From: Daniel Borkmann <daniel@iogearbox•net>
To: Jesper Dangaard Brouer <brouer@redhat•com>
Cc: Brenden Blanco <bblanco@plumgrid•com>,
davem@davemloft•net, netdev@vger•kernel.org, tom@herbertland•com,
alexei.starovoitov@gmail•com, gerlitz@mellanox•com,
john.fastabend@gmail•com
Subject: Re: [RFC PATCH 1/5] bpf: add PHYS_DEV prog type for early driver filter
Date: Mon, 04 Apr 2016 15:36:58 +0200 [thread overview]
Message-ID: <57026DFA.3090201@iogearbox.net> (raw)
In-Reply-To: <20160404150700.1456ae80@redhat.com>
On 04/04/2016 03:07 PM, Jesper Dangaard Brouer wrote:
> On Mon, 04 Apr 2016 10:49:09 +0200 Daniel Borkmann <daniel@iogearbox•net> wrote:
>> On 04/02/2016 03:21 AM, Brenden Blanco wrote:
>>> Add a new bpf prog type that is intended to run in early stages of the
>>> packet rx path. Only minimal packet metadata will be available, hence a new
>>> context type, struct xdp_metadata, is exposed to userspace. So far only
>>> expose the readable packet length, and only in read mode.
>>>
>>> The PHYS_DEV name is chosen to represent that the program is meant only
>>> for physical adapters, rather than all netdevs.
>>>
>>> While the user visible struct is new, the underlying context must be
>>> implemented as a minimal skb in order for the packet load_* instructions
>>> to work. The skb filled in by the driver must have skb->len, skb->head,
>>> and skb->data set, and skb->data_len == 0.
>>>
> [...]
>>
>> Do you plan to support bpf_skb_load_bytes() as well? I like using
>> this API especially when dealing with larger chunks (>4 bytes) to
>> load into stack memory, plus content is kept in network byte order.
>>
>> What about other helpers such as bpf_skb_store_bytes() et al that
>> work on skbs. Do you intent to reuse them as is and thus populate
>> the per cpu skb with needed fields (faking linear data), or do you
>> see larger obstacles that prevent for this?
>
> Argh... maybe the minimal pseudo/fake SKB is the wrong "signal" to send
> to users of this API.
>
> The hole idea is that an SKB is NOT allocated yet, and not needed at
> this level. If we start supporting calling underlying SKB functions,
> then we will end-up in the same place (performance wise).
I'm talking about the current skb-related BPF helper functions we have,
so the question is how much from that code we have we can reuse under
these constraints (obviously things like the tunnel helpers are a different
story) and if that trade-off is acceptable for us. I'm also thinking
that, for example, if you need to parse the packet data anyway for a drop
verdict, you might as well pass some meta data (that is set in the real
skb later on) for those packets that go up the stack.
next prev parent reply other threads:[~2016-04-04 13:37 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-02 1:21 [RFC PATCH 0/5] Add driver bpf hook for early packet drop Brenden Blanco
2016-04-02 1:21 ` [RFC PATCH 1/5] bpf: add PHYS_DEV prog type for early driver filter Brenden Blanco
2016-04-02 16:39 ` Tom Herbert
2016-04-03 7:02 ` Brenden Blanco
2016-04-04 22:07 ` Thomas Graf
2016-04-05 8:19 ` Jesper Dangaard Brouer
2016-04-04 8:49 ` Daniel Borkmann
2016-04-04 13:07 ` Jesper Dangaard Brouer
2016-04-04 13:36 ` Daniel Borkmann [this message]
2016-04-04 14:09 ` Tom Herbert
2016-04-04 15:12 ` Jesper Dangaard Brouer
2016-04-04 15:29 ` Brenden Blanco
2016-04-04 16:07 ` John Fastabend
2016-04-04 16:17 ` Brenden Blanco
2016-04-04 20:00 ` Alexei Starovoitov
2016-04-04 22:04 ` Thomas Graf
2016-04-05 2:25 ` Alexei Starovoitov
2016-04-05 8:11 ` Jesper Dangaard Brouer
2016-04-05 9:29 ` Jesper Dangaard Brouer
2016-04-05 22:06 ` Alexei Starovoitov
2016-04-04 14:33 ` Eric Dumazet
2016-04-04 15:18 ` Edward Cree
2016-04-02 1:21 ` [RFC PATCH 2/5] net: add ndo to set bpf prog in adapter rx Brenden Blanco
2016-04-02 1:21 ` [RFC PATCH 3/5] rtnl: add option for setting link bpf prog Brenden Blanco
2016-04-02 1:21 ` [RFC PATCH 4/5] mlx4: add support for fast rx drop bpf program Brenden Blanco
2016-04-02 2:08 ` Eric Dumazet
2016-04-02 2:47 ` Alexei Starovoitov
2016-04-04 14:57 ` Jesper Dangaard Brouer
2016-04-04 15:22 ` Eric Dumazet
2016-04-04 18:50 ` Alexei Starovoitov
2016-04-05 14:15 ` Or Gerlitz
2016-04-06 4:05 ` Brenden Blanco
2016-04-03 6:15 ` Brenden Blanco
2016-04-05 2:20 ` Brenden Blanco
2016-04-05 2:44 ` Eric Dumazet
2016-04-05 18:59 ` Eran Ben Elisha
2016-04-02 8:23 ` Jesper Dangaard Brouer
2016-04-03 6:11 ` Brenden Blanco
2016-04-04 18:27 ` Alexei Starovoitov
2016-04-05 6:04 ` Jesper Dangaard Brouer
2016-04-02 18:40 ` Johannes Berg
2016-04-03 6:38 ` Brenden Blanco
2016-04-04 7:35 ` Johannes Berg
2016-04-04 9:57 ` Daniel Borkmann
2016-04-04 18:46 ` Alexei Starovoitov
2016-04-04 21:01 ` Daniel Borkmann
2016-04-05 1:17 ` Alexei Starovoitov
2016-04-04 8:33 ` Jesper Dangaard Brouer
2016-04-04 9:22 ` Daniel Borkmann
2016-04-02 1:21 ` [RFC PATCH 5/5] Add sample for adding simple drop program to link Brenden Blanco
2016-04-06 19:48 ` Jesper Dangaard Brouer
2016-04-06 20:01 ` Jesper Dangaard Brouer
2016-04-06 23:11 ` Alexei Starovoitov
2016-04-06 20:03 ` Daniel Borkmann
2016-04-02 16:47 ` [RFC PATCH 0/5] Add driver bpf hook for early packet drop Tom Herbert
2016-04-03 5:41 ` Brenden Blanco
2016-04-04 7:48 ` Jesper Dangaard Brouer
2016-04-04 18:10 ` Alexei Starovoitov
2016-04-02 18:41 ` Johannes Berg
2016-04-02 22:57 ` Tom Herbert
2016-04-03 2:28 ` Lorenzo Colitti
2016-04-04 7:37 ` Johannes Berg
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