linux-kernel - Re: [PATCH 1/2] module: Restrict module namespace access to in-tree modules

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Message-ID: <20c5feae-25c0-4c8a-a40a-b35cece6c166@suse.com>
Date: Tue, 8 Jul 2025 15:03:01 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Matthias Maennich <maennich@...gle.com>, Jonathan Corbet
 <corbet@....net>, Luis Chamberlain <mcgrof@...nel.org>,
 Sami Tolvanen <samitolvanen@...gle.com>, Daniel Gomez
 <da.gomez@...sung.com>, Masahiro Yamada <masahiroy@...nel.org>,
 Nathan Chancellor <nathan@...nel.org>,
 Nicolas Schier <nicolas.schier@...ux.dev>,
 Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 Christoph Hellwig <hch@...radead.org>, Peter Zijlstra
 <peterz@...radead.org>, David Hildenbrand <david@...hat.com>,
 Shivank Garg <shivankg@....com>, "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
 Stephen Rothwell <sfr@...b.auug.org.au>, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
 linux-kbuild@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] module: Restrict module namespace access to in-tree
 modules

On 7/8/25 9:28 AM, Vlastimil Babka wrote:
> The module namespace support has been introduced to allow restricting
> exports to specific modules only, and intended for in-tree modules such
> as kvm. Make this intention explicit by disallowing out of tree modules
> both for the module loader and modpost.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> [...]
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 413ac6ea37021bc8ae260f624ca2745ed85333fc..ec7d8daa0347e3b65713396d6b6d14c2cb0270d3 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -1157,7 +1157,8 @@ static int verify_namespace_is_imported(const struct load_info *info,
>  	namespace = kernel_symbol_namespace(sym);
>  	if (namespace && namespace[0]) {
>  
> -		if (verify_module_namespace(namespace, mod->name))
> +		if (get_modinfo(info, "intree") &&
> +		    verify_module_namespace(namespace, mod->name))
>  			return 0;
>  
>  		for_each_modinfo_entry(imported_namespace, info, "import_ns") {

I'd rather avoid another walk of the modinfo data in
verify_namespace_is_imported(). I suggest checking whether mod->taints
has TAINT_OOT_MODULE set instead, which should provide the same
information. The symbol resolution already relies on the taint flags, so
this is consistent with the rest of the code.

-- 
Thanks,
Petr