linux-kernel - Re: [PATCH 3/9] trinity: Add load/unload IDU files

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Date:   Sat, 17 Sep 2022 16:39:07 +0900
From:   Jiho Chu <jiho.chu@...sung.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org,
        yelini.jeong@...sung.com, myungjoo.ham@...sung.com
Subject: Re: [PATCH 3/9] trinity: Add load/unload IDU files

On Wed, 27 Jul 2022 15:14:10 +0200
Greg KH <gregkh@...uxfoundation.org> wrote:

> On Mon, Jul 25, 2022 at 03:53:02PM +0900, Jiho Chu wrote:
> > +static int triv2_idu_load_file(struct trinity_driver *drv, const char *dirpath,
> > +			       const char *file_name,
> > +			       struct trinity_resv_mem *sector)
> > +{
> > +	struct device *dev = drv_to_dev_ptr(drv);
> > +	struct trinity_resv_mem mem;
> > +	char filepath[NAME_MAX];
> > +	struct kstat *stat;
> > +	struct file *filp;
> > +	loff_t pos = 0;
> > +	size_t size;
> > +	int ret;
> > +
> > +	dev = drv_to_dev_ptr(drv);
> > +	stat = vmalloc(sizeof(*stat));
> > +	if (stat == NULL)
> > +		return -ENOMEM;
> > +
> > +	/* if dirpath is null, use the default path */
> > +	if (dirpath)
> > +		snprintf(filepath, NAME_MAX, "%s/%s", dirpath, file_name);
> > +	else
> > +		snprintf(filepath, NAME_MAX, TRIV2_IDU_DIRPATH_FMT "/%s",
> > +			 utsname()->release, file_name);
> > +
> > +	filp = filp_open(filepath, O_RDONLY, 0400);
> 
> That is cute.  And totally not ok.
> 
> Please never do this, that is not how to properly load a firmware blob
> in the kernel.  This is racy and broken and probably a huge security
> hole.
> 
> Heck, I wrote an article about this very topic, way back in 2005, with
> the title of, "Things you should never do in the kernel" and can be seen
> here:
> 	https://protect2.fireeye.com/v1/url?k=9f82c8ca-ff605597-9f834385-000babd9f1ba-3ee71f9f013fb8d9&q=1&e=0963e638-a9ed-43d0-95e3-adfcbdba2425&u=https%3A%2F%2Fwww.linuxjournal.com%2Farticle%2F8110
> 
> This should not be news to anyone, again, never do this.
> 
> thanks,
> 
> greg k-h
> 

Hi, greg
I just resent second revision of the driver.
As your reference, reading user space file mechnism is changed to use IOCTL call.
And many of your reviews (abstaction, open count, doc,, ) are very helpful and fixed in the revision.
If they are modified in wrong way, please let me know.

Thanks for your review.

Thanks,
Jiho Chu