selftests/bpf: add sockopt test that exercises sk helpers

socktop test that introduces new SOL_CUSTOM sockopt level and
stores whatever users sets in sk storage. Whenever getsockopt
is called, the original value is retrieved.

v9:
* SO_SNDBUF example to override user-supplied buffer

v7:
* use retval=0 and optlen-1

v6:
* test 'ret=1' use-case as well (Alexei Starovoitov)

v4:
* don't call bpf_sk_fullsock helper

v3:
* drop (__u8 *)(long) casts for optval{,_end}

v2:
* new test

Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 214 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/test_sockopt_sk.c b/tools/testing/selftests/bpf/test_sockopt_sk.c
new file mode 100644
index 000000000000..12e79ed075ce
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sockopt_sk.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.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"
+
+#define SOL_CUSTOM			0xdeadbeef
+
+static int getsetsockopt(void)
+{
+	int fd, err;
+	char buf[4] = {};
+	socklen_t optlen;
+
+	fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (fd < 0) {
+		log_err("Failed to create socket");
+		return -1;
+	}
+
+	/* IP_TOS - BPF bypass */
+
+	buf[0] = 0x08;
+	err = setsockopt(fd, SOL_IP, IP_TOS, buf, 1);
+	if (err) {
+		log_err("Failed to call setsockopt(IP_TOS)");
+		goto err;
+	}
+
+	buf[0] = 0x00;
+	optlen = 1;
+	err = getsockopt(fd, SOL_IP, IP_TOS, buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto err;
+	}
+
+	if (buf[0] != 0x08) {
+		log_err("Unexpected getsockopt(IP_TOS) buf[0] 0x%02x != 0x08",
+			buf[0]);
+		goto err;
+	}
+
+	/* IP_TTL - EPERM */
+
+	buf[0] = 1;
+	err = setsockopt(fd, SOL_IP, IP_TTL, buf, 1);
+	if (!err || errno != EPERM) {
+		log_err("Unexpected success from setsockopt(IP_TTL)");
+		goto err;
+	}
+
+	/* SOL_CUSTOM - handled by BPF */
+
+	buf[0] = 0x01;
+	err = setsockopt(fd, SOL_CUSTOM, 0, buf, 1);
+	if (err) {
+		log_err("Failed to call setsockopt");
+		goto err;
+	}
+
+	buf[0] = 0x00;
+	optlen = 4;
+	err = getsockopt(fd, SOL_CUSTOM, 0, buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt");
+		goto err;
+	}
+
+	if (optlen != 1) {
+		log_err("Unexpected optlen %d != 1", optlen);
+		goto err;
+	}
+	if (buf[0] != 0x01) {
+		log_err("Unexpected buf[0] 0x%02x != 0x01", buf[0]);
+		goto err;
+	}
+
+	/* SO_SNDBUF is overwritten */
+
+	buf[0] = 0x01;
+	buf[1] = 0x01;
+	buf[2] = 0x01;
+	buf[3] = 0x01;
+	err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, 4);
+	if (err) {
+		log_err("Failed to call setsockopt(SO_SNDBUF)");
+		goto err;
+	}
+
+	buf[0] = 0x00;
+	buf[1] = 0x00;
+	buf[2] = 0x00;
+	buf[3] = 0x00;
+	optlen = 4;
+	err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(SO_SNDBUF)");
+		goto err;
+	}
+
+	if (*(__u32 *)buf != 0x55AA*2) {
+		log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2",
+			*(__u32 *)buf);
+		goto err;
+	}
+
+	close(fd);
+	return 0;
+err:
+	close(fd);
+	return -1;
+}
+
+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_sk.o",
+	};
+	struct bpf_object *obj;
+	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;
+
+	err = getsetsockopt();
+
+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())
+		goto cleanup_obj;
+
+	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_sk: %s\n",
+	       err == EXIT_SUCCESS ? "PASSED" : "FAILED");
+
+cleanup_cgroup:
+	close(cgroup_fd);
+cleanup_cgroup_env:
+	cleanup_cgroup_environment();
+cleanup_obj:
+	return err;
+}