In scrutinizing the journal overhead of `systemctl status $service`
it became apparent that the matching engine was performing the unit
matches on every journal in my system, even ones containing nothing
relevant to the current boot.
This seemed strange and likely suboptimal to me, since there's likely
far more unit data to rifle through than boot IDs in any given
journal. The _BOOT_ID match seemed like it should be serving as an
early exit match on irrelevant journals, but that wasn't what seemed
to be happening.
As a quick experiment to see if I could get the _BOOT_ID match to be
something along the lines of a higher priority when matching, and try
early exit on these unrelated journals, I moved add_match_this_boot()
to after the unit match adds, inserting a conjunction between them.
The end result seems to be a very substantial performance gain in my
simple uncached tests, and I still get the expected journal output
from the `systemctl status $service` command:
----------------------------------------------------------------------
Unmodified systemctl times:
root@localhost:/# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/# time systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static; vendor preset: enabled)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.695s
user 0m0.005s
sys 0m0.043s
root@localhost:/# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/# time systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static; vendor preset: enabled)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.696s
user 0m0.003s
sys 0m0.046s
root@localhost:/# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/# time systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static; vendor preset: enabled)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.694s
user 0m0.006s
sys 0m0.041s
----------------------------------------------------------------------
Modified systemctl including this commit:
root@localhost:/home/vc/gh/systemd/build# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/home/vc/gh/systemd/build# time ./systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
TriggeredBy: ● dbus.socket
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.168s
user 0m0.003s
sys 0m0.016s
root@localhost:/home/vc/gh/systemd/build# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/home/vc/gh/systemd/build# time ./systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
TriggeredBy: ● dbus.socket
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.167s
user 0m0.005s
sys 0m0.013s
root@localhost:/home/vc/gh/systemd/build# echo 2 > /proc/sys/vm/drop_caches
root@localhost:/home/vc/gh/systemd/build# time ./systemctl --no-pager status dbus
● dbus.service - D-Bus System Message Bus
Loaded: loaded (/lib/systemd/system/dbus.service; static)
Active: active (running) since Sun 2020-10-25 17:03:05 PDT; 1 day 6h ago
TriggeredBy: ● dbus.socket
Docs: man:dbus-daemon(1)
Main PID: 572 (dbus-daemon)
Memory: 2.8M
CPU: 110ms
CGroup: /system.slice/dbus.service
└─572 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
Oct 25 17:03:05 localhost systemd[1]: Started D-Bus System Message Bus.
Oct 25 17:06:26 localhost dbus[572]: [system] Activating via systemd: service name='org.freedesktop.machine1' unit='dbus-org.freedesktop.machine1.service'
Oct 25 17:06:26 localhost dbus[572]: [system] Successfully activated service 'org.freedesktop.machine1'
real 0m0.170s
user 0m0.005s
sys 0m0.014s
This adds minimal support for RFC5001 NSID to the stub resolver. This
useful to identify systemd-resolved when talking to the stub resolver,
and distuingishing the packets resolved answers itself (where NSID is
now set) from those which it proxies 1:1 upstream (where NSID will not
be set, or set to whatever the upstream server has it set to).
The NSID chosen consist of two parts:
1. The first part is derived from /etc/machine-id and identifies the
resolved instance in a stable way.
2. The second part is the fixed string ".resolved.systemd.io".
This thus maybe used for a veriety of checks:
a. Am I talking to a resolved stub?
b. Am I talking to the same stub as last time?
c. Am I talking to the local resolved?
Given that the first part leaks the identity of the system in away two
protections are in place:
I) The NSID is only included on the main stub, not the extra stub. The
main stub has with a TTL of 1 and other protections a lot of safety
in place that the datagrams never leave the local system, thus the
identifying info is only accessible to the local system — but
/etc/machine-id is accessible to local software anyway.
II) The NSID is hashed from /etc/machine-id in a non-invertable way, so
that the machine ID itself isn't leaked, but only an identifier
derived from it.
Example dig run:
```
$ dig +nsid localhost @127.0.0.53
; <<>> DiG 9.11.23-RedHat-9.11.23-1.fc33 <<>> +nsid localhost @127.0.0.53
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46917
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
; NSID: 35 33 64 34 61 34 66 63 32 31 32 65 34 31 61 30 39 66 30 39 65 33 32 34 63 64 64 38 30 36 32 33 2e 72 65 73 6f 6c 76 65 64 2e 73 79 73 74 65 6d 64 2e 69 6f ("53d4a4fc212e41a09f09e324cdd80623.resolved.systemd.io")
;; QUESTION SECTION:
;localhost. IN A
;; ANSWER SECTION:
localhost. 0 IN A 127.0.0.1
;; Query time: 0 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Do Nov 12 20:57:16 CET 2020
;; MSG SIZE rcvd: 110
```
Taking a stab at implementing #14479.
Add {Condition,Assert}CPUFeature to `systemd-analyze` & friends. Implement it
by executing the CPUID instruction. Add tables for common x86/i386
features.
Tested via unit tests + checked that commands such as:
```bash
systemd-analyze condition 'AssertCPUFeature = rdrand'
```
Succeed as expected and that commands such as
```bash
systemd-analyze condition 'AssertCPUFeature = foobar'
```
Fail as expected. Finally, I have amended the `systemd.unit` manual page
with the new condition and the list of all currently supported flags.
The existing set_offline() short-circuit erroneously included
when f->archive was true and header->state was STATE_OFFLINE.
This commit makes the short-circuit f->archive aware, so it will
only catch scenarios where there's not an offlining in progress
and the header state matches the target state of either archived
or offline.
Fixes https://github.com/systemd/systemd/issues/17770
It's better for users if programs don't do "significant" things too easily, and
should be especially conservative when called without any arguments whatsoever.
So far systemd would would try to launch itself as a user manager and fail on
some cgroup permission stuff. systemd --user is run execlusively from user@.service
and there we call it with --user. Calls to the binary without any arguments as
non-pid1 are almost always a mistake.
https://github.com/systemd/systemd/issues/18419#issuecomment-779422571
4acf0cfd2f ("logind: check PolicyKit before allowing VT switch") broke
the ability to write user sessions that run graphical sessions (e.g.
weston/X11). This was partially amended in 19bb87fbfa ("login: allow
non-console sessions to change vt") by changing the default PolicyKit
policy so that non-root users with a session are again allowed to switch
the VT. This makes the policy when PolKit is not enabled (as on many
embedded systems) closer the default PolKit policy and allows launching
graphical sessions as a non-root user.
Closes#17473
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Use the right FD, and do a fd_reopen instead of a dup, since the
latter will still share the internal pointer which then gets
moved by FOREACH_DIRENT, affecting the caller's FD.
Let's unify some code, and add a common implementation of a function
that checks whether we have tried all DNS servers yet, and retries the
transaction if we don't. We already use this same code twice. Let's use
it at some other places too now — basically all cases where we switch to
a new server — with the one case of packet loss, where we too switch
servers, but don#t care how many times we already tried to switch.
This adjusts our feature level handling: when DNSSEC strict mode is on,
let's never lower the feature level below the lowest DNSSEC mode.
Also, when asking whether DNSSEC is supproted, always say yes in strict
mode. This means that error reporting about transactions that fail
because of missing DNSSEC RRs will not report "incompatible-server" but
instead "missing-signature" or suchlike.
The main difference here is that DNSSEC failures become local to a
transaction, instead of propagating into the feature level we reuse for
future transactions. This is beneficial with routers that implement
"mostly a DNS proxy", i.e. that propagate most DNS requests 1:1 to their
upstream servers, but synthesize local answers for a select few domains.
For example, AVM Fritz!Boxes operate that way: they proxy most traffic
1:1 upstream in an DNSSEC-compatible fashion, but synthesize the
"fritz.box" locally, so that it can be used to configure the router.
This local domain cannot be DNSSEC verified, it comes without
signatures. Previously this would mean once that domain was resolved
feature level would be downgraded, and we'd thus fail all future DNSSEC
attempts. With this change, the immediate lookup for "fritz.box" will
fail validation, but for all other unrelated future ones that comes
without prejudice.
(While we are at it, also make a couple of other downgrade paths a bit
tighter.)
Fixes: #10570#14435#6490
The levels have an order, but the order is sometimes a bit arbitrary.
Hence add simple macros to check for specific features and use those, so
that the ordering leaks a bit less into all files.
So far we didn't really handle the case where we can't parse a reply
packet. Since this apparently happens in real-life though, let's add
some minimal logic, to downgrade/restart if we see this.
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Vito Caputo
Lennart Poettering
Hans de Goede
Giedrius Statkevičius
Benjamin Robin
Joshua Watt
Luca Boccassi
heretoenhance