| /* 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; |