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Date: Wed, 15 Mar 2017 23:57:49 +0100
From: Jilles Tjoelker <jilles@stack.nl>
To: Konstantin Belousov <kib@FreeBSD.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r315331 - in head/libexec/rtld-elf: . aarch64 amd64
 arm i386 mips powerpc powerpc64 riscv sparc64
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On Wed, Mar 15, 2017 at 09:11:58PM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Wed Mar 15 21:11:57 2017
> New Revision: 315331
> URL: https://svnweb.freebsd.org/changeset/base/315331

> Log:
>   Implement LD_BIND_NOT knob for rtld.

>   From the manpage:
>   When set to a nonempty string, prevents modifications of the PLT slots
>   when doing bindings.  As result, each call of the PLT-resolved
>   function is resolved.  In combination with debug output, this provides
>   complete account of all bind actions at runtime.

>   Same feature exists on Linux and Solaris.

Since this feature heavily affects timing (possibly making race
conditions easier to exploit) and may prevent making parts of the GOT
read-only, it seems a good idea to treat this environment variable as
dangerous for setuid and setgid processes.

-- 
Jilles Tjoelker