By passing the flags -z relro -z now to the linker, we can force it to resolve all library symbols at startup, instead of on-demand. This allows it to then make the global offset table (GOT) read-only, which makes some security attacks harder. Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx> --- configure.ac | 1 + m4/virt-linker-relro.m4 | 35 +++++++++++++++++++++++++++++++++++ src/Makefile.am | 4 +++- 3 files changed, 39 insertions(+), 1 deletion(-) create mode 100644 m4/virt-linker-relro.m4 diff --git a/configure.ac b/configure.ac index 4c96fbe..b9ccf93 100644 --- a/configure.ac +++ b/configure.ac @@ -37,6 +37,7 @@ PKG_CHECK_MODULES(LIBVIRT, libvirt >= $LIBVIRT_REQUIRED) PKG_CHECK_MODULES(SYSTEMD, libsystemd >= $SYSTEMD_REQUIRED) LIBVIRT_COMPILE_WARNINGS +LIBVIRT_LINKER_RELRO AC_ARG_WITH(dbus-services, [AC_HELP_STRING([--with-dbus-services=<dir>], diff --git a/m4/virt-linker-relro.m4 b/m4/virt-linker-relro.m4 new file mode 100644 index 0000000..7669b23 --- /dev/null +++ b/m4/virt-linker-relro.m4 @@ -0,0 +1,35 @@ +dnl +dnl Check for -z now and -z relro linker flags +dnl +dnl Copyright (C) 2013 Red Hat, Inc. +dnl +dnl This library is free software; you can redistribute it and/or +dnl modify it under the terms of the GNU Lesser General Public +dnl License as published by the Free Software Foundation; either +dnl version 2.1 of the License, or (at your option) any later version. +dnl +dnl This library is distributed in the hope that it will be useful, +dnl but WITHOUT ANY WARRANTY; without even the implied warranty of +dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +dnl Lesser General Public License for more details. +dnl +dnl You should have received a copy of the GNU Lesser General Public +dnl License along with this library. If not, see +dnl <http://www.gnu.org/licenses/>. +dnl + +AC_DEFUN([LIBVIRT_LINKER_RELRO],[ + AC_MSG_CHECKING([for how to force completely read-only GOT table]) + + RELRO_LDFLAGS= + ld_help=`ld --help 2>&1` + case $ld_help in + *"-z relro"*) RELRO_LDFLAGS="-Wl,-z -Wl,relro" ;; + esac + case $ld_help in + *"-z now"*) RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now" ;; + esac + AC_SUBST([RELRO_LDFLAGS]) + + AC_MSG_RESULT([$RELRO_LDFLAGS]) +]) diff --git a/src/Makefile.am b/src/Makefile.am index 17b4fe1..8dd8ecd 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -24,7 +24,9 @@ libvirt_dbus_CFLAGS = \ libvirt_dbus_LDFLAGS = \ $(SYSTEMD_LDFLAGS) \ - $(LIBVIRT_LDFLAGS) + $(LIBVIRT_LDFLAGS) \ + $(RELRO_LDFLAGS) \ + $(NULL) libvirt_dbus_LDADD = \ $(SYSTEMD_LIBS) \ -- 2.13.6 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
