xdp-tutorial | XDP tutorial - | Networking library

by xdp-project C Version: 2019-03-18-netdev0x13 License: No License

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kandi X-RAY | xdp-tutorial Summary

xdp-tutorial is a C library typically used in Networking applications. xdp-tutorial has no bugs, it has no vulnerabilities and it has medium support. You can download it from GitHub.

XDP tutorial

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Support

xdp-tutorial has a medium active ecosystem.

It has 1830 star(s) with 465 fork(s). There are 60 watchers for this library.

It had no major release in the last 12 months.

There are 125 open issues and 145 have been closed. On average issues are closed in 54 days. There are 10 open pull requests and 0 closed requests.

It has a neutral sentiment in the developer community.

The latest version of xdp-tutorial is 2019-03-18-netdev0x13

Quality

xdp-tutorial has 0 bugs and 0 code smells.

Security

xdp-tutorial has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

xdp-tutorial code analysis shows 0 unresolved vulnerabilities.

There are 0 security hotspots that need review.

License

xdp-tutorial does not have a standard license declared.

Check the repository for any license declaration and review the terms closely.

Without a license, all rights are reserved, and you cannot use the library in your applications.

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Community Discussions

Trending Discussions on xdp-tutorial

Accessing BPF maps from kernel space

What does proto means, xdp/ebpf?

bpf_xdp_adjust_meta() returns errcode -13 (permission denied)

how to forward packet between NIC and WIFI using XDP

AF_XDP: No packets for socket with queue-id 0 even though every packet is redirect

QUESTION

Accessing BPF maps from kernel space

Asked 2022-Jan-19 at 23:17

I am beginning with XDP and BPF maps.

I understand that to access a BPF map from userspace, we use bpf_* syscalls. For example, bpf_map_lookup_elem() is used to lookup an element of a BPF map in the userspace program. However, I noticed that the same syscalls are also used to access maps in the XDP programs loaded on the kernel (ref. here).

I assumed such programs should be running in the kernel space, and hence is there some other way these BPF maps should be accessed from the kernel space? Or is the XDP loaded program also part of the userspace but only running within the kernel?

...

ANSWER

Answered 2022-Jan-14 at 09:41

To lookup map elements from userspace, you should use the bpf(2) syscall, with command BPF_MAP_LOOKUP_ELEM. The main userspace library for BPF does expose this syscall command as bpf_map_lookup_elem().

To lookup map elements from BPF programs, you indeed need to use the bpf_map_lookup_elem BPF helper. In a nutshell, BPF helpers are kernel functions you can call from the BPF bytecode with instruction call.

Despite having the same name, they are however different things: the first is a library function, while the second is a BPF helper.

Source https://stackoverflow.com/questions/70707891

QUESTION

What does proto means, xdp/ebpf?

Asked 2021-Dec-21 at 13:37

What does proto signifies over here, I was following this https://github.com/xdp-project/xdp-tutorial/tree/master/tracing03-xdp-debug-print Can anyone explain what proto means in this context?

...

ANSWER

Answered 2021-Dec-21 at 13:37

In this context, given it seems to be displaying L2 information, proto is the Ethertype. It indicates the protocol of the next header (L3).

56710 is 0xDD86 (in big endian) in hexadecimal, which corresponds to the Ethertype of IPv6.

Source https://stackoverflow.com/questions/70124081

QUESTION

bpf_xdp_adjust_meta() returns errcode -13 (permission denied)

Asked 2021-Aug-09 at 08:16

Problem:

bpf_xdp_adjust_meta(ctx, -delta); is returning error code -13 (permission denied) when delta > 32.
But BPF and XDP Reference Guide states that there are 256 bytes headroom for metadata.
So did I misunderstand something or how can I use 256 bytes for metadata?

Program: ...

ANSWER

Answered 2021-Aug-09 at 08:16

The maximum room space for metadata is only 32 bytes, so what you observe is expected.

You can check this by reading the relevant kernel code, or the logs for the commit that introduced the feature.

The documentation that you cited refers to the room size for encapsulation headers that you can modify with bpf_xdp_adjust_head(), not to the size for metadata. Admittedly it's not clear from the text (but PRs are welcome!).

Source https://stackoverflow.com/questions/68705117

QUESTION

how to forward packet between NIC and WIFI using XDP

Asked 2020-Mar-26 at 19:33

I am trying to redirect the traffic between NIC and WIFI. I am trying to forwards packets from eth0, to send even packets through wlan0 and odd packets through wlan1.

I have not been able to successfully redirect packets from one interface to another unless those interfaces are virtual (such as the ones created in the xdp-tutorial).

Is there a simple example anywhere of redirecting ingress packets from eth0 with MAC 28:f1:f1:f1:f1:f1 to wlan0 with MAC e4:f1:f1:f1:f1:f1? (example MACs) So that if I connect a second computer through the ethernet port (assuming correct routing) and ping 8.8.8.8 it sends the packets through wlan0?

I would appreciate any help in this regard.

EDIT:

The code I am using is the one from xdp-tutorial

Step by step setup:

...

ANSWER

Answered 2020-Mar-26 at 03:25

As of date, Linux Kernel 5.5 houses bpf_prog_run_xdp function call for TUN and NIC drivers.

Source https://stackoverflow.com/questions/60828999

QUESTION

AF_XDP: No packets for socket with queue-id 0 even though every packet is redirect

Asked 2020-Mar-12 at 16:18

I am based on this tutorial: https://github.com/xdp-project/xdp-tutorial/tree/master/advanced03-AF_XDP

I create a socket with Queue-ID 0 in userspace. In my kernel af-xdp program I filter for UDP-packets and redirect them to the userspace socket via a xskmap.

Because I obviously want the userspace-program to receive packets, I redirect the packets in the kernel program to index 0:

...

ANSWER

Answered 2020-Mar-12 at 16:18

So this was discussed on IRC (#xdp, Freenode) and the xdp-newbies mailing list. Reporting here for the record.

The answer is that you did nothing wrong: With AF_XDP, a socket receives the packets from one hardware queue. You could have several sockets receiving packets from one queue, but you cannot have, as of this writing, one socket receiving on more than one queue. This is by design.

In your case, the Queue-ID: 0 that you associate to your socket indicates that it will receives packet from queue 0. This is why you don't see all packets received by the NIC before routing all flows to queue 0.

Reference for the ML discussion: link. Credits to Björn and Toke.

Source https://stackoverflow.com/questions/60603415

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