linux-kernel - Re: [RFC][PATCH] exec: Use init rlimits for setuid exec

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: <20170710181600.GG7071@dhcp22.suse.cz>
Date:   Mon, 10 Jul 2017 20:16:00 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Ben Hutchings <ben@...adent.org.uk>, Willy Tarreau <w@....eu>,
        Hugh Dickins <hughd@...gle.com>,
        Oleg Nesterov <oleg@...hat.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Tony Luck <tony.luck@...el.com>,
        "James E.J. Bottomley" <jejb@...isc-linux.org>,
        Helge Diller <deller@....de>,
        James Hogan <james.hogan@...tec.com>,
        Laura Abbott <labbott@...hat.com>, Greg KH <greg@...ah.com>,
        "security@...nel.org" <security@...nel.org>,
        Qualys Security Advisory <qsa@...lys.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ximin Luo <infinity0@...ian.org>
Subject: Re: [RFC][PATCH] exec: Use init rlimits for setuid exec

On Mon 10-07-17 18:27:51, Michal Hocko wrote:
> On Mon 10-07-17 09:12:11, Kees Cook wrote:
[...]
> > >> do_execveat_common() ->
> > >> exec_binprm() ->
> > >> search_binary_handler() ->
> > >> fmt->load_binary (load_elf_binary()) ->
> > >> setup_new_exec() ->
> > >> arch_pick_mmap_layout() ->
> > >> mmap_is_legacy() ->
> > >> rlimit(RLIMIT_STACK) == RLIM_INFINITY
> > >
> > > FWIW this is gone in tip tree. See
> > > lkml.kernel.org/r/20170614082218.12450-1-mhocko@...nel.org
> > 
> > Sounds good to me, but won't large-memory users in 32-bit get annoyed?
> 
> Why would they? 32b do bottom up layouts by default.

OK, I misread the code. 32b applications on 64b systems do top down by
default and only if they override this by ADDR_COMPAT_LAYOUT
personality. For some reason I thought that 32b userspace goes a
different path and makes sure that they are always doing bottom up.

Anyway even if somebody really needs to grow stack really large we have
the personality to give them the legacy layout.
-- 
Michal Hocko
SUSE Labs