| /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of version 2 of the GNU General Public |
| * License as published by the Free Software Foundation. |
| */ |
| #include "vmlinux.h" |
| #include "net_shared.h" |
| #include <linux/version.h> |
| #include <bpf/bpf_helpers.h> |
| #include <bpf/bpf_core_read.h> |
| #include <bpf/bpf_tracing.h> |
| |
| /* kprobe is NOT a stable ABI |
| * kernel functions can be removed, renamed or completely change semantics. |
| * Number of arguments and their positions can change, etc. |
| * In such case this bpf+kprobe example will no longer be meaningful |
| */ |
| SEC("kprobe.multi/__netif_receive_skb_core*") |
| int bpf_prog1(struct pt_regs *ctx) |
| { |
| /* attaches to kprobe __netif_receive_skb_core, |
| * looks for packets on loobpack device and prints them |
| * (wildcard is used for avoiding symbol mismatch due to optimization) |
| */ |
| char devname[IFNAMSIZ]; |
| struct net_device *dev; |
| struct sk_buff *skb; |
| int len; |
| |
| bpf_core_read(&skb, sizeof(skb), (void *)PT_REGS_PARM1(ctx)); |
| dev = BPF_CORE_READ(skb, dev); |
| len = BPF_CORE_READ(skb, len); |
| |
| BPF_CORE_READ_STR_INTO(&devname, dev, name); |
| |
| if (devname[0] == 'l' && devname[1] == 'o') { |
| char fmt[] = "skb %p len %d\n"; |
| /* using bpf_trace_printk() for DEBUG ONLY */ |
| bpf_trace_printk(fmt, sizeof(fmt), skb, len); |
| } |
| |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |
| u32 _version SEC("version") = LINUX_VERSION_CODE; |
