1 #include <linux/bpf.h> 2 #include <linux/if_ether.h> 3 #include <linux/pkt_cls.h> 4 5 #include <bpf/bpf_helpers.h> 6 7 #define META_SIZE 32 8 9 #define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem 10 11 /* Demonstrates how metadata can be passed from an XDP program to a TC program 12 * using bpf_xdp_adjust_meta. 13 * For the sake of testing the metadata support in drivers, the XDP program uses 14 * a fixed-size payload after the Ethernet header as metadata. The TC program 15 * copies the metadata it receives into a map so it can be checked from 16 * userspace. 17 */ 18 19 struct { 20 __uint(type, BPF_MAP_TYPE_ARRAY); 21 __uint(max_entries, 1); 22 __type(key, __u32); 23 __uint(value_size, META_SIZE); 24 } test_result SEC(".maps"); 25 26 SEC("tc") 27 int ing_cls(struct __sk_buff *ctx) 28 { 29 __u8 *data, *data_meta; 30 __u32 key = 0; 31 32 data_meta = ctx_ptr(ctx, data_meta); 33 data = ctx_ptr(ctx, data); 34 35 if (data_meta + META_SIZE > data) 36 return TC_ACT_SHOT; 37 38 bpf_map_update_elem(&test_result, &key, data_meta, BPF_ANY); 39 40 return TC_ACT_SHOT; 41 } 42 43 SEC("xdp") 44 int ing_xdp(struct xdp_md *ctx) 45 { 46 __u8 *data, *data_meta, *data_end, *payload; 47 struct ethhdr *eth; 48 int ret; 49 50 ret = bpf_xdp_adjust_meta(ctx, -META_SIZE); 51 if (ret < 0) 52 return XDP_DROP; 53 54 data_meta = ctx_ptr(ctx, data_meta); 55 data_end = ctx_ptr(ctx, data_end); 56 data = ctx_ptr(ctx, data); 57 58 eth = (struct ethhdr *)data; 59 payload = data + sizeof(struct ethhdr); 60 61 if (payload + META_SIZE > data_end || 62 data_meta + META_SIZE > data) 63 return XDP_DROP; 64 65 /* The Linux networking stack may send other packets on the test 66 * interface that interfere with the test. Just drop them. 67 * The test packets can be recognized by their ethertype of zero. 68 */ 69 if (eth->h_proto != 0) 70 return XDP_DROP; 71 72 __builtin_memcpy(data_meta, payload, META_SIZE); 73 return XDP_PASS; 74 } 75 76 char _license[] SEC("license") = "GPL"; 77