freebsd-dev/config/kernel-userns-capabilities.m4
Wolfgang Bumiller 0e85048f53 Take user namespaces into account in policy checks
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
2018-03-07 15:40:42 -08:00

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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
])