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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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