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1// SPDX-License-Identifier: GPL-2.0
2
3/* This parsing logic is taken from the open source library katran, a layer 4
4 * load balancer.
5 *
6 * This code logic using dynptrs can be found in test_parse_tcp_hdr_opt_dynptr.c
7 *
8 * https://github.com/facebookincubator/katran/blob/main/katran/lib/bpf/pckt_parsing.h
9 */
10
11#include <linux/bpf.h>
12#include <bpf/bpf_helpers.h>
13#include <linux/tcp.h>
14#include <stdbool.h>
15#include <linux/ipv6.h>
16#include <linux/if_ether.h>
17#include "test_tcp_hdr_options.h"
18
19char _license[] SEC("license") = "GPL";
20
21/* Kind number used for experiments */
22const __u32 tcp_hdr_opt_kind_tpr = 0xFD;
23/* Length of the tcp header option */
24const __u32 tcp_hdr_opt_len_tpr = 6;
25/* maximum number of header options to check to lookup server_id */
26const __u32 tcp_hdr_opt_max_opt_checks = 15;
27
28__u32 server_id;
29
30struct hdr_opt_state {
31 __u32 server_id;
32 __u8 byte_offset;
33 __u8 hdr_bytes_remaining;
34};
35
36static int parse_hdr_opt(const struct xdp_md *xdp, struct hdr_opt_state *state)
37{
38 const void *data = (void *)(long)xdp->data;
39 const void *data_end = (void *)(long)xdp->data_end;
40 __u8 *tcp_opt, kind, hdr_len;
41
42 tcp_opt = (__u8 *)(data + state->byte_offset);
43 if (tcp_opt + 1 > data_end)
44 return -1;
45
46 kind = tcp_opt[0];
47
48 if (kind == TCPOPT_EOL)
49 return -1;
50
51 if (kind == TCPOPT_NOP) {
52 state->hdr_bytes_remaining--;
53 state->byte_offset++;
54 return 0;
55 }
56
57 if (state->hdr_bytes_remaining < 2 ||
58 tcp_opt + sizeof(__u8) + sizeof(__u8) > data_end)
59 return -1;
60
61 hdr_len = tcp_opt[1];
62 if (hdr_len > state->hdr_bytes_remaining)
63 return -1;
64
65 if (kind == tcp_hdr_opt_kind_tpr) {
66 if (hdr_len != tcp_hdr_opt_len_tpr)
67 return -1;
68
69 if (tcp_opt + tcp_hdr_opt_len_tpr > data_end)
70 return -1;
71
72 state->server_id = *(__u32 *)&tcp_opt[2];
73 return 1;
74 }
75
76 state->hdr_bytes_remaining -= hdr_len;
77 state->byte_offset += hdr_len;
78 return 0;
79}
80
81SEC("xdp")
82int xdp_ingress_v6(struct xdp_md *xdp)
83{
84 const void *data = (void *)(long)xdp->data;
85 const void *data_end = (void *)(long)xdp->data_end;
86 struct hdr_opt_state opt_state = {};
87 __u8 tcp_hdr_opt_len = 0;
88 struct tcphdr *tcp_hdr;
89 __u64 tcp_offset = 0;
90 int err;
91
92 tcp_offset = sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
93 tcp_hdr = (struct tcphdr *)(data + tcp_offset);
94 if (tcp_hdr + 1 > data_end)
95 return XDP_DROP;
96
97 tcp_hdr_opt_len = (tcp_hdr->doff * 4) - sizeof(struct tcphdr);
98 if (tcp_hdr_opt_len < tcp_hdr_opt_len_tpr)
99 return XDP_DROP;
100
101 opt_state.hdr_bytes_remaining = tcp_hdr_opt_len;
102 opt_state.byte_offset = sizeof(struct tcphdr) + tcp_offset;
103
104 /* max number of bytes of options in tcp header is 40 bytes */
105 for (int i = 0; i < tcp_hdr_opt_max_opt_checks; i++) {
106 err = parse_hdr_opt(xdp, &opt_state);
107
108 if (err || !opt_state.hdr_bytes_remaining)
109 break;
110 }
111
112 if (!opt_state.server_id)
113 return XDP_DROP;
114
115 server_id = opt_state.server_id;
116
117 return XDP_PASS;
118}
1// SPDX-License-Identifier: GPL-2.0
2
3/* This parsing logic is taken from the open source library katran, a layer 4
4 * load balancer.
5 *
6 * This code logic using dynptrs can be found in test_parse_tcp_hdr_opt_dynptr.c
7 *
8 * https://github.com/facebookincubator/katran/blob/main/katran/lib/bpf/pckt_parsing.h
9 */
10
11#include <linux/bpf.h>
12#include <bpf/bpf_helpers.h>
13#include <linux/tcp.h>
14#include <stdbool.h>
15#include <linux/ipv6.h>
16#include <linux/if_ether.h>
17#include "test_tcp_hdr_options.h"
18
19char _license[] SEC("license") = "GPL";
20
21/* Kind number used for experiments */
22const __u32 tcp_hdr_opt_kind_tpr = 0xFD;
23/* Length of the tcp header option */
24const __u32 tcp_hdr_opt_len_tpr = 6;
25/* maximum number of header options to check to lookup server_id */
26const __u32 tcp_hdr_opt_max_opt_checks = 15;
27
28__u32 server_id;
29
30struct hdr_opt_state {
31 __u32 server_id;
32 __u8 byte_offset;
33 __u8 hdr_bytes_remaining;
34};
35
36static int parse_hdr_opt(const struct xdp_md *xdp, struct hdr_opt_state *state)
37{
38 const void *data = (void *)(long)xdp->data;
39 const void *data_end = (void *)(long)xdp->data_end;
40 __u8 *tcp_opt, kind, hdr_len;
41
42 tcp_opt = (__u8 *)(data + state->byte_offset);
43 if (tcp_opt + 1 > data_end)
44 return -1;
45
46 kind = tcp_opt[0];
47
48 if (kind == TCPOPT_EOL)
49 return -1;
50
51 if (kind == TCPOPT_NOP) {
52 state->hdr_bytes_remaining--;
53 state->byte_offset++;
54 return 0;
55 }
56
57 if (state->hdr_bytes_remaining < 2 ||
58 tcp_opt + sizeof(__u8) + sizeof(__u8) > data_end)
59 return -1;
60
61 hdr_len = tcp_opt[1];
62 if (hdr_len > state->hdr_bytes_remaining)
63 return -1;
64
65 if (kind == tcp_hdr_opt_kind_tpr) {
66 if (hdr_len != tcp_hdr_opt_len_tpr)
67 return -1;
68
69 if (tcp_opt + tcp_hdr_opt_len_tpr > data_end)
70 return -1;
71
72 state->server_id = *(__u32 *)&tcp_opt[2];
73 return 1;
74 }
75
76 state->hdr_bytes_remaining -= hdr_len;
77 state->byte_offset += hdr_len;
78 return 0;
79}
80
81SEC("xdp")
82int xdp_ingress_v6(struct xdp_md *xdp)
83{
84 const void *data = (void *)(long)xdp->data;
85 const void *data_end = (void *)(long)xdp->data_end;
86 struct hdr_opt_state opt_state = {};
87 __u8 tcp_hdr_opt_len = 0;
88 struct tcphdr *tcp_hdr;
89 __u64 tcp_offset = 0;
90 int err;
91
92 tcp_offset = sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
93 tcp_hdr = (struct tcphdr *)(data + tcp_offset);
94 if (tcp_hdr + 1 > data_end)
95 return XDP_DROP;
96
97 tcp_hdr_opt_len = (tcp_hdr->doff * 4) - sizeof(struct tcphdr);
98 if (tcp_hdr_opt_len < tcp_hdr_opt_len_tpr)
99 return XDP_DROP;
100
101 opt_state.hdr_bytes_remaining = tcp_hdr_opt_len;
102 opt_state.byte_offset = sizeof(struct tcphdr) + tcp_offset;
103
104 /* max number of bytes of options in tcp header is 40 bytes */
105 for (int i = 0; i < tcp_hdr_opt_max_opt_checks; i++) {
106 err = parse_hdr_opt(xdp, &opt_state);
107
108 if (err || !opt_state.hdr_bytes_remaining)
109 break;
110 }
111
112 if (!opt_state.server_id)
113 return XDP_DROP;
114
115 server_id = opt_state.server_id;
116
117 return XDP_PASS;
118}