[dm-devel] [PATCH 6/7] multipath-tools: make sure plugin DSOs use symbol versions

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

By adding -Wl,-z,defs, we'll get warnings about unresolved symbols
at the linking stage. This way we make sure our plugins (checkers etc.)
will use versioned symbols from libmultipath, and incompatible plugins
can't be loaded any more. Doing this requires explicitly linking
the plugins with all libraries they use, in particular libmultipath.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 Makefile                           | 1 +
 Makefile.inc                       | 2 +-
 libmpathpersist/Makefile           | 8 ++++----
 libmultipath/checkers/Makefile     | 7 +++----
 libmultipath/foreign/Makefile      | 4 +++-
 libmultipath/prioritizers/Makefile | 7 +++----
 6 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index f127ff9..bddb2bf 100644
--- a/Makefile
+++ b/Makefile
@@ -31,6 +31,7 @@ $(BUILDDIRS):
 
 libmultipath libdmmp: libmpathcmd
 libmpathpersist libmpathvalid multipath multipathd: libmultipath
+libmultipath/prioritizers libmultipath/checkers libmultipath/foreign: libmultipath
 mpathpersist multipathd:  libmpathpersist
 
 libmultipath/checkers.install \
diff --git a/Makefile.inc b/Makefile.inc
index 13587a9..0542930 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -105,7 +105,7 @@ CFLAGS		:= --std=gnu99 $(CFLAGS) $(OPTFLAGS) $(WARNFLAGS) -pipe \
 BIN_CFLAGS	= -fPIE -DPIE
 LIB_CFLAGS	= -fPIC
 SHARED_FLAGS	= -shared
-LDFLAGS		:= $(LDFLAGS) -Wl,-z,relro -Wl,-z,now
+LDFLAGS		:= $(LDFLAGS) -Wl,-z,relro -Wl,-z,now -Wl,-z,defs
 BIN_LDFLAGS	= -pie
 
 # Check whether a function with name $1 has been declared in header file $2.
diff --git a/libmpathpersist/Makefile b/libmpathpersist/Makefile
index 456ce4c..57103e5 100644
--- a/libmpathpersist/Makefile
+++ b/libmpathpersist/Makefile
@@ -6,17 +6,17 @@ LIBS = $(DEVLIB).$(SONAME)
 VERSION_SCRIPT := libmpathpersist.version
 
 CFLAGS += $(LIB_CFLAGS) -I$(multipathdir) -I$(mpathpersistdir) -I$(mpathcmddir)
+LDFLAGS += -L$(multipathdir) -L$(mpathcmddir)
 
-LIBDEPS += -lpthread -ldevmapper -ldl -L$(multipathdir) -lmultipath \
-	   -L$(mpathcmddir) -lmpathcmd
+LIBDEPS += -lmultipath -lmpathcmd -ldevmapper -lpthread -ldl
 
 OBJS = mpath_persist.o mpath_updatepr.o mpath_pr_ioctl.o
 
 all: $(DEVLIB) man
 
 $(LIBS): $(OBJS) $(VERSION_SCRIPT)
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) $(LIBDEPS) -Wl,-soname=$@ \
-		-Wl,--version-script=$(VERSION_SCRIPT) -o $@ $(OBJS)
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -Wl,-soname=$@ \
+		-Wl,--version-script=$(VERSION_SCRIPT) -o $@ $(OBJS) $(LIBDEPS)
 
 $(DEVLIB): $(LIBS)
 	$(LN) $(LIBS) $@
diff --git a/libmultipath/checkers/Makefile b/libmultipath/checkers/Makefile
index 01c0451..8e0ed5e 100644
--- a/libmultipath/checkers/Makefile
+++ b/libmultipath/checkers/Makefile
@@ -4,6 +4,8 @@
 include ../../Makefile.inc
 
 CFLAGS += $(LIB_CFLAGS) -I..
+LDFLAGS += -L.. -lmultipath
+LIBDEPS = -lmultipath -laio -lpthread -lrt
 
 # If you add or remove a checker also update multipath/multipath.conf.5
 LIBS= \
@@ -17,11 +19,8 @@ LIBS= \
 
 all: $(LIBS)
 
-libcheckdirectio.so: directio.o
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^ -laio
-
 libcheck%.so: %.o
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^ $(LIBDEPS)
 
 install:
 	$(INSTALL_PROGRAM) -m 755 $(LIBS) $(DESTDIR)$(libdir)
diff --git a/libmultipath/foreign/Makefile b/libmultipath/foreign/Makefile
index fae58a0..f447a1c 100644
--- a/libmultipath/foreign/Makefile
+++ b/libmultipath/foreign/Makefile
@@ -5,13 +5,15 @@ TOPDIR=../..
 include ../../Makefile.inc
 
 CFLAGS += $(LIB_CFLAGS) -I.. -I$(nvmedir)
+LDFLAGS += -L..
+LIBDEPS = -lmultipath -ludev -lpthread -lrt
 
 LIBS = libforeign-nvme.so
 
 all: $(LIBS)
 
 libforeign-%.so: %.o
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^ $(LIBDEPS)
 
 install:
 	$(INSTALL_PROGRAM) -m 755 $(LIBS) $(DESTDIR)$(libdir)
diff --git a/libmultipath/prioritizers/Makefile b/libmultipath/prioritizers/Makefile
index fc6e0e0..8d34ae3 100644
--- a/libmultipath/prioritizers/Makefile
+++ b/libmultipath/prioritizers/Makefile
@@ -4,6 +4,8 @@
 include ../../Makefile.inc
 
 CFLAGS += $(LIB_CFLAGS) -I..
+LDFLAGS += -L..
+LIBDEPS = -lmultipath -lm -lpthread -lrt
 
 # If you add or remove a prioritizer also update multipath/multipath.conf.5
 LIBS = \
@@ -28,11 +30,8 @@ endif
 
 all: $(LIBS)
 
-libpriopath_latency.so: path_latency.o
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^ -lm
-
 libprio%.so: %.o
-	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^
+	$(CC) $(LDFLAGS) $(SHARED_FLAGS) -o $@ $^ $(LIBDEPS)
 
 install: $(LIBS)
 	$(INSTALL_PROGRAM) -m 755 libprio*.so $(DESTDIR)$(libdir)
-- 
2.29.0