/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/stringify.h>
#include <linux/bsearch.h>
#include <linux/sort.h>

#include "disasm.h"

static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name) \
	[_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
};

/* bpf_check() is a static code analyzer that walks eBPF program
 * instruction by instruction and updates register/stack state.
 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
 *
 * The first pass is depth-first-search to check that the program is a DAG.
 * It rejects the following programs:
 * - larger than BPF_MAXINSNS insns
 * - if loop is present (detected via back-edge)
 * - unreachable insns exist (shouldn't be a forest. program = one function)
 * - out of bounds or malformed jumps
 * The second pass is all possible path descent from the 1st insn.
 * Since it's analyzing all pathes through the program, the length of the
 * analysis is limited to 64k insn, which may be hit even if total number of
 * insn is less then 4K, but there are too many branches that change stack/regs.
 * Number of 'branches to be analyzed' is limited to 1k
 *
 * On entry to each instruction, each register has a type, and the instruction
 * changes the types of the registers depending on instruction semantics.
 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
 * copied to R1.
 *
 * All registers are 64-bit.
 * R0 - return register
 * R1-R5 argument passing registers
 * R6-R9 callee saved registers
 * R10 - frame pointer read-only
 *
 * At the start of BPF program the register R1 contains a pointer to bpf_context
 * and has type PTR_TO_CTX.
 *
 * Verifier tracks arithmetic operations on pointers in case:
 *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
 * 1st insn copies R10 (which has FRAME_PTR) type into R1
 * and 2nd arithmetic instruction is pattern matched to recognize
 * that it wants to construct a pointer to some element within stack.
 * So after 2nd insn, the register R1 has type PTR_TO_STACK
 * (and -20 constant is saved for further stack bounds checking).
 * Meaning that this reg is a pointer to stack plus known immediate constant.
 *
 * Most of the time the registers have SCALAR_VALUE type, which
 * means the register has some value, but it's not a valid pointer.
 * (like pointer plus pointer becomes SCALAR_VALUE type)
 *
 * When verifier sees load or store instructions the type of base register
 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer
 * types recognized by check_mem_access() function.
 *
 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
 * and the range of [ptr, ptr + map's value_size) is accessible.
 *
 * registers used to pass values to function calls are checked against
 * function argument constraints.
 *
 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
 * It means that the register type passed to this function must be
 * PTR_TO_STACK and it will be used inside the function as
 * 'pointer to map element key'
 *
 * For example the argument constraints for bpf_map_lookup_elem():
 *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
 *   .arg1_type = ARG_CONST_MAP_PTR,
 *   .arg2_type = ARG_PTR_TO_MAP_KEY,
 *
 * ret_type says that this function returns 'pointer to map elem value or null'
 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
 * 2nd argument should be a pointer to stack, which will be used inside
 * the helper function as a pointer to map element key.
 *
 * On the kernel side the helper function looks like:
 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 * {
 *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 *    void *key = (void *) (unsigned long) r2;
 *    void *value;
 *
 *    here kernel can access 'key' and 'map' pointers safely, knowing that
 *    [key, key + map->key_size) bytes are valid and were initialized on
 *    the stack of eBPF program.
 * }
 *
 * Corresponding eBPF program may look like:
 *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
 *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
 *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 * here verifier looks at prototype of map_lookup_elem() and sees:
 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
 *
 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
 * and were initialized prior to this call.
 * If it's ok, then verifier allows this BPF_CALL insn and looks at
 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
 * returns ether pointer to map value or NULL.
 *
 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
 * insn, the register holding that pointer in the true branch changes state to
 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
 * branch. See check_cond_jmp_op().
 *
 * After the call R0 is set to return type of the function and registers R1-R5
 * are set to NOT_INIT to indicate that they are no longer readable.
 */

/* verifier_state + insn_idx are pushed to stack when branch is encountered */
struct bpf_verifier_stack_elem {
	/* verifer state is 'st'
	 * before processing instruction 'insn_idx'
	 * and after processing instruction 'prev_insn_idx'
	 */
	struct bpf_verifier_state st;
	int insn_idx;
	int prev_insn_idx;
	struct bpf_verifier_stack_elem *next;
};

#define BPF_COMPLEXITY_LIMIT_INSNS	131072
#define BPF_COMPLEXITY_LIMIT_STACK	1024

#define BPF_MAP_PTR_UNPRIV	1UL
#define BPF_MAP_PTR_POISON	((void *)((0xeB9FUL << 1) +	\
					  POISON_POINTER_DELTA))
#define BPF_MAP_PTR(X)		((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))

static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
{
	return BPF_MAP_PTR(aux->map_state) == BPF_MAP_PTR_POISON;
}

static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
{
	return aux->map_state & BPF_MAP_PTR_UNPRIV;
}

static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
			      const struct bpf_map *map, bool unpriv)
{
	BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
	unpriv |= bpf_map_ptr_unpriv(aux);
	aux->map_state = (unsigned long)map |
			 (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
}

struct bpf_call_arg_meta {
	struct bpf_map *map_ptr;
	bool raw_mode;
	bool pkt_access;
	int regno;
	int access_size;
};

static DEFINE_MUTEX(bpf_verifier_lock);

void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
		       va_list args)
{
	unsigned int n;

	n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);

	WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
		  "verifier log line truncated - local buffer too short\n");

	n = min(log->len_total - log->len_used - 1, n);
	log->kbuf[n] = '\0';

	if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
		log->len_used += n;
	else
		log->ubuf = NULL;
}

/* log_level controls verbosity level of eBPF verifier.
 * bpf_verifier_log_write() is used to dump the verification trace to the log,
 * so the user can figure out what's wrong with the program
 */
__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
					   const char *fmt, ...)
{
	va_list args;

	if (!bpf_verifier_log_needed(&env->log))
		return;

	va_start(args, fmt);
	bpf_verifier_vlog(&env->log, fmt, args);
	va_end(args);
}
EXPORT_SYMBOL_GPL(bpf_verifier_log_write);

__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
	struct bpf_verifier_env *env = private_data;
	va_list args;

	if (!bpf_verifier_log_needed(&env->log))
		return;

	va_start(args, fmt);
	bpf_verifier_vlog(&env->log, fmt, args);
	va_end(args);
}

static bool type_is_pkt_pointer(enum bpf_reg_type type)
{
	return type == PTR_TO_PACKET ||
	       type == PTR_TO_PACKET_META;
}

/* string representation of 'enum bpf_reg_type' */
static const char * const reg_type_str[] = {
	[NOT_INIT]		= "?",
	[SCALAR_VALUE]		= "inv",
	[PTR_TO_CTX]		= "ctx",
	[CONST_PTR_TO_MAP]	= "map_ptr",
	[PTR_TO_MAP_VALUE]	= "map_value",
	[PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
	[PTR_TO_STACK]		= "fp",
	[PTR_TO_PACKET]		= "pkt",
	[PTR_TO_PACKET_META]	= "pkt_meta",
	[PTR_TO_PACKET_END]	= "pkt_end",
};

static void print_liveness(struct bpf_verifier_env *env,
			   enum bpf_reg_liveness live)
{
	if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN))
	    verbose(env, "_");
	if (live & REG_LIVE_READ)
		verbose(env, "r");
	if (live & REG_LIVE_WRITTEN)
		verbose(env, "w");
}

static struct bpf_func_state *func(struct bpf_verifier_env *env,
				   const struct bpf_reg_state *reg)
{
	struct bpf_verifier_state *cur = env->cur_state;

	return cur->frame[reg->frameno];
}

static void print_verifier_state(struct bpf_verifier_env *env,
				 const struct bpf_func_state *state)
{
	const struct bpf_reg_state *reg;
	enum bpf_reg_type t;
	int i;

	if (state->frameno)
		verbose(env, " frame%d:", state->frameno);
	for (i = 0; i < MAX_BPF_REG; i++) {
		reg = &state->regs[i];
		t = reg->type;
		if (t == NOT_INIT)
			continue;
		verbose(env, " R%d", i);
		print_liveness(env, reg->live);
		verbose(env, "=%s", reg_type_str[t]);
		if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
		    tnum_is_const(reg->var_off)) {
			/* reg->off should be 0 for SCALAR_VALUE */
			verbose(env, "%lld", reg->var_off.value + reg->off);
			if (t == PTR_TO_STACK)
				verbose(env, ",call_%d", func(env, reg)->callsite);
		} else {
			verbose(env, "(id=%d", reg->id);
			if (t != SCALAR_VALUE)
				verbose(env, ",off=%d", reg->off);
			if (type_is_pkt_pointer(t))
				verbose(env, ",r=%d", reg->range);
			else if (t == CONST_PTR_TO_MAP ||
				 t == PTR_TO_MAP_VALUE ||
				 t == PTR_TO_MAP_VALUE_OR_NULL)
				verbose(env, ",ks=%d,vs=%d",
					reg->map_ptr->key_size,
					reg->map_ptr->value_size);
			if (tnum_is_const(reg->var_off)) {
				/* Typically an immediate SCALAR_VALUE, but
				 * could be a pointer whose offset is too big
				 * for reg->off
				 */
				verbose(env, ",imm=%llx", reg->var_off.value);
			} else {
				if (reg->smin_value != reg->umin_value &&
				    reg->smin_value != S64_MIN)
					verbose(env, ",smin_value=%lld",
						(long long)reg->smin_value);
				if (reg->smax_value != reg->umax_value &&
				    reg->smax_value != S64_MAX)
					verbose(env, ",smax_value=%lld",
						(long long)reg->smax_value);
				if (reg->umin_value != 0)
					verbose(env, ",umin_value=%llu",
						(unsigned long long)reg->umin_value);
				if (reg->umax_value != U64_MAX)
					verbose(env, ",umax_value=%llu",
						(unsigned long long)reg->umax_value);
				if (!tnum_is_unknown(reg->var_off)) {
					char tn_buf[48];

					tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
					verbose(env, ",var_off=%s", tn_buf);
				}
			}
			verbose(env, ")");
		}
	}
	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
		if (state->stack[i].slot_type[0] == STACK_SPILL) {
			verbose(env, " fp%d",
				(-i - 1) * BPF_REG_SIZE);
			print_liveness(env, state->stack[i].spilled_ptr.live);
			verbose(env, "=%s",
				reg_type_str[state->stack[i].spilled_ptr.type]);
		}
		if (state->stack[i].slot_type[0] == STACK_ZERO)
			verbose(env, " fp%d=0", (-i - 1) * BPF_REG_SIZE);
	}
	verbose(env, "\n");
}

static int copy_stack_state(struct bpf_func_state *dst,
			    const struct bpf_func_state *src)
{
	if (!src->stack)
		return 0;
	if (WARN_ON_ONCE(dst->allocated_stack < src->allocated_stack)) {
		/* internal bug, make state invalid to reject the program */
		memset(dst, 0, sizeof(*dst));
		return -EFAULT;
	}
	memcpy(dst->stack, src->stack,
	       sizeof(*src->stack) * (src->allocated_stack / BPF_REG_SIZE));
	return 0;
}

/* do_check() starts with zero-sized stack in struct bpf_verifier_state to
 * make it consume minimal amount of memory. check_stack_write() access from
 * the program calls into realloc_func_state() to grow the stack size.
 * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
 * which this function copies over. It points to previous bpf_verifier_state
 * which is never reallocated
 */
static int realloc_func_state(struct bpf_func_state *state, int size,
			      bool copy_old)
{
	u32 old_size = state->allocated_stack;
	struct bpf_stack_state *new_stack;
	int slot = size / BPF_REG_SIZE;

	if (size <= old_size || !size) {
		if (copy_old)
			return 0;
		state->allocated_stack = slot * BPF_REG_SIZE;
		if (!size && old_size) {
			kfree(state->stack);
			state->stack = NULL;
		}
		return 0;
	}
	new_stack = kmalloc_array(slot, sizeof(struct bpf_stack_state),
				  GFP_KERNEL);
	if (!new_stack)
		return -ENOMEM;
	if (copy_old) {
		if (state->stack)
			memcpy(new_stack, state->stack,
			       sizeof(*new_stack) * (old_size / BPF_REG_SIZE));
		memset(new_stack + old_size / BPF_REG_SIZE, 0,
		       sizeof(*new_stack) * (size - old_size) / BPF_REG_SIZE);
	}
	state->allocated_stack = slot * BPF_REG_SIZE;
	kfree(state->stack);
	state->stack = new_stack;
	return 0;
}

static void free_func_state(struct bpf_func_state *state)
{
	if (!state)
		return;
	kfree(state->stack);
	kfree(state);
}

static void free_verifier_state(struct bpf_verifier_state *state,
				bool free_self)
{
	int i;

	for (i = 0; i <= state->curframe; i++) {
		free_func_state(state->frame[i]);
		state->frame[i] = NULL;
	}
	if (free_self)
		kfree(state);
}

/* copy verifier state from src to dst growing dst stack space
 * when necessary to accommodate larger src stack
 */
static int copy_func_state(struct bpf_func_state *dst,
			   const struct bpf_func_state *src)
{
	int err;

	err = realloc_func_state(dst, src->allocated_stack, false);
	if (err)
		return err;
	memcpy(dst, src, offsetof(struct bpf_func_state, allocated_stack));
	return copy_stack_state(dst, src);
}

static int copy_verifier_state(struct bpf_verifier_state *dst_state,
			       const struct bpf_verifier_state *src)
{
	struct bpf_func_state *dst;
	int i, err;

	/* if dst has more stack frames then src frame, free them */
	for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
		free_func_state(dst_state->frame[i]);
		dst_state->frame[i] = NULL;
	}
	dst_state->curframe = src->curframe;
	dst_state->parent = src->parent;
	for (i = 0; i <= src->curframe; i++) {
		dst = dst_state->frame[i];
		if (!dst) {
			dst = kzalloc(sizeof(*dst), GFP_KERNEL);
			if (!dst)
				return -ENOMEM;
			dst_state->frame[i] = dst;
		}
		err = copy_func_state(dst, src->frame[i]);
		if (err)
			return err;
	}
	return 0;
}

static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
		     int *insn_idx)
{
	struct bpf_verifier_state *cur = env->cur_state;
	struct bpf_verifier_stack_elem *elem, *head = env->head;
	int err;

	if (env->head == NULL)
		return -ENOENT;

	if (cur) {
		err = copy_verifier_state(cur, &head->st);
		if (err)
			return err;
	}
	if (insn_idx)
		*insn_idx = head->insn_idx;
	if (prev_insn_idx)
		*prev_insn_idx = head->prev_insn_idx;
	elem = head->next;
	free_verifier_state(&head->st, false);
	kfree(head);
	env->head = elem;
	env->stack_size--;
	return 0;
}

static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
					     int insn_idx, int prev_insn_idx)
{
	struct bpf_verifier_state *cur = env->cur_state;
	struct bpf_verifier_stack_elem *elem;
	int err;

	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
	if (!elem)
		goto err;

	elem->insn_idx = insn_idx;
	elem->prev_insn_idx = prev_insn_idx;
	elem->next = env->head;
	env->head = elem;
	env->stack_size++;
	err = copy_verifier_state(&elem->st, cur);
	if (err)
		goto err;
	if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
		verbose(env, "BPF program is too complex\n");
		goto err;
	}
	return &elem->st;
err:
	free_verifier_state(env->cur_state, true);
	env->cur_state = NULL;
	/* pop all elements and return */
	while (!pop_stack(env, NULL, NULL));
	return NULL;
}

#define CALLER_SAVED_REGS 6
static const int caller_saved[CALLER_SAVED_REGS] = {
	BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
};

static void __mark_reg_not_init(struct bpf_reg_state *reg);

/* Mark the unknown part of a register (variable offset or scalar value) as
 * known to have the value @imm.
 */
static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
	reg->id = 0;
	reg->var_off = tnum_const(imm);
	reg->smin_value = (s64)imm;
	reg->smax_value = (s64)imm;
	reg->umin_value = imm;
	reg->umax_value = imm;
}

/* Mark the 'variable offset' part of a register as zero.  This should be
 * used only on registers holding a pointer type.
 */
static void __mark_reg_known_zero(struct bpf_reg_state *reg)
{
	__mark_reg_known(reg, 0);
}

static void __mark_reg_const_zero(struct bpf_reg_state *reg)
{
	__mark_reg_known(reg, 0);
	reg->off = 0;
	reg->type = SCALAR_VALUE;
}

static void mark_reg_known_zero(struct bpf_verifier_env *env,
				struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs */
		for (regno = 0; regno < MAX_BPF_REG; regno++)
			__mark_reg_not_init(regs + regno);
		return;
	}
	__mark_reg_known_zero(regs + regno);
}

static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
{
	return type_is_pkt_pointer(reg->type);
}

static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
{
	return reg_is_pkt_pointer(reg) ||
	       reg->type == PTR_TO_PACKET_END;
}

/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
				    enum bpf_reg_type which)
{
	/* The register can already have a range from prior markings.
	 * This is fine as long as it hasn't been advanced from its
	 * origin.
	 */
	return reg->type == which &&
	       reg->id == 0 &&
	       reg->off == 0 &&
	       tnum_equals_const(reg->var_off, 0);
}

/* Attempts to improve min/max values based on var_off information */
static void __update_reg_bounds(struct bpf_reg_state *reg)
{
	/* min signed is max(sign bit) | min(other bits) */
	reg->smin_value = max_t(s64, reg->smin_value,
				reg->var_off.value | (reg->var_off.mask & S64_MIN));
	/* max signed is min(sign bit) | max(other bits) */
	reg->smax_value = min_t(s64, reg->smax_value,
				reg->var_off.value | (reg->var_off.mask & S64_MAX));
	reg->umin_value = max(reg->umin_value, reg->var_off.value);
	reg->umax_value = min(reg->umax_value,
			      reg->var_off.value | reg->var_off.mask);
}

/* Uses signed min/max values to inform unsigned, and vice-versa */
static void __reg_deduce_bounds(struct bpf_reg_state *reg)
{
	/* Learn sign from signed bounds.
	 * If we cannot cross the sign boundary, then signed and unsigned bounds
	 * are the same, so combine.  This works even in the negative case, e.g.
	 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
	 */
	if (reg->smin_value >= 0 || reg->smax_value < 0) {
		reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
							  reg->umin_value);
		reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
							  reg->umax_value);
		return;
	}
	/* Learn sign from unsigned bounds.  Signed bounds cross the sign
	 * boundary, so we must be careful.
	 */
	if ((s64)reg->umax_value >= 0) {
		/* Positive.  We can't learn anything from the smin, but smax
		 * is positive, hence safe.
		 */
		reg->smin_value = reg->umin_value;
		reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
							  reg->umax_value);
	} else if ((s64)reg->umin_value < 0) {
		/* Negative.  We can't learn anything from the smax, but smin
		 * is negative, hence safe.
		 */
		reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
							  reg->umin_value);
		reg->smax_value = reg->umax_value;
	}
}

/* Attempts to improve var_off based on unsigned min/max information */
static void __reg_bound_offset(struct bpf_reg_state *reg)
{
	reg->var_off = tnum_intersect(reg->var_off,
				      tnum_range(reg->umin_value,
						 reg->umax_value));
}

/* Reset the min/max bounds of a register */
static void __mark_reg_unbounded(struct bpf_reg_state *reg)
{
	reg->smin_value = S64_MIN;
	reg->smax_value = S64_MAX;
	reg->umin_value = 0;
	reg->umax_value = U64_MAX;
}

/* Mark a register as having a completely unknown (scalar) value. */
static void __mark_reg_unknown(struct bpf_reg_state *reg)
{
	reg->type = SCALAR_VALUE;
	reg->id = 0;
	reg->off = 0;
	reg->var_off = tnum_unknown;
	reg->frameno = 0;
	__mark_reg_unbounded(reg);
}

static void mark_reg_unknown(struct bpf_verifier_env *env,
			     struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs except FP */
		for (regno = 0; regno < BPF_REG_FP; regno++)
			__mark_reg_not_init(regs + regno);
		return;
	}
	__mark_reg_unknown(regs + regno);
}

static void __mark_reg_not_init(struct bpf_reg_state *reg)
{
	__mark_reg_unknown(reg);
	reg->type = NOT_INIT;
}

static void mark_reg_not_init(struct bpf_verifier_env *env,
			      struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs except FP */
		for (regno = 0; regno < BPF_REG_FP; regno++)
			__mark_reg_not_init(regs + regno);
		return;
	}
	__mark_reg_not_init(regs + regno);
}

static void init_reg_state(struct bpf_verifier_env *env,
			   struct bpf_func_state *state)
{
	struct bpf_reg_state *regs = state->regs;
	int i;

	for (i = 0; i < MAX_BPF_REG; i++) {
		mark_reg_not_init(env, regs, i);
		regs[i].live = REG_LIVE_NONE;
	}

	/* frame pointer */
	regs[BPF_REG_FP].type = PTR_TO_STACK;
	mark_reg_known_zero(env, regs, BPF_REG_FP);
	regs[BPF_REG_FP].frameno = state->frameno;

	/* 1st arg to a function */
	regs[BPF_REG_1].type = PTR_TO_CTX;
	mark_reg_known_zero(env, regs, BPF_REG_1);
}

#define BPF_MAIN_FUNC (-1)
static void init_func_state(struct bpf_verifier_env *env,
			    struct bpf_func_state *state,
			    int callsite, int frameno, int subprogno)
{
	state->callsite = callsite;
	state->frameno = frameno;
	state->subprogno = subprogno;
	init_reg_state(env, state);
}

enum reg_arg_type {
	SRC_OP,		/* register is used as source operand */
	DST_OP,		/* register is used as destination operand */
	DST_OP_NO_MARK	/* same as above, check only, don't mark */
};

static int cmp_subprogs(const void *a, const void *b)
{
	return *(int *)a - *(int *)b;
}

static int find_subprog(struct bpf_verifier_env *env, int off)
{
	u32 *p;

	p = bsearch(&off, env->subprog_starts, env->subprog_cnt,
		    sizeof(env->subprog_starts[0]), cmp_subprogs);
	if (!p)
		return -ENOENT;
	return p - env->subprog_starts;

}

static int add_subprog(struct bpf_verifier_env *env, int off)
{
	int insn_cnt = env->prog->len;
	int ret;

	if (off >= insn_cnt || off < 0) {
		verbose(env, "call to invalid destination\n");
		return -EINVAL;
	}
	ret = find_subprog(env, off);
	if (ret >= 0)
		return 0;
	if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
		verbose(env, "too many subprograms\n");
		return -E2BIG;
	}
	env->subprog_starts[env->subprog_cnt++] = off;
	sort(env->subprog_starts, env->subprog_cnt,
	     sizeof(env->subprog_starts[0]), cmp_subprogs, NULL);
	return 0;
}

static int check_subprogs(struct bpf_verifier_env *env)
{
	int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
	struct bpf_insn *insn = env->prog->insnsi;
	int insn_cnt = env->prog->len;

	/* determine subprog starts. The end is one before the next starts */
	for (i = 0; i < insn_cnt; i++) {
		if (insn[i].code != (BPF_JMP | BPF_CALL))
			continue;
		if (insn[i].src_reg != BPF_PSEUDO_CALL)
			continue;
		if (!env->allow_ptr_leaks) {
			verbose(env, "function calls to other bpf functions are allowed for root only\n");
			return -EPERM;
		}
		if (bpf_prog_is_dev_bound(env->prog->aux)) {
			verbose(env, "function calls in offloaded programs are not supported yet\n");
			return -EINVAL;
		}
		ret = add_subprog(env, i + insn[i].imm + 1);
		if (ret < 0)
			return ret;
	}

	if (env->log.level > 1)
		for (i = 0; i < env->subprog_cnt; i++)
			verbose(env, "func#%d @%d\n", i, env->subprog_starts[i]);

	/* now check that all jumps are within the same subprog */
	subprog_start = 0;
	if (env->subprog_cnt == cur_subprog)
		subprog_end = insn_cnt;
	else
		subprog_end = env->subprog_starts[cur_subprog++];
	for (i = 0; i < insn_cnt; i++) {
		u8 code = insn[i].code;

		if (BPF_CLASS(code) != BPF_JMP)
			goto next;
		if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
			goto next;
		off = i + insn[i].off + 1;
		if (off < subprog_start || off >= subprog_end) {
			verbose(env, "jump out of range from insn %d to %d\n", i, off);
			return -EINVAL;
		}
next:
		if (i == subprog_end - 1) {
			/* to avoid fall-through from one subprog into another
			 * the last insn of the subprog should be either exit
			 * or unconditional jump back
			 */
			if (code != (BPF_JMP | BPF_EXIT) &&
			    code != (BPF_JMP | BPF_JA)) {
				verbose(env, "last insn is not an exit or jmp\n");
				return -EINVAL;
			}
			subprog_start = subprog_end;
			if (env->subprog_cnt == cur_subprog)
				subprog_end = insn_cnt;
			else
				subprog_end = env->subprog_starts[cur_subprog++];
		}
	}
	return 0;
}

static
struct bpf_verifier_state *skip_callee(struct bpf_verifier_env *env,
				       const struct bpf_verifier_state *state,
				       struct bpf_verifier_state *parent,
				       u32 regno)
{
	struct bpf_verifier_state *tmp = NULL;

	/* 'parent' could be a state of caller and
	 * 'state' could be a state of callee. In such case
	 * parent->curframe < state->curframe
	 * and it's ok for r1 - r5 registers
	 *
	 * 'parent' could be a callee's state after it bpf_exit-ed.
	 * In such case parent->curframe > state->curframe
	 * and it's ok for r0 only
	 */
	if (parent->curframe == state->curframe ||
	    (parent->curframe < state->curframe &&
	     regno >= BPF_REG_1 && regno <= BPF_REG_5) ||
	    (parent->curframe > state->curframe &&
	       regno == BPF_REG_0))
		return parent;

	if (parent->curframe > state->curframe &&
	    regno >= BPF_REG_6) {
		/* for callee saved regs we have to skip the whole chain
		 * of states that belong to callee and mark as LIVE_READ
		 * the registers before the call
		 */
		tmp = parent;
		while (tmp && tmp->curframe != state->curframe) {
			tmp = tmp->parent;
		}
		if (!tmp)
			goto bug;
		parent = tmp;
	} else {
		goto bug;
	}
	return parent;
bug:
	verbose(env, "verifier bug regno %d tmp %p\n", regno, tmp);
	verbose(env, "regno %d parent frame %d current frame %d\n",
		regno, parent->curframe, state->curframe);
	return NULL;
}

static int mark_reg_read(struct bpf_verifier_env *env,
			 const struct bpf_verifier_state *state,
			 struct bpf_verifier_state *parent,
			 u32 regno)
{
	bool writes = parent == state->parent; /* Observe write marks */

	if (regno == BPF_REG_FP)
		/* We don't need to worry about FP liveness because it's read-only */
		return 0;

	while (parent) {
		/* if read wasn't screened by an earlier write ... */
		if (writes && state->frame[state->curframe]->regs[regno].live & REG_LIVE_WRITTEN)
			break;
		parent = skip_callee(env, state, parent, regno);
		if (!parent)
			return -EFAULT;
		/* ... then we depend on parent's value */
		parent->frame[parent->curframe]->regs[regno].live |= REG_LIVE_READ;
		state = parent;
		parent = state->parent;
		writes = true;
	}
	return 0;
}

static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
			 enum reg_arg_type t)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *regs = state->regs;

	if (regno >= MAX_BPF_REG) {
		verbose(env, "R%d is invalid\n", regno);
		return -EINVAL;
	}

	if (t == SRC_OP) {
		/* check whether register used as source operand can be read */
		if (regs[regno].type == NOT_INIT) {
			verbose(env, "R%d !read_ok\n", regno);
			return -EACCES;
		}
		return mark_reg_read(env, vstate, vstate->parent, regno);
	} else {
		/* check whether register used as dest operand can be written to */
		if (regno == BPF_REG_FP) {
			verbose(env, "frame pointer is read only\n");
			return -EACCES;
		}
		regs[regno].live |= REG_LIVE_WRITTEN;
		if (t == DST_OP)
			mark_reg_unknown(env, regs, regno);
	}
	return 0;
}

static bool is_spillable_regtype(enum bpf_reg_type type)
{
	switch (type) {
	case PTR_TO_MAP_VALUE:
	case PTR_TO_MAP_VALUE_OR_NULL:
	case PTR_TO_STACK:
	case PTR_TO_CTX:
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
	case PTR_TO_PACKET_END:
	case CONST_PTR_TO_MAP:
		return true;
	default:
		return false;
	}
}

/* Does this register contain a constant zero? */
static bool register_is_null(struct bpf_reg_state *reg)
{
	return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}

/* check_stack_read/write functions track spill/fill of registers,
 * stack boundary and alignment are checked in check_mem_access()
 */
static int check_stack_write(struct bpf_verifier_env *env,
			     struct bpf_func_state *state, /* func where register points to */
			     int off, int size, int value_regno, int insn_idx)
{
	struct bpf_func_state *cur; /* state of the current function */
	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
	enum bpf_reg_type type;

	err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
				 true);
	if (err)
		return err;
	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
	 * so it's aligned access and [off, off + size) are within stack limits
	 */
	if (!env->allow_ptr_leaks &&
	    state->stack[spi].slot_type[0] == STACK_SPILL &&
	    size != BPF_REG_SIZE) {
		verbose(env, "attempt to corrupt spilled pointer on stack\n");
		return -EACCES;
	}

	cur = env->cur_state->frame[env->cur_state->curframe];
	if (value_regno >= 0 &&
	    is_spillable_regtype((type = cur->regs[value_regno].type))) {

		/* register containing pointer is being spilled into stack */
		if (size != BPF_REG_SIZE) {
			verbose(env, "invalid size of register spill\n");
			return -EACCES;
		}

		if (state != cur && type == PTR_TO_STACK) {
			verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
			return -EINVAL;
		}

		/* save register state */
		state->stack[spi].spilled_ptr = cur->regs[value_regno];
		state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;

		for (i = 0; i < BPF_REG_SIZE; i++) {
			if (state->stack[spi].slot_type[i] == STACK_MISC &&
			    !env->allow_ptr_leaks) {
				int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
				int soff = (-spi - 1) * BPF_REG_SIZE;

				/* detected reuse of integer stack slot with a pointer
				 * which means either llvm is reusing stack slot or
				 * an attacker is trying to exploit CVE-2018-3639
				 * (speculative store bypass)
				 * Have to sanitize that slot with preemptive
				 * store of zero.
				 */
				if (*poff && *poff != soff) {
					/* disallow programs where single insn stores
					 * into two different stack slots, since verifier
					 * cannot sanitize them
					 */
					verbose(env,
						"insn %d cannot access two stack slots fp%d and fp%d",
						insn_idx, *poff, soff);
					return -EINVAL;
				}
				*poff = soff;
			}
			state->stack[spi].slot_type[i] = STACK_SPILL;
		}
	} else {
		u8 type = STACK_MISC;

		/* regular write of data into stack */
		state->stack[spi].spilled_ptr = (struct bpf_reg_state) {};

		/* only mark the slot as written if all 8 bytes were written
		 * otherwise read propagation may incorrectly stop too soon
		 * when stack slots are partially written.
		 * This heuristic means that read propagation will be
		 * conservative, since it will add reg_live_read marks
		 * to stack slots all the way to first state when programs
		 * writes+reads less than 8 bytes
		 */
		if (size == BPF_REG_SIZE)
			state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;

		/* when we zero initialize stack slots mark them as such */
		if (value_regno >= 0 &&
		    register_is_null(&cur->regs[value_regno]))
			type = STACK_ZERO;

		for (i = 0; i < size; i++)
			state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
				type;
	}
	return 0;
}

/* registers of every function are unique and mark_reg_read() propagates
 * the liveness in the following cases:
 * - from callee into caller for R1 - R5 that were used as arguments
 * - from caller into callee for R0 that used as result of the call
 * - from caller to the same caller skipping states of the callee for R6 - R9,
 *   since R6 - R9 are callee saved by implicit function prologue and
 *   caller's R6 != callee's R6, so when we propagate liveness up to
 *   parent states we need to skip callee states for R6 - R9.
 *
 * stack slot marking is different, since stacks of caller and callee are
 * accessible in both (since caller can pass a pointer to caller's stack to
 * callee which can pass it to another function), hence mark_stack_slot_read()
 * has to propagate the stack liveness to all parent states at given frame number.
 * Consider code:
 * f1() {
 *   ptr = fp - 8;
 *   *ptr = ctx;
 *   call f2 {
 *      .. = *ptr;
 *   }
 *   .. = *ptr;
 * }
 * First *ptr is reading from f1's stack and mark_stack_slot_read() has
 * to mark liveness at the f1's frame and not f2's frame.
 * Second *ptr is also reading from f1's stack and mark_stack_slot_read() has
 * to propagate liveness to f2 states at f1's frame level and further into
 * f1 states at f1's frame level until write into that stack slot
 */
static void mark_stack_slot_read(struct bpf_verifier_env *env,
				 const struct bpf_verifier_state *state,
				 struct bpf_verifier_state *parent,
				 int slot, int frameno)
{
	bool writes = parent == state->parent; /* Observe write marks */

	while (parent) {
		if (parent->frame[frameno]->allocated_stack <= slot * BPF_REG_SIZE)
			/* since LIVE_WRITTEN mark is only done for full 8-byte
			 * write the read marks are conservative and parent
			 * state may not even have the stack allocated. In such case
			 * end the propagation, since the loop reached beginning
			 * of the function
			 */
			break;
		/* if read wasn't screened by an earlier write ... */
		if (writes && state->frame[frameno]->stack[slot].spilled_ptr.live & REG_LIVE_WRITTEN)
			break;
		/* ... then we depend on parent's value */
		parent->frame[frameno]->stack[slot].spilled_ptr.live |= REG_LIVE_READ;
		state = parent;
		parent = state->parent;
		writes = true;
	}
}

static int check_stack_read(struct bpf_verifier_env *env,
			    struct bpf_func_state *reg_state /* func where register points to */,
			    int off, int size, int value_regno)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
	u8 *stype;

	if (reg_state->allocated_stack <= slot) {
		verbose(env, "invalid read from stack off %d+0 size %d\n",
			off, size);
		return -EACCES;
	}
	stype = reg_state->stack[spi].slot_type;

	if (stype[0] == STACK_SPILL) {
		if (size != BPF_REG_SIZE) {
			verbose(env, "invalid size of register spill\n");
			return -EACCES;
		}
		for (i = 1; i < BPF_REG_SIZE; i++) {
			if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
				verbose(env, "corrupted spill memory\n");
				return -EACCES;
			}
		}

		if (value_regno >= 0) {
			/* restore register state from stack */
			state->regs[value_regno] = reg_state->stack[spi].spilled_ptr;
			/* mark reg as written since spilled pointer state likely
			 * has its liveness marks cleared by is_state_visited()
			 * which resets stack/reg liveness for state transitions
			 */
			state->regs[value_regno].live |= REG_LIVE_WRITTEN;
		}
		mark_stack_slot_read(env, vstate, vstate->parent, spi,
				     reg_state->frameno);
		return 0;
	} else {
		int zeros = 0;

		for (i = 0; i < size; i++) {
			if (stype[(slot - i) % BPF_REG_SIZE] == STACK_MISC)
				continue;
			if (stype[(slot - i) % BPF_REG_SIZE] == STACK_ZERO) {
				zeros++;
				continue;
			}
			verbose(env, "invalid read from stack off %d+%d size %d\n",
				off, i, size);
			return -EACCES;
		}
		mark_stack_slot_read(env, vstate, vstate->parent, spi,
				     reg_state->frameno);
		if (value_regno >= 0) {
			if (zeros == size) {
				/* any size read into register is zero extended,
				 * so the whole register == const_zero
				 */
				__mark_reg_const_zero(&state->regs[value_regno]);
			} else {
				/* have read misc data from the stack */
				mark_reg_unknown(env, state->regs, value_regno);
			}
			state->regs[value_regno].live |= REG_LIVE_WRITTEN;
		}
		return 0;
	}
}

/* check read/write into map element returned by bpf_map_lookup_elem() */
static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
			      int size, bool zero_size_allowed)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_map *map = regs[regno].map_ptr;

	if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
	    off + size > map->value_size) {
		verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
			map->value_size, off, size);
		return -EACCES;
	}
	return 0;
}

/* check read/write into a map element with possible variable offset */
static int check_map_access(struct bpf_verifier_env *env, u32 regno,
			    int off, int size, bool zero_size_allowed)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *reg = &state->regs[regno];
	int err;

	/* We may have adjusted the register to this map value, so we
	 * need to try adding each of min_value and max_value to off
	 * to make sure our theoretical access will be safe.
	 */
	if (env->log.level)
		print_verifier_state(env, state);
	/* The minimum value is only important with signed
	 * comparisons where we can't assume the floor of a
	 * value is 0.  If we are using signed variables for our
	 * index'es we need to make sure that whatever we use
	 * will have a set floor within our range.
	 */
	if (reg->smin_value < 0) {
		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
			regno);
		return -EACCES;
	}
	err = __check_map_access(env, regno, reg->smin_value + off, size,
				 zero_size_allowed);
	if (err) {
		verbose(env, "R%d min value is outside of the array range\n",
			regno);
		return err;
	}

	/* If we haven't set a max value then we need to bail since we can't be
	 * sure we won't do bad things.
	 * If reg->umax_value + off could overflow, treat that as unbounded too.
	 */
	if (reg->umax_value >= BPF_MAX_VAR_OFF) {
		verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n",
			regno);
		return -EACCES;
	}
	err = __check_map_access(env, regno, reg->umax_value + off, size,
				 zero_size_allowed);
	if (err)
		verbose(env, "R%d max value is outside of the array range\n",
			regno);
	return err;
}

#define MAX_PACKET_OFF 0xffff

static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
				       const struct bpf_call_arg_meta *meta,
				       enum bpf_access_type t)
{
	switch (env->prog->type) {
	case BPF_PROG_TYPE_LWT_IN:
	case BPF_PROG_TYPE_LWT_OUT:
		/* dst_input() and dst_output() can't write for now */
		if (t == BPF_WRITE)
			return false;
		/* fallthrough */
	case BPF_PROG_TYPE_SCHED_CLS:
	case BPF_PROG_TYPE_SCHED_ACT:
	case BPF_PROG_TYPE_XDP:
	case BPF_PROG_TYPE_LWT_XMIT:
	case BPF_PROG_TYPE_SK_SKB:
	case BPF_PROG_TYPE_SK_MSG:
		if (meta)
			return meta->pkt_access;

		env->seen_direct_write = true;
		return true;
	default:
		return false;
	}
}

static int __check_packet_access(struct bpf_verifier_env *env, u32 regno,
				 int off, int size, bool zero_size_allowed)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[regno];

	if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
	    (u64)off + size > reg->range) {
		verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
			off, size, regno, reg->id, reg->off, reg->range);
		return -EACCES;
	}
	return 0;
}

static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
			       int size, bool zero_size_allowed)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[regno];
	int err;

	/* We may have added a variable offset to the packet pointer; but any
	 * reg->range we have comes after that.  We are only checking the fixed
	 * offset.
	 */

	/* We don't allow negative numbers, because we aren't tracking enough
	 * detail to prove they're safe.
	 */
	if (reg->smin_value < 0) {
		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
			regno);
		return -EACCES;
	}
	err = __check_packet_access(env, regno, off, size, zero_size_allowed);
	if (err) {
		verbose(env, "R%d offset is outside of the packet\n", regno);
		return err;
	}
	return err;
}

/* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
			    enum bpf_access_type t, enum bpf_reg_type *reg_type)
{
	struct bpf_insn_access_aux info = {
		.reg_type = *reg_type,
	};

	if (env->ops->is_valid_access &&
	    env->ops->is_valid_access(off, size, t, env->prog, &info)) {
		/* A non zero info.ctx_field_size indicates that this field is a
		 * candidate for later verifier transformation to load the whole
		 * field and then apply a mask when accessed with a narrower
		 * access than actual ctx access size. A zero info.ctx_field_size
		 * will only allow for whole field access and rejects any other
		 * type of narrower access.
		 */
		*reg_type = info.reg_type;

		env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
		/* remember the offset of last byte accessed in ctx */
		if (env->prog->aux->max_ctx_offset < off + size)
			env->prog->aux->max_ctx_offset = off + size;
		return 0;
	}

	verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
	return -EACCES;
}

static bool __is_pointer_value(bool allow_ptr_leaks,
			       const struct bpf_reg_state *reg)
{
	if (allow_ptr_leaks)
		return false;

	return reg->type != SCALAR_VALUE;
}

static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
{
	return __is_pointer_value(env->allow_ptr_leaks, cur_regs(env) + regno);
}

static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = cur_regs(env) + regno;

	return reg->type == PTR_TO_CTX;
}

static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = cur_regs(env) + regno;

	return type_is_pkt_pointer(reg->type);
}

static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
				   const struct bpf_reg_state *reg,
				   int off, int size, bool strict)
{
	struct tnum reg_off;
	int ip_align;

	/* Byte size accesses are always allowed. */
	if (!strict || size == 1)
		return 0;

	/* For platforms that do not have a Kconfig enabling
	 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
	 * NET_IP_ALIGN is universally set to '2'.  And on platforms
	 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
	 * to this code only in strict mode where we want to emulate
	 * the NET_IP_ALIGN==2 checking.  Therefore use an
	 * unconditional IP align value of '2'.
	 */
	ip_align = 2;

	reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
	if (!tnum_is_aligned(reg_off, size)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env,
			"misaligned packet access off %d+%s+%d+%d size %d\n",
			ip_align, tn_buf, reg->off, off, size);
		return -EACCES;
	}

	return 0;
}

static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
				       const struct bpf_reg_state *reg,
				       const char *pointer_desc,
				       int off, int size, bool strict)
{
	struct tnum reg_off;

	/* Byte size accesses are always allowed. */
	if (!strict || size == 1)
		return 0;

	reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
	if (!tnum_is_aligned(reg_off, size)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
			pointer_desc, tn_buf, reg->off, off, size);
		return -EACCES;
	}

	return 0;
}

static int check_ptr_alignment(struct bpf_verifier_env *env,
			       const struct bpf_reg_state *reg, int off,
			       int size, bool strict_alignment_once)
{
	bool strict = env->strict_alignment || strict_alignment_once;
	const char *pointer_desc = "";

	switch (reg->type) {
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
		/* Special case, because of NET_IP_ALIGN. Given metadata sits
		 * right in front, treat it the very same way.
		 */
		return check_pkt_ptr_alignment(env, reg, off, size, strict);
	case PTR_TO_MAP_VALUE:
		pointer_desc = "value ";
		break;
	case PTR_TO_CTX:
		pointer_desc = "context ";
		break;
	case PTR_TO_STACK:
		pointer_desc = "stack ";
		/* The stack spill tracking logic in check_stack_write()
		 * and check_stack_read() relies on stack accesses being
		 * aligned.
		 */
		strict = true;
		break;
	default:
		break;
	}
	return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
					   strict);
}

static int update_stack_depth(struct bpf_verifier_env *env,
			      const struct bpf_func_state *func,
			      int off)
{
	u16 stack = env->subprog_stack_depth[func->subprogno];

	if (stack >= -off)
		return 0;

	/* update known max for given subprogram */
	env->subprog_stack_depth[func->subprogno] = -off;
	return 0;
}

/* starting from main bpf function walk all instructions of the function
 * and recursively walk all callees that given function can call.
 * Ignore jump and exit insns.
 * Since recursion is prevented by check_cfg() this algorithm
 * only needs a local stack of MAX_CALL_FRAMES to remember callsites
 */
static int check_max_stack_depth(struct bpf_verifier_env *env)
{
	int depth = 0, frame = 0, subprog = 0, i = 0, subprog_end;
	struct bpf_insn *insn = env->prog->insnsi;
	int insn_cnt = env->prog->len;
	int ret_insn[MAX_CALL_FRAMES];
	int ret_prog[MAX_CALL_FRAMES];

process_func:
	/* round up to 32-bytes, since this is granularity
	 * of interpreter stack size
	 */
	depth += round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
	if (depth > MAX_BPF_STACK) {
		verbose(env, "combined stack size of %d calls is %d. Too large\n",
			frame + 1, depth);
		return -EACCES;
	}
continue_func:
	if (env->subprog_cnt == subprog)
		subprog_end = insn_cnt;
	else
		subprog_end = env->subprog_starts[subprog];
	for (; i < subprog_end; i++) {
		if (insn[i].code != (BPF_JMP | BPF_CALL))
			continue;
		if (insn[i].src_reg != BPF_PSEUDO_CALL)
			continue;
		/* remember insn and function to return to */
		ret_insn[frame] = i + 1;
		ret_prog[frame] = subprog;

		/* find the callee */
		i = i + insn[i].imm + 1;
		subprog = find_subprog(env, i);
		if (subprog < 0) {
			WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
				  i);
			return -EFAULT;
		}
		subprog++;
		frame++;
		if (frame >= MAX_CALL_FRAMES) {
			WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
			return -EFAULT;
		}
		goto process_func;
	}
	/* end of for() loop means the last insn of the 'subprog'
	 * was reached. Doesn't matter whether it was JA or EXIT
	 */
	if (frame == 0)
		return 0;
	depth -= round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
	frame--;
	i = ret_insn[frame];
	subprog = ret_prog[frame];
	goto continue_func;
}

#ifndef CONFIG_BPF_JIT_ALWAYS_ON
static int get_callee_stack_depth(struct bpf_verifier_env *env,
				  const struct bpf_insn *insn, int idx)
{
	int start = idx + insn->imm + 1, subprog;

	subprog = find_subprog(env, start);
	if (subprog < 0) {
		WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
			  start);
		return -EFAULT;
	}
	subprog++;
	return env->subprog_stack_depth[subprog];
}
#endif

/* truncate register to smaller size (in bytes)
 * must be called with size < BPF_REG_SIZE
 */
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
{
	u64 mask;

	/* clear high bits in bit representation */
	reg->var_off = tnum_cast(reg->var_off, size);

	/* fix arithmetic bounds */
	mask = ((u64)1 << (size * 8)) - 1;
	if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
		reg->umin_value &= mask;
		reg->umax_value &= mask;
	} else {
		reg->umin_value = 0;
		reg->umax_value = mask;
	}
	reg->smin_value = reg->umin_value;
	reg->smax_value = reg->umax_value;
}

/* check whether memory at (regno + off) is accessible for t = (read | write)
 * if t==write, value_regno is a register which value is stored into memory
 * if t==read, value_regno is a register which will receive the value from memory
 * if t==write && value_regno==-1, some unknown value is stored into memory
 * if t==read && value_regno==-1, don't care what we read from memory
 */
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
			    int off, int bpf_size, enum bpf_access_type t,
			    int value_regno, bool strict_alignment_once)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = regs + regno;
	struct bpf_func_state *state;
	int size, err = 0;

	size = bpf_size_to_bytes(bpf_size);
	if (size < 0)
		return size;

	/* alignment checks will add in reg->off themselves */
	err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
	if (err)
		return err;

	/* for access checks, reg->off is just part of off */
	off += reg->off;

	if (reg->type == PTR_TO_MAP_VALUE) {
		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into map\n", value_regno);
			return -EACCES;
		}

		err = check_map_access(env, regno, off, size, false);
		if (!err && t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);

	} else if (reg->type == PTR_TO_CTX) {
		enum bpf_reg_type reg_type = SCALAR_VALUE;

		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into ctx\n", value_regno);
			return -EACCES;
		}
		/* ctx accesses must be at a fixed offset, so that we can
		 * determine what type of data were returned.
		 */
		if (reg->off) {
			verbose(env,
				"dereference of modified ctx ptr R%d off=%d+%d, ctx+const is allowed, ctx+const+const is not\n",
				regno, reg->off, off - reg->off);
			return -EACCES;
		}
		if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
			char tn_buf[48];

			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
			verbose(env,
				"variable ctx access var_off=%s off=%d size=%d",
				tn_buf, off, size);
			return -EACCES;
		}
		err = check_ctx_access(env, insn_idx, off, size, t, &reg_type);
		if (!err && t == BPF_READ && value_regno >= 0) {
			/* ctx access returns either a scalar, or a
			 * PTR_TO_PACKET[_META,_END]. In the latter
			 * case, we know the offset is zero.
			 */
			if (reg_type == SCALAR_VALUE)
				mark_reg_unknown(env, regs, value_regno);
			else
				mark_reg_known_zero(env, regs,
						    value_regno);
			regs[value_regno].id = 0;
			regs[value_regno].off = 0;
			regs[value_regno].range = 0;
			regs[value_regno].type = reg_type;
		}

	} else if (reg->type == PTR_TO_STACK) {
		/* stack accesses must be at a fixed offset, so that we can
		 * determine what type of data were returned.
		 * See check_stack_read().
		 */
		if (!tnum_is_const(reg->var_off)) {
			char tn_buf[48];

			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
			verbose(env, "variable stack access var_off=%s off=%d size=%d",
				tn_buf, off, size);
			return -EACCES;
		}
		off += reg->var_off.value;
		if (off >= 0 || off < -MAX_BPF_STACK) {
			verbose(env, "invalid stack off=%d size=%d\n", off,
				size);
			return -EACCES;
		}

		state = func(env, reg);
		err = update_stack_depth(env, state, off);
		if (err)
			return err;

		if (t == BPF_WRITE)
			err = check_stack_write(env, state, off, size,
						value_regno, insn_idx);
		else
			err = check_stack_read(env, state, off, size,
					       value_regno);
	} else if (reg_is_pkt_pointer(reg)) {
		if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
			verbose(env, "cannot write into packet\n");
			return -EACCES;
		}
		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into packet\n",
				value_regno);
			return -EACCES;
		}
		err = check_packet_access(env, regno, off, size, false);
		if (!err && t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else {
		verbose(env, "R%d invalid mem access '%s'\n", regno,
			reg_type_str[reg->type]);
		return -EACCES;
	}

	if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
	    regs[value_regno].type == SCALAR_VALUE) {
		/* b/h/w load zero-extends, mark upper bits as known 0 */
		coerce_reg_to_size(&regs[value_regno], size);
	}
	return err;
}

static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
{
	int err;

	if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
	    insn->imm != 0) {
		verbose(env, "BPF_XADD uses reserved fields\n");
		return -EINVAL;
	}

	/* check src1 operand */
	err = check_reg_arg(env, insn->src_reg, SRC_OP);
	if (err)
		return err;

	/* check src2 operand */
	err = check_reg_arg(env, insn->dst_reg, SRC_OP);
	if (err)
		return err;

	if (is_pointer_value(env, insn->src_reg)) {
		verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
		return -EACCES;
	}

	if (is_ctx_reg(env, insn->dst_reg) ||
	    is_pkt_reg(env, insn->dst_reg)) {
		verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
			insn->dst_reg, is_ctx_reg(env, insn->dst_reg) ?
			"context" : "packet");
		return -EACCES;
	}

	/* check whether atomic_add can read the memory */
	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
			       BPF_SIZE(insn->code), BPF_READ, -1, true);
	if (err)
		return err;

	/* check whether atomic_add can write into the same memory */
	return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
				BPF_SIZE(insn->code), BPF_WRITE, -1, true);
}

/* when register 'regno' is passed into function that will read 'access_size'
 * bytes from that pointer, make sure that it's within stack boundary
 * and all elements of stack are initialized.
 * Unlike most pointer bounds-checking functions, this one doesn't take an
 * 'off' argument, so it has to add in reg->off itself.
 */
static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
				int access_size, bool zero_size_allowed,
				struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *reg = cur_regs(env) + regno;
	struct bpf_func_state *state = func(env, reg);
	int off, i, slot, spi;

	if (reg->type != PTR_TO_STACK) {
		/* Allow zero-byte read from NULL, regardless of pointer type */
		if (zero_size_allowed && access_size == 0 &&
		    register_is_null(reg))
			return 0;

		verbose(env, "R%d type=%s expected=%s\n", regno,
			reg_type_str[reg->type],
			reg_type_str[PTR_TO_STACK]);
		return -EACCES;
	}

	/* Only allow fixed-offset stack reads */
	if (!tnum_is_const(reg->var_off)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "invalid variable stack read R%d var_off=%s\n",
			regno, tn_buf);
		return -EACCES;
	}
	off = reg->off + reg->var_off.value;
	if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
	    access_size < 0 || (access_size == 0 && !zero_size_allowed)) {
		verbose(env, "invalid stack type R%d off=%d access_size=%d\n",
			regno, off, access_size);
		return -EACCES;
	}

	if (meta && meta->raw_mode) {
		meta->access_size = access_size;
		meta->regno = regno;
		return 0;
	}

	for (i = 0; i < access_size; i++) {
		u8 *stype;

		slot = -(off + i) - 1;
		spi = slot / BPF_REG_SIZE;
		if (state->allocated_stack <= slot)
			goto err;
		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
		if (*stype == STACK_MISC)
			goto mark;
		if (*stype == STACK_ZERO) {
			/* helper can write anything into the stack */
			*stype = STACK_MISC;
			goto mark;
		}
err:
		verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
			off, i, access_size);
		return -EACCES;
mark:
		/* reading any byte out of 8-byte 'spill_slot' will cause
		 * the whole slot to be marked as 'read'
		 */
		mark_stack_slot_read(env, env->cur_state, env->cur_state->parent,
				     spi, state->frameno);
	}
	return update_stack_depth(env, state, off);
}

static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
				   int access_size, bool zero_size_allowed,
				   struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];

	switch (reg->type) {
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
		return check_packet_access(env, regno, reg->off, access_size,
					   zero_size_allowed);
	case PTR_TO_MAP_VALUE:
		return check_map_access(env, regno, reg->off, access_size,
					zero_size_allowed);
	default: /* scalar_value|ptr_to_stack or invalid ptr */
		return check_stack_boundary(env, regno, access_size,
					    zero_size_allowed, meta);
	}
}

static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
{
	return type == ARG_PTR_TO_MEM ||
	       type == ARG_PTR_TO_MEM_OR_NULL ||
	       type == ARG_PTR_TO_UNINIT_MEM;
}

static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
	return type == ARG_CONST_SIZE ||
	       type == ARG_CONST_SIZE_OR_ZERO;
}

static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
			  enum bpf_arg_type arg_type,
			  struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	enum bpf_reg_type expected_type, type = reg->type;
	int err = 0;

	if (arg_type == ARG_DONTCARE)
		return 0;

	err = check_reg_arg(env, regno, SRC_OP);
	if (err)
		return err;

	if (arg_type == ARG_ANYTHING) {
		if (is_pointer_value(env, regno)) {
			verbose(env, "R%d leaks addr into helper function\n",
				regno);
			return -EACCES;
		}
		return 0;
	}

	if (type_is_pkt_pointer(type) &&
	    !may_access_direct_pkt_data(env, meta, BPF_READ)) {
		verbose(env, "helper access to the packet is not allowed\n");
		return -EACCES;
	}

	if (arg_type == ARG_PTR_TO_MAP_KEY ||
	    arg_type == ARG_PTR_TO_MAP_VALUE) {
		expected_type = PTR_TO_STACK;
		if (!type_is_pkt_pointer(type) &&
		    type != expected_type)
			goto err_type;
	} else if (arg_type == ARG_CONST_SIZE ||
		   arg_type == ARG_CONST_SIZE_OR_ZERO) {
		expected_type = SCALAR_VALUE;
		if (type != expected_type)
			goto err_type;
	} else if (arg_type == ARG_CONST_MAP_PTR) {
		expected_type = CONST_PTR_TO_MAP;
		if (type != expected_type)
			goto err_type;
	} else if (arg_type == ARG_PTR_TO_CTX) {
		expected_type = PTR_TO_CTX;
		if (type != expected_type)
			goto err_type;
	} else if (arg_type_is_mem_ptr(arg_type)) {
		expected_type = PTR_TO_STACK;
		/* One exception here. In case function allows for NULL to be
		 * passed in as argument, it's a SCALAR_VALUE type. Final test
		 * happens during stack boundary checking.
		 */
		if (register_is_null(reg) &&
		    arg_type == ARG_PTR_TO_MEM_OR_NULL)
			/* final test in check_stack_boundary() */;
		else if (!type_is_pkt_pointer(type) &&
			 type != PTR_TO_MAP_VALUE &&
			 type != expected_type)
			goto err_type;
		meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
	} else {
		verbose(env, "unsupported arg_type %d\n", arg_type);
		return -EFAULT;
	}

	if (arg_type == ARG_CONST_MAP_PTR) {
		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
		meta->map_ptr = reg->map_ptr;
	} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
		/* bpf_map_xxx(..., map_ptr, ..., key) call:
		 * check that [key, key + map->key_size) are within
		 * stack limits and initialized
		 */
		if (!meta->map_ptr) {
			/* in function declaration map_ptr must come before
			 * map_key, so that it's verified and known before
			 * we have to check map_key here. Otherwise it means
			 * that kernel subsystem misconfigured verifier
			 */
			verbose(env, "invalid map_ptr to access map->key\n");
			return -EACCES;
		}
		if (type_is_pkt_pointer(type))
			err = check_packet_access(env, regno, reg->off,
						  meta->map_ptr->key_size,
						  false);
		else
			err = check_stack_boundary(env, regno,
						   meta->map_ptr->key_size,
						   false, NULL);
	} else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
		/* bpf_map_xxx(..., map_ptr, ..., value) call:
		 * check [value, value + map->value_size) validity
		 */
		if (!meta->map_ptr) {
			/* kernel subsystem misconfigured verifier */
			verbose(env, "invalid map_ptr to access map->value\n");
			return -EACCES;
		}
		if (type_is_pkt_pointer(type))
			err = check_packet_access(env, regno, reg->off,
						  meta->map_ptr->value_size,
						  false);
		else
			err = check_stack_boundary(env, regno,
						   meta->map_ptr->value_size,
						   false, NULL);
	} else if (arg_type_is_mem_size(arg_type)) {
		bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);

		/* The register is SCALAR_VALUE; the access check
		 * happens using its boundaries.
		 */
		if (!tnum_is_const(reg->var_off))
			/* For unprivileged variable accesses, disable raw
			 * mode so that the program is required to
			 * initialize all the memory that the helper could
			 * just partially fill up.
			 */
			meta = NULL;

		if (reg->smin_value < 0) {
			verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
				regno);
			return -EACCES;
		}

		if (reg->umin_value == 0) {
			err = check_helper_mem_access(env, regno - 1, 0,
						      zero_size_allowed,
						      meta);
			if (err)
				return err;
		}

		if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
			verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
				regno);
			return -EACCES;
		}
		err = check_helper_mem_access(env, regno - 1,
					      reg->umax_value,
					      zero_size_allowed, meta);
	}

	return err;
err_type:
	verbose(env, "R%d type=%s expected=%s\n", regno,
		reg_type_str[type], reg_type_str[expected_type]);
	return -EACCES;
}

static int check_map_func_compatibility(struct bpf_verifier_env *env,
					struct bpf_map *map, int func_id)
{
	if (!map)
		return 0;

	/* We need a two way check, first is from map perspective ... */
	switch (map->map_type) {
	case BPF_MAP_TYPE_PROG_ARRAY:
		if (func_id != BPF_FUNC_tail_call)
			goto error;
		break;
	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
		if (func_id != BPF_FUNC_perf_event_read &&
		    func_id != BPF_FUNC_perf_event_output &&
		    func_id != BPF_FUNC_perf_event_read_value)
			goto error;
		break;
	case BPF_MAP_TYPE_STACK_TRACE:
		if (func_id != BPF_FUNC_get_stackid)
			goto error;
		break;
	case BPF_MAP_TYPE_CGROUP_ARRAY:
		if (func_id != BPF_FUNC_skb_under_cgroup &&
		    func_id != BPF_FUNC_current_task_under_cgroup)
			goto error;
		break;
	/* devmap returns a pointer to a live net_device ifindex that we cannot
	 * allow to be modified from bpf side. So do not allow lookup elements
	 * for now.
	 */
	case BPF_MAP_TYPE_DEVMAP:
		if (func_id != BPF_FUNC_redirect_map)
			goto error;
		break;
	/* Restrict bpf side of cpumap, open when use-cases appear */
	case BPF_MAP_TYPE_CPUMAP:
		if (func_id != BPF_FUNC_redirect_map)
			goto error;
		break;
	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
	case BPF_MAP_TYPE_HASH_OF_MAPS:
		if (func_id != BPF_FUNC_map_lookup_elem)
			goto error;
		break;
	case BPF_MAP_TYPE_SOCKMAP:
		if (func_id != BPF_FUNC_sk_redirect_map &&
		    func_id != BPF_FUNC_sock_map_update &&
		    func_id != BPF_FUNC_map_delete_elem &&
		    func_id != BPF_FUNC_msg_redirect_map)
			goto error;
		break;
	default:
		break;
	}

	/* ... and second from the function itself. */
	switch (func_id) {
	case BPF_FUNC_tail_call:
		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
			goto error;
		if (env->subprog_cnt) {
			verbose(