build: passing the "-z defs" linker flag to prevent undefined symbols

Undefined symbols are a bad thing in general because they can get
resolved in unexpected ways at runtime if multiple sources provide the
same symbol name. For example both glibc and libtirpc may provide XDR
symbols and we want to ensure that we resolve to libtirpc if that's what
we originally built against.

The toolchain maintainers thus strongly recommend that all applications
use the '-z defs' linker flag to prevent undefined symbols. This is
shortly becoming part of the default linker flags for RPMs. As an added
benefit this aligns Linux builds with Windows builds, where the linker
has never permitted undefined symbols.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

diff --git a/configure.ac b/configure.ac
index 4cccf7f4de53212ae8dd931bd7e903e864e399aa..7997ec5a146150ae4373fa2ec591998e07b78473 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -237,6 +237,7 @@ LIBVIRT_COMPILE_WARNINGS
 LIBVIRT_COMPILE_PIE
 LIBVIRT_LINKER_RELRO
 LIBVIRT_LINKER_NO_INDIRECT
+LIBVIRT_LINKER_NO_UNDEFINED
 
 LIBVIRT_ARG_APPARMOR
 LIBVIRT_ARG_ATTR

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 9c1dfcfac656d1ff9674a16061fb73d095dee697..77dfd8943a173d5835c7b9aa431b6cf03c282a96 100644 (file)
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -125,6 +125,7 @@ libvirtd_conf_la_LDFLAGS = \
        $(PIE_LDFLAGS) \
        $(COVERAGE_LDFLAGS) \
        $(NO_INDIRECT_LDFLAGS) \
+       $(NO_UNDEFINED_LDFLAGS) \
        $(NULL)
 libvirtd_conf_la_LIBADD = $(LIBXML_LIBS)
 
@@ -158,6 +159,7 @@ libvirtd_LDFLAGS = \
        $(PIE_LDFLAGS) \
        $(COVERAGE_LDFLAGS) \
        $(NO_INDIRECT_LDFLAGS) \
+       $(NO_UNDEFINED_LDFLAGS) \
        $(NULL)
 
 libvirtd_LDADD = \

diff --git a/m4/virt-linker-no-undefined.m4 b/m4/virt-linker-no-undefined.m4
new file mode 100644 (file)
index 0000000..532b0de
--- /dev/null
+++ b/m4/virt-linker-no-undefined.m4
@@ -0,0 +1,32 @@
+dnl
+dnl Check for -z defs linker flag
+dnl
+dnl Copyright (C) 2013-2018 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_NO_UNDEFINED],[
+    AC_MSG_CHECKING([for how to stop undefined symbols at link time])
+
+    NO_UNDEFINED_LDFLAGS=
+    ld_help=`$LD --help 2>&1`
+    case $ld_help in
+        *"-z defs"*) NO_UNDEFINED_LDFLAGS="-Wl,-z -Wl,defs" ;;
+    esac
+    AC_SUBST([NO_UNDEFINED_LDFLAGS])
+
+    AC_MSG_RESULT([$NO_UNDEFINED_LDFLAGS])
+])

diff --git a/src/Makefile.am b/src/Makefile.am
index 38efde012eb5d69e4b8bfb0c124e54e189a5b773..2cfa36a142d5ff72847a1fa7f3dc7ee473fff7dd 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -52,6 +52,7 @@ AM_LDFLAGS =  $(DRIVER_MODULES_LDFLAGS) \
                $(MINGW_EXTRA_LDFLAGS) \
                $(NULL)
 AM_LDFLAGS_MOD = -module -avoid-version $(AM_LDFLAGS)
+AM_LDFLAGS_MOD_NOUNDEF = $(AM_LDFLAGS_MOD) $(NO_UNDEFINED_LDFLAGS)
 
 POD2MAN = pod2man -c "Virtualization Support" -r "$(PACKAGE)-$(VERSION)"
 
@@ -1342,7 +1343,7 @@ libvirt_driver_xen_la_SOURCES =
 libvirt_driver_xen_la_LIBADD = libvirt_driver_xen_impl.la
 mod_LTLIBRARIES += libvirt_driver_xen.la
 libvirt_driver_xen_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_xen_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_xen_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_xen_impl_la_CFLAGS = \
                $(XEN_CFLAGS) \
@@ -1388,7 +1389,7 @@ libvirt_driver_vbox_la_LIBADD = libvirt_driver_vbox_impl.la
 mod_LTLIBRARIES += \
                libvirt_driver_vbox.la
 libvirt_driver_vbox_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_vbox_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_vbox_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_vbox_impl_la_CFLAGS = \
                -I$(srcdir)/conf \
@@ -1417,10 +1418,11 @@ libvirt_driver_libxl_la_SOURCES =
 libvirt_driver_libxl_la_LIBADD = libvirt_driver_libxl_impl.la
 mod_LTLIBRARIES += libvirt_driver_libxl.la
 libvirt_driver_libxl_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_libxl_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_libxl_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_libxl_impl_la_CFLAGS = \
                $(LIBXL_CFLAGS) \
+               $(LIBXML_CFLAGS) \
                -I$(srcdir)/access \
                -I$(srcdir)/conf \
                -I$(srcdir)/secret \
@@ -1428,6 +1430,7 @@ libvirt_driver_libxl_impl_la_CFLAGS = \
                $(AM_CFLAGS)
 libvirt_driver_libxl_impl_la_LDFLAGS = $(AM_LDFLAGS)
 libvirt_driver_libxl_impl_la_LIBADD = $(LIBXL_LIBS) \
+                                     $(LIBXML_LIBS) \
                                      libvirt_xenconfig_libxl.la
 libvirt_driver_libxl_impl_la_SOURCES = $(LIBXL_DRIVER_SOURCES)
 
@@ -1446,11 +1449,12 @@ libvirt_driver_qemu_la_SOURCES =
 libvirt_driver_qemu_la_LIBADD = libvirt_driver_qemu_impl.la
 mod_LTLIBRARIES += libvirt_driver_qemu.la
 libvirt_driver_qemu_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_qemu_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_qemu_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_qemu_impl_la_CFLAGS = \
                $(GNUTLS_CFLAGS) \
                $(LIBNL_CFLAGS) \
+               $(SELINUX_CFLAGS) \
                $(XDR_CFLAGS) \
                -I$(srcdir)/access \
                -I$(srcdir)/conf \
@@ -1460,6 +1464,7 @@ libvirt_driver_qemu_impl_la_LDFLAGS = $(AM_LDFLAGS)
 libvirt_driver_qemu_impl_la_LIBADD = $(CAPNG_LIBS) \
                                 $(GNUTLS_LIBS) \
                                $(LIBNL_LIBS) \
+                               $(SELINUX_LIBS) \
                                $(LIBXML_LIBS) \
                                $(NULL)
 libvirt_driver_qemu_impl_la_SOURCES = $(QEMU_DRIVER_SOURCES)
@@ -1481,7 +1486,7 @@ libvirt_driver_lxc_la_SOURCES =
 libvirt_driver_lxc_la_LIBADD = libvirt_driver_lxc_impl.la
 mod_LTLIBRARIES += libvirt_driver_lxc.la
 libvirt_driver_lxc_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_lxc_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_lxc_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_lxc_impl_la_CFLAGS = \
                $(LIBNL_CFLAGS) \
@@ -1518,7 +1523,7 @@ libvirt_driver_uml_la_SOURCES =
 libvirt_driver_uml_la_LIBADD = libvirt_driver_uml_impl.la
 mod_LTLIBRARIES += libvirt_driver_uml.la
 libvirt_driver_uml_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_uml_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_uml_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_uml_impl_la_CFLAGS = \
                -I$(srcdir)/access \
@@ -1590,7 +1595,7 @@ libvirt_driver_vz_la_SOURCES =
 libvirt_driver_vz_la_LIBADD = libvirt_driver_vz_impl.la
 mod_LTLIBRARIES += libvirt_driver_vz.la
 libvirt_driver_vz_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_vz_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_vz_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_vz_impl_la_CFLAGS = \
                -I$(srcdir)/conf \
                -I$(srcdir)/access \
@@ -1606,7 +1611,7 @@ libvirt_driver_bhyve_la_SOURCES =
 libvirt_driver_bhyve_la_LIBADD = libvirt_driver_bhyve_impl.la
 mod_LTLIBRARIES += libvirt_driver_bhyve.la
 libvirt_driver_bhyve_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_bhyve_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_bhyve_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_bhyve_impl_la_CFLAGS = \
        -I$(srcdir)/access \
@@ -1632,7 +1637,7 @@ libvirt_driver_network_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la \
        $(LIBNL_LIBS) \
        $(DBUS_LIBS) \
        $(NULL)
-libvirt_driver_network_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_network_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 
 libvirt_driver_network_impl_la_CFLAGS = \
                $(LIBNL_CFLAGS) \
@@ -1652,7 +1657,7 @@ libvirt_driver_interface_la_CFLAGS = \
                -I$(srcdir)/access \
                -I$(srcdir)/conf \
                $(AM_CFLAGS) $(LIBNL_CFLAGS)
-libvirt_driver_interface_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_interface_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_interface_la_LIBADD =
 if WITH_NETCF
 libvirt_driver_interface_la_CFLAGS += $(NETCF_CFLAGS)
@@ -1673,7 +1678,7 @@ libvirt_driver_secret_la_CFLAGS = \
                -I$(srcdir)/conf \
                $(AM_CFLAGS)
 libvirt_driver_secret_la_LIBADD = libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_secret_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_secret_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_secret_la_SOURCES = $(SECRET_DRIVER_SOURCES)
 endif WITH_SECRETS
 
@@ -1701,7 +1706,7 @@ libvirt_driver_storage_la_SOURCES =
 libvirt_driver_storage_la_LIBADD = libvirt_driver_storage_impl.la
 mod_LTLIBRARIES += libvirt_driver_storage.la
 libvirt_driver_storage_la_LIBADD += libvirt.la ../gnulib/lib/libgnu.la
-libvirt_driver_storage_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_storage_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_storage_impl_la_SOURCES += $(STORAGE_DRIVER_SOURCES)
 
 
@@ -1855,7 +1860,7 @@ libvirt_driver_nodedev_la_CFLAGS = \
                -I$(srcdir)/access \
                -I$(srcdir)/conf \
                $(AM_CFLAGS) $(LIBNL_CFLAGS)
-libvirt_driver_nodedev_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_nodedev_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_nodedev_la_LIBADD =
 
 if WITH_LIBVIRTD
@@ -1880,7 +1885,7 @@ noinst_LTLIBRARIES += libvirt_driver_nwfilter_impl.la
 libvirt_driver_nwfilter_la_SOURCES =
 libvirt_driver_nwfilter_la_LIBADD = libvirt_driver_nwfilter_impl.la
 mod_LTLIBRARIES += libvirt_driver_nwfilter.la
-libvirt_driver_nwfilter_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+libvirt_driver_nwfilter_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 libvirt_driver_nwfilter_impl_la_CFLAGS = \
                $(LIBPCAP_CFLAGS) \
                $(LIBNL_CFLAGS) \
@@ -2389,6 +2394,7 @@ libvirt_la_LDFLAGS = \
                $(VERSION_SCRIPT_FLAGS)$(LIBVIRT_SYMBOL_FILE) \
                -version-info $(LIBVIRT_VERSION_INFO) \
                $(LIBVIRT_NODELETE) \
+               $(NO_UNDEFINED_LDFLAGS) \
                $(AM_LDFLAGS) \
                $(NULL)
 libvirt_la_BUILT_LIBADD += ../gnulib/lib/libgnu.la
@@ -2591,7 +2597,7 @@ lockd_la_SOURCES = \
 lockd_la_CFLAGS = -I$(srcdir)/conf \
                $(XDR_CFLAGS) \
                $(AM_CFLAGS)
-lockd_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+lockd_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 lockd_la_LIBADD = libvirt.la ../gnulib/lib/libgnu.la
 augeas_DATA += locking/libvirt_lockd.aug
 if WITH_DTRACE_PROBES
@@ -2631,6 +2637,7 @@ virtlockd_CFLAGS = \
 virtlockd_LDFLAGS = \
                $(AM_LDFLAGS) \
                $(PIE_LDFLAGS) \
+               $(NO_UNDEFINED_LDFLAGS) \
                $(NULL)
 virtlockd_LDADD = \
                libvirt_driver_admin.la \
@@ -2658,6 +2665,7 @@ virtlogd_CFLAGS = \
 virtlogd_LDFLAGS = \
                $(AM_LDFLAGS) \
                $(PIE_LDFLAGS) \
+               $(NO_UNDEFINED_LDFLAGS) \
                $(NULL)
 virtlogd_LDADD = \
                libvirt_driver_admin.la \
@@ -2872,7 +2880,7 @@ if WITH_SANLOCK
 lockdriver_LTLIBRARIES += sanlock.la
 sanlock_la_SOURCES = $(LOCK_DRIVER_SANLOCK_SOURCES)
 sanlock_la_CFLAGS = -I$(srcdir)/conf $(AM_CFLAGS)
-sanlock_la_LDFLAGS = $(AM_LDFLAGS_MOD)
+sanlock_la_LDFLAGS = $(AM_LDFLAGS_MOD_NOUNDEF)
 sanlock_la_LIBADD = -lsanlock_client libvirt.la ../gnulib/lib/libgnu.la
 
 augeas_DATA += locking/libvirt_sanlock.aug

diff --git a/tools/Makefile.am b/tools/Makefile.am
index 4c33e78a1d733ba5965b6847719b6d18077067cf..85e640b9e73c362a9b949ef7cf3c75af25f627c2 100644 (file)
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -35,6 +35,7 @@ AM_CFLAGS = \
 AM_LDFLAGS = \
        $(RELRO_LDFLAGS) \
        $(NO_INDIRECT_LDFLAGS) \
+       $(NO_UNDEFINED_LDFLAGS) \
        $(NULL)
 
 ICON_FILES = \