1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
 3
 4#include "vmlinux.h"
 5
 6#include <string.h>
 7#include <bpf/bpf_helpers.h>
 8#include <bpf/bpf_core_read.h>
 9#include "bpf_kfuncs.h"
10
11__u8 SERVUN_REWRITE_ADDRESS[] = "\0bpf_cgroup_unix_test_rewrite";
12
13SEC("cgroup/sendmsg_unix")
14int sendmsg_unix_prog(struct bpf_sock_addr *ctx)
15{
16	struct bpf_sock_addr_kern *sa_kern = bpf_cast_to_kern_ctx(ctx);
17	struct sockaddr_un *sa_kern_unaddr;
18	__u32 unaddrlen = offsetof(struct sockaddr_un, sun_path) +
19			  sizeof(SERVUN_REWRITE_ADDRESS) - 1;
20	int ret;
21
22	/* Rewrite destination. */
23	ret = bpf_sock_addr_set_sun_path(sa_kern, SERVUN_REWRITE_ADDRESS,
24					 sizeof(SERVUN_REWRITE_ADDRESS) - 1);
25	if (ret)
26		return 0;
27
28	if (sa_kern->uaddrlen != unaddrlen)
29		return 0;
30
31	sa_kern_unaddr = bpf_rdonly_cast(sa_kern->uaddr,
32						bpf_core_type_id_kernel(struct sockaddr_un));
33	if (memcmp(sa_kern_unaddr->sun_path, SERVUN_REWRITE_ADDRESS,
34			sizeof(SERVUN_REWRITE_ADDRESS) - 1) != 0)
35		return 0;
36
37	return 1;
38}
39
40char _license[] SEC("license") = "GPL";