Nikolay Kolev reported a build issue on Mac OS X 10.9 (Mavericks) where fwknop
copies of strlcpy() and strlcat() functions were conflicting with those that ship
with OS X 10.9.
The solution was to add a configure.ac check for strlcat() and strlcpy() and
wrap "#if !HAVE_..." checks around those functions.
A portion of the build errors looked like this:
/Applications/Xcode.app/Contents/Developer/usr/bin/make all-recursive
Making all in lib
/bin/sh ../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I.. -I ../common -g -O2 -Wall -Wformat -Wformat-security -fstack-protector-all -fstack-protector -fPIE -D_FORTIFY_SOURCE=2 -MT base64.lo -MD -MP -MF .deps/base64.Tpo -c -o base64.lo base64.c
libtool: compile: gcc -DHAVE_CONFIG_H -I. -I.. -I ../common -g -O2 -Wall -Wformat -Wformat-security -fstack-protector-all -fstack-protector -D_FORTIFY_SOURCE=2 -MT base64.lo -MD -MP -MF .deps/base64.Tpo -c base64.c -fno-common -DPIC -o .libs/base64.o
In file included from base64.c:34:
In file included from ./fko_common.h:149:
./fko_util.h:56:9: error: expected parameter declarator
size_t strlcat(char *dst, const char *src, size_t siz);
^
/usr/include/secure/_string.h:111:44: note: expanded from macro 'strlcat'
__builtin___strlcat_chk (dest, src, len, __darwin_obsz (dest))
^
/usr/include/secure/_common.h:39:62: note: expanded from macro '__darwin_obsz'
#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)
^
This commit bumps the fwknop version to 2.5 and sets the libfko version to 2.0 to
signal incompatibility with older libfko versions. Backwards compatibility is
maintained in SPA packet construction, but function prototypes in libfko-2.0 are
no longer compatible with older versions.
This commit also returns non-zero exit status under 'fwknopd --status' if there
is no existing fwknopd process. This is better than always exiting with a zero
status regardless of whether fwknopd is already running or not, and adds a level
of scriptability to --status usage. This change was suggested by George Herlin.
Added --disable-gpg to the autoconf ./configure script
via configure.ac. This makes it easy to not have fwknop/fwknopd
link against libgpgme even if it is installed on the local system.
The Debian hardening-includes package sets CFLAGS and LDFLAGS as follows for PIE support:
_HARDENED_PIE_CFLAGS := -fPIE
_HARDENED_PIE_LDFLAGS := -fPIE -pie
The configure.ac file has been updated to conform to the above.
- [client+server] Fernando Arnaboldi from IOActive found that strict
filesystem permissions for various fwknop files are not verified. Added
warnings whenever permissions are not strict enough, and ensured that
files created by the fwknop client and server are only set to user
read/write.
- [client] Fernando Arnaboldi from IOActive found a local buffer overflow
in --last processing with a maliciously constructed ~/.fwknop.run file.
This has been fixed with proper validation of .fwknop.run arguments.
Added --enable-profile-coverage to the configure script to have the fwknop
binaries compiled with gcc profiling support in order to see which functions
get executed by the test suite via gcov. The last test executed by the test
suite under --enable-profile-coverage contains all fwknop functions that
were not executed under the test run (function execution totals are
cumlative).
Commit 4248b2687054b38e79e2ab9eecf71e5b299172f4 removed read-only relocations
and immediate bindings for FreeBSD systems (and the same was done for OpenBSD
systems too). This commit adds these security features back in as linker
options by only changing LDFLAGS as opposed to also adding the corresponding
flags to CFLAGS. The end result is that the following errors are fixed:
gcc: -z: linker input file unused because linking not done
gcc: relro: linker input file unused because linking not done
Similarly to FreeBSD systems, gcc throws the following warnings with read-only
relcations and immediate binding protections - disbabled for now:
gcc: -z: linker input file unused because linking not done
gcc: relro: linker input file unused because linking not done
gcc: -z: linker input file unused because linking not done
gcc: now: linker input file unused because linking not done
If gpgme is installed on FreeBSD systems it appears that
-I/usr/local/include/gpgme must be added to the include path, but this change
only adds the path if gpgme is installed and going to be used.
gcc on FreeBSD generates the following errors when the -Wl,-z,relro -Wl,-z,now
flags are used:
gcc: -z: linker input file unused because linking not done
gcc: relro: linker input file unused because linking not done
gcc: -z: linker input file unused because linking not done
gcc: now: linker input file unused because linking not done
The ./configure script would generate the following error for the attempted
use of the --without-stackprotector (and other related options like
--without-pie):
configure: WARNING: unrecognized options: --without-stackprotect
Added various security options that can be enabled at compile time. These
options include everything that the "hardening-check" script written by Kees
Cook checks for. After this change, the hardening-check script produces the
following output against the fwknopd binary:
$ hardening-check server/.libs/fwknopd
server/.libs/fwknopd:
Position Independent Executable: yes
Stack protected: yes
Fortify Source functions: yes
Read-only relocations: yes
Immediate binding: yes
One of the compile outputs (for example) that shows the new options is:
/bin/bash ../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -fstack-protector-all -fPIE -pie -D_FORTIFY_SOURCE=2 -Wl,-z,relro -Wl,-z,now -MT fko_decode.lo -MD -MP -MF .deps/fko_decode.Tpo -c -o fko_decode.lo fko_decode.c
From the hardening-check man page, here is a description of each of these
options:
NAME
hardening-check - check binaries for security hardening features
SYNOPSIS
Examine a given set of ELF binaries and check for several security
hardening features, failing if they are not all found.
DESCRIPTION
This utility checks a given list of ELF binaries for several security
hardening features that can be compiled into an executable. These
features are:
Position Independent Executable
This indicates that the executable was built in such a way
(PIE) that the "text" section of the program can be relocated
in memory. To take full advantage of this feature, the
executing kernel must support text Address Space Layout
Randomization (ASLR).
Stack Protected
This indicates that the executable was compiled with the
gcc(1) option -fstack-protector. The program will be
resistant to have its stack overflowed.
Fortify Source functions
This indicates that the executable was compiled with
-D_FORTIFY_SOURCE=2 and -O2 or higher. This causes certain
unsafe glibc functions with their safer counterparts (e.g.
strncpy instead of strcpy).
Read-only relocations
This indicates that the executable was build with -Wl,-z,relro
to have ELF markings (RELRO) that ask the runtime linker to
mark any regions of the relocation table as "read-only" if
they were resolved before execution begins. This reduces the
possible areas of memory in a program that can be used by an
attacker that performs a successful memory corruption exploit.
Immediate binding
This indicates that the executable was built with -Wl,-z,now
to have ELF markings (BIND_NOW) that ask the runtime linker to
resolve all relocations before starting program execution.
When combined with RELRO above, this further reduces the
regions of memory available to memory corruption attacks.
