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Scope and ptrace denials follow a different code path (a domain
hierarchy check) than access-right denials, so they need dedicated
tracepoints with type-specific TP_PROTO arguments. Complete the denial
coverage with:
- landlock_deny_ptrace: ptrace access denied by a domain hierarchy
mismatch.
- landlock_deny_scope_signal: signal delivery denied by
LANDLOCK_SCOPE_SIGNAL.
- landlock_deny_scope_abstract_unix_socket: abstract unix socket access
denied by LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET.
TP_PROTO passes the raw kernel object (struct task_struct or struct
sock) for eBPF BTF access; the comm and sun_path string fields use
__print_untrusted_str() because they hold untrusted input. Unlike the
deny_access events, these omit the blockers field: each maps to exactly
one denial type named by the event, so the bitmask would always be zero.
Like the deny_access events they carry same_exec and logged.
Audit logs the task-targeted denials with generic field names (opid,
ocomm), but a strongly typed trace event can use role-prefixed names
(tracee_pid/tracee_comm, target_pid/target_comm) that match the mainline
task-name convention (sched_process_fork's parent_comm/child_comm) and
say whose name each field holds; a bare comm= would collide across
events. The abstract-unix-socket event reports peer_pid instead, a
tracepoint-only field with no audit counterpart.
A scope or ptrace verdict compares the subject domain against the other
party's domain, so each event also reports that other party's Landlock
domain (tracee_domain=, target_domain=, or peer_domain=); the subject
domain= alone does not let a consumer redo domain_is_scoped() or
domain_ptrace(). It is reported as a scalar ID rather than a domain
pointer: a domain object is immutable, but the other task can replace
its credential and free the domain that credential referenced, so a
stored foreign pointer could dangle before the event is consumed. The
scalar ID also honors the tracepoint no-nullable-pointer rule, since the
other party is frequently unsandboxed. Passing the foreign domain
hierarchy object so an eBPF consumer could walk the other party's
ancestry live would lengthen the RCU section on the shared denial path
and needs a deferred refcount put, so it is left as a future
enhancement. The relational domain-ID field (tracee_domain,
target_domain, or peer_domain) is trace-only and is not added to audit
records, so audit's denial format is unchanged by this series.
Cc: Günther Noack <gnoack@google.com>
Cc: Justin Suess <utilityemal77@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://patch.msgid.link/20260811094338.288094-14-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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Add per-type tracepoints emitted from landlock_log_denial() when an
access is denied: landlock_deny_access_fs for filesystem denials and
landlock_deny_access_net for network denials. They use the "deny_"
prefix (rather than "check_") to mark that they fire only on a denial,
and they complement the check_rule events by making the
denial-by-absence case explicit (when no rule matches, no check_rule
event fires).
Unlike the audit records, these events fire regardless of the audit
configuration and the domain's log flags: the user's "disable logging"
intent applies to audit records, not to kernel tracing. The logged
field records whether the domain's log policy would submit the denial to
audit; it is the decision computed once by landlock_log_denial() and
passed to both the audit and the tracing emitter, so a stateless ftrace
filter can select the audit-visible denials with logged==1.
TP_PROTO passes the denying hierarchy node, not the task's current
domain, so domain_id reports the specific node that blocked the access,
matching audit record semantics. (check_rule instead passes the current
domain, which it needs to size its per-layer array.) same_exec is also
passed explicitly because it is computed from the credential bitmask and
is not derivable from the hierarchy pointer alone. The denial field is
named blockers to match the audit record field.
The filesystem path comes from the request's audit data. Its type
selects which union member holds the object, exactly as
dump_common_audit_data() selects it (a path, a file's path, an ioctl
op's path, or a bare dentry); reading the wrong member would dereference
garbage, so every reachable type has an explicit case and an unexpected
one is flagged with WARN_ONCE() instead of misread. Path-backed types
resolve via d_absolute_path() (as landlock_add_rule_fs does) and the
bare-dentry case via dentry_path_raw().
The inode number is read defensively. A filesystem denial can carry a
negative dentry (no backing inode), for example a denied creation, so
the event mirrors the guard in dump_common_audit_data() and reports
inode 0 rather than dereferencing a NULL inode. The sibling fs
tracepoints do not need the guard: a dentry that matches a rule during
an access check, or one opened to add a rule, always has a backing
inode. Landlock tracepoints are reachable by unprivileged sandboxees,
so a denial on a negative dentry with the event enabled must not fault
the kernel.
Cc: Günther Noack <gnoack@google.com>
Cc: Justin Suess <utilityemal77@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://patch.msgid.link/20260811094338.288094-13-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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Add a landlock_create_domain tracepoint emitted from
landlock_restrict_self() after the new domain is created, so a consumer
can correlate the source ruleset with the resulting domain. The
flags-only path (ruleset_fd == -1) creates no domain and emits no event.
Move the ruleset lock acquisition from landlock_merge_ruleset() to the
caller so the lock is held across both the merge and the tracepoint
emission, giving an eBPF program a consistent ruleset snapshot. Release
it before the thread-sync: holding ruleset->lock across
landlock_restrict_sibling_threads() would deadlock a sibling blocked on
the same lock. The event therefore fires before the (rare) thread-sync
failure path; when that path aborts the just-created domain, the
matching free_domain event fires so the create/free pair stays balanced.
Add a landlock_free_domain tracepoint that fires when a domain's
hierarchy node is freed. The hierarchy node is the lifecycle boundary
because it represents the domain's identity and outlives the domain's
access masks, which may still be active in descendant domains.
A domain freed without ever being committed to a credential was never
visible to user space, so free_domain is suppressed for it. This is
tracked by a new landlock_log_status value, LANDLOCK_LOG_UNCOMMITTED,
which is also the zero value so a hierarchy whose initialization failed
defaults to not observable. A hierarchy is born UNCOMMITTED and is
promoted to LANDLOCK_LOG_PENDING (or LANDLOCK_LOG_DISABLED when logging
is off) right after its create_domain event fires; a thread-sync failure
does not reset it, so an aborted domain that already emitted
create_domain still emits the matching free_domain. Promoting right
after the event, rather than at commit_creds() time, avoids a race: on a
successful thread-sync the sibling threads commit the new domain in
lockstep before landlock_restrict_self() returns, so the shared domain
may already have moved to LANDLOCK_LOG_RECORDED through a plain store,
and a late promotion would race that store and could unbalance the
domain allocation and deallocation audit records.
Cc: Günther Noack <gnoack@google.com>
Cc: Justin Suess <utilityemal77@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://patch.msgid.link/20260811094338.288094-10-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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Add the first Landlock tracepoints, for ruleset lifecycle:
landlock_create_ruleset fires from the landlock_create_ruleset() syscall
handler, and landlock_free_ruleset fires in free_ruleset() before the
ruleset is freed.
These tracepoints, and the ones added by the following commits, share a
common design. Rather than one polymorphic event distinguished by a
status field (as audit uses a shared record type with a "status="
field), each lifecycle transition and denial type gets its own event
with a type-safe TP_PROTO, giving precise ftrace filtering by event name
and type-safe eBPF access. TP_PROTO passes the object pointer and the
fields are read from it in TP_fast_assign, so an eBPF program reads the
full object state (rules, access masks, hierarchy) via BTF from a single
pointer rather than from the flattened TP_STRUCT__entry fields. The
whole cost is paid only when a tracer is attached; the static branch is
not taken otherwise. Trace fields carry the bare access-right and scope
names (read_file), reusing the audit name tables; audit prepends the
category (fs.read_file), which the trace event name already conveys.
The trace header's DOC comment documents the consistency and locking
guarantees these events share.
create_ruleset needs no lock because the ruleset is not yet shared (its
file descriptor is not yet installed). The deallocation events use the
"free_" prefix, not "drop_", because they fire when the object is
actually freed.
Add trace.c, built for CONFIG_TRACEPOINTS, which defines
CREATE_TRACE_POINTS, and extend CONFIG_SECURITY_LANDLOCK_LOG to also be
selected by CONFIG_TRACEPOINTS so the common log framework is available
to a tracepoints-only build.
Add an id field to struct landlock_ruleset, gated on CONFIG_TRACEPOINTS
and assigned from landlock_get_id_range() at creation. Only the
tracepoints consume it (audit identifies domains, not rulesets), so it
does not exist in an audit-only build. The Landlock ID is a stable u64
that names the ruleset across the trace stream and uses the same scheme
as audit, so a ruleset can be correlated between trace and audit
records.
Cc: Günther Noack <gnoack@google.com>
Cc: Justin Suess <utilityemal77@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tingmao Wang <m@maowtm.org>
Link: https://patch.msgid.link/20260811094338.288094-8-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
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