340f0eb7f3
While there are some checks for invalid statements in an optional
block when resolving the AST, there are no checks when building the
AST.
OSS-Fuzz found the following policy which caused a null dereference
in cil_tree_get_next_path().
(blockinherit b3)
(sid SID)
(sidorder(SID))
(optional o
(ibpkeycon :(1 0)s)
(block b3
(filecon""block())
(filecon""block())))
The problem is that the blockinherit copies block b3 before
the optional block is disabled. When the optional is disabled,
block b3 is deleted along with everything else in the optional.
Later, when filecon statements with the same path are found an
error message is produced and in trying to find out where the block
was copied from, the reference to the deleted block is used. The
error handling code assumes (rightly) that if something was copied
from a block then that block should still exist.
It is clear that in-statements, blocks, and macros cannot be in an
optional, because that allows nodes to be copied from the optional
block to somewhere outside even though the optional could be disabled
later. When optionals are disabled the AST is reset and the
resolution is restarted at the point of resolving macro calls, so
anything resolved before macro calls will never be re-resolved.
This includes tunableifs, in-statements, blockinherits,
blockabstracts, and macro definitions. Tunable declarations also
cannot be in an optional block because they are needed to resolve
tunableifs. It should be fine to allow blockinherit statements in
an optional, because that is copying nodes from outside the optional
to the optional and if the optional is later disabled, everything
will be deleted anyway.
Check and quit with an error if a tunable declaration, in-statement,
block, blockabstract, or macro definition is found within an
optional when either building or resolving the AST.
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 | ||
| .travis.yml | ||
| CleanSpec.mk | ||
| CONTRIBUTING.md | ||
| lgtm.yml | ||
| Makefile | ||
| README.md | ||
| VERSION | ||
SELinux Userspace
Please submit all bug reports and patches to selinux@vger.kernel.org.
Subscribe by sending "subscribe selinux" in the body of an email to majordomo@vger.kernel.org.
Archive of this mailing list is available on 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 \
pcre-devel \
xmlto
# For Python and Ruby bindings
dnf install \
python3-devel \
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 \
libpcre3-dev \
pkgconf \
python3 \
python3-distutils \
systemd \
xmlto
# For Python and Ruby bindings
apt-get install --no-install-recommends --no-install-suggests \
python3-dev \
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 PYTHON_SETUP_ARGS=--install-layout=deb needs to be set when installing the python wrappers in order to create the correct python directory structure.
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).
In order to run these ones, instructions similar to the ones in section install of ./.travis.yml can be executed.
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