On Thu, 23 Jun 2011, Damien Miller wrote:
>
> Hi,
>
> The systrace and rlimit sandboxes have been committed and will be in
> snapshots dated 20110623 and later. This diff adds support for
> pre-auth privsep sandboxing using the OS X sandbox_init(3) service.
>
> It's a bit disappointing that the OS X developers chose such as
> namespace-polluting header and function names "sandbox.h",
> "sandbox_init()", etc. It already forced me to rename a header in
> OpenSSH.
>
> Anyway, the OS X sandbox uses the strictest of the canned policies:
> "kSBXProfilePureComputation". It passes regress tests and seems
to
> deny calls to fork() as expected. Barring objections, I'll commit
> this soon - please test.
Markus points out that, despite its name, the kSBXProfilePureComputation
sandbox actually allows the sandboxed process to create sockets (WTH?).
So here is a revised version of the diff that uses setrlimit() to
prevent that too.
-d
Index: ChangeLog
==================================================================RCS file:
/var/cvs/openssh/ChangeLog,v
retrieving revision 1.5912
diff -u -p -r1.5912 ChangeLog
--- ChangeLog 23 Jun 2011 09:45:51 -0000 1.5912
+++ ChangeLog 23 Jun 2011 23:41:14 -0000
@@ -1,3 +1,7 @@
+20110624
+ - (djm) [configure.ac Makefile.in sandbox-darwin.c] Add a sandbox for
+ Darwin/OS X using sandbox_init() + setrlimit()
+
20110623
- OpenBSD CVS Sync
- djm at cvs.openbsd.org 2011/06/22 21:47:28
Index: Makefile.in
==================================================================RCS file:
/var/cvs/openssh/Makefile.in,v
retrieving revision 1.323
diff -u -p -r1.323 Makefile.in
--- Makefile.in 22 Jun 2011 22:30:03 -0000 1.323
+++ Makefile.in 23 Jun 2011 22:33:38 -0000
@@ -90,7 +90,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passw
loginrec.o auth-pam.o auth-shadow.o auth-sia.o md5crypt.o \
sftp-server.o sftp-common.o \
roaming_common.o roaming_serv.o \
- sandbox-null.o sandbox-rlimit.o sandbox-systrace.o
+ sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o
MANPAGES = moduli.5.out scp.1.out ssh-add.1.out ssh-agent.1.out
ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out
sftp.1.out ssh-keysign.8.out ssh-pkcs11-helper.8.out sshd_config.5.out
ssh_config.5.out
MANPAGES_IN = moduli.5 scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1
ssh.1 sshd.8 sftp-server.8 sftp.1 ssh-keysign.8 ssh-pkcs11-helper.8
sshd_config.5 ssh_config.5
Index: configure.ac
==================================================================RCS file:
/var/cvs/openssh/configure.ac,v
retrieving revision 1.477
diff -u -p -r1.477 configure.ac
--- configure.ac 22 Jun 2011 22:30:03 -0000 1.477
+++ configure.ac 23 Jun 2011 22:33:38 -0000
@@ -525,6 +525,8 @@ main() { if (NSVersionOfRunTimeLibrary("
AC_DEFINE([SPT_TYPE], [SPT_REUSEARGV],
[Define to a Set Process Title type if your system is
supported by bsd-setproctitle.c])
+ AC_CHECK_FUNCS([sandbox_init])
+ AC_CHECK_HEADERS([sandbox.h])
;;
*-*-dragonfly*)
SSHDLIBS="$SSHDLIBS -lcrypt"
@@ -2487,6 +2489,11 @@ if test "x$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$sandbox_arg" = "xdarwin" || \
+ ( test -z "$sandbox_arg" && test
"x$ac_cv_func_sandbox_init" = "xyes" && \
+ test "x$ac_cv_header_sandbox_h" = "xyes") ; then
+ SANDBOX_STYLE="darwin"
+ AC_DEFINE([SANDBOX_DARWIN], [1], [Sandbox using Darwin sandbox_init(3)])
elif test "x$sandbox_arg" = "xrlimit" || \
( test -z "$sandbox_arg" && test
"x$ac_cv_func_setrlimit" = "xyes" ) ; then
SANDBOX_STYLE="rlimit"
Index: sandbox-darwin.c
==================================================================RCS file:
sandbox-darwin.c
diff -N sandbox-darwin.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sandbox-darwin.c 23 Jun 2011 22:36:07 -0000
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2011 Damien Miller <djm at mindrot.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "includes.h"
+
+#ifdef SANDBOX_DARWIN
+
+#include <sys/types.h>
+
+#include <sandbox.h>
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "sandbox.h"
+#include "xmalloc.h"
+
+/* Darwin/OS X sandbox */
+
+struct ssh_sandbox {
+ pid_t child_pid;
+};
+
+struct ssh_sandbox *
+ssh_sandbox_init(void)
+{
+ struct ssh_sandbox *box;
+
+ /*
+ * Strictly, we don't need to maintain any state here but we need
+ * to return non-NULL to satisfy the API.
+ */
+ debug3("%s: preparing Darwin sandbox", __func__);
+ box = xcalloc(1, sizeof(*box));
+ box->child_pid = 0;
+
+ return box;
+}
+
+void
+ssh_sandbox_child(struct ssh_sandbox *box)
+{
+ char *errmsg;
+ struct rlimit rl_zero;
+
+ debug3("%s: starting Darwin sandbox", __func__);
+ if (sandbox_init(kSBXProfilePureComputation, SANDBOX_NAMED,
+ &errmsg) == -1)
+ fatal("%s: sandbox_init: %s", __func__, errmsg);
+
+ /*
+ * The kSBXProfilePureComputation still allows sockets, so
+ * we must disable these using rlimit.
+ */
+ rl_zero.rlim_cur = rl_zero.rlim_max = 0;
+ if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1)
+ fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s",
+ __func__, strerror(errno));
+ if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1)
+ fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s",
+ __func__, strerror(errno));
+ if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1)
+ fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s",
+ __func__, strerror(errno));
+}
+
+void
+ssh_sandbox_parent_finish(struct ssh_sandbox *box)
+{
+ free(box);
+ debug3("%s: finished", __func__);
+}
+
+void
+ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
+{
+ box->child_pid = child_pid;
+}
+
+#endif /* SANDBOX_DARWIN */