- (djm) [Makefile.in configure.ac sandbox-capsicum.c sandbox-darwin.c]

[sandbox-null.c sandbox-rlimit.c sandbox-seccomp-filter.c]
   [sandbox-systrace.c ssh-sandbox.h sshd.c] Support preauth sandboxing
   using the Capsicum API introduced in FreeBSD 10. Patch by Dag-Erling
   Smorgrav, updated by Loganaden Velvindron @ AfriNIC; ok dtucker@

ChangeLog

@@ -23,6 +23,11 @@
    - dtucker@cvs.openbsd.org 2014/01/17 05:26:41
      [digest.c]
      remove unused includes.  ok djm@
+ - (djm) [Makefile.in configure.ac sandbox-capsicum.c sandbox-darwin.c]
+   [sandbox-null.c sandbox-rlimit.c sandbox-seccomp-filter.c]
+   [sandbox-systrace.c ssh-sandbox.h sshd.c] Support preauth sandboxing
+   using the Capsicum API introduced in FreeBSD 10. Patch by Dag-Erling
+   Smorgrav, updated by Loganaden Velvindron @ AfriNIC; ok dtucker@
 
 20140118
  - (djm) OpenBSD CVS Sync

Makefile.in

@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.349 2014/01/09 23:58:53 djm Exp $
+# $Id: Makefile.in,v 1.350 2014/01/17 05:47:04 djm Exp $
 
 # uncomment if you run a non bourne compatable shell. Ie. csh
 #SHELL = @SH@
@@ -96,7 +96,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \
 	sftp-server.o sftp-common.o \
 	roaming_common.o roaming_serv.o \
 	sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \
-	sandbox-seccomp-filter.o
+	sandbox-seccomp-filter.o sandbox-capsicum.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
@@ -472,4 +472,3 @@ package: $(CONFIGFILES) $(MANPAGES) $(TARGETS)
 	if [ "@MAKE_PACKAGE_SUPPORTED@" = yes ]; then \
 		sh buildpkg.sh; \
 	fi
-

configure.ac

@@ -1,4 +1,4 @@
-# $Id: configure.ac,v 1.549 2014/01/17 04:12:16 dtucker Exp $
+# $Id: configure.ac,v 1.550 2014/01/17 05:47:04 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: 1.549 $)
+AC_REVISION($Revision: 1.550 $)
 AC_CONFIG_SRCDIR([ssh.c])
 AC_LANG([C])
 
@@ -120,6 +120,10 @@ AC_CHECK_DECL([PR_SET_NO_NEW_PRIVS], [have_linux_no_new_privs=1], , [
 	#include <sys/types.h>
 	#include <linux/prctl.h>
 ])
+AC_CHECK_DECL([cap_enter], [have_cap_enter=1], , [
+	#include <sys/capability.h>
+])
+
 use_stack_protector=1
 use_toolchain_hardening=1
 AC_ARG_WITH([stackprotect],
@@ -2835,7 +2839,7 @@ fi
 # Decide which sandbox style to use
 sandbox_arg=""
 AC_ARG_WITH([sandbox],
-	[  --with-sandbox=style    Specify privilege separation sandbox (no, darwin, rlimit, systrace, seccomp_filter)],
+	[  --with-sandbox=style    Specify privilege separation sandbox (no, darwin, rlimit, systrace, seccomp_filter, capsicum)],
 	[
 		if test "x$withval" = "xyes" ; then
 			sandbox_arg=""
@@ -2974,6 +2978,13 @@ elif test "x$sandbox_arg" = "xrlimit" || \
 		AC_MSG_ERROR([rlimit sandbox requires select to work with rlimit])
 	SANDBOX_STYLE="rlimit"
 	AC_DEFINE([SANDBOX_RLIMIT], [1], [Sandbox using setrlimit(2)])
+elif test "x$sandbox_arg" = "xcapsicum" || \
+     ( test -z "$sandbox_arg" && \
+       test "x$have_cap_enter" = "x1") ; then
+       test "x$have_cap_enter" != "x1" && \
+		AC_MSG_ERROR([capsicum sandbox requires cap_enter function])
+       SANDBOX_STYLE="capsicum"
+       AC_DEFINE([SANDBOX_CAPSICUM], [1], [Sandbox using capsicum])
 elif test -z "$sandbox_arg" || test "x$sandbox_arg" = "xno" || \
      test "x$sandbox_arg" = "xnone" || test "x$sandbox_arg" = "xnull" ; then
 	SANDBOX_STYLE="none"

sandbox-capsicum.c

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2011 Dag-Erling Smorgrav
+ *
+ * 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_CAPSICUM
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "monitor.h"
+#include "ssh-sandbox.h"
+#include "xmalloc.h"
+
+/*
+ * Capsicum sandbox that sets zero nfiles, nprocs and filesize rlimits,
+ * limits rights on stdout, stdin, stderr, monitor and switches to
+ * capability mode.
+ */
+
+struct ssh_sandbox {
+	struct monitor *monitor;
+	pid_t child_pid;
+};
+
+struct ssh_sandbox *
+ssh_sandbox_init(struct monitor *monitor)
+{
+	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 capsicum sandbox", __func__);
+	box = xcalloc(1, sizeof(*box));
+	box->monitor = monitor;
+	box->child_pid = 0;
+
+	return box;
+}
+
+void
+ssh_sandbox_child(struct ssh_sandbox *box)
+{
+	struct rlimit rl_zero;
+	cap_rights_t rights;
+
+	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));
+
+	cap_rights_init(&rights);
+
+	if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS)
+		fatal("can't limit stdin: %m");
+	if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS)
+		fatal("can't limit stdin: %m");
+	if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS)
+		fatal("can't limit stdin: %m");
+
+	cap_rights_init(&rights, CAP_READ, CAP_WRITE);
+	if (cap_rights_limit(box->monitor->m_recvfd, &rights) == -1)
+		fatal("%s: failed to limit the network socket", __func__);
+	cap_rights_init(&rights, CAP_WRITE);
+	if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) == -1)
+		fatal("%s: failed to limit the logging socket", __func__);
+	if (cap_enter() != 0 && errno != ENOSYS)
+		fatal("%s: failed to enter capability mode", __func__);
+
+}
+
+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_CAPSICUM */

sandbox-darwin.c

@@ -40,7 +40,7 @@ struct ssh_sandbox {
 };
 
 struct ssh_sandbox *
-ssh_sandbox_init(void)
+ssh_sandbox_init(struct monitor *monitor)
 {
 	struct ssh_sandbox *box;
 

sandbox-null.c

@@ -39,7 +39,7 @@ struct ssh_sandbox {
 };
 
 struct ssh_sandbox *
-ssh_sandbox_init(void)
+ssh_sandbox_init(struct monitor *monitor)
 {
 	struct ssh_sandbox *box;
 

sandbox-rlimit.c

@@ -42,7 +42,7 @@ struct ssh_sandbox {
 };
 
 struct ssh_sandbox *
-ssh_sandbox_init(void)
+ssh_sandbox_init(struct monitor *monitor)
 {
 	struct ssh_sandbox *box;
 

sandbox-seccomp-filter.c

@@ -132,7 +132,7 @@ struct ssh_sandbox {
 };
 
 struct ssh_sandbox *
-ssh_sandbox_init(void)
+ssh_sandbox_init(struct monitor *monitor)
 {
 	struct ssh_sandbox *box;
 

sandbox-systrace.c

@@ -78,7 +78,7 @@ struct ssh_sandbox {
 };
 
 struct ssh_sandbox *
-ssh_sandbox_init(void)
+ssh_sandbox_init(struct monitor *monitor)
 {
 	struct ssh_sandbox *box;
 

ssh-sandbox.h

@@ -15,9 +15,10 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+struct monitor;
 struct ssh_sandbox;
 
-struct ssh_sandbox *ssh_sandbox_init(void);
+struct ssh_sandbox *ssh_sandbox_init(struct monitor *);
 void ssh_sandbox_child(struct ssh_sandbox *);
 void ssh_sandbox_parent_finish(struct ssh_sandbox *);
 void ssh_sandbox_parent_preauth(struct ssh_sandbox *, pid_t);

sshd.c

@@ -660,7 +660,7 @@ privsep_preauth(Authctxt *authctxt)
 	pmonitor->m_pkex = &xxx_kex;
 
 	if (use_privsep == PRIVSEP_ON)
-		box = ssh_sandbox_init();
+		box = ssh_sandbox_init(pmonitor);
 	pid = fork();
 	if (pid == -1) {
 		fatal("fork of unprivileged child failed");