Whenever we're going to close all file descriptors, we tend to close
the log and set it into open when needed mode. When this is done with
the logging target set to LOG_TARGET_AUTO, we run into issues because
for every logging call, we'll check if stderr is connected to the
journal to determine where to send the logging message. This check
obviously stops working when we close stderr, so we settle the log
target before we do that so that we keep using the same logging
target even after stderr is closed.
IN C23, thread_local is a reserved keyword and we shall therefore
do nothing to redefine it. glibc has it defined for older standard
version with the right conditions.
v2 by Yu Watanabe:
Move the definition to missing_threads.h like the way we define e.g.
missing syscalls or missing definitions, and include it by the users.
Co-authored-by: Yu Watanabe <watanabe.yu+github@gmail.com>
This commit adds support for attaching extra metadata to log
messages written to the journal via log.h. We keep track of a
thread local log context in log.c onto which we can push extra
metadata fields that should be logged. Once a field is no longer
relevant, it can be popped again from the log context.
On top of this, we then add macros to allow pushing extra fields
onto the log context.
LOG_CONTEXT_PUSH() will push the provided field onto the log context
and pop the last field from the log context when the current block
ends. LOG_CONTEXT_PUSH_STRV() will do the same but for all fields in
the given strv.
Using the macros is as simple as putting them anywhere inside a block
to add a field to all following log messages logged from inside that
block.
void myfunction(...) {
...
LOG_CONTEXT_PUSH("MYMETADATA=abc");
// Every journal message logged will now have the MYMETADATA=abc
// field included.
}
For convenience, there's also LOG_CONTEXT_PUSHF() to allow constructing
the field to be logged using printf() syntax.
log_context_new()/log_context_free() can be used to attach a log context
to an async operation by storing it in the associated userdata struct.
-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.
I wanted to move saved_arg[cv] to process-util.c+h, but this causes problems:
process-util.h includes format-util.h which includes net/if.h, which conflicts
with linux/if.h. So we can't include process-util.h in some files.
But process-util.c is very long anyway, so it seems nice to create a new file.
rename_process(), invoked_as(), invoked_by_systemd(), and argv_looks_like_help()
which lived in process-util.c refer to saved_argc and saved_argv, so it seems
reasonable to move them to the new file too.
util.c is now empty, so it is removed. util.h remains.
In general, log_syntax_internal() must keep errno unchanged. But the
call to log_syntax_callback() was added outside of the block protected
by PROTECT_ERRNO.
log_parse_environment() uses should_parse_proc_cmdline() to determine whether
it should parse settings from the kernel command line. But the checks that
should_parse_proc_cmdline() apply to the whole process, and we could get a positive
answer also when log_parse_environment() was called from one of the nss modules.
In case of nss-modules, we don't want to look at the kernel command line.
log_parse_environment_variables() that only looks at the environment variables
is split out and used in the nss modules.
Fixes#22020.
Previously, we discarded any kmsg messages coming from journald
itself to avoid infinite loops where potentially the processing
of a kmsg message causes journald to log one or more messages to
kmsg which then get read again by the kmsg handler, ...
However, if we completely disable logging whenever we're processing
a kmsg message coming from journald itself, we also prevent any
infinite loops as we can be sure that journald won't accidentally
generate logging messages while processing a kmsg log message.
This change allows us to store all journald logs generated during
the processing of log messages from other services in the system
journal. Previously these could only be found in kmsg which has
low retention, can't be queried using journalctl and whose logs
don't survive reboots.
Let's define two helpers strdupa_safe() + strndupa_safe() which do the
same as their non-safe counterparts, except that they abort if called
with allocations larger than ALLOCA_MAX.
This should ensure that all our alloca() based allocations are subject
to this limit.
afaics glibc offers three alloca() based APIs: alloca() itself,
strndupa() + strdupa(). With this we have now replacements for all of
them, that take the limit into account.
The commit introduces a callback invoked from log_syntax_internal.
Use it from systemd-analyze to gather a list of units that contain
syntax warnings. A new command line option is added to make use of this.
The new option --recursive-errors takes in three possible modes:
1. yes - which is the default. systemd-analyze exits with an error when syntax warnings arise during verification of the
specified units or any of their dependencies.
3. no - systemd-analyze exits with an error when syntax warnings arise during verification of only the selected unit.
Analyzing and loading any dependencies will be skipped.
4. one - systemd-analyze exits with an error when syntax warnings arise during verification
of only the selected units and their direct dependencies.
Below are two service unit files that I created for the purposes of testing:
1. First, we run the commands on a unit that does not have dependencies but has a non-existing key-value setting (i.e. foo = bar).
> cat <<EOF>testcase.service
[Unit]
foo = bar
[Service]
ExecStart = echo hello
EOF
OUTPUT:
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify testcase.service
/home/maanya-goenka/systemd/testcase.service:2: Unknown key name 'foo' in section 'Unit', ignoring.
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=yes testcase.service
/home/maanya-goenka/systemd/testcase.service:2: Unknown key name 'foo' in section 'Unit', ignoring.
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=no testcase.service
/home/maanya-goenka/systemd/testcase.service:2: Unknown key name 'foo' in section 'Unit', ignoring.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=one testcase.service
/home/maanya-goenka/systemd/testcase.service:2: Unknown key name 'foo' in section 'Unit', ignoring.
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
2. Next, we run the commands on a unit that is syntactically valid but has a non-existing dependency (i.e. foo2.service)
> cat <<EOF>foobar.service
[Unit]
Requires = foo2.service
[Service]
ExecStart = echo hello
EOF
OUTPUT:
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify foobar.service
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
foobar.service: Failed to create foobar.service/start: Unit foo2.service not found.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=yes foobar.service
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
foobar.service: Failed to create foobar.service/start: Unit foo2.service not found.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=no foobar.service
maanya-goenka@debian:~/systemd (log-error)$ echo $?
0
maanya-goenka@debian:~/systemd (log-error)$ sudo build/systemd-analyze verify --recursive-errors=one foobar.service
/usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
/usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
/usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your unit file, and consider removing the setting altogether.
foobar.service: Failed to create foobar.service/start: Unit foo2.service not found.
maanya-goenka@debian:~/systemd (log-error)$ echo $?
1
We had 'msghdr' and 'mh' in various places. Now 'const struct msghdr msghdr' is
used consistently. With structured init the variable is only used in the call
to sendmsg(), so let's make it a bit more descriptive.
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 would try to return a value that could be nonzero only if the kernel
reported writing more bytes than we gave to it, hopefully a rare occurence.
Instead, assert that this doesn't happen.
Instead, return true if we got to the end of the iovec array. The caller
can use this information to know that the whole iovec array was written.
This allows one loop to be dropped in write_to_syslog().
Also drop _unlikely_: this function is called with very short arrays, and
it *is* likely that we trigger this condition. Let's just let the compiler
generate normal code without giving it a potentially false hint.
Commit 0b1f3c768c has introduced log_open()
calls after exec fails post-fork. However, the log_open() call itself could
change the value of errno, which, for me, manifested in:
$ coredumpctl gdb
...
Failed to invoke gdb: Success
Fix this by using PROTECT_ERRNO in log_open().
CLI tools may be used in a script. E.g., a script for monitoring a
service may use `systemctl`. Previously, if the kernel command line has
e.g. systemd.log-level=debug, then systemctl in the script produces
debugging logs when the script is invoked by a .service unit, but does
not when the script is running in a terminal. Then,
https://github.com/systemd/systemd/pull/18281#discussion_r561697482,
> I expect users to be (negatively) surprised.
In the previous commit, $SYSTEMD_EXEC_PID= is introduced. Then, we can
now detect whether a command is directly invoked by systemd or through
a script. Let's skip reading the kernel command line when a command is
invoked through a script.
This effectively reverts 41d1f469cf.
Before this, e.g., `networkctl reload` invoked by `systemctl reload systemd-networkd.service`
does not produce debugging logs even if systemd.log-level=debug is set. This fixes
the issue.
THis doesn't change the condition's logic at all, but is an attempt to
make things a bit more readable: instead of checking log_target !=
LOG_TARGET_AUTO let's actually list the targets where we want to
consider journal/syslog/kmsg, to make things a bit less confusing. After
all the message here is not to avoid them if LOG_TARGET_AUTO is set, but
to definitely do them in the other cases.
It always was the intention to expose this as trusted field _TID=, i.e.
automatically determine it from journald via some SCM_xyz field or so,
but this is never happened, and it's unlikely this will be added anytime
soon to the kernel either, hence let's just generate this sender side,
even if it means it's untrusted.
This was needed before commit 16e4fd87c5 added a
mode that opens the log fds for every single log message. This mode is used in
execute.c since then making the explicit call to log_open unnecessary.
This basically reverts ea89a119cd.
Presently, CLI utilities such as systemctl will check whether they have a tty
attached or not to decide whether to parse /proc/cmdline or EFI variable
SystemdOptions looking for systemd.log_* entries.
But this check will be misleading if these tools are being launched by a
daemon, such as a monitoring daemon or automation service that runs in
background.
Make log handling of CLI tools uniform by never checking /proc/cmdline or EFI
variables to determine the logging level.
Furthermore, introduce a new log_setup_cli() shortcut to set up common options
used by most command-line utilities.
Daan De Meyer
Luca Boccassi
Cristian RodríguezandYu Watanabe
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Maanya Goenka
Sergey Bugaev
rnhmjoj
Franck Bui
Filipe Brandenburger
Dan Streetman