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

From: Benjamin Marzinski <bmarzins@redhat.com>
To: mwilck@suse.com
Cc: dm-devel@redhat.com
Subject: Re: [dm-devel] [PATCH 6/7] multipath-tools: make sure plugin DSOs use symbol versions
Date: Fri, 18 Dec 2020 12:36:33 -0600	[thread overview]
Message-ID: <20201218183633.GM3103@octiron.msp.redhat.com> (raw)
In-Reply-To: <20201217110018.3347-7-mwilck@suse.com>

On Thu, Dec 17, 2020 at 12:00:17PM +0100, mwilck@suse.com wrote:
> From: Martin Wilck <mwilck@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.
> 
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
> Signed-off-by: Martin Wilck <mwilck@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

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