Re: [PATCH v7 4/4] documentation/landlock: Adding scoping mechanism documentation
From: Mickaël Salaün <mic@digikod.net>
Date: 2024-07-25 14:24:34
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The subject should start with "landlock:" not "documentation/landlock:" See similar commits. On Wed, Jul 17, 2024 at 10:15:22PM -0600, Tahera Fahimi wrote:
- 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.
It would help to write (small) paragraphs instead of bullet points (here and for other patches).
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Signed-off-by: Tahera Fahimi <redacted> --- 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.
Here is a proposal based on your text: Complementary 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 restriction with ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``. (We also need to explain how scoping works, especially between scoped and non-scoped domains)
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+ 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
Why this change? Opened named sockets are still visible in /proc/self/fd/
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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)
"Special filesystems"? This patch series is about abstract unix socket scoping. The signal scoping one can inlcude a patch rewriting this title.
+----------------------------- + +With ABI version 6, it is possible to restrict IPC actions such as connecting to
The signal patch series may be merged with this one for the same kernel release but we should be explicit about the *current" changes. You can write this section talking only about LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, and in the signal scoping patch series you can extend this section.
+an abstract Unix socket through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks +to the ``.scoped`` ruleset attribute.
The dot is superfluous (here and in comments): "thanks to the ruleset's ``scoped`` attribute."
+ .. _kernel_support: Kernel support -- 2.34.1