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 12 char _license[] SEC("license") = "GPL"; 13 14 struct bpf_map { 15 int id; 16 } __attribute__((preserve_access_index)); 17 18 struct 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 36 struct { 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 43 struct 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 50 struct { 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 62 static inline __u64 ptr_to_u64(const void *ptr) 63 { 64 return (__u64) (unsigned long) ptr; 65 } 66 67 static 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 97 SEC("syscall") 98 int 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 } 159 160 SEC("syscall") 161 int 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; 201 out: 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 } 208