tc: {f,m}_bpf: allow to retrieve uds path from env

Allow to retrieve uds path from the environment, facilitates
also dealing with export a bit.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tc/f_bpf.c

@@ -122,6 +122,7 @@ opt_bpf:
 
 			NEXT_ARG();
 			if (ebpf) {
+				bpf_uds_name = secure_getenv(BPF_ENV_UDS);
 				bpf_obj = *argv;
 				NEXT_ARG();
 
@@ -131,8 +132,9 @@ opt_bpf:
 					bpf_sec_name = *argv;
 					NEXT_ARG();
 				}
-				if (strcmp(*argv, "export") == 0 ||
-				    strcmp(*argv, "exp") == 0) {
+				if (!bpf_uds_name &&
+				    (strcmp(*argv, "export") == 0 ||
+				     strcmp(*argv, "exp") == 0)) {
 					NEXT_ARG();
 					bpf_uds_name = *argv;
 					NEXT_ARG();

tc/m_bpf.c

@@ -105,6 +105,7 @@ opt_bpf:
 
 			NEXT_ARG();
 			if (ebpf) {
+				bpf_uds_name = secure_getenv(BPF_ENV_UDS);
 				bpf_obj = *argv;
 				NEXT_ARG();
 
@@ -114,8 +115,9 @@ opt_bpf:
 					bpf_sec_name = *argv;
 					NEXT_ARG();
 				}
-				if (strcmp(*argv, "export") == 0 ||
-				    strcmp(*argv, "exp") == 0) {
+				if (!bpf_uds_name &&
+				    (strcmp(*argv, "export") == 0 ||
+				     strcmp(*argv, "exp") == 0)) {
 					NEXT_ARG();
 					bpf_uds_name = *argv;
 					NEXT_ARG();

tc/tc_bpf.h

@@ -25,6 +25,8 @@
 #include "utils.h"
 #include "bpf_scm.h"
 
+#define BPF_ENV_UDS	"TC_BPF_UDS"
+
 int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len,
 		     char **bpf_string, bool *need_release,
 		     const char separator);