[PATCH v3] landlock: Add abstract unix socket connect restriction

[Simon Horman]

On Wed, Jun 05, 2024 at 10:36:11PM -0600, Tahera Fahimi wrote:
> Abstract unix sockets are used for local inter-process communications
> without on a filesystem. Currently a sandboxed process can connect to a
> socket outside of the sandboxed environment, since landlock has no
> restriction for connecting to a unix socket in the abstract namespace.
> Access to such sockets for a sandboxed process should be scoped the same
> way ptrace is limited.
> 
> Because of compatibility reasons and since landlock should be flexible,
> we extend the user space interface by adding a new "scoped" field. This
> field optionally contains a "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" to
> specify that the ruleset will deny any connection from within the
> sandbox to its parents(i.e. any parent sandbox or non-sandbox processes)
> 
> Closes: https://github.com/landlock-lsm/linux/issues/7
> 
> Signed-off-by: Tahera Fahimi <fahimitahera at gmail.com>

...

> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> index 68625e728f43..1641aeb9eeaa 100644
> --- a/include/uapi/linux/landlock.h
> +++ b/include/uapi/linux/landlock.h
> @@ -37,6 +37,12 @@ struct landlock_ruleset_attr {
>  	 * rule explicitly allow them.
>  	 */
>  	__u64 handled_access_net;
> +	/**
> +	 * scoped: Bitmask of actions (cf. `Scope access flags`_)

nit: s/scoped: /@scoped: / 

     Flagged by ./scripts/kernel-doc -none

> +	 * that is handled by this ruleset and should be permitted
> +	 * by default if no rule explicitly deny them.
> +	 */
> +	__u64 scoped;
>  };
>  
>  /*

...