[PATCH][2.24] Drop GLIBC_TUNABLES in setxid processes

[Siddhesh Poyarekar]

I've pushed this because it is now essentially just a backport of 2/2 of
the tunables environment variable fixes.

Siddhesh

On Sunday 29 January 2017 11:41 PM, Siddhesh Poyarekar wrote:
> Drop the GLIBC_TUNABLES environment variable from the environment of
> setxid processes to avoid passing it on to non-setxid children.  This
> prevents potentially insecure tunables in the GLIBC_TUNABLES envvar
> from crossing over into a child that may use a libc that has tunables
> support.
> 
> Tested on x86_64.  If this has an ack, I'll backport it to 2.23
> and 2.22.  Distro maintainers please feel free to backport it further
> down if needed.
> 
> Siddhesh
> 
> 	* sysdeps/generic/unsecvars.h: Add GLIBC_TUNABLES.
> ---
>  sysdeps/generic/unsecvars.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
> index d5b8119..3e56538 100644
> --- a/sysdeps/generic/unsecvars.h
> +++ b/sysdeps/generic/unsecvars.h
> @@ -4,6 +4,7 @@
>  #define UNSECURE_ENVVARS \
>    "GCONV_PATH\0"							      \
>    "GETCONF_DIR\0"							      \
> +  "GLIBC_TUNABLES\0"							      \
>    "HOSTALIASES\0"							      \
>    "LD_AUDIT\0"								      \
>    "LD_DEBUG\0"								      \
>