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Take user namespaces into account in policy checks

Browse Source 
Change file related checks to use user namespaces and make
sure involved uids/gids are mappable in the current
namespace.

Note that checks without file ownership information will
still not take user namespaces into account, as some of
these should be handled via 'zfs allow' (otherwise root in a
user namespace could issue commands such as `zpool export`).

This also adds an initial user namespace regression test
for the setgid bit loss, with a user_ns_exec helper usable
in further tests.

Additionally, configure checks for the required user
namespace related features are added for:
  * ns_capable
  * kuid/kgid_has_mapping()
  * user_ns in cred_t

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
Closes #6800 
Closes #7270
This commit is contained in:
Wolfgang Bumiller 2018-03-08 00:40:42 +01:00 committed by Brian Behlendorf
parent 434a3375ce
commit 0e85048f53
17 changed files with 521 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
config/kernel-userns-capabilities.m4 Normal file
View File

@ -0,0 +1,67 @@
dnl #
dnl # 2.6.38 API change
dnl # ns_capable() was introduced
dnl #
AC_DEFUN([ZFS_AC_KERNEL_NS_CAPABLE], [
AC_MSG_CHECKING([whether ns_capable exists])
ZFS_LINUX_TRY_COMPILE([
#include <linux/capability.h>
],[
ns_capable((struct user_namespace *)NULL, CAP_SYS_ADMIN);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_NS_CAPABLE, 1,
[ns_capable exists])
],[
AC_MSG_RESULT(no)
])
])
dnl #
dnl # 2.6.39 API change
dnl # struct user_namespace was added to struct cred_t as
dnl # cred->user_ns member
dnl # Note that current_user_ns() was added in 2.6.28.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_CRED_USER_NS], [
AC_MSG_CHECKING([whether cred_t->user_ns exists])
ZFS_LINUX_TRY_COMPILE([
#include <linux/cred.h>
],[
struct cred cr;
cr.user_ns = (struct user_namespace *)NULL;
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_CRED_USER_NS, 1,
[cred_t->user_ns exists])
],[
AC_MSG_RESULT(no)
])
])
dnl #
dnl # 3.4 API change
dnl # kuid_has_mapping() and kgid_has_mapping() were added to distinguish
dnl # between internal kernel uids/gids and user namespace uids/gids.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_KUID_HAS_MAPPING], [
AC_MSG_CHECKING([whether kuid_has_mapping/kgid_has_mapping exist])
ZFS_LINUX_TRY_COMPILE([
#include <linux/uidgid.h>
],[
kuid_has_mapping((struct user_namespace *)NULL, KUIDT_INIT(0));
kgid_has_mapping((struct user_namespace *)NULL, KGIDT_INIT(0));
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_KUID_HAS_MAPPING, 1,
[kuid_has_mapping/kgid_has_mapping exist])
],[
AC_MSG_RESULT(no)
])
])
AC_DEFUN([ZFS_AC_KERNEL_USERNS_CAPABILITIES], [
ZFS_AC_KERNEL_NS_CAPABLE
ZFS_AC_KERNEL_CRED_USER_NS
ZFS_AC_KERNEL_KUID_HAS_MAPPING
])

1
config/kernel.m4
View File

@ -126,6 +126,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
ZFS_AC_KERNEL_CURRENT_TIME
ZFS_AC_KERNEL_GLOBAL_PAGE_STATE
ZFS_AC_KERNEL_ACL_HAS_REFCOUNT
ZFS_AC_KERNEL_USERNS_CAPABILITIES
AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
KERNEL_MAKE="$KERNEL_MAKE O=$LINUX_OBJ"

2
configure.ac
View File

@ -153,6 +153,7 @@ AC_CONFIG_FILES([
tests/zfs-tests/callbacks/Makefile
tests/zfs-tests/cmd/Makefile
tests/zfs-tests/cmd/chg_usr_exec/Makefile
tests/zfs-tests/cmd/user_ns_exec/Makefile
tests/zfs-tests/cmd/devname2devid/Makefile
tests/zfs-tests/cmd/dir_rd_update/Makefile
tests/zfs-tests/cmd/file_check/Makefile
@ -299,6 +300,7 @@ AC_CONFIG_FILES([
tests/zfs-tests/tests/functional/threadsappend/Makefile
tests/zfs-tests/tests/functional/tmpfile/Makefile
tests/zfs-tests/tests/functional/truncate/Makefile
tests/zfs-tests/tests/functional/user_namespace/Makefile
tests/zfs-tests/tests/functional/userquota/Makefile
tests/zfs-tests/tests/functional/upgrade/Makefile
tests/zfs-tests/tests/functional/vdev_zaps/Makefile

66
module/zfs/policy.c
View File

@ -42,19 +42,47 @@
* all other cases this function must fail and return the passed err.
*/
static int
priv_policy(const cred_t *cr, int capability, boolean_t all, int err)
priv_policy_ns(const cred_t *cr, int capability, boolean_t all, int err,
struct user_namespace *ns)
{
ASSERT3S(all, ==, B_FALSE);
if (cr != CRED() && (cr != kcred))
return (err);
#if defined(CONFIG_USER_NS) && defined(HAVE_NS_CAPABLE)
if (!(ns ? ns_capable(ns, capability) : capable(capability)))
#else
if (!capable(capability))
#endif
return (err);
return (0);
}
static int
priv_policy(const cred_t *cr, int capability, boolean_t all, int err)
{
return (priv_policy_ns(cr, capability, all, err, NULL));
}
static int
priv_policy_user(const cred_t *cr, int capability, boolean_t all, int err)
{
/*
* All priv_policy_user checks are preceeded by kuid/kgid_has_mapping()
* checks. If we cannot do them, we shouldn't be using ns_capable()
* since we don't know whether the affected files are valid in our
* namespace. Note that kuid_has_mapping() came after cred->user_ns, so
* we shouldn't need to re-check for HAVE_CRED_USER_NS
*/
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
return (priv_policy_ns(cr, capability, all, err, cr->user_ns));
#else
return (priv_policy_ns(cr, capability, all, err, NULL));
#endif
}
/*
* Checks for operations that are either client-only or are used by
* both clients and servers.
@ -102,10 +130,15 @@ secpolicy_vnode_any_access(const cred_t *cr, struct inode *ip, uid_t owner)
if (zpl_inode_owner_or_capable(ip))
return (0);
if (priv_policy(cr, CAP_DAC_OVERRIDE, B_FALSE, EPERM) == 0)
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
return (EPERM);
#endif
if (priv_policy_user(cr, CAP_DAC_OVERRIDE, B_FALSE, EPERM) == 0)
return (0);
if (priv_policy(cr, CAP_DAC_READ_SEARCH, B_FALSE, EPERM) == 0)
if (priv_policy_user(cr, CAP_DAC_READ_SEARCH, B_FALSE, EPERM) == 0)
return (0);
return (EPERM);
@ -120,7 +153,12 @@ secpolicy_vnode_chown(const cred_t *cr, uid_t owner)
if (crgetfsuid(cr) == owner)
return (0);
return (priv_policy(cr, CAP_FOWNER, B_FALSE, EPERM));
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
return (EPERM);
#endif
return (priv_policy_user(cr, CAP_FOWNER, B_FALSE, EPERM));
}
/*
@ -152,7 +190,12 @@ secpolicy_vnode_setdac(const cred_t *cr, uid_t owner)
if (crgetfsuid(cr) == owner)
return (0);
return (priv_policy(cr, CAP_FOWNER, B_FALSE, EPERM));
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
return (EPERM);
#endif
return (priv_policy_user(cr, CAP_FOWNER, B_FALSE, EPERM));
}
/*
@ -175,8 +218,12 @@ secpolicy_vnode_setid_retain(const cred_t *cr, boolean_t issuidroot)
int
secpolicy_vnode_setids_setgids(const cred_t *cr, gid_t gid)
{
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
if (!kgid_has_mapping(cr->user_ns, SGID_TO_KGID(gid)))
return (EPERM);
#endif
if (crgetfsgid(cr) != gid && !groupmember(gid, cr))
return (priv_policy(cr, CAP_FSETID, B_FALSE, EPERM));
return (priv_policy_user(cr, CAP_FSETID, B_FALSE, EPERM));
return (0);
}
@ -222,7 +269,12 @@ secpolicy_vnode_setid_modify(const cred_t *cr, uid_t owner)
if (crgetfsuid(cr) == owner)
return (0);
return (priv_policy(cr, CAP_FSETID, B_FALSE, EPERM));
#if defined(CONFIG_USER_NS) && defined(HAVE_KUID_HAS_MAPPING)
if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner)))
return (EPERM);
#endif
return (priv_policy_user(cr, CAP_FSETID, B_FALSE, EPERM));
}
/*

4
tests/runfiles/linux.run
View File

@ -743,6 +743,10 @@ tags = ['functional', 'truncate']
tests = ['upgrade_userobj_001_pos', 'upgrade_projectquota_001_pos']
tags = ['functional', 'upgrade']
[tests/functional/user_namespace]
tests = ['user_namespace_001']
tags = ['functional', 'user_namespace']
[tests/functional/userquota]
tests = [
'userquota_001_pos', 'userquota_002_pos', 'userquota_003_pos',

1
tests/zfs-tests/cmd/Makefile.am
View File

@ -2,6 +2,7 @@ EXTRA_DIST = file_common.h
SUBDIRS = \
chg_usr_exec \
user_ns_exec \
devname2devid \
dir_rd_update \
file_check \

1
tests/zfs-tests/cmd/user_ns_exec/.gitignore vendored Normal file
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@ -0,0 +1 @@
/user_ns_exec

6
tests/zfs-tests/cmd/user_ns_exec/Makefile.am Normal file
View File

@ -0,0 +1,6 @@
include $(top_srcdir)/config/Rules.am
pkgexecdir = $(datadir)/@PACKAGE@/zfs-tests/bin
pkgexec_PROGRAMS = user_ns_exec
user_ns_exec_SOURCES = user_ns_exec.c

179
tests/zfs-tests/cmd/user_ns_exec/user_ns_exec.c Normal file
View File

@ -0,0 +1,179 @@
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <sched.h>
#define EXECSHELL "/bin/sh"
#define UIDMAP "0 100000 65536"
static int
child_main(int argc, char *argv[], int sync_pipe)
{
char sync_buf;
char cmds[BUFSIZ] = { 0 };
char sep[] = " ";
int i, len;
if (unshare(CLONE_NEWUSER | CLONE_NEWNS) != 0) {
perror("unshare");
return (1);
}
/* tell parent we entered the new namespace */
if (write(sync_pipe, "1", 1) != 1) {
perror("write");
return (1);
}
/* wait for parent to setup the uid mapping */
if (read(sync_pipe, &sync_buf, 1) != 1) {
(void) fprintf(stderr, "user namespace setup failed\n");
return (1);
}
close(sync_pipe);
if (setuid(0) != 0) {
perror("setuid");
return (1);
}
if (setgid(0) != 0) {
perror("setgid");
return (1);
}
len = 0;
for (i = 1; i < argc; i++) {
(void) snprintf(cmds+len, sizeof (cmds)-len,
"%s%s", argv[i], sep);
len += strlen(argv[i]) + strlen(sep);
}
if (execl(EXECSHELL, "sh", "-c", cmds, (char *)NULL) != 0) {
perror("execl: " EXECSHELL);
return (1);
}
return (0);
}
static int
set_idmap(pid_t pid, const char *file)
{
int result = 0;
int mapfd;
char path[PATH_MAX];
(void) snprintf(path, sizeof (path), "/proc/%d/%s", (int)pid, file);
mapfd = open(path, O_WRONLY);
if (mapfd < 0) {
result = errno;
perror("open");
return (errno);
}
if (write(mapfd, UIDMAP, sizeof (UIDMAP)-1) != sizeof (UIDMAP)-1) {
perror("write");
result = (errno);
}
close(mapfd);
return (result);
}
int
main(int argc, char *argv[])
{
char sync_buf;
int result, wstatus;
int syncfd[2];
pid_t child;
if (argc < 2 || strlen(argv[1]) == 0) {
(void) printf("\tUsage: %s <commands> ...\n", argv[0]);
return (1);
}
if (socketpair(AF_UNIX, SOCK_STREAM, 0, syncfd) != 0) {
perror("socketpair");
return (1);
}
child = fork();
if (child == (pid_t)-1) {
perror("fork");
return (1);
}
if (child == 0) {
close(syncfd[0]);
return (child_main(argc, argv, syncfd[1]));
}
close(syncfd[1]);
result = 0;
/* wait for the child to have unshared its namespaces */
if (read(syncfd[0], &sync_buf, 1) != 1) {
perror("read");
kill(child, SIGKILL);
result = 1;
goto reap;
}
/* write uid mapping */
if (set_idmap(child, "uid_map") != 0 ||
set_idmap(child, "gid_map") != 0) {
result = 1;
kill(child, SIGKILL);
goto reap;
}
/* tell the child to proceed */
if (write(syncfd[0], "1", 1) != 1) {
perror("write");
kill(child, SIGKILL);
result = 1;
goto reap;
}
close(syncfd[0]);
reap:
while (waitpid(child, &wstatus, 0) != child)
kill(child, SIGKILL);
if (result == 0)
result = WEXITSTATUS(wstatus);
return (result);
}

1
tests/zfs-tests/include/commands.cfg
View File

@ -171,4 +171,5 @@ export ZFSTEST_FILES='chg_usr_exec
rename_dir
rm_lnkcnt_zero_file
threadsappend
user_ns_exec
xattrtest'

1
tests/zfs-tests/tests/functional/Makefile.am
View File

@ -63,6 +63,7 @@ SUBDIRS = \
tmpfile \
truncate \
upgrade \
user_namespace \
userquota \
vdev_zaps \
write_dirs \

7
tests/zfs-tests/tests/functional/user_namespace/Makefile.am Normal file
View File

@ -0,0 +1,7 @@
pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/user_namespace
dist_pkgdata_SCRIPTS = \
setup.ksh \
cleanup.ksh \
user_namespace_common.kshlib \
user_namespace.cfg \
user_namespace_001.ksh

25
tests/zfs-tests/tests/functional/user_namespace/cleanup.ksh Executable file
View File

@ -0,0 +1,25 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
. $STF_SUITE/include/libtest.shlib
default_cleanup

32
tests/zfs-tests/tests/functional/user_namespace/setup.ksh Executable file
View File

@ -0,0 +1,32 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
. $STF_SUITE/include/libtest.shlib
if ! [ -f /proc/self/uid_map ]; then
log_unsupported "The kernel doesn't support user namespaces."
fi
verify_runnable "both"
DISK=${DISKS%% *}
default_setup $DISK

23
tests/zfs-tests/tests/functional/user_namespace/user_namespace.cfg Normal file
View File

@ -0,0 +1,23 @@
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
export ROOT_UID=100000
export OTHER_UID=101000

89
tests/zfs-tests/tests/functional/user_namespace/user_namespace_001.ksh Executable file
View File

@ -0,0 +1,89 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
. $STF_SUITE/tests/functional/user_namespace/user_namespace_common.kshlib
#
#
# DESCRIPTION:
# Regression test for secpolicy_vnode_setids_setgids
#
#
# STRATEGY:
# 1. Create files with various owners.
# 2. Try to set setgid bit.
#
verify_runnable "both"
# rroot: real root,
# uroot: root within user namespace
# uother: other user within user namespace
set -A files rroot_rroot uroot_uroot uroot_other uother_uroot uother_uother
function cleanup
{
for i in ${files[*]}; do
log_must rm -f $TESTDIR/$i
done
}
log_onexit cleanup
log_assert "Check root in user namespaces"
TOUCH=$(readlink -e $(which touch))
CHMOD=$(readlink -e $(which chmod))
for i in ${files[*]}; do
log_must $TOUCH $TESTDIR/$i
log_must $CHMOD 0644 $TESTDIR/$i
done
log_must chown 0:0 $TESTDIR/rroot_rroot
log_must chown $ROOT_UID:$ROOT_UID $TESTDIR/uroot_uroot
log_must chown $ROOT_UID:$OTHER_UID $TESTDIR/uroot_other
log_must chown $OTHER_UID:$ROOT_UID $TESTDIR/uother_uroot
log_must chown $OTHER_UID:$OTHER_UID $TESTDIR/uother_uother
log_mustnot user_ns_exec $CHMOD 02755 $TESTDIR/rroot_rroot
log_mustnot test -g $TESTDIR/rroot_rroot
log_must user_ns_exec $CHMOD 02755 $TESTDIR/uroot_uroot
log_must test -g $TESTDIR/uroot_uroot
log_must user_ns_exec $CHMOD 02755 $TESTDIR/uroot_other
log_must test -g $TESTDIR/uroot_other
log_must user_ns_exec $CHMOD 02755 $TESTDIR/uother_uroot
log_must test -g $TESTDIR/uother_uroot
log_must user_ns_exec $CHMOD 02755 $TESTDIR/uother_uother
log_must test -g $TESTDIR/uother_uother
log_mustnot user_ns_exec $TOUCH $TESTDIR/rroot_rroot
log_must $CHMOD 0666 $TESTDIR/rroot_rroot
for i in ${files[*]}; do
log_must user_ns_exec $TOUCH $TESTDIR/$i
done
log_pass "Check root in user namespaces"

23
tests/zfs-tests/tests/functional/user_namespace/user_namespace_common.kshlib Normal file
View File

@ -0,0 +1,23 @@
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
. $STF_SUITE/include/libtest.shlib
. $STF_SUITE/tests/functional/user_namespace/user_namespace.cfg