Loading...
1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2021 Facebook */
3#include <linux/stddef.h>
4#include <linux/bpf.h>
5#include <bpf/bpf_helpers.h>
6#include <bpf/bpf_tracing.h>
7#include <../../../tools/include/linux/filter.h>
8#include <linux/btf.h>
9#include <string.h>
10#include <errno.h>
11
12char _license[] SEC("license") = "GPL";
13
14struct bpf_map {
15 int id;
16} __attribute__((preserve_access_index));
17
18struct args {
19 __u64 log_buf;
20 __u32 log_size;
21 int max_entries;
22 int map_fd;
23 int prog_fd;
24 int btf_fd;
25};
26
27#define BTF_INFO_ENC(kind, kind_flag, vlen) \
28 ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
29#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
30#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
31 ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
32#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
33 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
34 BTF_INT_ENC(encoding, bits_offset, bits)
35
36struct {
37 __uint(type, BPF_MAP_TYPE_ARRAY);
38 __type(key, int);
39 __type(value, union bpf_attr);
40 __uint(max_entries, 1);
41} bpf_attr_array SEC(".maps");
42
43struct inner_map_type {
44 __uint(type, BPF_MAP_TYPE_ARRAY);
45 __uint(key_size, 4);
46 __uint(value_size, 4);
47 __uint(max_entries, 1);
48} inner_map SEC(".maps");
49
50struct {
51 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
52 __type(key, int);
53 __type(value, int);
54 __uint(max_entries, 1);
55 __array(values, struct inner_map_type);
56} outer_array_map SEC(".maps") = {
57 .values = {
58 [0] = &inner_map,
59 },
60};
61
62static inline __u64 ptr_to_u64(const void *ptr)
63{
64 return (__u64) (unsigned long) ptr;
65}
66
67static int btf_load(void)
68{
69 struct btf_blob {
70 struct btf_header btf_hdr;
71 __u32 types[8];
72 __u32 str;
73 } raw_btf = {
74 .btf_hdr = {
75 .magic = BTF_MAGIC,
76 .version = BTF_VERSION,
77 .hdr_len = sizeof(struct btf_header),
78 .type_len = sizeof(__u32) * 8,
79 .str_off = sizeof(__u32) * 8,
80 .str_len = sizeof(__u32),
81 },
82 .types = {
83 /* long */
84 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8), /* [1] */
85 /* unsigned long */
86 BTF_TYPE_INT_ENC(0, 0, 0, 64, 8), /* [2] */
87 },
88 };
89 static union bpf_attr btf_load_attr = {
90 .btf_size = sizeof(raw_btf),
91 };
92
93 btf_load_attr.btf = (long)&raw_btf;
94 return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr));
95}
96
97SEC("syscall")
98int load_prog(struct args *ctx)
99{
100 static char license[] = "GPL";
101 static struct bpf_insn insns[] = {
102 BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
103 BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
104 BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
105 BPF_LD_MAP_FD(BPF_REG_1, 0),
106 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
107 BPF_MOV64_IMM(BPF_REG_0, 0),
108 BPF_EXIT_INSN(),
109 };
110 static union bpf_attr map_create_attr = {
111 .map_type = BPF_MAP_TYPE_HASH,
112 .key_size = 8,
113 .value_size = 8,
114 .btf_key_type_id = 1,
115 .btf_value_type_id = 2,
116 };
117 static union bpf_attr map_update_attr = { .map_fd = 1, };
118 static __u64 key = 12;
119 static __u64 value = 34;
120 static union bpf_attr prog_load_attr = {
121 .prog_type = BPF_PROG_TYPE_XDP,
122 .insn_cnt = sizeof(insns) / sizeof(insns[0]),
123 };
124 int ret;
125
126 ret = btf_load();
127 if (ret <= 0)
128 return ret;
129
130 ctx->btf_fd = ret;
131 map_create_attr.max_entries = ctx->max_entries;
132 map_create_attr.btf_fd = ret;
133
134 prog_load_attr.license = ptr_to_u64(license);
135 prog_load_attr.insns = ptr_to_u64(insns);
136 prog_load_attr.log_buf = ctx->log_buf;
137 prog_load_attr.log_size = ctx->log_size;
138 prog_load_attr.log_level = 1;
139
140 ret = bpf_sys_bpf(BPF_MAP_CREATE, &map_create_attr, sizeof(map_create_attr));
141 if (ret <= 0)
142 return ret;
143 ctx->map_fd = ret;
144 insns[3].imm = ret;
145
146 map_update_attr.map_fd = ret;
147 map_update_attr.key = ptr_to_u64(&key);
148 map_update_attr.value = ptr_to_u64(&value);
149 ret = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, &map_update_attr, sizeof(map_update_attr));
150 if (ret < 0)
151 return ret;
152
153 ret = bpf_sys_bpf(BPF_PROG_LOAD, &prog_load_attr, sizeof(prog_load_attr));
154 if (ret <= 0)
155 return ret;
156 ctx->prog_fd = ret;
157 return 1;
158}
159
160SEC("syscall")
161int update_outer_map(void *ctx)
162{
163 int zero = 0, ret = 0, outer_fd = -1, inner_fd = -1, err;
164 const int attr_sz = sizeof(union bpf_attr);
165 union bpf_attr *attr;
166
167 attr = bpf_map_lookup_elem((struct bpf_map *)&bpf_attr_array, &zero);
168 if (!attr)
169 goto out;
170
171 memset(attr, 0, attr_sz);
172 attr->map_id = ((struct bpf_map *)&outer_array_map)->id;
173 outer_fd = bpf_sys_bpf(BPF_MAP_GET_FD_BY_ID, attr, attr_sz);
174 if (outer_fd < 0)
175 goto out;
176
177 memset(attr, 0, attr_sz);
178 attr->map_type = BPF_MAP_TYPE_ARRAY;
179 attr->key_size = 4;
180 attr->value_size = 4;
181 attr->max_entries = 1;
182 inner_fd = bpf_sys_bpf(BPF_MAP_CREATE, attr, attr_sz);
183 if (inner_fd < 0)
184 goto out;
185
186 memset(attr, 0, attr_sz);
187 attr->map_fd = outer_fd;
188 attr->key = ptr_to_u64(&zero);
189 attr->value = ptr_to_u64(&inner_fd);
190 err = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, attr, attr_sz);
191 if (err)
192 goto out;
193
194 memset(attr, 0, attr_sz);
195 attr->map_fd = outer_fd;
196 attr->key = ptr_to_u64(&zero);
197 err = bpf_sys_bpf(BPF_MAP_DELETE_ELEM, attr, attr_sz);
198 if (err)
199 goto out;
200 ret = 1;
201out:
202 if (inner_fd >= 0)
203 bpf_sys_close(inner_fd);
204 if (outer_fd >= 0)
205 bpf_sys_close(outer_fd);
206 return ret;
207}