selftests/bpf: Add test for freplace program with expected_attach_type

This adds a new selftest that tests the ability to attach an freplace
program to a program type that relies on the expected_attach_type of the
target program to pass verification.

Signed-off-by: Toke Høiland-Jørgensen <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

···
 static void test_fexit_bpf2bpf_common(const char *obj_file,
 				      const char *target_obj_file,
 				      int prog_cnt,
-				      const char **prog_name)
+				      const char **prog_name,
+				      bool run_prog)
 {
 	struct bpf_object *obj = NULL, *pkt_obj;
 	int err, pkt_fd, i;
···
 
 	err = bpf_prog_load(target_obj_file, BPF_PROG_TYPE_UNSPEC,
 			    &pkt_obj, &pkt_fd);
-	if (CHECK(err, "prog_load sched cls", "err %d errno %d\n", err, errno))
+	if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",
+		  target_obj_file, err, errno))
 		return;
 	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
 			    .attach_prog_fd = pkt_fd,
···
 
 	obj = bpf_object__open_file(obj_file, &opts);
 	if (CHECK(IS_ERR_OR_NULL(obj), "obj_open",
-		  "failed to open fexit_bpf2bpf: %ld\n",
+		  "failed to open %s: %ld\n", obj_file,
 		  PTR_ERR(obj)))
 		goto close_prog;
 
···
 		if (CHECK(IS_ERR(link[i]), "attach_trace", "failed to link\n"))
 			goto close_prog;
 	}
+
+	if (!run_prog)
+		goto close_prog;
+
 	data_map = bpf_object__find_map_by_name(obj, "fexit_bp.bss");
 	if (CHECK(!data_map, "find_data_map", "data map not found\n"))
 		goto close_prog;
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf_simple.o",
 				  "./test_pkt_md_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name);
+				  prog_name, true);
 }
 
 static void test_target_yes_callees(void)
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
 				  "./test_pkt_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name);
+				  prog_name, true);
 }
 
 static void test_func_replace(void)
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
 				  "./test_pkt_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name);
+				  prog_name, true);
+}
+
+static void test_func_replace_verify(void)
+{
+	const char *prog_name[] = {
+		"freplace/do_bind",
+	};
+	test_fexit_bpf2bpf_common("./freplace_connect4.o",
+				  "./connect4_prog.o",
+				  ARRAY_SIZE(prog_name),
+				  prog_name, false);
 }
 
 void test_fexit_bpf2bpf(void)
···
 	test_target_no_callees();
 	test_target_yes_callees();
 	test_func_replace();
+	test_func_replace_verify();
 }

tools/testing/selftests/bpf/progs/connect4_prog.c

···
 
 int _version SEC("version") = 1;
 
+__attribute__ ((noinline))
+int do_bind(struct bpf_sock_addr *ctx)
+{
+	struct sockaddr_in sa = {};
+
+	sa.sin_family = AF_INET;
+	sa.sin_port = bpf_htons(0);
+	sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
+
+	if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
+		return 0;
+
+	return 1;
+}
+
 SEC("cgroup/connect4")
 int connect_v4_prog(struct bpf_sock_addr *ctx)
 {
 	struct bpf_sock_tuple tuple = {};
-	struct sockaddr_in sa;
 	struct bpf_sock *sk;
 
 	/* Verify that new destination is available. */
···
 	ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
 	ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
 
-	/* Rewrite source. */
-	memset(&sa, 0, sizeof(sa));
-
-	sa.sin_family = AF_INET;
-	sa.sin_port = bpf_htons(0);
-	sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
-
-	if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
-		return 0;
-
-	return 1;
+	return do_bind(ctx) ? 1 : 0;
 }
 
 char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/freplace_connect4.c

···
+#include <linux/stddef.h>
+#include <linux/ipv6.h>
+#include <linux/bpf.h>
+#include <linux/in.h>
+#include <sys/socket.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+SEC("freplace/do_bind")
+int new_do_bind(struct bpf_sock_addr *ctx)
+{
+  struct sockaddr_in sa = {};
+
+  bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa));
+  return 0;
+}
+
+char _license[] SEC("license") = "GPL";