Questions tagged [xdp-ebpf]
12 questions
3
votes
1 answer
Thread safe operations on XDP
I was able to confirm from the documentation that bpf_map_update_elem is an atomic operation if done on HASH_MAPs. Source (https://man7.org/linux/man-pages/man2/bpf.2.html). [Cite: map_update_elem() replaces existing elements atomically]
My question…
Rishab
- 73
- 4
1
vote
2 answers
kernel compilation error when CONFIG_DEBUG_INFO_BTF is enabled
FAILED: load BTF from vmlinux: No such file or directory
make: *** [Makefile:1164: vmlinux] Error 255
make: *** Deleting file 'vmlinux'
root@akb:/home/akb/SRC/net/net-next#
I have to enable BTF for my BPF xdp program to work.
Environment :on…
Aravind Buduri
- 11
- 1
- 3
1
vote
1 answer
Unable to fetch data using bpf_map_lookup_elem()
I am trying to write a code for XDP where a user space program will populate a bpf map and then later the Kernel will look into the map. For creating the map I have added a SEC(".maps") in the bpf_obj file that will get loaded into the kernel.…
Rishab
- 73
- 4
1
vote
1 answer
Multiple ebpf hooks cgroup_skb
I have basic question on ebpf behavior when multiple ebpf hooks are loaded(not using chaining) simultaneously in kernel. Are all of those hooks invoked? For example, I loaded my ebpf program which has cgroup_skb/ingress hook. The ebpf hooks…
Jeelani Syed
- 11
- 1
0
votes
1 answer
pass by value not supported XDP
I am creating a function to loop through some loops and try to match a set. It is supposed to work fine, but unfortunately, it is not. I get a "pass by value not supported" error. How can I fix this?
int matchSet(Program p, int match[], int…
Fabian
- 24
- 4
0
votes
1 answer
How do I copy data to buffer in eBPF?
I'm wanting to store the packets' payload to my custom buffer in eBPF & XDP hook. But I can't pass the verifier. I learned others' code found no difference.
In the code, I checked the length of payload should be less than MTU, which is 1500 in my…
Zezhou Wang
- 21
- 3
0
votes
1 answer
How to generate delay using eBPF kernel program
I'm trying to generate delay in acknowledgement using eBPF kernel program for egress packet.
I'm running the python+c program using bcc.
i tried mdelay/msleep/udelay etc functions with delay.h library in c, it gives me LLVM error that "Program using…
Ayushri Arora
- 49
- 1
0
votes
1 answer
ebpf verifier fails for bpf_csum_diff()
Not able to understand why the following code fails verifier. I am doing all possible validations in this test function.
{
if (tcph + 1 > data_end)
return XDP_DROP;
tcp_len = tcph->doff * 4;
if (tcp_len < sizeof(*tcph))
…
user2126078
- 1
- 2
0
votes
1 answer
Sending custom data to socket using eBPF
I'm trying, finally, to understand eBPF and maybe use it in an upcoming project.
For sake of simplicity I started with reading bcc documentation.
In my project I'll need to send some data over network upon some kernel function calls.
Can that be…
David
- 182
- 1
- 1
- 8
0
votes
0 answers
How to parse through bytes in a packets without using helper headers with XDP in C?
I am new to using XDP and trying to teach myself how to create ELF programs to do a variety of XDP actions. I am also a beginner to using C.
How can I parse through packets to show data from specific bytes in the data without using helper headers…
Dave
- 727
- 1
- 9
- 20
0
votes
0 answers
Update destination port with bcc and xdp
I am running an application in port 80 in a container. Now I want to call it by using port 90 and xdp will change the port from 90 to 80. But for some reason, I am getting any response or server is not getting any call either. Here is my ebf…
Omar Faroque Anik
- 2,531
- 1
- 29
- 42
0
votes
0 answers
xdp_md->egress_ifindex not found | XDP Ebpf
So I have this code in my ebpf program and so on my system struct xdp_md does exists.
struct xdp_md {
__u32 data;
__u32 data_end;
__u32 data_meta;
/* Below access go through struct xdp_rxq_info */
__u32 ingress_ifindex; /*…
user786
- 3,902
- 4
- 40
- 72