linux-hardening - Re: [PATCH 2/5] codetag: Run module

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Message-ID: <CAJuCfpFY9=NOftvaKqkuohZH9L1QTHshORXeqLomrHBPPTd9kw@mail.gmail.com>
Date: Thu, 29 Aug 2024 08:02:13 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Kees Cook <kees@...nel.org>
Cc: Vlastimil Babka <vbabka@...e.cz>, Kent Overstreet <kent.overstreet@...ux.dev>, 
	Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, 
	Joonsoo Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org, 
	"GONG, Ruiqi" <gongruiqi@...weicloud.com>, Jann Horn <jannh@...gle.com>, 
	Matteo Rizzo <matteorizzo@...gle.com>, jvoisin <julien.voisin@...tri.org>, 
	Xiu Jianfeng <xiujianfeng@...wei.com>, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH 2/5] codetag: Run module_load hooks for builtin codetags

On Fri, Aug 9, 2024 at 12:33 AM Kees Cook <kees@...nel.org> wrote:
>
> The module_load callback should still run for builtin codetags that
> define it, even in a non-modular kernel. (i.e. for the cmod->mod == NULL
> case).
>
> Signed-off-by: Kees Cook <kees@...nel.org>

Hi Kees,
I finally got some time and started reviewing your patches.
Coincidentally I recently posted a fix for this issue at
https://lore.kernel.org/all/20240828231536.1770519-1-surenb@google.com/
Your fix is missing a small part when codetag_module_init() is using
mod->name while struct module is undefined (CONFIG_MODULES=n) and you
should see this build error:

In file included from ./include/linux/kernel.h:31,
                 from ./include/linux/cpumask.h:11,
                 from ./include/linux/smp.h:13,
                 from ./include/linux/lockdep.h:14,
                 from ./include/linux/radix-tree.h:14,
                 from ./include/linux/idr.h:15,
                 from lib/codetag.c:3:
lib/codetag.c: In function ‘codetag_module_init’:
  CC      drivers/acpi/acpica/extrace.o
lib/codetag.c:167:34: error: invalid use of undefined type ‘struct module’
  167 |                         mod ? mod->name : "(built-in)");
      |                                  ^~

Thanks,
Suren.


> ---
> Cc: Suren Baghdasaryan <surenb@...gle.com>
> Cc: Kent Overstreet <kent.overstreet@...ux.dev>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: Pekka Enberg <penberg@...nel.org>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Roman Gushchin <roman.gushchin@...ux.dev>
> Cc: Hyeonggon Yoo <42.hyeyoo@...il.com>
> Cc: linux-mm@...ck.org
> ---
>  lib/codetag.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/lib/codetag.c b/lib/codetag.c
> index 5ace625f2328..ef7634c7ee18 100644
> --- a/lib/codetag.c
> +++ b/lib/codetag.c
> @@ -125,7 +125,6 @@ static inline size_t range_size(const struct codetag_type *cttype,
>                         cttype->desc.tag_size;
>  }
>
> -#ifdef CONFIG_MODULES
>  static void *get_symbol(struct module *mod, const char *prefix, const char *name)
>  {
>         DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN);
> @@ -199,6 +198,7 @@ static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
>         return 0;
>  }
>
> +#ifdef CONFIG_MODULES
>  void codetag_load_module(struct module *mod)
>  {
>         struct codetag_type *cttype;
> @@ -248,9 +248,6 @@ bool codetag_unload_module(struct module *mod)
>
>         return unload_ok;
>  }
> -
> -#else /* CONFIG_MODULES */
> -static int codetag_module_init(struct codetag_type *cttype, struct module *mod) { return 0; }
>  #endif /* CONFIG_MODULES */
>
>  struct codetag_type *
> --
> 2.34.1
>