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Message-ID: <d7b7354d-a802-c711-f66f-118986652a8e@intel.com>
Date: Fri, 5 Mar 2021 18:11:33 +0100
From: Björn Töpel <bjorn.topel@...el.com>
To: Daniel Borkmann <daniel@...earbox.net>,
Björn Töpel <bjorn.topel@...il.com>,
ast@...nel.org, netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: 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 2021-03-05 16:55, Daniel Borkmann wrote:
> 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.
>
ACK!
>> + 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.
>
Ok!
>> 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.
>
Fair enough; I guess my love for the 100 chars lines is bigger than
conformity. :-P
>> + 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]);'
>
Indeed.
I'll make sure to include the fixups in v6.
Björn
>> + 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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