| /* 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 <linux/skbuff.h> |
| #include <linux/netdevice.h> |
| #include <uapi/linux/bpf.h> |
| #include <linux/version.h> |
| #include "bpf_helpers.h" |
| |
| #define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;}) |
| |
| /* 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/__netif_receive_skb_core") |
| int bpf_prog1(struct pt_regs *ctx) |
| { |
| /* attaches to kprobe netif_receive_skb, |
| * looks for packets on loobpack device and prints them |
| */ |
| char devname[IFNAMSIZ]; |
| struct net_device *dev; |
| struct sk_buff *skb; |
| int len; |
| |
| /* non-portable! works for the given kernel only */ |
| skb = (struct sk_buff *) PT_REGS_PARM1(ctx); |
| dev = _(skb->dev); |
| len = _(skb->len); |
| |
| bpf_probe_read(devname, sizeof(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; |
