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libbpf: Add netfilter link attach helper

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Add new api function: bpf_program__attach_netfilter.

It takes a bpf program (netfilter type), and a pointer to a option struct
that contains the desired attachment (protocol family, priority, hook
location, ...).

It returns a pointer to a 'bpf_link' structure or NULL on error.

Next patch adds new netfilter_basic test that uses this function to
attach a program to a few pf/hook/priority combinations.

v2: change name and use bpf_link_create.

Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/bpf/CAEf4BzZrmUv27AJp0dDxBDMY_B8e55-wLs8DUKK69vCWsCG_pQ@mail.gmail.com/
Link: https://lore.kernel.org/bpf/CAEf4BzZ69YgrQW7DHCJUT_X+GqMq_ZQQPBwopaJJVGFD5=d5Vg@mail.gmail.com/
Link: https://lore.kernel.org/bpf/20230628152738.22765-2-fw@strlen.de
This commit is contained in:
Florian Westphal
2023-06-28 17:27:37 +02:00
committed by Andrii Nakryiko
parent 3f33f9a6b8
commit 6bec18258c
5 changed files with 72 additions and 0 deletions
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42
src/libbpf.c
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@@ -11815,6 +11815,48 @@ static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_l
return libbpf_get_error(*link);
}
struct bpf_link *bpf_program__attach_netfilter(const struct bpf_program *prog,
const struct bpf_netfilter_opts *opts)
{
LIBBPF_OPTS(bpf_link_create_opts, lopts);
struct bpf_link *link;
int prog_fd, link_fd;
if (!OPTS_VALID(opts, bpf_netfilter_opts))
return libbpf_err_ptr(-EINVAL);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach before loaded\n", prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->detach = &bpf_link__detach_fd;
lopts.netfilter.pf = OPTS_GET(opts, pf, 0);
lopts.netfilter.hooknum = OPTS_GET(opts, hooknum, 0);
lopts.netfilter.priority = OPTS_GET(opts, priority, 0);
lopts.netfilter.flags = OPTS_GET(opts, flags, 0);
link_fd = bpf_link_create(prog_fd, 0, BPF_NETFILTER, &lopts);
if (link_fd < 0) {
char errmsg[STRERR_BUFSIZE];
link_fd = -errno;
free(link);
pr_warn("prog '%s': failed to attach to netfilter: %s\n",
prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(link_fd);
}
link->fd = link_fd;
return link;
}
struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
{
struct bpf_link *link = NULL;