linux-kernel - Re: [PATCHv2 2/6] x86/vdso: introduce do_map_vdso() and vdso

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 6 Jul 2016 07:21:57 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Dmitry Safonov <dsafonov@...tuozzo.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dmitry Safonov <0x7f454c46@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Ingo Molnar <mingo@...hat.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>, xemul@...tuozzo.com,
	Oleg Nesterov <oleg@...hat.com>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>
Subject: Re: [PATCHv2 2/6] x86/vdso: introduce do_map_vdso() and vdso_type enum

On Wed, Jun 29, 2016 at 3:57 AM, Dmitry Safonov <dsafonov@...tuozzo.com> wrote:
> Make in-kernel API to map vDSO blobs on x86.

I think the addr calculation was already confusing and is now even
worse.  How about simplifying it?  Get rid of calculate_addr entirely
and push the vdso_addr calls into arch_setup_additional_pages, etc.
Then just use addr directly in the map_vdso code.

> +int do_map_vdso(vdso_type type, unsigned long addr, bool randomize_addr)
>  {
> -       if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
> -               return 0;
> -
> -       return map_vdso(&vdso_image_32, false);
> -}
> +       switch (type) {
> +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
> +       case VDSO_32:
> +               if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
> +                       return 0;
> +               /* vDSO aslr turned off for i386 vDSO */
> +               return map_vdso(&vdso_image_32, addr, false);
> +#endif
> +#ifdef CONFIG_X86_64
> +       case VDSO_64:
> +               if (!vdso64_enabled)
> +                       return 0;
> +               return map_vdso(&vdso_image_64, addr, randomize_addr);
> +#endif
> +#ifdef CONFIG_X86_X32_ABI
> +       case VDSO_X32:
> +               if (!vdso64_enabled)
> +                       return 0;
> +               return map_vdso(&vdso_image_x32, addr, randomize_addr);
>  #endif
> +       default:
> +               return -EINVAL;
> +       }
> +}

Why is this better than just passing the vdso_image pointer in?