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Message-ID: <c4273132-6ce3-f7b4-6312-4dce18a5ebc8@fb.com>
Date: Sat, 5 Jun 2021 10:09:59 -0700
From: Yonghong Song <yhs@...com>
To: Kumar Kartikeya Dwivedi <memxor@...il.com>, <bpf@...r.kernel.org>
CC: Toke Høiland-Jørgensen <toke@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Vlad Buslov <vladbu@...dia.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jesper Dangaard Brouer <brouer@...hat.com>,
<netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v2 6/7] libbpf: add bpf_link based TC-BPF
management API
On 6/3/21 11:31 PM, Kumar Kartikeya Dwivedi wrote:
> This adds userspace TC-BPF management API based on bpf_link.
>
> Reviewed-by: Toke Høiland-Jørgensen <toke@...hat.com>.
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
> ---
> tools/lib/bpf/bpf.c | 8 +++++-
> tools/lib/bpf/bpf.h | 8 +++++-
> tools/lib/bpf/libbpf.c | 59 ++++++++++++++++++++++++++++++++++++++--
> tools/lib/bpf/libbpf.h | 17 ++++++++++++
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/netlink.c | 5 ++--
> tools/lib/bpf/netlink.h | 8 ++++++
> 7 files changed, 100 insertions(+), 6 deletions(-)
> create mode 100644 tools/lib/bpf/netlink.h
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 86dcac44f32f..bebccea9bfd7 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -28,6 +28,7 @@
> #include <asm/unistd.h>
> #include <errno.h>
> #include <linux/bpf.h>
> +#include <arpa/inet.h>
> #include "bpf.h"
> #include "libbpf.h"
> #include "libbpf_internal.h"
> @@ -693,7 +694,12 @@ int bpf_link_create(int prog_fd, int target_fd,
> attr.link_create.attach_type = attach_type;
> attr.link_create.flags = OPTS_GET(opts, flags, 0);
>
> - if (iter_info_len) {
> + if (attach_type == BPF_TC) {
> + attr.link_create.tc.parent = OPTS_GET(opts, tc.parent, 0);
> + attr.link_create.tc.handle = OPTS_GET(opts, tc.handle, 0);
> + attr.link_create.tc.priority = OPTS_GET(opts, tc.priority, 0);
> + attr.link_create.tc.gen_flags = OPTS_GET(opts, tc.gen_flags, 0);
> + } else if (iter_info_len) {
> attr.link_create.iter_info =
> ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));
> attr.link_create.iter_info_len = iter_info_len;
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 4f758f8f50cd..f2178309e9ea 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -177,8 +177,14 @@ struct bpf_link_create_opts {
> union bpf_iter_link_info *iter_info;
> __u32 iter_info_len;
> __u32 target_btf_id;
> + struct {
> + __u32 parent;
> + __u32 handle;
> + __u32 priority;
> + __u32 gen_flags;
> + } tc;
> };
> -#define bpf_link_create_opts__last_field target_btf_id
> +#define bpf_link_create_opts__last_field tc.gen_flags
>
> LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
> enum bpf_attach_type attach_type,
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 1c4e20e75237..7809536980b1 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -55,6 +55,7 @@
> #include "libbpf_internal.h"
> #include "hashmap.h"
> #include "bpf_gen_internal.h"
> +#include "netlink.h"
>
> #ifndef BPF_FS_MAGIC
> #define BPF_FS_MAGIC 0xcafe4a11
> @@ -7185,7 +7186,7 @@ static int bpf_object__collect_relos(struct bpf_object *obj)
>
> for (i = 0; i < obj->nr_programs; i++) {
> struct bpf_program *p = &obj->programs[i];
> -
> +
> if (!p->nr_reloc)
> continue;
>
> @@ -10005,7 +10006,7 @@ struct bpf_link {
> int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
> {
> int ret;
> -
> +
> ret = bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
> return libbpf_err_errno(ret);
> }
> @@ -10613,6 +10614,60 @@ struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex)
> return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
> }
>
> +struct bpf_link *bpf_program__attach_tc(struct bpf_program *prog,
> + const struct bpf_tc_hook *hook,
> + const struct bpf_tc_link_opts *opts)
> +{
> + DECLARE_LIBBPF_OPTS(bpf_link_create_opts, lopts, 0);
> + char errmsg[STRERR_BUFSIZE];
> + int prog_fd, link_fd, ret;
> + struct bpf_link *link;
> + __u32 parent;
> +
> + if (!hook || !OPTS_VALID(hook, bpf_tc_hook) ||
> + !OPTS_VALID(opts, bpf_tc_link_opts))
> + return ERR_PTR(-EINVAL);
For libbpf API functions, the libbpf proposed 1.0 change
https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
will return NULL and set errno properly.
So the above code probably should be
return errno = EINVAL, NULL;
> +
> + if (OPTS_GET(hook, ifindex, 0) <= 0 ||
> + OPTS_GET(opts, priority, 0) > UINT16_MAX)
> + return ERR_PTR(-EINVAL);
> +
> + parent = OPTS_GET(hook, parent, 0);
> +
> + ret = tc_get_tcm_parent(OPTS_GET(hook, attach_point, 0),
> + &parent);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + lopts.tc.parent = parent;
> + lopts.tc.handle = OPTS_GET(opts, handle, 0);
> + lopts.tc.priority = OPTS_GET(opts, priority, 0);
> + lopts.tc.gen_flags = OPTS_GET(opts, gen_flags, 0);
> +
> + prog_fd = bpf_program__fd(prog);
> + if (prog_fd < 0) {
> + pr_warn("prog '%s': can't attach before loaded\n", prog->name);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + link = calloc(1, sizeof(*link));
> + if (!link)
> + return ERR_PTR(-ENOMEM);
> + link->detach = &bpf_link__detach_fd;
> +
> + link_fd = bpf_link_create(prog_fd, OPTS_GET(hook, ifindex, 0), BPF_TC, &lopts);
> + if (link_fd < 0) {
> + link_fd = -errno;
> + free(link);
> + pr_warn("prog '%s': failed to attach tc filter: %s\n",
> + prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
> + return ERR_PTR(link_fd);
> + }
> + link->fd = link_fd;
> +
> + return link;
> +}
> +
[...]
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