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Christian Göttsche 2331dcaf8e libsepol: enforce avtab item limit
Check the current item count does not exceed the maximum allowed to
avoid stack overflows.

    ==33660==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fa64b8fc070 at pc 0x0000005acba0 bp 0x7ffc1f0b2870 sp 0x7ffc1f0b2868
    READ of size 4 at 0x7fa64b8fc070 thread T0
        #0 0x5acb9f in avtab_read_item ./libsepol/src/avtab.c:507:18
        #1 0x5acec4 in avtab_read ./libsepol/src/avtab.c:611:8
        #2 0x576ae3 in policydb_read ./libsepol/src/policydb.c:4433:7
        #3 0x55a1fe in LLVMFuzzerTestOneInput ./libsepol/fuzz/binpolicy-fuzzer.c:24:6
        #4 0x45aed3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) fuzzer.o
        #5 0x446a12 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) fuzzer.o
        #6 0x44c93b in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) fuzzer.o
        #7 0x475dd2 in main (./out/binpolicy-fuzzer+0x475dd2)
        #8 0x7fa64cc867ec in __libc_start_main csu/../csu/libc-start.c:332:16
        #9 0x423689 in _start (./out/binpolicy-fuzzer+0x423689)

    Address 0x7fa64b8fc070 is located in stack of thread T0 at offset 112 in frame
        #0 0x5aabdf in avtab_read_item ./libsepol/src/avtab.c:437

      This frame has 6 object(s):
        [32, 33) 'buf8' (line 438)
        [48, 56) 'buf16' (line 439)
        [80, 112) 'buf32' (line 440) <== Memory access at offset 112 overflows this variable
        [144, 152) 'key' (line 441)
        [176, 192) 'datum' (line 442)
        [208, 244) 'xperms' (line 443)
    HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
          (longjmp and C++ exceptions *are* supported)
    SUMMARY: AddressSanitizer: stack-buffer-overflow ./libsepol/src/avtab.c:507:18 in avtab_read_item
    Shadow bytes around the buggy address:
      0x0ff5497177b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff5497177c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff5497177d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff5497177e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff5497177f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    =>0x0ff549717800: f1 f1 f1 f1 01 f2 00 f2 f2 f2 00 00 00 00[f2]f2
      0x0ff549717810: f2 f2 00 f2 f2 f2 00 00 f2 f2 00 00 00 00 04 f3
      0x0ff549717820: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff549717830: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff549717840: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0ff549717850: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    Shadow byte legend (one shadow byte represents 8 application bytes):
      Addressable:           00
      Partially addressable: 01 02 03 04 05 06 07
      Heap left redzone:       fa
      Freed heap region:       fd
      Stack left redzone:      f1
      Stack mid redzone:       f2
      Stack right redzone:     f3
      Stack after return:      f5
      Stack use after scope:   f8
      Global redzone:          f9
      Global init order:       f6
      Poisoned by user:        f7
      Container overflow:      fc
      Array cookie:            ac
      Intra object redzone:    bb
      ASan internal:           fe
      Left alloca redzone:     ca
      Right alloca redzone:    cb
    ==33660==ABORTING

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
2021-12-15 12:51:10 -05:00
.circleci Replace PCRE with PCRE2 build dependencies 2021-12-09 11:07:10 -05:00
.github/workflows cifuzz: use the default runtime of 600 seconds 2021-12-15 12:48:23 -05:00
checkpolicy checkpolicy: warn on bogus IP address or netmask in nodecon statement 2021-12-15 12:47:22 -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: use PCRE2 by default 2021-12-09 11:07:00 -05:00
libsemanage libsemanage: add extern prototype for legacy function 2021-11-15 16:00:54 -05:00
libsepol libsepol: enforce avtab item limit 2021-12-15 12:51:10 -05:00
mcstrans mcstrans: port to new PCRE2 from end-of-life PCRE 2021-12-09 11:06:41 -05:00
policycoreutils Modified Russian and English man pages to fix typo; REQUIREUSERS -> REQUIRESEUSERS 2021-11-29 18:51:19 +01:00
python python: mark local functions static 2021-11-15 16:00:54 -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/docs: Document the optional file type for genfscon rules 2021-12-09 10:46:26 -05:00
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
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