linux-kernel - Re: [PATCH v7 1/4] Landlock: Add abstract unix socket connect restriction

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Message-ID: <20240725.wahChei0Hoo4@digikod.net>
Date: Thu, 25 Jul 2024 16:18:29 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Tahera Fahimi <fahimitahera@...il.com>
Cc: gnoack@...gle.com, paul@...l-moore.com, jmorris@...ei.org, 
	serge@...lyn.com, linux-security-module@...r.kernel.org, 
	linux-kernel@...r.kernel.org, bjorn3_gh@...tonmail.com, jannh@...gle.com, 
	outreachy@...ts.linux.dev, netdev@...r.kernel.org
Subject: Re: [PATCH v7 1/4] Landlock: Add abstract unix socket connect
 restriction

On Wed, Jul 17, 2024 at 10:15:19PM -0600, Tahera Fahimi wrote:
> The patch introduces a new "scoped" attribute to the
> landlock_ruleset_attr that can specify "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET"
> to scope abstract unix sockets from connecting to a process outside of
> the same landlock domain.
> 
> This patch implement two hooks, "unix_stream_connect" and "unix_may_send" to
> enforce this restriction.
> 
> Signed-off-by: Tahera Fahimi <fahimitahera@...il.com>
> 
> -------

> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index 03b470f5a85a..799a50f11d79 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -97,8 +97,9 @@ static void build_check_abi(void)
>  	 */
>  	ruleset_size = sizeof(ruleset_attr.handled_access_fs);
>  	ruleset_size += sizeof(ruleset_attr.handled_access_net);
> +	ruleset_size += sizeof(ruleset_attr.scoped);
>  	BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size);
> -	BUILD_BUG_ON(sizeof(ruleset_attr) != 16);
> +	BUILD_BUG_ON(sizeof(ruleset_attr) != 24);
>  
>  	path_beneath_size = sizeof(path_beneath_attr.allowed_access);
>  	path_beneath_size += sizeof(path_beneath_attr.parent_fd);
> @@ -149,7 +150,7 @@ static const struct file_operations ruleset_fops = {
>  	.write = fop_dummy_write,
>  };
>  
> -#define LANDLOCK_ABI_VERSION 5
> +#define LANDLOCK_ABI_VERSION 6
>  
>  /**
>   * sys_landlock_create_ruleset - Create a new ruleset
> @@ -170,7 +171,7 @@ static const struct file_operations ruleset_fops = {
>   * Possible returned errors are:
>   *
>   * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
> - * - %EINVAL: unknown @flags, or unknown access, or too small @size;
> + * - %EINVAL: unknown @flags, or unknown access, or uknown scope, or too small @size;

You'll need to rebase on top of my next branch to take into account
recent Günther's changes.

>   * - %E2BIG or %EFAULT: @attr or @size inconsistencies;
>   * - %ENOMSG: empty &landlock_ruleset_attr.handled_access_fs.
>   */