@@ -8,7 +8,7 @@ Landlock: unprivileged access control
=====================================
:Author: Mickaël Salaün
-:Date: July 2024
+:Date: August 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
@@ -82,7 +82,8 @@ to be explicit about the denied-by-default access rights.
LANDLOCK_ACCESS_NET_BIND_TCP |
LANDLOCK_ACCESS_NET_CONNECT_TCP,
.scoped =
- LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET,
+ LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET |
+ LANDLOCK_SCOPED_SIGNAL,
};
Because we may not know on which kernel version an application will be
@@ -123,7 +124,8 @@ version, and only use the available subset of access rights:
ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV;
case 5:
/* Removes LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET for ABI < 6 */
- ruleset_attr.scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET;
+ ruleset_attr.scoped &= ~(LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET |
+ LANDLOCK_SCOPED_SIGNAL);
}
This enables to create an inclusive ruleset that will contain our rules.
@@ -319,11 +321,14 @@ 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 restriction
-with ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``.
+with ``LANDLOCK_SCOPED_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_SCOPED_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 processes in
-the same scoped domain.
+A sandboxed process can access to a non-sandboxed process when its domain is
+not scoped. If a process's domain is scoped, it can only access to processes in
+the same scoped domain. For example, If a process is scoped to send signal to
+other processes, it can only send signals to processes in the same scoped domain.
IPC scoping does not support Landlock rules, so if a domain is scoped, no rules
can be added to allow accessing to a resource outside of the scoped domain.
@@ -563,12 +568,12 @@ 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.
-Abstract Unix sockets Restriction (ABI < 6)
---------------------------------------------
+Abstract Unix sockets and Signal Restriction (ABI < 6)
+-------------------------------------------------------
With ABI version 6, it is possible to restrict connection to an abstract Unix socket
-through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks to the ``scoped`` ruleset
-attribute.
+through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET`` and sending signal through
+``LANDLOCK_SCOPED_SIGNAL``, thanks to the ``scoped`` ruleset attribute.
.. _kernel_support:
Improving Landlock ABI version 6 to support signal scoping with LANDLOCK_SCOPED_SIGNAL. Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com> --- Documentation/userspace-api/landlock.rst | 27 ++++++++++++++---------- 1 file changed, 16 insertions(+), 11 deletions(-)