Libbpf userspace function `bpf_link_create`

0.0.8

Low level wrapper around the BPF_LINK_CREATE syscall command.

Definition

int bpf_link_create(int prog_fd, int target_fd, enum bpf_attach_type attach_type, const struct bpf_link_create_opts *opts);

Parameters

prog_fd: file descriptor of the program to attach
target_fd: file descriptor of the target object
attach_type: type of the attachment
opts: options for configuring the attachment

Return

>0, file descriptor of the created link; negative error code, otherwise

`struct bpf_link_create_opts`

struct bpf_link_create_opts {
    size_t sz; /* size of this struct for forward/backward compatibility */
    __u32 flags;
    union bpf_iter_link_info *iter_info;
    __u32 iter_info_len;
    __u32 target_btf_id;
    union {
        struct {
            __u64 bpf_cookie;
        } perf_event;
        struct {
            __u32 flags;
            __u32 cnt;
            const char **syms;
            const unsigned long *addrs;
            const __u64 *cookies;
        } kprobe_multi;
        struct {
            __u32 flags;
            __u32 cnt;
            const char *path;
            const unsigned long *offsets;
            const unsigned long *ref_ctr_offsets;
            const __u64 *cookies;
            __u32 pid;
        } uprobe_multi;
        struct {
            __u64 cookie;
        } tracing;
        struct {
            __u32 pf;
            __u32 hooknum;
            __s32 priority;
            __u32 flags;
        } netfilter;
        struct {
            __u32 relative_fd;
            __u32 relative_id;
            __u64 expected_revision;
        } tcx;
        struct {
            __u32 relative_fd;
            __u32 relative_id;
            __u64 expected_revision;
        } netkit;
    };
    size_t :0;
};

Usage

This function should only be used for specific program types that need to be attached via the BPF_LINK_CREATE syscall command and you need specific control over this process. In most cases, the bpf_program__attach or specific bpf_program__attach_* functions should be used instead.

Example

Docs could be improved

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

Libbpf userspace function bpf_link_create