so we cannot compile it with -fstack-protector[-all] flags (or
it will self-recurse); this is ensured in sys/conf/files. This
OTOH means that checking for defines __SSP__ and __SSP_ALL__ to
determine if we should be compiling the support is impossible
(which it was trying, resulting in an empty object file). Fix
this by always compiling the symbols in this files. It's good
because it allows us to always have SSP support, and then compile
with SSP selectively.
Repoted by: tinderbox
- It is opt-out for now so as to give it maximum testing, but it may be
turned opt-in for stable branches depending on the consensus. You
can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
It is harmless to steal the knob as SSP symbols have been provided
by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
(sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
libc will be automatically downgraded to -fstack-protector because it
breaks rtld otherwise.
- This option is unavailable on ia64.
Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.
Submitted by: Jeremie Le Hen <jeremie@le-hen.org>
