mirror of
git://anongit.mindrot.org/openssh.git
synced 2025-03-11 09:17:38 +00:00
- (djm) [Makefile.in configure.ac sandbox-seccomp-filter.c] Add sandbox
mode for Linux's new seccomp filter; patch from Will Drewry; feedback and ok dtucker@
This commit is contained in:
Damien Miller
parent
ce1ec9d4e2
commit
e0956e3834
@ -1,3 +1,8 @@
|
||||
20120404
|
||||
- (djm) [Makefile.in configure.ac sandbox-seccomp-filter.c] Add sandbox
|
||||
mode for Linux's new seccomp filter; patch from Will Drewry; feedback
|
||||
and ok dtucker@
|
||||
|
||||
20120330
|
||||
- (dtucker) [contrib/redhat/openssh.spec] Bug #1992: remove now-gone WARNING
|
||||
file from spec file. From crighter at nuclioss com.
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
# $Id: Makefile.in,v 1.325 2011/08/05 20:15:18 djm Exp $
|
||||
# $Id: Makefile.in,v 1.326 2012/04/04 01:27:57 djm Exp $
|
||||
|
||||
# uncomment if you run a non bourne compatable shell. Ie. csh
|
||||
#SHELL = @SH@
|
||||
@ -90,7 +90,8 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \
|
||||
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-darwin.o
|
||||
sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \
|
||||
sandbox-seccomp-filter.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
|
||||
|
||||
68
configure.ac
68
configure.ac
@ -1,4 +1,4 @@
|
||||
# $Id: configure.ac,v 1.487 2012/02/23 23:40:43 dtucker Exp $
|
||||
# $Id: configure.ac,v 1.488 2012/04/04 01:27:57 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: 1.487 $)
|
||||
AC_REVISION($Revision: 1.488 $)
|
||||
AC_CONFIG_SRCDIR([ssh.c])
|
||||
AC_LANG([C])
|
||||
|
||||
@ -116,6 +116,35 @@ AC_CHECK_DECL([RLIMIT_NPROC],
|
||||
#include <sys/types.h>
|
||||
#include <sys/resource.h>
|
||||
])
|
||||
AC_CHECK_DECL([PR_SET_NO_NEW_PRIVS], [have_linux_no_new_privs=1], , [
|
||||
#include <sys/types.h>
|
||||
#include <linux/prctl.h>
|
||||
])
|
||||
if test "x$have_linux_no_new_privs" = "x1" ; then
|
||||
AC_CHECK_DECL([SECCOMP_MODE_FILTER], [have_seccomp_filter=1], , [
|
||||
#include <sys/types.h>
|
||||
#include <linux/seccomp.h>
|
||||
])
|
||||
fi
|
||||
if test "x$have_seccomp_filter" = "x1" ; then
|
||||
AC_MSG_CHECKING([kernel for seccomp_filter support])
|
||||
AC_RUN_IFELSE([AC_LANG_PROGRAM([[
|
||||
#include <errno.h>
|
||||
#include <linux/seccomp.h>
|
||||
#include <stdlib.h>
|
||||
#include <sys/prctl.h>
|
||||
]],
|
||||
[[ errno = 0;
|
||||
prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, NULL, 0, 0);
|
||||
exit(errno == EFAULT ? 0 : 1); ]])],
|
||||
[ AC_MSG_RESULT([yes]) ], [
|
||||
AC_MSG_RESULT([no])
|
||||
# Disable seccomp filter as a target
|
||||
have_seccomp_filter=0
|
||||
],
|
||||
[ AC_MSG_RESULT([cross-compiling, assuming yes]) ]
|
||||
)
|
||||
fi
|
||||
|
||||
use_stack_protector=1
|
||||
AC_ARG_WITH([stackprotect],
|
||||
@ -657,6 +686,22 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16))
|
||||
AC_DEFINE([SSH_TUN_PREPEND_AF], [1],
|
||||
[Prepend the address family to IP tunnel traffic])
|
||||
fi
|
||||
AC_CHECK_HEADERS([linux/seccomp.h linux/filter.h linux/audit.h])
|
||||
AC_CHECK_FUNCS([prctl])
|
||||
have_seccomp_audit_arch=1
|
||||
case "$host" in
|
||||
x86_64-*)
|
||||
AC_DEFINE([SECCOMP_AUDIT_ARCH], [AUDIT_ARCH_X86_64],
|
||||
[Specify the system call convention in use])
|
||||
;;
|
||||
i*86-*)
|
||||
AC_DEFINE([SECCOMP_AUDIT_ARCH], [AUDIT_ARCH_I386],
|
||||
[Specify the system call convention in use])
|
||||
;;
|
||||
*)
|
||||
have_seccomp_audit_arch=0
|
||||
;;
|
||||
esac
|
||||
;;
|
||||
mips-sony-bsd|mips-sony-newsos4)
|
||||
AC_DEFINE([NEED_SETPGRP], [1], [Need setpgrp to acquire controlling tty])
|
||||
@ -2518,7 +2563,7 @@ 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, darwin, rlimit, systrace)],
|
||||
[ --with-sandbox=style Specify privilege separation sandbox (no, darwin, rlimit, systrace, seccomp_filter)],
|
||||
[
|
||||
if test "x$withval" = "xyes" ; then
|
||||
sandbox_arg=""
|
||||
@ -2541,6 +2586,23 @@ elif test "x$sandbox_arg" = "xdarwin" || \
|
||||
AC_MSG_ERROR([Darwin seatbelt sandbox requires sandbox.h and sandbox_init function])
|
||||
SANDBOX_STYLE="darwin"
|
||||
AC_DEFINE([SANDBOX_DARWIN], [1], [Sandbox using Darwin sandbox_init(3)])
|
||||
elif test "x$sandbox_arg" = "xseccomp_filter" || \
|
||||
( test -z "$sandbox_arg" && \
|
||||
test "x$have_seccomp_filter" == "x1" && \
|
||||
test "x$ac_cv_header_linux_audit_h" = "xyes" && \
|
||||
test "x$have_seccomp_audit_arch" = "x1" && \
|
||||
test "x$have_linux_no_new_privs" = "x1" && \
|
||||
test "x$ac_cv_func_prctl" = "xyes" ) ; then
|
||||
test "x$have_seccomp_audit_arch" != "x1" && \
|
||||
AC_MSG_ERROR([seccomp_filter sandbox not supported on $host])
|
||||
test "x$have_linux_no_new_privs" != "x1" && \
|
||||
AC_MSG_ERROR([seccomp_filter sandbox requires PR_SET_NO_NEW_PRIVS])
|
||||
test "x$have_seccomp_filter" != "x1" && \
|
||||
AC_MSG_ERROR([seccomp_filter sandbox requires seccomp headers])
|
||||
test "x$ac_cv_func_prctl" != "xyes" && \
|
||||
AC_MSG_ERROR([seccomp_filter sandbox requires prctl function])
|
||||
SANDBOX_STYLE="seccomp_filter"
|
||||
AC_DEFINE([SANDBOX_SECCOMP_FILTER], [1], [Sandbox using seccomp filter])
|
||||
elif test "x$sandbox_arg" = "xrlimit" || \
|
||||
( test -z "$sandbox_arg" && test "x$ac_cv_func_setrlimit" = "xyes" ) ; then
|
||||
test "x$ac_cv_func_setrlimit" != "xyes" && \
|
||||
|
||||
222
sandbox-seccomp-filter.c
Normal file
222
sandbox-seccomp-filter.c
Normal file
@ -0,0 +1,222 @@
|
||||
/*
|
||||
* Copyright (c) 2012 Will Drewry <wad@dataspill.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.
|
||||
*/
|
||||
|
||||
/*
|
||||
* Uncomment the SANDBOX_SECCOMP_FILTER_DEBUG macro below to help diagnose
|
||||
* filter breakage during development. *Do not* use this in production,
|
||||
* as it relies on making library calls that are unsafe in signal context.
|
||||
*
|
||||
* Instead, live systems the auditctl(8) may be used to monitor failures.
|
||||
* E.g.
|
||||
* auditctl -a task,always -F uid=<privsep uid>
|
||||
*/
|
||||
/* #define SANDBOX_SECCOMP_FILTER_DEBUG 1 */
|
||||
|
||||
#ifdef SANDBOX_SECCOMP_FILTER_DEBUG
|
||||
/* Use the kernel headers in case of an older toolchain. */
|
||||
# include <asm/siginfo.h>
|
||||
# define __have_siginfo_t 1
|
||||
# define __have_sigval_t 1
|
||||
# define __have_sigevent_t 1
|
||||
#endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
|
||||
|
||||
#include "includes.h"
|
||||
|
||||
#ifdef SANDBOX_SECCOMP_FILTER
|
||||
|
||||
#include <sys/types.h>
|
||||
#include <sys/resource.h>
|
||||
#include <sys/prctl.h>
|
||||
|
||||
#include <linux/audit.h>
|
||||
#include <linux/filter.h>
|
||||
#include <linux/seccomp.h>
|
||||
|
||||
#include <asm/unistd.h>
|
||||
|
||||
#include <errno.h>
|
||||
#include <signal.h>
|
||||
#include <stdarg.h>
|
||||
#include <stddef.h> /* for offsetof */
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <unistd.h>
|
||||
|
||||
#include "log.h"
|
||||
#include "ssh-sandbox.h"
|
||||
#include "xmalloc.h"
|
||||
|
||||
/* Linux seccomp_filter sandbox */
|
||||
#define SECCOMP_FILTER_FAIL SECCOMP_RET_KILL
|
||||
|
||||
/* Use a signal handler to emit violations when debugging */
|
||||
#ifdef SANDBOX_SECCOMP_FILTER_DEBUG
|
||||
# undef SECCOMP_FILTER_FAIL
|
||||
# define SECCOMP_FILTER_FAIL SECCOMP_RET_TRAP
|
||||
#endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
|
||||
|
||||
/* Simple helpers to avoid manual errors (but larger BPF programs). */
|
||||
#define SC_DENY(_nr, _errno) \
|
||||
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_ ## _nr, 0, 1), \
|
||||
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ERRNO|(_errno))
|
||||
#define SC_ALLOW(_nr) \
|
||||
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_ ## _nr, 0, 1), \
|
||||
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)
|
||||
|
||||
/* Syscall filtering set for preauth. */
|
||||
static const struct sock_filter preauth_insns[] = {
|
||||
/* Ensure the syscall arch convention is as expected. */
|
||||
BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
|
||||
offsetof(struct seccomp_data, arch)),
|
||||
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, SECCOMP_AUDIT_ARCH, 1, 0),
|
||||
BPF_STMT(BPF_RET+BPF_K, SECCOMP_FILTER_FAIL),
|
||||
/* Load the syscall number for checking. */
|
||||
BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
|
||||
offsetof(struct seccomp_data, nr)),
|
||||
SC_DENY(open, EACCES),
|
||||
SC_ALLOW(getpid),
|
||||
SC_ALLOW(gettimeofday),
|
||||
SC_ALLOW(time),
|
||||
SC_ALLOW(read),
|
||||
SC_ALLOW(write),
|
||||
SC_ALLOW(close),
|
||||
SC_ALLOW(brk),
|
||||
SC_ALLOW(poll),
|
||||
#ifdef __NR__newselect
|
||||
SC_ALLOW(_newselect),
|
||||
#else
|
||||
SC_ALLOW(select),
|
||||
#endif
|
||||
SC_ALLOW(madvise),
|
||||
SC_ALLOW(mmap),
|
||||
SC_ALLOW(munmap),
|
||||
SC_ALLOW(exit_group),
|
||||
#ifdef __NR_rt_sigprocmask
|
||||
SC_ALLOW(rt_sigprocmask),
|
||||
#else
|
||||
SC_ALLOW(sigprocmask),
|
||||
#endif
|
||||
BPF_STMT(BPF_RET+BPF_K, SECCOMP_FILTER_FAIL),
|
||||
};
|
||||
|
||||
static const struct sock_fprog preauth_program = {
|
||||
.len = (unsigned short)(sizeof(preauth_insns)/sizeof(preauth_insns[0])),
|
||||
.filter = (struct sock_filter *)preauth_insns,
|
||||
};
|
||||
|
||||
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 seccomp filter sandbox", __func__);
|
||||
box = xcalloc(1, sizeof(*box));
|
||||
box->child_pid = 0;
|
||||
|
||||
return box;
|
||||
}
|
||||
|
||||
#ifdef SANDBOX_SECCOMP_FILTER_DEBUG
|
||||
extern struct monitor *pmonitor;
|
||||
void mm_log_handler(LogLevel level, const char *msg, void *ctx);
|
||||
|
||||
static void
|
||||
ssh_sandbox_violation(int signum, siginfo_t *info, void *void_context)
|
||||
{
|
||||
char msg[256];
|
||||
|
||||
snprintf(msg, sizeof(msg),
|
||||
"%s: unexpected system call (arch:0x%x,syscall:%d @ %p)",
|
||||
__func__, info->si_arch, info->si_syscall, info->si_call_addr);
|
||||
mm_log_handler(SYSLOG_LEVEL_FATAL, msg, pmonitor);
|
||||
_exit(1);
|
||||
}
|
||||
|
||||
static void
|
||||
ssh_sandbox_child_debugging(void)
|
||||
{
|
||||
struct sigaction act;
|
||||
sigset_t mask;
|
||||
|
||||
debug3("%s: installing SIGSYS handler", __func__);
|
||||
memset(&act, 0, sizeof(act));
|
||||
sigemptyset(&mask);
|
||||
sigaddset(&mask, SIGSYS);
|
||||
|
||||
act.sa_sigaction = &ssh_sandbox_violation;
|
||||
act.sa_flags = SA_SIGINFO;
|
||||
if (sigaction(SIGSYS, &act, NULL) == -1)
|
||||
fatal("%s: sigaction(SIGSYS): %s", __func__, strerror(errno));
|
||||
if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1)
|
||||
fatal("%s: sigprocmask(SIGSYS): %s",
|
||||
__func__, strerror(errno));
|
||||
}
|
||||
#endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
|
||||
|
||||
void
|
||||
ssh_sandbox_child(struct ssh_sandbox *box)
|
||||
{
|
||||
struct rlimit rl_zero;
|
||||
|
||||
/* Set rlimits for completeness if possible. */
|
||||
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));
|
||||
|
||||
#ifdef SANDBOX_SECCOMP_FILTER_DEBUG
|
||||
ssh_sandbox_child_debugging();
|
||||
#endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
|
||||
|
||||
debug3("%s: setting PR_SET_NO_NEW_PRIVS", __func__);
|
||||
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
|
||||
fatal("%s: prctl(PR_SET_NO_NEW_PRIVS): %s",
|
||||
__func__, strerror(errno));
|
||||
debug3("%s: attaching seccomp filter program", __func__);
|
||||
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &preauth_program) == -1)
|
||||
fatal("%s: prctl(PR_SET_SECCOMP): %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_SECCOMP_FILTER */
|
||||
Loading…
Reference in New Issue
Block a user