- djm@cvs.openbsd.org 2011/06/22 21:57:01
[servconf.c servconf.h sshd.c sshd_config.5 sandbox-rlimit.c]
[sandbox-systrace.c sandbox.h configure.ac Makefile.in]
introduce sandboxing of the pre-auth privsep child using systrace(4).
This introduces a new "UsePrivilegeSeparation=sandbox" option for
sshd_config that applies mandatory restrictions on the syscalls the
privsep child can perform. This prevents a compromised privsep child
from being used to attack other hosts (by opening sockets and proxying)
or probing local kernel attack surface.
The sandbox is implemented using systrace(4) in unsupervised "fast-path"
mode, where a list of permitted syscalls is supplied. Any syscall not
on the list results in SIGKILL being sent to the privsep child. Note
that this requires a kernel with the new SYSTR_POLICY_KILL option.
UsePrivilegeSeparation=sandbox will become the default in the future
so please start testing it now.
feedback dtucker@; ok markus@
diff --git a/configure.ac b/configure.ac
index 8f36338..380a8b9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-# $Id: configure.ac,v 1.476 2011/06/03 02:11:38 djm Exp $
+# $Id: configure.ac,v 1.477 2011/06/22 22:30:03 djm Exp $
#
# Copyright (c) 1999-2004 Damien Miller
#
@@ -15,7 +15,7 @@
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
AC_INIT([OpenSSH], [Portable], [openssh-unix-dev@mindrot.org])
-AC_REVISION($Revision: 1.476 $)
+AC_REVISION($Revision: 1.477 $)
AC_CONFIG_SRCDIR([ssh.c])
AC_LANG([C])
@@ -106,6 +106,16 @@
AC_C_INLINE
AC_CHECK_DECL([LLONG_MAX], [have_llong_max=1], , [#include <limits.h>])
+AC_CHECK_DECL([SYSTR_POLICY_KILL], [have_systr_policy_kill=1], , [
+ #include <sys/types.h>
+ #include <sys/param.h>
+ #include <dev/systrace.h>
+])
+AC_CHECK_DECL([RLIMIT_NPROC],
+ [AC_DEFINE([HAVE_RLIMIT_NPROC], [], [sys/resource.h has RLIMIT_NPROC])], , [
+ #include <sys/types.h>
+ #include <sys/resource.h>
+])
use_stack_protector=1
AC_ARG_WITH([stackprotect],
@@ -2461,6 +2471,34 @@
[non-privileged user for privilege separation])
AC_SUBST([SSH_PRIVSEP_USER])
+# Decide which sandbox style to use
+sandbox_arg=""
+AC_ARG_WITH([sandbox],
+ [ --with-sandbox=style Specify privilege separation sandbox (no, rlimit, systrace)],
+ [
+ if test "x$withval" = "xyes" ; then
+ sandbox_arg=""
+ else
+ sandbox_arg="$withval"
+ fi
+ ]
+)
+if test "x$sandbox_arg" = "xsystrace" || \
+ ( test -z "$sandbox_arg" && test "x$have_systr_policy_kill" = "x1" ) ; then
+ SANDBOX_STYLE="systrace"
+ AC_DEFINE([SANDBOX_SYSTRACE], [1], [Sandbox using systrace(4)])
+elif test "x$sandbox_arg" = "xrlimit" || \
+ ( test -z "$sandbox_arg" && test "x$ac_cv_func_setrlimit" = "xyes" ) ; then
+ SANDBOX_STYLE="rlimit"
+ AC_DEFINE([SANDBOX_RLIMIT], [1], [Sandbox using setrlimit(2)])
+elif test -z "$sandbox_arg" || test "x$sandbox_arg" = "xno" || \
+ test "x$sandbox_arg" = "xnone" || test "x$sandbox_arg" = "xnull" ; then
+ SANDBOX_STYLE="none"
+ AC_DEFINE([SANDBOX_NULL], [1], [no privsep sandboxing])
+else
+ AC_MSG_ERROR([unsupported -with-sandbox])
+fi
+
# Cheap hack to ensure NEWS-OS libraries are arranged right.
if test ! -z "$SONY" ; then
LIBS="$LIBS -liberty";
@@ -4191,6 +4229,7 @@
echo " Translate v4 in v6 hack: $IPV4_IN6_HACK_MSG"
echo " BSD Auth support: $BSD_AUTH_MSG"
echo " Random number source: $RAND_MSG"
+echo " Privsep sandbox style: $SANDBOX_STYLE"
echo ""