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From: Martin KaFai Lau <kafai@fb.com>
To: Joe Stringer <joe@wand.net.nz>
Cc: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
	<daniel@iogearbox.net>, <ast@kernel.org>,
	<eric.dumazet@gmail.com>, <lmb@cloudflare.com>
Subject: Re: [PATCHv3 bpf-next 1/5] bpf: Add socket assign support
Date: Fri, 27 Mar 2020 11:44:43 -0700
Message-ID: <20200327184443.msxv27ft5vbqmyze@kafai-mbp> (raw)
In-Reply-To: <20200327042556.11560-2-joe@wand.net.nz>

On Thu, Mar 26, 2020 at 09:25:52PM -0700, Joe Stringer wrote:
> Add support for TPROXY via a new bpf helper, bpf_sk_assign().
> 
> This helper requires the BPF program to discover the socket via a call
> to bpf_sk*_lookup_*(), then pass this socket to the new helper. The
> helper takes its own reference to the socket in addition to any existing
> reference that may or may not currently be obtained for the duration of
> BPF processing. For the destination socket to receive the traffic, the
> traffic must be routed towards that socket via local route. The
> simplest example route is below, but in practice you may want to route
> traffic more narrowly (eg by CIDR):
> 
>   $ ip route add local default dev lo
> 
> This patch avoids trying to introduce an extra bit into the skb->sk, as
> that would require more invasive changes to all code interacting with
> the socket to ensure that the bit is handled correctly, such as all
> error-handling cases along the path from the helper in BPF through to
> the orphan path in the input. Instead, we opt to use the destructor
> variable to switch on the prefetch of the socket.
> 
> Signed-off-by: Joe Stringer <joe@wand.net.nz>
> ---
> v3: Check skb_sk_is_prefetched() in TC level redirect check
> v2: Use skb->destructor to determine socket prefetch usage instead of
>       introducing a new metadata_dst
>     Restrict socket assign to same netns as TC device
>     Restrict assigning reuseport sockets
>     Adjust commit wording
> v1: Initial version
> ---
>  include/net/sock.h             |  7 +++++++
>  include/uapi/linux/bpf.h       | 25 ++++++++++++++++++++++++-
>  net/core/filter.c              | 31 +++++++++++++++++++++++++++++++
>  net/core/sock.c                |  9 +++++++++
>  net/ipv4/ip_input.c            |  3 ++-
>  net/ipv6/ip6_input.c           |  3 ++-
>  net/sched/act_bpf.c            |  3 +++
>  tools/include/uapi/linux/bpf.h | 25 ++++++++++++++++++++++++-
>  8 files changed, 102 insertions(+), 4 deletions(-)
> 

[ ... ]

> diff --git a/net/core/sock.c b/net/core/sock.c
> index 0fc8937a7ff4..cfaf60267360 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2071,6 +2071,15 @@ void sock_efree(struct sk_buff *skb)
>  }
>  EXPORT_SYMBOL(sock_efree);
>  
> +/* Buffer destructor for prefetch/receive path where reference count may
> + * not be held, e.g. for listen sockets.
> + */
> +void sock_pfree(struct sk_buff *skb)
> +{
> +	sock_edemux(skb);
Nit. may be directly call sock_gen_put().

> +}
> +EXPORT_SYMBOL(sock_pfree);
> +

  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27  4:25 [PATCHv3 bpf-next 0/5] Add bpf_sk_assign eBPF helper Joe Stringer
2020-03-27  4:25 ` [PATCHv3 bpf-next 1/5] bpf: Add socket assign support Joe Stringer
2020-03-27 18:44   ` Martin KaFai Lau [this message]
2020-03-27  4:25 ` [PATCHv3 bpf-next 2/5] net: Track socket refcounts in skb_steal_sock() Joe Stringer
2020-03-27 18:45   ` Martin KaFai Lau
2020-03-27  4:25 ` [PATCHv3 bpf-next 3/5] bpf: Don't refcount LISTEN sockets in sk_assign() Joe Stringer
2020-03-27 14:26   ` Jamal Hadi Salim
2020-03-27 17:38     ` Joe Stringer
2020-03-27 18:29       ` Jamal Hadi Salim
2020-03-27  4:25 ` [PATCHv3 bpf-next 4/5] selftests: bpf: add test for sk_assign Joe Stringer
2020-03-27  4:25 ` [PATCHv3 bpf-next 5/5] selftests: bpf: Extend sk_assign tests for UDP Joe Stringer
     [not found]   ` <CACAyw9-GOw5tkR8n6p7Kct9-wq4B-9ka-X8R2V8uZv8VWUY5UQ@mail.gmail.com>
2020-03-27 19:37     ` Joe Stringer
2020-03-27  5:02 ` [PATCHv3 bpf-next 0/5] Add bpf_sk_assign eBPF helper Alexei Starovoitov
2020-03-27  5:42   ` Eric Dumazet
2020-03-27 14:13 ` Jamal Hadi Salim
2020-03-27 17:43   ` Joe Stringer
2020-03-27 18:34     ` Jamal Hadi Salim
2020-03-27 18:46 ` Martin KaFai Lau
2020-03-27 21:05   ` Joe Stringer
2020-03-28 17:25     ` Daniel Borkmann
2020-03-28 17:42       ` Joe Stringer

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