linux-kernel - Re: [PATCH 04/12] module: move early sanity checks into a helper

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Message-ID: <ZB3s+Hn2j6HMIe+m@bombadil.infradead.org>
Date:   Fri, 24 Mar 2023 11:33:28 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Petr Pavlu <petr.pavlu@...e.com>
Cc:     christophe.leroy@...roup.eu, song@...nel.org,
        linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org,
        pmladek@...e.com, david@...hat.com, prarit@...hat.com
Subject: Re: [PATCH 04/12] module: move early sanity checks into a helper

On Fri, Mar 24, 2023 at 02:02:06PM +0100, Petr Pavlu wrote:
> On 3/19/23 22:27, Luis Chamberlain wrote:
> > Move early sanity checkers for the module into a helper.
> > This let's us make it clear when we are working with the
> > local copy of the module prior to allocation.
> > 
> > This produces no functional changes, it just makes subsequent
> > changes easier to read.
> > 
> > Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> > ---
> >  kernel/module/main.c | 43 ++++++++++++++++++++++++++-----------------
> >  1 file changed, 26 insertions(+), 17 deletions(-)
> > 
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index 427284ab31f1..933cef72ae13 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -2668,6 +2668,31 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname,
> >  	return 0;
> >  }
> >  
> > +/* Module within temporary copy, this doesn't do any allocation  */
> > +static int early_mod_check(struct load_info *info, int flags)
> > +{
> > +	int err;
> > +
> > +	/*
> > +	 * Now that we know we have the correct module name, check
> > +	 * if it's blacklisted.
> > +	 */
> > +	if (blacklisted(info->name)) {
> > +		pr_err("Module %s is blacklisted\n", info->name);
> > +		return -EPERM;
> > +	}
> > +
> > +	err = rewrite_section_headers(info, flags);
> > +	if (err)
> > +		return err;
> > +
> > +	/* Check module struct version now, before we try to use module. */
> > +	if (!check_modstruct_version(info, info->mod))
> > +		return ENOEXEC;
> 
> The error value when check_modstruct_version() fails is changed in this patch
> from -ENOEXEC to ENOEXEC and updated back again in the next patch. It would be
> good to avoid introducing this temporary problem and keep the value throughout
> as -ENOEXEC.

Fixed, thanks.

  Luis