[PATCH 5.4 26/51] um: allow not setting extra rpaths in the linux binary

Sasha Levin
2024-03-13T17:02:43Z

From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 386093c68ba3e8bcfe7f46deba901e0e80713c29 ]

There doesn't seem to be any reason for the rpath being set in
the binaries, at on systems that I tested on. On the other hand,
setting rpath is actually harming binaries in some cases, e.g.
if using nix-based compilation environments where /lib & /lib64
are not part of the actual environment.

Add a new Kconfig option (under EXPERT, for less user confusion)
that allows disabling the rpath additions.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Stable-dep-of: 846cfbeed09b ("um: Fix adding '-no-pie' for clang")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/um/Kconfig | 13 +++++++++++++
arch/um/Makefile | 3 ++-
arch/x86/Makefile.um | 2 +-
3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 468a5d63ef269..107a0bc668e9f 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -85,6 +85,19 @@ config LD_SCRIPT_DYN
depends on !LD_SCRIPT_STATIC
select MODULE_REL_CRCS if MODVERSIONS

+config LD_SCRIPT_DYN_RPATH
+ bool "set rpath in the binary" if EXPERT
+ default y
+ depends on LD_SCRIPT_DYN
+ help
+ Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
+ explicitly.
+
+ You may need to turn this off if compiling for nix systems
+ that have their libraries in random /nix directories and
+ might otherwise unexpected use libraries from /lib or /lib64
+ instead of the desired ones.
+
config HOSTFS
tristate "Host filesystem"
help
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 773120be0f56f..94cea8d46b222 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -118,7 +118,8 @@ archprepare:
$(Q)$(MAKE) $(build)=$(HOST_DIR)/um include/generated/user_constants.h

LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static
-LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib $(call cc-option, -no-pie)
+LINK-$(CONFIG_LD_SCRIPT_DYN) += $(call cc-option, -no-pie)
+LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib

CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,) \
$(call cc-option, -fno-stack-protector,) \
diff --git a/arch/x86/Makefile.um b/arch/x86/Makefile.um
index 1db7913795f51..b3c1ae084180d 100644
--- a/arch/x86/Makefile.um
+++ b/arch/x86/Makefile.um
@@ -44,7 +44,7 @@ ELF_FORMAT := elf64-x86-64

# Not on all 64-bit distros /lib is a symlink to /lib64. PLD is an example.

-LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib64
+LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64
LINK-y += -m64

endif
--
2.43.0