Our journal code is generally supposed to be written in a fashion that
the underlying file can be deallocated any time, i.e. our mmap of it
suddenly becomes all zeroes. The idea is that we catch that when parsing
everything. For that to work safely we need to make sure that when doing
arithmetics or comparisons on values read from the map we don't run into
TTOCTTOU issues when determining validity. Hence we need to copy out the
values before use and operate on the copies. This requires some special
care since the C compiler could suppress our copies as optimization.
Hence use the new READ_NOW() macro to force a copy by using memcpy(),
and use it whenever we start doing an arithmetic operation on it, or
validity checking of multiple steps.
Fixes: #14943
https://bugzilla.redhat.com/show_bug.cgi?id=1715699
> /dev/mapper/live-rw 6.4G 5.7G 648M 91% /
> systemd-journald[905]: Fixed min_use=1.0M max_use=648.7M max_size=81.0M min_size=512.0K keep_free=973.1M n_max_files=100
When journald is started, we pick keep_free as 15% of the disk size. When the
fs is almost filled, we will only keep one journal file around and rotate very
often (because min_size is very small).
Let's set min use to something reasonable, so that we get more useful logs that
will cover at least the full boot.
Some cases considered in the PR:
> /dev/mapper/live-rw 6.4G 5.7G 648M 91% /
keep_free→MIN(327,100)→100 MB.
min_use→16MB.
effective range: 16 MB – 548 MB
> /dev/mapper/fedora_krowka-root 78G 69G 5.7G 93% /
keep_free → MIN(4GB, 100MB)→100MB
min_use→16MB
effective range: 16 MB – 5.6 GB
(but then there's the max_use limit, which cuts the range down)
> 4TB, 4GB free
keep_free → MIN(209715, 100) → 100 MB
min_use→16MB
effective range: 16 MB – 4.9 GB
(also effectively limited by max_use)
Also replace unneeded width suffixes with spaces, I think this is more
readable, and drop DEFAULT_ prefixes in cases where this setting is
simply a bound, and cannot be overridden by user config, hence is not
a default.
systemd-journal-remote always wrote the boot-id of the device it was running on
to the header of its journal files. When the source had a different boot-id
(because it was generated on a different boot, or a different device), the
boot-ids in the file were inconsistent. The _BOOT_ID field was that of the
source, but the journal file header and each entry object header were that of
the device systemd-journal-remote ran on. This breaks journalctl --list-boots
on any of these files.
Set the boot-id in the header to be that of the source. This also fixes the
entry object headers.
The thread launched in journal_file_set_offline() accesses a memory
mapped file, so it needs to handle SIGBUS. Leave SIGBUS unblocked on the
offlining thread so that it uses the same handler as the main thread.
The result of triggering SIGBUS in a thread where it's blocked is
undefined in Linux. The tested implementations were observed to cause
the default handler to run, taking down the whole journald process.
We can leave SIGBUS unblocked in multiple threads since it's handler is
thread-safe. If SIGBUS is sent to the journald process asynchronously
(i.e. with kill, sigqueue, or raise), either thread handling it will
result in the same behavior: it will install the default handler and
reraise the signal, killing the process.
Fixes: #12042
Continuation of a3ebe5eb620e49f0d24082876cafc7579261e64f:
in other places we sometimes use assert_se(), and sometimes normal error
handling. sigfillset and sigaddset can only fail if mask is NULL (which cannot
happen if we are passing in a reference), or if the signal number is invalid
(which really shouldn't happen when we are using a constant like SIGCHLD. If
SIGCHLD is invalid, we have a bigger problem). So let's simplify things and
always use assert_se() in those cases.
In sigset_add_many() we could conceivably pass an invalid signal, so let's keep
normal error handling here. The caller can do assert_se() around the
sigprocmask_many() call if appropriate.
'>= 0' is used for consistency with the rest of the codebase.
Ideally, coccinelle would strip unnecessary braces too. But I do not see any
option in coccinelle for this, so instead, I edited the patch text using
search&replace to remove the braces. Unfortunately this is not fully automatic,
in particular it didn't deal well with if-else-if-else blocks and ifdefs, so
there is an increased likelikehood be some bugs in such spots.
I also removed part of the patch that coccinelle generated for udev, where we
returns -1 for failure. This should be fixed independently.
Let's split out the part that actually renames the file in case we can't
open it into a new function journal_file_dispose().
This way we can reuse the function in other cases where we want to open
a file but can't.
Let's split the function in three: the part where we archive the old
file into journal_file_archive(), and the part where we initiate the
deferred closing into journal_file_initiate_close().
journal_file_rotate() then simply becomes a wrapper around these two
calls, and the opening of the new journal file.
This useful so that we can archive journal files without having to open
new ones, i.e. to do only the archival part of the rotation, without the
rotation part.
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 journal verification functions would reject such an entry. It would probably
still display fine (because we prefer _SOURCE_REALTIME_TIMESTAMP= if present), but
it seems wrong to create an entry that would not pass verification.
The code to open journal files seems like the wrong place to enforce this. We
already check during boot and refuse to boot if machine-id is missing, no need
to enforce this here. In particular, it seems better to write logs from
journald even if they are not completely functional rather than refuse to
operate at all, and systemd-journal-remote also writes journal files and may
even be run on a system without systemd at all.
The docker image that oss-fuzz uses has an empty /etc/machine-id. Obviously
this is an error in the docker, but docker is fact of life, and it seems better
for systemd-journal-remote to work in such an incomplete environment.
In journal_file_set_online() the offline thread doesn't need to be
joined if it's been canceled before actually reaching the phase of
writing the offline state.
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.
It might happen that we try to bisect through a chain of offset arrays in the
journal whose last element was just allocated but no item yet written
to. In that case that array will be all NUL, but it might still end up
in our array chain cache. If it does, we cannot use it for bisection,
since for bisection we need to know the value of the first entry in that
array, but if it's uninitialized it does not have a first value. Hence,
as a simple fix, in this unlikely case, simply ignore the chain cache.
This is supposed to fix the issue pointed out in #8432, but in a more
permissive way, as this case isn't strictly a badly formatted journal
but actually a valid state (though one within a very short time window),
and we should make the best of it, and handle it gracefully.
Background: in each journal file entries are linked up in large arrays
of offsets. In each array the entries are strictly ordered by the
offsets of the entries, which permits search by bisection. These arrays
are allocated with a fixed size and then filled up as entries are added
to the journal file. If an array is fully filled up, a new array
(double in size as the old one) is appended to the journal file, and
linked up. This means, the journal file will contain a series of chained
up arrays, each time doubling in size, and strictly ordered. When
looking for an entry we maintain a "chain cache", which allows us to
bypass traversing the chain in full if we look for entries close to each
other in a short time. With the fix above we make sure we don't
erroneously use a chain cache item that doesn't carry enough information
for this bisection to work.
Original issue identified (with patch) by @Kxuan.
Replaces: #8432
Previously the compression threshold was hardcoded to 512, which meant that
smaller values wouldn't be compressed. This left some storage savings on the
table, so instead, we make that number tunable.
