From: Jakub Sitnicki <jakub@cloudflare•com>
To: Andrii Nakryiko <andrii.nakryiko@gmail•com>
Cc: bpf <bpf@vger•kernel.org>, Networking <netdev@vger•kernel.org>,
kernel-team <kernel-team@cloudflare•com>,
Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
"David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>
Subject: Re: [PATCH bpf-next v3 01/16] bpf, netns: Handle multiple link attachments
Date: Thu, 09 Jul 2020 14:49:46 +0200 [thread overview]
Message-ID: <87k0zcam51.fsf@cloudflare.com> (raw)
In-Reply-To: <CAEf4Bzby9pxaaadTAfuvBER1UnaksS3ajpE6SB79L+g3j_YdAg@mail.gmail.com>
On Thu, Jul 09, 2020 at 05:44 AM CEST, Andrii Nakryiko wrote:
> On Thu, Jul 2, 2020 at 2:24 AM Jakub Sitnicki <jakub@cloudflare•com> wrote:
>>
>> Extend the BPF netns link callbacks to rebuild (grow/shrink) or update the
>> prog_array at given position when link gets attached/updated/released.
>>
>> This let's us lift the limit of having just one link attached for the new
>> attach type introduced by subsequent patch.
>>
>> No functional changes intended.
>>
>> Signed-off-by: Jakub Sitnicki <jakub@cloudflare•com>
>> ---
>>
>> Notes:
>> v3:
>> - New in v3 to support multi-prog attachments. (Alexei)
>>
>> include/linux/bpf.h | 4 ++
>> kernel/bpf/core.c | 22 ++++++++++
>> kernel/bpf/net_namespace.c | 88 +++++++++++++++++++++++++++++++++++---
>> 3 files changed, 107 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 3d2ade703a35..26bc70533db0 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -928,6 +928,10 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array *progs,
>>
>> void bpf_prog_array_delete_safe(struct bpf_prog_array *progs,
>> struct bpf_prog *old_prog);
>> +void bpf_prog_array_delete_safe_at(struct bpf_prog_array *array,
>> + unsigned int index);
>> +void bpf_prog_array_update_at(struct bpf_prog_array *array, unsigned int index,
>> + struct bpf_prog *prog);
>> int bpf_prog_array_copy_info(struct bpf_prog_array *array,
>> u32 *prog_ids, u32 request_cnt,
>> u32 *prog_cnt);
>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
>> index 9df4cc9a2907..d4b3b9ee6bf1 100644
>> --- a/kernel/bpf/core.c
>> +++ b/kernel/bpf/core.c
>> @@ -1958,6 +1958,28 @@ void bpf_prog_array_delete_safe(struct bpf_prog_array *array,
>> }
>> }
>>
>> +void bpf_prog_array_delete_safe_at(struct bpf_prog_array *array,
>> + unsigned int index)
>> +{
>> + bpf_prog_array_update_at(array, index, &dummy_bpf_prog.prog);
>> +}
>> +
>> +void bpf_prog_array_update_at(struct bpf_prog_array *array, unsigned int index,
>> + struct bpf_prog *prog)
>
> it's a good idea to mention it in a comment for both delete_safe_at
> and update_at that slots with dummy entries are ignored.
I agree. These two need doc comments. update_at doesn't event hint that
this is not a regular update operation. Will add in v4.
>
> Also, given that index can be out of bounds, should these functions
> actually return error if the slot is not found?
That won't hurt. I mean, from bpf-netns PoV getting such an error would
indicate that there is a bug in the code that manages prog_array. But
perhaps other future users of this new prog_array API can benefit.
>
>> +{
>> + struct bpf_prog_array_item *item;
>> +
>> + for (item = array->items; item->prog; item++) {
>> + if (item->prog == &dummy_bpf_prog.prog)
>> + continue;
>> + if (!index) {
>> + WRITE_ONCE(item->prog, prog);
>> + break;
>> + }
>> + index--;
>> + }
>> +}
>> +
>> int bpf_prog_array_copy(struct bpf_prog_array *old_array,
>> struct bpf_prog *exclude_prog,
>> struct bpf_prog *include_prog,
>> diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
>> index 247543380fa6..6011122c35b6 100644
>> --- a/kernel/bpf/net_namespace.c
>> +++ b/kernel/bpf/net_namespace.c
>> @@ -36,11 +36,51 @@ static void netns_bpf_run_array_detach(struct net *net,
>> bpf_prog_array_free(run_array);
>> }
>>
>> +static unsigned int link_index(struct net *net,
>> + enum netns_bpf_attach_type type,
>> + struct bpf_netns_link *link)
>> +{
>> + struct bpf_netns_link *pos;
>> + unsigned int i = 0;
>> +
>> + list_for_each_entry(pos, &net->bpf.links[type], node) {
>> + if (pos == link)
>> + return i;
>> + i++;
>> + }
>> + return UINT_MAX;
>
> Why not return a negative error, if the slot is not found? Feels a bit
> unusual as far as error reporting goes.
Returning uint played well with the consumer of link_index() return
value, that is bpf_prog_array_update_at(). update at takes an index into
the array, which must not be negative.
But I don't have strong feelings toward it. Will switch to -ENOENT in
v4.
>
>> +}
>> +
>
> [...]
next prev parent reply other threads:[~2020-07-09 12:49 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 9:24 [PATCH bpf-next v3 00/16] Run a BPF program on socket lookup Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 01/16] bpf, netns: Handle multiple link attachments Jakub Sitnicki
2020-07-09 3:44 ` Andrii Nakryiko
2020-07-09 12:49 ` Jakub Sitnicki [this message]
2020-07-09 22:02 ` Andrii Nakryiko
2020-07-10 19:23 ` Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 02/16] bpf: Introduce SK_LOOKUP program type with a dedicated attach point Jakub Sitnicki
2020-07-04 18:42 ` Yonghong Song
2020-07-06 11:44 ` Jakub Sitnicki
2020-07-05 9:20 ` kernel test robot
2020-07-05 9:20 ` [RFC PATCH] bpf: sk_lookup_prog_ops can be static kernel test robot
2020-07-07 9:21 ` [PATCH bpf-next v3 02/16] bpf: Introduce SK_LOOKUP program type with a dedicated attach point Jakub Sitnicki
2020-07-09 4:08 ` Andrii Nakryiko
2020-07-09 13:25 ` Jakub Sitnicki
2020-07-09 23:09 ` Andrii Nakryiko
2020-07-10 8:55 ` Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 03/16] inet: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 04/16] inet: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-02 10:27 ` Lorenz Bauer
2020-07-02 12:46 ` Jakub Sitnicki
2020-07-02 13:19 ` Lorenz Bauer
2020-07-06 11:24 ` Jakub Sitnicki
2020-07-06 12:06 ` Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 05/16] inet6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 06/16] inet6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 07/16] udp: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 08/16] udp: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 09/16] udp6: Extract helper for selecting socket from reuseport group Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 10/16] udp6: Run SK_LOOKUP BPF program on socket lookup Jakub Sitnicki
2020-07-02 14:51 ` kernel test robot
2020-07-03 13:04 ` Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 11/16] bpf: Sync linux/bpf.h to tools/ Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 12/16] libbpf: Add support for SK_LOOKUP program type Jakub Sitnicki
2020-07-09 4:23 ` Andrii Nakryiko
2020-07-09 15:51 ` Jakub Sitnicki
2020-07-09 23:13 ` Andrii Nakryiko
2020-07-10 8:37 ` Jakub Sitnicki
2020-07-10 18:55 ` Andrii Nakryiko
2020-07-10 19:24 ` Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 13/16] tools/bpftool: Add name mappings for SK_LOOKUP prog and attach type Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 14/16] selftests/bpf: Add verifier tests for bpf_sk_lookup context access Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 15/16] selftests/bpf: Rename test_sk_lookup_kern.c to test_ref_track_kern.c Jakub Sitnicki
2020-07-02 9:24 ` [PATCH bpf-next v3 16/16] selftests/bpf: Tests for BPF_SK_LOOKUP attach point Jakub Sitnicki
2020-07-02 11:01 ` Lorenz Bauer
2020-07-02 12:59 ` Jakub Sitnicki
2020-07-09 4:28 ` Andrii Nakryiko
2020-07-09 15:54 ` Jakub Sitnicki
2020-07-02 11:05 ` [PATCH bpf-next v3 00/16] Run a BPF program on socket lookup Lorenz Bauer
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