Merge tag 'landlock-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock updates from Mickaël Salaün:
 "This brings two main changes to Landlock:

   - A signal scoping fix with a new interface for user space to know if
     it is compatible with the running kernel.

   - Audit support to give visibility on why access requests are denied,
     including the origin of the security policy, missing access rights,
     and description of object(s). This was designed to limit log spam
     as much as possible while still alerting about unexpected blocked
     access.

  With these changes come new and improved documentation, and a lot of
  new tests"

* tag 'landlock-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: (36 commits)
  landlock: Add audit documentation
  selftests/landlock: Add audit tests for network
  selftests/landlock: Add audit tests for filesystem
  selftests/landlock: Add audit tests for abstract UNIX socket scoping
  selftests/landlock: Add audit tests for ptrace
  selftests/landlock: Test audit with restrict flags
  selftests/landlock: Add tests for audit flags and domain IDs
  selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags
  selftests/landlock: Add test for invalid ruleset file descriptor
  samples/landlock: Enable users to log sandbox denials
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_*_EXEC_* flags
  landlock: Log scoped denials
  landlock: Log TCP bind and connect denials
  landlock: Log truncate and IOCTL denials
  landlock: Factor out IOCTL hooks
  landlock: Log file-related denials
  landlock: Log mount-related denials
  landlock: Add AUDIT_LANDLOCK_DOMAIN and log domain status
  landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials
  ...

1 files changed, 44 insertions, 28 deletions

diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
index ad587f53fe41..1d0c2c15c22e 100644
--- a/Documentation/userspace-api/landlock.rst
+++ b/Documentation/userspace-api/landlock.rst
@@ -8,7 +8,7 @@ Landlock: unprivileged access control
 =====================================
 
 :Author: Mickaël Salaün
-:Date: January 2025
+:Date: March 2025
 
 The goal of Landlock is to enable restriction of ambient rights (e.g. global
 filesystem or network access) for a set of processes.  Because Landlock
@@ -317,33 +317,32 @@ IPC scoping
 -----------
 
 Similar to the implicit `Ptrace restrictions`_, we may want to further restrict
-interactions between sandboxes. Each Landlock domain can be explicitly scoped
-for a set of actions by specifying it on a ruleset.  For example, if a
-sandboxed process should not be able to :manpage:`connect(2)` to a
-non-sandboxed process through abstract :manpage:`unix(7)` sockets, we can
-specify such a restriction with ``LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET``.
-Moreover, if a sandboxed process should not be able to send a signal to a
-non-sandboxed process, we can specify this restriction with
-``LANDLOCK_SCOPE_SIGNAL``.
-
-A sandboxed process can connect to a non-sandboxed process when its domain is
-not scoped. If a process's domain is scoped, it can only connect to sockets
-created by processes in the same scope.
-Moreover, if a process is scoped to send signal to a non-scoped process, it can
-only send signals to processes in the same scope.
-
-A connected datagram socket behaves like a stream socket when its domain is
-scoped, meaning if the domain is scoped after the socket is connected, it can
-still :manpage:`send(2)` data just like a stream socket.  However, in the same
-scenario, a non-connected datagram socket cannot send data (with
-:manpage:`sendto(2)`) outside its scope.
-
-A process with a scoped domain can inherit a socket created by a non-scoped
-process. The process cannot connect to this socket since it has a scoped
-domain.
-
-IPC scoping does not support exceptions, so if a domain is scoped, no rules can
-be added to allow access to resources or processes outside of the scope.
+interactions between sandboxes.  Therefore, at ruleset creation time, each
+Landlock domain can restrict the scope for certain operations, so that these
+operations can only reach out to processes within the same Landlock domain or in
+a nested Landlock domain (the "scope").
+
+The operations which can be scoped are:
+
+``LANDLOCK_SCOPE_SIGNAL``
+    This limits the sending of signals to target processes which run within the
+    same or a nested Landlock domain.
+
+``LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET``
+    This limits the set of abstract :manpage:`unix(7)` sockets to which we can
+    :manpage:`connect(2)` to socket addresses which were created by a process in
+    the same or a nested Landlock domain.
+
+    A :manpage:`sendto(2)` on a non-connected datagram socket is treated as if
+    it were doing an implicit :manpage:`connect(2)` and will be blocked if the
+    remote end does not stem from the same or a nested Landlock domain.
+
+    A :manpage:`sendto(2)` on a socket which was previously connected will not
+    be restricted.  This works for both datagram and stream sockets.
+
+IPC scoping does not support exceptions via :manpage:`landlock_add_rule(2)`.
+If an operation is scoped within a domain, no rules can be added to allow access
+to resources or processes outside of the scope.
 
 Truncating files
 ----------------
@@ -595,6 +594,16 @@ Starting with the Landlock ABI version 6, it is possible to restrict
 :manpage:`signal(7)` sending by setting ``LANDLOCK_SCOPE_SIGNAL`` to the
 ``scoped`` ruleset attribute.
 
+Logging (ABI < 7)
+-----------------
+
+Starting with the Landlock ABI version 7, it is possible to control logging of
+Landlock audit events with the ``LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF``,
+``LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON``, and
+``LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF`` flags passed to
+sys_landlock_restrict_self().  See Documentation/admin-guide/LSM/landlock.rst
+for more details on audit.
+
 .. _kernel_support:
 
 Kernel support
@@ -683,9 +692,16 @@ fine-grained restrictions).  Moreover, their complexity can lead to security
 issues, especially when untrusted processes can manipulate them (cf.
 `Controlling access to user namespaces <https://lwn.net/Articles/673597/>`_).
 
+How to disable Landlock audit records?
+--------------------------------------
+
+You might want to put in place filters as explained here:
+Documentation/admin-guide/LSM/landlock.rst
+
 Additional documentation
 ========================
 
+* Documentation/admin-guide/LSM/landlock.rst
 * Documentation/security/landlock.rst
 * https://landlock.io