Date: Mon, 25 Apr 2011 17:02:16 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: current@freebsd.org Cc: ports@freebsd.org Subject: NX stacks on amd64 and powerpc Message-ID: <20110425140216.GI48734@deviant.kiev.zoral.com.ua>
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I added a support for non-executable stacks on amd64 and PowerPC
architectures some time ago, but did not enabled it. Passed time allowed
to fix some bugs in the implementation, and I consider it would be good
to have NX stacks enabled for architectures that support it.
I plan to commit the following knob twiddle in approximately a week.
Some ports, if any, that erronously handle PT_GNU_STACK phdr may break.
Anybody interested should and could test the change before the commit,
by setting sysctl kern.elf64.nxstack and kern.elf32.nxstack to 1.
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index b41741a..7358e40 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -116,7 +115,12 @@ static int elf_legacy_coredump =3D 0;
SYSCTL_INT(_debug, OID_AUTO, __elfN(legacy_coredump), CTLFLAG_RW,=20
&elf_legacy_coredump, 0, "");
=20
-static int __elfN(nxstack) =3D 0;
+static int __elfN(nxstack) =3D
+#if defined(__amd64__) || defined(__powerpc__) /* both 64 and 32 bit */
+ 1;
+#else
+ 0;
+#endif
SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
nxstack, CTLFLAG_RW, &__elfN(nxstack), 0,
__XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": enable non-executable sta=
ck");
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