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 */
40 enum 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 */
54 struct 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
67 enum bpf_iter_state {
68 BPF_ITER_STATE_INVALID, /* for non-first slot */
69 BPF_ITER_STATE_ACTIVE,
70 BPF_ITER_STATE_DRAINED,
71 };
72
73 struct 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
230 enum 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
251 struct bpf_stack_state {
252 struct bpf_reg_state spilled_ptr;
253 u8 slot_type[BPF_REG_SIZE];
254 };
255
256 struct 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
278 /* state of the program:
279 * type of all registers and stack info
280 */
281 struct bpf_func_state {
282 struct bpf_reg_state regs[MAX_BPF_REG];
283 /* index of call instruction that called into this func */
284 int callsite;
285 /* stack frame number of this function state from pov of
286 * enclosing bpf_verifier_state.
287 * 0 = main function, 1 = first callee.
288 */
289 u32 frameno;
290 /* subprog number == index within subprog_info
291 * zero == main subprog
292 */
293 u32 subprogno;
294 /* Every bpf_timer_start will increment async_entry_cnt.
295 * It's used to distinguish:
296 * void foo(void) { for(;;); }
297 * void foo(void) { bpf_timer_set_callback(,foo); }
298 */
299 u32 async_entry_cnt;
300 bool in_callback_fn;
301 struct tnum callback_ret_range;
302 bool in_async_callback_fn;
303 /* For callback calling functions that limit number of possible
304 * callback executions (e.g. bpf_loop) keeps track of current
305 * simulated iteration number.
306 * Value in frame N refers to number of times callback with frame
307 * N+1 was simulated, e.g. for the following call:
308 *
309 * bpf_loop(..., fn, ...); | suppose current frame is N
310 * | fn would be simulated in frame N+1
311 * | number of simulations is tracked in frame N
312 */
313 u32 callback_depth;
314
315 /* The following fields should be last. See copy_func_state() */
316 int acquired_refs;
317 struct bpf_reference_state *refs;
318 int allocated_stack;
319 struct bpf_stack_state *stack;
320 };
321
322 struct bpf_idx_pair {
323 u32 prev_idx;
324 u32 idx;
325 };
326
327 #define MAX_CALL_FRAMES 8
328 /* Maximum number of register states that can exist at once */
329 #define BPF_ID_MAP_SIZE ((MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) * MAX_CALL_FRAMES)
330 struct bpf_verifier_state {
331 /* call stack tracking */
332 struct bpf_func_state *frame[MAX_CALL_FRAMES];
333 struct bpf_verifier_state *parent;
334 /*
335 * 'branches' field is the number of branches left to explore:
336 * 0 - all possible paths from this state reached bpf_exit or
337 * were safely pruned
338 * 1 - at least one path is being explored.
339 * This state hasn't reached bpf_exit
340 * 2 - at least two paths are being explored.
341 * This state is an immediate parent of two children.
342 * One is fallthrough branch with branches==1 and another
343 * state is pushed into stack (to be explored later) also with
344 * branches==1. The parent of this state has branches==1.
345 * The verifier state tree connected via 'parent' pointer looks like:
346 * 1
347 * 1
348 * 2 -> 1 (first 'if' pushed into stack)
349 * 1
350 * 2 -> 1 (second 'if' pushed into stack)
351 * 1
352 * 1
353 * 1 bpf_exit.
354 *
355 * Once do_check() reaches bpf_exit, it calls update_branch_counts()
356 * and the verifier state tree will look:
357 * 1
358 * 1
359 * 2 -> 1 (first 'if' pushed into stack)
360 * 1
361 * 1 -> 1 (second 'if' pushed into stack)
362 * 0
363 * 0
364 * 0 bpf_exit.
365 * After pop_stack() the do_check() will resume at second 'if'.
366 *
367 * If is_state_visited() sees a state with branches > 0 it means
368 * there is a loop. If such state is exactly equal to the current state
369 * it's an infinite loop. Note states_equal() checks for states
370 * equivalency, so two states being 'states_equal' does not mean
371 * infinite loop. The exact comparison is provided by
372 * states_maybe_looping() function. It's a stronger pre-check and
373 * much faster than states_equal().
374 *
375 * This algorithm may not find all possible infinite loops or
376 * loop iteration count may be too high.
377 * In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in.
378 */
379 u32 branches;
380 u32 insn_idx;
381 u32 curframe;
382
383 struct bpf_active_lock active_lock;
384 bool speculative;
385 bool active_rcu_lock;
386 /* If this state was ever pointed-to by other state's loop_entry field
387 * this flag would be set to true. Used to avoid freeing such states
388 * while they are still in use.
389 */
390 bool used_as_loop_entry;
391
392 /* first and last insn idx of this verifier state */
393 u32 first_insn_idx;
394 u32 last_insn_idx;
395 /* If this state is a part of states loop this field points to some
396 * parent of this state such that:
397 * - it is also a member of the same states loop;
398 * - DFS states traversal starting from initial state visits loop_entry
399 * state before this state.
400 * Used to compute topmost loop entry for state loops.
401 * State loops might appear because of open coded iterators logic.
402 * See get_loop_entry() for more information.
403 */
404 struct bpf_verifier_state *loop_entry;
405 /* jmp history recorded from first to last.
406 * backtracking is using it to go from last to first.
407 * For most states jmp_history_cnt is [0-3].
408 * For loops can go up to ~40.
409 */
410 struct bpf_idx_pair *jmp_history;
411 u32 jmp_history_cnt;
412 u32 dfs_depth;
413 u32 callback_unroll_depth;
414 };
415
416 #define bpf_get_spilled_reg(slot, frame) \
417 (((slot < frame->allocated_stack / BPF_REG_SIZE) && \
418 (frame->stack[slot].slot_type[0] == STACK_SPILL)) \
419 ? &frame->stack[slot].spilled_ptr : NULL)
420
421 /* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
422 #define bpf_for_each_spilled_reg(iter, frame, reg) \
423 for (iter = 0, reg = bpf_get_spilled_reg(iter, frame); \
424 iter < frame->allocated_stack / BPF_REG_SIZE; \
425 iter++, reg = bpf_get_spilled_reg(iter, frame))
426
427 /* Invoke __expr over regsiters in __vst, setting __state and __reg */
428 #define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr) \
429 ({ \
430 struct bpf_verifier_state *___vstate = __vst; \
431 int ___i, ___j; \
432 for (___i = 0; ___i <= ___vstate->curframe; ___i++) { \
433 struct bpf_reg_state *___regs; \
434 __state = ___vstate->frame[___i]; \
435 ___regs = __state->regs; \
436 for (___j = 0; ___j < MAX_BPF_REG; ___j++) { \
437 __reg = &___regs[___j]; \
438 (void)(__expr); \
439 } \
440 bpf_for_each_spilled_reg(___j, __state, __reg) { \
441 if (!__reg) \
442 continue; \
443 (void)(__expr); \
444 } \
445 } \
446 })
447
448 /* linked list of verifier states used to prune search */
449 struct bpf_verifier_state_list {
450 struct bpf_verifier_state state;
451 struct bpf_verifier_state_list *next;
452 int miss_cnt, hit_cnt;
453 };
454
455 struct bpf_loop_inline_state {
456 unsigned int initialized:1; /* set to true upon first entry */
457 unsigned int fit_for_inline:1; /* true if callback function is the same
458 * at each call and flags are always zero
459 */
460 u32 callback_subprogno; /* valid when fit_for_inline is true */
461 };
462
463 /* Possible states for alu_state member. */
464 #define BPF_ALU_SANITIZE_SRC (1U << 0)
465 #define BPF_ALU_SANITIZE_DST (1U << 1)
466 #define BPF_ALU_NEG_VALUE (1U << 2)
467 #define BPF_ALU_NON_POINTER (1U << 3)
468 #define BPF_ALU_IMMEDIATE (1U << 4)
469 #define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \
470 BPF_ALU_SANITIZE_DST)
471
472 struct bpf_insn_aux_data {
473 union {
474 enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
475 unsigned long map_ptr_state; /* pointer/poison value for maps */
476 s32 call_imm; /* saved imm field of call insn */
477 u32 alu_limit; /* limit for add/sub register with pointer */
478 struct {
479 u32 map_index; /* index into used_maps[] */
480 u32 map_off; /* offset from value base address */
481 };
482 struct {
483 enum bpf_reg_type reg_type; /* type of pseudo_btf_id */
484 union {
485 struct {
486 struct btf *btf;
487 u32 btf_id; /* btf_id for struct typed var */
488 };
489 u32 mem_size; /* mem_size for non-struct typed var */
490 };
491 } btf_var;
492 /* if instruction is a call to bpf_loop this field tracks
493 * the state of the relevant registers to make decision about inlining
494 */
495 struct bpf_loop_inline_state loop_inline_state;
496 };
497 union {
498 /* remember the size of type passed to bpf_obj_new to rewrite R1 */
499 u64 obj_new_size;
500 /* remember the offset of node field within type to rewrite */
501 u64 insert_off;
502 };
503 struct btf_struct_meta *kptr_struct_meta;
504 u64 map_key_state; /* constant (32 bit) key tracking for maps */
505 int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
506 u32 seen; /* this insn was processed by the verifier at env->pass_cnt */
507 bool sanitize_stack_spill; /* subject to Spectre v4 sanitation */
508 bool zext_dst; /* this insn zero extends dst reg */
509 bool storage_get_func_atomic; /* bpf_*_storage_get() with atomic memory alloc */
510 bool is_iter_next; /* bpf_iter_<type>_next() kfunc call */
511 u8 alu_state; /* used in combination with alu_limit */
512
513 /* below fields are initialized once */
514 unsigned int orig_idx; /* original instruction index */
515 bool jmp_point;
516 bool prune_point;
517 /* ensure we check state equivalence and save state checkpoint and
518 * this instruction, regardless of any heuristics
519 */
520 bool force_checkpoint;
521 /* true if instruction is a call to a helper function that
522 * accepts callback function as a parameter.
523 */
524 bool calls_callback;
525 };
526
527 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
528 #define MAX_USED_BTFS 64 /* max number of BTFs accessed by one BPF program */
529
530 #define BPF_VERIFIER_TMP_LOG_SIZE 1024
531
532 struct bpf_verifier_log {
533 /* Logical start and end positions of a "log window" of the verifier log.
534 * start_pos == 0 means we haven't truncated anything.
535 * Once truncation starts to happen, start_pos + len_total == end_pos,
536 * except during log reset situations, in which (end_pos - start_pos)
537 * might get smaller than len_total (see bpf_vlog_reset()).
538 * Generally, (end_pos - start_pos) gives number of useful data in
539 * user log buffer.
540 */
541 u64 start_pos;
542 u64 end_pos;
543 char __user *ubuf;
544 u32 level;
545 u32 len_total;
546 u32 len_max;
547 char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
548 };
549
550 #define BPF_LOG_LEVEL1 1
551 #define BPF_LOG_LEVEL2 2
552 #define BPF_LOG_STATS 4
553 #define BPF_LOG_FIXED 8
554 #define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2)
555 #define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS | BPF_LOG_FIXED)
556 #define BPF_LOG_KERNEL (BPF_LOG_MASK + 1) /* kernel internal flag */
557 #define BPF_LOG_MIN_ALIGNMENT 8U
558 #define BPF_LOG_ALIGNMENT 40U
559
bpf_verifier_log_needed(const struct bpf_verifier_log * log)560 static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
561 {
562 return log && log->level;
563 }
564
565 #define BPF_MAX_SUBPROGS 256
566
567 struct bpf_subprog_info {
568 /* 'start' has to be the first field otherwise find_subprog() won't work */
569 u32 start; /* insn idx of function entry point */
570 u32 linfo_idx; /* The idx to the main_prog->aux->linfo */
571 u16 stack_depth; /* max. stack depth used by this function */
572 bool has_tail_call;
573 bool tail_call_reachable;
574 bool has_ld_abs;
575 bool is_async_cb;
576 };
577
578 struct bpf_verifier_env;
579
580 struct backtrack_state {
581 struct bpf_verifier_env *env;
582 u32 frame;
583 u32 reg_masks[MAX_CALL_FRAMES];
584 u64 stack_masks[MAX_CALL_FRAMES];
585 };
586
587 struct bpf_id_pair {
588 u32 old;
589 u32 cur;
590 };
591
592 struct bpf_idmap {
593 u32 tmp_id_gen;
594 struct bpf_id_pair map[BPF_ID_MAP_SIZE];
595 };
596
597 struct bpf_idset {
598 u32 count;
599 u32 ids[BPF_ID_MAP_SIZE];
600 };
601
602 /* single container for all structs
603 * one verifier_env per bpf_check() call
604 */
605 struct bpf_verifier_env {
606 u32 insn_idx;
607 u32 prev_insn_idx;
608 struct bpf_prog *prog; /* eBPF program being verified */
609 const struct bpf_verifier_ops *ops;
610 struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
611 int stack_size; /* number of states to be processed */
612 bool strict_alignment; /* perform strict pointer alignment checks */
613 bool test_state_freq; /* test verifier with different pruning frequency */
614 struct bpf_verifier_state *cur_state; /* current verifier state */
615 struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
616 struct bpf_verifier_state_list *free_list;
617 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
618 struct btf_mod_pair used_btfs[MAX_USED_BTFS]; /* array of BTF's used by BPF program */
619 u32 used_map_cnt; /* number of used maps */
620 u32 used_btf_cnt; /* number of used BTF objects */
621 u32 id_gen; /* used to generate unique reg IDs */
622 bool explore_alu_limits;
623 bool allow_ptr_leaks;
624 bool allow_uninit_stack;
625 bool bpf_capable;
626 bool bypass_spec_v1;
627 bool bypass_spec_v4;
628 bool seen_direct_write;
629 struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
630 const struct bpf_line_info *prev_linfo;
631 struct bpf_verifier_log log;
632 struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
633 union {
634 struct bpf_idmap idmap_scratch;
635 struct bpf_idset idset_scratch;
636 };
637 struct {
638 int *insn_state;
639 int *insn_stack;
640 int cur_stack;
641 } cfg;
642 struct backtrack_state bt;
643 u32 pass_cnt; /* number of times do_check() was called */
644 u32 subprog_cnt;
645 /* number of instructions analyzed by the verifier */
646 u32 prev_insn_processed, insn_processed;
647 /* number of jmps, calls, exits analyzed so far */
648 u32 prev_jmps_processed, jmps_processed;
649 /* total verification time */
650 u64 verification_time;
651 /* maximum number of verifier states kept in 'branching' instructions */
652 u32 max_states_per_insn;
653 /* total number of allocated verifier states */
654 u32 total_states;
655 /* some states are freed during program analysis.
656 * this is peak number of states. this number dominates kernel
657 * memory consumption during verification
658 */
659 u32 peak_states;
660 /* longest register parentage chain walked for liveness marking */
661 u32 longest_mark_read_walk;
662 bpfptr_t fd_array;
663
664 /* bit mask to keep track of whether a register has been accessed
665 * since the last time the function state was printed
666 */
667 u32 scratched_regs;
668 /* Same as scratched_regs but for stack slots */
669 u64 scratched_stack_slots;
670 u64 prev_log_pos, prev_insn_print_pos;
671 /* buffer used to generate temporary string representations,
672 * e.g., in reg_type_str() to generate reg_type string
673 */
674 char tmp_str_buf[TMP_STR_BUF_LEN];
675 };
676
677 __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
678 const char *fmt, va_list args);
679 __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
680 const char *fmt, ...);
681 __printf(2, 3) void bpf_log(struct bpf_verifier_log *log,
682 const char *fmt, ...);
683 int bpf_vlog_init(struct bpf_verifier_log *log, u32 log_level,
684 char __user *log_buf, u32 log_size);
685 void bpf_vlog_reset(struct bpf_verifier_log *log, u64 new_pos);
686 int bpf_vlog_finalize(struct bpf_verifier_log *log, u32 *log_size_actual);
687
cur_func(struct bpf_verifier_env * env)688 static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env)
689 {
690 struct bpf_verifier_state *cur = env->cur_state;
691
692 return cur->frame[cur->curframe];
693 }
694
cur_regs(struct bpf_verifier_env * env)695 static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
696 {
697 return cur_func(env)->regs;
698 }
699
700 int bpf_prog_offload_verifier_prep(struct bpf_prog *prog);
701 int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
702 int insn_idx, int prev_insn_idx);
703 int bpf_prog_offload_finalize(struct bpf_verifier_env *env);
704 void
705 bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
706 struct bpf_insn *insn);
707 void
708 bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
709
710 int check_ptr_off_reg(struct bpf_verifier_env *env,
711 const struct bpf_reg_state *reg, int regno);
712 int check_func_arg_reg_off(struct bpf_verifier_env *env,
713 const struct bpf_reg_state *reg, int regno,
714 enum bpf_arg_type arg_type);
715 int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
716 u32 regno, u32 mem_size);
717
718 /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */
bpf_trampoline_compute_key(const struct bpf_prog * tgt_prog,struct btf * btf,u32 btf_id)719 static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
720 struct btf *btf, u32 btf_id)
721 {
722 if (tgt_prog)
723 return ((u64)tgt_prog->aux->id << 32) | btf_id;
724 else
725 return ((u64)btf_obj_id(btf) << 32) | 0x80000000 | btf_id;
726 }
727
728 /* unpack the IDs from the key as constructed above */
bpf_trampoline_unpack_key(u64 key,u32 * obj_id,u32 * btf_id)729 static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id)
730 {
731 if (obj_id)
732 *obj_id = key >> 32;
733 if (btf_id)
734 *btf_id = key & 0x7FFFFFFF;
735 }
736
737 int bpf_check_attach_target(struct bpf_verifier_log *log,
738 const struct bpf_prog *prog,
739 const struct bpf_prog *tgt_prog,
740 u32 btf_id,
741 struct bpf_attach_target_info *tgt_info);
742 void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab);
743
744 int mark_chain_precision(struct bpf_verifier_env *env, int regno);
745
746 #define BPF_BASE_TYPE_MASK GENMASK(BPF_BASE_TYPE_BITS - 1, 0)
747
748 /* extract base type from bpf_{arg, return, reg}_type. */
base_type(u32 type)749 static inline u32 base_type(u32 type)
750 {
751 return type & BPF_BASE_TYPE_MASK;
752 }
753
754 /* extract flags from an extended type. See bpf_type_flag in bpf.h. */
type_flag(u32 type)755 static inline u32 type_flag(u32 type)
756 {
757 return type & ~BPF_BASE_TYPE_MASK;
758 }
759
760 /* only use after check_attach_btf_id() */
resolve_prog_type(const struct bpf_prog * prog)761 static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog)
762 {
763 return prog->type == BPF_PROG_TYPE_EXT ?
764 prog->aux->dst_prog->type : prog->type;
765 }
766
bpf_prog_check_recur(const struct bpf_prog * prog)767 static inline bool bpf_prog_check_recur(const struct bpf_prog *prog)
768 {
769 switch (resolve_prog_type(prog)) {
770 case BPF_PROG_TYPE_TRACING:
771 return prog->expected_attach_type != BPF_TRACE_ITER;
772 case BPF_PROG_TYPE_STRUCT_OPS:
773 case BPF_PROG_TYPE_LSM:
774 return false;
775 default:
776 return true;
777 }
778 }
779
780 #define BPF_REG_TRUSTED_MODIFIERS (MEM_ALLOC | PTR_TRUSTED | NON_OWN_REF)
781
bpf_type_has_unsafe_modifiers(u32 type)782 static inline bool bpf_type_has_unsafe_modifiers(u32 type)
783 {
784 return type_flag(type) & ~BPF_REG_TRUSTED_MODIFIERS;
785 }
786
787 #endif /* _LINUX_BPF_VERIFIER_H */
788