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

source code of linux/include/linux/bpf_verifier.h