[PATCH] libselinux: Add EXTRA_LD_SONAME_FLAGS for musl+llvm builds

[PATCH] libselinux: Add EXTRA_LD_SONAME_FLAGS for musl+llvm builds

[Stephen Smalley]

Introduce an optionally defined EXTRA_LD_SONAME_FLAGS variable for use
by musl+llvm builds to pass --undefined-version. This enables such
builds to link despite the intentionally omitted
matchpathcon_filespec_add64 symbol.

Fixes: https://github.com/SELinuxProject/selinux/issues/512
Fixes: https://github.com/SELinuxProject/selinux/pull/513
Link: https://lore.kernel.org/selinux/871pe7n3w3.fsf@redhat.com/
Fixes: 9395cc03226a0 ("Always build for LFS mode on 32-bit archs.")
Reported-by: Pepper Gray <hello@peppergray.xyz>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
---
 README.md               | 4 ++++
 libselinux/src/Makefile | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 5e65a049..a458a930 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,10 @@ set when overriding are:
 - -fno-semantic-interposition for gcc or compilers that do not do this. clang does this by default. clang-10 and up
    will support passing this flag, but ignore it. Previous clang versions fail.
 
+## Setting EXTRA_LD_SONAME_FLAGS
+
+Build with EXTRA_LD_SONAME_FLAGS=--undefined-version to fix
+linking against musl with llvm.
 
 macOS
 -----
diff --git a/libselinux/src/Makefile b/libselinux/src/Makefile
index 9982faad..fe8d3239 100644
--- a/libselinux/src/Makefile
+++ b/libselinux/src/Makefile
@@ -91,7 +91,9 @@ CFLAGS ?= -O -Wall -W -Wundef -Wformat-y2k -Wformat-security -Winit-self -Wmissi
 
 override CFLAGS += $(LFS_CFLAGS)
 
-LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro
+# Use make EXTRA_LD_SONAME_FLAGS=--undefined-version to fix
+# linking against musl with llvm.
+LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro$(EXTRA_LD_SONAME_FLAGS)
 
 ifeq ($(OS), Darwin)
 override CFLAGS += -I/opt/local/include
-- 
2.54.0

Re: [PATCH] libselinux: Add EXTRA_LD_SONAME_FLAGS for musl+llvm builds

[Petr Lautrbach]

Stephen Smalley <stephen.smalley.work@gmail.com> writes:

> Introduce an optionally defined EXTRA_LD_SONAME_FLAGS variable for use
> by musl+llvm builds to pass --undefined-version. This enables such
> builds to link despite the intentionally omitted
> matchpathcon_filespec_add64 symbol.
>
> Fixes: https://github.com/SELinuxProject/selinux/issues/512
> Fixes: https://github.com/SELinuxProject/selinux/pull/513
> Link: https://lore.kernel.org/selinux/871pe7n3w3.fsf@redhat.com/
> Fixes: 9395cc03226a0 ("Always build for LFS mode on 32-bit archs.")
> Reported-by: Pepper Gray <hello@peppergray.xyz>
> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> ---
>  README.md               | 4 ++++
>  libselinux/src/Makefile | 4 +++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/README.md b/README.md
> index 5e65a049..a458a930 100644
> --- a/README.md
> +++ b/README.md
> @@ -151,6 +151,10 @@ set when overriding are:
>  - -fno-semantic-interposition for gcc or compilers that do not do this. clang does this by default. clang-10 and up
>     will support passing this flag, but ignore it. Previous clang versions fail.
>  
> +## Setting EXTRA_LD_SONAME_FLAGS
> +
> +Build with EXTRA_LD_SONAME_FLAGS=--undefined-version to fix
> +linking against musl with llvm.
>  
>  macOS
>  -----
> diff --git a/libselinux/src/Makefile b/libselinux/src/Makefile
> index 9982faad..fe8d3239 100644
> --- a/libselinux/src/Makefile
> +++ b/libselinux/src/Makefile
> @@ -91,7 +91,9 @@ CFLAGS ?= -O -Wall -W -Wundef -Wformat-y2k -Wformat-security -Winit-self -Wmissi
>  
>  override CFLAGS += $(LFS_CFLAGS)
>  
> -LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro
> +# Use make EXTRA_LD_SONAME_FLAGS=--undefined-version to fix
> +# linking against musl with llvm.
> +LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro$(EXTRA_LD_SONAME_FLAGS)

I guess there would be missing ',' before --undefined-version

something like this could fix it:

+LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro$(EXTRA_LD_SONAME_FLAGS:%=,%)


>  ifeq ($(OS), Darwin)
>  override CFLAGS += -I/opt/local/include
> -- 
> 2.54.0