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Petr Lautrbach c7a3b93e31 libsemanage: Fall back to semanage_copy_dir when rename() fails
In some circumstances, like semanage-store being on overlayfs, rename()
could fail with EXDEV - Invalid cross-device link. This is due to the
fact that overlays doesn't support rename() if source and target are not
on the same layer, e.g. in containers built from several layers. Even
though it's not atomic operation, it's better to try to copy files from
src to dst on our own in this case. Next rebuild will probably not fail
as the new directories will be on the same layer.

Fixes: https://github.com/SELinuxProject/selinux/issues/343

Reproducer:

    $ cd selinux1

    $ cat Dockerfile
    FROM fedora:35
    RUN dnf install -y selinux-policy selinux-policy-targeted

    $ podman build -t localhost/selinux . --no-cache

    $ cd ../selinux2

    $ cat Dockerfile
    FROM localhost/selinux
    RUN semodule -B

    $ podman build -t localhost/selinux2 . --no-cache
    STEP 2/2: RUN semodule -B
    libsemanage.semanage_commit_sandbox: Error while renaming /var/lib/selinux/targeted/active to /var/lib/selinux/targeted/previous. (Invalid cross-device link).
    semodule:  Failed!
    Error: error building at STEP "RUN semodule -B": error while running runtime: exit status 1

With the fix:

    $ podman build -t localhost/selinux2 . --no-cache
    STEP 2/2: RUN semodule -B
    libsemanage.semanage_rename: Warning: rename(/var/lib/selinux/targeted/active, /var/lib/selinux/targeted/previous) failed: Invalid cross-device link, fall back to non-atomic semanage_copy_dir_flags()

    COMMIT localhost/selinux2
    --> d2cfcebc1a1
    Successfully tagged localhost/selinux2:latest
    d2cfcebc1a1b34f1c2cd661ac18292b0612c3e5fa71d6fa1441be244da91b1af

Reported-by: Joseph Marrero Corchado <jmarrero@redhat.com>
Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
Acked-by: Ondrej Mosnacek <omosnace@redhat.com>
2022-04-06 10:44:05 +02:00
.circleci Replace PCRE with PCRE2 build dependencies 2021-12-09 11:07:10 -05:00
.github/workflows ci: run the tests under ASan/UBsan on GHActions 2022-01-06 10:34:33 -05:00
checkpolicy libsepol: Populate and use policy name 2022-02-24 10:44:46 -05:00
dbus Update VERSIONs to 3.3 for release. 2021-10-21 16:31:23 +02:00
gui Update VERSIONs to 3.3 for release. 2021-10-21 16:31:23 +02:00
libselinux libselinux: Close leaked FILEs 2022-03-25 10:20:21 -04:00
libsemanage libsemanage: Fall back to semanage_copy_dir when rename() fails 2022-04-06 10:44:05 +02:00
libsepol libsepol: Validate conditional expressions 2022-03-30 13:43:31 -04:00
mcstrans mcstrans: port to new PCRE2 from end-of-life PCRE 2021-12-09 11:06:41 -05:00
policycoreutils policycoreutils/fixfiles: Use parallel relabeling 2022-03-11 10:03:55 -05:00
python semanage-fcontext.8: Drop extra )s after FILE_SPEC 2022-03-03 12:13:47 -05:00
restorecond Update VERSIONs to 3.3 for release. 2021-10-21 16:31:23 +02:00
sandbox sandbox: mark local functions static 2021-11-15 16:00:54 -05:00
scripts libsepol: add libfuzz based fuzzer for reading binary policies 2021-12-15 12:48:28 -05:00
secilc secilc: kernel policy language is infix 2022-03-30 13:31:04 -04:00
semodule-utils Update VERSIONs to 3.3 for release. 2021-10-21 16:31:23 +02:00
.gitignore restorecond: Add gitignore 2016-11-16 11:20:05 -05:00
.travis.yml travis: run only selinux-testsuite 2020-11-27 15:37:31 +01:00
CleanSpec.mk Add empty top level Android.mk / CleanSpec.mk files 2015-04-16 07:54:09 -04:00
CONTRIBUTING.md Replace PCRE with PCRE2 build dependencies 2021-12-09 11:07:10 -05:00
lgtm.yml Add configuration file for lgtm.com 2019-09-18 08:24:11 -04:00
Makefile Enable extra global compiler warnings 2021-11-15 16:00:54 -05:00
README.md Replace PCRE with PCRE2 build dependencies 2021-12-09 11:07:10 -05:00
SECURITY.md Add a file describing the security vulnerability handling process 2022-03-30 13:43:36 -04:00
VERSION Update VERSIONs to 3.3 for release. 2021-10-21 16:31:23 +02:00

SELinux Userspace

SELinux logo Run Tests Run SELinux testsuite in a virtual machine OSS-Fuzz Status CIFuzz 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 \
    pcre2-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 \
    libpcre2-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