include/linux/bpf_verifier.h - third_party/kernel - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
  */
 #ifndef _LINUX_BPF_VERIFIER_H
 #define _LINUX_BPF_VERIFIER_H 1

 #include <linux/bpf.h> /* for enum bpf_reg_type */
 #include <linux/filter.h> /* for MAX_BPF_STACK */
 #include <linux/tnum.h>

 /* Maximum variable offset umax_value permitted when resolving memory accesses.
  * In practice this is far bigger than any realistic pointer offset; this limit
  * ensures that umax_value + (int)off + (int)size cannot overflow a u64.
  */
 #define BPF_MAX_VAR_OFF	(1 << 29)
 /* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO].  This ensures
  * that converting umax_value to int cannot overflow.
  */
 #define BPF_MAX_VAR_SIZ	(1 << 29)

 /* Liveness marks, used for registers and spilled-regs (in stack slots).
  * Read marks propagate upwards until they find a write mark; they record that
  * "one of this state's descendants read this reg" (and therefore the reg is
  * relevant for states_equal() checks).
  * Write marks collect downwards and do not propagate; they record that "the
  * straight-line code that reached this state (from its parent) wrote this reg"
  * (and therefore that reads propagated from this state or its descendants
  * should not propagate to its parent).
  * A state with a write mark can receive read marks; it just won't propagate
  * them to its parent, since the write mark is a property, not of the state,
  * but of the link between it and its parent.  See mark_reg_read() and
  * mark_stack_slot_read() in kernel/bpf/verifier.c.
  */
 enum bpf_reg_liveness {
 	REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */
 	REG_LIVE_READ32 = 0x1, /* reg was read, so we're sensitive to initial value */
 	REG_LIVE_READ64 = 0x2, /* likewise, but full 64-bit content matters */
 	REG_LIVE_READ = REG_LIVE_READ32 | REG_LIVE_READ64,
 	REG_LIVE_WRITTEN = 0x4, /* reg was written first, screening off later reads */
 	REG_LIVE_DONE = 0x8, /* liveness won't be updating this register anymore */
 };

 struct bpf_reg_state {
 	/* Ordering of fields matters.  See states_equal() */
 	enum bpf_reg_type type;
 	union {
 		/* valid when type == PTR_TO_PACKET */
 		u16 range;

 		/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
 		 *   PTR_TO_MAP_VALUE_OR_NULL
 		 */
 		struct bpf_map *map_ptr;

 		/* Max size from any of the above. */
 		unsigned long raw;
 	};
 	/* Fixed part of pointer offset, pointer types only */
 	s32 off;
 	/* For PTR_TO_PACKET, used to find other pointers with the same variable
 	 * offset, so they can share range knowledge.
 	 * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
 	 * came from, when one is tested for != NULL.
 	 * For PTR_TO_SOCKET this is used to share which pointers retain the
 	 * same reference to the socket, to determine proper reference freeing.
 	 */
 	u32 id;
 	/* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned
 	 * from a pointer-cast helper, bpf_sk_fullsock() and
 	 * bpf_tcp_sock().
 	 *
 	 * Consider the following where "sk" is a reference counted
 	 * pointer returned from "sk = bpf_sk_lookup_tcp();":
 	 *
 	 * 1: sk = bpf_sk_lookup_tcp();
 	 * 2: if (!sk) { return 0; }
 	 * 3: fullsock = bpf_sk_fullsock(sk);
 	 * 4: if (!fullsock) { bpf_sk_release(sk); return 0; }
 	 * 5: tp = bpf_tcp_sock(fullsock);
 	 * 6: if (!tp) { bpf_sk_release(sk); return 0; }
 	 * 7: bpf_sk_release(sk);
 	 * 8: snd_cwnd = tp->snd_cwnd;  // verifier will complain
 	 *
 	 * After bpf_sk_release(sk) at line 7, both "fullsock" ptr and
 	 * "tp" ptr should be invalidated also.  In order to do that,
 	 * the reg holding "fullsock" and "sk" need to remember
 	 * the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id
 	 * such that the verifier can reset all regs which have
 	 * ref_obj_id matching the sk_reg->id.
 	 *
 	 * sk_reg->ref_obj_id is set to sk_reg->id at line 1.
 	 * sk_reg->id will stay as NULL-marking purpose only.
 	 * After NULL-marking is done, sk_reg->id can be reset to 0.
 	 *
 	 * After "fullsock = bpf_sk_fullsock(sk);" at line 3,
 	 * fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id.
 	 *
 	 * After "tp = bpf_tcp_sock(fullsock);" at line 5,
 	 * tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id
 	 * which is the same as sk_reg->ref_obj_id.
 	 *
 	 * From the verifier perspective, if sk, fullsock and tp
 	 * are not NULL, they are the same ptr with different
 	 * reg->type.  In particular, bpf_sk_release(tp) is also
 	 * allowed and has the same effect as bpf_sk_release(sk).
 	 */
 	u32 ref_obj_id;
 	/* For scalar types (SCALAR_VALUE), this represents our knowledge of
 	 * the actual value.
 	 * For pointer types, this represents the variable part of the offset
 	 * from the pointed-to object, and is shared with all bpf_reg_states
 	 * with the same id as us.
 	 */
 	struct tnum var_off;
 	/* Used to determine if any memory access using this register will
 	 * result in a bad access.
 	 * These refer to the same value as var_off, not necessarily the actual
 	 * contents of the register.
 	 */
 	s64 smin_value; /* minimum possible (s64)value */
 	s64 smax_value; /* maximum possible (s64)value */
 	u64 umin_value; /* minimum possible (u64)value */
 	u64 umax_value; /* maximum possible (u64)value */
 	/* parentage chain for liveness checking */
 	struct bpf_reg_state *parent;
 	/* Inside the callee two registers can be both PTR_TO_STACK like
 	 * R1=fp-8 and R2=fp-8, but one of them points to this function stack
 	 * while another to the caller's stack. To differentiate them 'frameno'
 	 * is used which is an index in bpf_verifier_state->frame[] array
 	 * pointing to bpf_func_state.
 	 */
 	u32 frameno;
 	/* Tracks subreg definition. The stored value is the insn_idx of the
 	 * writing insn. This is safe because subreg_def is used before any insn
 	 * patching which only happens after main verification finished.
 	 */
 	s32 subreg_def;
 	enum bpf_reg_liveness live;
 	/* if (!precise && SCALAR_VALUE) min/max/tnum don't affect safety */
 	bool precise;
 };

 enum bpf_stack_slot_type {
 	STACK_INVALID,    /* nothing was stored in this stack slot */
 	STACK_SPILL,      /* register spilled into stack */
 	STACK_MISC,	  /* BPF program wrote some data into this slot */
 	STACK_ZERO,	  /* BPF program wrote constant zero */
 };

 #define BPF_REG_SIZE 8	/* size of eBPF register in bytes */

 struct bpf_stack_state {
 	struct bpf_reg_state spilled_ptr;
 	u8 slot_type[BPF_REG_SIZE];
 };

 struct bpf_reference_state {
 	/* Track each reference created with a unique id, even if the same
 	 * instruction creates the reference multiple times (eg, via CALL).
 	 */
 	int id;
 	/* Instruction where the allocation of this reference occurred. This
 	 * is used purely to inform the user of a reference leak.
 	 */
 	int insn_idx;
 };

 /* state of the program:
  * type of all registers and stack info
  */
 struct bpf_func_state {
 	struct bpf_reg_state regs[MAX_BPF_REG];
 	/* index of call instruction that called into this func */
 	int callsite;
 	/* stack frame number of this function state from pov of
 	 * enclosing bpf_verifier_state.
 	 * 0 = main function, 1 = first callee.
 	 */
 	u32 frameno;
 	/* subprog number == index within subprog_stack_depth
 	 * zero == main subprog
 	 */
 	u32 subprogno;

 	/* The following fields should be last. See copy_func_state() */
 	int acquired_refs;
 	struct bpf_reference_state *refs;
 	int allocated_stack;
 	struct bpf_stack_state *stack;
 };

 struct bpf_idx_pair {
 	u32 prev_idx;
 	u32 idx;
 };

 #define MAX_CALL_FRAMES 8
 struct bpf_verifier_state {
 	/* call stack tracking */
 	struct bpf_func_state *frame[MAX_CALL_FRAMES];
 	struct bpf_verifier_state *parent;
 	/*
 	 * 'branches' field is the number of branches left to explore:
 	 * 0 - all possible paths from this state reached bpf_exit or
 	 * were safely pruned
 	 * 1 - at least one path is being explored.
 	 * This state hasn't reached bpf_exit
 	 * 2 - at least two paths are being explored.
 	 * This state is an immediate parent of two children.
 	 * One is fallthrough branch with branches==1 and another
 	 * state is pushed into stack (to be explored later) also with
 	 * branches==1. The parent of this state has branches==1.
 	 * The verifier state tree connected via 'parent' pointer looks like:
 	 * 1
 	 * 1
 	 * 2 -> 1 (first 'if' pushed into stack)
 	 * 1
 	 * 2 -> 1 (second 'if' pushed into stack)
 	 * 1
 	 * 1
 	 * 1 bpf_exit.
 	 *
 	 * Once do_check() reaches bpf_exit, it calls update_branch_counts()
 	 * and the verifier state tree will look:
 	 * 1
 	 * 1
 	 * 2 -> 1 (first 'if' pushed into stack)
 	 * 1
 	 * 1 -> 1 (second 'if' pushed into stack)
 	 * 0
 	 * 0
 	 * 0 bpf_exit.
 	 * After pop_stack() the do_check() will resume at second 'if'.
 	 *
 	 * If is_state_visited() sees a state with branches > 0 it means
 	 * there is a loop. If such state is exactly equal to the current state
 	 * it's an infinite loop. Note states_equal() checks for states
 	 * equvalency, so two states being 'states_equal' does not mean
 	 * infinite loop. The exact comparison is provided by
 	 * states_maybe_looping() function. It's a stronger pre-check and
 	 * much faster than states_equal().
 	 *
 	 * This algorithm may not find all possible infinite loops or
 	 * loop iteration count may be too high.
 	 * In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in.
 	 */
 	u32 branches;
 	u32 insn_idx;
 	u32 curframe;
 	u32 active_spin_lock;
 	bool speculative;

 	/* first and last insn idx of this verifier state */
 	u32 first_insn_idx;
 	u32 last_insn_idx;
 	/* jmp history recorded from first to last.
 	 * backtracking is using it to go from last to first.
 	 * For most states jmp_history_cnt is [0-3].
 	 * For loops can go up to ~40.
 	 */
 	struct bpf_idx_pair *jmp_history;
 	u32 jmp_history_cnt;
 };

 #define bpf_get_spilled_reg(slot, frame)				\
 	(((slot < frame->allocated_stack / BPF_REG_SIZE) &&		\
 	  (frame->stack[slot].slot_type[0] == STACK_SPILL))		\
 	 ? &frame->stack[slot].spilled_ptr : NULL)

 /* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
 #define bpf_for_each_spilled_reg(iter, frame, reg)			\
 	for (iter = 0, reg = bpf_get_spilled_reg(iter, frame);		\
 	     iter < frame->allocated_stack / BPF_REG_SIZE;		\
 	     iter++, reg = bpf_get_spilled_reg(iter, frame))

 /* linked list of verifier states used to prune search */
 struct bpf_verifier_state_list {
 	struct bpf_verifier_state state;
 	struct bpf_verifier_state_list *next;
 	int miss_cnt, hit_cnt;
 };

 /* Possible states for alu_state member. */
 #define BPF_ALU_SANITIZE_SRC		1U
 #define BPF_ALU_SANITIZE_DST		2U
 #define BPF_ALU_NEG_VALUE		(1U << 2)
 #define BPF_ALU_NON_POINTER		(1U << 3)
 #define BPF_ALU_SANITIZE		(BPF_ALU_SANITIZE_SRC | \
 					 BPF_ALU_SANITIZE_DST)

 struct bpf_insn_aux_data {
 	union {
 		enum bpf_reg_type ptr_type;	/* pointer type for load/store insns */
 		unsigned long map_state;	/* pointer/poison value for maps */
 		s32 call_imm;			/* saved imm field of call insn */
 		u32 alu_limit;			/* limit for add/sub register with pointer */
 		struct {
 			u32 map_index;		/* index into used_maps[] */
 			u32 map_off;		/* offset from value base address */
 		};
 	};
 	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
 	int sanitize_stack_off; /* stack slot to be cleared */
 	bool seen; /* this insn was processed by the verifier */
 	bool zext_dst; /* this insn zero extends dst reg */
 	u8 alu_state; /* used in combination with alu_limit */
 	bool prune_point;
 	unsigned int orig_idx; /* original instruction index */
 };

 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */

 #define BPF_VERIFIER_TMP_LOG_SIZE	1024

 struct bpf_verifier_log {
 	u32 level;
 	char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
 	char __user *ubuf;
 	u32 len_used;
 	u32 len_total;
 };

 static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log)
 {
 	return log->len_used >= log->len_total - 1;
 }

 #define BPF_LOG_LEVEL1	1
 #define BPF_LOG_LEVEL2	2
 #define BPF_LOG_STATS	4
 #define BPF_LOG_LEVEL	(BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2)
 #define BPF_LOG_MASK	(BPF_LOG_LEVEL | BPF_LOG_STATS)

 static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
 {
 	return log->level && log->ubuf && !bpf_verifier_log_full(log);
 }

 #define BPF_MAX_SUBPROGS 256

 struct bpf_subprog_info {
 	u32 start; /* insn idx of function entry point */
 	u32 linfo_idx; /* The idx to the main_prog->aux->linfo */
 	u16 stack_depth; /* max. stack depth used by this function */
 	bool has_tail_call;
 };

 /* single container for all structs
  * one verifier_env per bpf_check() call
  */
 struct bpf_verifier_env {
 	u32 insn_idx;
 	u32 prev_insn_idx;
 	struct bpf_prog *prog;		/* eBPF program being verified */
 	const struct bpf_verifier_ops *ops;
 	struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
 	int stack_size;			/* number of states to be processed */
 	bool strict_alignment;		/* perform strict pointer alignment checks */
 	bool test_state_freq;		/* test verifier with different pruning frequency */
 	struct bpf_verifier_state *cur_state; /* current verifier state */
 	struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
 	struct bpf_verifier_state_list *free_list;
 	struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
 	u32 used_map_cnt;		/* number of used maps */
 	u32 id_gen;			/* used to generate unique reg IDs */
 	bool allow_ptr_leaks;
 	bool seen_direct_write;
 	struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
 	const struct bpf_line_info *prev_linfo;
 	struct bpf_verifier_log log;
 	struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
 	struct {
 		int *insn_state;
 		int *insn_stack;
 		int cur_stack;
 	} cfg;
 	u32 subprog_cnt;
 	/* number of instructions analyzed by the verifier */
 	u32 prev_insn_processed, insn_processed;
 	/* number of jmps, calls, exits analyzed so far */
 	u32 prev_jmps_processed, jmps_processed;
 	/* total verification time */
 	u64 verification_time;
 	/* maximum number of verifier states kept in 'branching' instructions */
 	u32 max_states_per_insn;
 	/* total number of allocated verifier states */
 	u32 total_states;
 	/* some states are freed during program analysis.
 	 * this is peak number of states. this number dominates kernel
 	 * memory consumption during verification
 	 */
 	u32 peak_states;
 	/* longest register parentage chain walked for liveness marking */
 	u32 longest_mark_read_walk;
 };

 __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
 				      const char *fmt, va_list args);
 __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
 					   const char *fmt, ...);

 static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env)
 {
 	struct bpf_verifier_state *cur = env->cur_state;

 	return cur->frame[cur->curframe];
 }

 static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
 {
 	return cur_func(env)->regs;
 }

 int bpf_prog_offload_verifier_prep(struct bpf_prog *prog);
 int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
 				 int insn_idx, int prev_insn_idx);
 int bpf_prog_offload_finalize(struct bpf_verifier_env *env);
 void
 bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
 			      struct bpf_insn *insn);
 void
 bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);

 #endif /* _LINUX_BPF_VERIFIER_H */
	/* SPDX-License-Identifier: GPL-2.0-only */
	/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
	*/
	#ifndef _LINUX_BPF_VERIFIER_H
	#define _LINUX_BPF_VERIFIER_H 1

	#include <linux/bpf.h> /* for enum bpf_reg_type */
	#include <linux/filter.h> /* for MAX_BPF_STACK */
	#include <linux/tnum.h>

	/* Maximum variable offset umax_value permitted when resolving memory accesses.
	* In practice this is far bigger than any realistic pointer offset; this limit
	* ensures that umax_value + (int)off + (int)size cannot overflow a u64.
	*/
	#define BPF_MAX_VAR_OFF (1 << 29)
	/* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures
	* that converting umax_value to int cannot overflow.
	*/
	#define BPF_MAX_VAR_SIZ (1 << 29)

	/* Liveness marks, used for registers and spilled-regs (in stack slots).
	* Read marks propagate upwards until they find a write mark; they record that
	* "one of this state's descendants read this reg" (and therefore the reg is
	* relevant for states_equal() checks).
	* Write marks collect downwards and do not propagate; they record that "the
	* straight-line code that reached this state (from its parent) wrote this reg"
	* (and therefore that reads propagated from this state or its descendants
	* should not propagate to its parent).
	* A state with a write mark can receive read marks; it just won't propagate
	* them to its parent, since the write mark is a property, not of the state,
	* but of the link between it and its parent. See mark_reg_read() and
	* mark_stack_slot_read() in kernel/bpf/verifier.c.
	*/
	enum bpf_reg_liveness {
	REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */
	REG_LIVE_READ32 = 0x1, /* reg was read, so we're sensitive to initial value */
	REG_LIVE_READ64 = 0x2, /* likewise, but full 64-bit content matters */
	REG_LIVE_READ = REG_LIVE_READ32 \| REG_LIVE_READ64,
	REG_LIVE_WRITTEN = 0x4, /* reg was written first, screening off later reads */
	REG_LIVE_DONE = 0x8, /* liveness won't be updating this register anymore */
	};

	struct bpf_reg_state {
	/* Ordering of fields matters. See states_equal() */
	enum bpf_reg_type type;
	union {
	/* valid when type == PTR_TO_PACKET */
	u16 range;

	/* valid when type == CONST_PTR_TO_MAP \| PTR_TO_MAP_VALUE \|
	* PTR_TO_MAP_VALUE_OR_NULL
	*/
	struct bpf_map *map_ptr;

	/* Max size from any of the above. */
	unsigned long raw;
	};
	/* Fixed part of pointer offset, pointer types only */
	s32 off;
	/* For PTR_TO_PACKET, used to find other pointers with the same variable
	* offset, so they can share range knowledge.
	* For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
	* came from, when one is tested for != NULL.
	* For PTR_TO_SOCKET this is used to share which pointers retain the
	* same reference to the socket, to determine proper reference freeing.
	*/
	u32 id;
	/* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned
	* from a pointer-cast helper, bpf_sk_fullsock() and
	* bpf_tcp_sock().
	*
	* Consider the following where "sk" is a reference counted
	* pointer returned from "sk = bpf_sk_lookup_tcp();":
	*
	* 1: sk = bpf_sk_lookup_tcp();
	* 2: if (!sk) { return 0; }
	* 3: fullsock = bpf_sk_fullsock(sk);
	* 4: if (!fullsock) { bpf_sk_release(sk); return 0; }
	* 5: tp = bpf_tcp_sock(fullsock);
	* 6: if (!tp) { bpf_sk_release(sk); return 0; }
	* 7: bpf_sk_release(sk);
	* 8: snd_cwnd = tp->snd_cwnd; // verifier will complain
	*
	* After bpf_sk_release(sk) at line 7, both "fullsock" ptr and
	* "tp" ptr should be invalidated also. In order to do that,
	* the reg holding "fullsock" and "sk" need to remember
	* the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id
	* such that the verifier can reset all regs which have
	* ref_obj_id matching the sk_reg->id.
	*
	* sk_reg->ref_obj_id is set to sk_reg->id at line 1.
	* sk_reg->id will stay as NULL-marking purpose only.
	* After NULL-marking is done, sk_reg->id can be reset to 0.
	*
	* After "fullsock = bpf_sk_fullsock(sk);" at line 3,
	* fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id.
	*
	* After "tp = bpf_tcp_sock(fullsock);" at line 5,
	* tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id
	* which is the same as sk_reg->ref_obj_id.
	*
	* From the verifier perspective, if sk, fullsock and tp
	* are not NULL, they are the same ptr with different
	* reg->type. In particular, bpf_sk_release(tp) is also
	* allowed and has the same effect as bpf_sk_release(sk).
	*/
	u32 ref_obj_id;
	/* For scalar types (SCALAR_VALUE), this represents our knowledge of
	* the actual value.
	* For pointer types, this represents the variable part of the offset
	* from the pointed-to object, and is shared with all bpf_reg_states
	* with the same id as us.
	*/
	struct tnum var_off;
	/* Used to determine if any memory access using this register will
	* result in a bad access.
	* These refer to the same value as var_off, not necessarily the actual
	* contents of the register.
	*/
	s64 smin_value; /* minimum possible (s64)value */
	s64 smax_value; /* maximum possible (s64)value */
	u64 umin_value; /* minimum possible (u64)value */
	u64 umax_value; /* maximum possible (u64)value */
	/* parentage chain for liveness checking */
	struct bpf_reg_state *parent;
	/* Inside the callee two registers can be both PTR_TO_STACK like
	* R1=fp-8 and R2=fp-8, but one of them points to this function stack
	* while another to the caller's stack. To differentiate them 'frameno'
	* is used which is an index in bpf_verifier_state->frame[] array
	* pointing to bpf_func_state.
	*/
	u32 frameno;
	/* Tracks subreg definition. The stored value is the insn_idx of the
	* writing insn. This is safe because subreg_def is used before any insn
	* patching which only happens after main verification finished.
	*/
	s32 subreg_def;
	enum bpf_reg_liveness live;
	/* if (!precise && SCALAR_VALUE) min/max/tnum don't affect safety */
	bool precise;
	};

	enum bpf_stack_slot_type {
	STACK_INVALID, /* nothing was stored in this stack slot */
	STACK_SPILL, /* register spilled into stack */
	STACK_MISC, /* BPF program wrote some data into this slot */
	STACK_ZERO, /* BPF program wrote constant zero */
	};

	#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */

	struct bpf_stack_state {
	struct bpf_reg_state spilled_ptr;
	u8 slot_type[BPF_REG_SIZE];
	};

	struct bpf_reference_state {
	/* Track each reference created with a unique id, even if the same
	* instruction creates the reference multiple times (eg, via CALL).
	*/
	int id;
	/* Instruction where the allocation of this reference occurred. This
	* is used purely to inform the user of a reference leak.
	*/
	int insn_idx;
	};

	/* state of the program:
	* type of all registers and stack info
	*/
	struct bpf_func_state {
	struct bpf_reg_state regs[MAX_BPF_REG];
	/* index of call instruction that called into this func */
	int callsite;
	/* stack frame number of this function state from pov of
	* enclosing bpf_verifier_state.
	* 0 = main function, 1 = first callee.
	*/
	u32 frameno;
	/* subprog number == index within subprog_stack_depth
	* zero == main subprog
	*/
	u32 subprogno;

	/* The following fields should be last. See copy_func_state() */
	int acquired_refs;
	struct bpf_reference_state *refs;
	int allocated_stack;
	struct bpf_stack_state *stack;
	};

	struct bpf_idx_pair {
	u32 prev_idx;
	u32 idx;
	};

	#define MAX_CALL_FRAMES 8
	struct bpf_verifier_state {
	/* call stack tracking */
	struct bpf_func_state *frame[MAX_CALL_FRAMES];
	struct bpf_verifier_state *parent;
	/*
	* 'branches' field is the number of branches left to explore:
	* 0 - all possible paths from this state reached bpf_exit or
	* were safely pruned
	* 1 - at least one path is being explored.
	* This state hasn't reached bpf_exit
	* 2 - at least two paths are being explored.
	* This state is an immediate parent of two children.
	* One is fallthrough branch with branches==1 and another
	* state is pushed into stack (to be explored later) also with
	* branches==1. The parent of this state has branches==1.
	* The verifier state tree connected via 'parent' pointer looks like:
	* 1
	* 1
	* 2 -> 1 (first 'if' pushed into stack)
	* 1
	* 2 -> 1 (second 'if' pushed into stack)
	* 1
	* 1
	* 1 bpf_exit.
	*
	* Once do_check() reaches bpf_exit, it calls update_branch_counts()
	* and the verifier state tree will look:
	* 1
	* 1
	* 2 -> 1 (first 'if' pushed into stack)
	* 1
	* 1 -> 1 (second 'if' pushed into stack)
	* 0
	* 0
	* 0 bpf_exit.
	* After pop_stack() the do_check() will resume at second 'if'.
	*
	* If is_state_visited() sees a state with branches > 0 it means
	* there is a loop. If such state is exactly equal to the current state
	* it's an infinite loop. Note states_equal() checks for states
	* equvalency, so two states being 'states_equal' does not mean
	* infinite loop. The exact comparison is provided by
	* states_maybe_looping() function. It's a stronger pre-check and
	* much faster than states_equal().
	*
	* This algorithm may not find all possible infinite loops or
	* loop iteration count may be too high.
	* In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in.
	*/
	u32 branches;
	u32 insn_idx;
	u32 curframe;
	u32 active_spin_lock;
	bool speculative;

	/* first and last insn idx of this verifier state */
	u32 first_insn_idx;
	u32 last_insn_idx;
	/* jmp history recorded from first to last.
	* backtracking is using it to go from last to first.
	* For most states jmp_history_cnt is [0-3].
	* For loops can go up to ~40.
	*/
	struct bpf_idx_pair *jmp_history;
	u32 jmp_history_cnt;
	};

	#define bpf_get_spilled_reg(slot, frame) \
	(((slot < frame->allocated_stack / BPF_REG_SIZE) && \
	(frame->stack[slot].slot_type[0] == STACK_SPILL)) \
	? &frame->stack[slot].spilled_ptr : NULL)

	/* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
	#define bpf_for_each_spilled_reg(iter, frame, reg) \
	for (iter = 0, reg = bpf_get_spilled_reg(iter, frame); \
	iter < frame->allocated_stack / BPF_REG_SIZE; \
	iter++, reg = bpf_get_spilled_reg(iter, frame))

	/* linked list of verifier states used to prune search */
	struct bpf_verifier_state_list {
	struct bpf_verifier_state state;
	struct bpf_verifier_state_list *next;
	int miss_cnt, hit_cnt;
	};

	/* Possible states for alu_state member. */
	#define BPF_ALU_SANITIZE_SRC 1U
	#define BPF_ALU_SANITIZE_DST 2U
	#define BPF_ALU_NEG_VALUE (1U << 2)
	#define BPF_ALU_NON_POINTER (1U << 3)
	#define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC \| \
	BPF_ALU_SANITIZE_DST)

	struct bpf_insn_aux_data {
	union {
	enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
	unsigned long map_state; /* pointer/poison value for maps */
	s32 call_imm; /* saved imm field of call insn */
	u32 alu_limit; /* limit for add/sub register with pointer */
	struct {
	u32 map_index; /* index into used_maps[] */
	u32 map_off; /* offset from value base address */
	};
	};
	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
	int sanitize_stack_off; /* stack slot to be cleared */
	bool seen; /* this insn was processed by the verifier */
	bool zext_dst; /* this insn zero extends dst reg */
	u8 alu_state; /* used in combination with alu_limit */
	bool prune_point;
	unsigned int orig_idx; /* original instruction index */
	};

	#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */

	#define BPF_VERIFIER_TMP_LOG_SIZE 1024

	struct bpf_verifier_log {
	u32 level;
	char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
	char __user *ubuf;
	u32 len_used;
	u32 len_total;
	};

	static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log)
	{
	return log->len_used >= log->len_total - 1;
	}

	#define BPF_LOG_LEVEL1 1
	#define BPF_LOG_LEVEL2 2
	#define BPF_LOG_STATS 4
	#define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 \| BPF_LOG_LEVEL2)
	#define BPF_LOG_MASK (BPF_LOG_LEVEL \| BPF_LOG_STATS)

	static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
	{
	return log->level && log->ubuf && !bpf_verifier_log_full(log);
	}

	#define BPF_MAX_SUBPROGS 256

	struct bpf_subprog_info {
	u32 start; /* insn idx of function entry point */
	u32 linfo_idx; /* The idx to the main_prog->aux->linfo */
	u16 stack_depth; /* max. stack depth used by this function */
	bool has_tail_call;
	};

	/* single container for all structs
	* one verifier_env per bpf_check() call
	*/
	struct bpf_verifier_env {
	u32 insn_idx;
	u32 prev_insn_idx;
	struct bpf_prog prog; / eBPF program being verified */
	const struct bpf_verifier_ops *ops;
	struct bpf_verifier_stack_elem head; / stack of verifier states to be processed */
	int stack_size; /* number of states to be processed */
	bool strict_alignment; /* perform strict pointer alignment checks */
	bool test_state_freq; /* test verifier with different pruning frequency */
	struct bpf_verifier_state cur_state; / current verifier state */
	struct bpf_verifier_state_list *explored_states; / search pruning optimization */
	struct bpf_verifier_state_list *free_list;
	struct bpf_map used_maps[MAX_USED_MAPS]; / array of map's used by eBPF program */
	u32 used_map_cnt; /* number of used maps */
	u32 id_gen; /* used to generate unique reg IDs */
	bool allow_ptr_leaks;
	bool seen_direct_write;
	struct bpf_insn_aux_data insn_aux_data; / array of per-insn state */
	const struct bpf_line_info *prev_linfo;
	struct bpf_verifier_log log;
	struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
	struct {
	int *insn_state;
	int *insn_stack;
	int cur_stack;
	} cfg;
	u32 subprog_cnt;
	/* number of instructions analyzed by the verifier */
	u32 prev_insn_processed, insn_processed;
	/* number of jmps, calls, exits analyzed so far */
	u32 prev_jmps_processed, jmps_processed;
	/* total verification time */
	u64 verification_time;
	/* maximum number of verifier states kept in 'branching' instructions */
	u32 max_states_per_insn;
	/* total number of allocated verifier states */
	u32 total_states;
	/* some states are freed during program analysis.
	* this is peak number of states. this number dominates kernel
	* memory consumption during verification
	*/
	u32 peak_states;
	/* longest register parentage chain walked for liveness marking */
	u32 longest_mark_read_walk;
	};

	__printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
	const char *fmt, va_list args);
	__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
	const char *fmt, ...);

	static inline struct bpf_func_state cur_func(struct bpf_verifier_env env)
	{
	struct bpf_verifier_state *cur = env->cur_state;

	return cur->frame[cur->curframe];
	}

	static inline struct bpf_reg_state cur_regs(struct bpf_verifier_env env)
	{
	return cur_func(env)->regs;
	}

	int bpf_prog_offload_verifier_prep(struct bpf_prog *prog);
	int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
	int insn_idx, int prev_insn_idx);
	int bpf_prog_offload_finalize(struct bpf_verifier_env *env);
	void
	bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
	struct bpf_insn *insn);
	void
	bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);

	#endif /* _LINUX_BPF_VERIFIER_H */