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
18char _license[] SEC("license") = "GPL";
19
20/* Fill 'tuple' with L3 info, and attempt to find L4. On fail, return NULL. */
21static 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
55SEC("?tc")
56int 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
81SEC("?tc")
82int 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
93SEC("?tc")
94int 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
108SEC("?tc")
109int 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
122SEC("?tc")
123int 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
135SEC("?tc")
136int 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
144SEC("?tc")
145int 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
156SEC("?tc")
157int 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
167void 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
173SEC("?tc")
174int err_no_release_subcall(struct __sk_buff *skb)
175{
176	lookup_no_release(skb);
177	return 0;
178}
179