1 #include <linux/bpf.h> 2 #include "bpf_helpers.h" 3 #include "bpf_endian.h" 4 5 int _version SEC("version") = 1; 6 7 SEC("sk_skb1") bpf_prog1(struct __sk_buff * skb)8int 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 __u32 len = (__u32) data_end - (__u32) data; 16 int err; 17 18 if (data + 10 > data_end) { 19 err = bpf_skb_pull_data(skb, 10); 20 if (err) 21 return SK_DROP; 22 23 data_end = (void *)(long)skb->data_end; 24 data = (void *)(long)skb->data; 25 if (data + 10 > data_end) 26 return SK_DROP; 27 } 28 29 /* This write/read is a bit pointless but tests the verifier and 30 * strparser handler for read/write pkt data and access into sk 31 * fields. 32 */ 33 d = data; 34 d[7] = 1; 35 return skb->len; 36 } 37 38 char _license[] SEC("license") = "GPL"; 39