As promised in the --enable-host-pie patch, this patch adds another
configure option, --enable-host-bind-now, which adds -z now when linking
the compiler executables in order to extend hardening. BIND_NOW with RELRO
allows the GOT to be marked RO; this prevents GOT modification attacks.
This option does not affect linking of target libraries; you can use
LDFLAGS_FOR_TARGET=-Wl,-z,relro,-z,now to enable RELRO/BIND_NOW.
With this patch:
$ readelf -Wd cc1{,plus,obj,gm2} f951 lto1 cpp rust1 gnat1 | grep FLAGS
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
0x000000000000001e (FLAGS) BIND_NOW
0x000000006ffffffb (FLAGS_1) Flags: NOW PIE
c++tools/ChangeLog:
* configure.ac (--enable-host-bind-now): New check.
* configure: Regenerate.
gcc/ChangeLog:
* configure.ac (--enable-host-bind-now): New check. Add
-Wl,-z,now to LD_PICFLAG if --enable-host-bind-now.
* configure: Regenerate.
* doc/install.texi: Document --enable-host-bind-now.
lto-plugin/ChangeLog:
* configure.ac (--enable-host-bind-now): New check. Link with
-z,now.
* configure: Regenerate.