1 /* SPDX-License-Identifier: GPL-2.0 */
2 // Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
3
4 #include <stddef.h>
5 #include <stdbool.h>
6 #include <string.h>
7 #include <linux/bpf.h>
8 #include <linux/if_ether.h>
9 #include <linux/in.h>
10 #include <linux/ip.h>
11 #include <linux/ipv6.h>
12 #include <linux/pkt_cls.h>
13 #include <linux/tcp.h>
14 #include <sys/socket.h>
15 #include <bpf/bpf_helpers.h>
16 #include <bpf/bpf_endian.h>
17
18 char _license[] SEC("license") = "GPL";
19
20 /* Fill 'tuple' with L3 info, and attempt to find L4. On fail, return NULL. */
21 static struct bpf_sock_tuple *get_tuple(void *data, __u64 nh_off,
22 void *data_end, __u16 eth_proto,
23 bool *ipv4)
24 {
25 struct bpf_sock_tuple *result;
26 __u64 ihl_len = 0;
27 __u8 proto = 0;
28
29 if (eth_proto == bpf_htons(ETH_P_IP)) {
30 struct iphdr *iph = (struct iphdr *)(data + nh_off);
31
32 if (iph + 1 > data_end)
33 return NULL;
34 ihl_len = iph->ihl * 4;
35 proto = iph->protocol;
36 *ipv4 = true;
37 result = (struct bpf_sock_tuple *)&iph->saddr;
38 } else if (eth_proto == bpf_htons(ETH_P_IPV6)) {
39 struct ipv6hdr *ip6h = (struct ipv6hdr *)(data + nh_off);
40
41 if (ip6h + 1 > data_end)
42 return NULL;
43 ihl_len = sizeof(*ip6h);
44 proto = ip6h->nexthdr;
45 *ipv4 = true;
46 result = (struct bpf_sock_tuple *)&ip6h->saddr;
47 }
48
49 if (data + nh_off + ihl_len > data_end || proto != IPPROTO_TCP)
50 return NULL;
51
52 return result;
53 }
54
55 SEC("?tc")
56 int sk_lookup_success(struct __sk_buff *skb)
57 {
58 void *data_end = (void *)(long)skb->data_end;
59 void *data = (void *)(long)skb->data;
60 struct ethhdr *eth = (struct ethhdr *)(data);
61 struct bpf_sock_tuple *tuple;
62 struct bpf_sock *sk;
63 size_t tuple_len;
64 bool ipv4;
65
66 if (eth + 1 > data_end)
67 return TC_ACT_SHOT;
68
69 tuple = get_tuple(data, sizeof(*eth), data_end, eth->h_proto, &ipv4);
70 if (!tuple || tuple + sizeof *tuple > data_end)
71 return TC_ACT_SHOT;
72
73 tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6);
74 sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0);
75 bpf_printk("sk=%d\n", sk ? 1 : 0);
76 if (sk)
77 bpf_sk_release(sk);
78 return sk ? TC_ACT_OK : TC_ACT_UNSPEC;
79 }
80
81 SEC("?tc")
82 int sk_lookup_success_simple(struct __sk_buff *skb)
83 {
84 struct bpf_sock_tuple tuple = {};
85 struct bpf_sock *sk;
86
87 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
88 if (sk)
89 bpf_sk_release(sk);
90 return 0;
91 }
92
93 SEC("?tc")
94 int err_use_after_free(struct __sk_buff *skb)
95 {
96 struct bpf_sock_tuple tuple = {};
97 struct bpf_sock *sk;
98 __u32 family = 0;
99
100 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
101 if (sk) {
102 bpf_sk_release(sk);
103 family = sk->family;
104 }
105 return family;
106 }
107
108 SEC("?tc")
109 int err_modify_sk_pointer(struct __sk_buff *skb)
110 {
111 struct bpf_sock_tuple tuple = {};
112 struct bpf_sock *sk;
113
114 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
115 if (sk) {
116 sk += 1;
117 bpf_sk_release(sk);
118 }
119 return 0;
120 }
121
122 SEC("?tc")
123 int err_modify_sk_or_null_pointer(struct __sk_buff *skb)
124 {
125 struct bpf_sock_tuple tuple = {};
126 struct bpf_sock *sk;
127
128 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
129 sk += 1;
130 if (sk)
131 bpf_sk_release(sk);
132 return 0;
133 }
134
135 SEC("?tc")
136 int err_no_release(struct __sk_buff *skb)
137 {
138 struct bpf_sock_tuple tuple = {};
139
140 bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
141 return 0;
142 }
143
144 SEC("?tc")
145 int err_release_twice(struct __sk_buff *skb)
146 {
147 struct bpf_sock_tuple tuple = {};
148 struct bpf_sock *sk;
149
150 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
151 bpf_sk_release(sk);
152 bpf_sk_release(sk);
153 return 0;
154 }
155
156 SEC("?tc")
157 int err_release_unchecked(struct __sk_buff *skb)
158 {
159 struct bpf_sock_tuple tuple = {};
160 struct bpf_sock *sk;
161
162 sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
163 bpf_sk_release(sk);
164 return 0;
165 }
166
167 void lookup_no_release(struct __sk_buff *skb)
168 {
169 struct bpf_sock_tuple tuple = {};
170 bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), BPF_F_CURRENT_NETNS, 0);
171 }
172
173 SEC("?tc")
174 int err_no_release_subcall(struct __sk_buff *skb)
175 {
176 lookup_no_release(skb);
177 return 0;
178 }
179
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