landlock: Add landlock_deny_access_fs and landlock_deny_access_net

2026-08-17T08:17:16+00:00

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 Cc: Justin Suess Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Steven Rostedt Cc: Tingmao Wang Link: https://patch.msgid.link/20260811094338.288094-13-mic@digikod.net Signed-off-by: Mickaël Salaün

landlock: Add create_domain and free_domain tracepoints

2026-08-17T08:17:14+00:00

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 Cc: Justin Suess Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Steven Rostedt Cc: Tingmao Wang Link: https://patch.msgid.link/20260811094338.288094-10-mic@digikod.net Signed-off-by: Mickaël Salaün

kernel/git/stable/linux.git/security/landlock/trace.h, branch master

landlock: Add landlock_deny_access_fs and landlock_deny_access_net

landlock: Add create_domain and free_domain tracepoints