Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Fri, 10 Dec 2021 08:57:25 +0100 | Subject | Re: [PATCH] clk: Emit a stern warning with writable debugfs enabled |
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Hi Stephen,
On Fri, Dec 10, 2021 at 2:42 AM Stephen Boyd <sboyd@kernel.org> wrote: > We don't want vendors to be enabling this part of the clk code and > shipping it to customers. Exposing the ability to change clk frequencies > and parents via debugfs is potentially damaging to the system if folks > don't know what they're doing. Emit a strong warning so that the message > is clear: don't enable this outside of development systems. > > Fixes: 37215da5553e ("clk: Add support for setting clk_rate via debugfs") > Cc: Geert Uytterhoeven <geert+renesas@glider.be> > Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Thanks for your patch!
> --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -3383,6 +3383,24 @@ static int __init clk_debug_init(void) > { > struct clk_core *core; > > +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS > + pr_warn("\n"); > + pr_warn("********************************************************************\n"); > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); > + pr_warn("** **\n"); > + pr_warn("** WRITEABLE clk DebugFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL **\n"); > + pr_warn("** **\n"); > + pr_warn("** This means that this kernel is built to expose clk operations **\n"); > + pr_warn("** such as parent or rate setting, enabling, disabling, etc. **\n"); > + pr_warn("** to userspace, which may compromise security on your system. **\n"); > + pr_warn("** **\n"); > + pr_warn("** If you see this message and you are not debugging the **\n"); > + pr_warn("** kernel, report this immediately to your vendor! **\n"); > + pr_warn("** **\n"); > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); > + pr_warn("********************************************************************\n");
So how many variants of such blocks do we have now in the kernel?
> +#endif > + > rootdir = debugfs_create_dir("clk", NULL); > > debugfs_create_file("clk_summary", 0444, rootdir, &all_lists, > > base-commit: fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf > prerequisite-patch-id: e0d3f8e3fa43b55e55d7c4cee7c4902ae06ea4e0 > -- > https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/ > https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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