linux-kernel - Re: [PATCH] modules: always page-align module section allocations

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]

Message-ID: <CAMRc=MeZOgY=qHNZf635i1OOnrx6Rh2D1qTSBPQjk_CGrRo-Tg@mail.gmail.com>
Date:   Thu, 25 Jul 2019 09:08:32 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Jessica Yu <jeyu@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Jian Cheng <cj.chengjian@...wei.com>,
        Nadav Amit <namit@...are.com>, Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        David Lechner <david@...hnology.com>,
        Adam Ford <aford173@...il.com>, Martin Kaiser <lists@...ser.cx>
Subject: Re: [PATCH] modules: always page-align module section allocations

śr., 24 lip 2019 o 17:02 Jessica Yu <jeyu@...nel.org> napisał(a):
>
> Some arches (e.g., arm64, x86) have moved towards non-executable
> module_alloc() allocations for security hardening reasons. That means
> that the module loader will need to set the text section of a module to
> executable, regardless of whether or not CONFIG_STRICT_MODULE_RWX is set.
>
> When CONFIG_STRICT_MODULE_RWX=y, module section allocations are always
> page-aligned to handle memory rwx permissions. On some arches with
> CONFIG_STRICT_MODULE_RWX=n however, when setting the module text to
> executable, the BUG_ON() in frob_text() gets triggered since module
> section allocations are not page-aligned when CONFIG_STRICT_MODULE_RWX=n.
> Since the set_memory_* API works with pages, and since we need to call
> set_memory_x() regardless of whether CONFIG_STRICT_MODULE_RWX is set, we
> might as well page-align all module section allocations for ease of
> managing rwx permissions of module sections (text, rodata, etc).
>
> Fixes: 2eef1399a866 ("modules: fix BUG when load module with rodata=n")
> Reported-by: Martin Kaiser <lists@...ser.cx>
> Reported-by: Bartosz Golaszewski <brgl@...ev.pl>
> Tested-by: David Lechner <david@...hnology.com>
> Tested-by: Martin Kaiser <martin@...ser.cx>
> Signed-off-by: Jessica Yu <jeyu@...nel.org>
> ---
>  kernel/module.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 5933395af9a0..cd8df516666d 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -64,14 +64,9 @@
>
>  /*
>   * Modules' sections will be aligned on page boundaries
> - * to ensure complete separation of code and data, but
> - * only when CONFIG_STRICT_MODULE_RWX=y
> + * to ensure complete separation of code and data
>   */
> -#ifdef CONFIG_STRICT_MODULE_RWX
>  # define debug_align(X) ALIGN(X, PAGE_SIZE)
> -#else
> -# define debug_align(X) (X)
> -#endif
>
>  /* If this is set, the section belongs in the init part of the module */
>  #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
> --
> 2.16.4
>

Tested-by: Bartosz Golaszewski <bgolaszewski@...libre.com>