1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 3 */ 4#ifndef _LINUX_BPF_VERIFIER_H 5#define _LINUX_BPF_VERIFIER_H 1 6 7#include <linux/bpf.h> /* for enum bpf_reg_type */ 8#include <linux/btf.h> /* for struct btf and btf_id() */ 9#include <linux/filter.h> /* for MAX_BPF_STACK */ 10#include <linux/tnum.h> 11 12/* Maximum variable offset umax_value permitted when resolving memory accesses. 13 * In practice this is far bigger than any realistic pointer offset; this limit 14 * ensures that umax_value + (int)off + (int)size cannot overflow a u64. 15 */ 16#define BPF_MAX_VAR_OFF (1 << 29) 17/* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures 18 * that converting umax_value to int cannot overflow. 19 */ 20#define BPF_MAX_VAR_SIZ (1 << 29) 21/* size of tmp_str_buf in bpf_verifier. 22 * we need at least 306 bytes to fit full stack mask representation 23 * (in the "-8,-16,...,-512" form) 24 */ 25#define TMP_STR_BUF_LEN 320 26 27/* Liveness marks, used for registers and spilled-regs (in stack slots). 28 * Read marks propagate upwards until they find a write mark; they record that 29 * "one of this state's descendants read this reg" (and therefore the reg is 30 * relevant for states_equal() checks). 31 * Write marks collect downwards and do not propagate; they record that "the 32 * straight-line code that reached this state (from its parent) wrote this reg" 33 * (and therefore that reads propagated from this state or its descendants 34 * should not propagate to its parent). 35 * A state with a write mark can receive read marks; it just won't propagate 36 * them to its parent, since the write mark is a property, not of the state, 37 * but of the link between it and its parent. See mark_reg_read() and 38 * mark_stack_slot_read() in kernel/bpf/verifier.c. 39 */ 40enum bpf_reg_liveness { 41 REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */ 42 REG_LIVE_READ32 = 0x1, /* reg was read, so we're sensitive to initial value */ 43 REG_LIVE_READ64 = 0x2, /* likewise, but full 64-bit content matters */ 44 REG_LIVE_READ = REG_LIVE_READ32 | REG_LIVE_READ64, 45 REG_LIVE_WRITTEN = 0x4, /* reg was written first, screening off later reads */ 46 REG_LIVE_DONE = 0x8, /* liveness won't be updating this register anymore */ 47}; 48 49/* For every reg representing a map value or allocated object pointer, 50 * we consider the tuple of (ptr, id) for them to be unique in verifier 51 * context and conside them to not alias each other for the purposes of 52 * tracking lock state. 53 */ 54struct bpf_active_lock { 55 /* This can either be reg->map_ptr or reg->btf. If ptr is NULL, 56 * there's no active lock held, and other fields have no 57 * meaning. If non-NULL, it indicates that a lock is held and 58 * id member has the reg->id of the register which can be >= 0. 59 */ 60 void *ptr; 61 /* This will be reg->id */ 62 u32 id; 63}; 64 65#define ITER_PREFIX "bpf_iter_" 66 67enum bpf_iter_state { 68 BPF_ITER_STATE_INVALID, /* for non-first slot */ 69 BPF_ITER_STATE_ACTIVE, 70 BPF_ITER_STATE_DRAINED, 71}; 72 73struct bpf_reg_state { 74 /* Ordering of fields matters. See states_equal() */ 75 enum bpf_reg_type type; 76 /* Fixed part of pointer offset, pointer types only */ 77 s32 off; 78 union { 79 /* valid when type == PTR_TO_PACKET */ 80 int range; 81 82 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | 83 * PTR_TO_MAP_VALUE_OR_NULL 84 */ 85 struct { 86 struct bpf_map *map_ptr; 87 /* To distinguish map lookups from outer map 88 * the map_uid is non-zero for registers 89 * pointing to inner maps. 90 */ 91 u32 map_uid; 92 }; 93 94 /* for PTR_TO_BTF_ID */ 95 struct { 96 struct btf *btf; 97 u32 btf_id; 98 }; 99 100 struct { /* for PTR_TO_MEM | PTR_TO_MEM_OR_NULL */ 101 u32 mem_size; 102 u32 dynptr_id; /* for dynptr slices */ 103 }; 104 105 /* For dynptr stack slots */ 106 struct { 107 enum bpf_dynptr_type type; 108 /* A dynptr is 16 bytes so it takes up 2 stack slots. 109 * We need to track which slot is the first slot 110 * to protect against cases where the user may try to 111 * pass in an address starting at the second slot of the 112 * dynptr. 113 */ 114 bool first_slot; 115 } dynptr; 116 117 /* For bpf_iter stack slots */ 118 struct { 119 /* BTF container and BTF type ID describing 120 * struct bpf_iter_<type> of an iterator state 121 */ 122 struct btf *btf; 123 u32 btf_id; 124 /* packing following two fields to fit iter state into 16 bytes */ 125 enum bpf_iter_state state:2; 126 int depth:30; 127 } iter; 128 129 /* Max size from any of the above. */ 130 struct { 131 unsigned long raw1; 132 unsigned long raw2; 133 } raw; 134 135 u32 subprogno; /* for PTR_TO_FUNC */ 136 }; 137 /* For scalar types (SCALAR_VALUE), this represents our knowledge of 138 * the actual value. 139 * For pointer types, this represents the variable part of the offset 140 * from the pointed-to object, and is shared with all bpf_reg_states 141 * with the same id as us. 142 */ 143 struct tnum var_off; 144 /* Used to determine if any memory access using this register will 145 * result in a bad access. 146 * These refer to the same value as var_off, not necessarily the actual 147 * contents of the register. 148 */ 149 s64 smin_value; /* minimum possible (s64)value */ 150 s64 smax_value; /* maximum possible (s64)value */ 151 u64 umin_value; /* minimum possible (u64)value */ 152 u64 umax_value; /* maximum possible (u64)value */ 153 s32 s32_min_value; /* minimum possible (s32)value */ 154 s32 s32_max_value; /* maximum possible (s32)value */ 155 u32 u32_min_value; /* minimum possible (u32)value */ 156 u32 u32_max_value; /* maximum possible (u32)value */ 157 /* For PTR_TO_PACKET, used to find other pointers with the same variable 158 * offset, so they can share range knowledge. 159 * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we 160 * came from, when one is tested for != NULL. 161 * For PTR_TO_MEM_OR_NULL this is used to identify memory allocation 162 * for the purpose of tracking that it's freed. 163 * For PTR_TO_SOCKET this is used to share which pointers retain the 164 * same reference to the socket, to determine proper reference freeing. 165 * For stack slots that are dynptrs, this is used to track references to 166 * the dynptr to determine proper reference freeing. 167 * Similarly to dynptrs, we use ID to track "belonging" of a reference 168 * to a specific instance of bpf_iter. 169 */ 170 u32 id; 171 /* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned 172 * from a pointer-cast helper, bpf_sk_fullsock() and 173 * bpf_tcp_sock(). 174 * 175 * Consider the following where "sk" is a reference counted 176 * pointer returned from "sk = bpf_sk_lookup_tcp();": 177 * 178 * 1: sk = bpf_sk_lookup_tcp(); 179 * 2: if (!sk) { return 0; } 180 * 3: fullsock = bpf_sk_fullsock(sk); 181 * 4: if (!fullsock) { bpf_sk_release(sk); return 0; } 182 * 5: tp = bpf_tcp_sock(fullsock); 183 * 6: if (!tp) { bpf_sk_release(sk); return 0; } 184 * 7: bpf_sk_release(sk); 185 * 8: snd_cwnd = tp->snd_cwnd; // verifier will complain 186 * 187 * After bpf_sk_release(sk) at line 7, both "fullsock" ptr and 188 * "tp" ptr should be invalidated also. In order to do that, 189 * the reg holding "fullsock" and "sk" need to remember 190 * the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id 191 * such that the verifier can reset all regs which have 192 * ref_obj_id matching the sk_reg->id. 193 * 194 * sk_reg->ref_obj_id is set to sk_reg->id at line 1. 195 * sk_reg->id will stay as NULL-marking purpose only. 196 * After NULL-marking is done, sk_reg->id can be reset to 0. 197 * 198 * After "fullsock = bpf_sk_fullsock(sk);" at line 3, 199 * fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id. 200 * 201 * After "tp = bpf_tcp_sock(fullsock);" at line 5, 202 * tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id 203 * which is the same as sk_reg->ref_obj_id. 204 * 205 * From the verifier perspective, if sk, fullsock and tp 206 * are not NULL, they are the same ptr with different 207 * reg->type. In particular, bpf_sk_release(tp) is also 208 * allowed and has the same effect as bpf_sk_release(sk). 209 */ 210 u32 ref_obj_id; 211 /* parentage chain for liveness checking */ 212 struct bpf_reg_state *parent; 213 /* Inside the callee two registers can be both PTR_TO_STACK like 214 * R1=fp-8 and R2=fp-8, but one of them points to this function stack 215 * while another to the caller's stack. To differentiate them 'frameno' 216 * is used which is an index in bpf_verifier_state->frame[] array 217 * pointing to bpf_func_state. 218 */ 219 u32 frameno; 220 /* Tracks subreg definition. The stored value is the insn_idx of the 221 * writing insn. This is safe because subreg_def is used before any insn 222 * patching which only happens after main verification finished. 223 */ 224 s32 subreg_def; 225 enum bpf_reg_liveness live; 226 /* if (!precise && SCALAR_VALUE) min/max/tnum don't affect safety */ 227 bool precise; 228}; 229 230enum bpf_stack_slot_type { 231 STACK_INVALID, /* nothing was stored in this stack slot */ 232 STACK_SPILL, /* register spilled into stack */ 233 STACK_MISC, /* BPF program wrote some data into this slot */ 234 STACK_ZERO, /* BPF program wrote constant zero */ 235 /* A dynptr is stored in this stack slot. The type of dynptr 236 * is stored in bpf_stack_state->spilled_ptr.dynptr.type 237 */ 238 STACK_DYNPTR, 239 STACK_ITER, 240}; 241 242#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ 243 244#define BPF_REGMASK_ARGS ((1 << BPF_REG_1) | (1 << BPF_REG_2) | \ 245 (1 << BPF_REG_3) | (1 << BPF_REG_4) | \ 246 (1 << BPF_REG_5)) 247 248#define BPF_DYNPTR_SIZE sizeof(struct bpf_dynptr_kern) 249#define BPF_DYNPTR_NR_SLOTS (BPF_DYNPTR_SIZE / BPF_REG_SIZE) 250 251struct bpf_stack_state { 252 struct bpf_reg_state spilled_ptr; 253 u8 slot_type[BPF_REG_SIZE]; 254}; 255 256struct bpf_reference_state { 257 /* Track each reference created with a unique id, even if the same 258 * instruction creates the reference multiple times (eg, via CALL). 259 */ 260 int id; 261 /* Instruction where the allocation of this reference occurred. This 262 * is used purely to inform the user of a reference leak. 263 */ 264 int insn_idx; 265 /* There can be a case like: 266 * main (frame 0) 267 * cb (frame 1) 268 * func (frame 3) 269 * cb (frame 4) 270 * Hence for frame 4, if callback_ref just stored boolean, it would be 271 * impossible to distinguish nested callback refs. Hence store the 272 * frameno and compare that to callback_ref in check_reference_leak when 273 * exiting a callback function. 274 */ 275 int callback_ref; 276}; 277 278struct bpf_retval_range { 279 s32 minval; 280 s32 maxval; 281}; 282 283/* state of the program: 284 * type of all registers and stack info 285 */ 286struct bpf_func_state { 287 struct bpf_reg_state regs[MAX_BPF_REG]; 288 /* index of call instruction that called into this func */ 289 int callsite; 290 /* stack frame number of this function state from pov of 291 * enclosing bpf_verifier_state. 292 * 0 = main function, 1 = first callee. 293 */ 294 u32 frameno; 295 /* subprog number == index within subprog_info 296 * zero == main subprog 297 */ 298 u32 subprogno; 299 /* Every bpf_timer_start will increment async_entry_cnt. 300 * It's used to distinguish: 301 * void foo(void) { for(;;); } 302 * void foo(void) { bpf_timer_set_callback(,foo); } 303 */ 304 u32 async_entry_cnt; 305 struct bpf_retval_range callback_ret_range; 306 bool in_callback_fn; 307 bool in_async_callback_fn; 308 bool in_exception_callback_fn; 309 /* For callback calling functions that limit number of possible 310 * callback executions (e.g. bpf_loop) keeps track of current 311 * simulated iteration number. 312 * Value in frame N refers to number of times callback with frame 313 * N+1 was simulated, e.g. for the following call: 314 * 315 * bpf_loop(..., fn, ...); | suppose current frame is N 316 * | fn would be simulated in frame N+1 317 * | number of simulations is tracked in frame N 318 */ 319 u32 callback_depth; 320 321 /* The following fields should be last. See copy_func_state() */ 322 int acquired_refs; 323 struct bpf_reference_state *refs; 324 /* The state of the stack. Each element of the array describes BPF_REG_SIZE 325 * (i.e. 8) bytes worth of stack memory. 326 * stack[0] represents bytes [*(r10-8)..*(r10-1)] 327 * stack[1] represents bytes [*(r10-16)..*(r10-9)] 328 * ... 329 * stack[allocated_stack/8 - 1] represents [*(r10-allocated_stack)..*(r10-allocated_stack+7)] 330 */ 331 struct bpf_stack_state *stack; 332 /* Size of the current stack, in bytes. The stack state is tracked below, in 333 * `stack`. allocated_stack is always a multiple of BPF_REG_SIZE. 334 */ 335 int allocated_stack; 336}; 337 338#define MAX_CALL_FRAMES 8 339 340/* instruction history flags, used in bpf_jmp_history_entry.flags field */ 341enum { 342 /* instruction references stack slot through PTR_TO_STACK register; 343 * we also store stack's frame number in lower 3 bits (MAX_CALL_FRAMES is 8) 344 * and accessed stack slot's index in next 6 bits (MAX_BPF_STACK is 512, 345 * 8 bytes per slot, so slot index (spi) is [0, 63]) 346 */ 347 INSN_F_FRAMENO_MASK = 0x7, /* 3 bits */ 348 349 INSN_F_SPI_MASK = 0x3f, /* 6 bits */ 350 INSN_F_SPI_SHIFT = 3, /* shifted 3 bits to the left */ 351 352 INSN_F_STACK_ACCESS = BIT(9), /* we need 10 bits total */ 353}; 354 355static_assert(INSN_F_FRAMENO_MASK + 1 >= MAX_CALL_FRAMES); 356static_assert(INSN_F_SPI_MASK + 1 >= MAX_BPF_STACK / 8); 357 358struct bpf_jmp_history_entry { 359 u32 idx; 360 /* insn idx can't be bigger than 1 million */ 361 u32 prev_idx : 22; 362 /* special flags, e.g., whether insn is doing register stack spill/load */ 363 u32 flags : 10; 364}; 365 366/* Maximum number of register states that can exist at once */ 367#define BPF_ID_MAP_SIZE ((MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) * MAX_CALL_FRAMES) 368struct bpf_verifier_state { 369 /* call stack tracking */ 370 struct bpf_func_state *frame[MAX_CALL_FRAMES]; 371 struct bpf_verifier_state *parent; 372 /* 373 * 'branches' field is the number of branches left to explore: 374 * 0 - all possible paths from this state reached bpf_exit or 375 * were safely pruned 376 * 1 - at least one path is being explored. 377 * This state hasn't reached bpf_exit 378 * 2 - at least two paths are being explored. 379 * This state is an immediate parent of two children. 380 * One is fallthrough branch with branches==1 and another 381 * state is pushed into stack (to be explored later) also with 382 * branches==1. The parent of this state has branches==1. 383 * The verifier state tree connected via 'parent' pointer looks like: 384 * 1 385 * 1 386 * 2 -> 1 (first 'if' pushed into stack) 387 * 1 388 * 2 -> 1 (second 'if' pushed into stack) 389 * 1 390 * 1 391 * 1 bpf_exit. 392 * 393 * Once do_check() reaches bpf_exit, it calls update_branch_counts() 394 * and the verifier state tree will look: 395 * 1 396 * 1 397 * 2 -> 1 (first 'if' pushed into stack) 398 * 1 399 * 1 -> 1 (second 'if' pushed into stack) 400 * 0 401 * 0 402 * 0 bpf_exit. 403 * After pop_stack() the do_check() will resume at second 'if'. 404 * 405 * If is_state_visited() sees a state with branches > 0 it means 406 * there is a loop. If such state is exactly equal to the current state 407 * it's an infinite loop. Note states_equal() checks for states 408 * equivalency, so two states being 'states_equal' does not mean 409 * infinite loop. The exact comparison is provided by 410 * states_maybe_looping() function. It's a stronger pre-check and 411 * much faster than states_equal(). 412 * 413 * This algorithm may not find all possible infinite loops or 414 * loop iteration count may be too high. 415 * In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in. 416 */ 417 u32 branches; 418 u32 insn_idx; 419 u32 curframe; 420 421 struct bpf_active_lock active_lock; 422 bool speculative; 423 bool active_rcu_lock; 424 /* If this state was ever pointed-to by other state's loop_entry field 425 * this flag would be set to true. Used to avoid freeing such states 426 * while they are still in use. 427 */ 428 bool used_as_loop_entry; 429 430 /* first and last insn idx of this verifier state */ 431 u32 first_insn_idx; 432 u32 last_insn_idx; 433 /* If this state is a part of states loop this field points to some 434 * parent of this state such that: 435 * - it is also a member of the same states loop; 436 * - DFS states traversal starting from initial state visits loop_entry 437 * state before this state. 438 * Used to compute topmost loop entry for state loops. 439 * State loops might appear because of open coded iterators logic. 440 * See get_loop_entry() for more information. 441 */ 442 struct bpf_verifier_state *loop_entry; 443 /* jmp history recorded from first to last. 444 * backtracking is using it to go from last to first. 445 * For most states jmp_history_cnt is [0-3]. 446 * For loops can go up to ~40. 447 */ 448 struct bpf_jmp_history_entry *jmp_history; 449 u32 jmp_history_cnt; 450 u32 dfs_depth; 451 u32 callback_unroll_depth; 452 u32 may_goto_depth; 453}; 454 455#define bpf_get_spilled_reg(slot, frame, mask) \ 456 (((slot < frame->allocated_stack / BPF_REG_SIZE) && \ 457 ((1 << frame->stack[slot].slot_type[BPF_REG_SIZE - 1]) & (mask))) \ 458 ? &frame->stack[slot].spilled_ptr : NULL) 459 460/* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */ 461#define bpf_for_each_spilled_reg(iter, frame, reg, mask) \ 462 for (iter = 0, reg = bpf_get_spilled_reg(iter, frame, mask); \ 463 iter < frame->allocated_stack / BPF_REG_SIZE; \ 464 iter++, reg = bpf_get_spilled_reg(iter, frame, mask)) 465 466#define bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, __mask, __expr) \ 467 ({ \ 468 struct bpf_verifier_state *___vstate = __vst; \ 469 int ___i, ___j; \ 470 for (___i = 0; ___i <= ___vstate->curframe; ___i++) { \ 471 struct bpf_reg_state *___regs; \ 472 __state = ___vstate->frame[___i]; \ 473 ___regs = __state->regs; \ 474 for (___j = 0; ___j < MAX_BPF_REG; ___j++) { \ 475 __reg = &___regs[___j]; \ 476 (void)(__expr); \ 477 } \ 478 bpf_for_each_spilled_reg(___j, __state, __reg, __mask) { \ 479 if (!__reg) \ 480 continue; \ 481 (void)(__expr); \ 482 } \ 483 } \ 484 }) 485 486/* Invoke __expr over regsiters in __vst, setting __state and __reg */ 487#define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr) \ 488 bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, 1 << STACK_SPILL, __expr) 489 490/* linked list of verifier states used to prune search */ 491struct bpf_verifier_state_list { 492 struct bpf_verifier_state state; 493 struct bpf_verifier_state_list *next; 494 int miss_cnt, hit_cnt; 495}; 496 497struct bpf_loop_inline_state { 498 unsigned int initialized:1; /* set to true upon first entry */ 499 unsigned int fit_for_inline:1; /* true if callback function is the same 500 * at each call and flags are always zero 501 */ 502 u32 callback_subprogno; /* valid when fit_for_inline is true */ 503}; 504 505/* Possible states for alu_state member. */ 506#define BPF_ALU_SANITIZE_SRC (1U << 0) 507#define BPF_ALU_SANITIZE_DST (1U << 1) 508#define BPF_ALU_NEG_VALUE (1U << 2) 509#define BPF_ALU_NON_POINTER (1U << 3) 510#define BPF_ALU_IMMEDIATE (1U << 4) 511#define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ 512 BPF_ALU_SANITIZE_DST) 513 514struct bpf_insn_aux_data { 515 union { 516 enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ 517 unsigned long map_ptr_state; /* pointer/poison value for maps */ 518 s32 call_imm; /* saved imm field of call insn */ 519 u32 alu_limit; /* limit for add/sub register with pointer */ 520 struct { 521 u32 map_index; /* index into used_maps[] */ 522 u32 map_off; /* offset from value base address */ 523 }; 524 struct { 525 enum bpf_reg_type reg_type; /* type of pseudo_btf_id */ 526 union { 527 struct { 528 struct btf *btf; 529 u32 btf_id; /* btf_id for struct typed var */ 530 }; 531 u32 mem_size; /* mem_size for non-struct typed var */ 532 }; 533 } btf_var; 534 /* if instruction is a call to bpf_loop this field tracks 535 * the state of the relevant registers to make decision about inlining 536 */ 537 struct bpf_loop_inline_state loop_inline_state; 538 }; 539 union { 540 /* remember the size of type passed to bpf_obj_new to rewrite R1 */ 541 u64 obj_new_size; 542 /* remember the offset of node field within type to rewrite */ 543 u64 insert_off; 544 }; 545 struct btf_struct_meta *kptr_struct_meta; 546 u64 map_key_state; /* constant (32 bit) key tracking for maps */ 547 int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ 548 u32 seen; /* this insn was processed by the verifier at env->pass_cnt */ 549 bool sanitize_stack_spill; /* subject to Spectre v4 sanitation */ 550 bool zext_dst; /* this insn zero extends dst reg */ 551 bool needs_zext; /* alu op needs to clear upper bits */ 552 bool storage_get_func_atomic; /* bpf_*_storage_get() with atomic memory alloc */ 553 bool is_iter_next; /* bpf_iter_<type>_next() kfunc call */ 554 bool call_with_percpu_alloc_ptr; /* {this,per}_cpu_ptr() with prog percpu alloc */ 555 u8 alu_state; /* used in combination with alu_limit */ 556 557 /* below fields are initialized once */ 558 unsigned int orig_idx; /* original instruction index */ 559 bool jmp_point; 560 bool prune_point; 561 /* ensure we check state equivalence and save state checkpoint and 562 * this instruction, regardless of any heuristics 563 */ 564 bool force_checkpoint; 565 /* true if instruction is a call to a helper function that 566 * accepts callback function as a parameter. 567 */ 568 bool calls_callback; 569}; 570 571#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ 572#define MAX_USED_BTFS 64 /* max number of BTFs accessed by one BPF program */ 573 574#define BPF_VERIFIER_TMP_LOG_SIZE 1024 575 576struct bpf_verifier_log { 577 /* Logical start and end positions of a "log window" of the verifier log. 578 * start_pos == 0 means we haven't truncated anything. 579 * Once truncation starts to happen, start_pos + len_total == end_pos, 580 * except during log reset situations, in which (end_pos - start_pos) 581 * might get smaller than len_total (see bpf_vlog_reset()). 582 * Generally, (end_pos - start_pos) gives number of useful data in 583 * user log buffer. 584 */ 585 u64 start_pos; 586 u64 end_pos; 587 char __user *ubuf; 588 u32 level; 589 u32 len_total; 590 u32 len_max; 591 char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; 592}; 593 594#define BPF_LOG_LEVEL1 1 595#define BPF_LOG_LEVEL2 2 596#define BPF_LOG_STATS 4 597#define BPF_LOG_FIXED 8 598#define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2) 599#define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS | BPF_LOG_FIXED) 600#define BPF_LOG_KERNEL (BPF_LOG_MASK + 1) /* kernel internal flag */ 601#define BPF_LOG_MIN_ALIGNMENT 8U 602#define BPF_LOG_ALIGNMENT 40U 603 604static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) 605{ 606 return log && log->level; 607} 608 609#define BPF_MAX_SUBPROGS 256 610 611struct bpf_subprog_arg_info { 612 enum bpf_arg_type arg_type; 613 union { 614 u32 mem_size; 615 u32 btf_id; 616 }; 617}; 618 619struct bpf_subprog_info { 620 /* 'start' has to be the first field otherwise find_subprog() won't work */ 621 u32 start; /* insn idx of function entry point */ 622 u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ 623 u16 stack_depth; /* max. stack depth used by this function */ 624 u16 stack_extra; 625 bool has_tail_call: 1; 626 bool tail_call_reachable: 1; 627 bool has_ld_abs: 1; 628 bool is_cb: 1; 629 bool is_async_cb: 1; 630 bool is_exception_cb: 1; 631 bool args_cached: 1; 632 633 u8 arg_cnt; 634 struct bpf_subprog_arg_info args[MAX_BPF_FUNC_REG_ARGS]; 635}; 636 637struct bpf_verifier_env; 638 639struct backtrack_state { 640 struct bpf_verifier_env *env; 641 u32 frame; 642 u32 reg_masks[MAX_CALL_FRAMES]; 643 u64 stack_masks[MAX_CALL_FRAMES]; 644}; 645 646struct bpf_id_pair { 647 u32 old; 648 u32 cur; 649}; 650 651struct bpf_idmap { 652 u32 tmp_id_gen; 653 struct bpf_id_pair map[BPF_ID_MAP_SIZE]; 654}; 655 656struct bpf_idset { 657 u32 count; 658 u32 ids[BPF_ID_MAP_SIZE]; 659}; 660 661/* single container for all structs 662 * one verifier_env per bpf_check() call 663 */ 664struct bpf_verifier_env { 665 u32 insn_idx; 666 u32 prev_insn_idx; 667 struct bpf_prog *prog; /* eBPF program being verified */ 668 const struct bpf_verifier_ops *ops; 669 struct module *attach_btf_mod; /* The owner module of prog->aux->attach_btf */ 670 struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ 671 int stack_size; /* number of states to be processed */ 672 bool strict_alignment; /* perform strict pointer alignment checks */ 673 bool test_state_freq; /* test verifier with different pruning frequency */ 674 bool test_reg_invariants; /* fail verification on register invariants violations */ 675 struct bpf_verifier_state *cur_state; /* current verifier state */ 676 struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ 677 struct bpf_verifier_state_list *free_list; 678 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ 679 struct btf_mod_pair used_btfs[MAX_USED_BTFS]; /* array of BTF's used by BPF program */ 680 u32 used_map_cnt; /* number of used maps */ 681 u32 used_btf_cnt; /* number of used BTF objects */ 682 u32 id_gen; /* used to generate unique reg IDs */ 683 u32 hidden_subprog_cnt; /* number of hidden subprogs */ 684 int exception_callback_subprog; 685 bool explore_alu_limits; 686 bool allow_ptr_leaks; 687 /* Allow access to uninitialized stack memory. Writes with fixed offset are 688 * always allowed, so this refers to reads (with fixed or variable offset), 689 * to writes with variable offset and to indirect (helper) accesses. 690 */ 691 bool allow_uninit_stack; 692 bool bpf_capable; 693 bool bypass_spec_v1; 694 bool bypass_spec_v4; 695 bool seen_direct_write; 696 bool seen_exception; 697 struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ 698 const struct bpf_line_info *prev_linfo; 699 struct bpf_verifier_log log; 700 struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 2]; /* max + 2 for the fake and exception subprogs */ 701 union { 702 struct bpf_idmap idmap_scratch; 703 struct bpf_idset idset_scratch; 704 }; 705 struct { 706 int *insn_state; 707 int *insn_stack; 708 int cur_stack; 709 } cfg; 710 struct backtrack_state bt; 711 struct bpf_jmp_history_entry *cur_hist_ent; 712 u32 pass_cnt; /* number of times do_check() was called */ 713 u32 subprog_cnt; 714 /* number of instructions analyzed by the verifier */ 715 u32 prev_insn_processed, insn_processed; 716 /* number of jmps, calls, exits analyzed so far */ 717 u32 prev_jmps_processed, jmps_processed; 718 /* total verification time */ 719 u64 verification_time; 720 /* maximum number of verifier states kept in 'branching' instructions */ 721 u32 max_states_per_insn; 722 /* total number of allocated verifier states */ 723 u32 total_states; 724 /* some states are freed during program analysis. 725 * this is peak number of states. this number dominates kernel 726 * memory consumption during verification 727 */ 728 u32 peak_states; 729 /* longest register parentage chain walked for liveness marking */ 730 u32 longest_mark_read_walk; 731 bpfptr_t fd_array; 732 733 /* bit mask to keep track of whether a register has been accessed 734 * since the last time the function state was printed 735 */ 736 u32 scratched_regs; 737 /* Same as scratched_regs but for stack slots */ 738 u64 scratched_stack_slots; 739 u64 prev_log_pos, prev_insn_print_pos; 740 /* buffer used to generate temporary string representations, 741 * e.g., in reg_type_str() to generate reg_type string 742 */ 743 char tmp_str_buf[TMP_STR_BUF_LEN]; 744}; 745 746static inline struct bpf_func_info_aux *subprog_aux(struct bpf_verifier_env *env, int subprog) 747{ 748 return &env->prog->aux->func_info_aux[subprog]; 749} 750 751static inline struct bpf_subprog_info *subprog_info(struct bpf_verifier_env *env, int subprog) 752{ 753 return &env->subprog_info[subprog]; 754} 755 756__printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log, 757 const char *fmt, va_list args); 758__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, 759 const char *fmt, ...); 760__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, 761 const char *fmt, ...); 762int bpf_vlog_init(struct bpf_verifier_log *log, u32 log_level, 763 char __user *log_buf, u32 log_size); 764void bpf_vlog_reset(struct bpf_verifier_log *log, u64 new_pos); 765int bpf_vlog_finalize(struct bpf_verifier_log *log, u32 *log_size_actual); 766 767__printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env, 768 u32 insn_off, 769 const char *prefix_fmt, ...); 770 771static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env) 772{ 773 struct bpf_verifier_state *cur = env->cur_state; 774 775 return cur->frame[cur->curframe]; 776} 777 778static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) 779{ 780 return cur_func(env)->regs; 781} 782 783int bpf_prog_offload_verifier_prep(struct bpf_prog *prog); 784int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, 785 int insn_idx, int prev_insn_idx); 786int bpf_prog_offload_finalize(struct bpf_verifier_env *env); 787void 788bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, 789 struct bpf_insn *insn); 790void 791bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); 792 793/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ 794static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, 795 struct btf *btf, u32 btf_id) 796{ 797 if (tgt_prog) 798 return ((u64)tgt_prog->aux->id << 32) | btf_id; 799 else 800 return ((u64)btf_obj_id(btf) << 32) | 0x80000000 | btf_id; 801} 802 803/* unpack the IDs from the key as constructed above */ 804static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id) 805{ 806 if (obj_id) 807 *obj_id = key >> 32; 808 if (btf_id) 809 *btf_id = key & 0x7FFFFFFF; 810} 811 812int bpf_check_attach_target(struct bpf_verifier_log *log, 813 const struct bpf_prog *prog, 814 const struct bpf_prog *tgt_prog, 815 u32 btf_id, 816 struct bpf_attach_target_info *tgt_info); 817void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); 818 819int mark_chain_precision(struct bpf_verifier_env *env, int regno); 820 821#define BPF_BASE_TYPE_MASK GENMASK(BPF_BASE_TYPE_BITS - 1, 0) 822 823/* extract base type from bpf_{arg, return, reg}_type. */ 824static inline u32 base_type(u32 type) 825{ 826 return type & BPF_BASE_TYPE_MASK; 827} 828 829/* extract flags from an extended type. See bpf_type_flag in bpf.h. */ 830static inline u32 type_flag(u32 type) 831{ 832 return type & ~BPF_BASE_TYPE_MASK; 833} 834 835/* only use after check_attach_btf_id() */ 836static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog) 837{ 838 return prog->type == BPF_PROG_TYPE_EXT ? 839 prog->aux->dst_prog->type : prog->type; 840} 841 842static inline bool bpf_prog_check_recur(const struct bpf_prog *prog) 843{ 844 switch (resolve_prog_type(prog)) { 845 case BPF_PROG_TYPE_TRACING: 846 return prog->expected_attach_type != BPF_TRACE_ITER; 847 case BPF_PROG_TYPE_STRUCT_OPS: 848 case BPF_PROG_TYPE_LSM: 849 return false; 850 default: 851 return true; 852 } 853} 854 855#define BPF_REG_TRUSTED_MODIFIERS (MEM_ALLOC | PTR_TRUSTED | NON_OWN_REF) 856 857static inline bool bpf_type_has_unsafe_modifiers(u32 type) 858{ 859 return type_flag(type) & ~BPF_REG_TRUSTED_MODIFIERS; 860} 861 862static inline bool type_is_ptr_alloc_obj(u32 type) 863{ 864 return base_type(type) == PTR_TO_BTF_ID && type_flag(type) & MEM_ALLOC; 865} 866 867static inline bool type_is_non_owning_ref(u32 type) 868{ 869 return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF; 870} 871 872static inline bool type_is_pkt_pointer(enum bpf_reg_type type) 873{ 874 type = base_type(type); 875 return type == PTR_TO_PACKET || 876 type == PTR_TO_PACKET_META; 877} 878 879static inline bool type_is_sk_pointer(enum bpf_reg_type type) 880{ 881 return type == PTR_TO_SOCKET || 882 type == PTR_TO_SOCK_COMMON || 883 type == PTR_TO_TCP_SOCK || 884 type == PTR_TO_XDP_SOCK; 885} 886 887static inline void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno) 888{ 889 env->scratched_regs |= 1U << regno; 890} 891 892static inline void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi) 893{ 894 env->scratched_stack_slots |= 1ULL << spi; 895} 896 897static inline bool reg_scratched(const struct bpf_verifier_env *env, u32 regno) 898{ 899 return (env->scratched_regs >> regno) & 1; 900} 901 902static inline bool stack_slot_scratched(const struct bpf_verifier_env *env, u64 regno) 903{ 904 return (env->scratched_stack_slots >> regno) & 1; 905} 906 907static inline bool verifier_state_scratched(const struct bpf_verifier_env *env) 908{ 909 return env->scratched_regs || env->scratched_stack_slots; 910} 911 912static inline void mark_verifier_state_clean(struct bpf_verifier_env *env) 913{ 914 env->scratched_regs = 0U; 915 env->scratched_stack_slots = 0ULL; 916} 917 918/* Used for printing the entire verifier state. */ 919static inline void mark_verifier_state_scratched(struct bpf_verifier_env *env) 920{ 921 env->scratched_regs = ~0U; 922 env->scratched_stack_slots = ~0ULL; 923} 924 925static inline bool bpf_stack_narrow_access_ok(int off, int fill_size, int spill_size) 926{ 927#ifdef __BIG_ENDIAN 928 off -= spill_size - fill_size; 929#endif 930 931 return !(off % BPF_REG_SIZE); 932} 933 934const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type); 935const char *dynptr_type_str(enum bpf_dynptr_type type); 936const char *iter_type_str(const struct btf *btf, u32 btf_id); 937const char *iter_state_str(enum bpf_iter_state state); 938 939void print_verifier_state(struct bpf_verifier_env *env, 940 const struct bpf_func_state *state, bool print_all); 941void print_insn_state(struct bpf_verifier_env *env, const struct bpf_func_state *state); 942 943#endif /* _LINUX_BPF_VERIFIER_H */ 944