)
NAME
systemd.resource-control - Resource control unit settings
SYNOPSIS
slice.slice, scope.scope, service.service, socket.socket, mount.mount,
swap.swap
DESCRIPTION
Unit configuration files for services, slices, scopes, sockets, mount
points, and swap devices share a subset of configuration options for
resource control of spawned processes. Internally, this relies on the
Linux Control Groups (cgroups) kernel concept for organizing processes
in a hierarchical tree of named groups for the purpose of resource
management.
This man page lists the configuration options shared by those six unit
types. See systemd.unit(5) for the common options of all unit
configuration files, and systemd.slice(5), systemd.scope(5),
systemd.service(5), systemd.socket(5), systemd.mount(5), and
systemd.swap(5) for more information on the specific unit configuration
files. The resource control configuration options are configured in the
[Slice], [Scope], [Service], [Socket], [Mount], or [Swap] sections,
depending on the unit type.
In addition, options which control resources available to programs
executed by systemd are listed in systemd.exec(5). Those options
complement options listed here.
Enabling and disabling controllers
Controllers in the cgroup hierarchy are hierarchical, and resource
control is realized by distributing resource assignments between
siblings in branches of the cgroup hierarchy. There is no need to
explicitly enable a cgroup controller for a unit. systemd will
instruct the kernel to enable a controller for a given unit when this
unit has configuration for a given controller. For example, when
CPUWeight= is set, the cpu controller will be enabled, and when
TasksMax= are set, the pids controller will be enabled. In addition,
various controllers may be also be enabled explicitly via the
MemoryAccounting=/TasksAccounting=/IOAccounting= settings. Because of
how the cgroup hierarchy works, controllers will be automatically
enabled for all parent units and for any sibling units starting with
the lowest level at which a controller is enabled. Units for which a
controller is enabled may be subject to resource control even if they
don't have any explicit configuration.
Setting Delegate= enables any delegated controllers for that unit (see
below). The delegatee may then enable controllers for its children as
appropriate. In particular, if the delegatee is systemd (in the
user@.service unit), it will repeat the same logic as the system
instance and enable controllers for user units which have resource
limits configured, and their siblings and parents and parents'
siblings.
Controllers may be disabled for parts of the cgroup hierarchy with
DisableControllers= (see below).
Example 1. Enabling and disabling controllers
-.slice
/ \
/-----/ \--------------\
/ \
system.slice user.slice
/ \ / \
/ \ / \
/ \ user@42.service user@1000.service
/ \ Delegate= Delegate=yes
a.service b.slice / \
CPUWeight=20 DisableControllers=cpu / \
/ \ app.slice session.slice
/ \ CPUWeight=100 CPUWeight=100
/ \
b1.service b2.service
CPUWeight=1000
In this hierarchy, the cpu controller is enabled for all units shown
except b1.service and b2.service. Because there is no explicit
configuration for system.slice and user.slice, CPU resources will be
split equally between them. Similarly, resources are allocated equally
between children of user.slice and between the child slices beneath
user@1000.service. Assuming that there is no futher configuration of
resources or delegation below slices app.slice or session.slice, the
cpu controller would not be enabled for units in those slices and CPU
resources would be further allocated using other mechanisms, e.g. based
on nice levels. The manager for user 42 has delegation enabled without
any controllers, i.e. it can manipulate its subtree of the cgroup
hierarchy, but without resource control.
In the slice system.slice, CPU resources are split 1:6 for service
a.service, and 5:6 for slice b.slice, because slice b.slice gets the
default value of 100 for cpu.weight when CPUWeight= is not set.
CPUWeight= setting in service b2.service is neutralized by
DisableControllers= in slice b.slice, so the cpu controller would not
be enabled for services b1.service and b2.service, and CPU resources
would be further allocated using other mechanisms, e.g. based on nice
levels.
Setting resource controls for a group of related units
As described in systemd.unit(5), the settings listed here may be set
through the main file of a unit and drop-in snippets in *.d/
directories. The list of directories searched for drop-ins includes
names formed by repeatedly truncating the unit name after all dashes.
This is particularly convenient to set resource limits for a group of
units with similar names.
For example, every user gets their own slice user-nnn.slice. Drop-ins
with local configuration that affect user 1000 may be placed in
/etc/systemd/system/user-1000.slice,
/etc/systemd/system/user-1000.slice.d/*.conf, but also
/etc/systemd/system/user-.slice.d/*.conf. This last directory applies
to all user slices.
See the New Control Group Interfaces[1] for an introduction on how to
make use of resource control APIs from programs.
IMPLICIT DEPENDENCIES
The following dependencies are implicitly added:
• Units with the Slice= setting set automatically acquire Requires=
and After= dependencies on the specified slice unit.
OPTIONS
Units of the types listed above can have settings for resource control
configuration:
CPUAccounting=
Turn on CPU usage accounting for this unit. Takes a boolean
argument. Note that turning on CPU accounting for one unit will
also implicitly turn it on for all units contained in the same
slice and for all its parent slices and the units contained
therein. The system default for this setting may be controlled with
DefaultCPUAccounting= in systemd-system.conf(5).
Under the unified cgroup hierarchy, CPU accounting is available for
all units and this setting has no effect.
CPUWeight=weight, StartupCPUWeight=weight
These settings control the cpu controller in the unified hierarchy.
These options accept an integer value or a the special string
"idle":
• If set to an integer value, assign the specified CPU time
weight to the processes executed, if the unified control group
hierarchy is used on the system. These options control the
"cpu.weight" control group attribute. The allowed range is 1 to
10000. Defaults to unset, but the kernel default is 100. For
details about this control group attribute, see Control Groups
v2[2] and CFS Scheduler[3]. The available CPU time is split up
among all units within one slice relative to their CPU time
weight. A higher weight means more CPU time, a lower weight
means less.
• If set to the special string "idle", mark the cgroup for "idle
scheduling", which means that it will get CPU resources only
when there are no processes not marked in this way to execute
in this cgroup or its siblings. This setting corresponds to the
"cpu.idle" cgroup attribute.
Note that this value only has an effect on cgroup-v2, for
cgroup-v1 it is equivalent to the minimum weight.
While StartupCPUWeight= applies to the startup and shutdown phases
of the system, CPUWeight= applies to normal runtime of the system,
and if the former is not set also to the startup and shutdown
phases. Using StartupCPUWeight= allows prioritizing specific
services at boot-up and shutdown differently than during normal
runtime.
In addition to the resource allocation performed by the cpu
controller, the kernel may automatically divide resources based on
session-id grouping, see "The autogroup feature" in sched(7). The
effect of this feature is similar to the cpu controller with no
explicit configuration, so users should be careful to not mistake
one for the other.
CPUQuota=
This setting controls the cpu controller in the unified hierarchy.
Assign the specified CPU time quota to the processes executed.
Takes a percentage value, suffixed with "%". The percentage
specifies how much CPU time the unit shall get at maximum, relative
to the total CPU time available on one CPU. Use values > 100% for
allotting CPU time on more than one CPU. This controls the
"cpu.max" attribute on the unified control group hierarchy and
"cpu.cfs_quota_us" on legacy. For details about these control group
attributes, see Control Groups v2[2] and CFS Bandwidth Control[4].
Setting CPUQuota= to an empty value unsets the quota.
Example: CPUQuota=20% ensures that the executed processes will
never get more than 20% CPU time on one CPU.
CPUQuotaPeriodSec=
This setting controls the cpu controller in the unified hierarchy.
Assign the duration over which the CPU time quota specified by
CPUQuota= is measured. Takes a time duration value in seconds, with
an optional suffix such as "ms" for milliseconds (or "s" for
seconds.) The default setting is 100ms. The period is clamped to
the range supported by the kernel, which is [1ms, 1000ms].
Additionally, the period is adjusted up so that the quota interval
is also at least 1ms. Setting CPUQuotaPeriodSec= to an empty value
resets it to the default.
This controls the second field of "cpu.max" attribute on the
unified control group hierarchy and "cpu.cfs_period_us" on legacy.
For details about these control group attributes, see Control
Groups v2[2] and CFS Scheduler[3].
Example: CPUQuotaPeriodSec=10ms to request that the CPU quota is
measured in periods of 10ms.
AllowedCPUs=, StartupAllowedCPUs=
This setting controls the cpuset controller in the unified
hierarchy.
Restrict processes to be executed on specific CPUs. Takes a list of
CPU indices or ranges separated by either whitespace or commas. CPU
ranges are specified by the lower and upper CPU indices separated
by a dash.
Setting AllowedCPUs= or StartupAllowedCPUs= doesn't guarantee that
all of the CPUs will be used by the processes as it may be limited
by parent units. The effective configuration is reported as
EffectiveCPUs=.
While StartupAllowedCPUs= applies to the startup and shutdown
phases of the system, AllowedCPUs= applies to normal runtime of the
system, and if the former is not set also to the startup and
shutdown phases. Using StartupAllowedCPUs= allows prioritizing
specific services at boot-up and shutdown differently than during
normal runtime.
This setting is supported only with the unified control group
hierarchy.
AllowedMemoryNodes=, StartupAllowedMemoryNodes=
These settings control the cpuset controller in the unified
hierarchy.
Restrict processes to be executed on specific memory NUMA nodes.
Takes a list of memory NUMA nodes indices or ranges separated by
either whitespace or commas. Memory NUMA nodes ranges are specified
by the lower and upper NUMA nodes indices separated by a dash.
Setting AllowedMemoryNodes= or StartupAllowedMemoryNodes= doesn't
guarantee that all of the memory NUMA nodes will be used by the
processes as it may be limited by parent units. The effective
configuration is reported as EffectiveMemoryNodes=.
While StartupAllowedMemoryNodes= applies to the startup and
shutdown phases of the system, AllowedMemoryNodes= applies to
normal runtime of the system, and if the former is not set also to
the startup and shutdown phases. Using StartupAllowedMemoryNodes=
allows prioritizing specific services at boot-up and shutdown
differently than during normal runtime.
This setting is supported only with the unified control group
hierarchy.
MemoryAccounting=
This setting controls the memory controller in the unified
hierarchy.
Turn on process and kernel memory accounting for this unit. Takes a
boolean argument. Note that turning on memory accounting for one
unit will also implicitly turn it on for all units contained in the
same slice and for all its parent slices and the units contained
therein. The system default for this setting may be controlled with
DefaultMemoryAccounting= in systemd-system.conf(5).
MemoryMin=bytes, MemoryLow=bytes
These settings control the memory controller in the unified
hierarchy.
Specify the memory usage protection of the executed processes in
this unit. When reclaiming memory, the unit is treated as if it was
using less memory resulting in memory to be preferentially
reclaimed from unprotected units. Using MemoryLow= results in a
weaker protection where memory may still be reclaimed to avoid
invoking the OOM killer in case there is no other reclaimable
memory.
For a protection to be effective, it is generally required to set a
corresponding allocation on all ancestors, which is then
distributed between children (with the exception of the root
slice). Any MemoryMin= or MemoryLow= allocation that is not
explicitly distributed to specific children is used to create a
shared protection for all children. As this is a shared protection,
the children will freely compete for the memory.
Takes a memory size in bytes. If the value is suffixed with K, M, G
or T, the specified memory size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively.
Alternatively, a percentage value may be specified, which is taken
relative to the installed physical memory on the system. If
assigned the special value "infinity", all available memory is
protected, which may be useful in order to always inherit all of
the protection afforded by ancestors. This controls the
"memory.min" or "memory.low" control group attribute. For details
about this control group attribute, see Memory Interface Files[5].
Units may have their children use a default "memory.min" or
"memory.low" value by specifying DefaultMemoryMin= or
DefaultMemoryLow=, which has the same semantics as MemoryMin= and
MemoryLow=. This setting does not affect "memory.min" or
"memory.low" in the unit itself. Using it to set a default child
allocation is only useful on kernels older than 5.7, which do not
support the "memory_recursiveprot" cgroup2 mount option.
MemoryHigh=bytes
These settings control the memory controller in the unified
hierarchy.
Specify the throttling limit on memory usage of the executed
processes in this unit. Memory usage may go above the limit if
unavoidable, but the processes are heavily slowed down and memory
is taken away aggressively in such cases. This is the main
mechanism to control memory usage of a unit.
Takes a memory size in bytes. If the value is suffixed with K, M, G
or T, the specified memory size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively.
Alternatively, a percentage value may be specified, which is taken
relative to the installed physical memory on the system. If
assigned the special value "infinity", no memory throttling is
applied. This controls the "memory.high" control group attribute.
For details about this control group attribute, see Memory
Interface Files[5].
MemoryMax=bytes
These settings control the memory controller in the unified
hierarchy.
Specify the absolute limit on memory usage of the executed
processes in this unit. If memory usage cannot be contained under
the limit, out-of-memory killer is invoked inside the unit. It is
recommended to use MemoryHigh= as the main control mechanism and
use MemoryMax= as the last line of defense.
Takes a memory size in bytes. If the value is suffixed with K, M, G
or T, the specified memory size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively.
Alternatively, a percentage value may be specified, which is taken
relative to the installed physical memory on the system. If
assigned the special value "infinity", no memory limit is applied.
This controls the "memory.max" control group attribute. For details
about this control group attribute, see Memory Interface Files[5].
MemorySwapMax=bytes
These settings control the memory controller in the unified
hierarchy.
Specify the absolute limit on swap usage of the executed processes
in this unit.
Takes a swap size in bytes. If the value is suffixed with K, M, G
or T, the specified swap size is parsed as Kilobytes, Megabytes,
Gigabytes, or Terabytes (with the base 1024), respectively. If
assigned the special value "infinity", no swap limit is applied.
This controls the "memory.swap.max" control group attribute. For
details about this control group attribute, see Memory Interface
Files[5].
TasksAccounting=
This setting controls the pids controller in the unified hierarchy.
Turn on task accounting for this unit. Takes a boolean argument. If
enabled, the kernel will keep track of the total number of tasks in
the unit and its children. This number includes both kernel threads
and userspace processes, with each thread counted individually.
Note that turning on tasks accounting for one unit will also
implicitly turn it on for all units contained in the same slice and
for all its parent slices and the units contained therein. The
system default for this setting may be controlled with
DefaultTasksAccounting= in systemd-system.conf(5).
TasksMax=N
This setting controls the pids controller in the unified hierarchy.
Specify the maximum number of tasks that may be created in the
unit. This ensures that the number of tasks accounted for the unit
(see above) stays below a specific limit. This either takes an
absolute number of tasks or a percentage value that is taken
relative to the configured maximum number of tasks on the system.
If assigned the special value "infinity", no tasks limit is
applied. This controls the "pids.max" control group attribute. For
details about this control group attribute, the pids controller[6].
The system default for this setting may be controlled with
DefaultTasksMax= in systemd-system.conf(5).
IOAccounting=
This setting controls the io controller in the unified hierarchy.
Turn on Block I/O accounting for this unit, if the unified control
group hierarchy is used on the system. Takes a boolean argument.
Note that turning on block I/O accounting for one unit will also
implicitly turn it on for all units contained in the same slice and
all for its parent slices and the units contained therein. The
system default for this setting may be controlled with
DefaultIOAccounting= in systemd-system.conf(5).
IOWeight=weight, StartupIOWeight=weight
These settings control the io controller in the unified hierarchy.
Set the default overall block I/O weight for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a single weight value (between 1 and 10000) to set
the default block I/O weight. This controls the "io.weight" control
group attribute, which defaults to 100. For details about this
control group attribute, see IO Interface Files[7]. The available
I/O bandwidth is split up among all units within one slice relative
to their block I/O weight. A higher weight means more I/O
bandwidth, a lower weight means less.
While StartupIOWeight= applies to the startup and shutdown phases
of the system, IOWeight= applies to the later runtime of the
system, and if the former is not set also to the startup and
shutdown phases. This allows prioritizing specific services at
boot-up and shutdown differently than during runtime.
IODeviceWeight=device weight
This setting controls the io controller in the unified hierarchy.
Set the per-device overall block I/O weight for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a space-separated pair of a file path and a weight
value to specify the device specific weight value, between 1 and
10000. (Example: "/dev/sda 1000"). The file path may be specified
as path to a block device node or as any other file, in which case
the backing block device of the file system of the file is
determined. This controls the "io.weight" control group attribute,
which defaults to 100. Use this option multiple times to set
weights for multiple devices. For details about this control group
attribute, see IO Interface Files[7].
The specified device node should reference a block device that has
an I/O scheduler associated, i.e. should not refer to partition or
loopback block devices, but to the originating, physical device.
When a path to a regular file or directory is specified it is
attempted to discover the correct originating device backing the
file system of the specified path. This works correctly only for
simpler cases, where the file system is directly placed on a
partition or physical block device, or where simple 1:1 encryption
using dm-crypt/LUKS is used. This discovery does not cover complex
storage and in particular RAID and volume management storage
devices.
IOReadBandwidthMax=device bytes, IOWriteBandwidthMax=device bytes
These settings control the io controller in the unified hierarchy.
Set the per-device overall block I/O bandwidth maximum limit for
the executed processes, if the unified control group hierarchy is
used on the system. This limit is not work-conserving and the
executed processes are not allowed to use more even if the device
has idle capacity. Takes a space-separated pair of a file path and
a bandwidth value (in bytes per second) to specify the device
specific bandwidth. The file path may be a path to a block device
node, or as any other file in which case the backing block device
of the file system of the file is used. If the bandwidth is
suffixed with K, M, G, or T, the specified bandwidth is parsed as
Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to the
base of 1000. (Example:
"/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This
controls the "io.max" control group attributes. Use this option
multiple times to set bandwidth limits for multiple devices. For
details about this control group attribute, see IO Interface
Files[7].
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IOReadIOPSMax=device IOPS, IOWriteIOPSMax=device IOPS
These settings control the io controller in the unified hierarchy.
Set the per-device overall block I/O IOs-Per-Second maximum limit
for the executed processes, if the unified control group hierarchy
is used on the system. This limit is not work-conserving and the
executed processes are not allowed to use more even if the device
has idle capacity. Takes a space-separated pair of a file path and
an IOPS value to specify the device specific IOPS. The file path
may be a path to a block device node, or as any other file in which
case the backing block device of the file system of the file is
used. If the IOPS is suffixed with K, M, G, or T, the specified
IOPS is parsed as KiloIOPS, MegaIOPS, GigaIOPS, or TeraIOPS,
respectively, to the base of 1000. (Example:
"/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This
controls the "io.max" control group attributes. Use this option
multiple times to set IOPS limits for multiple devices. For details
about this control group attribute, see IO Interface Files[7].
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IODeviceLatencyTargetSec=device target
This setting controls the io controller in the unified hierarchy.
Set the per-device average target I/O latency for the executed
processes, if the unified control group hierarchy is used on the
system. Takes a file path and a timespan separated by a space to
specify the device specific latency target. (Example: "/dev/sda
25ms"). The file path may be specified as path to a block device
node or as any other file, in which case the backing block device
of the file system of the file is determined. This controls the
"io.latency" control group attribute. Use this option multiple
times to set latency target for multiple devices. For details about
this control group attribute, see IO Interface Files[7].
Implies "IOAccounting=yes".
These settings are supported only if the unified control group
hierarchy is used.
Similar restrictions on block device discovery as for
IODeviceWeight= apply, see above.
IPAccounting=
Takes a boolean argument. If true, turns on IPv4 and IPv6 network
traffic accounting for packets sent or received by the unit. When
this option is turned on, all IPv4 and IPv6 sockets created by any
process of the unit are accounted for.
When this option is used in socket units, it applies to all IPv4
and IPv6 sockets associated with it (including both listening and
connection sockets where this applies). Note that for
socket-activated services, this configuration setting and the
accounting data of the service unit and the socket unit are kept
separate, and displayed separately. No propagation of the setting
and the collected statistics is done, in either direction.
Moreover, any traffic sent or received on any of the socket unit's
sockets is accounted to the socket unit — and never to the service
unit it might have activated, even if the socket is used by it.
The system default for this setting may be controlled with
DefaultIPAccounting= in systemd-system.conf(5).
Note that this functionality is currently only available for system
services, not for per-user services.
IPAddressAllow=ADDRESS[/PREFIXLENGTH]...,
IPAddressDeny=ADDRESS[/PREFIXLENGTH]...
Turn on network traffic filtering for IP packets sent and received
over AF_INET and AF_INET6 sockets. Both directives take a space
separated list of IPv4 or IPv6 addresses, each optionally suffixed
with an address prefix length in bits after a "/" character. If the
suffix is omitted, the address is considered a host address, i.e.
the filter covers the whole address (32 bits for IPv4, 128 bits for
IPv6).
The access lists configured with this option are applied to all
sockets created by processes of this unit (or in the case of socket
units, associated with it). The lists are implicitly combined with
any lists configured for any of the parent slice units this unit
might be a member of. By default both access lists are empty. Both
ingress and egress traffic is filtered by these settings. In case
of ingress traffic the source IP address is checked against these
access lists, in case of egress traffic the destination IP address
is checked. The following rules are applied in turn:
• Access is granted when the checked IP address matches an entry
in the IPAddressAllow= list.
• Otherwise, access is denied when the checked IP address matches
an entry in the IPAddressDeny= list.
• Otherwise, access is granted.
In order to implement an allow-listing IP firewall, it is
recommended to use a IPAddressDeny=any setting on an upper-level
slice unit (such as the root slice -.slice or the slice containing
all system services system.slice – see systemd.special(7) for
details on these slice units), plus individual per-service
IPAddressAllow= lines permitting network access to relevant
services, and only them.
Note that for socket-activated services, the IP access list
configured on the socket unit applies to all sockets associated
with it directly, but not to any sockets created by the ultimately
activated services for it. Conversely, the IP access list
configured for the service is not applied to any sockets passed
into the service via socket activation. Thus, it is usually a good
idea to replicate the IP access lists on both the socket and the
service unit. Nevertheless, it may make sense to maintain one list
more open and the other one more restricted, depending on the
usecase.
If these settings are used multiple times in the same unit the
specified lists are combined. If an empty string is assigned to
these settings the specific access list is reset and all previous
settings undone.
In place of explicit IPv4 or IPv6 address and prefix length
specifications a small set of symbolic names may be used. The
following names are defined:
Table 1. Special address/network names
┌──────────────┬─────────────────────┬─────────────────────┐
│Symbolic Name │ Definition │ Meaning │
├──────────────┼─────────────────────┼─────────────────────┤
│any │ 0.0.0.0/0 ::/0 │ Any host │
├──────────────┼─────────────────────┼─────────────────────┤
│localhost │ 127.0.0.0/8 ::1/128 │ All addresses on │
│ │ │ the local loopback │
├──────────────┼─────────────────────┼─────────────────────┤
│link-local │ 169.254.0.0/16 │ All link-local IP │
│ │ fe80::/64 │ addresses │
├──────────────┼─────────────────────┼─────────────────────┤
│multicast │ 224.0.0.0/4 │ All IP multicasting │
│ │ ff00::/8 │ addresses │
└──────────────┴─────────────────────┴─────────────────────┘
Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will have
no effect in that case. If compatibility with such systems is
desired it is hence recommended to not exclusively rely on them for
IP security.
IPIngressFilterPath=BPF_FS_PROGRAM_PATH,
IPEgressFilterPath=BPF_FS_PROGRAM_PATH
Add custom network traffic filters implemented as BPF programs,
applying to all IP packets sent and received over AF_INET and
AF_INET6 sockets. Takes an absolute path to a pinned BPF program in
the BPF virtual filesystem (/sys/fs/bpf/).
The filters configured with this option are applied to all sockets
created by processes of this unit (or in the case of socket units,
associated with it). The filters are loaded in addition to filters
any of the parent slice units this unit might be a member of as
well as any IPAddressAllow= and IPAddressDeny= filters in any of
these units. By default there are no filters specified.
If these settings are used multiple times in the same unit all the
specified programs are attached. If an empty string is assigned to
these settings the program list is reset and all previous specified
programs ignored.
If the path BPF_FS_PROGRAM_PATH in IPIngressFilterPath= assignment
is already being handled by BPFProgram= ingress hook, e.g.
BPFProgram=ingress:BPF_FS_PROGRAM_PATH, the assignment will be
still considered valid and the program will be attached to a
cgroup. Same for IPEgressFilterPath= path and egress hook.
Note that for socket-activated services, the IP filter programs
configured on the socket unit apply to all sockets associated with
it directly, but not to any sockets created by the ultimately
activated services for it. Conversely, the IP filter programs
configured for the service are not applied to any sockets passed
into the service via socket activation. Thus, it is usually a good
idea, to replicate the IP filter programs on both the socket and
the service unit, however it often makes sense to maintain one
configuration more open and the other one more restricted,
depending on the usecase.
Note that these settings might not be supported on some systems
(for example if eBPF control group support is not enabled in the
underlying kernel or container manager). These settings will fail
the service in that case. If compatibility with such systems is
desired it is hence recommended to attach your filter manually
(requires Delegate=yes) instead of using this setting.
BPFProgram=type:program-path
Add a custom cgroup BPF program.
BPFProgram= allows attaching BPF hooks to the cgroup of a systemd
unit. (This generalizes the functionality exposed via
IPEgressFilterPath= for egress and IPIngressFilterPath= for
ingress.) Cgroup-bpf hooks in the form of BPF programs loaded to
the BPF filesystem are attached with cgroup-bpf attach flags
determined by the unit. For details about attachment types and
flags see
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/include/uapi/linux/bpf.h.
For general BPF documentation please refer to
https://docs.kernel.org/bpf/index.html.
The specification of BPF program consists of a type followed by a
program-path with ":" as the separator: type:program-path.
type is the string name of BPF attach type also used in bpftool.
type can be one of egress, ingress, sock_create, sock_ops, device,
bind4, bind6, connect4, connect6, post_bind4, post_bind6, sendmsg4,
sendmsg6, sysctl, recvmsg4, recvmsg6, getsockopt, setsockopt.
Setting BPFProgram= to an empty value makes previous assignments
ineffective.
Multiple assignments of the same type:program-path value have the
same effect as a single assignment: the program with the path
program-path will be attached to cgroup hook type just once.
If BPF egress pinned to program-path path is already being handled
by IPEgressFilterPath=, BPFProgram= assignment will be considered
valid and BPFProgram= will be attached to a cgroup. Similarly for
ingress hook and IPIngressFilterPath= assignment.
BPF programs passed with BPFProgram= are attached to the cgroup of
a unit with BPF attach flag multi, that allows further attachments
of the same type within cgroup hierarchy topped by the unit cgroup.
Examples:
BPFProgram=egress:/sys/fs/bpf/egress-hook
BPFProgram=bind6:/sys/fs/bpf/sock-addr-hook
SocketBindAllow=bind-rule, SocketBindDeny=bind-rule
Configures restrictions on the ability of unit processes to invoke
bind(2) on a socket. Both allow and deny rules may defined that
restrict which addresses a socket may be bound to.
bind-rule describes socket properties such as address-family,
transport-protocol and ip-ports.
bind-rule := { [address-family:][transport-protocol:][ip-ports] |
any }
address-family := { ipv4 | ipv6 }
transport-protocol := { tcp | udp }
ip-ports := { ip-port | ip-port-range }
An optional address-family expects ipv4 or ipv6 values. If not
specified, a rule will be matched for both IPv4 and IPv6 addresses
and applied depending on other socket fields, e.g.
transport-protocol, ip-port.
An optional transport-protocol expects tcp or udp transport
protocol names. If not specified, a rule will be matched for any
transport protocol.
An optional ip-port value must lie within 1...65535 interval
inclusively, i.e. dynamic port 0 is not allowed. A range of
sequential ports is described by ip-port-range :=
ip-port-low-ip-port-high, where ip-port-low is smaller than or
equal to ip-port-high and both are within 1...65535 inclusively.
A special value any can be used to apply a rule to any address
family, transport protocol and any port with a positive value.
To allow multiple rules assign SocketBindAllow= or SocketBindDeny=
multiple times. To clear the existing assignments pass an empty
SocketBindAllow= or SocketBindDeny= assignment.
For each of SocketBindAllow= and SocketBindDeny=, maximum allowed
number of assignments is 128.
• Binding to a socket is allowed when a socket address matches an
entry in the SocketBindAllow= list.
• Otherwise, binding is denied when the socket address matches an
entry in the SocketBindDeny= list.
• Otherwise, binding is allowed.
The feature is implemented with cgroup/bind4 and cgroup/bind6
cgroup-bpf hooks.
Note that these settings apply to any bind(2) system call
invocation by the unit processes, regardless in which network
namespace they are placed. Or in other words: changing the network
namespace is not a suitable mechanism for escaping these
restrictions on bind().
Examples:
...
# Allow binding IPv6 socket addresses with a port greater than or equal to 10000.
[Service]
SocketBindAllow=ipv6:10000-65535
SocketBindDeny=any
...
# Allow binding IPv4 and IPv6 socket addresses with 1234 and 4321 ports.
[Service]
SocketBindAllow=1234
SocketBindAllow=4321
SocketBindDeny=any
...
# Deny binding IPv6 socket addresses.
[Service]
SocketBindDeny=ipv6
...
# Deny binding IPv4 and IPv6 socket addresses.
[Service]
SocketBindDeny=any
...
# Allow binding only over TCP
[Service]
SocketBindAllow=tcp
SocketBindDeny=any
...
# Allow binding only over IPv6/TCP
[Service]
SocketBindAllow=ipv6:tcp
SocketBindDeny=any
...
# Allow binding ports within 10000-65535 range over IPv4/UDP.
[Service]
SocketBindAllow=ipv4:udp:10000-65535
SocketBindDeny=any
...
RestrictNetworkInterfaces=
Takes a list of space-separated network interface names. This
option restricts the network interfaces that processes of this unit
can use. By default processes can only use the network interfaces
listed (allow-list). If the first character of the rule is "~", the
effect is inverted: the processes can only use network interfaces
not listed (deny-list).
This option can appear multiple times, in which case the network
interface names are merged. If the empty string is assigned the set
is reset, all prior assignments will have not effect.
If you specify both types of this option (i.e. allow-listing and
deny-listing), the first encountered will take precedence and will
dictate the default action (allow vs deny). Then the next
occurrences of this option will add or delete the listed network
interface names from the set, depending of its type and the default
action.
The loopback interface ("lo") is not treated in any special way,
you have to configure it explicitly in the unit file.
Example 1: allow-list
RestrictNetworkInterfaces=eth1
RestrictNetworkInterfaces=eth2
Programs in the unit will be only able to use the eth1 and eth2
network interfaces.
Example 2: deny-list
RestrictNetworkInterfaces=~eth1 eth2
Programs in the unit will be able to use any network interface but
eth1 and eth2.
Example 3: mixed
RestrictNetworkInterfaces=eth1 eth2
RestrictNetworkInterfaces=~eth1
Programs in the unit will be only able to use the eth2 network
interface.
DeviceAllow=
Control access to specific device nodes by the executed processes.
Takes two space-separated strings: a device node specifier followed
by a combination of r, w, m to control reading, writing, or
creation of the specific device nodes by the unit (mknod),
respectively. This functionality is implemented using eBPF
filtering.
When access to all physical devices should be disallowed,
PrivateDevices= may be used instead. See systemd.exec(5).
The device node specifier is either a path to a device node in the
file system, starting with /dev/, or a string starting with either
"char-" or "block-" followed by a device group name, as listed in
/proc/devices. The latter is useful to allow-list all current and
future devices belonging to a specific device group at once. The
device group is matched according to filename globbing rules, you
may hence use the "*" and "?" wildcards. (Note that such globbing
wildcards are not available for device node path specifications!)
In order to match device nodes by numeric major/minor, use device
node paths in the /dev/char/ and /dev/block/ directories. However,
matching devices by major/minor is generally not recommended as
assignments are neither stable nor portable between systems or
different kernel versions.
Examples: /dev/sda5 is a path to a device node, referring to an ATA
or SCSI block device. "char-pts" and "char-alsa" are specifiers
for all pseudo TTYs and all ALSA sound devices, respectively.
"char-cpu/*" is a specifier matching all CPU related device groups.
Note that allow lists defined this way should only reference device
groups which are resolvable at the time the unit is started. Any
device groups not resolvable then are not added to the device allow
list. In order to work around this limitation, consider extending
service units with a pair of After=modprobe@xyz.service and
Wants=modprobe@xyz.service lines that load the necessary kernel
module implementing the device group if missing. Example:
...
[Unit]
Wants=modprobe@loop.service
After=modprobe@loop.service
[Service]
DeviceAllow=block-loop
DeviceAllow=/dev/loop-control
...
DevicePolicy=auto|closed|strict
Control the policy for allowing device access:
strict
means to only allow types of access that are explicitly
specified.
closed
in addition, allows access to standard pseudo devices including
/dev/null, /dev/zero, /dev/full, /dev/random, and /dev/urandom.
auto
in addition, allows access to all devices if no explicit
DeviceAllow= is present. This is the default.
Slice=
The name of the slice unit to place the unit in. Defaults to
system.slice for all non-instantiated units of all unit types
(except for slice units themselves see below). Instance units are
by default placed in a subslice of system.slice that is named after
the template name.
This option may be used to arrange systemd units in a hierarchy of
slices each of which might have resource settings applied.
For units of type slice, the only accepted value for this setting
is the parent slice. Since the name of a slice unit implies the
parent slice, it is hence redundant to ever set this parameter
directly for slice units.
Special care should be taken when relying on the default slice
assignment in templated service units that have
DefaultDependencies=no set, see systemd.service(5), section
"Default Dependencies" for details.
Delegate=
Turns on delegation of further resource control partitioning to
processes of the unit. Units where this is enabled may create and
manage their own private subhierarchy of control groups below the
control group of the unit itself. For unprivileged services (i.e.
those using the User= setting) the unit's control group will be
made accessible to the relevant user.
When enabled the service manager will refrain from manipulating
control groups or moving processes below the unit's control group,
so that a clear concept of ownership is established: the control
group tree at the level of the unit's control group and above (i.e.
towards the root control group) is owned and managed by the service
manager of the host, while the control group tree below the unit's
control group is owned and managed by the unit itself.
Takes either a boolean argument or a (possibly empty) list of
control group controller names. If true, delegation is turned on,
and all supported controllers are enabled for the unit, making them
available to the unit's processes for management. If false,
delegation is turned off entirely (and no additional controllers
are enabled). If set to a list of controllers, delegation is turned
on, and the specified controllers are enabled for the unit.
Assigning the empty string will enable delegation, but reset the
list of controllers, and all assignments prior to this will have no
effect. Note that additional controllers other than the ones
specified might be made available as well, depending on
configuration of the containing slice unit or other units contained
in it. Defaults to false.
Note that controller delegation to less privileged code is only
safe on the unified control group hierarchy. Accordingly, access to
the specified controllers will not be granted to unprivileged
services on the legacy hierarchy, even when requested.
The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.
Not all of these controllers are available on all kernels however,
and some are specific to the unified hierarchy while others are
specific to the legacy hierarchy. Also note that the kernel might
support further controllers, which aren't covered here yet as
delegation is either not supported at all for them or not defined
cleanly.
Note that because of the hierarchical nature of cgroup hierarchy,
any controllers that are delegated will be enabled for the parent
and sibling units of the unit with delegation.
For further details on the delegation model consult Control Group
APIs and Delegation[8].
DisableControllers=
Disables controllers from being enabled for a unit's children. If a
controller listed is already in use in its subtree, the controller
will be removed from the subtree. This can be used to avoid
configuration in child units from being able to implicitly or
explicitly enable a controller. Defaults to empty.
Multiple controllers may be specified, separated by spaces. You may
also pass DisableControllers= multiple times, in which case each
new instance adds another controller to disable. Passing
DisableControllers= by itself with no controller name present
resets the disabled controller list.
It may not be possible to disable a controller after units have
been started, if the unit or any child of the unit in question
delegates controllers to its children, as any delegated subtree of
the cgroup hierarchy is unmanaged by systemd.
The following controller names may be specified: cpu, cpuacct,
cpuset, io, blkio, memory, devices, pids, bpf-firewall, and
bpf-devices.
ManagedOOMSwap=auto|kill, ManagedOOMMemoryPressure=auto|kill
Specifies how systemd-oomd.service(8) will act on this unit's
cgroups. Defaults to auto.
When set to kill, the unit becomes a candidate for monitoring by
systemd-oomd. If the cgroup passes the limits set by oomd.conf(5)
or the unit configuration, systemd-oomd will select a descendant
cgroup and send SIGKILL to all of the processes under it. You can
find more details on candidates and kill behavior at systemd-
oomd.service(8) and oomd.conf(5).
Setting either of these properties to kill will also result in
After= and Wants= dependencies on systemd-oomd.service unless
DefaultDependencies=no.
When set to auto, systemd-oomd will not actively use this cgroup's
data for monitoring and detection. However, if an ancestor cgroup
has one of these properties set to kill, a unit with auto can still
be a candidate for systemd-oomd to terminate.
ManagedOOMMemoryPressureLimit=
Overrides the default memory pressure limit set by oomd.conf(5) for
this unit (cgroup). Takes a percentage value between 0% and 100%,
inclusive. This property is ignored unless
ManagedOOMMemoryPressure=kill. Defaults to 0%, which means to use
the default set by oomd.conf(5).
ManagedOOMPreference=none|avoid|omit
Allows deprioritizing or omitting this unit's cgroup as a candidate
when systemd-oomd needs to act. Requires support for extended
attributes (see xattr(7)) in order to use avoid or omit.
When calculating candidates to relieve swap usage, systemd-oomd
will only respect these extended attributes if the unit's cgroup is
owned by root.
When calculating candidates to relieve memory pressure,
systemd-oomd will only respect these extended attributes if the
unit's cgroup owner, and the owner of the monitored ancestor cgroup
are the same. For example, if systemd-oomd is calculating
candidates for -.slice, then extended attributes set on descendants
of /user.slice/user-1000.slice/user@1000.service/ will be ignored
because the descendants are owned by UID 1000, and -.slice is owned
by UID 0. But, if calculating candidates for
/user.slice/user-1000.slice/user@1000.service/, then extended
attributes set on the descendants would be respected.
If this property is set to avoid, the service manager will convey
this to systemd-oomd, which will only select this cgroup if there
are no other viable candidates.
If this property is set to omit, the service manager will convey
this to systemd-oomd, which will ignore this cgroup as a candidate
and will not perform any actions on it.
It is recommended to use avoid and omit sparingly, as it can
adversely affect systemd-oomd's kill behavior. Also note that these
extended attributes are not applied recursively to cgroups under
this unit's cgroup.
Defaults to none which means systemd-oomd will rank this unit's
cgroup as defined in systemd-oomd.service(8) and oomd.conf(5).
HISTORY
systemd 252
Options for controlling the Legacy Control Group Hierarchy (Control
Groups version 1[9] are now fully deprecated: CPUShares=weight,
StartupCPUShares=weight, MemoryLimit=bytes, BlockIOAccounting=,
BlockIOWeight=weight, StartupBlockIOWeight=weight,
BlockIODeviceWeight=device weight, BlockIOReadBandwidth=device
bytes, BlockIOWriteBandwidth=device bytes. Please switch to the
unified cgroup hierarchy.
SEE ALSO
systemd(1), systemd-system.conf(5), systemd.unit(5),
systemd.service(5), systemd.slice(5), systemd.scope(5),
systemd.socket(5), systemd.mount(5), systemd.swap(5), systemd.exec(5),
systemd.directives(7), systemd.special(7), systemd-oomd.service(8), The
documentation for control groups and specific controllers in the Linux
kernel: Control Groups v2[2].
NOTES
1. New Control Group Interfaces
https://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface
2. Control Groups v2
https://docs.kernel.org/admin-guide/cgroup-v2.html
3. CFS Scheduler
https://docs.kernel.org/scheduler/sched-design-CFS.html
4. CFS Bandwidth Control
https://docs.kernel.org/scheduler/sched-bwc.html
5. Memory Interface Files
https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files
6. pids controller
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#pid
7. IO Interface Files
https://docs.kernel.org/admin-guide/cgroup-v2.html#io-interface-files
8. Control Group APIs and Delegation
https://systemd.io/CGROUP_DELEGATION
9. Control Groups version 1
https://docs.kernel.org/admin-guide/cgroup-v1/index.html
systemd 252 SYSTEMD.RESOURCE-CONTROL(5)
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