This setting adds minimal user namespacing support to a service. When set the invoked
processes will run in their own user namespace. Only a trivial mapping will be
set up: the root user/group is mapped to root, and the user/group of the
service will be mapped to itself, everything else is mapped to nobody.
If this setting is used the service runs with no capabilities on the host, but
configurable capabilities within the service.
This setting is particularly useful in conjunction with RootDirectory= as the
need to synchronize /etc/passwd and /etc/group between the host and the service
OS tree is reduced, as only three UID/GIDs need to match: root, nobody and the
user of the service itself. But even outside the RootDirectory= case this
setting is useful to substantially reduce the attack surface of a service.
Example command to test this:
systemd-run -p PrivateUsers=1 -p User=foobar -t /bin/sh
This runs a shell as user "foobar". When typing "ps" only processes owned by
"root", by "foobar", and by "nobody" should be visible.
This adds a new boolean setting DynamicUser= to service files. If set, a new
user will be allocated dynamically when the unit is started, and released when
it is stopped. The user ID is allocated from the range 61184..65519. The user
will not be added to /etc/passwd (but an NSS module to be added later should
make it show up in getent passwd).
For now, care should be taken that the service writes no files to disk, since
this might result in files owned by UIDs that might get assigned dynamically to
a different service later on. Later patches will tighten sandboxing in order to
ensure that this cannot happen, except for a few selected directories.
A simple way to test this is:
systemd-run -p DynamicUser=1 /bin/sleep 99999
That way, we can neatly keep this in line with the new TasksMaxScale= option.
Note that we didn't release a version with MemoryLimitByPhysicalMemory= yet,
hence this change should be unproblematic without breaking API.
This adds support for a TasksMax=40% syntax for specifying values relative to
the system's configured maximum number of processes. This is useful in order to
neatly subdivide the available room for tasks within containers.
This patch renames Read{Write,Only}Directories= and InaccessibleDirectories=
to Read{Write,Only}Paths= and InaccessiblePaths=, previous names are kept
as aliases but they are not advertised in the documentation.
Renamed variables:
`read_write_dirs` --> `read_write_paths`
`read_only_dirs` --> `read_only_paths`
`inaccessible_dirs` --> `inaccessible_paths`
The unit files already accept relative, percent-based memory limit
specification, let's make sure "systemctl set-property" support this too.
Since we want the physical memory size of the destination machine to apply we
pass the percentage in a new set of properties that only exist for this
purpose, and can only be set.
New exec boolean MemoryDenyWriteExecute, when set, installs
a seccomp filter to reject mmap(2) with PAGE_WRITE|PAGE_EXEC
and mprotect(2) with PAGE_EXEC.
Recently added cgroup unified hierarchy support uses "max" in configurations
for no upper limit. While consistent with what the kernel uses for no upper
limit, it is inconsistent with what systemd uses for other controllers such as
memory or pids. There's no point in introducing another term. Update cgroup
unified hierarchy support so that "infinity" is the only term that systemd
uses for no upper limit.
On the unified hierarchy, memory controller implements three control knobs -
low, high and max which enables more useable and versatile control over memory
usage. This patch implements support for the three control knobs.
* MemoryLow, MemoryHigh and MemoryMax are added for memory.low, memory.high and
memory.max, respectively.
* As all absolute limits on the unified hierarchy use "max" for no limit, make
memory limit parse functions accept "max" in addition to "infinity" and
document "max" for the new knobs.
* Implement compatibility translation between MemoryMax and MemoryLimit.
v2:
- Fixed missing else's in config_parse_memory_limit().
- Fixed missing newline when writing out drop-ins.
- Coding style updates to use "val > 0" instead of "val".
- Minor updates to documentation.
We have to pass addresses of changes and n_changes to
bus_deserialize_and_dump_unit_file_changes(). Otherwise we are hit by
missing information (subsequent calls to unit_file_changes_add() to
not add anything).
Also prevent null pointer dereference in
bus_deserialize_and_dump_unit_file_changes() by asserting.
Fixes#3339
Currently, there are two cgroup IO limits, bandwidth max for read and write,
and they are hard-coded in various places. This is fine for two limits but IO
is expected to grow more limits - low, high and max limits for bandwidth and
IOPS - and hard-coding each limit won't make sense.
This patch replaces hard-coded limits with an array indexed by
CGroupIOLimitType and accompanying string and default value tables so that new
limits can be added trivially.
That function doesn't draw anything on it's own, just returns a string, which
sometimes is more than one character. Also remove "DRAW_" prefix from character
names, TREE_* and ARROW and BLACK_CIRCLE are unambigous on their own, don't
draw anything, and are always used as an argument to special_glyph().
Rename "DASH" to "MDASH", as there's more than one type of dash.
On the unified hierarchy, blkio controller is renamed to io and the interface
is changed significantly.
* blkio.weight and blkio.weight_device are consolidated into io.weight which
uses the standardized weight range [1, 10000] with 100 as the default value.
* blkio.throttle.{read|write}_{bps|iops}_device are consolidated into io.max.
Expansion of throttling features is being worked on to support
work-conserving absolute limits (io.low and io.high).
* All stats are consolidated into io.stats.
This patchset adds support for the new interface. As the interface has been
revamped and new features are expected to be added, it seems best to treat it
as a separate controller rather than trying to expand the blkio settings
although we might add automatic translation if only blkio settings are
specified.
* io.weight handling is mostly identical to blkio.weight[_device] handling
except that the weight range is different.
* Both read and write bandwidth settings are consolidated into
CGroupIODeviceLimit which describes all limits applicable to the device.
This makes it less painful to add new limits.
* "max" can be used to specify the maximum limit which is equivalent to no
config for max limits and treated as such. If a given CGroupIODeviceLimit
doesn't contain any non-default configs, the config struct is discarded once
the no limit config is applied to cgroup.
* lookup_blkio_device() is renamed to lookup_block_device().
Signed-off-by: Tejun Heo <htejun@fb.com>
bus_append_unit_property_assignment() was missing an argument for
sd_bus_message_append() when processing BlockIODeviceWeight leading to
segfault. Fix it.
Signed-off-by: Tejun Heo <htejun@fb.com>
It was incorrectly using cg_cpu_weight_parse() to parse BlockIOWeight. Update
it to use cg_blkio_weight_parse() instead.
Signed-off-by: Tejun Heo <htejun@fb.com>
The "resources" error is really just the generic error we return when
we hit some kind of error and we have no more appropriate error for the case to
return, for example because of some OS error.
Hence, reword the explanation and don't claim any relation to resource limits.
Admittedly, the "resources" service error is a bit of a misnomer, but I figure
it's kind of API now.
Fixes: #2716
Previously we'd have generally useful sd-bus utilities in bust-util.h,
intermixed with code that is specifically for writing clients for PID 1,
wrapping job and unit handling. Let's split the latter out and move it into
bus-unit-util.c, to make the sources a bit short and easier to grok.
This adds a new GetProcesses() bus call to the Unit object which returns an
array consisting of all PIDs, their process names, as well as their full cgroup
paths. This is then used by "systemctl status" to show the per-unit process
tree.
This has the benefit that the client-side no longer needs to access the
cgroupfs directly to show the process tree of a unit. Instead, it now uses this
new API, which means it also works if -H or -M are used correctly, as the
information from the specific host is used, and not the one from the local
system.
Fixes: #2945
David Michael