This adds an IPv4 counterpart to `IPv6ProxyNDPAddress=` for adding
manual entries to the kernel's IPv4 neighbour proxy table (check via
`ip -4 neighbour show proxy dev <dev>`). systemd-networkd only exposed
`IPv4ProxyARP=` for per-interface `proxy_arp` sysctl (automatic proxy
ARP) with no way to manage manual entries from a .network file.
To avoid duplicating the IPv6 proxy NDP code path, both families are
now combined into a single new `networkd-neighbor-proxy` module. The
IPv6 behaviour is preserved: `IPv6ProxyNDPAddress=` still implies
`IPv6ProxyNDP=yes` unless `IPv6ProxyNDP=` is explicitly disabled and
entries are still dropped if the kernel has no IPv6 support.
The same rule is applied to `IPv4ProxyARPAddress=`. It implies
`IPv4ProxyARP=yes` when the sysctl is not explicitly set and has no
effect if `IPv4ProxyARP=` has been set to false.
This keeps the user model symmetric and predictable across both
families: a single per-address setting that turns on the matching
per-interface sysctl automatically, while still letting system
administrators opt out by setting the boolean explicitly to false.
Note that the IPv4 manual NTF_PROXY entries installed here would
actually function without `proxy_arp` (unlike IPv6, where `proxy_ndp`
gates the manual entries); the implication is kept for symmetry with
`IPv6ProxyNDPAddress=` and is now called out explicitly in the man
page, together with the fact that enabling `proxy_arp` also activates
interface-wide automatic proxy ARP for routed-toward addresses on
connected subnets.
Parser-time validation rejects addresses the kernel would refuse:
the ANY/null address for both families, IPv4 and IPv6 multicast
and the IPv4 limited broadcast 255.255.255.255.
Signed-off-by: Aritra Basu <aritrbas+gh@cisco.com>
File names containing backslashes cannot be checked out on Windows,
are not handled properly by build systems such as buck, and are awkward
to work with in general, so store the \x2d slice units under sanitized
file names, and rename them to the real unit name on install via a new
optional "name" key in the units list.
The fuzz-unit-file corpus sample is renamed as well; its file name is
not meaningful to the fuzzer, and dropping the backslash means it is no
longer skipped by the meson workaround for
https://github.com/mesonbuild/meson/issues/1564, so it runs as a
regression test again.
Commit 8355eb6e11 ("meson: Check if files returned by git ls-files
actually exist") checks the paths printed by git ls-files, which are
relative to the project root, with fs.exists(), which resolves them
relative to the test/fuzz subdirectory. As a result, every corpus
sample was silently skipped, and only the generated directives tests
were registered. Resolve the paths against the project source root
instead.
When the accumulated trie key exceeds the fixed-size line buffer,
linebuf_get() returns NULL. trie_fnmatch_f() passed that NULL straight
into fnmatch() as the pattern, causing a SIGSEGV on a crafted hwdb.bin
(reachable now that recursion is capped rather than overflowing the
stack first). Treat the NULL like the other corruption checks and
return -EBADMSG.
Follow-up for 73fea38cf1
Fixes https://github.com/systemd/systemd/issues/42376
Co-developed-by: Claude Opus 4.8 <noreply@anthropic.com>
A hostile but structurally valid 382-byte PE32+ "EFI application" with a
single section whose VirtualSize is ~4 GiB and SizeOfRawData is 0 drives
uki_hash() into ~4.17 M iterations of SHA-256 over 1024 bytes of zeros
— wedging the parser for >10 s. Nine more slow-units share the same
shape. A separate MSAN finding from the new fuzzer (CIFuzz, memory
sanitizer) shows pe_load_headers() reading uninitialised heap memory
when SizeOfOptionalHeader is too small to actually contain
NumberOfRvaAndSizes.
Three tightenings in src/shared/pe-binary.c:
1. In pe_load_sections, reject sections whose PointerToRawData +
SizeOfRawData exceeds the actual file size. Raw section data must
fit inside the file; this is the parser-wide invariant
pe_hash / uki_hash / pe_read_section_data rely on.
2. In uki_hash, cap the (VirtualSize - SizeOfRawData) zero-padding
hash loop at 64 MiB. Real UKIs do not pad sections with tens of
MiB of zero-equivalent data; anything above this cap is a
malformed PE.
3. In pe_load_headers, reject a PE whose SizeOfOptionalHeader is too
small to cover up to NumberOfRvaAndSizes. Without this guard the
subsequent size-mismatch check reads uninitialised optional-header
bytes, caught by MSAN under CIFuzz.
Add the 382 B canonical reproducer (plus two structural siblings) and
the MSAN reproducer to test/fuzz/fuzz-pe-binary/. Also add a libFuzzer
harness in src/fuzz/fuzz-pe-binary.c and unit tests in
src/test/test-pe-binary.c that exercise each fix branch in isolation.
The 64 MiB hash boundary test is gated behind SYSTEMD_SLOW_TESTS so it
doesn't slow down emulated-arch CI.
This is a robustness fix, not a security fix: PE binaries consumed by
bootctl / systemd-stub / pcrlock / kernel-install / systemd-measure are
already trusted and signed at the consumer side, so the worst pre-fix
behaviour is wasted CPU on a UKI install / measure / inspect call.
Closes#42344.
Reported-by: AI-assisted libFuzzer campaign
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
The file name of the reproducer is used for test name, and the test name
is messed when the file name is too long.
Also, the mentioned issues are not regressions, but long standing bugs.
Follow-up for 73fea38cf1.
Fixes a family of OOB reads in the trie walker where attacker-controlled
offsets are loaded from a (possibly hostile) hwdb.bin and added to
hwdb->map without first checking that the resulting pointer stays inside
the mapping. Crash sites:
- trie_fnmatch_f sd-hwdb.c:187 (#42340)
- trie_search_f sd-hwdb.c:233 (#42341)
- trie_children_cmp_f /bsearch sd-hwdb.c:94 (#42342)
- hwdb_add_property sd-hwdb.c:121 (#42343)
- trie_node_from_off (UBSAN) sd-hwdb.c:83
- trie_fnmatch_f stack overflow on cyclic children (CIFuzz finding)
Commit b45a897edc ("hwdb: reject out-of-bounds fnmatch prefixes")
plugged the first site only at the prefix_off-content level, but the
crash on the read of node->prefix_off itself still happens when node is
already OOB. This is the structural fix: a single hwdb_at() helper
validates that [off, off + size) lies inside the mapping, and
trie_node_from_off() / trie_string() return NULL on OOB; every caller
treats the result as nullable and surfaces -EBADMSG.
trie_fnmatch_f() additionally caps its recursion depth at 2048; without
the cap a corrupt trie whose child offsets form a cycle (or just a deep
linear chain) drives the parser into stack-overflow rather than
returning -EBADMSG (caught by CIFuzz address sanitizer on this branch).
Additions:
- A fuzz-hwdb libFuzzer harness that drives sd_hwdb_new_from_path,
sd_hwdb_get, sd_hwdb_seek, and sd_hwdb_enumerate on attacker bytes.
- Five hand-crafted unit tests in test-sd-hwdb.c (one per crash
bucket, plus the cyclic-trie recursion case) that build a malformed
in-memory hwdb.bin and assert -EBADMSG rather than SIGSEGV /
stack-overflow.
- Regression corpus files under test/fuzz/fuzz-hwdb/ pinning each
fixed bucket, including the CIFuzz stack-overflow reproducer.
Closes#42340.
Closes#42341.
Closes#42342.
Closes#42343.
Reported-by: AI-assisted libFuzzer campaign
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
dhcp_message_verify_header() only enforced a lower bound on the input
length, so dhcp_message_parse() happily accepted arbitrarily large
buffers. Such inputs could never have been received via UDP and would
later fail in dhcp_message_build() with -E2BIG once the parsed options'
combined size exceeds UDP_PAYLOAD_MAX_SIZE, which the fuzzer surfaced as
an assertion failure.
Reject inputs above UDP_PAYLOAD_MAX_SIZE up front, so the parse stage
mirrors what the wire format can actually carry.
Follow-up for 8c18bb6547
Fixes https://github.com/systemd/systemd/issues/42147
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
When SD_DHCP_OPTION_OVERLOAD indicates that the sname and/or file header
fields are overloaded with extra DHCP options, dhcp_message_parse() merges
those options into message->options but leaves the raw bytes untouched in
the header. As a result, dhcp_message_build() emits the header (including
the overloaded bytes) verbatim, and the next parse re-parses those bytes,
appending duplicate entries to the options map (each tag's iov list grows).
Subsequent builds then differ from the first, breaking the parse/build
roundtrip.
This was caught by fuzz-dhcp-client, which asserts that two consecutive
build calls produce identical output.
Zero out the overloaded fields after parsing them, since their content has
already been merged into the options map. This makes the roundtrip
idempotent and avoids re-emitting stale overloaded data in the rebuilt
header. The JSON build/parse path was already correct (it omits sname/file
from the JSON when the overload bit is set), so only the binary path needed
fixing.
Fixes https://github.com/systemd/systemd/issues/42139
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
Looking at the corpus examples, I'm not sure the fuzzer even went into
the compat parsers. None of the files have argv[0] that'd cause
invoked_as() to go into the compat paths. So add the files to provide
a quick test and possibly bias the fuzzer search into the right
direction.
Otherwise you run into errors such as:
"""
../meson.build:2899:28: ERROR: File src/test/test-loop-util.c does not exist.
"""
when deleting a file in git without staging the deletion.
Add a simple fuzzer that verifies our machinery for parsing user records
from JSON works as intended.
The initial corpus was created with the help of Claude, so we have a
bunch of valid user records with as much fields as possible for the
initial corpus.
The echo builtin provided by some shells (mksh) will interpret \x2d as
an escape sequence. This causes meson to fail:
```
test/fuzz/meson.build:93:52: ERROR: File fuzz-unit-file/dm-back-slash.swap does not exist.
```
Bug: https://bugs.gentoo.org/969789
Then, let's make syslog_parse_identifier() returns PID as pid_t, rather
than the string.
This also makes the function refuse ridiculously long identifier.
Fixes#40456.
Fixes oss-fuzz#477990732 (https://issues.oss-fuzz.com/issues/477990732).
* Do not interleave root_directory_as_fd with stdio fields
* Do not use different serialization key for different modes
pointing to same path
* Escape stdio file paths (as per
9be46b1da8)
This adds a new `Hostname=` option to the [DHCPServerStaticLease]
section in .network files, allowing an administrator to assign a
specific hostname to a client receiving a static lease.
We automatically select the correct DHCP option to use based on the
format of the provided string:
- Single DNS labels are sent as Option 12.
- Names with multiple DNS labels are sent as Option 81 in wire format.
Fixes: #39634
This allows a service to reuse the user namespace created for an
existing service, similarly to NetworkNamespacePath=. The configuration
is the initial user namespace (e.g. ID mapping) is preserved.
Those were added before 0.61 which is our minimum version.
Dots were dropped from the end of some messages. Most messages did not have the
trailing dot.
0.63 added support for multi-line f-strings. We can't use those yet.
We went back and forth between 'prog.sh', files('prog.sh'), and
find_program('prog.sh'). We want to use files() or find_program() so that we
get a good error message if the file is missing. Behaviour of meson changed
over time, and in the past not all forms could be used in all places. For
example 0f4c4f3824 added find_program() in many
places to avoid repeated messages. But it seems that all recent meson versions
work fine with files().
find_program prints silly messages:
Program tools/make-man-index.py found: YES
(/home/zbyszek/src/systemd/tools/make-man-index.py)
Program tools/meson-render-jinja2.py found: YES
(/home/zbyszek/src/systemd/tools/meson-render-jinja2.py)
...
We know that those files will be found, they are part of the git checkout.
With files() this is gone and the meson output is easier to read.
All those files are standalone programs that can be executed directly.
Some .py files were marked executable, others weren't, probably accidentally.
Mark them all as executable in preparation for subsequent changes.
[1] says:
> Since 0.60.0 the name argument is optional and defaults to the basename of
> the first output
We specify >= 0.62 as the supported version, so drop the duplicate name in all cases
where it is the same as outputs[0], i.e. almost all cases.
[1] https://mesonbuild.com/Reference-manual_functions.html#custom_target
Currently, when fuzzers are enabled, we run meson from within meson
to build the fuzzer executables with sanitizers. The idea is that
we can build the fuzzers with different kinds of sanitizers
independently from the main build.
The issue with this setup is that we don't actually make use of it.
We only build the fuzzers with one set of sanitizers (address,undefined)
so we're adding a bunch of extra complexity without any benefit as we
can just setup the top level meson build with these sanitizers and get
the same result.
The other issue with this setup is that we don't pass on all the options
passed to the top level meson build to the nested meson build. The only things
we pass on are extra compiler arguments and the value of the auto_features
option, but none of the individual feature options if overridden are passed on,
which can lead to very hard to debug issues as an option enabled in the top
level build is not enabled in the nested build.
Since we're not getting anything useful out of this setup, let's simplify
and get rid of the nested meson build. Instead, sanitizers should be enabled
for the top level meson.build. This currently didn't work as we were overriding
the sanitizers passed to the meson build with the fuzzer sanitizer, so we
fix that as well by making sure we combine the fuzzer sanitizer with the ones
passed in by the user.
We also drop support for looking up libFuzzer as a separate library as
it has been shipped builtin in clang since clang 6.0, so we can assume
that -fsanitize=fuzzer is available.
To make sure we still run the fuzzing tests, we enable the fuzz-tests option
by default now to make sure they still always run (without instrumentation unless
one of llvm-fuzz or oss-fuzz is enabled).
The structure of DNR options is considerably more complicated than most
DHCP options, and as a result the fuzzer has poor coverage of these code
paths.
This adds some DNR packets to the fuzzing corpus, not with the intent of
capturing some specific edge case, but with the intent to rapidly
improve the fuzzers' coverage of these codepaths by giving it a valid
example to begin with.
Also include an ndisc router advert with a few Encrypted DNS options,
for the same purpose.
This will allow units (scopes/slices/services) to override the default
systemd-oomd setting DefaultMemoryPressureDurationSec=.
The semantics of ManagedOOMMemoryPressureDurationSec= are:
- If >= 1 second, overrides DefaultMemoryPressureDurationSec= from oomd.conf
- If is empty, uses DefaultMemoryPressureDurationSec= from oomd.conf
- Ignored if ManagedOOMMemoryPressure= is not "kill"
- Disallowed if < 1 second
Note the corresponding dbus property is DefaultMemoryPressureDurationUSec
which is in microseconds. This is consistent with other time-based
dbus properties.
The family will be checked later in
address_section_verify() -> address_section_adjust_broadcast(),
hence it is not necessary to set here.
Follow-up for 5d15c7b19c.
Fixes oss-fuzz#372994449.
Fixes#34748.
By default, in instances where timers are running on a realtime schedule,
if a service takes longer to run than the interval of a timer, the
service will immediately start again when the previous invocation finishes.
This is caused by the fact that the next elapse is calculated based on
the last trigger time, which, combined with the fact that the interval
is shorter than the runtime of the service, causes that elapse to be in
the past, which in turn means the timer will trigger as soon as the
service finishes running.
This behavior can be changed by enabling the new DeferReactivation setting,
which will cause the next calendar elapse to be calculated based on when
the trigger unit enters inactivity, rather than the last trigger time.
Thus, if a timer is on an realtime interval, the trigger will always
adhere to that specified interval.
E.g. if you have a timer that runs on a minutely interval, the setting
guarantees that triggers will happen at *:*:00 times, whereas by default
this may skew depending on how long the service runs.
Co-authored-by: Matteo Croce <teknoraver@meta.com>
This fixes the following assertion:
===
SYSTEMD_LOG_LEVEL=debug systemctl --user -H foo --boot-loader-entry=help
Assertion 'transport != BUS_TRANSPORT_REMOTE || runtime_scope == RUNTIME_SCOPE_SYSTEM' failed at src/shared/bus-util.c:284, function bus_connect_transport(). Ignoring.
Failed to connect to bus: Operation not supported
===
Fixes a bug introduced by 97af80c5a7.
Fixes#33661.
Fixes oss-fuzz#70153.
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]
