selftests/bpf: add sockopt clone/inheritance test

Add a test that calls setsockopt on the listener socket which triggers
BPF program. This BPF program writes to the sk storage and sets
clone flag. Make sure that sk storage is cloned for a newly
accepted connection.

We have two cloned maps in the tests to make sure we hit both cases
in bpf_sk_storage_clone: first element (sk_storage_alloc) and
non-first element(s) (selem_link_map).

Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/.gitignore

@@ -42,4 +42,5 @@ xdping
 test_sockopt
 test_sockopt_sk
 test_sockopt_multi
+test_sockopt_inherit
 test_tcp_rtt

tools/testing/selftests/bpf/Makefile

@@ -29,7 +29,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_cgroup_storage test_select_reuseport test_section_names \
 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
 	test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk \
-	test_sockopt_multi test_tcp_rtt
+	test_sockopt_multi test_sockopt_inherit test_tcp_rtt
 
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
@@ -111,6 +111,7 @@ $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
 $(OUTPUT)/test_sockopt: cgroup_helpers.c
 $(OUTPUT)/test_sockopt_sk: cgroup_helpers.c
 $(OUTPUT)/test_sockopt_multi: cgroup_helpers.c
+$(OUTPUT)/test_sockopt_inherit: cgroup_helpers.c
 $(OUTPUT)/test_tcp_rtt: cgroup_helpers.c
 
 .PHONY: force

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

@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;
+
+#define SOL_CUSTOM			0xdeadbeef
+#define CUSTOM_INHERIT1			0
+#define CUSTOM_INHERIT2			1
+#define CUSTOM_LISTENER			2
+
+struct sockopt_inherit {
+	__u8 val;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
+	__type(key, int);
+	__type(value, struct sockopt_inherit);
+} cloned1_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
+	__type(key, int);
+	__type(value, struct sockopt_inherit);
+} cloned2_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct sockopt_inherit);
+} listener_only_map SEC(".maps");
+
+static __inline struct sockopt_inherit *get_storage(struct bpf_sockopt *ctx)
+{
+	if (ctx->optname == CUSTOM_INHERIT1)
+		return bpf_sk_storage_get(&cloned1_map, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+	else if (ctx->optname == CUSTOM_INHERIT2)
+		return bpf_sk_storage_get(&cloned2_map, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+	else
+		return bpf_sk_storage_get(&listener_only_map, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+}
+
+SEC("cgroup/getsockopt")
+int _getsockopt(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	struct sockopt_inherit *storage;
+	__u8 *optval = ctx->optval;
+
+	if (ctx->level != SOL_CUSTOM)
+		return 1; /* only interested in SOL_CUSTOM */
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	storage = get_storage(ctx);
+	if (!storage)
+		return 0; /* EPERM, couldn't get sk storage */
+
+	ctx->retval = 0; /* Reset system call return value to zero */
+
+	optval[0] = storage->val;
+	ctx->optlen = 1;
+
+	return 1;
+}
+
+SEC("cgroup/setsockopt")
+int _setsockopt(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	struct sockopt_inherit *storage;
+	__u8 *optval = ctx->optval;
+
+	if (ctx->level != SOL_CUSTOM)
+		return 1; /* only interested in SOL_CUSTOM */
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	storage = get_storage(ctx);
+	if (!storage)
+		return 0; /* EPERM, couldn't get sk storage */
+
+	storage->val = optval[0];
+	ctx->optlen = -1;
+
+	return 1;
+}

tools/testing/selftests/bpf/test_sockopt_inherit.c

@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <error.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <pthread.h>
+
+#include <linux/filter.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "cgroup_helpers.h"
+
+#define CG_PATH				"/sockopt_inherit"
+#define SOL_CUSTOM			0xdeadbeef
+#define CUSTOM_INHERIT1			0
+#define CUSTOM_INHERIT2			1
+#define CUSTOM_LISTENER			2
+
+static int connect_to_server(int server_fd)
+{
+	struct sockaddr_storage addr;
+	socklen_t len = sizeof(addr);
+	int fd;
+
+	fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (fd < 0) {
+		log_err("Failed to create client socket");
+		return -1;
+	}
+
+	if (getsockname(server_fd, (struct sockaddr *)&addr, &len)) {
+		log_err("Failed to get server addr");
+		goto out;
+	}
+
+	if (connect(fd, (const struct sockaddr *)&addr, len) < 0) {
+		log_err("Fail to connect to server");
+		goto out;
+	}
+
+	return fd;
+
+out:
+	close(fd);
+	return -1;
+}
+
+static int verify_sockopt(int fd, int optname, const char *msg, char expected)
+{
+	socklen_t optlen = 1;
+	char buf = 0;
+	int err;
+
+	err = getsockopt(fd, SOL_CUSTOM, optname, &buf, &optlen);
+	if (err) {
+		log_err("%s: failed to call getsockopt", msg);
+		return 1;
+	}
+
+	printf("%s %d: got=0x%x ? expected=0x%x\n", msg, optname, buf, expected);
+
+	if (buf != expected) {
+		log_err("%s: unexpected getsockopt value %d != %d", msg,
+			buf, expected);
+		return 1;
+	}
+
+	return 0;
+}
+
+static void *server_thread(void *arg)
+{
+	struct sockaddr_storage addr;
+	socklen_t len = sizeof(addr);
+	int fd = *(int *)arg;
+	int client_fd;
+	int err = 0;
+
+	if (listen(fd, 1) < 0)
+		error(1, errno, "Failed to listed on socket");
+
+	err += verify_sockopt(fd, CUSTOM_INHERIT1, "listen", 1);
+	err += verify_sockopt(fd, CUSTOM_INHERIT2, "listen", 1);
+	err += verify_sockopt(fd, CUSTOM_LISTENER, "listen", 1);
+
+	client_fd = accept(fd, (struct sockaddr *)&addr, &len);
+	if (client_fd < 0)
+		error(1, errno, "Failed to accept client");
+
+	err += verify_sockopt(client_fd, CUSTOM_INHERIT1, "accept", 1);
+	err += verify_sockopt(client_fd, CUSTOM_INHERIT2, "accept", 1);
+	err += verify_sockopt(client_fd, CUSTOM_LISTENER, "accept", 0);
+
+	close(client_fd);
+
+	return (void *)(long)err;
+}
+
+static int start_server(void)
+{
+	struct sockaddr_in addr = {
+		.sin_family = AF_INET,
+		.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
+	};
+	char buf;
+	int err;
+	int fd;
+	int i;
+
+	fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (fd < 0) {
+		log_err("Failed to create server socket");
+		return -1;
+	}
+
+	for (i = CUSTOM_INHERIT1; i <= CUSTOM_LISTENER; i++) {
+		buf = 0x01;
+		err = setsockopt(fd, SOL_CUSTOM, i, &buf, 1);
+		if (err) {
+			log_err("Failed to call setsockopt(%d)", i);
+			close(fd);
+			return -1;
+		}
+	}
+
+	if (bind(fd, (const struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		log_err("Failed to bind socket");
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+static int prog_attach(struct bpf_object *obj, int cgroup_fd, const char *title)
+{
+	enum bpf_attach_type attach_type;
+	enum bpf_prog_type prog_type;
+	struct bpf_program *prog;
+	int err;
+
+	err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
+	if (err) {
+		log_err("Failed to deduct types for %s BPF program", title);
+		return -1;
+	}
+
+	prog = bpf_object__find_program_by_title(obj, title);
+	if (!prog) {
+		log_err("Failed to find %s BPF program", title);
+		return -1;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
+			      attach_type, 0);
+	if (err) {
+		log_err("Failed to attach %s BPF program", title);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int run_test(int cgroup_fd)
+{
+	struct bpf_prog_load_attr attr = {
+		.file = "./sockopt_inherit.o",
+	};
+	int server_fd = -1, client_fd;
+	struct bpf_object *obj;
+	void *server_err;
+	pthread_t tid;
+	int ignored;
+	int err;
+
+	err = bpf_prog_load_xattr(&attr, &obj, &ignored);
+	if (err) {
+		log_err("Failed to load BPF object");
+		return -1;
+	}
+
+	err = prog_attach(obj, cgroup_fd, "cgroup/getsockopt");
+	if (err)
+		goto close_bpf_object;
+
+	err = prog_attach(obj, cgroup_fd, "cgroup/setsockopt");
+	if (err)
+		goto close_bpf_object;
+
+	server_fd = start_server();
+	if (server_fd < 0) {
+		err = -1;
+		goto close_bpf_object;
+	}
+
+	pthread_create(&tid, NULL, server_thread, (void *)&server_fd);
+
+	client_fd = connect_to_server(server_fd);
+	if (client_fd < 0) {
+		err = -1;
+		goto close_server_fd;
+	}
+
+	err += verify_sockopt(client_fd, CUSTOM_INHERIT1, "connect", 0);
+	err += verify_sockopt(client_fd, CUSTOM_INHERIT2, "connect", 0);
+	err += verify_sockopt(client_fd, CUSTOM_LISTENER, "connect", 0);
+
+	pthread_join(tid, &server_err);
+
+	err += (int)(long)server_err;
+
+	close(client_fd);
+
+close_server_fd:
+	close(server_fd);
+close_bpf_object:
+	bpf_object__close(obj);
+	return err;
+}
+
+int main(int args, char **argv)
+{
+	int cgroup_fd;
+	int err = EXIT_SUCCESS;
+
+	if (setup_cgroup_environment())
+		return err;
+
+	cgroup_fd = create_and_get_cgroup(CG_PATH);
+	if (cgroup_fd < 0)
+		goto cleanup_cgroup_env;
+
+	if (join_cgroup(CG_PATH))
+		goto cleanup_cgroup;
+
+	if (run_test(cgroup_fd))
+		err = EXIT_FAILURE;
+
+	printf("test_sockopt_inherit: %s\n",
+	       err == EXIT_SUCCESS ? "PASSED" : "FAILED");
+
+cleanup_cgroup:
+	close(cgroup_fd);
+cleanup_cgroup_env:
+	cleanup_cgroup_environment();
+	return err;
+}