linux-kernel - Re: [PATCH v9 4/5] sample/Landlock: Support abstract unix socket restriction

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Message-ID: <20240819.Ielaingoo8Yi@digikod.net>
Date: Mon, 19 Aug 2024 21:47:50 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Tahera Fahimi <fahimitahera@...il.com>
Cc: outreachy@...ts.linux.dev, 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, 
	netdev@...r.kernel.org
Subject: Re: [PATCH v9 4/5] sample/Landlock: Support abstract unix socket
 restriction

On Wed, Aug 14, 2024 at 12:22:22AM -0600, Tahera Fahimi wrote:
> A sandboxer can receive the character "a" as input from the environment
> variable LL_SCOPE to restrict the abstract unix sockets from connecting
> to a process outside its scoped domain.
> 
> Example
> =======
> Create an abstract unix socket to listen with socat(1):
> socat abstract-listen:mysocket -
> Create a sandboxed shell and pass the character "a" to LL_SCOPED:
> LL_FS_RO=/ LL_FS_RW=. LL_SCOPED="a" ./sandboxer /bin/bash
> If the sandboxed process tries to connect to the listening socket
> with command "socat - abstract-connect:mysocket", the connection
> will fail.
> 
> Signed-off-by: Tahera Fahimi <fahimitahera@...il.com>
> ---

> @@ -358,6 +403,11 @@ int main(const int argc, char *const argv[], char *const *const envp)
>  			~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>  	}
>  
> +	if (abi >= 6 && !check_ruleset_scope(ENV_SCOPED_NAME, &ruleset_attr)) {
> +		perror("Unsupported IPC scoping requested");

If LL_SCOPE="", the sandboxer prints:
"Unsupported IPC scoping requested: Success"

> +		return 1;
> +	}
> +
>  	ruleset_fd =
>  		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>  	if (ruleset_fd < 0) {
> -- 
> 2.34.1
> 
>