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Mike Palmiotto 05bdc03130 libselinux: use kernel status page by default
Commit bc2a8f418e ("libselinux: add selinux_status_* interfaces for
/selinux/status") introduced the sestatus mechanism, which allows for
mmap()'ing of the kernel status page as a replacement for avc_netlink.

The mechanism was initially intended for userspace object managers that
were calculating access decisions within their application and did not
rely on the libselinux AVC implementation. In order to properly make use
of sestatus within avc_has_perm(), the status mechanism needs to
properly set avc internals during status events; else, avc_enforcing is
never updated upon sestatus changes.

This commit gets rid of the default avc_netlink_open() in
avc_init_internal(), replacing it with selinux_status_open(). In the
event that the kernel status page cannot be mapped, the netlink fallback
will be used. By default, avc_has_perm_noaudit() and
selinux_check_access() will now attempt to read the kernel status page,
which removes a system call from two critical code paths.

Since the AVC thread create/stop callbacks were intended to avoid a
system call in the critical code path, they no longer need to be created
by default. In the event that the kernel status page is successfully
mapped, threads will not be created. Threads will still be
created/stopped for the sestatus fallback codepaths.

Userspace object managers that still need a netlink socket can call
avc_netlink_acquire_fd() to open and/or obtain one.

Update the manpage to reflect the new avc_netlink_acquire_fd()
functionality.

Signed-off-by: Mike Palmiotto <mike.palmiotto@crunchydata.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
2020-08-11 08:11:40 -04:00
.circleci CircleCI: run scan-build and publish its results automatically 2019-09-26 09:45:47 -04:00
checkpolicy libsepol,checkpolicy: optimize storage of filename transitions 2020-08-03 08:52:12 -04:00
dbus Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
gui Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
libselinux libselinux: use kernel status page by default 2020-08-11 08:11:40 -04:00
libsemanage Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
libsepol libsepol: implement POLICYDB_VERSION_COMP_FTRANS 2020-08-03 08:52:12 -04:00
mcstrans Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
policycoreutils Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
python python/audit2allow: add #include <limits.h> to sepolgen-ifgen-attr-helper.c 2020-07-21 08:14:43 +02:00
restorecond restorecond: Set X-GNOME-HiddenUnderSystemd=true in restorecond.desktop file 2020-07-21 08:14:57 +02:00
sandbox Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
scripts scripts/ci: license as MIT 2020-08-07 10:20:10 +02:00
secilc Update the cil docs to match the current behaviour. 2020-07-14 16:28:34 +02:00
semodule-utils Update VERSIONs and Python bindings version to 3.1 for release 2020-07-10 17:17:15 +02:00
.gitignore restorecond: Add gitignore 2016-11-16 11:20:05 -05:00
.travis.yml ci: run SELinux kernel test suite 2020-06-18 19:22:12 +02:00
CleanSpec.mk Add empty top level Android.mk / CleanSpec.mk files 2015-04-16 07:54:09 -04:00
CONTRIBUTING.md Fix many misspellings 2019-09-18 22:47:35 +02:00
lgtm.yml Add configuration file for lgtm.com 2019-09-18 08:24:11 -04:00
Makefile Makefile: always build with -fno-common 2020-01-27 10:51:23 -05:00
README.md README: start a section for documenting CFLAGS 2020-06-18 19:31:08 +02:00

SELinux Userspace

SELinux logo Build Status

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:

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