Jeremie Courreges-Anglas <[email protected]> writes:
> Theo de Raadt <[email protected]> writes:
>
>>> IIUC they would differ on OSes where libffi can't get a single mapping
>>> with both W and X access. On those OSes libffi uses a workaround, two
>>> mappings are allocated one with RW, the other with RX. While we want to
>>> disable RWX on OpenBSD as an end goal, I don't think we want to let
>>> libffi use this hack, 'cause it it basically the same as RWX.
>>
>> Yes we do.
>>
>> In general, shadow mappings are probably less attackable on a case
>> to case basis. Pure RWX mappings are worse.
>>
>> The roadmap is to remove as much RWX as possible. If we can split
>> some RWX uses off into shadow mappings, that is progress. At least
>> code using shadow mappings is half-ready for using mprotect correctly.
>
> Then the diff for src/closures.c should be different: it should ensure
> that libffi uses dlmmap_locked().
On amd64, but the diff should be MI:
=== libffi Summary ===
# of expected passes 1867
# of unexpected failures 3
Index: Makefile
===================================================================
RCS file: /cvs/ports/devel/libffi/Makefile,v
retrieving revision 1.34
diff -u -p -r1.34 Makefile
--- Makefile 23 Mar 2016 22:50:29 -0000 1.34
+++ Makefile 23 May 2016 18:38:58 -0000
@@ -3,7 +3,7 @@
COMMENT= Foreign Function Interface
DISTNAME= libffi-3.2.1
-REVISION= 1
+REVISION= 2
SHARED_LIBS += ffi 1.2 # .6.4
CATEGORIES= devel
Index: patches/patch-src_closures_c
===================================================================
RCS file: patches/patch-src_closures_c
diff -N patches/patch-src_closures_c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_closures_c 23 May 2016 18:38:58 -0000
@@ -0,0 +1,19 @@
+$OpenBSD$
+--- src/closures.c.orig Mon May 23 20:34:13 2016
++++ src/closures.c Mon May 23 20:35:56 2016
+@@ -525,6 +525,7 @@ dlmmap (void *start, size_t length, int prot,
+ printf ("mapping in %zi\n", length);
+ #endif
+
++#if 0
+ if (execfd == -1 && is_emutramp_enabled ())
+ {
+ ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset);
+@@ -543,6 +544,7 @@ dlmmap (void *start, size_t length, int prot,
+ with ((prot & ~PROT_WRITE) | PROT_EXEC) and mremap with
+ MREMAP_DUP and prot at this point. */
+ }
++#endif
+
+ if (execsize == 0 || execfd == -1)
+ {
--
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
