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Diffstat (limited to 'Documentation/userspace-api/landlock.rst')
| -rw-r--r-- | Documentation/userspace-api/landlock.rst | 72 |
1 files changed, 44 insertions, 28 deletions
diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst index d639c61cb472..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: October 2024 +: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 |