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 static unsigned int drop_idx;
30
31 /* Drop every other packet */
32 if (drop_idx++ % 2)
33 return XDP_DROP;
34
35 return bpf_redirect_map(&xsk, 0, XDP_DROP);
36 }
37
xsk_xdp_populate_metadata(struct xdp_md * xdp)38 SEC("xdp.frags") int xsk_xdp_populate_metadata(struct xdp_md *xdp)
39 {
40 void *data, *data_meta;
41 struct xdp_info *meta;
42 int err;
43
44 /* Reserve enough for all custom metadata. */
45 err = bpf_xdp_adjust_meta(xdp, -(int)sizeof(struct xdp_info));
46 if (err)
47 return XDP_DROP;
48
49 data = (void *)(long)xdp->data;
50 data_meta = (void *)(long)xdp->data_meta;
51
52 if (data_meta + sizeof(struct xdp_info) > data)
53 return XDP_DROP;
54
55 meta = data_meta;
56 meta->count = count++;
57
58 return bpf_redirect_map(&xsk, 0, XDP_DROP);
59 }
60
xsk_xdp_shared_umem(struct xdp_md * xdp)61 SEC("xdp") int xsk_xdp_shared_umem(struct xdp_md *xdp)
62 {
63 void *data = (void *)(long)xdp->data;
64 void *data_end = (void *)(long)xdp->data_end;
65 struct ethhdr *eth = data;
66
67 if (eth + 1 > data_end)
68 return XDP_DROP;
69
70 /* Redirecting packets based on the destination MAC address */
71 idx = ((unsigned int)(eth->h_dest[5])) / 2;
72 if (idx > MAX_SOCKETS)
73 return XDP_DROP;
74
75 return bpf_redirect_map(&xsk, idx, XDP_DROP);
76 }
77
xsk_xdp_adjust_tail(struct xdp_md * xdp)78 SEC("xdp.frags") int xsk_xdp_adjust_tail(struct xdp_md *xdp)
79 {
80 __u32 buff_len, curr_buff_len;
81 int ret;
82
83 buff_len = bpf_xdp_get_buff_len(xdp);
84 if (buff_len == 0)
85 return XDP_DROP;
86
87 ret = bpf_xdp_adjust_tail(xdp, adjust_value);
88 if (ret < 0) {
89 /* Handle unsupported cases */
90 if (ret == -EOPNOTSUPP) {
91 /* Set adjust_value to -EOPNOTSUPP to indicate to userspace that this case
92 * is unsupported
93 */
94 adjust_value = -EOPNOTSUPP;
95 return bpf_redirect_map(&xsk, 0, XDP_DROP);
96 }
97
98 return XDP_DROP;
99 }
100
101 curr_buff_len = bpf_xdp_get_buff_len(xdp);
102 if (curr_buff_len != buff_len + adjust_value)
103 return XDP_DROP;
104
105 if (curr_buff_len > buff_len) {
106 __u32 *pkt_data = (void *)(long)xdp->data;
107 __u32 len, words_to_end, seq_num;
108
109 len = curr_buff_len - PKT_HDR_ALIGN;
110 words_to_end = len / sizeof(*pkt_data) - 1;
111 seq_num = words_to_end;
112
113 /* Convert sequence number to network byte order. Store this in the last 4 bytes of
114 * the packet. Use 'adjust_value' to determine the position at the end of the
115 * packet for storing the sequence number.
116 */
117 seq_num = __constant_htonl(words_to_end);
118 bpf_xdp_store_bytes(xdp, curr_buff_len - sizeof(seq_num), &seq_num,
119 sizeof(seq_num));
120 }
121
122 return bpf_redirect_map(&xsk, 0, XDP_DROP);
123 }
124
125 char _license[] SEC("license") = "GPL";
126