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Message-ID: <eb40aa9a-ffd4-539a-8a4e-420160962500@iogearbox.net>
Date: Fri, 5 Mar 2021 16:55:02 +0100
From: Daniel Borkmann <daniel@...earbox.net>
To: Björn Töpel <bjorn.topel@...il.com>,
ast@...nel.org, netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: Björn Töpel <bjorn.topel@...el.com>,
maciej.fijalkowski@...el.com, hawk@...nel.org, toke@...hat.com,
magnus.karlsson@...el.com, john.fastabend@...il.com,
kuba@...nel.org, davem@...emloft.net,
Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: [PATCH bpf-next v5 1/2] bpf, xdp: make bpf_redirect_map() a map
operation
On 2/27/21 1:21 PM, Björn Töpel wrote:
[...]
Look good. Small nits inline I had originally fixed up locally before glancing at 2/2:
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 4c730863fa77..3d3e89a37e62 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -118,6 +118,9 @@ struct bpf_map_ops {
> void *owner, u32 size);
> struct bpf_local_storage __rcu ** (*map_owner_storage_ptr)(void *owner);
>
> + /* XDP helpers.*/
If this really needs a comment, I'd say 'Misc helpers' since we might later also
add implementations for tc and everything can be inferred from the code anyway.
> + int (*map_redirect)(struct bpf_map *map, u32 ifindex, u64 flags);
> +
[...]
> static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 9fe90ce52a65..b6c44b85e960 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -5582,7 +5582,8 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
> func_id != BPF_FUNC_map_push_elem &&
> func_id != BPF_FUNC_map_pop_elem &&
> func_id != BPF_FUNC_map_peek_elem &&
> - func_id != BPF_FUNC_for_each_map_elem)
> + func_id != BPF_FUNC_for_each_map_elem &&
> + func_id != BPF_FUNC_redirect_map)
> return 0;
>
> if (map == NULL) {
> @@ -12017,7 +12018,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> insn->imm == BPF_FUNC_map_delete_elem ||
> insn->imm == BPF_FUNC_map_push_elem ||
> insn->imm == BPF_FUNC_map_pop_elem ||
> - insn->imm == BPF_FUNC_map_peek_elem)) {
> + insn->imm == BPF_FUNC_map_peek_elem ||
> + insn->imm == BPF_FUNC_redirect_map)) {
> aux = &env->insn_aux_data[i + delta];
> if (bpf_map_ptr_poisoned(aux))
> goto patch_call_imm;
> @@ -12059,6 +12061,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> (int (*)(struct bpf_map *map, void *value))NULL));
> BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
> (int (*)(struct bpf_map *map, void *value))NULL));
> + BUILD_BUG_ON(!__same_type(ops->map_redirect,
> + (int (*)(struct bpf_map *map, u32 ifindex, u64 flags))NULL));
I added a linebreak here.
> patch_map_ops_generic:
> switch (insn->imm) {
> case BPF_FUNC_map_lookup_elem:
> @@ -12085,6 +12089,9 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
> __bpf_call_base;
> continue;
> + case BPF_FUNC_redirect_map:
> + insn->imm = BPF_CAST_CALL(ops->map_redirect) - __bpf_call_base;
Ditto so it matches the rest.
> + continue;
> }
>
> goto patch_call_imm;
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 13bcf248ee7b..960299a3744f 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -3934,22 +3934,6 @@ void xdp_do_flush(void)
> }
> EXPORT_SYMBOL_GPL(xdp_do_flush);
>
> -static inline void *__xdp_map_lookup_elem(struct bpf_map *map, u32 index)
> -{
> - switch (map->map_type) {
> - case BPF_MAP_TYPE_DEVMAP:
> - return __dev_map_lookup_elem(map, index);
> - case BPF_MAP_TYPE_DEVMAP_HASH:
> - return __dev_map_hash_lookup_elem(map, index);
> - case BPF_MAP_TYPE_CPUMAP:
> - return __cpu_map_lookup_elem(map, index);
> - case BPF_MAP_TYPE_XSKMAP:
> - return __xsk_map_lookup_elem(map, index);
> - default:
> - return NULL;
> - }
> -}
> -
> void bpf_clear_redirect_map(struct bpf_map *map)
> {
> struct bpf_redirect_info *ri;
> @@ -4103,28 +4087,7 @@ static const struct bpf_func_proto bpf_xdp_redirect_proto = {
> BPF_CALL_3(bpf_xdp_redirect_map, struct bpf_map *, map, u32, ifindex,
> u64, flags)
> {
> - struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
> -
> - /* Lower bits of the flags are used as return code on lookup failure */
> - if (unlikely(flags > XDP_TX))
> - return XDP_ABORTED;
> -
> - ri->tgt_value = __xdp_map_lookup_elem(map, ifindex);
> - if (unlikely(!ri->tgt_value)) {
> - /* If the lookup fails we want to clear out the state in the
> - * redirect_info struct completely, so that if an eBPF program
> - * performs multiple lookups, the last one always takes
> - * precedence.
> - */
> - WRITE_ONCE(ri->map, NULL);
> - return flags;
> - }
> -
> - ri->flags = flags;
> - ri->tgt_index = ifindex;
> - WRITE_ONCE(ri->map, map);
> -
> - return XDP_REDIRECT;
> + return map->ops->map_redirect(map, ifindex, flags);
> }
>
> static const struct bpf_func_proto bpf_xdp_redirect_map_proto = {
> diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c
> index 113fd9017203..711acb3636b3 100644
> --- a/net/xdp/xskmap.c
> +++ b/net/xdp/xskmap.c
> @@ -125,6 +125,18 @@ static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
> return insn - insn_buf;
> }
>
> +static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
> +{
> + struct xsk_map *m = container_of(map, struct xsk_map, map);
> + struct xdp_sock *xs;
> +
> + if (key >= map->max_entries)
> + return NULL;
> +
> + xs = READ_ONCE(m->xsk_map[key]);
Just 'return READ_ONCE(m->xsk_map[key]);'
> + return xs;
> +}
> +
> static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
> {
> WARN_ON_ONCE(!rcu_read_lock_held());
> @@ -215,6 +227,11 @@ static int xsk_map_delete_elem(struct bpf_map *map, void *key)
> return 0;
> }
>
> +static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
> +{
> + return __bpf_xdp_redirect_map(map, ifindex, flags, __xsk_map_lookup_elem);
> +}
> +
> void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
> struct xdp_sock **map_entry)
> {
> @@ -247,4 +264,5 @@ const struct bpf_map_ops xsk_map_ops = {
> .map_check_btf = map_check_no_btf,
> .map_btf_name = "xsk_map",
> .map_btf_id = &xsk_map_btf_id,
> + .map_redirect = xsk_map_redirect,
> };
>
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