From: Cary Coutant <ccoutant@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: gnu-gabi@sourceware.org
Subject: Re: Flag for late RELRO application
Date: Mon, 01 Jan 2018 00:00:00 -0000 [thread overview]
Message-ID: <CAJimCsHpn5u+=_nBQRBrHW22knS=YBtyxJQEOzfLcc=hrL7fcA@mail.gmail.com> (raw)
In-Reply-To: <0140c64d-ceef-070e-a8f5-95a930984800@redhat.com>
> I would like to add a flag to gABI (visible in the dynamic section) which
> indicates that the loader shall apply RELRO protection only after running
> the ELF constructors from DT_INIT and DT_INIT_ARRAY.
>
> This would allow applications to allocate a mapping and store a pointer to
> it in permanently read-only memory. On the mapping itself, the application
> can set the protection flags (and keys) as needed.
Why can't the application that wants to do this simply do the following?
mprotect(&ptr, sizeof(ptr), PROT_READ|PROT_WRITE);
ptr = ...;
mprotect(&ptr, sizeof(ptr), PROT_READ);
We have RELRO to collect all the data together that the dynamic loader
needs to initialize. I see no good reason to extend that feature to
support an application-specific need, especially when it significantly
expands the window during which the program is subject to attack.
Initializers are just as prone to hacking as the rest of the program.
-cary
next prev parent reply other threads:[~2018-06-11 19:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-01 0:00 Florian Weimer
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` Cary Coutant [this message]
2018-01-01 0:00 ` Florian Weimer
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