bpf, testing: Add selftest to read/write sockaddr from user space

// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

void test_probe_user(void)

{

#define kprobe_name "__sys_connect"

	const char *prog_name = "kprobe/" kprobe_name;

	const char *obj_file = "./test_probe_user.o";

	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, );

	int err, results_map_fd, sock_fd, duration = 0;

	struct sockaddr curr, orig, tmp;

	struct sockaddr_in *in = (struct sockaddr_in *)&curr;

	struct bpf_link *kprobe_link = NULL;

	struct bpf_program *kprobe_prog;

	struct bpf_object *obj;

	static const int zero = 0;

	obj = bpf_object__open_file(obj_file, &opts);

	if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj)))

		return;

	kprobe_prog = bpf_object__find_program_by_title(obj, prog_name);

	if (CHECK(!kprobe_prog, "find_probe",

		  "prog '%s' not found\n", prog_name))

		goto cleanup;

	err = bpf_object__load(obj);

	if (CHECK(err, "obj_load", "err %d\n", err))

		goto cleanup;

	results_map_fd = bpf_find_map(__func__, obj, "test_pro.bss");

	if (CHECK(results_map_fd < 0, "find_bss_map",

		  "err %d\n", results_map_fd))

		goto cleanup;

	kprobe_link = bpf_program__attach_kprobe(kprobe_prog, false,

						 kprobe_name);

	if (CHECK(IS_ERR(kprobe_link), "attach_kprobe",

		  "err %ld\n", PTR_ERR(kprobe_link))) {

		kprobe_link = NULL;

		goto cleanup;

	}

	memset(&curr, 0, sizeof(curr));

	in->sin_family = AF_INET;

	in->sin_port = htons(5555);

	in->sin_addr.s_addr = inet_addr("255.255.255.255");

	memcpy(&orig, &curr, sizeof(curr));

	sock_fd = socket(AF_INET, SOCK_STREAM, 0);

	if (CHECK(sock_fd < 0, "create_sock_fd", "err %d\n", sock_fd))

		goto cleanup;

	connect(sock_fd, &curr, sizeof(curr));

	close(sock_fd);

	err = bpf_map_lookup_elem(results_map_fd, &zero, &tmp);

	if (CHECK(err, "get_kprobe_res",

		  "failed to get kprobe res: %d\n", err))

		goto cleanup;

	in = (struct sockaddr_in *)&tmp;

	if (CHECK(memcmp(&tmp, &orig, sizeof(orig)), "check_kprobe_res",

		  "wrong kprobe res from probe read: %s:%u\n",

		  inet_ntoa(in->sin_addr), ntohs(in->sin_port)))

		goto cleanup;

	memset(&tmp, 0xab, sizeof(tmp));

	in = (struct sockaddr_in *)&curr;

	if (CHECK(memcmp(&curr, &tmp, sizeof(tmp)), "check_kprobe_res",

		  "wrong kprobe res from probe write: %s:%u\n",

		  inet_ntoa(in->sin_addr), ntohs(in->sin_port)))

		goto cleanup;

cleanup:

	bpf_link__destroy(kprobe_link);

	bpf_object__close(obj);

}

// SPDX-License-Identifier: GPL-2.0

#include <linux/ptrace.h>

#include <linux/bpf.h>

#include <netinet/in.h>

#include "bpf_helpers.h"

#include "bpf_tracing.h"

static struct sockaddr_in old;

SEC("kprobe/__sys_connect")

int handle_sys_connect(struct pt_regs *ctx)

{

	void *ptr = (void *)PT_REGS_PARM2(ctx);

	struct sockaddr_in new;

	bpf_probe_read_user(&old, sizeof(old), ptr);

	__builtin_memset(&new, 0xab, sizeof(new));

	bpf_probe_write_user(ptr, &new, sizeof(new));

	return 0;

}

char _license[] SEC("license") = "GPL";