1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022 Intel */
3
4 #include <linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6 #include <linux/if_ether.h>
7 #include <linux/ip.h>
8 #include <linux/errno.h>
9 #include "xsk_xdp_common.h"
10
11 struct {
12 __uint(type, BPF_MAP_TYPE_XSKMAP);
13 __uint(max_entries, 2);
14 __uint(key_size, sizeof(int));
15 __uint(value_size, sizeof(int));
16 } xsk SEC(".maps");
17
18 static unsigned int idx;
19 int adjust_value = 0;
20 int count = 0;
21
xsk_def_prog(struct xdp_md * xdp)22 SEC("xdp.frags") int xsk_def_prog(struct xdp_md *xdp)
23 {
24 return bpf_redirect_map(&xsk, 0, XDP_DROP);
25 }
26
xsk_xdp_drop(struct xdp_md * xdp)27 SEC("xdp.frags") int xsk_xdp_drop(struct xdp_md *xdp)
28 {
29 /* Drop every other packet */
30 if (idx++ % 2)
31 return XDP_DROP;
32
33 return bpf_redirect_map(&xsk, 0, XDP_DROP);
34 }
35
xsk_xdp_populate_metadata(struct xdp_md * xdp)36 SEC("xdp.frags") int xsk_xdp_populate_metadata(struct xdp_md *xdp)
37 {
38 void *data, *data_meta;
39 struct xdp_info *meta;
40 int err;
41
42 /* Reserve enough for all custom metadata. */
43 err = bpf_xdp_adjust_meta(xdp, -(int)sizeof(struct xdp_info));
44 if (err)
45 return XDP_DROP;
46
47 data = (void *)(long)xdp->data;
48 data_meta = (void *)(long)xdp->data_meta;
49
50 if (data_meta + sizeof(struct xdp_info) > data)
51 return XDP_DROP;
52
53 meta = data_meta;
54 meta->count = count++;
55
56 return bpf_redirect_map(&xsk, 0, XDP_DROP);
57 }
58
xsk_xdp_shared_umem(struct xdp_md * xdp)59 SEC("xdp") int xsk_xdp_shared_umem(struct xdp_md *xdp)
60 {
61 void *data = (void *)(long)xdp->data;
62 void *data_end = (void *)(long)xdp->data_end;
63 struct ethhdr *eth = data;
64
65 if (eth + 1 > data_end)
66 return XDP_DROP;
67
68 /* Redirecting packets based on the destination MAC address */
69 idx = ((unsigned int)(eth->h_dest[5])) / 2;
70 if (idx > MAX_SOCKETS)
71 return XDP_DROP;
72
73 return bpf_redirect_map(&xsk, idx, XDP_DROP);
74 }
75
xsk_xdp_adjust_tail(struct xdp_md * xdp)76 SEC("xdp.frags") int xsk_xdp_adjust_tail(struct xdp_md *xdp)
77 {
78 __u32 buff_len, curr_buff_len;
79 int ret;
80
81 buff_len = bpf_xdp_get_buff_len(xdp);
82 if (buff_len == 0)
83 return XDP_DROP;
84
85 ret = bpf_xdp_adjust_tail(xdp, adjust_value);
86 if (ret < 0) {
87 /* Handle unsupported cases */
88 if (ret == -EOPNOTSUPP) {
89 /* Set adjust_value to -EOPNOTSUPP to indicate to userspace that this case
90 * is unsupported
91 */
92 adjust_value = -EOPNOTSUPP;
93 return bpf_redirect_map(&xsk, 0, XDP_DROP);
94 }
95
96 return XDP_DROP;
97 }
98
99 curr_buff_len = bpf_xdp_get_buff_len(xdp);
100 if (curr_buff_len != buff_len + adjust_value)
101 return XDP_DROP;
102
103 if (curr_buff_len > buff_len) {
104 __u32 *pkt_data = (void *)(long)xdp->data;
105 __u32 len, words_to_end, seq_num;
106
107 len = curr_buff_len - PKT_HDR_ALIGN;
108 words_to_end = len / sizeof(*pkt_data) - 1;
109 seq_num = words_to_end;
110
111 /* Convert sequence number to network byte order. Store this in the last 4 bytes of
112 * the packet. Use 'adjust_value' to determine the position at the end of the
113 * packet for storing the sequence number.
114 */
115 seq_num = __constant_htonl(words_to_end);
116 bpf_xdp_store_bytes(xdp, curr_buff_len - sizeof(seq_num), &seq_num,
117 sizeof(seq_num));
118 }
119
120 return bpf_redirect_map(&xsk, 0, XDP_DROP);
121 }
122
123 char _license[] SEC("license") = "GPL";
124