[PATCH v7 4/4] documentation/landlock: Adding scoping mechanism documentation

[Tahera Fahimi]

- Defining ABI version 6 that supports IPC restriction.
- Adding "scoped" to the "Access rights".
- In current limitation, unnamed sockets are specified as
  sockets that are not restricted.

Signed-off-by: Tahera Fahimi <fahimitahera at gmail.com>
---
 Documentation/userspace-api/landlock.rst | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
index 07b63aec56fa..61b91cc03560 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: April 2024
+:Date: July 2024
 
 The goal of Landlock is to enable to restrict ambient rights (e.g. global
 filesystem or network access) for a set of processes.  Because Landlock
@@ -306,6 +306,16 @@ To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target
 process, a sandboxed process should have a subset of the target process rules,
 which means the tracee must be in a sub-domain of the tracer.
 
+IPC Scoping
+-----------
+
+Similar to Ptrace, a sandboxed process should not be able to access the resources
+(like abstract unix sockets, or signals) outside of the sandbox domain. For example,
+a sandboxed process should not be able to :manpage:`connect(2)` to a non-sandboxed
+process through abstract unix sockets (:manpage:`unix(7)`). This restriction is
+applicable by optionally specifying ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET`` in
+the ruleset.
+
 Truncating files
 ----------------
 
@@ -404,7 +414,7 @@ Access rights
 -------------
 
 .. kernel-doc:: include/uapi/linux/landlock.h
-    :identifiers: fs_access net_access
+    :identifiers: fs_access net_access scoped
 
 Creating a new ruleset
 ----------------------
@@ -446,7 +456,7 @@ Special filesystems
 
 Access to regular files and directories can be restricted by Landlock,
 according to the handled accesses of a ruleset.  However, files that do not
-come from a user-visible filesystem (e.g. pipe, socket), but can still be
+come from a user-visible filesystem (e.g. pipe, unnamed socket), but can still be
 accessed through ``/proc/<pid>/fd/*``, cannot currently be explicitly
 restricted.  Likewise, some special kernel filesystems such as nsfs, which can
 be accessed through ``/proc/<pid>/ns/*``, cannot currently be explicitly
@@ -541,6 +551,13 @@ earlier ABI.
 Starting with the Landlock ABI version 5, it is possible to restrict the use of
 :manpage:`ioctl(2)` using the new ``LANDLOCK_ACCESS_FS_IOCTL_DEV`` right.
 
+Special filesystems (ABI < 6)
+-----------------------------
+
+With ABI version 6, it is possible to restrict IPC actions such as connecting to
+an abstract Unix socket through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks
+to the ``.scoped`` ruleset attribute.
+
 .. _kernel_support:
 
 Kernel support
-- 
2.34.1