| 1 | |
| 2 |
|
| 3 |
|
| 4 | #ifdef __KERNEL__
|
| 5 | #include <linux/bpf.h>
|
| 6 | #include <linux/btf.h>
|
| 7 | #include <linux/string.h>
|
| 8 | #include <linux/bpf_verifier.h>
|
| 9 | #include "relo_core.h"
|
| 10 |
|
| 11 | static const char *btf_kind_str(const struct btf_type *t)
|
| 12 | {
|
| 13 | return btf_type_str(t);
|
| 14 | }
|
| 15 |
|
| 16 | static bool is_ldimm64_insn(struct bpf_insn *insn)
|
| 17 | {
|
| 18 | return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
|
| 19 | }
|
| 20 |
|
| 21 | static const struct btf_type *
|
| 22 | skip_mods_and_typedefs(const struct btf *btf, u32 id, u32 *res_id)
|
| 23 | {
|
| 24 | return btf_type_skip_modifiers(btf, id, res_id);
|
| 25 | }
|
| 26 |
|
| 27 | static const char *btf__name_by_offset(const struct btf *btf, u32 offset)
|
| 28 | {
|
| 29 | return btf_name_by_offset(btf, offset);
|
| 30 | }
|
| 31 |
|
| 32 | static s64 btf__resolve_size(const struct btf *btf, u32 type_id)
|
| 33 | {
|
| 34 | const struct btf_type *t;
|
| 35 | int size;
|
| 36 |
|
| 37 | t = btf_type_by_id(btf, type_id);
|
| 38 | t = btf_resolve_size(btf, t, &size);
|
| 39 | if (IS_ERR(t))
|
| 40 | return PTR_ERR(t);
|
| 41 | return size;
|
| 42 | }
|
| 43 |
|
| 44 | enum libbpf_print_level {
|
| 45 | LIBBPF_WARN,
|
| 46 | LIBBPF_INFO,
|
| 47 | LIBBPF_DEBUG,
|
| 48 | };
|
| 49 |
|
| 50 | #undef pr_warn
|
| 51 | #undef pr_info
|
| 52 | #undef pr_debug
|
| 53 | #define pr_warn(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
|
| 54 | #define pr_info(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
|
| 55 | #define pr_debug(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
|
| 56 | #define libbpf_print(level, fmt, ...) bpf_log((void *)prog_name, fmt, ##__VA_ARGS__)
|
| 57 | #else
|
| 58 | #include <stdio.h>
|
| 59 | #include <string.h>
|
| 60 | #include <errno.h>
|
| 61 | #include <ctype.h>
|
| 62 | #include <linux/err.h>
|
| 63 |
|
| 64 | #include "libbpf.h"
|
| 65 | #include "bpf.h"
|
| 66 | #include "btf.h"
|
| 67 | #include "libbpf_internal.h"
|
| 68 | #endif
|
| 69 |
|
| 70 | static bool is_flex_arr(const struct btf *btf,
|
| 71 | const struct bpf_core_accessor *acc,
|
| 72 | const struct btf_array *arr)
|
| 73 | {
|
| 74 | const struct btf_type *t;
|
| 75 |
|
| 76 |
|
| 77 | if (!acc->name || arr->nelems > 0)
|
| 78 | return false;
|
| 79 |
|
| 80 |
|
| 81 | t = btf_type_by_id(btf, acc->type_id);
|
| 82 | return acc->idx == btf_vlen(t) - 1;
|
| 83 | }
|
| 84 |
|
| 85 | static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
|
| 86 | {
|
| 87 | switch (kind) {
|
| 88 | case BPF_CORE_FIELD_BYTE_OFFSET: return "byte_off";
|
| 89 | case BPF_CORE_FIELD_BYTE_SIZE: return "byte_sz";
|
| 90 | case BPF_CORE_FIELD_EXISTS: return "field_exists";
|
| 91 | case BPF_CORE_FIELD_SIGNED: return "signed";
|
| 92 | case BPF_CORE_FIELD_LSHIFT_U64: return "lshift_u64";
|
| 93 | case BPF_CORE_FIELD_RSHIFT_U64: return "rshift_u64";
|
| 94 | case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id";
|
| 95 | case BPF_CORE_TYPE_ID_TARGET: return "target_type_id";
|
| 96 | case BPF_CORE_TYPE_EXISTS: return "type_exists";
|
| 97 | case BPF_CORE_TYPE_MATCHES: return "type_matches";
|
| 98 | case BPF_CORE_TYPE_SIZE: return "type_size";
|
| 99 | case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists";
|
| 100 | case BPF_CORE_ENUMVAL_VALUE: return "enumval_value";
|
| 101 | default: return "unknown";
|
| 102 | }
|
| 103 | }
|
| 104 |
|
| 105 | static bool core_relo_is_field_based(enum bpf_core_relo_kind kind)
|
| 106 | {
|
| 107 | switch (kind) {
|
| 108 | case BPF_CORE_FIELD_BYTE_OFFSET:
|
| 109 | case BPF_CORE_FIELD_BYTE_SIZE:
|
| 110 | case BPF_CORE_FIELD_EXISTS:
|
| 111 | case BPF_CORE_FIELD_SIGNED:
|
| 112 | case BPF_CORE_FIELD_LSHIFT_U64:
|
| 113 | case BPF_CORE_FIELD_RSHIFT_U64:
|
| 114 | return true;
|
| 115 | default:
|
| 116 | return false;
|
| 117 | }
|
| 118 | }
|
| 119 |
|
| 120 | static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
|
| 121 | {
|
| 122 | switch (kind) {
|
| 123 | case BPF_CORE_TYPE_ID_LOCAL:
|
| 124 | case BPF_CORE_TYPE_ID_TARGET:
|
| 125 | case BPF_CORE_TYPE_EXISTS:
|
| 126 | case BPF_CORE_TYPE_MATCHES:
|
| 127 | case BPF_CORE_TYPE_SIZE:
|
| 128 | return true;
|
| 129 | default:
|
| 130 | return false;
|
| 131 | }
|
| 132 | }
|
| 133 |
|
| 134 | static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind)
|
| 135 | {
|
| 136 | switch (kind) {
|
| 137 | case BPF_CORE_ENUMVAL_EXISTS:
|
| 138 | case BPF_CORE_ENUMVAL_VALUE:
|
| 139 | return true;
|
| 140 | default:
|
| 141 | return false;
|
| 142 | }
|
| 143 | }
|
| 144 |
|
| 145 | int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
|
| 146 | const struct btf *targ_btf, __u32 targ_id, int level)
|
| 147 | {
|
| 148 | const struct btf_type *local_type, *targ_type;
|
| 149 | int depth = 32;
|
| 150 |
|
| 151 |
|
| 152 | local_type = btf_type_by_id(local_btf, local_id);
|
| 153 | targ_type = btf_type_by_id(targ_btf, targ_id);
|
| 154 | if (!btf_kind_core_compat(local_type, targ_type))
|
| 155 | return 0;
|
| 156 |
|
| 157 | recur:
|
| 158 | depth--;
|
| 159 | if (depth < 0)
|
| 160 | return -EINVAL;
|
| 161 |
|
| 162 | local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
|
| 163 | targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
| 164 | if (!local_type || !targ_type)
|
| 165 | return -EINVAL;
|
| 166 |
|
| 167 | if (!btf_kind_core_compat(local_type, targ_type))
|
| 168 | return 0;
|
| 169 |
|
| 170 | switch (btf_kind(local_type)) {
|
| 171 | case BTF_KIND_UNKN:
|
| 172 | case BTF_KIND_STRUCT:
|
| 173 | case BTF_KIND_UNION:
|
| 174 | case BTF_KIND_ENUM:
|
| 175 | case BTF_KIND_FWD:
|
| 176 | case BTF_KIND_ENUM64:
|
| 177 | return 1;
|
| 178 | case BTF_KIND_INT:
|
| 179 | |
| 180 | * integers are by default compatible between each other
|
| 181 |
|
| 182 | return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0;
|
| 183 | case BTF_KIND_PTR:
|
| 184 | local_id = local_type->type;
|
| 185 | targ_id = targ_type->type;
|
| 186 | goto recur;
|
| 187 | case BTF_KIND_ARRAY:
|
| 188 | local_id = btf_array(local_type)->type;
|
| 189 | targ_id = btf_array(targ_type)->type;
|
| 190 | goto recur;
|
| 191 | case BTF_KIND_FUNC_PROTO: {
|
| 192 | struct btf_param *local_p = btf_params(local_type);
|
| 193 | struct btf_param *targ_p = btf_params(targ_type);
|
| 194 | __u32 local_vlen = btf_vlen(local_type);
|
| 195 | __u32 targ_vlen = btf_vlen(targ_type);
|
| 196 | int i, err;
|
| 197 |
|
| 198 | if (local_vlen != targ_vlen)
|
| 199 | return 0;
|
| 200 |
|
| 201 | for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
|
| 202 | if (level <= 0)
|
| 203 | return -EINVAL;
|
| 204 |
|
| 205 | skip_mods_and_typedefs(local_btf, local_p->type, &local_id);
|
| 206 | skip_mods_and_typedefs(targ_btf, targ_p->type, &targ_id);
|
| 207 | err = __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
|
| 208 | level - 1);
|
| 209 | if (err <= 0)
|
| 210 | return err;
|
| 211 | }
|
| 212 |
|
| 213 |
|
| 214 | skip_mods_and_typedefs(local_btf, local_type->type, &local_id);
|
| 215 | skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
|
| 216 | goto recur;
|
| 217 | }
|
| 218 | default:
|
| 219 | pr_warn("unexpected kind %s relocated, local [%u], target [%u]\n",
|
| 220 | btf_kind_str(local_type), local_id, targ_id);
|
| 221 | return 0;
|
| 222 | }
|
| 223 | }
|
| 224 |
|
| 225 | |
| 226 | * Turn bpf_core_relo into a low- and high-level spec representation,
|
| 227 | * validating correctness along the way, as well as calculating resulting
|
| 228 | * field bit offset, specified by accessor string. Low-level spec captures
|
| 229 | * every single level of nestedness, including traversing anonymous
|
| 230 | * struct/union members. High-level one only captures semantically meaningful
|
| 231 | * "turning points": named fields and array indicies.
|
| 232 | * E.g., for this case:
|
| 233 | *
|
| 234 | * struct sample {
|
| 235 | * int __unimportant;
|
| 236 | * struct {
|
| 237 | * int __1;
|
| 238 | * int __2;
|
| 239 | * int a[7];
|
| 240 | * };
|
| 241 | * };
|
| 242 | *
|
| 243 | * struct sample *s = ...;
|
| 244 | *
|
| 245 | * int x = &s->a[3]; // access string = '0:1:2:3'
|
| 246 | *
|
| 247 | * Low-level spec has 1:1 mapping with each element of access string (it's
|
| 248 | * just a parsed access string representation): [0, 1, 2, 3].
|
| 249 | *
|
| 250 | * High-level spec will capture only 3 points:
|
| 251 | * - initial zero-index access by pointer (&s->... is the same as &s[0]...);
|
| 252 | * - field 'a' access (corresponds to '2' in low-level spec);
|
| 253 | * - array element #3 access (corresponds to '3' in low-level spec).
|
| 254 | *
|
| 255 | * Type-based relocations (TYPE_EXISTS/TYPE_MATCHES/TYPE_SIZE,
|
| 256 | * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
|
| 257 | * spec and raw_spec are kept empty.
|
| 258 | *
|
| 259 | * Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access
|
| 260 | * string to specify enumerator's value index that need to be relocated.
|
| 261 |
|
| 262 | int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
|
| 263 | const struct bpf_core_relo *relo,
|
| 264 | struct bpf_core_spec *spec)
|
| 265 | {
|
| 266 | int access_idx, parsed_len, i;
|
| 267 | struct bpf_core_accessor *acc;
|
| 268 | const struct btf_type *t;
|
| 269 | const char *name, *spec_str;
|
| 270 | __u32 id, name_off;
|
| 271 | __s64 sz;
|
| 272 |
|
| 273 | spec_str = btf__name_by_offset(btf, relo->access_str_off);
|
| 274 | if (str_is_empty(spec_str) || *spec_str == ':')
|
| 275 | return -EINVAL;
|
| 276 |
|
| 277 | memset(spec, 0, sizeof(*spec));
|
| 278 | spec->btf = btf;
|
| 279 | spec->root_type_id = relo->type_id;
|
| 280 | spec->relo_kind = relo->kind;
|
| 281 |
|
| 282 |
|
| 283 | if (core_relo_is_type_based(relo->kind)) {
|
| 284 | if (strcmp(spec_str, "0"))
|
| 285 | return -EINVAL;
|
| 286 | return 0;
|
| 287 | }
|
| 288 |
|
| 289 |
|
| 290 | while (*spec_str) {
|
| 291 | if (*spec_str == ':')
|
| 292 | ++spec_str;
|
| 293 | if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1)
|
| 294 | return -EINVAL;
|
| 295 | if (access_idx < 0)
|
| 296 | return -EINVAL;
|
| 297 | if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
|
| 298 | return -E2BIG;
|
| 299 | spec_str += parsed_len;
|
| 300 | spec->raw_spec[spec->raw_len++] = access_idx;
|
| 301 | }
|
| 302 |
|
| 303 | if (spec->raw_len == 0)
|
| 304 | return -EINVAL;
|
| 305 |
|
| 306 | t = skip_mods_and_typedefs(btf, relo->type_id, &id);
|
| 307 | if (!t)
|
| 308 | return -EINVAL;
|
| 309 |
|
| 310 | access_idx = spec->raw_spec[0];
|
| 311 | acc = &spec->spec[0];
|
| 312 | acc->type_id = id;
|
| 313 | acc->idx = access_idx;
|
| 314 | spec->len++;
|
| 315 |
|
| 316 | if (core_relo_is_enumval_based(relo->kind)) {
|
| 317 | if (!btf_is_any_enum(t) || spec->raw_len > 1 || access_idx >= btf_vlen(t))
|
| 318 | return -EINVAL;
|
| 319 |
|
| 320 |
|
| 321 | name_off = btf_is_enum(t) ? btf_enum(t)[access_idx].name_off
|
| 322 | : btf_enum64(t)[access_idx].name_off;
|
| 323 | acc->name = btf__name_by_offset(btf, name_off);
|
| 324 | return 0;
|
| 325 | }
|
| 326 |
|
| 327 | if (!core_relo_is_field_based(relo->kind))
|
| 328 | return -EINVAL;
|
| 329 |
|
| 330 | sz = btf__resolve_size(btf, id);
|
| 331 | if (sz < 0)
|
| 332 | return sz;
|
| 333 | spec->bit_offset = access_idx * sz * 8;
|
| 334 |
|
| 335 | for (i = 1; i < spec->raw_len; i++) {
|
| 336 | t = skip_mods_and_typedefs(btf, id, &id);
|
| 337 | if (!t)
|
| 338 | return -EINVAL;
|
| 339 |
|
| 340 | access_idx = spec->raw_spec[i];
|
| 341 | acc = &spec->spec[spec->len];
|
| 342 |
|
| 343 | if (btf_is_composite(t)) {
|
| 344 | const struct btf_member *m;
|
| 345 | __u32 bit_offset;
|
| 346 |
|
| 347 | if (access_idx >= btf_vlen(t))
|
| 348 | return -EINVAL;
|
| 349 |
|
| 350 | bit_offset = btf_member_bit_offset(t, access_idx);
|
| 351 | spec->bit_offset += bit_offset;
|
| 352 |
|
| 353 | m = btf_members(t) + access_idx;
|
| 354 | if (m->name_off) {
|
| 355 | name = btf__name_by_offset(btf, m->name_off);
|
| 356 | if (str_is_empty(name))
|
| 357 | return -EINVAL;
|
| 358 |
|
| 359 | acc->type_id = id;
|
| 360 | acc->idx = access_idx;
|
| 361 | acc->name = name;
|
| 362 | spec->len++;
|
| 363 | }
|
| 364 |
|
| 365 | id = m->type;
|
| 366 | } else if (btf_is_array(t)) {
|
| 367 | const struct btf_array *a = btf_array(t);
|
| 368 | bool flex;
|
| 369 |
|
| 370 | t = skip_mods_and_typedefs(btf, a->type, &id);
|
| 371 | if (!t)
|
| 372 | return -EINVAL;
|
| 373 |
|
| 374 | flex = is_flex_arr(btf, acc - 1, a);
|
| 375 | if (!flex && access_idx >= a->nelems)
|
| 376 | return -EINVAL;
|
| 377 |
|
| 378 | spec->spec[spec->len].type_id = id;
|
| 379 | spec->spec[spec->len].idx = access_idx;
|
| 380 | spec->len++;
|
| 381 |
|
| 382 | sz = btf__resolve_size(btf, id);
|
| 383 | if (sz < 0)
|
| 384 | return sz;
|
| 385 | spec->bit_offset += access_idx * sz * 8;
|
| 386 | } else {
|
| 387 | pr_warn("prog '%s': relo for [%u] %s (at idx %d) captures type [%u] of unexpected kind %s\n",
|
| 388 | prog_name, relo->type_id, spec_str, i, id, btf_kind_str(t));
|
| 389 | return -EINVAL;
|
| 390 | }
|
| 391 | }
|
| 392 |
|
| 393 | return 0;
|
| 394 | }
|
| 395 |
|
| 396 | |
| 397 | * relocation. const/volatile/restrict and typedefs are skipped to ensure we
|
| 398 | * are relocating semantically compatible entities:
|
| 399 | * - any two STRUCTs/UNIONs are compatible and can be mixed;
|
| 400 | * - any two FWDs are compatible, if their names match (modulo flavor suffix);
|
| 401 | * - any two PTRs are always compatible;
|
| 402 | * - for ENUMs, names should be the same (ignoring flavor suffix) or at
|
| 403 | * least one of enums should be anonymous;
|
| 404 | * - for ENUMs, check sizes, names are ignored;
|
| 405 | * - for INT, size and signedness are ignored;
|
| 406 | * - any two FLOATs are always compatible;
|
| 407 | * - for ARRAY, dimensionality is ignored, element types are checked for
|
| 408 | * compatibility recursively;
|
| 409 | * - everything else shouldn't be ever a target of relocation.
|
| 410 | * These rules are not set in stone and probably will be adjusted as we get
|
| 411 | * more experience with using BPF CO-RE relocations.
|
| 412 |
|
| 413 | static int bpf_core_fields_are_compat(const struct btf *local_btf,
|
| 414 | __u32 local_id,
|
| 415 | const struct btf *targ_btf,
|
| 416 | __u32 targ_id)
|
| 417 | {
|
| 418 | const struct btf_type *local_type, *targ_type;
|
| 419 |
|
| 420 | recur:
|
| 421 | local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
|
| 422 | targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
| 423 | if (!local_type || !targ_type)
|
| 424 | return -EINVAL;
|
| 425 |
|
| 426 | if (btf_is_composite(local_type) && btf_is_composite(targ_type))
|
| 427 | return 1;
|
| 428 | if (!btf_kind_core_compat(local_type, targ_type))
|
| 429 | return 0;
|
| 430 |
|
| 431 | switch (btf_kind(local_type)) {
|
| 432 | case BTF_KIND_PTR:
|
| 433 | case BTF_KIND_FLOAT:
|
| 434 | return 1;
|
| 435 | case BTF_KIND_FWD:
|
| 436 | case BTF_KIND_ENUM64:
|
| 437 | case BTF_KIND_ENUM: {
|
| 438 | const char *local_name, *targ_name;
|
| 439 | size_t local_len, targ_len;
|
| 440 |
|
| 441 | local_name = btf__name_by_offset(local_btf,
|
| 442 | local_type->name_off);
|
| 443 | targ_name = btf__name_by_offset(targ_btf, targ_type->name_off);
|
| 444 | local_len = bpf_core_essential_name_len(local_name);
|
| 445 | targ_len = bpf_core_essential_name_len(targ_name);
|
| 446 |
|
| 447 | return local_len == 0 || targ_len == 0 ||
|
| 448 | (local_len == targ_len &&
|
| 449 | strncmp(local_name, targ_name, local_len) == 0);
|
| 450 | }
|
| 451 | case BTF_KIND_INT:
|
| 452 | |
| 453 | * integers are by default compatible between each other
|
| 454 |
|
| 455 | return btf_int_offset(local_type) == 0 &&
|
| 456 | btf_int_offset(targ_type) == 0;
|
| 457 | case BTF_KIND_ARRAY:
|
| 458 | local_id = btf_array(local_type)->type;
|
| 459 | targ_id = btf_array(targ_type)->type;
|
| 460 | goto recur;
|
| 461 | default:
|
| 462 | return 0;
|
| 463 | }
|
| 464 | }
|
| 465 |
|
| 466 | |
| 467 | * Given single high-level named field accessor in local type, find
|
| 468 | * corresponding high-level accessor for a target type. Along the way,
|
| 469 | * maintain low-level spec for target as well. Also keep updating target
|
| 470 | * bit offset.
|
| 471 | *
|
| 472 | * Searching is performed through recursive exhaustive enumeration of all
|
| 473 | * fields of a struct/union. If there are any anonymous (embedded)
|
| 474 | * structs/unions, they are recursively searched as well. If field with
|
| 475 | * desired name is found, check compatibility between local and target types,
|
| 476 | * before returning result.
|
| 477 | *
|
| 478 | * 1 is returned, if field is found.
|
| 479 | * 0 is returned if no compatible field is found.
|
| 480 | * <0 is returned on error.
|
| 481 |
|
| 482 | static int bpf_core_match_member(const struct btf *local_btf,
|
| 483 | const struct bpf_core_accessor *local_acc,
|
| 484 | const struct btf *targ_btf,
|
| 485 | __u32 targ_id,
|
| 486 | struct bpf_core_spec *spec,
|
| 487 | __u32 *next_targ_id)
|
| 488 | {
|
| 489 | const struct btf_type *local_type, *targ_type;
|
| 490 | const struct btf_member *local_member, *m;
|
| 491 | const char *local_name, *targ_name;
|
| 492 | __u32 local_id;
|
| 493 | int i, n, found;
|
| 494 |
|
| 495 | targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
| 496 | if (!targ_type)
|
| 497 | return -EINVAL;
|
| 498 | if (!btf_is_composite(targ_type))
|
| 499 | return 0;
|
| 500 |
|
| 501 | local_id = local_acc->type_id;
|
| 502 | local_type = btf_type_by_id(local_btf, local_id);
|
| 503 | local_member = btf_members(local_type) + local_acc->idx;
|
| 504 | local_name = btf__name_by_offset(local_btf, local_member->name_off);
|
| 505 |
|
| 506 | n = btf_vlen(targ_type);
|
| 507 | m = btf_members(targ_type);
|
| 508 | for (i = 0; i < n; i++, m++) {
|
| 509 | __u32 bit_offset;
|
| 510 |
|
| 511 | bit_offset = btf_member_bit_offset(targ_type, i);
|
| 512 |
|
| 513 |
|
| 514 | if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
|
| 515 | return -E2BIG;
|
| 516 |
|
| 517 |
|
| 518 | spec->bit_offset += bit_offset;
|
| 519 | spec->raw_spec[spec->raw_len++] = i;
|
| 520 |
|
| 521 | targ_name = btf__name_by_offset(targ_btf, m->name_off);
|
| 522 | if (str_is_empty(targ_name)) {
|
| 523 |
|
| 524 | found = bpf_core_match_member(local_btf, local_acc,
|
| 525 | targ_btf, m->type,
|
| 526 | spec, next_targ_id);
|
| 527 | if (found)
|
| 528 | return found;
|
| 529 | } else if (strcmp(local_name, targ_name) == 0) {
|
| 530 |
|
| 531 | struct bpf_core_accessor *targ_acc;
|
| 532 |
|
| 533 | targ_acc = &spec->spec[spec->len++];
|
| 534 | targ_acc->type_id = targ_id;
|
| 535 | targ_acc->idx = i;
|
| 536 | targ_acc->name = targ_name;
|
| 537 |
|
| 538 | *next_targ_id = m->type;
|
| 539 | found = bpf_core_fields_are_compat(local_btf,
|
| 540 | local_member->type,
|
| 541 | targ_btf, m->type);
|
| 542 | if (!found)
|
| 543 | spec->len--;
|
| 544 | return found;
|
| 545 | }
|
| 546 |
|
| 547 | spec->bit_offset -= bit_offset;
|
| 548 | spec->raw_len--;
|
| 549 | }
|
| 550 |
|
| 551 | return 0;
|
| 552 | }
|
| 553 |
|
| 554 | |
| 555 | * Try to match local spec to a target type and, if successful, produce full
|
| 556 | * target spec (high-level, low-level + bit offset).
|
| 557 |
|
| 558 | static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
|
| 559 | const struct btf *targ_btf, __u32 targ_id,
|
| 560 | struct bpf_core_spec *targ_spec)
|
| 561 | {
|
| 562 | const struct btf_type *targ_type;
|
| 563 | const struct bpf_core_accessor *local_acc;
|
| 564 | struct bpf_core_accessor *targ_acc;
|
| 565 | int i, sz, matched;
|
| 566 | __u32 name_off;
|
| 567 |
|
| 568 | memset(targ_spec, 0, sizeof(*targ_spec));
|
| 569 | targ_spec->btf = targ_btf;
|
| 570 | targ_spec->root_type_id = targ_id;
|
| 571 | targ_spec->relo_kind = local_spec->relo_kind;
|
| 572 |
|
| 573 | if (core_relo_is_type_based(local_spec->relo_kind)) {
|
| 574 | if (local_spec->relo_kind == BPF_CORE_TYPE_MATCHES)
|
| 575 | return bpf_core_types_match(local_spec->btf,
|
| 576 | local_spec->root_type_id,
|
| 577 | targ_btf, targ_id);
|
| 578 | else
|
| 579 | return bpf_core_types_are_compat(local_spec->btf,
|
| 580 | local_spec->root_type_id,
|
| 581 | targ_btf, targ_id);
|
| 582 | }
|
| 583 |
|
| 584 | local_acc = &local_spec->spec[0];
|
| 585 | targ_acc = &targ_spec->spec[0];
|
| 586 |
|
| 587 | if (core_relo_is_enumval_based(local_spec->relo_kind)) {
|
| 588 | size_t local_essent_len, targ_essent_len;
|
| 589 | const char *targ_name;
|
| 590 |
|
| 591 |
|
| 592 | targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id);
|
| 593 | if (!btf_is_any_enum(targ_type))
|
| 594 | return 0;
|
| 595 |
|
| 596 | local_essent_len = bpf_core_essential_name_len(local_acc->name);
|
| 597 |
|
| 598 | for (i = 0; i < btf_vlen(targ_type); i++) {
|
| 599 | if (btf_is_enum(targ_type))
|
| 600 | name_off = btf_enum(targ_type)[i].name_off;
|
| 601 | else
|
| 602 | name_off = btf_enum64(targ_type)[i].name_off;
|
| 603 |
|
| 604 | targ_name = btf__name_by_offset(targ_spec->btf, name_off);
|
| 605 | targ_essent_len = bpf_core_essential_name_len(targ_name);
|
| 606 | if (targ_essent_len != local_essent_len)
|
| 607 | continue;
|
| 608 | if (strncmp(local_acc->name, targ_name, local_essent_len) == 0) {
|
| 609 | targ_acc->type_id = targ_id;
|
| 610 | targ_acc->idx = i;
|
| 611 | targ_acc->name = targ_name;
|
| 612 | targ_spec->len++;
|
| 613 | targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
|
| 614 | targ_spec->raw_len++;
|
| 615 | return 1;
|
| 616 | }
|
| 617 | }
|
| 618 | return 0;
|
| 619 | }
|
| 620 |
|
| 621 | if (!core_relo_is_field_based(local_spec->relo_kind))
|
| 622 | return -EINVAL;
|
| 623 |
|
| 624 | for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) {
|
| 625 | targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id,
|
| 626 | &targ_id);
|
| 627 | if (!targ_type)
|
| 628 | return -EINVAL;
|
| 629 |
|
| 630 | if (local_acc->name) {
|
| 631 | matched = bpf_core_match_member(local_spec->btf,
|
| 632 | local_acc,
|
| 633 | targ_btf, targ_id,
|
| 634 | targ_spec, &targ_id);
|
| 635 | if (matched <= 0)
|
| 636 | return matched;
|
| 637 | } else {
|
| 638 | |
| 639 | * type (because it's the original struct), for others
|
| 640 | * we should find array element type first
|
| 641 |
|
| 642 | if (i > 0) {
|
| 643 | const struct btf_array *a;
|
| 644 | bool flex;
|
| 645 |
|
| 646 | if (!btf_is_array(targ_type))
|
| 647 | return 0;
|
| 648 |
|
| 649 | a = btf_array(targ_type);
|
| 650 | flex = is_flex_arr(targ_btf, targ_acc - 1, a);
|
| 651 | if (!flex && local_acc->idx >= a->nelems)
|
| 652 | return 0;
|
| 653 | if (!skip_mods_and_typedefs(targ_btf, a->type,
|
| 654 | &targ_id))
|
| 655 | return -EINVAL;
|
| 656 | }
|
| 657 |
|
| 658 |
|
| 659 | if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
|
| 660 | return -E2BIG;
|
| 661 |
|
| 662 | targ_acc->type_id = targ_id;
|
| 663 | targ_acc->idx = local_acc->idx;
|
| 664 | targ_acc->name = NULL;
|
| 665 | targ_spec->len++;
|
| 666 | targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
|
| 667 | targ_spec->raw_len++;
|
| 668 |
|
| 669 | sz = btf__resolve_size(targ_btf, targ_id);
|
| 670 | if (sz < 0)
|
| 671 | return sz;
|
| 672 | targ_spec->bit_offset += local_acc->idx * sz * 8;
|
| 673 | }
|
| 674 | }
|
| 675 |
|
| 676 | return 1;
|
| 677 | }
|
| 678 |
|
| 679 | static int bpf_core_calc_field_relo(const char *prog_name,
|
| 680 | const struct bpf_core_relo *relo,
|
| 681 | const struct bpf_core_spec *spec,
|
| 682 | __u64 *val, __u32 *field_sz, __u32 *type_id,
|
| 683 | bool *validate)
|
| 684 | {
|
| 685 | const struct bpf_core_accessor *acc;
|
| 686 | const struct btf_type *t;
|
| 687 | __u32 byte_off, byte_sz, bit_off, bit_sz, field_type_id, elem_id;
|
| 688 | const struct btf_member *m;
|
| 689 | const struct btf_type *mt;
|
| 690 | bool bitfield;
|
| 691 | __s64 sz;
|
| 692 |
|
| 693 | *field_sz = 0;
|
| 694 |
|
| 695 | if (relo->kind == BPF_CORE_FIELD_EXISTS) {
|
| 696 | *val = spec ? 1 : 0;
|
| 697 | return 0;
|
| 698 | }
|
| 699 |
|
| 700 | if (!spec)
|
| 701 | return -EUCLEAN;
|
| 702 |
|
| 703 | acc = &spec->spec[spec->len - 1];
|
| 704 | t = btf_type_by_id(spec->btf, acc->type_id);
|
| 705 |
|
| 706 |
|
| 707 | if (!acc->name) {
|
| 708 | if (relo->kind == BPF_CORE_FIELD_BYTE_OFFSET) {
|
| 709 | *val = spec->bit_offset / 8;
|
| 710 | |
| 711 | * note, for arrays we care about individual element
|
| 712 | * sizes, not the overall array size
|
| 713 |
|
| 714 | t = skip_mods_and_typedefs(spec->btf, acc->type_id, &elem_id);
|
| 715 | while (btf_is_array(t))
|
| 716 | t = skip_mods_and_typedefs(spec->btf, btf_array(t)->type, &elem_id);
|
| 717 | sz = btf__resolve_size(spec->btf, elem_id);
|
| 718 | if (sz < 0)
|
| 719 | return -EINVAL;
|
| 720 | *field_sz = sz;
|
| 721 | *type_id = acc->type_id;
|
| 722 | } else if (relo->kind == BPF_CORE_FIELD_BYTE_SIZE) {
|
| 723 | sz = btf__resolve_size(spec->btf, acc->type_id);
|
| 724 | if (sz < 0)
|
| 725 | return -EINVAL;
|
| 726 | *val = sz;
|
| 727 | } else {
|
| 728 | pr_warn("prog '%s': relo %u at insn #%u can't be applied to array access\n",
|
| 729 | prog_name, relo->kind, relo->insn_off / 8);
|
| 730 | return -EINVAL;
|
| 731 | }
|
| 732 | if (validate)
|
| 733 | *validate = true;
|
| 734 | return 0;
|
| 735 | }
|
| 736 |
|
| 737 | m = btf_members(t) + acc->idx;
|
| 738 | mt = skip_mods_and_typedefs(spec->btf, m->type, &field_type_id);
|
| 739 | bit_off = spec->bit_offset;
|
| 740 | bit_sz = btf_member_bitfield_size(t, acc->idx);
|
| 741 |
|
| 742 | bitfield = bit_sz > 0;
|
| 743 | if (bitfield) {
|
| 744 | byte_sz = mt->size;
|
| 745 | byte_off = bit_off / 8 / byte_sz * byte_sz;
|
| 746 |
|
| 747 | while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) {
|
| 748 | if (byte_sz >= 8) {
|
| 749 |
|
| 750 | pr_warn("prog '%s': relo %u at insn #%u can't be satisfied for bitfield\n",
|
| 751 | prog_name, relo->kind, relo->insn_off / 8);
|
| 752 | return -E2BIG;
|
| 753 | }
|
| 754 | byte_sz *= 2;
|
| 755 | byte_off = bit_off / 8 / byte_sz * byte_sz;
|
| 756 | }
|
| 757 | } else {
|
| 758 | sz = btf__resolve_size(spec->btf, field_type_id);
|
| 759 | if (sz < 0)
|
| 760 | return -EINVAL;
|
| 761 | byte_sz = sz;
|
| 762 | byte_off = spec->bit_offset / 8;
|
| 763 | bit_sz = byte_sz * 8;
|
| 764 | }
|
| 765 |
|
| 766 | |
| 767 | * might disagree with compiler, so turn off validation of expected
|
| 768 | * value, except for signedness
|
| 769 |
|
| 770 | if (validate)
|
| 771 | *validate = !bitfield;
|
| 772 |
|
| 773 | switch (relo->kind) {
|
| 774 | case BPF_CORE_FIELD_BYTE_OFFSET:
|
| 775 | *val = byte_off;
|
| 776 | if (!bitfield) {
|
| 777 | |
| 778 | * note, for arrays we care about individual element
|
| 779 | * sizes, not the overall array size
|
| 780 |
|
| 781 | t = skip_mods_and_typedefs(spec->btf, field_type_id, &elem_id);
|
| 782 | while (btf_is_array(t))
|
| 783 | t = skip_mods_and_typedefs(spec->btf, btf_array(t)->type, &elem_id);
|
| 784 | sz = btf__resolve_size(spec->btf, elem_id);
|
| 785 | if (sz < 0)
|
| 786 | return -EINVAL;
|
| 787 | *field_sz = sz;
|
| 788 | *type_id = field_type_id;
|
| 789 | }
|
| 790 | break;
|
| 791 | case BPF_CORE_FIELD_BYTE_SIZE:
|
| 792 | *val = byte_sz;
|
| 793 | break;
|
| 794 | case BPF_CORE_FIELD_SIGNED:
|
| 795 | *val = (btf_is_any_enum(mt) && BTF_INFO_KFLAG(mt->info)) ||
|
| 796 | (btf_is_int(mt) && (btf_int_encoding(mt) & BTF_INT_SIGNED));
|
| 797 | if (validate)
|
| 798 | *validate = true;
|
| 799 | break;
|
| 800 | case BPF_CORE_FIELD_LSHIFT_U64:
|
| 801 | #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
|
| 802 | *val = 64 - (bit_off + bit_sz - byte_off * 8);
|
| 803 | #else
|
| 804 | *val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8);
|
| 805 | #endif
|
| 806 | break;
|
| 807 | case BPF_CORE_FIELD_RSHIFT_U64:
|
| 808 | *val = 64 - bit_sz;
|
| 809 | if (validate)
|
| 810 | *validate = true;
|
| 811 | break;
|
| 812 | case BPF_CORE_FIELD_EXISTS:
|
| 813 | default:
|
| 814 | return -EOPNOTSUPP;
|
| 815 | }
|
| 816 |
|
| 817 | return 0;
|
| 818 | }
|
| 819 |
|
| 820 | static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
|
| 821 | const struct bpf_core_spec *spec,
|
| 822 | __u64 *val, bool *validate)
|
| 823 | {
|
| 824 | __s64 sz;
|
| 825 |
|
| 826 |
|
| 827 | if (validate)
|
| 828 | *validate = true;
|
| 829 |
|
| 830 |
|
| 831 | if (!spec) {
|
| 832 | *val = 0;
|
| 833 | return 0;
|
| 834 | }
|
| 835 |
|
| 836 | switch (relo->kind) {
|
| 837 | case BPF_CORE_TYPE_ID_TARGET:
|
| 838 | *val = spec->root_type_id;
|
| 839 | |
| 840 | * so enforcing it is pointless
|
| 841 |
|
| 842 | if (validate)
|
| 843 | *validate = false;
|
| 844 | break;
|
| 845 | case BPF_CORE_TYPE_EXISTS:
|
| 846 | case BPF_CORE_TYPE_MATCHES:
|
| 847 | *val = 1;
|
| 848 | break;
|
| 849 | case BPF_CORE_TYPE_SIZE:
|
| 850 | sz = btf__resolve_size(spec->btf, spec->root_type_id);
|
| 851 | if (sz < 0)
|
| 852 | return -EINVAL;
|
| 853 | *val = sz;
|
| 854 | break;
|
| 855 | case BPF_CORE_TYPE_ID_LOCAL:
|
| 856 |
|
| 857 | default:
|
| 858 | return -EOPNOTSUPP;
|
| 859 | }
|
| 860 |
|
| 861 | return 0;
|
| 862 | }
|
| 863 |
|
| 864 | static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo,
|
| 865 | const struct bpf_core_spec *spec,
|
| 866 | __u64 *val)
|
| 867 | {
|
| 868 | const struct btf_type *t;
|
| 869 |
|
| 870 | switch (relo->kind) {
|
| 871 | case BPF_CORE_ENUMVAL_EXISTS:
|
| 872 | *val = spec ? 1 : 0;
|
| 873 | break;
|
| 874 | case BPF_CORE_ENUMVAL_VALUE:
|
| 875 | if (!spec)
|
| 876 | return -EUCLEAN;
|
| 877 | t = btf_type_by_id(spec->btf, spec->spec[0].type_id);
|
| 878 | if (btf_is_enum(t))
|
| 879 | *val = btf_enum(t)[spec->spec[0].idx].val;
|
| 880 | else
|
| 881 | *val = btf_enum64_value(btf_enum64(t) + spec->spec[0].idx);
|
| 882 | break;
|
| 883 | default:
|
| 884 | return -EOPNOTSUPP;
|
| 885 | }
|
| 886 |
|
| 887 | return 0;
|
| 888 | }
|
| 889 |
|
| 890 | |
| 891 | * specs and relocation kind. These values are calculated for each candidate.
|
| 892 | * If there are multiple candidates, resulting values should all be consistent
|
| 893 | * with each other. Otherwise, libbpf will refuse to proceed due to ambiguity.
|
| 894 | * If instruction has to be poisoned, *poison will be set to true.
|
| 895 |
|
| 896 | static int bpf_core_calc_relo(const char *prog_name,
|
| 897 | const struct bpf_core_relo *relo,
|
| 898 | int relo_idx,
|
| 899 | const struct bpf_core_spec *local_spec,
|
| 900 | const struct bpf_core_spec *targ_spec,
|
| 901 | struct bpf_core_relo_res *res)
|
| 902 | {
|
| 903 | int err = -EOPNOTSUPP;
|
| 904 |
|
| 905 | res->orig_val = 0;
|
| 906 | res->new_val = 0;
|
| 907 | res->poison = false;
|
| 908 | res->validate = true;
|
| 909 | res->fail_memsz_adjust = false;
|
| 910 | res->orig_sz = res->new_sz = 0;
|
| 911 | res->orig_type_id = res->new_type_id = 0;
|
| 912 |
|
| 913 | if (core_relo_is_field_based(relo->kind)) {
|
| 914 | err = bpf_core_calc_field_relo(prog_name, relo, local_spec,
|
| 915 | &res->orig_val, &res->orig_sz,
|
| 916 | &res->orig_type_id, &res->validate);
|
| 917 | err = err ?: bpf_core_calc_field_relo(prog_name, relo, targ_spec,
|
| 918 | &res->new_val, &res->new_sz,
|
| 919 | &res->new_type_id, NULL);
|
| 920 | if (err)
|
| 921 | goto done;
|
| 922 | |
| 923 | * Adjustments are performed only if original and new memory
|
| 924 | * sizes differ.
|
| 925 |
|
| 926 | res->fail_memsz_adjust = false;
|
| 927 | if (res->orig_sz != res->new_sz) {
|
| 928 | const struct btf_type *orig_t, *new_t;
|
| 929 |
|
| 930 | orig_t = btf_type_by_id(local_spec->btf, res->orig_type_id);
|
| 931 | new_t = btf_type_by_id(targ_spec->btf, res->new_type_id);
|
| 932 |
|
| 933 | |
| 934 | * adjust load/store's mem size:
|
| 935 | * - reading a 32-bit kernel pointer, while on BPF
|
| 936 | * size pointers are always 64-bit; in this case
|
| 937 | * it's safe to "downsize" instruction size due to
|
| 938 | * pointer being treated as unsigned integer with
|
| 939 | * zero-extended upper 32-bits;
|
| 940 | * - reading unsigned integers, again due to
|
| 941 | * zero-extension is preserving the value correctly.
|
| 942 | *
|
| 943 | * In all other cases it's incorrect to attempt to
|
| 944 | * load/store field because read value will be
|
| 945 | * incorrect, so we poison relocated instruction.
|
| 946 |
|
| 947 | if (btf_is_ptr(orig_t) && btf_is_ptr(new_t))
|
| 948 | goto done;
|
| 949 | if (btf_is_int(orig_t) && btf_is_int(new_t) &&
|
| 950 | btf_int_encoding(orig_t) != BTF_INT_SIGNED &&
|
| 951 | btf_int_encoding(new_t) != BTF_INT_SIGNED)
|
| 952 | goto done;
|
| 953 |
|
| 954 | |
| 955 | * only be checked for LDX/STX/ST insns
|
| 956 |
|
| 957 | res->fail_memsz_adjust = true;
|
| 958 | }
|
| 959 | } else if (core_relo_is_type_based(relo->kind)) {
|
| 960 | err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val, &res->validate);
|
| 961 | err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val, NULL);
|
| 962 | } else if (core_relo_is_enumval_based(relo->kind)) {
|
| 963 | err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val);
|
| 964 | err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val);
|
| 965 | }
|
| 966 |
|
| 967 | done:
|
| 968 | if (err == -EUCLEAN) {
|
| 969 |
|
| 970 | res->poison = true;
|
| 971 | err = 0;
|
| 972 | } else if (err == -EOPNOTSUPP) {
|
| 973 |
|
| 974 | pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%u) at insn #%u\n",
|
| 975 | prog_name, relo_idx, core_relo_kind_str(relo->kind),
|
| 976 | relo->kind, relo->insn_off / 8);
|
| 977 | }
|
| 978 |
|
| 979 | return err;
|
| 980 | }
|
| 981 |
|
| 982 | |
| 983 | * Turn instruction for which CO-RE relocation failed into invalid one with
|
| 984 | * distinct signature.
|
| 985 |
|
| 986 | static int bpf_core_poison_insn(const char *prog_name, int relo_idx,
|
| 987 | struct bpf_insn *insn, int insn_idx)
|
| 988 | {
|
| 989 | int insn_cnt = is_ldimm64_insn(insn) ? 2 : 1;
|
| 990 | int i;
|
| 991 |
|
| 992 | for (i = 0; i < insn_cnt; i++) {
|
| 993 | pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n",
|
| 994 | prog_name, relo_idx, insn_idx + i);
|
| 995 | insn[i].code = BPF_JMP | BPF_CALL;
|
| 996 | insn[i].dst_reg = 0;
|
| 997 | insn[i].src_reg = 0;
|
| 998 | insn[i].off = 0;
|
| 999 | |
| 1000 | * If this instruction is reachable (not dead code), the verifier
|
| 1001 | * will complain with "invalid func unknown#195896080".
|
| 1002 |
|
| 1003 | insn[i].imm = 195896080;
|
| 1004 | }
|
| 1005 |
|
| 1006 | return 0;
|
| 1007 | }
|
| 1008 |
|
| 1009 | static int insn_bpf_size_to_bytes(struct bpf_insn *insn)
|
| 1010 | {
|
| 1011 | switch (BPF_SIZE(insn->code)) {
|
| 1012 | case BPF_DW: return 8;
|
| 1013 | case BPF_W: return 4;
|
| 1014 | case BPF_H: return 2;
|
| 1015 | case BPF_B: return 1;
|
| 1016 | default: return -1;
|
| 1017 | }
|
| 1018 | }
|
| 1019 |
|
| 1020 | static int insn_bytes_to_bpf_size(__u32 sz)
|
| 1021 | {
|
| 1022 | switch (sz) {
|
| 1023 | case 8: return BPF_DW;
|
| 1024 | case 4: return BPF_W;
|
| 1025 | case 2: return BPF_H;
|
| 1026 | case 1: return BPF_B;
|
| 1027 | default: return -1;
|
| 1028 | }
|
| 1029 | }
|
| 1030 |
|
| 1031 | |
| 1032 | * Patch relocatable BPF instruction.
|
| 1033 | *
|
| 1034 | * Patched value is determined by relocation kind and target specification.
|
| 1035 | * For existence relocations target spec will be NULL if field/type is not found.
|
| 1036 | * Expected insn->imm value is determined using relocation kind and local
|
| 1037 | * spec, and is checked before patching instruction. If actual insn->imm value
|
| 1038 | * is wrong, bail out with error.
|
| 1039 | *
|
| 1040 | * Currently supported classes of BPF instruction are:
|
| 1041 | * 1. rX = <imm> (assignment with immediate operand);
|
| 1042 | * 2. rX += <imm> (arithmetic operations with immediate operand);
|
| 1043 | * 3. rX = <imm64> (load with 64-bit immediate value);
|
| 1044 | * 4. rX = *(T *)(rY + <off>), where T is one of {u8, u16, u32, u64};
|
| 1045 | * 5. *(T *)(rX + <off>) = rY, where T is one of {u8, u16, u32, u64};
|
| 1046 | * 6. *(T *)(rX + <off>) = <imm>, where T is one of {u8, u16, u32, u64}.
|
| 1047 |
|
| 1048 | int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
|
| 1049 | int insn_idx, const struct bpf_core_relo *relo,
|
| 1050 | int relo_idx, const struct bpf_core_relo_res *res)
|
| 1051 | {
|
| 1052 | __u64 orig_val, new_val;
|
| 1053 | __u8 class;
|
| 1054 |
|
| 1055 | class = BPF_CLASS(insn->code);
|
| 1056 |
|
| 1057 | orig_val = res->orig_val;
|
| 1058 | new_val = res->new_val;
|
| 1059 |
|
| 1060 | switch (class) {
|
| 1061 | case BPF_ALU:
|
| 1062 | case BPF_ALU64:
|
| 1063 | if (BPF_SRC(insn->code) != BPF_K)
|
| 1064 | goto bad_insn;
|
| 1065 | if (res->poison)
|
| 1066 | return bpf_core_poison_insn(prog_name, relo_idx, insn, insn_idx);
|
| 1067 | if (res->validate && insn->imm != orig_val) {
|
| 1068 | pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %d, exp %llu -> %llu\n",
|
| 1069 | prog_name, relo_idx,
|
| 1070 | insn_idx, insn->imm, (unsigned long long)orig_val,
|
| 1071 | (unsigned long long)new_val);
|
| 1072 | return -EINVAL;
|
| 1073 | }
|
| 1074 | orig_val = insn->imm;
|
| 1075 | insn->imm = new_val;
|
| 1076 | pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %llu -> %llu\n",
|
| 1077 | prog_name, relo_idx, insn_idx,
|
| 1078 | (unsigned long long)orig_val, (unsigned long long)new_val);
|
| 1079 | break;
|
| 1080 | case BPF_LDX:
|
| 1081 | case BPF_ST:
|
| 1082 | case BPF_STX:
|
| 1083 | if (res->poison)
|
| 1084 | return bpf_core_poison_insn(prog_name, relo_idx, insn, insn_idx);
|
| 1085 | if (res->validate && insn->off != orig_val) {
|
| 1086 | pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %d, exp %llu -> %llu\n",
|
| 1087 | prog_name, relo_idx, insn_idx, insn->off, (unsigned long long)orig_val,
|
| 1088 | (unsigned long long)new_val);
|
| 1089 | return -EINVAL;
|
| 1090 | }
|
| 1091 | if (new_val > SHRT_MAX) {
|
| 1092 | pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %llu\n",
|
| 1093 | prog_name, relo_idx, insn_idx, (unsigned long long)new_val);
|
| 1094 | return -ERANGE;
|
| 1095 | }
|
| 1096 | if (res->fail_memsz_adjust) {
|
| 1097 | pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) accesses field incorrectly. "
|
| 1098 | "Make sure you are accessing pointers, unsigned integers, or fields of matching type and size.\n",
|
| 1099 | prog_name, relo_idx, insn_idx);
|
| 1100 | return bpf_core_poison_insn(prog_name, relo_idx, insn, insn_idx);
|
| 1101 | }
|
| 1102 |
|
| 1103 | orig_val = insn->off;
|
| 1104 | insn->off = new_val;
|
| 1105 | pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %llu -> %llu\n",
|
| 1106 | prog_name, relo_idx, insn_idx, (unsigned long long)orig_val,
|
| 1107 | (unsigned long long)new_val);
|
| 1108 |
|
| 1109 | if (res->new_sz != res->orig_sz) {
|
| 1110 | int insn_bytes_sz, insn_bpf_sz;
|
| 1111 |
|
| 1112 | insn_bytes_sz = insn_bpf_size_to_bytes(insn);
|
| 1113 | if (insn_bytes_sz != res->orig_sz) {
|
| 1114 | pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) unexpected mem size: got %d, exp %u\n",
|
| 1115 | prog_name, relo_idx, insn_idx, insn_bytes_sz, res->orig_sz);
|
| 1116 | return -EINVAL;
|
| 1117 | }
|
| 1118 |
|
| 1119 | insn_bpf_sz = insn_bytes_to_bpf_size(res->new_sz);
|
| 1120 | if (insn_bpf_sz < 0) {
|
| 1121 | pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) invalid new mem size: %u\n",
|
| 1122 | prog_name, relo_idx, insn_idx, res->new_sz);
|
| 1123 | return -EINVAL;
|
| 1124 | }
|
| 1125 |
|
| 1126 | insn->code = BPF_MODE(insn->code) | insn_bpf_sz | BPF_CLASS(insn->code);
|
| 1127 | pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) mem_sz %u -> %u\n",
|
| 1128 | prog_name, relo_idx, insn_idx, res->orig_sz, res->new_sz);
|
| 1129 | }
|
| 1130 | break;
|
| 1131 | case BPF_LD: {
|
| 1132 | __u64 imm;
|
| 1133 |
|
| 1134 | if (!is_ldimm64_insn(insn) ||
|
| 1135 | insn[0].src_reg != 0 || insn[0].off != 0 ||
|
| 1136 | insn[1].code != 0 || insn[1].dst_reg != 0 ||
|
| 1137 | insn[1].src_reg != 0 || insn[1].off != 0) {
|
| 1138 | pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
|
| 1139 | prog_name, relo_idx, insn_idx);
|
| 1140 | return -EINVAL;
|
| 1141 | }
|
| 1142 |
|
| 1143 | if (res->poison)
|
| 1144 | return bpf_core_poison_insn(prog_name, relo_idx, insn, insn_idx);
|
| 1145 |
|
| 1146 | imm = (__u32)insn[0].imm | ((__u64)insn[1].imm << 32);
|
| 1147 | if (res->validate && imm != orig_val) {
|
| 1148 | pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %llu -> %llu\n",
|
| 1149 | prog_name, relo_idx,
|
| 1150 | insn_idx, (unsigned long long)imm,
|
| 1151 | (unsigned long long)orig_val, (unsigned long long)new_val);
|
| 1152 | return -EINVAL;
|
| 1153 | }
|
| 1154 |
|
| 1155 | insn[0].imm = new_val;
|
| 1156 | insn[1].imm = new_val >> 32;
|
| 1157 | pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %llu\n",
|
| 1158 | prog_name, relo_idx, insn_idx,
|
| 1159 | (unsigned long long)imm, (unsigned long long)new_val);
|
| 1160 | break;
|
| 1161 | }
|
| 1162 | default:
|
| 1163 | bad_insn:
|
| 1164 | pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n",
|
| 1165 | prog_name, relo_idx, insn_idx, insn->code,
|
| 1166 | (unsigned)insn->src_reg, (unsigned)insn->dst_reg, (unsigned)insn->off, (unsigned)insn->imm);
|
| 1167 | return -EINVAL;
|
| 1168 | }
|
| 1169 |
|
| 1170 | return 0;
|
| 1171 | }
|
| 1172 |
|
| 1173 | |
| 1174 | * [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
|
| 1175 | * where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
|
| 1176 |
|
| 1177 | int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec)
|
| 1178 | {
|
| 1179 | const struct btf_type *t;
|
| 1180 | const char *s;
|
| 1181 | __u32 type_id;
|
| 1182 | int i, len = 0;
|
| 1183 |
|
| 1184 | #define append_buf(fmt, args...) \
|
| 1185 | ({ \
|
| 1186 | int r; \
|
| 1187 | r = snprintf(buf, buf_sz, fmt, ##args); \
|
| 1188 | len += r; \
|
| 1189 | if (r >= buf_sz) \
|
| 1190 | r = buf_sz; \
|
| 1191 | buf += r; \
|
| 1192 | buf_sz -= r; \
|
| 1193 | })
|
| 1194 |
|
| 1195 | type_id = spec->root_type_id;
|
| 1196 | t = btf_type_by_id(spec->btf, type_id);
|
| 1197 | s = btf__name_by_offset(spec->btf, t->name_off);
|
| 1198 |
|
| 1199 | append_buf("<%s> [%u] %s %s",
|
| 1200 | core_relo_kind_str(spec->relo_kind),
|
| 1201 | type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
|
| 1202 |
|
| 1203 | if (core_relo_is_type_based(spec->relo_kind))
|
| 1204 | return len;
|
| 1205 |
|
| 1206 | if (core_relo_is_enumval_based(spec->relo_kind)) {
|
| 1207 | t = skip_mods_and_typedefs(spec->btf, type_id, NULL);
|
| 1208 | if (btf_is_enum(t)) {
|
| 1209 | const struct btf_enum *e;
|
| 1210 | const char *fmt_str;
|
| 1211 |
|
| 1212 | e = btf_enum(t) + spec->raw_spec[0];
|
| 1213 | s = btf__name_by_offset(spec->btf, e->name_off);
|
| 1214 | fmt_str = BTF_INFO_KFLAG(t->info) ? "::%s = %d" : "::%s = %u";
|
| 1215 | append_buf(fmt_str, s, e->val);
|
| 1216 | } else {
|
| 1217 | const struct btf_enum64 *e;
|
| 1218 | const char *fmt_str;
|
| 1219 |
|
| 1220 | e = btf_enum64(t) + spec->raw_spec[0];
|
| 1221 | s = btf__name_by_offset(spec->btf, e->name_off);
|
| 1222 | fmt_str = BTF_INFO_KFLAG(t->info) ? "::%s = %lld" : "::%s = %llu";
|
| 1223 | append_buf(fmt_str, s, (unsigned long long)btf_enum64_value(e));
|
| 1224 | }
|
| 1225 | return len;
|
| 1226 | }
|
| 1227 |
|
| 1228 | if (core_relo_is_field_based(spec->relo_kind)) {
|
| 1229 | for (i = 0; i < spec->len; i++) {
|
| 1230 | if (spec->spec[i].name)
|
| 1231 | append_buf(".%s", spec->spec[i].name);
|
| 1232 | else if (i > 0 || spec->spec[i].idx > 0)
|
| 1233 | append_buf("[%u]", spec->spec[i].idx);
|
| 1234 | }
|
| 1235 |
|
| 1236 | append_buf(" (");
|
| 1237 | for (i = 0; i < spec->raw_len; i++)
|
| 1238 | append_buf("%s%d", i == 0 ? "" : ":", spec->raw_spec[i]);
|
| 1239 |
|
| 1240 | if (spec->bit_offset % 8)
|
| 1241 | append_buf(" @ offset %u.%u)", spec->bit_offset / 8, spec->bit_offset % 8);
|
| 1242 | else
|
| 1243 | append_buf(" @ offset %u)", spec->bit_offset / 8);
|
| 1244 | return len;
|
| 1245 | }
|
| 1246 |
|
| 1247 | return len;
|
| 1248 | #undef append_buf
|
| 1249 | }
|
| 1250 |
|
| 1251 | |
| 1252 | * Calculate CO-RE relocation target result.
|
| 1253 | *
|
| 1254 | * The outline and important points of the algorithm:
|
| 1255 | * 1. For given local type, find corresponding candidate target types.
|
| 1256 | * Candidate type is a type with the same "essential" name, ignoring
|
| 1257 | * everything after last triple underscore (___). E.g., `sample`,
|
| 1258 | * `sample___flavor_one`, `sample___flavor_another_one`, are all candidates
|
| 1259 | * for each other. Names with triple underscore are referred to as
|
| 1260 | * "flavors" and are useful, among other things, to allow to
|
| 1261 | * specify/support incompatible variations of the same kernel struct, which
|
| 1262 | * might differ between different kernel versions and/or build
|
| 1263 | * configurations.
|
| 1264 | *
|
| 1265 | * N.B. Struct "flavors" could be generated by bpftool's BTF-to-C
|
| 1266 | * converter, when deduplicated BTF of a kernel still contains more than
|
| 1267 | * one different types with the same name. In that case, ___2, ___3, etc
|
| 1268 | * are appended starting from second name conflict. But start flavors are
|
| 1269 | * also useful to be defined "locally", in BPF program, to extract same
|
| 1270 | * data from incompatible changes between different kernel
|
| 1271 | * versions/configurations. For instance, to handle field renames between
|
| 1272 | * kernel versions, one can use two flavors of the struct name with the
|
| 1273 | * same common name and use conditional relocations to extract that field,
|
| 1274 | * depending on target kernel version.
|
| 1275 | * 2. For each candidate type, try to match local specification to this
|
| 1276 | * candidate target type. Matching involves finding corresponding
|
| 1277 | * high-level spec accessors, meaning that all named fields should match,
|
| 1278 | * as well as all array accesses should be within the actual bounds. Also,
|
| 1279 | * types should be compatible (see bpf_core_fields_are_compat for details).
|
| 1280 | * 3. It is supported and expected that there might be multiple flavors
|
| 1281 | * matching the spec. As long as all the specs resolve to the same set of
|
| 1282 | * offsets across all candidates, there is no error. If there is any
|
| 1283 | * ambiguity, CO-RE relocation will fail. This is necessary to accommodate
|
| 1284 | * imperfection of BTF deduplication, which can cause slight duplication of
|
| 1285 | * the same BTF type, if some directly or indirectly referenced (by
|
| 1286 | * pointer) type gets resolved to different actual types in different
|
| 1287 | * object files. If such a situation occurs, deduplicated BTF will end up
|
| 1288 | * with two (or more) structurally identical types, which differ only in
|
| 1289 | * types they refer to through pointer. This should be OK in most cases and
|
| 1290 | * is not an error.
|
| 1291 | * 4. Candidate types search is performed by linearly scanning through all
|
| 1292 | * types in target BTF. It is anticipated that this is overall more
|
| 1293 | * efficient memory-wise and not significantly worse (if not better)
|
| 1294 | * CPU-wise compared to prebuilding a map from all local type names to
|
| 1295 | * a list of candidate type names. It's also sped up by caching resolved
|
| 1296 | * list of matching candidates per each local "root" type ID, that has at
|
| 1297 | * least one bpf_core_relo associated with it. This list is shared
|
| 1298 | * between multiple relocations for the same type ID and is updated as some
|
| 1299 | * of the candidates are pruned due to structural incompatibility.
|
| 1300 |
|
| 1301 | int bpf_core_calc_relo_insn(const char *prog_name,
|
| 1302 | const struct bpf_core_relo *relo,
|
| 1303 | int relo_idx,
|
| 1304 | const struct btf *local_btf,
|
| 1305 | struct bpf_core_cand_list *cands,
|
| 1306 | struct bpf_core_spec *specs_scratch,
|
| 1307 | struct bpf_core_relo_res *targ_res)
|
| 1308 | {
|
| 1309 | struct bpf_core_spec *local_spec = &specs_scratch[0];
|
| 1310 | struct bpf_core_spec *cand_spec = &specs_scratch[1];
|
| 1311 | struct bpf_core_spec *targ_spec = &specs_scratch[2];
|
| 1312 | struct bpf_core_relo_res cand_res;
|
| 1313 | const struct btf_type *local_type;
|
| 1314 | const char *local_name;
|
| 1315 | __u32 local_id;
|
| 1316 | char spec_buf[256];
|
| 1317 | int i, j, err;
|
| 1318 |
|
| 1319 | local_id = relo->type_id;
|
| 1320 | local_type = btf_type_by_id(local_btf, local_id);
|
| 1321 | local_name = btf__name_by_offset(local_btf, local_type->name_off);
|
| 1322 | if (!local_name)
|
| 1323 | return -EINVAL;
|
| 1324 |
|
| 1325 | err = bpf_core_parse_spec(prog_name, local_btf, relo, local_spec);
|
| 1326 | if (err) {
|
| 1327 | const char *spec_str;
|
| 1328 |
|
| 1329 | spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
|
| 1330 | pr_warn("prog '%s': relo #%d: parsing [%u] %s %s + %s failed: %d\n",
|
| 1331 | prog_name, relo_idx, local_id, btf_kind_str(local_type),
|
| 1332 | str_is_empty(local_name) ? "<anon>" : local_name,
|
| 1333 | spec_str ?: "<?>", err);
|
| 1334 | return -EINVAL;
|
| 1335 | }
|
| 1336 |
|
| 1337 | bpf_core_format_spec(spec_buf, sizeof(spec_buf), local_spec);
|
| 1338 | pr_debug("prog '%s': relo #%d: %s\n", prog_name, relo_idx, spec_buf);
|
| 1339 |
|
| 1340 |
|
| 1341 | if (relo->kind == BPF_CORE_TYPE_ID_LOCAL) {
|
| 1342 |
|
| 1343 | memset(targ_res, 0, sizeof(*targ_res));
|
| 1344 | targ_res->validate = false;
|
| 1345 | targ_res->poison = false;
|
| 1346 | targ_res->orig_val = local_spec->root_type_id;
|
| 1347 | targ_res->new_val = local_spec->root_type_id;
|
| 1348 | return 0;
|
| 1349 | }
|
| 1350 |
|
| 1351 |
|
| 1352 | if (str_is_empty(local_name)) {
|
| 1353 | pr_warn("prog '%s': relo #%d: <%s> (%u) relocation doesn't support anonymous types\n",
|
| 1354 | prog_name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
|
| 1355 | return -EOPNOTSUPP;
|
| 1356 | }
|
| 1357 |
|
| 1358 | for (i = 0, j = 0; i < cands->len; i++) {
|
| 1359 | err = bpf_core_spec_match(local_spec, cands->cands[i].btf,
|
| 1360 | cands->cands[i].id, cand_spec);
|
| 1361 | if (err < 0) {
|
| 1362 | bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
|
| 1363 | pr_warn("prog '%s': relo #%d: error matching candidate #%d %s: %d\n",
|
| 1364 | prog_name, relo_idx, i, spec_buf, err);
|
| 1365 | return err;
|
| 1366 | }
|
| 1367 |
|
| 1368 | bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
|
| 1369 | pr_debug("prog '%s': relo #%d: %s candidate #%d %s\n", prog_name,
|
| 1370 | relo_idx, err == 0 ? "non-matching" : "matching", i, spec_buf);
|
| 1371 |
|
| 1372 | if (err == 0)
|
| 1373 | continue;
|
| 1374 |
|
| 1375 | err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, cand_spec, &cand_res);
|
| 1376 | if (err)
|
| 1377 | return err;
|
| 1378 |
|
| 1379 | if (j == 0) {
|
| 1380 | *targ_res = cand_res;
|
| 1381 | *targ_spec = *cand_spec;
|
| 1382 | } else if (cand_spec->bit_offset != targ_spec->bit_offset) {
|
| 1383 | |
| 1384 | * should all resolve to the same bit offset
|
| 1385 |
|
| 1386 | pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
|
| 1387 | prog_name, relo_idx, cand_spec->bit_offset,
|
| 1388 | targ_spec->bit_offset);
|
| 1389 | return -EINVAL;
|
| 1390 | } else if (cand_res.poison != targ_res->poison ||
|
| 1391 | cand_res.new_val != targ_res->new_val) {
|
| 1392 | |
| 1393 | * decision and value, otherwise it's dangerous to
|
| 1394 | * proceed due to ambiguity
|
| 1395 |
|
| 1396 | pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %llu != %s %llu\n",
|
| 1397 | prog_name, relo_idx,
|
| 1398 | cand_res.poison ? "failure" : "success",
|
| 1399 | (unsigned long long)cand_res.new_val,
|
| 1400 | targ_res->poison ? "failure" : "success",
|
| 1401 | (unsigned long long)targ_res->new_val);
|
| 1402 | return -EINVAL;
|
| 1403 | }
|
| 1404 |
|
| 1405 | cands->cands[j++] = cands->cands[i];
|
| 1406 | }
|
| 1407 |
|
| 1408 | |
| 1409 | * For BPF_CORE_FIELD_EXISTS relo or when used BPF program has field
|
| 1410 | * existence checks or kernel version/config checks, it's expected
|
| 1411 | * that we might not find any candidates. In this case, if field
|
| 1412 | * wasn't found in any candidate, the list of candidates shouldn't
|
| 1413 | * change at all, we'll just handle relocating appropriately,
|
| 1414 | * depending on relo's kind.
|
| 1415 |
|
| 1416 | if (j > 0)
|
| 1417 | cands->len = j;
|
| 1418 |
|
| 1419 | |
| 1420 | * If no candidates were found, it might be both a programmer error,
|
| 1421 | * as well as expected case, depending whether instruction w/
|
| 1422 | * relocation is guarded in some way that makes it unreachable (dead
|
| 1423 | * code) if relocation can't be resolved. This is handled in
|
| 1424 | * bpf_core_patch_insn() uniformly by replacing that instruction with
|
| 1425 | * BPF helper call insn (using invalid helper ID). If that instruction
|
| 1426 | * is indeed unreachable, then it will be ignored and eliminated by
|
| 1427 | * verifier. If it was an error, then verifier will complain and point
|
| 1428 | * to a specific instruction number in its log.
|
| 1429 |
|
| 1430 | if (j == 0) {
|
| 1431 | pr_debug("prog '%s': relo #%d: no matching targets found\n",
|
| 1432 | prog_name, relo_idx);
|
| 1433 |
|
| 1434 |
|
| 1435 | err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, NULL, targ_res);
|
| 1436 | if (err)
|
| 1437 | return err;
|
| 1438 | }
|
| 1439 |
|
| 1440 | return 0;
|
| 1441 | }
|
| 1442 |
|
| 1443 | static bool bpf_core_names_match(const struct btf *local_btf, size_t local_name_off,
|
| 1444 | const struct btf *targ_btf, size_t targ_name_off)
|
| 1445 | {
|
| 1446 | const char *local_n, *targ_n;
|
| 1447 | size_t local_len, targ_len;
|
| 1448 |
|
| 1449 | local_n = btf__name_by_offset(local_btf, local_name_off);
|
| 1450 | targ_n = btf__name_by_offset(targ_btf, targ_name_off);
|
| 1451 |
|
| 1452 | if (str_is_empty(targ_n))
|
| 1453 | return str_is_empty(local_n);
|
| 1454 |
|
| 1455 | targ_len = bpf_core_essential_name_len(targ_n);
|
| 1456 | local_len = bpf_core_essential_name_len(local_n);
|
| 1457 |
|
| 1458 | return targ_len == local_len && strncmp(local_n, targ_n, local_len) == 0;
|
| 1459 | }
|
| 1460 |
|
| 1461 | static int bpf_core_enums_match(const struct btf *local_btf, const struct btf_type *local_t,
|
| 1462 | const struct btf *targ_btf, const struct btf_type *targ_t)
|
| 1463 | {
|
| 1464 | __u32 local_vlen = btf_vlen(local_t);
|
| 1465 | __u32 targ_vlen = btf_vlen(targ_t);
|
| 1466 | int i, j;
|
| 1467 |
|
| 1468 | if (local_t->size != targ_t->size)
|
| 1469 | return 0;
|
| 1470 |
|
| 1471 | if (local_vlen > targ_vlen)
|
| 1472 | return 0;
|
| 1473 |
|
| 1474 | |
| 1475 | * a symbolic name correspondent in the target
|
| 1476 |
|
| 1477 | for (i = 0; i < local_vlen; i++) {
|
| 1478 | bool matched = false;
|
| 1479 | __u32 local_n_off, targ_n_off;
|
| 1480 |
|
| 1481 | local_n_off = btf_is_enum(local_t) ? btf_enum(local_t)[i].name_off :
|
| 1482 | btf_enum64(local_t)[i].name_off;
|
| 1483 |
|
| 1484 | for (j = 0; j < targ_vlen; j++) {
|
| 1485 | targ_n_off = btf_is_enum(targ_t) ? btf_enum(targ_t)[j].name_off :
|
| 1486 | btf_enum64(targ_t)[j].name_off;
|
| 1487 |
|
| 1488 | if (bpf_core_names_match(local_btf, local_n_off, targ_btf, targ_n_off)) {
|
| 1489 | matched = true;
|
| 1490 | break;
|
| 1491 | }
|
| 1492 | }
|
| 1493 |
|
| 1494 | if (!matched)
|
| 1495 | return 0;
|
| 1496 | }
|
| 1497 | return 1;
|
| 1498 | }
|
| 1499 |
|
| 1500 | static int bpf_core_composites_match(const struct btf *local_btf, const struct btf_type *local_t,
|
| 1501 | const struct btf *targ_btf, const struct btf_type *targ_t,
|
| 1502 | bool behind_ptr, int level)
|
| 1503 | {
|
| 1504 | const struct btf_member *local_m = btf_members(local_t);
|
| 1505 | __u32 local_vlen = btf_vlen(local_t);
|
| 1506 | __u32 targ_vlen = btf_vlen(targ_t);
|
| 1507 | int i, j, err;
|
| 1508 |
|
| 1509 | if (local_vlen > targ_vlen)
|
| 1510 | return 0;
|
| 1511 |
|
| 1512 |
|
| 1513 | for (i = 0; i < local_vlen; i++, local_m++) {
|
| 1514 | const struct btf_member *targ_m = btf_members(targ_t);
|
| 1515 | bool matched = false;
|
| 1516 |
|
| 1517 | for (j = 0; j < targ_vlen; j++, targ_m++) {
|
| 1518 | if (!bpf_core_names_match(local_btf, local_m->name_off,
|
| 1519 | targ_btf, targ_m->name_off))
|
| 1520 | continue;
|
| 1521 |
|
| 1522 | err = __bpf_core_types_match(local_btf, local_m->type, targ_btf,
|
| 1523 | targ_m->type, behind_ptr, level - 1);
|
| 1524 | if (err < 0)
|
| 1525 | return err;
|
| 1526 | if (err > 0) {
|
| 1527 | matched = true;
|
| 1528 | break;
|
| 1529 | }
|
| 1530 | }
|
| 1531 |
|
| 1532 | if (!matched)
|
| 1533 | return 0;
|
| 1534 | }
|
| 1535 | return 1;
|
| 1536 | }
|
| 1537 |
|
| 1538 | |
| 1539 | * already checked for name match.
|
| 1540 | *
|
| 1541 | * The matching relation is defined as follows:
|
| 1542 | * - modifiers and typedefs are stripped (and, hence, effectively ignored)
|
| 1543 | * - generally speaking types need to be of same kind (struct vs. struct, union
|
| 1544 | * vs. union, etc.)
|
| 1545 | * - exceptions are struct/union behind a pointer which could also match a
|
| 1546 | * forward declaration of a struct or union, respectively, and enum vs.
|
| 1547 | * enum64 (see below)
|
| 1548 | * Then, depending on type:
|
| 1549 | * - integers:
|
| 1550 | * - match if size and signedness match
|
| 1551 | * - arrays & pointers:
|
| 1552 | * - target types are recursively matched
|
| 1553 | * - structs & unions:
|
| 1554 | * - local members need to exist in target with the same name
|
| 1555 | * - for each member we recursively check match unless it is already behind a
|
| 1556 | * pointer, in which case we only check matching names and compatible kind
|
| 1557 | * - enums:
|
| 1558 | * - local variants have to have a match in target by symbolic name (but not
|
| 1559 | * numeric value)
|
| 1560 | * - size has to match (but enum may match enum64 and vice versa)
|
| 1561 | * - function pointers:
|
| 1562 | * - number and position of arguments in local type has to match target
|
| 1563 | * - for each argument and the return value we recursively check match
|
| 1564 |
|
| 1565 | int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
|
| 1566 | __u32 targ_id, bool behind_ptr, int level)
|
| 1567 | {
|
| 1568 | const struct btf_type *local_t, *targ_t;
|
| 1569 | int depth = 32;
|
| 1570 | __u16 local_k, targ_k;
|
| 1571 |
|
| 1572 | if (level <= 0)
|
| 1573 | return -EINVAL;
|
| 1574 |
|
| 1575 | recur:
|
| 1576 | depth--;
|
| 1577 | if (depth < 0)
|
| 1578 | return -EINVAL;
|
| 1579 |
|
| 1580 | local_t = skip_mods_and_typedefs(local_btf, local_id, &local_id);
|
| 1581 | targ_t = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
| 1582 | if (!local_t || !targ_t)
|
| 1583 | return -EINVAL;
|
| 1584 |
|
| 1585 | |
| 1586 | * typedefs would still be name-matched as that's the contract with
|
| 1587 | * callers.
|
| 1588 |
|
| 1589 | if (!bpf_core_names_match(local_btf, local_t->name_off, targ_btf, targ_t->name_off))
|
| 1590 | return 0;
|
| 1591 |
|
| 1592 | local_k = btf_kind(local_t);
|
| 1593 | targ_k = btf_kind(targ_t);
|
| 1594 |
|
| 1595 | switch (local_k) {
|
| 1596 | case BTF_KIND_UNKN:
|
| 1597 | return local_k == targ_k;
|
| 1598 | case BTF_KIND_FWD: {
|
| 1599 | bool local_f = BTF_INFO_KFLAG(local_t->info);
|
| 1600 |
|
| 1601 | if (behind_ptr) {
|
| 1602 | if (local_k == targ_k)
|
| 1603 | return local_f == BTF_INFO_KFLAG(targ_t->info);
|
| 1604 |
|
| 1605 | |
| 1606 | * target is a struct (0) or union (1)
|
| 1607 |
|
| 1608 | return (targ_k == BTF_KIND_STRUCT && !local_f) ||
|
| 1609 | (targ_k == BTF_KIND_UNION && local_f);
|
| 1610 | } else {
|
| 1611 | if (local_k != targ_k)
|
| 1612 | return 0;
|
| 1613 |
|
| 1614 |
|
| 1615 | return local_f == BTF_INFO_KFLAG(targ_t->info);
|
| 1616 | }
|
| 1617 | }
|
| 1618 | case BTF_KIND_ENUM:
|
| 1619 | case BTF_KIND_ENUM64:
|
| 1620 | if (!btf_is_any_enum(targ_t))
|
| 1621 | return 0;
|
| 1622 |
|
| 1623 | return bpf_core_enums_match(local_btf, local_t, targ_btf, targ_t);
|
| 1624 | case BTF_KIND_STRUCT:
|
| 1625 | case BTF_KIND_UNION:
|
| 1626 | if (behind_ptr) {
|
| 1627 | bool targ_f = BTF_INFO_KFLAG(targ_t->info);
|
| 1628 |
|
| 1629 | if (local_k == targ_k)
|
| 1630 | return 1;
|
| 1631 |
|
| 1632 | if (targ_k != BTF_KIND_FWD)
|
| 1633 | return 0;
|
| 1634 |
|
| 1635 | return (local_k == BTF_KIND_UNION) == targ_f;
|
| 1636 | } else {
|
| 1637 | if (local_k != targ_k)
|
| 1638 | return 0;
|
| 1639 |
|
| 1640 | return bpf_core_composites_match(local_btf, local_t, targ_btf, targ_t,
|
| 1641 | behind_ptr, level);
|
| 1642 | }
|
| 1643 | case BTF_KIND_INT: {
|
| 1644 | __u8 local_sgn;
|
| 1645 | __u8 targ_sgn;
|
| 1646 |
|
| 1647 | if (local_k != targ_k)
|
| 1648 | return 0;
|
| 1649 |
|
| 1650 | local_sgn = btf_int_encoding(local_t) & BTF_INT_SIGNED;
|
| 1651 | targ_sgn = btf_int_encoding(targ_t) & BTF_INT_SIGNED;
|
| 1652 |
|
| 1653 | return local_t->size == targ_t->size && local_sgn == targ_sgn;
|
| 1654 | }
|
| 1655 | case BTF_KIND_PTR:
|
| 1656 | if (local_k != targ_k)
|
| 1657 | return 0;
|
| 1658 |
|
| 1659 | behind_ptr = true;
|
| 1660 |
|
| 1661 | local_id = local_t->type;
|
| 1662 | targ_id = targ_t->type;
|
| 1663 | goto recur;
|
| 1664 | case BTF_KIND_ARRAY: {
|
| 1665 | const struct btf_array *local_array = btf_array(local_t);
|
| 1666 | const struct btf_array *targ_array = btf_array(targ_t);
|
| 1667 |
|
| 1668 | if (local_k != targ_k)
|
| 1669 | return 0;
|
| 1670 |
|
| 1671 | if (local_array->nelems != targ_array->nelems)
|
| 1672 | return 0;
|
| 1673 |
|
| 1674 | local_id = local_array->type;
|
| 1675 | targ_id = targ_array->type;
|
| 1676 | goto recur;
|
| 1677 | }
|
| 1678 | case BTF_KIND_FUNC_PROTO: {
|
| 1679 | struct btf_param *local_p = btf_params(local_t);
|
| 1680 | struct btf_param *targ_p = btf_params(targ_t);
|
| 1681 | __u32 local_vlen = btf_vlen(local_t);
|
| 1682 | __u32 targ_vlen = btf_vlen(targ_t);
|
| 1683 | int i, err;
|
| 1684 |
|
| 1685 | if (local_k != targ_k)
|
| 1686 | return 0;
|
| 1687 |
|
| 1688 | if (local_vlen != targ_vlen)
|
| 1689 | return 0;
|
| 1690 |
|
| 1691 | for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
|
| 1692 | err = __bpf_core_types_match(local_btf, local_p->type, targ_btf,
|
| 1693 | targ_p->type, behind_ptr, level - 1);
|
| 1694 | if (err <= 0)
|
| 1695 | return err;
|
| 1696 | }
|
| 1697 |
|
| 1698 |
|
| 1699 | local_id = local_t->type;
|
| 1700 | targ_id = targ_t->type;
|
| 1701 | goto recur;
|
| 1702 | }
|
| 1703 | default:
|
| 1704 | pr_warn("unexpected kind %s relocated, local [%u], target [%u]\n",
|
| 1705 | btf_kind_str(local_t), local_id, targ_id);
|
| 1706 | return 0;
|
| 1707 | }
|
| 1708 | }
|