1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) 2 /* Copyright (c) 2019 Netronome Systems, Inc. */ 3 4 #include <errno.h> 5 #include <fcntl.h> 6 #include <string.h> 7 #include <stdlib.h> 8 #include <unistd.h> 9 #include <net/if.h> 10 #include <sys/utsname.h> 11 12 #include <linux/btf.h> 13 #include <linux/filter.h> 14 #include <linux/kernel.h> 15 #include <linux/version.h> 16 17 #include "bpf.h" 18 #include "libbpf.h" 19 #include "libbpf_internal.h" 20 21 /* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release, 22 * but Ubuntu provides /proc/version_signature file, as described at 23 * https://ubuntu.com/kernel, with an example contents below, which we 24 * can use to get a proper LINUX_VERSION_CODE. 25 * 26 * Ubuntu 5.4.0-12.15-generic 5.4.8 27 * 28 * In the above, 5.4.8 is what kernel is actually expecting, while 29 * uname() call will return 5.4.0 in info.release. 30 */ 31 static __u32 get_ubuntu_kernel_version(void) 32 { 33 const char *ubuntu_kver_file = "/proc/version_signature"; 34 __u32 major, minor, patch; 35 int ret; 36 FILE *f; 37 38 if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) != 0) 39 return 0; 40 41 f = fopen(ubuntu_kver_file, "r"); 42 if (!f) 43 return 0; 44 45 ret = fscanf(f, "%*s %*s %u.%u.%u\n", &major, &minor, &patch); 46 fclose(f); 47 if (ret != 3) 48 return 0; 49 50 return KERNEL_VERSION(major, minor, patch); 51 } 52 53 /* On Debian LINUX_VERSION_CODE doesn't correspond to info.release. 54 * Instead, it is provided in info.version. An example content of 55 * Debian 10 looks like the below. 56 * 57 * utsname::release 4.19.0-22-amd64 58 * utsname::version #1 SMP Debian 4.19.260-1 (2022-09-29) 59 * 60 * In the above, 4.19.260 is what kernel is actually expecting, while 61 * uname() call will return 4.19.0 in info.release. 62 */ 63 static __u32 get_debian_kernel_version(struct utsname *info) 64 { 65 __u32 major, minor, patch; 66 char *p; 67 68 p = strstr(info->version, "Debian "); 69 if (!p) { 70 /* This is not a Debian kernel. */ 71 return 0; 72 } 73 74 if (sscanf(p, "Debian %u.%u.%u", &major, &minor, &patch) != 3) 75 return 0; 76 77 return KERNEL_VERSION(major, minor, patch); 78 } 79 80 __u32 get_kernel_version(void) 81 { 82 __u32 major, minor, patch, version; 83 struct utsname info; 84 85 /* Check if this is an Ubuntu kernel. */ 86 version = get_ubuntu_kernel_version(); 87 if (version != 0) 88 return version; 89 90 uname(&info); 91 92 /* Check if this is a Debian kernel. */ 93 version = get_debian_kernel_version(&info); 94 if (version != 0) 95 return version; 96 97 if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3) 98 return 0; 99 100 return KERNEL_VERSION(major, minor, patch); 101 } 102 103 static int probe_prog_load(enum bpf_prog_type prog_type, 104 const struct bpf_insn *insns, size_t insns_cnt, 105 char *log_buf, size_t log_buf_sz) 106 { 107 LIBBPF_OPTS(bpf_prog_load_opts, opts, 108 .log_buf = log_buf, 109 .log_size = log_buf_sz, 110 .log_level = log_buf ? 1 : 0, 111 ); 112 int fd, err, exp_err = 0; 113 const char *exp_msg = NULL; 114 char buf[4096]; 115 116 switch (prog_type) { 117 case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: 118 opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT; 119 break; 120 case BPF_PROG_TYPE_CGROUP_SOCKOPT: 121 opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT; 122 break; 123 case BPF_PROG_TYPE_SK_LOOKUP: 124 opts.expected_attach_type = BPF_SK_LOOKUP; 125 break; 126 case BPF_PROG_TYPE_KPROBE: 127 opts.kern_version = get_kernel_version(); 128 break; 129 case BPF_PROG_TYPE_LIRC_MODE2: 130 opts.expected_attach_type = BPF_LIRC_MODE2; 131 break; 132 case BPF_PROG_TYPE_TRACING: 133 case BPF_PROG_TYPE_LSM: 134 opts.log_buf = buf; 135 opts.log_size = sizeof(buf); 136 opts.log_level = 1; 137 if (prog_type == BPF_PROG_TYPE_TRACING) 138 opts.expected_attach_type = BPF_TRACE_FENTRY; 139 else 140 opts.expected_attach_type = BPF_MODIFY_RETURN; 141 opts.attach_btf_id = 1; 142 143 exp_err = -EINVAL; 144 exp_msg = "attach_btf_id 1 is not a function"; 145 break; 146 case BPF_PROG_TYPE_EXT: 147 opts.log_buf = buf; 148 opts.log_size = sizeof(buf); 149 opts.log_level = 1; 150 opts.attach_btf_id = 1; 151 152 exp_err = -EINVAL; 153 exp_msg = "Cannot replace kernel functions"; 154 break; 155 case BPF_PROG_TYPE_SYSCALL: 156 opts.prog_flags = BPF_F_SLEEPABLE; 157 break; 158 case BPF_PROG_TYPE_STRUCT_OPS: 159 exp_err = -524; /* -ENOTSUPP */ 160 break; 161 case BPF_PROG_TYPE_UNSPEC: 162 case BPF_PROG_TYPE_SOCKET_FILTER: 163 case BPF_PROG_TYPE_SCHED_CLS: 164 case BPF_PROG_TYPE_SCHED_ACT: 165 case BPF_PROG_TYPE_TRACEPOINT: 166 case BPF_PROG_TYPE_XDP: 167 case BPF_PROG_TYPE_PERF_EVENT: 168 case BPF_PROG_TYPE_CGROUP_SKB: 169 case BPF_PROG_TYPE_CGROUP_SOCK: 170 case BPF_PROG_TYPE_LWT_IN: 171 case BPF_PROG_TYPE_LWT_OUT: 172 case BPF_PROG_TYPE_LWT_XMIT: 173 case BPF_PROG_TYPE_SOCK_OPS: 174 case BPF_PROG_TYPE_SK_SKB: 175 case BPF_PROG_TYPE_CGROUP_DEVICE: 176 case BPF_PROG_TYPE_SK_MSG: 177 case BPF_PROG_TYPE_RAW_TRACEPOINT: 178 case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE: 179 case BPF_PROG_TYPE_LWT_SEG6LOCAL: 180 case BPF_PROG_TYPE_SK_REUSEPORT: 181 case BPF_PROG_TYPE_FLOW_DISSECTOR: 182 case BPF_PROG_TYPE_CGROUP_SYSCTL: 183 break; 184 default: 185 return -EOPNOTSUPP; 186 } 187 188 fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts); 189 err = -errno; 190 if (fd >= 0) 191 close(fd); 192 if (exp_err) { 193 if (fd >= 0 || err != exp_err) 194 return 0; 195 if (exp_msg && !strstr(buf, exp_msg)) 196 return 0; 197 return 1; 198 } 199 return fd >= 0 ? 1 : 0; 200 } 201 202 int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts) 203 { 204 struct bpf_insn insns[] = { 205 BPF_MOV64_IMM(BPF_REG_0, 0), 206 BPF_EXIT_INSN() 207 }; 208 const size_t insn_cnt = ARRAY_SIZE(insns); 209 int ret; 210 211 if (opts) 212 return libbpf_err(-EINVAL); 213 214 ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0); 215 return libbpf_err(ret); 216 } 217 218 int libbpf__load_raw_btf(const char *raw_types, size_t types_len, 219 const char *str_sec, size_t str_len) 220 { 221 struct btf_header hdr = { 222 .magic = BTF_MAGIC, 223 .version = BTF_VERSION, 224 .hdr_len = sizeof(struct btf_header), 225 .type_len = types_len, 226 .str_off = types_len, 227 .str_len = str_len, 228 }; 229 int btf_fd, btf_len; 230 __u8 *raw_btf; 231 232 btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len; 233 raw_btf = malloc(btf_len); 234 if (!raw_btf) 235 return -ENOMEM; 236 237 memcpy(raw_btf, &hdr, sizeof(hdr)); 238 memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len); 239 memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len); 240 241 btf_fd = bpf_btf_load(raw_btf, btf_len, NULL); 242 243 free(raw_btf); 244 return btf_fd; 245 } 246 247 static int load_local_storage_btf(void) 248 { 249 const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l"; 250 /* struct bpf_spin_lock { 251 * int val; 252 * }; 253 * struct val { 254 * int cnt; 255 * struct bpf_spin_lock l; 256 * }; 257 */ 258 __u32 types[] = { 259 /* int */ 260 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ 261 /* struct bpf_spin_lock */ /* [2] */ 262 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4), 263 BTF_MEMBER_ENC(15, 1, 0), /* int val; */ 264 /* struct val */ /* [3] */ 265 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8), 266 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */ 267 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */ 268 }; 269 270 return libbpf__load_raw_btf((char *)types, sizeof(types), 271 strs, sizeof(strs)); 272 } 273 274 static int probe_map_create(enum bpf_map_type map_type) 275 { 276 LIBBPF_OPTS(bpf_map_create_opts, opts); 277 int key_size, value_size, max_entries; 278 __u32 btf_key_type_id = 0, btf_value_type_id = 0; 279 int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0; 280 281 key_size = sizeof(__u32); 282 value_size = sizeof(__u32); 283 max_entries = 1; 284 285 switch (map_type) { 286 case BPF_MAP_TYPE_STACK_TRACE: 287 value_size = sizeof(__u64); 288 break; 289 case BPF_MAP_TYPE_LPM_TRIE: 290 key_size = sizeof(__u64); 291 value_size = sizeof(__u64); 292 opts.map_flags = BPF_F_NO_PREALLOC; 293 break; 294 case BPF_MAP_TYPE_CGROUP_STORAGE: 295 case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: 296 key_size = sizeof(struct bpf_cgroup_storage_key); 297 value_size = sizeof(__u64); 298 max_entries = 0; 299 break; 300 case BPF_MAP_TYPE_QUEUE: 301 case BPF_MAP_TYPE_STACK: 302 key_size = 0; 303 break; 304 case BPF_MAP_TYPE_SK_STORAGE: 305 case BPF_MAP_TYPE_INODE_STORAGE: 306 case BPF_MAP_TYPE_TASK_STORAGE: 307 case BPF_MAP_TYPE_CGRP_STORAGE: 308 btf_key_type_id = 1; 309 btf_value_type_id = 3; 310 value_size = 8; 311 max_entries = 0; 312 opts.map_flags = BPF_F_NO_PREALLOC; 313 btf_fd = load_local_storage_btf(); 314 if (btf_fd < 0) 315 return btf_fd; 316 break; 317 case BPF_MAP_TYPE_RINGBUF: 318 case BPF_MAP_TYPE_USER_RINGBUF: 319 key_size = 0; 320 value_size = 0; 321 max_entries = sysconf(_SC_PAGE_SIZE); 322 break; 323 case BPF_MAP_TYPE_STRUCT_OPS: 324 /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */ 325 opts.btf_vmlinux_value_type_id = 1; 326 exp_err = -524; /* -ENOTSUPP */ 327 break; 328 case BPF_MAP_TYPE_BLOOM_FILTER: 329 key_size = 0; 330 max_entries = 1; 331 break; 332 case BPF_MAP_TYPE_HASH: 333 case BPF_MAP_TYPE_ARRAY: 334 case BPF_MAP_TYPE_PROG_ARRAY: 335 case BPF_MAP_TYPE_PERF_EVENT_ARRAY: 336 case BPF_MAP_TYPE_PERCPU_HASH: 337 case BPF_MAP_TYPE_PERCPU_ARRAY: 338 case BPF_MAP_TYPE_CGROUP_ARRAY: 339 case BPF_MAP_TYPE_LRU_HASH: 340 case BPF_MAP_TYPE_LRU_PERCPU_HASH: 341 case BPF_MAP_TYPE_ARRAY_OF_MAPS: 342 case BPF_MAP_TYPE_HASH_OF_MAPS: 343 case BPF_MAP_TYPE_DEVMAP: 344 case BPF_MAP_TYPE_DEVMAP_HASH: 345 case BPF_MAP_TYPE_SOCKMAP: 346 case BPF_MAP_TYPE_CPUMAP: 347 case BPF_MAP_TYPE_XSKMAP: 348 case BPF_MAP_TYPE_SOCKHASH: 349 case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: 350 break; 351 case BPF_MAP_TYPE_UNSPEC: 352 default: 353 return -EOPNOTSUPP; 354 } 355 356 if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS || 357 map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { 358 fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL, 359 sizeof(__u32), sizeof(__u32), 1, NULL); 360 if (fd_inner < 0) 361 goto cleanup; 362 363 opts.inner_map_fd = fd_inner; 364 } 365 366 if (btf_fd >= 0) { 367 opts.btf_fd = btf_fd; 368 opts.btf_key_type_id = btf_key_type_id; 369 opts.btf_value_type_id = btf_value_type_id; 370 } 371 372 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts); 373 err = -errno; 374 375 cleanup: 376 if (fd >= 0) 377 close(fd); 378 if (fd_inner >= 0) 379 close(fd_inner); 380 if (btf_fd >= 0) 381 close(btf_fd); 382 383 if (exp_err) 384 return fd < 0 && err == exp_err ? 1 : 0; 385 else 386 return fd >= 0 ? 1 : 0; 387 } 388 389 int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts) 390 { 391 int ret; 392 393 if (opts) 394 return libbpf_err(-EINVAL); 395 396 ret = probe_map_create(map_type); 397 return libbpf_err(ret); 398 } 399 400 int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, 401 const void *opts) 402 { 403 struct bpf_insn insns[] = { 404 BPF_EMIT_CALL((__u32)helper_id), 405 BPF_EXIT_INSN(), 406 }; 407 const size_t insn_cnt = ARRAY_SIZE(insns); 408 char buf[4096]; 409 int ret; 410 411 if (opts) 412 return libbpf_err(-EINVAL); 413 414 /* we can't successfully load all prog types to check for BPF helper 415 * support, so bail out with -EOPNOTSUPP error 416 */ 417 switch (prog_type) { 418 case BPF_PROG_TYPE_TRACING: 419 case BPF_PROG_TYPE_EXT: 420 case BPF_PROG_TYPE_LSM: 421 case BPF_PROG_TYPE_STRUCT_OPS: 422 return -EOPNOTSUPP; 423 default: 424 break; 425 } 426 427 buf[0] = '\0'; 428 ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf)); 429 if (ret < 0) 430 return libbpf_err(ret); 431 432 /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id) 433 * at all, it will emit something like "invalid func unknown#181". 434 * If BPF verifier recognizes BPF helper but it's not supported for 435 * given BPF program type, it will emit "unknown func bpf_sys_bpf#166". 436 * In both cases, provided combination of BPF program type and BPF 437 * helper is not supported by the kernel. 438 * In all other cases, probe_prog_load() above will either succeed (e.g., 439 * because BPF helper happens to accept no input arguments or it 440 * accepts one input argument and initial PTR_TO_CTX is fine for 441 * that), or we'll get some more specific BPF verifier error about 442 * some unsatisfied conditions. 443 */ 444 if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func "))) 445 return 0; 446 return 1; /* assume supported */ 447 } 448