summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c
blob: 983b7c2333828a511810f3caffbd7a2bba0b5018 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019 Facebook */
#include <linux/stddef.h>
#include <linux/if_ether.h>
#include <linux/ipv6.h>
#include <linux/bpf.h>
#include <linux/tcp.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include <bpf/bpf_tracing.h>

struct sk_buff {
	unsigned int len;
};

__u64 test_result = 0;
SEC("fexit/test_pkt_access")
int BPF_PROG(test_main, struct sk_buff *skb, int ret)
{
	int len;

	__builtin_preserve_access_index(({
		len = skb->len;
	}));
	if (len != 74 || ret != 0)
		return 0;
	test_result = 1;
	return 0;
}

__u64 test_result_subprog1 = 0;
SEC("fexit/test_pkt_access_subprog1")
int BPF_PROG(test_subprog1, struct sk_buff *skb, int ret)
{
	int len;

	__builtin_preserve_access_index(({
		len = skb->len;
	}));
	if (len != 74 || ret != 148)
		return 0;
	test_result_subprog1 = 1;
	return 0;
}

/* Though test_pkt_access_subprog2() is defined in C as:
 * static __attribute__ ((noinline))
 * int test_pkt_access_subprog2(int val, volatile struct __sk_buff *skb)
 * {
 *     return skb->len * val;
 * }
 * llvm optimizations remove 'int val' argument and generate BPF assembly:
 *   r0 = *(u32 *)(r1 + 0)
 *   w0 <<= 1
 *   exit
 * In such case the verifier falls back to conservative and
 * tracing program can access arguments and return value as u64
 * instead of accurate types.
 */
struct args_subprog2 {
	__u64 args[5];
	__u64 ret;
};
__u64 test_result_subprog2 = 0;
SEC("fexit/test_pkt_access_subprog2")
int test_subprog2(struct args_subprog2 *ctx)
{
	struct sk_buff *skb = (void *)ctx->args[0];
	__u64 ret;
	int len;

	bpf_probe_read_kernel(&len, sizeof(len),
			      __builtin_preserve_access_index(&skb->len));

	ret = ctx->ret;
	/* bpf_prog_test_load() loads "test_pkt_access.bpf.o" with
	 * BPF_F_TEST_RND_HI32 which randomizes upper 32 bits after BPF_ALU32
	 * insns. Hence after 'w0 <<= 1' upper bits of $rax are random. That is
	 * expected and correct. Trim them.
	 */
	ret = (__u32) ret;
	if (len != 74 || ret != 148)
		return 0;
	test_result_subprog2 = 1;
	return 0;
}

__u64 test_result_subprog3 = 0;
SEC("fexit/test_pkt_access_subprog3")
int BPF_PROG(test_subprog3, int val, struct sk_buff *skb, int ret)
{
	int len;

	__builtin_preserve_access_index(({
		len = skb->len;
	}));
	if (len != 74 || ret != 74 * val || val != 3)
		return 0;
	test_result_subprog3 = 1;
	return 0;
}

__u64 test_get_skb_len = 0;
SEC("freplace/get_skb_len")
int new_get_skb_len(struct __sk_buff *skb)
{
	int len = skb->len;

	if (len != 74)
		return 0;
	test_get_skb_len = 1;
	return 74; /* original get_skb_len() returns skb->len */
}

__u64 test_get_skb_ifindex = 0;
SEC("freplace/get_skb_ifindex")
int new_get_skb_ifindex(int val, struct __sk_buff *skb, int var)
{
	void *data_end = (void *)(long)skb->data_end;
	void *data = (void *)(long)skb->data;
	struct ipv6hdr ip6, *ip6p;
	int ifindex = skb->ifindex;

	/* check that BPF extension can read packet via direct packet access */
	if (data + 14 + sizeof(ip6) > data_end)
		return 0;
	ip6p = data + 14;

	if (ip6p->nexthdr != 6 || ip6p->payload_len != __bpf_constant_htons(123))
		return 0;

	/* check that legacy packet access helper works too */
	if (bpf_skb_load_bytes(skb, 14, &ip6, sizeof(ip6)) < 0)
		return 0;
	ip6p = &ip6;
	if (ip6p->nexthdr != 6 || ip6p->payload_len != __bpf_constant_htons(123))
		return 0;

	if (ifindex != 1 || val != 3 || var != 1)
		return 0;
	test_get_skb_ifindex = 1;
	return 3; /* original get_skb_ifindex() returns val * ifindex * var */
}

volatile __u64 test_get_constant = 0;
SEC("freplace/get_constant")
int new_get_constant(long val)
{
	if (val != 123)
		return 0;
	test_get_constant = 1;
	return test_get_constant; /* original get_constant() returns val - 122 */
}

__u64 test_pkt_write_access_subprog = 0;
SEC("freplace/test_pkt_write_access_subprog")
int new_test_pkt_write_access_subprog(struct __sk_buff *skb, __u32 off)
{

	void *data = (void *)(long)skb->data;
	void *data_end = (void *)(long)skb->data_end;
	struct tcphdr *tcp;

	if (off > sizeof(struct ethhdr) + sizeof(struct ipv6hdr))
		return -1;

	tcp = data + off;
	if (tcp + 1 > data_end)
		return -1;

	/* make modifications to the packet data */
	tcp->check++;
	tcp->syn = 0;

	test_pkt_write_access_subprog = 1;
	return 0;
}

char _license[] SEC("license") = "GPL";