Domain deallocation records are emitted asynchronously from kworker
threads (via free_ruleset_work()). Stale deallocation records from a
previous test can arrive during the current test's deallocation read
loop and be picked up by audit_match_record() instead of the expected
record, causing a domain ID mismatch. The audit.layers test (which
creates 16 nested domains) is particularly vulnerable because it reads
16 deallocation records in sequence, providing a large window for stale
records to interleave.
The same issue affects audit_flags.signal, where deallocation records
from a previous test (audit.layers) can leak into the next test and be
picked up by audit_match_record() instead of the expected record.
Fix this by continuing to read records when the type matches but the
content pattern does not. Stale records are silently consumed, and the
loop only stops when both type and pattern match (or the socket times
out with -EAGAIN).
Additionally, extend matches_log_domain_deallocated() with an
expected_domain_id parameter. When set, the regex pattern includes the
specific domain ID as a literal hex value, so that deallocation records
for a different domain do not match the pattern at all. This handles
the case where the stale record has the same denial count as the
expected one (e.g. both have denials=1), which the type+pattern loop
alone cannot distinguish. Callers that already know the expected domain
ID (from a prior denial or allocation record) now pass it to filter
precisely.
When expected_domain_id is set, matches_log_domain_deallocated() also
temporarily increases the socket timeout to audit_tv_dom_drop (1 second)
to wait for the asynchronous kworker deallocation, and restores
audit_tv_default afterward. This removes the need for callers to manage
the timeout switch manually.
Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b2297 ("selftests/landlock: Add tests for audit flags and domain IDs")
Link: https://lore.kernel.org/r/20260402192608.1458252-5-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Non-audit Landlock tests generate audit records as side effects when
audit_enabled is non-zero (e.g. from boot configuration). These records
accumulate in the kernel audit backlog while no audit daemon socket is
open. When the next test opens a new netlink socket and registers as
the audit daemon, the stale backlog is delivered, causing baseline
record count checks to fail spuriously.
Fix this by draining all pending records in audit_init() right after
setting the receive timeout. The 1-usec SO_RCVTIMEO causes audit_recv()
to return -EAGAIN once the backlog is empty, naturally terminating the
drain loop.
Domain deallocation records are emitted asynchronously from a work
queue, so they may still arrive after the drain. Remove records.domain
== 0 checks that are not preceded by audit_match_record() calls, which
would otherwise consume stale records before the count. Document this
constraint above audit_count_records().
Increasing the drain timeout to catch in-flight deallocation records was
considered but rejected: a longer timeout adds latency to every
audit_init() call even when no stale record is pending, and any fixed
timeout is still not guaranteed to catch all records under load.
Removing the unprotected checks is simpler and avoids the spurious
failures.
Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b2297 ("selftests/landlock: Add tests for audit flags and domain IDs")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260402192608.1458252-4-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
audit_init() opens a netlink socket and configures it, but leaks the
file descriptor if audit_set_status() or setsockopt() fails. Fix this
by jumping to an error path that closes the socket before returning.
Apply the same fix to audit_init_with_exe_filter(), which leaks the file
descriptor from audit_init() if audit_init_filter_exe() or
audit_filter_exe() fails, and to audit_cleanup(), which leaks it if
audit_init_filter_exe() fails in FIXTURE_TEARDOWN_PARENT().
Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b2297 ("selftests/landlock: Add tests for audit flags and domain IDs")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260402192608.1458252-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
snprintf() returns the number of characters that would have been
written, excluding the terminating NUL byte. When the output is
truncated, this return value equals or exceeds the buffer size. Fix
matches_log_domain_allocated() and matches_log_domain_deallocated() to
detect truncation with ">=" instead of ">".
Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Fixes: 6a500b2297 ("selftests/landlock: Add tests for audit flags and domain IDs")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260402192608.1458252-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Add audit.thread tests to check that the PID tied to a domain is not a
thread ID but the thread group ID. These new tests would not pass
without the previous TGID fix.
Extend matches_log_domain_allocated() to check against the PID that
created the domain.
Test coverage for security/landlock is 93.6% of 1524 lines according to
gcc/gcov-14.
Cc: Christian Brauner <brauner@kernel.org>
Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20250410171725.1265860-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Add audit_test.c to check with and without LANDLOCK_RESTRICT_SELF_*
flags against the two Landlock audit record types:
AUDIT_LANDLOCK_ACCESS and AUDIT_LANDLOCK_DOMAIN.
Check consistency of domain IDs per layer in AUDIT_LANDLOCK_ACCESS and
AUDIT_LANDLOCK_DOMAIN messages: denied access, domain allocation, and
domain deallocation.
These tests use signal scoping to make it simple. They are not in the
scoped_signal_test.c file but in the new dedicated audit_test.c file.
Tests are run with audit filters to ensure the audit records come from
the test program. Moreover, because there can only be one audit
process, tests would failed if run in parallel. Because of audit
limitations, tests can only be run in the initial namespace.
The audit test helpers were inspired by libaudit and
tools/testing/selftests/net/netfilter/audit_logread.c
Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Phil Sutter <phil@nwl.cc>
Link: https://lore.kernel.org/r/20250320190717.2287696-23-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
