如何在Linux内核中找到sk_buff的所有者套接字? [英] How to find owner socket of sk_buff in Linux kernel?

问题描述

我正在尝试找到 sk_buff 实例的所有者套接字，例如 skb .我的最终目标是找到一个特定的TCP选项，并以某种方式让用户空间应用程序知道.我计划在找到TCP选项时设置一个套接字选项，并让用户空间应用程序调用 getsockopt().因此，我需要知道 sk_buff 和 sock 之间的所有权.

I'm trying to find the owner socket of an sk_buff instance, say, skb. My ultimate goal is to find a specific TCP option and somehow let the user space application to know. I plan to set a socket option when I find the TCP option and let the user space app to call getsockopt(). Therefore I need to know the ownership between sk_buff and sock.

我发现sk_buff中有一个字段:

I find there is a field in sk_buff:

struct sock *sk;

但是，当我尝试在 tcp_parse_options ，我总是得到 skb-> sk == NULL .

However, when I try to retrieve this field at tcp_parse_options in tcp_input.c, I always get skb->sk == NULL.

所以我想知道如何在这里找到所有者?

So I'm wondering how can I find the owner here?

此外，我发现3个地方似乎在设置所有者套接字:

Also, I find 3 places that seems to set the owner socket:

http://lxr.free-electronics.com/source/net/ipv4/tcp_input.c?v=3.11#L4181

http://lxr.free-electronics.com/source/net/ipv4/tcp_input.c?v=3.11#L4196

http://lxr.free-electronics.com/source/net/ipv4/tcp_input.c?v=3.11#L4456

我还在 sk_buff 中添加了一个新标记，用于指示并将其设置为 tcp_parse_options .然后我在这三个地方检查这个标志.但是它们都不显示标志已设置，因此我无法确定是否设置套接字选项.

I also add a new flag in sk_buff for indicating and set it at tcp_parse_options. Then I check this flag at these three places. But none of them shows the flag is set so that I cannot determine whether to set the socket option.

对这个问题有任何想法或建议吗?

Any idea or suggestion for this problem?

提前谢谢！

推荐答案

从sk_buff(skb)中，您可以通过以下方式获得袜子(sk):

From the sk_buff (skb) you can get the sock (sk) with something like this:

const struct tcphdr *th = tcp_hdr(skb);
struct sock *sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
if (sk)
    struct socket* = sk->sk_socket;

对我有用.不要忘记添加正确的标题.

That worked for me. Don't forget to add the right headers.

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