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From: Jakub Sitnicki <jakub@cloudflare.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	duanxiongchun@bytedance.com,
	Dongdong Wang <wangdongdong.6@bytedance.com>,
	Jiang Wang <jiang.wang@bytedance.com>,
	Cong Wang <cong.wang@bytedance.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Lorenz Bauer <lmb@cloudflare.com>,
	John Fastabend <john.fastabend@gmail.com>
Subject: Re: [Patch bpf-next v6 4/8] skmsg: move sk_redir from TCP_SKB_CB to skb
Date: Tue, 23 Feb 2021 19:36:57 +0100
Message-ID: <874ki24omu.fsf@cloudflare.com> (raw)
In-Reply-To: <CAM_iQpWofNM=erfyP8b_qrezJN6d51UDW5bfgo2LHkPOTXqm8Q@mail.gmail.com>

On Tue, Feb 23, 2021 at 07:04 PM CET, Cong Wang wrote:
> On Tue, Feb 23, 2021 at 9:53 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>> Based on what I've seen around, mask for sanitizing tagged pointers is
>> usually derived from the flag(s). For instance:
>>
>> #define SKB_DST_NOREF   1UL
>> #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
>>
>> #define SK_USER_DATA_NOCOPY     1UL
>> #define SK_USER_DATA_BPF        2UL     /* Managed by BPF */
>> #define SK_USER_DATA_PTRMASK    ~(SK_USER_DATA_NOCOPY | SK_USER_DATA_BPF)
>>
>> Using ~(BPF_F_INGRESS) expression would be like substituting mask
>> definition.
>
> Yes, that is why I said we need a mask.

OK

>
>>
>> Alternatively we could clear _skb_refdest after clone, but before
>> enqueuing the skb in ingress_skb. And only for when we're redirecting.
>>
>> I believe that would be in sk_psock_skb_redirect, right before skb_queue_tail.
>
> Hmm? We definitely cannot clear skb->_sk_redir there, as it is used after
> enqueued in ingress_skb, that is in sk_psock_backlog().

You're right. I focused on the sk pointer and forgot it also carries the
ingress flag.

  reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-20  5:29 [Patch bpf-next v6 0/8] sock_map: clean up and refactor code for BPF_SK_SKB_VERDICT Cong Wang
2021-02-20  5:29 ` [Patch bpf-next v6 1/8] bpf: clean up sockmap related Kconfigs Cong Wang
2021-02-22  8:51   ` Jakub Sitnicki
2021-02-22 23:23     ` Cong Wang
2021-02-20  5:29 ` [Patch bpf-next v6 2/8] skmsg: get rid of struct sk_psock_parser Cong Wang
2021-02-20  5:29 ` [Patch bpf-next v6 3/8] bpf: compute data_end dynamically with JIT code Cong Wang
2021-02-20  5:29 ` [Patch bpf-next v6 4/8] skmsg: move sk_redir from TCP_SKB_CB to skb Cong Wang
2021-02-22 12:20   ` Jakub Sitnicki
2021-02-22 19:27     ` Cong Wang
2021-02-23 17:52       ` Jakub Sitnicki
2021-02-23 18:04         ` Cong Wang
2021-02-23 18:36           ` Jakub Sitnicki [this message]
2021-02-20  5:29 ` [Patch bpf-next v6 5/8] sock_map: rename skb_parser and skb_verdict Cong Wang
2021-02-22 12:28   ` Jakub Sitnicki
2021-02-22 19:32     ` Cong Wang
2021-02-20  5:29 ` [Patch bpf-next v6 6/8] sock_map: make sock_map_prog_update() static Cong Wang
2021-02-22 12:29   ` Jakub Sitnicki
2021-02-20  5:29 ` [Patch bpf-next v6 7/8] skmsg: make __sk_psock_purge_ingress_msg() static Cong Wang
2021-02-22 12:30   ` Jakub Sitnicki
2021-02-20  5:29 ` [Patch bpf-next v6 8/8] skmsg: get rid of sk_psock_bpf_run() Cong Wang
2021-02-22 12:31   ` Jakub Sitnicki
2021-02-22 12:32 ` [Patch bpf-next v6 0/8] sock_map: clean up and refactor code for BPF_SK_SKB_VERDICT Jakub Sitnicki

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