bpf/progs/sockmap_parse_prog.c

0001 #include <linux/bpf.h>
0002 #include <bpf/bpf_helpers.h>
0003 #include <bpf/bpf_endian.h>
0004
0005 SEC("sk_skb1")
0006 int bpf_prog1(struct __sk_buff *skb)
0007 {
0008     void *data_end = (void *)(long) skb->data_end;
0009     void *data = (void *)(long) skb->data;
0010     __u8 *d = data;
0011     int err;
0012
0013     if (data + 10 > data_end) {
0014         err = bpf_skb_pull_data(skb, 10);
0015         if (err)
0016             return SK_DROP;
0017
0018         data_end = (void *)(long)skb->data_end;
0019         data = (void *)(long)skb->data;
0020         if (data + 10 > data_end)
0021             return SK_DROP;
0022     }
0023
0024     /* This write/read is a bit pointless but tests the verifier and
0025      * strparser handler for read/write pkt data and access into sk
0026      * fields.
0027      */
0028     d = data;
0029     d[7] = 1;
0030     return skb->len;
0031 }
0032
0033 char _license[] SEC("license") = "GPL";