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From: Lorenz Bauer <lmb@cloudflare.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	Marek Majkowski <marek@cloudflare.com>,
	David Miller <davem@davemloft.net>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	kernel-team <kernel-team@cloudflare.com>
Subject: Re: [PATCH bpf-next 2/9] xdp: Add new xdp_chain_map type for specifying XDP call sequences
Date: Wed, 2 Oct 2019 16:50:45 +0100	[thread overview]
Message-ID: <CACAyw9-u7oAmC1F4rW8wH2a2aoxrDHCENcM4j5WmriS7YLmevQ@mail.gmail.com> (raw)
In-Reply-To: <157002302672.1302756.10579143571088111093.stgit@alrua-x1>

On Wed, 2 Oct 2019 at 14:30, Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index 113e1286e184..ab855095c830 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -1510,3 +1510,156 @@ const struct bpf_map_ops htab_of_maps_map_ops = {
>         .map_gen_lookup = htab_of_map_gen_lookup,
>         .map_check_btf = map_check_no_btf,
>  };
> +
> +struct xdp_chain_table {
> +       struct bpf_prog *wildcard_act;
> +       struct bpf_prog *act[XDP_ACT_MAX];
> +};
> +
> +static int xdp_chain_map_alloc_check(union bpf_attr *attr)
> +{
> +       BUILD_BUG_ON(sizeof(struct xdp_chain_table) / sizeof(void *) !=
> +                    sizeof(struct xdp_chain_acts) / sizeof(u32));
> +
> +       if (attr->key_size != sizeof(u32) ||
> +           attr->value_size != sizeof(struct xdp_chain_acts))
> +               return -EINVAL;

How are we going to extend xdp_chain_acts if a new XDP action is introduced?

> +
> +       attr->value_size = sizeof(struct xdp_chain_table);
> +       return htab_map_alloc_check(attr);
> +}
> +
> +struct bpf_prog *bpf_xdp_chain_map_get_prog(struct bpf_map *map,
> +                                           u32 prev_id,
> +                                           enum xdp_action action)
> +{
> +       struct xdp_chain_table *tab;
> +       void *ptr;
> +
> +       ptr = htab_map_lookup_elem(map, &prev_id);
> +
> +       if (!ptr)
> +               return NULL;
> +
> +       tab = READ_ONCE(ptr);
> +       return tab->act[action - 1] ?: tab->wildcard_act;
> +}
> +EXPORT_SYMBOL_GPL(bpf_xdp_chain_map_get_prog);
> +
> +/* only called from syscall */
> +int bpf_xdp_chain_map_lookup_elem(struct bpf_map *map, void *key, void *value)
> +{
> +       struct xdp_chain_acts *act = value;
> +       struct xdp_chain_table *tab;
> +       void *ptr;
> +       u32 *cur;
> +       int i;
> +
> +       ptr = htab_map_lookup_elem(map, key);
> +       if (!ptr)
> +               return -ENOENT;
> +
> +       tab = READ_ONCE(ptr);
> +
> +       if (tab->wildcard_act)
> +               act->wildcard_act = tab->wildcard_act->aux->id;
> +
> +       cur = &act->drop_act;
> +       for (i = 0; i < XDP_ACT_MAX; i++, cur++)
> +               if(tab->act[i])
> +                       *cur = tab->act[i]->aux->id;

For completeness, zero out *cur in the else case?

> +
> +       return 0;
> +}
> +
> +static void *xdp_chain_map_get_ptr(int fd)
> +{
> +       struct bpf_prog *prog = bpf_prog_get(fd);
> +
> +       if (IS_ERR(prog))
> +               return prog;
> +
> +       if (prog->type != BPF_PROG_TYPE_XDP ||
> +           bpf_prog_is_dev_bound(prog->aux)) {
> +               bpf_prog_put(prog);
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       return prog;
> +}
> +
> +static void xdp_chain_map_put_ptrs(void *value)
> +{
> +       struct xdp_chain_table *tab = value;
> +       int i;
> +
> +       for (i = 0; i < XDP_ACT_MAX; i++)
> +               if (tab->act[i])
> +                       bpf_prog_put(tab->act[i]);
> +
> +       if (tab->wildcard_act)
> +               bpf_prog_put(tab->wildcard_act);
> +}
> +
> +/* only called from syscall */
> +int bpf_xdp_chain_map_update_elem(struct bpf_map *map, void *key, void *value,
> +                                 u64 map_flags)

Nit: check that map_flags == 0

> +{
> +       struct xdp_chain_acts *act = value;
> +       struct xdp_chain_table tab = {};
> +       u32 lookup_key = *((u32*)key);
> +       u32 *cur = &act->drop_act;
> +       bool found_val = false;
> +       int ret, i;
> +       void *ptr;
> +
> +       if (!lookup_key)
> +               return -EINVAL;

Is it possible to check that this is a valid prog id / fd or whatever it is?

> +
> +       if (act->wildcard_act) {

If this is an fd, 0 is a valid value no?

> +               ptr = xdp_chain_map_get_ptr(act->wildcard_act);
> +               if (IS_ERR(ptr))
> +                       return PTR_ERR(ptr);
> +               tab.wildcard_act = ptr;
> +               found_val = true;
> +       }
> +
> +       for (i = 0; i < XDP_ACT_MAX; i++, cur++) {
> +               if (*cur) {
> +                       ptr = xdp_chain_map_get_ptr(*cur);
> +                       if (IS_ERR(ptr)) {
> +                               ret = PTR_ERR(ptr);
> +                               goto out_err;
> +                       }
> +                       tab.act[i] = ptr;
> +                       found_val = true;
> +               }
> +       }
> +
> +       if (!found_val) {
> +               ret = -EINVAL;
> +               goto out_err;
> +       }
> +
> +       ret = htab_map_update_elem(map, key, &tab, map_flags);
> +       if (ret)
> +               goto out_err;
> +
> +       return ret;
> +
> +out_err:
> +       xdp_chain_map_put_ptrs(&tab);
> +
> +       return ret;
> +}
> +
> +
> +const struct bpf_map_ops xdp_chain_map_ops = {
> +       .map_alloc_check = xdp_chain_map_alloc_check,
> +       .map_alloc = htab_map_alloc,
> +       .map_free = fd_htab_map_free,
> +       .map_get_next_key = htab_map_get_next_key,
> +       .map_delete_elem = htab_map_delete_elem,
> +       .map_fd_put_value = xdp_chain_map_put_ptrs,
> +       .map_check_btf = map_check_no_btf,
> +};

--
Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

www.cloudflare.com

  reply	other threads:[~2019-10-02 15:50 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-02 13:30 [PATCH bpf-next 0/9] xdp: Support multiple programs on a single interface through chain calls Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 1/9] hashtab: Add new bpf_map_fd_put_value op Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 2/9] xdp: Add new xdp_chain_map type for specifying XDP call sequences Toke Høiland-Jørgensen
2019-10-02 15:50   ` Lorenz Bauer [this message]
2019-10-02 18:25     ` Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 3/9] xdp: Support setting and getting device chain map Toke Høiland-Jørgensen
2019-10-02 15:50   ` Lorenz Bauer
2019-10-02 18:32     ` Toke Høiland-Jørgensen
2019-10-02 18:07   ` kbuild test robot
2019-10-02 18:29   ` kbuild test robot
2019-10-02 13:30 ` [PATCH bpf-next 4/9] xdp: Implement chain call logic to support multiple programs on one interface Toke Høiland-Jørgensen
2019-10-02 17:33   ` kbuild test robot
2019-10-02 17:53   ` kbuild test robot
2019-10-02 13:30 ` [PATCH bpf-next 5/9] tools/include/uapi: Add XDP chain map definitions Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 6/9] tools/libbpf_probes: Add support for xdp_chain map type Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 7/9] bpftool: Add definitions " Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 8/9] libbpf: Add support for setting and getting XDP chain maps Toke Høiland-Jørgensen
2019-10-02 13:30 ` [PATCH bpf-next 9/9] selftests: Add tests for XDP chain calls Toke Høiland-Jørgensen
2019-10-02 15:10 ` [PATCH bpf-next 0/9] xdp: Support multiple programs on a single interface through " Alan Maguire
2019-10-02 15:33   ` Toke Høiland-Jørgensen
2019-10-02 16:34     ` John Fastabend
2019-10-02 18:33       ` Toke Høiland-Jørgensen
2019-10-02 20:34         ` John Fastabend
2019-10-03  7:48           ` Toke Høiland-Jørgensen
2019-10-03 10:09             ` Jesper Dangaard Brouer
2019-10-03 19:45               ` John Fastabend
2019-10-02 16:35 ` Lorenz Bauer
2019-10-02 18:54   ` Toke Høiland-Jørgensen
2019-10-02 16:43 ` John Fastabend
2019-10-02 19:09   ` Toke Høiland-Jørgensen
2019-10-02 19:15   ` Daniel Borkmann
2019-10-02 19:29     ` Toke Høiland-Jørgensen
2019-10-02 19:46     ` Alexei Starovoitov
2019-10-03  7:58       ` Toke Høiland-Jørgensen
2019-10-02 18:38 ` Song Liu
2019-10-02 18:54   ` Song Liu
2019-10-02 19:25     ` Toke Høiland-Jørgensen
2019-10-03  8:53       ` Jesper Dangaard Brouer
2019-10-03 14:03         ` Alexei Starovoitov
2019-10-03 14:33           ` Toke Høiland-Jørgensen
2019-10-03 14:53             ` Edward Cree
2019-10-03 18:49               ` Jesper Dangaard Brouer
2019-10-03 19:35               ` John Fastabend
2019-10-04  8:09                 ` Toke Høiland-Jørgensen
2019-10-04 10:34                   ` Edward Cree
2019-10-04 15:58                     ` Lorenz Bauer
2019-10-07 16:43                       ` Edward Cree
2019-10-07 17:12                         ` Lorenz Bauer
2019-10-07 19:21                           ` Edward Cree
2019-10-07 21:01                         ` Alexei Starovoitov
2019-10-02 19:23   ` Toke Høiland-Jørgensen
2019-10-02 19:49     ` Song Liu
2019-10-03  7:59       ` Toke Høiland-Jørgensen

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