We'd first parse all or most of the message, and only then consider if it
is not too large. Also, when encountering a single field over the limit,
we'd still process the preceding part of the message. Let's be stricter,
and check size limits early, and let's refuse the whole message if it fails
any of the size limits.
We allocate a iovec entry for each field, so with many short entries,
our memory usage and processing time can be large, even with a relatively
small message size. Let's refuse overly long entries.
CVE-2018-16865
https://bugzilla.redhat.com/show_bug.cgi?id=1653861
What from I can see, the problem is not from an alloca, despite what the CVE
description says, but from the attack multiplication that comes from creating
many very small iovecs: (void* + size_t) for each three bytes of input message.
If creation of the message failed, we'd write a bogus entry:
systemd-coredump[1400]: Cannot store coredump of 416 (systemd-journal): No space left on device
systemd-coredump[1400]: MESSAGE=Process 416 (systemd-journal) of user 0 dumped core.
systemd-coredump[1400]: Coredump diverted to
This affects systemd-journald and systemd-coredump.
Example entry:
$ journalctl -o export -n1 'MESSAGE=Something logged'
__CURSOR=s=976542d120c649f494471be317829ef9;i=34e;b=4871e4c474574ce4a462dfe3f1c37f06;m=c7d0c37dd2;t=57c4ac58f3b98;x=67598e942bd23dc0
__REALTIME_TIMESTAMP=1544035467475864
__MONOTONIC_TIMESTAMP=858200964562
_BOOT_ID=4871e4c474574ce4a462dfe3f1c37f06
PRIORITY=6
_UID=1000
_GID=1000
_CAP_EFFECTIVE=0
_SELINUX_CONTEXT=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
_AUDIT_SESSION=1
_AUDIT_LOGINUID=1000
_SYSTEMD_OWNER_UID=1000
_SYSTEMD_UNIT=user@1000.service
_SYSTEMD_SLICE=user-1000.slice
_SYSTEMD_USER_SLICE=-.slice
_SYSTEMD_INVOCATION_ID=1c4a469986d448719cb0f9141a10810e
_MACHINE_ID=08a5690a2eed47cf92ac0a5d2e3cf6b0
_HOSTNAME=krowka
_TRANSPORT=syslog
SYSLOG_FACILITY=17
SYSLOG_IDENTIFIER=syslog-caller
MESSAGE=Something logged
_COMM=poc
_EXE=/home/zbyszek/src/systemd-work3/poc
_SYSTEMD_CGROUP=/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service
_SYSTEMD_USER_UNIT=gnome-terminal-server.service
SYSLOG_PID=4108
SYSLOG_TIMESTAMP=Dec 5 19:44:27
_PID=4108
_CMDLINE=./poc AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA>
_SOURCE_REALTIME_TIMESTAMP=1544035467475848
$ journalctl -o export -n1 'MESSAGE=Something logged' --output-fields=_CMDLINE|wc
6 2053 2097410
2MB might be hard for some clients to use meaningfully, but OTOH, it is
important to log the full commandline sometimes. For example, when the program
is crashing, the exact argument list is useful.
This fixes a crash where we would read the commandline, whose length is under
control of the sending program, and then crash when trying to create a stack
allocation for it.
CVE-2018-16864
https://bugzilla.redhat.com/show_bug.cgi?id=1653855
The message actually doesn't get written to disk, because
journal_file_append_entry() returns -E2BIG.
systemd-coredump[9982]: MESSAGE=Process 771 (systemd-journal) of user 0 dumped core.
systemd-coredump[9982]: Coredump diverted to /var/lib/systemd/coredump/core...
log_dispatch() calls log_dispatch_internal() which calls write_to_journal()
which appends MESSAGE= on its own.
- Don't redefine helpers on every call
- Prefix helper names with main function name
- Adjust some helper names for consistency and convention adherance
When running PROGRAM="...", we would log
systemd-udevd[447]: Failed to wait spawned command '...': Input/output error
no matter why the program actually failed, at error level.
The code wouldn't distinguish between an internal failure and a failure in the
program being called and run sd_event_exit(..., -EIO) on any kind of error. EIO
is rather misleading here, becuase it suggests a serious error.
on_spawn_sigchld is updated to set the return code to distinguish failure to
spawn, including the program being killed by a signal (a negative return value),
and the program failing (positive return value).
The logging levels are adjusted, so that for PROGRAM= calls, which are
essentially "if" statements, we only log at debug level (unless we get a
timeout or segfault or another unexpected error).
There's very little lost if the variable is set for a socket that isn't
connectible, but a lot lost (races, ...) if it's not set but the socket exists.
Also, drop the FIXME note, since we don't plan to revert this revert any time
soon.
Based on the journalctl documentation of this option added in 23ad99b519
(#10527), but with the first reference to “fields” replaced by “journal
messages”, since I think it’s less common to show other fields with
`systemctl status` (though it’s possible with the `-o` option).
This reverts commit 0c2e93b863.
This should not be necessary anymore after previous commit.
I don't quite remember what sequence of steps was failing, but right now
"meson build -Dslow-tests=true && ninja -C build fuzzers" work fine.
It seems quite useful to provide this additional information in public exported
functions.
This is a c99 feature, not supported in C++. Without the check in _sd-common.h:
FAILED: test-bus-vtable-cc@exe/src_libsystemd_sd-bus_test-bus-vtable-cc.cc.o
...
In file included from ../src/libsystemd/sd-bus/test-bus-vtable-cc.cc:9:
In file included from ../src/systemd/sd-bus-vtable.h:26:
In file included from ../src/systemd/sd-bus.h:26:
../src/systemd/sd-id128.h:38:47: error: static array size is a C99 feature, not permitted in C++
char *sd_id128_to_string(sd_id128_t id, char s[static SD_ID128_STRING_MAX]);
^
In .c files, I opted to use the define for consistency, even though we don't support
compilation with a C++ compiler, so the unconditional keyword would work too.
