6f2b689f63
When a user is created in an optional block, a user datum is added
to both the avrule_decl's symtab and the policydb's symtab, but
the semantic MLS information is only added to the avrule_decl's
user datum. This causes an error to occur during policy expansion
when user_copy_callback() is called. If this error did not occur
then the policydb's user datum would be written without any MLS
info and the policy would fail validation when read later.
When creating a user datum, search for a user datum with the same
key in the policydb's symtab. If that datum has no MLS information,
then copy the MLS information from the avrule_decl's datum. If it
does, then compare the default level, low level, and high level
sensitivities and give an error if they do not match. There is not
enough information to expand the categories for the high and low
levels, so merge the semantic categories. If the two category sets
are not equal an error will occur during the expansion phase.
A minimum policy to demonstrate the bug:
class CLASS1
sid kernel
class CLASS1 { PERM1 }
sensitivity SENS1;
dominance { SENS1 }
level SENS1;
mlsconstrain CLASS1 { PERM1 } ((h1 dom h2) and (l1 domby h1));
type TYPE1;
allow TYPE1 self : CLASS1 PERM1;
role ROLE1;
role ROLE1 types TYPE1;
optional {
require {
role ROLE1;
}
user USER2 roles ROLE1 level SENS1 range SENS1;
}
user USER1 roles ROLE1 level SENS1 range SENS1;
sid kernel USER1:ROLE1:TYPE1:SENS1
Signed-off-by: James Carter <jwcart2@gmail.com>
|
||
|---|---|---|
| .circleci | ||
| .github/workflows | ||
| checkpolicy | ||
| dbus | ||
| gui | ||
| libselinux | ||
| libsemanage | ||
| libsepol | ||
| mcstrans | ||
| policycoreutils | ||
| python | ||
| restorecond | ||
| sandbox | ||
| scripts | ||
| secilc | ||
| semodule-utils | ||
| .gitignore | ||
| CONTRIBUTING.md | ||
| CleanSpec.mk | ||
| LICENSE | ||
| Makefile | ||
| README.md | ||
| SECURITY.md | ||
| VERSION | ||
README.md
SELinux Userspace
SELinux is a flexible Mandatory Access Control (MAC) system built into the Linux Kernel. SELinux provides administrators with a comprehensive access control mechanism that enables greater access granularity over the existing Linux Discretionary Access Controls (DAC) and is present in many major Linux distributions. This repository contains the sources for the SELinux utilities and system libraries which allow for the configuration and management of an SELinux-based system.
Please submit all bug reports and patches to the selinux@vger.kernel.org mailing list. You can subscribe by sending "subscribe selinux" in the body of an email to majordomo@vger.kernel.org. Archives of the mailing list are available at https://lore.kernel.org/selinux.
Installation
SELinux libraries and tools are packaged in several Linux distributions:
- Alpine Linux (https://pkgs.alpinelinux.org/package/edge/testing/x86/policycoreutils)
- Arch Linux User Repository (https://aur.archlinux.org/packages/policycoreutils/)
- Buildroot (https://git.buildroot.net/buildroot/tree/package/policycoreutils)
- Debian and Ubuntu (https://packages.debian.org/sid/policycoreutils)
- Gentoo (https://packages.gentoo.org/packages/sys-apps/policycoreutils)
- RHEL and Fedora (https://src.fedoraproject.org/rpms/policycoreutils)
- Yocto Project (http://git.yoctoproject.org/cgit/cgit.cgi/meta-selinux/tree/recipes-security/selinux)
- and many more (https://repology.org/project/policycoreutils/versions)
Building and testing
Build dependencies on Fedora:
# For C libraries and programs
dnf install \
audit-libs-devel \
bison \
bzip2-devel \
CUnit-devel \
diffutils \
flex \
gcc \
gettext \
glib2-devel \
make \
libcap-devel \
libcap-ng-devel \
pam-devel \
pcre2-devel \
xmlto
# For Python and Ruby bindings
dnf install \
python3-devel \
python3-pip \
python3-setuptools \
python3-wheel \
ruby-devel \
swig
Build dependencies on Debian:
# For C libraries and programs
apt-get install --no-install-recommends --no-install-suggests \
bison \
flex \
gawk \
gcc \
gettext \
make \
libaudit-dev \
libbz2-dev \
libcap-dev \
libcap-ng-dev \
libcunit1-dev \
libglib2.0-dev \
libpcre2-dev \
pkgconf \
python3 \
systemd \
xmlto
# For Python and Ruby bindings
apt-get install --no-install-recommends --no-install-suggests \
python3-dev \
python3-pip \
python3-setuptools \
python3-wheel \
ruby-dev \
swig
To build and install everything under a private directory, run:
make clean distclean
make DESTDIR=~/obj install install-rubywrap install-pywrap
On Debian the environment variable DEB_PYTHON_INSTALL_LAYOUT needs to be set
to deb when installing the Python wrappers in order to create the correct
Python directory structure.
On Debian systems older than bookworm set
PYTHON_SETUP_ARGS='--install-option "--install-layout=deb"' instead.
To run tests with the built libraries and programs, several paths (relative to $DESTDIR) need to be added to variables $LD_LIBRARY_PATH, $PATH and $PYTHONPATH.
This can be done using ./scripts/env_use_destdir:
DESTDIR=~/obj ./scripts/env_use_destdir make test
Some tests require the reference policy to be installed (for example in python/sepolgen).
To install as the default system libraries and binaries (overwriting any previously installed ones - dangerous!), on x86_64, run:
make LIBDIR=/usr/lib64 SHLIBDIR=/lib64 install install-pywrap relabel
or on x86 (32-bit), run:
make install install-pywrap relabel
This may render your system unusable if the upstream SELinux userspace lacks library functions or other dependencies relied upon by your distribution. If it breaks, you get to keep both pieces.
Setting CFLAGS
Setting CFLAGS during the make process will cause the omission of many defaults. While the project strives to provide a reasonable set of default flags, custom CFLAGS could break the build, or have other undesired changes on the build output. Thus, be very careful when setting CFLAGS. CFLAGS that are encouraged to be set when overriding are:
- -fno-semantic-interposition for gcc or compilers that do not do this. clang does this by default. clang-10 and up will support passing this flag, but ignore it. Previous clang versions fail.
macOS
To install libsepol on macOS (mainly for policy analysis):
cd libsepol; make PREFIX=/usr/local install
This requires GNU coreutils:
brew install coreutils