In article <20110208210049.ga8...@britannica.bec.de>,
Joerg Sonnenberger <jo...@britannica.bec.de> wrote:
>On Tue, Feb 08, 2011 at 03:34:54PM -0500, Christos Zoulas wrote:
>> Still the problem remains, how do we stack the calls to insert the ssp
>> check at the top level, without resorting to rtld tricks?
>
>Let me try to summarize the situation to make sure I get it right:
>
>The fortification code wants to provide an inline function "read" that
>calls the real "read" after doing the argument checks.
>
>rumphijack wants to override the "read" symbol, apply some magic and
>call "_sys_read" for the real system call.
Yes.
>To get the layering correct, we could make the fortification code define
>another prototype and use double rename, e.g.
>
>ssize_t __real_read(int __fd, ...) __RENAME(read);
>
>__ssp_inline ssize_t read(int __fd, ...) __RENAME(__ssp_read);
>
>__sso_inline ssize_t read(int __fd, ...) {
> __ssp_check(__buf, __lean, bos);
> return __real_read(__fd, ...);
>}
Yes, that would work. An extra level of indirection always works.
christos
