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libbpf: Add support for BPF XDP link

Sync UAPI header and add support for using bpf_link-based XDP attachment.
Make xdp/ prog type set expected attach type. Kernel didn't enforce
attach_type for XDP programs before, so there is no backwards compatiblity
issues there.

Also fix section_names selftest to recognize that xdp prog types now have
expected attach type.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-8-andriin@fb.com
master
Andrii Nakryiko 1 year ago
committed by Andrii Nakryiko
parent
commit
a290d45322
  1. 10
      include/uapi/linux/bpf.h
  2. 9
      src/libbpf.c
  3. 2
      src/libbpf.h
  4. 1
      src/libbpf.map

10
include/uapi/linux/bpf.h

@ -230,6 +230,7 @@ enum bpf_attach_type {
BPF_CGROUP_INET_SOCK_RELEASE,
BPF_XDP_CPUMAP,
BPF_SK_LOOKUP,
BPF_XDP,
__MAX_BPF_ATTACH_TYPE
};
@ -242,6 +243,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_CGROUP = 3,
BPF_LINK_TYPE_ITER = 4,
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
MAX_BPF_LINK_TYPE,
};
@ -614,7 +616,10 @@ union bpf_attr {
struct { /* struct used by BPF_LINK_CREATE command */
__u32 prog_fd; /* eBPF program to attach */
__u32 target_fd; /* object to attach to */
union {
__u32 target_fd; /* object to attach to */
__u32 target_ifindex; /* target ifindex */
};
__u32 attach_type; /* attach type */
__u32 flags; /* extra flags */
} link_create;
@ -4064,6 +4069,9 @@ struct bpf_link_info {
__u32 netns_ino;
__u32 attach_type;
} netns;
struct {
__u32 ifindex;
} xdp;
};
} __attribute__((aligned(8)));

9
src/libbpf.c

@ -6915,7 +6915,8 @@ static const struct bpf_sec_def section_defs[] = {
BPF_XDP_DEVMAP),
BPF_EAPROG_SEC("xdp_cpumap/", BPF_PROG_TYPE_XDP,
BPF_XDP_CPUMAP),
BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
BPF_EAPROG_SEC("xdp", BPF_PROG_TYPE_XDP,
BPF_XDP),
BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
BPF_PROG_SEC("lwt_out", BPF_PROG_TYPE_LWT_OUT),
@ -8281,6 +8282,12 @@ bpf_program__attach_netns(struct bpf_program *prog, int netns_fd)
return bpf_program__attach_fd(prog, netns_fd, "netns");
}
struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex)
{
/* target_fd/target_ifindex use the same field in LINK_CREATE */
return bpf_program__attach_fd(prog, ifindex, "xdp");
}
struct bpf_link *
bpf_program__attach_iter(struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts)

2
src/libbpf.h

@ -257,6 +257,8 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd);
LIBBPF_API struct bpf_link *
bpf_program__attach_netns(struct bpf_program *prog, int netns_fd);
LIBBPF_API struct bpf_link *
bpf_program__attach_xdp(struct bpf_program *prog, int ifindex);
struct bpf_map;

1
src/libbpf.map

@ -286,6 +286,7 @@ LIBBPF_0.1.0 {
bpf_map__set_value_size;
bpf_map__type;
bpf_map__value_size;
bpf_program__attach_xdp;
bpf_program__autoload;
bpf_program__is_sk_lookup;
bpf_program__set_autoload;

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