1 #include <linux/bpf.h> 2 #include <bpf/bpf_helpers.h> 3 #include <bpf/bpf_endian.h> 4 5 int _version SEC("version") = 1; 6 7 SEC("sk_skb1") 8 int bpf_prog1(struct __sk_buff *skb) 9 { 10 void *data_end = (void *)(long) skb->data_end; 11 void *data = (void *)(long) skb->data; 12 __u32 lport = skb->local_port; 13 __u32 rport = skb->remote_port; 14 __u8 *d = data; 15 int err; 16 17 if (data + 10 > data_end) { 18 err = bpf_skb_pull_data(skb, 10); 19 if (err) 20 return SK_DROP; 21 22 data_end = (void *)(long)skb->data_end; 23 data = (void *)(long)skb->data; 24 if (data + 10 > data_end) 25 return SK_DROP; 26 } 27 28 /* This write/read is a bit pointless but tests the verifier and 29 * strparser handler for read/write pkt data and access into sk 30 * fields. 31 */ 32 d = data; 33 d[7] = 1; 34 return skb->len; 35 } 36 37 char _license[] SEC("license") = "GPL"; 38