KFunc `bpf_sock_addr_set_sun_path`

v6.7

Modify the sockaddr of a socket.

Definition

int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern, const u8 *sun_path, u32 sun_path__sz)

Usage

Docs could be improved

This part of the docs is incomplete, contributions are very welcome

Program types

The following program types can make use of this kfunc:

Example

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#include "vmlinux.h"

#include <string.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>
#include "bpf_kfuncs.h"

__u8 SERVUN_REWRITE_ADDRESS[] = "\0bpf_cgroup_unix_test_rewrite";

SEC("cgroup/connect_unix")
int connect_unix_prog(struct bpf_sock_addr *ctx)
{
    struct bpf_sock_addr_kern *sa_kern = bpf_cast_to_kern_ctx(ctx);
    struct sockaddr_un *sa_kern_unaddr;
    __u32 unaddrlen = offsetof(struct sockaddr_un, sun_path) +
              sizeof(SERVUN_REWRITE_ADDRESS) - 1;
    int ret;

    /* Rewrite destination. */
    ret = bpf_sock_addr_set_sun_path(sa_kern, SERVUN_REWRITE_ADDRESS,
                     sizeof(SERVUN_REWRITE_ADDRESS) - 1);
    if (ret)
        return 0;

    if (sa_kern->uaddrlen != unaddrlen)
        return 0;

    sa_kern_unaddr = bpf_rdonly_cast(sa_kern->uaddr,
                        bpf_core_type_id_kernel(struct sockaddr_un));
    if (memcmp(sa_kern_unaddr->sun_path, SERVUN_REWRITE_ADDRESS,
            sizeof(SERVUN_REWRITE_ADDRESS) - 1) != 0)
        return 0;

    return 1;
}

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

KFunc bpf_sock_addr_set_sun_path