[PATCH] selftests/bpf/Makefile: fix relative rpath usage

[Eugene Syromiatnikov]

The relative RPATH ("./") supplied to linker options in CFLAGS is resolved
relative to current working directory and not the executable directory,
which will lead in incorrect resolution when the test executable is run
from elsewhere.  Changing it to $ORIGIN makes it resolve relative
to the directory in which the executable resides, which is supposedly
the desired behaviour.

Discovered by the check-rpaths script[1][2] that checks for insecure
RPATH/RUNPATH[3], such as relative directories, during an attempt
to package BPF selftests for later use in CI:

    ERROR   0004: file '/usr/libexec/kselftests/bpf/urandom_read' contains an insecure runpath '.' in [.]

[1] https://github.com/rpm-software-management/rpm/blob/master/scripts/check-rpaths
[2] https://github.com/rpm-software-management/rpm/blob/master/scripts/check-rpaths-worker
[3] https://cwe.mitre.org/data/definitions/426.html

Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index dd49c1d23a60..6a3dc9b99159 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -241,7 +241,7 @@ $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_r
 		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) $(filter %.c,$^) \
 		     -lurandom_read $(filter-out -static,$(LDLIBS)) -L$(OUTPUT) \
 		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
-		     -Wl,-rpath=. -o $@
+		     -Wl,-rpath=\$$ORIGIN/ -o $@
 
 $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c
 	$(call msg,SIGN-FILE,,$@)
-- 
2.28.0