Unfortunately we can't escape $ when ':' is used to prohibit variable expansion:
ExecStart=:echo $$
is not the same as
ExecStart=:echo $
This just adds the functionality and the unittests, without using it anywhere
for real yet.
Our escaping of '$' is '$$', not '\$'. We would write unit files that
were not valid:
$ systemd-run --user bash -c 'echo $$; sleep 1000'
Running as unit: run-r1c7c45b5b69f487c86ae205e12100808.service
$ systemctl cat --user run-r1c7c45b5b69f487c86ae205e12100808
# /run/user/1000/systemd/transient/run-r1c7c45b5b69f487c86ae205e12100808.service
...
ExecStart="/usr/bin/bash" "-c" "echo \$\$\; sleep 1000"
$ systemd-analyze verify /run/user/1000/systemd/transient/run-r1c7c45b5b69f487c86ae205e12100808.service
/run/user/1000/systemd/transient/run-r1c7c45b5b69f487c86ae205e12100808.service:7:
Ignoring unknown escape sequences: "echo \$\$\; sleep 1000"
Similarly, ';' cannot be escaped as '\;'. Only a handful of characters
listed in "Supported escapes" is allowed.
Escaping of "'" can be done, but it's not useful because we use double quotes
around the string anyway whenever we do escaping.
unit_write_setting() is called all over the place. In a great majority of
places we write either fixed strings or something that we generate ourselves,
so no escaping or quoting is needed. (And it's not allowed, e.g.
'Type="oneshot"' would not work.) But if we forgot to add escaping or quoting
for a free-style string, it would probably allow writing a unit file that would
be read completely wrong. I looked over various places where
unit_write_setting() is called, and I couldn't find any place where
quoting/escaping was forgotten. But trying to figure out the full
ramifications of this change is not easy.
__builtin_popcount() is a bit of a mouthful, so let's provide a helper.
Using _Generic has the advantage that if a type other then the ones on
the list is given, compilation will fail. This is nice, because if by any
change we pass a wider type, it is rejected immediately instead of being
truncated.
log.h is also needed. It is included transitively, but let's include it
directly.
macro.h is *not* needed.
Normal users do not have permissions to access /proc/1/root, so
'systemd-detect-virt -r' fails, but the output, even at debug level
is cryptic:
$ SYSTEMD_LOG_LEVEL=debug build/systemd-detect-virt -r
Failed to check for chroot() environment: Permission denied
Let's make this a bit easier to figure out:
$ SYSTEMD_LOG_LEVEL=debug build/systemd-detect-virt -r
Cannot stat /proc/1/root: Permission denied
Failed to check for chroot() environment: Permission denied
I looked over other users of files_same(), and I think in general the message
at debug level is OK for them too.
Meta's resource control demo project[0] includes a benchmark tool that can
be used to calculate the best iocost solutions for a given SSD.
[0]: https://github.com/facebookexperimental/resctl-demo
A project[1] has now been started to create a publicly available database
of results that can be used to apply them automatically.
[1]: https://github.com/iocost-benchmark/iocost-benchmarks
This change adds a new tool that gets triggered by a udev rule for any
block device and queries the hwdb for known solutions. The format for
the hwdb file that is currently generated by the github action looks like
this:
# This file was auto-generated on Tue, 23 Aug 2022 13:03:57 +0000.
# From the following commit:
# https://github.com/iocost-benchmark/iocost-benchmarks/commit/ca82acfe93c40f21d3b513c055779f43f1126f88
#
# Match key format:
# block:<devpath>:name:<model name>:
# 12 points, MOF=[1.346,1.346], aMOF=[1.249,1.249]
block:*:name:HFS256GD9TNG-62A0A:fwver:*:
IOCOST_SOLUTIONS=isolation isolated-bandwidth bandwidth naive
IOCOST_MODEL_ISOLATION=rbps=1091439492 rseqiops=52286 rrandiops=63784 wbps=192329466 wseqiops=12309 wrandiops=16119
IOCOST_QOS_ISOLATION=rpct=0.00 rlat=8807 wpct=0.00 wlat=59023 min=100.00 max=100.00
IOCOST_MODEL_ISOLATED_BANDWIDTH=rbps=1091439492 rseqiops=52286 rrandiops=63784 wbps=192329466 wseqiops=12309 wrandiops=16119
IOCOST_QOS_ISOLATED_BANDWIDTH=rpct=0.00 rlat=8807 wpct=0.00 wlat=59023 min=100.00 max=100.00
IOCOST_MODEL_BANDWIDTH=rbps=1091439492 rseqiops=52286 rrandiops=63784 wbps=192329466 wseqiops=12309 wrandiops=16119
IOCOST_QOS_BANDWIDTH=rpct=0.00 rlat=8807 wpct=0.00 wlat=59023 min=100.00 max=100.00
IOCOST_MODEL_NAIVE=rbps=1091439492 rseqiops=52286 rrandiops=63784 wbps=192329466 wseqiops=12309 wrandiops=16119
IOCOST_QOS_NAIVE=rpct=99.00 rlat=8807 wpct=99.00 wlat=59023 min=75.00 max=100.00
The IOCOST_SOLUTIONS key lists the solutions available for that device
in the preferred order for higher isolation, which is a reasonable
default for most client systems. This can be overriden to choose better
defaults for custom use cases, like the various data center workloads.
The tool can also be used to query the known solutions for a specific
device or to apply a non-default solution (say, isolation or bandwidth).
Co-authored-by: Santosh Mahto <santosh.mahto@collabora.com>
getty-generator enables serial-getty@.service for virtualizer consoles
that it can find in /sys/class/tty. To make sure this works for
virtio consoles, let's make sure we load the module is loaded early
so that the /sys/class/tty/hvc0 exists before we run getty-generator.
This is the function version of STARTSWITH_SET(). We also move
STARTSWITH_SET() to string-util.h as it fits more there than in
strv.h and reimplement it using startswith_strv().
Let's avoid confusing developers and users when log messages suddenly
stop getting logged to kmsg because of ratelimiting by logging an
additional message if we start ratelimiting log messages to kmsg.
When trying to mount a partition that is encrypted without the
encryption first having been set up we want to return a
recognizable error (EUNATCH). This was broken by
80ce8580f5 which added an allowlist check
for permissible file systems first. Let's reverse the check order, so
that we get EUNATCH again, as before. (And leave EIDRM as error for the
failed allowlist check).
An overflow here (i.e. the counter reaching 2^32 within a ratelimit time
window) is not so unlikely. Let's handle this somewhat sanely
and simply stop counting, while remaining in the "limit is hit" state until
the time window has passed.
See added code comment for a longer explanation. TLDR: Linux maintains
distinct block device caches for partition and "whole" block devices,
and a simply BLKFLSBUF should make the worst confusions this causes go
away.
DHCP static leases are looked up by the client identifier as send by
the client, while configured based on MAC. As RFC 2131 states the client
identifier is an opaque key and must not be interpreted by the server
this means that DHCP clients can (/will) also use a client identifier
which is not a MAC address. One of these clients actually is
systemd-networkd which uses an RFC 4361 by default to generate the
client identifier. For these kind of DHCP clients static leases thus
don't work because of this mismatch between configuring a MAC address
but the server matching based on client identifier. This adds a fallback
to try to look up a configured static lease based on the "chaddr" of the
DHCP message as this will always contain the MAC address of the client.
Fixes#21368
If the device unit is not the head of the list saved in
Manager.devices_by_sysfs, then it is not necessary to replace the
existing hashmap entry. This should not change any behavior, just
refactoring.
The function path_prefix_root_cwd() was introduced for prefixing the
result from chaseat() with root, but
- it is named slightly generic,
- the logic is different from what chase() does.
This makes the name more explanative and specific for the result of the
chaseat(), and make the logic consistent with chase().
Fixes https://github.com/systemd/systemd/pull/27199#issuecomment-1511387731.
Follow-up for #27199.
Now, dir_fd_is_root() is heavily used in chaseat(), which is used at
various places. If the kernel is too old and /proc is not mounted, then
there is no way to get the mount ID of a directory. In that case, let's
silently skip the mount ID check.
Fixes https://github.com/systemd/systemd/pull/27299#issuecomment-1511403680.
Usually, we pass the file descriptor of the root directory to chaseat()
when `--root=` is not specified. Previously, even in such case, the
result was relative, and we need to prefix the path with "/" when we
want to pass the path to other functions that do not support dir_fd, or
log or show the path. That's inconvenient.
E.g. in logs on jammy-ppc64el in https://github.com/systemd/systemd/pull/27294:
Apr 16 17:42:50 H systemd-gpt-auto-generator[300]: Failed to dissect partition table of block device /dev/sda: No message of desired type
Apr 16 17:42:50 H (sd-execu[295]: /usr/lib/systemd/system-generators/systemd-gpt-auto-generator failed with exit status 1.
ee0e6e476e made this particular condition not an
error. But for other errnos we want to print a better message too.
dissect_loop_device_and_warn() already does this, but it always prints the
error at error level. We want to suppress some of the errors, so let's make the
print helper public and do the error suppression in the caller.
If getty-generator runs in the initrd, the corresponding tty might not
have been instantiated yet in /dev, which means a serial getty is not
spawned on it. Instead, let's instantiate the serial-getty when the
device appears so that it always gets instantiated.
This makes the bpf LSM check generic, so that we can use it elsewhere.
it also drops the caching inside it, given that bpf-lsm code in PID1
will cache it a second time a stack frame further up when it checks for
various other bpf functionality.
Running systemd with IP accounting enabled generates many bpf maps (two
per unit for accounting, another two if IPAddressAllow/Deny are used).
Systemd itself knows which maps belong to what unit and commands like
`systemctl status <unit>` can be used to query what service has which
map, but monitoring these values all the time costs 4 dbus requests
(calling the .IP{E,I}gress{Bytes,Packets} method for each unit) and
makes services like the prometheus systemd_exporter[1] somewhat slow
when doing that for every units, while less precise information could
quickly be obtained by looking directly at the maps.
Unfortunately, bpf map names are rather limited:
- only 15 characters in length (16, but last byte must be 0)
- only allows isalnum(), _ and . characters
If it wasn't for the length limit we could use the normal unit escape
functions but I've opted to just make any forbidden character into
underscores for maximum brievty -- the map prefix is also rather short:
This isn't meant as a precise mapping, but as a hint for admins who want
to look at these.
(Note there is no problem if multiple maps have the same name)
Link: https://github.com/povilasv/systemd_exporter [1]
Let's be more careful with generating error codes for (expected) error
causes.
This does not introduce new error conditions, it just changes what we
return under specific cases, to make things nicely recognizable in each
case. Most importantly this detects if fdinfo reports a pid of "-1" for
pidfds with processes that are already reaped (and thus have no PID
anymore)
None of our current users care about these error codes, but let's get
this right for the future.
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
David Tardon
Lennart Poettering
Luca Boccassi
Frantisek Sumsal
Gustavo Noronha SilvaandSantosh Mahto
Robert Meijers
Yu Watanabe
Quintin Hill
Mike Yuan
Dominique Martinet