Alternative to b50f6dbe57
The commit naively returned early from socket_enter_running(), which however
is quite problematic, as the socket will be woken up over and over again
without doing a thing, until we eventually hit Poll/TriggerLimit*=.
On top of that it requires hacks to hold the start job for initrd-switch-root.service
up. Overall I doubt that is the right approach.
Let's instead hook this into our job engine, and try to activate
the service again when some other units are stopped. If all installed
jobs have been run yet we're still seeing the conflict or the manually
selected timeout is reached, fail the socket as before.
This controls the new SO_PASSRIGHTS socket option in kernel v6.16.
Note that I intentionally choose a different naming scheme than
Pass*=, since all other Pass*= options controls whether some extra
bits are attached to the message, while this one's about denying
file descriptor transfer and it feels more explicit this way.
And diverging from underlying socket option name is precedented
by Timestamping=. But happy to change it to just say PassRights=
if people disagree.
Multipath TCP (MPTCP), standardized in RFC8684 [1], is a TCP extension
that enables a TCP connection to use different paths. It allows a device
to make use of multiple interfaces at once to send and receive TCP
packets over a single MPTCP connection. MPTCP can aggregate the
bandwidth of multiple interfaces or prefer the one with the lowest
latency, it also allows a fail-over if one path is down, and the traffic
is seamlessly re-injected on other paths.
To benefit from MPTCP, both the client and the server have to support
it. Multipath TCP is a backward-compatible TCP extension that is enabled
by default on recent Linux distributions (Debian, Ubuntu, Redhat, ...).
Multipath TCP is included in the Linux kernel since version 5.6 [2]. To
use it on Linux, an application must explicitly enable it when creating
the socket:
int sd = socket(AF_INET(6), SOCK_STREAM, IPPROTO_MPTCP);
No need to change anything else in the application.
This patch allows MPTCP protocol in the Socket unit configuration. So
now, a <unit>.socket can contain this to use MPTCP instead of TCP:
[Socket]
SocketProtocol=mptcp
MPTCP support has been allowed similarly to what has been already done
to allow SCTP: just one line in core/socket.c, a very simple addition
thanks to the flexible architecture already in place.
On top of that, IPPROTO_MPTCP has also been added in the list of allowed
protocols in two other places, and in the doc. It has also been added to
the missing_network.h file, for systems with an old libc -- note that it
was also required to include <netinet/in.h> in this file to avoid
redefinition errors.
Link: https://www.rfc-editor.org/rfc/rfc8684.html [1]
Link: https://www.mptcp.dev [2]
Today listen file descriptors created by socket unit don't get passed to
commands in Exec{Start,Stop}{Pre,Post}= socket options.
This prevents ExecXYZ= commands from accessing the created socket FDs to do
any kind of system setup which involves the socket but is not covered by
existing socket unit options.
One concrete example is to insert a socket FD into a BPF map capable of
holding socket references, such as BPF sockmap/sockhash [1] or
reuseport_sockarray [2]. Or, similarly, send the file descriptor with
SCM_RIGHTS to another process, which has access to a BPF map for storing
sockets.
To unblock this use case, pass ListenXYZ= file descriptors to ExecXYZ=
commands as listen FDs [4]. As an exception, ExecStartPre= command does not
inherit any file descriptors because it gets invoked before the listen FDs
are created.
This new behavior can potentially break existing configurations. Commands
invoked from ExecXYZ= might not expect to inherit file descriptors through
sd_listen_fds protocol.
To prevent breakage, add a new socket unit parameter,
PassFileDescriptorsToExec=, to control whether ExecXYZ= programs inherit
listen FDs.
[1] https://docs.kernel.org/bpf/map_sockmap.html
[2] https://lore.kernel.org/r/20180808075917.3009181-1-kafai@fb.com
[3] https://man.archlinux.org/man/socket.7#SO_INCOMING_CPU
[4] https://www.freedesktop.org/software/systemd/man/latest/sd_listen_fds.html
path_simplify_full()/path_simplify() are changed to allow a NULL path, for
which a NULL is returned. Generally, callers have already asserted before that
the argument is nonnull. This way path_simplify_full()/path_simplify() and
path_simplify_alloc() behave consistently.
In sd-device.c, logging in device_set_syspath() is intentionally dropped: other
branches don't log.
In mount-tool.c, logging in parse_argv() is changed to log the user-specified
value, not the simplified string. In an error message, we should show the
actual argument we got, not some transformed version.
This adds a new "PollLimit" pair of settings to .socket units, very
similar to existing "TriggerLimit" logic. The differences are:
* PollLimit focusses on the polling on the sockets, and pauses that
temporarily if a ratelimit on that is reached. TriggerLimit otoh
focusses on the triggering effect of socket units, and stops
triggering once the ratelimit is hit.
* While the trigger limit being hit is an action that causes the socket
unit to fail the polling limit being reached will just temporarily
disable polling on the socket fd, and it is resumed once the ratelimit
interval is over.
* When a socket unit operates on multiple socket fds (e,g, ListenStream=
on both some ipv6 and an ipv4 address or so). Then the PollLimit will
be specific to each fd, while the trigger limit is specific to the
whole unit.
Implementation-wise this is mostly a wrapper around sd-event's
sd_event_source_set_ratelimit(), which exposes the desired behaviour
directly.
Usecase for all of this: socket services which when overloaded with
connections should just slow down reception of it, but not fail
persistently.
==1==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 17 byte(s) in 1 object(s) allocated from:
#0 0x7fc096c7243b in strdup (/lib64/libasan.so.8+0x7243b)
#1 0x7fc095db3899 in bus_socket_set_transient_property ../src/core/dbus-socket.c:386
#2 0x7fc095db5140 in bus_socket_set_property ../src/core/dbus-socket.c:460
#3 0x7fc095dd20f1 in bus_unit_set_properties ../src/core/dbus-unit.c:2473
#4 0x7fc095d87d53 in transient_unit_from_message ../src/core/dbus-manager.c:1025
#5 0x7fc095d8872f in method_start_transient_unit ../src/core/dbus-manager.c:1112
#6 0x7fc0944ddf4f in method_callbacks_run ../src/libsystemd/sd-bus/bus-objects.c:406
#7 0x7fc0944e7854 in object_find_and_run ../src/libsystemd/sd-bus/bus-objects.c:1319
#8 0x7fc0944e8f03 in bus_process_object ../src/libsystemd/sd-bus/bus-objects.c:1439
#9 0x7fc09454ad78 in process_message ../src/libsystemd/sd-bus/sd-bus.c:3011
#10 0x7fc09454b302 in process_running ../src/libsystemd/sd-bus/sd-bus.c:3053
#11 0x7fc09454e158 in bus_process_internal ../src/libsystemd/sd-bus/sd-bus.c:3273
#12 0x7fc09454e2f2 in sd_bus_process ../src/libsystemd/sd-bus/sd-bus.c:3300
#13 0x7fc094551a59 in io_callback ../src/libsystemd/sd-bus/sd-bus.c:3642
#14 0x7fc094727830 in source_dispatch ../src/libsystemd/sd-event/sd-event.c:4187
#15 0x7fc094731009 in sd_event_dispatch ../src/libsystemd/sd-event/sd-event.c:4808
#16 0x7fc094732124 in sd_event_run ../src/libsystemd/sd-event/sd-event.c:4869
#17 0x7fc095f7af9f in manager_loop ../src/core/manager.c:3242
#18 0x41cc7c in invoke_main_loop ../src/core/main.c:1937
#19 0x4252e0 in main ../src/core/main.c:3072
#20 0x7fc092a4a50f in __libc_start_call_main (/lib64/libc.so.6+0x2750f)
SUMMARY: AddressSanitizer: 17 byte(s) leaked in 1 allocation(s).
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
In general we almost never hit those asserts in production code, so users see
them very rarely, if ever. But either way, we just need something that users
can pass to the developers.
We have quite a few of those asserts, and some have fairly nice messages, but
many are like "WTF?" or "???" or "unexpected something". The error that is
printed includes the file location, and function name. In almost all functions
there's at most one assert, so the function name alone is enough to identify
the failure for a developer. So we don't get much extra from the message, and
we might just as well drop them.
Dropping them makes our code a tiny bit smaller, and most importantly, improves
development experience by making it easy to insert such an assert in the code
without thinking how to phrase the argument.
We checked the wrong field, which was always NULL here, so we would always
reject the assignment. We would also print the wrong string in the error
message:
$ sudo systemd-run --socket-property ListenFIFO=/tmp/fifo3 cat
Failed to start transient socket unit: Invalid socket path: FIFO
This adds a way to control SO_TIMESTAMP/SO_TIMESTAMPNS socket options
for sockets PID 1 binds to.
This is useful in journald so that we get proper timestamps even for
ingress log messages that are submitted before journald is running.
We recently turned on packet info metadata from PID 1 for these sockets,
but the timestamping info was still missing. Let's correct that.
Merge members mask invalidation into
unit_add_siblings_to_cgroup_realize_queue, this way unit_realize_cgroup
needn't be called with members mask invalidation.
We have to retain the members mask invalidation in unit_load -- although
active units would have cgroups (re)realized (unit_load queues for
realization), the realization would happen with potentially stale mask.
This reworks the user validation infrastructure. There are now two
modes. In regular mode we are strict and test against a strict set of
valid chars. And in "relaxed" mode we just filter out some really
obvious, dangerous stuff. i.e. strict is whitelisting what is OK, but
"relaxed" is blacklisting what is really not OK.
The idea is that we use strict mode whenver we allocate a new user
(i.e. in sysusers.d or homed), while "relaxed" mode is when we process
users registered elsewhere, (i.e. userdb, logind, …)
The requirements on user name validity vary wildly. SSSD thinks its fine
to embedd "@" for example, while the suggested NAME_REGEX field on
Debian does not even allow uppercase chars…
This effectively liberaralizes a lot what we expect from usernames.
The code that warns about questionnable user names is now optional and
only used at places such as unit file parsing, so that it doesn't show
up on every userdb query, but only when processing configuration files
that know better.
Fixes: #15149#15090
In subsequent commits, calls to if_nametoindex() will be replaced by a wrapper
that falls back to alternative name resolution over netlink. netlink support
requires libsystemd (for sd-netlink), and we don't want to add any functions
that require netlink in basic/. So stuff that calls if_nametoindex() for user
supplied interface names, and everything that depends on that, needs to be
moved.
People do have usernames with dots, and it makes them very unhappy that systemd
doesn't like their that. It seems that there is no actual problem with allowing
dots in the username. In particular chown declares ":" as the official
separator, and internally in systemd we never rely on "." as the seperator
between user and group (nor do we call chown directly). Using dots in the name
is probably not a very good idea, but we don't need to care. Debian tools
(adduser) do not allow users with dots to be created.
This patch allows *existing* names with dots to be used in User, Group,
SupplementaryGroups, SocketUser, SocketGroup fields, both in unit files and on
the command line. DynamicUsers and sysusers still follow the strict policy.
user@.service and tmpfiles already allowed arbitrary user names, and this
remains unchanged.
Fixes#12754.
Previously we tried to be smart: when a new unit appeared and it only
added controllers to the cgroup mask we'd update the cached members mask
in all parents by ORing in the controller flags in their cached values.
Unfortunately this was quite broken, as we missed some conditions when
this cache had to be reset (for example, when a unit got unloaded),
moreover the optimization doesn't work when a controller is removed
anyway (as in that case there's no other way for the parent to iterate
though all children if any other, remaining child unit still needs it).
Hence, let's simplify the logic substantially: instead of updating the
cache on the right events (which we didn't get right), let's simply
invalidate the cache, and generate it lazily when we encounter it later.
This should actually result in better behaviour as we don't have to
calculate the new members mask for a whole subtree whever we have the
suspicion something changed, but can delay it to the point where we
actually need the members mask.
This allows us to simplify things quite a bit, which is good, since
validating this cache for correctness is hard enough.
Fixes: #9512
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
The function is similar to path_kill_slashes() but also removes
initial './', trailing '/.', and '/./' in the path.
When the second argument of path_simplify() is false, then it
behaves as the same as path_kill_slashes(). Hence, this also
replaces path_kill_slashes() with path_simplify().
Double newlines (i.e. one empty lines) are great to structure code. But
let's avoid triple newlines (i.e. two empty lines), quadruple newlines,
quintuple newlines, …, that's just spurious whitespace.
It's an easy way to drop 121 lines of code, and keeps the coding style
of our sources a bit tigther.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
Mike Yuan
Daan De Meyer
Matthieu Baerts (NGI0)
Jakub Sitnicki
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Frantisek Sumsal
Yu Watanabe
Renaud Métrich
Michal Koutný
Topi Miettinen
xginn8