#include <linux/bpf.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_endian.h> int _version SEC("version") = 1; SEC("sk_skb1") int bpf_prog1(struct __sk_buff *skb) { void *data_end = (void *)(long) skb->data_end; void *data = (void *)(long) skb->data; __u32 lport = skb->local_port; __u32 rport = skb->remote_port; __u8 *d = data; __u32 len = (__u32) data_end - (__u32) data; int err; if (data + 10 > data_end) { err = bpf_skb_pull_data(skb, 10); if (err) return SK_DROP; data_end = (void *)(long)skb->data_end; data = (void *)(long)skb->data; if (data + 10 > data_end) return SK_DROP; } /* This write/read is a bit pointless but tests the verifier and * strparser handler for read/write pkt data and access into sk * fields. */ d = data; d[7] = 1; return skb->len; } char _license[] SEC("license") = "GPL";