flow: revert previous commit

[smatch.git] / smatch_kernel_user_data.c

/*
 * Copyright (C) 2011 Dan Carpenter.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
 */

/*
 * There are a couple checks that try to see if a variable
 * comes from the user.  It would be better to unify them
 * into one place.  Also it we should follow the data down
 * the call paths.  Hence this file.
 */

#include "smatch.h"
#include "smatch_slist.h"
#include "smatch_extra.h"

static int my_id;
static int my_call_id;

static struct expression *ignore_clear;

STATE(called);
static unsigned long func_gets_user_data;

struct user_fn_info {
        const char *name;
        int type;
        int param;
        const char *key;
        const sval_t *implies_start, *implies_end;
        func_hook *call_back;
};

static struct user_fn_info func_table[] = {
        { "brcmf_fweh_dequeue_event", USER_DATA, -1, "&$->emsg" },
        { "cfg80211_find_elem_match", USER_DATA, -1, "$" },
        { "iov_iter_count", USER_DATA, -1, "$" },
        { "wilc_wlan_rxq_remove", USER_DATA, -1, "$->buffer" },
        { "cfg80211_find_vendor_ie", USER_DATA, -1, "$" },
};

static const char *kstr_funcs[] = {
        "kstrtoull", "kstrtoll", "kstrtoul", "kstrtol", "kstrtouint",
        "kstrtoint", "kstrtou64", "kstrtos64", "kstrtou32", "kstrtos32",
        "kstrtou16", "kstrtos16", "kstrtou8", "kstrtos8", "kstrtoull_from_user"
        "kstrtoll_from_user", "kstrtoul_from_user", "kstrtol_from_user",
        "kstrtouint_from_user", "kstrtoint_from_user", "kstrtou16_from_user",
        "kstrtos16_from_user", "kstrtou8_from_user", "kstrtos8_from_user",
        "kstrtou64_from_user", "kstrtos64_from_user", "kstrtou32_from_user",
        "kstrtos32_from_user",
};

static const char *returns_user_data[] = {
        "simple_strtol", "simple_strtoll", "simple_strtoul", "simple_strtoull",
        "kvm_register_read", "xdr_inline_decode",
};

static struct smatch_state *empty_state(struct sm_state *sm)
{
        return alloc_estate_empty();
}

static struct smatch_state *new_state(struct symbol *type)
{
        struct smatch_state *state;

        if (!type || type_is_ptr(type))
                return NULL;

        state = alloc_estate_whole(type);
        estate_set_new(state);
        return state;
}

static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
{
        struct smatch_state *user = cur->state;
        struct smatch_state *extra;
        struct smatch_state *state;
        struct range_list *rl;

        extra = __get_state(SMATCH_EXTRA, cur->name, cur->sym);
        if (!extra)
                return;
        rl = rl_intersection(estate_rl(user), estate_rl(extra));
        state = alloc_estate_rl(clone_rl(rl));
        if (estate_capped(user) || is_capped_var_sym(cur->name, cur->sym))
                estate_set_capped(state);
        if (estate_treat_untagged(user))
                estate_set_treat_untagged(state);
        if (estates_equiv(state, cur->state))
                return;
        if (estate_new(cur->state))
                estate_set_new(state);
        set_state(my_id, cur->name, cur->sym, state);
}

static void extra_nomod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
{
        struct smatch_state *user, *new;
        struct range_list *rl;

        user = __get_state(my_id, name, sym);
        if (!user)
                return;
        rl = rl_intersection(estate_rl(user), estate_rl(state));
        if (rl_equiv(rl, estate_rl(user)))
                return;
        new = alloc_estate_rl(rl);
        if (estate_capped(user))
                estate_set_capped(new);
        if (estate_treat_untagged(user))
                estate_set_treat_untagged(new);
        set_state(my_id, name, sym, new);
}

static void store_type_info(struct expression *expr, struct smatch_state *state)
{
        struct symbol *type;
        char *type_str, *member;

        if (__in_fake_assign)
                return;

        if (!estate_rl(state))
                return;

        expr = strip_expr(expr);
        if (!expr || expr->type != EXPR_DEREF || !expr->member)
                return;

        type = get_type(expr->deref);
        if (!type || !type->ident)
                return;

        type_str = type_to_str(type);
        if (!type_str)
                return;
        member = get_member_name(expr);
        if (!member)
                return;

        sql_insert_function_type_info(USER_DATA, type_str, member, state->name);
}

static void set_user_data(struct expression *expr, struct smatch_state *state)
{
        store_type_info(expr, state);
        set_state_expr(my_id, expr, state);
}

static bool user_rl_known(struct expression *expr)
{
        struct range_list *rl;
        sval_t close_to_max;

        if (!get_user_rl(expr, &rl))
                return true;

        close_to_max = sval_type_max(rl_type(rl));
        close_to_max.value -= 100;

        if (sval_cmp(rl_max(rl), close_to_max) >= 0)
                return false;
        return true;
}

static bool is_array_index_mask_nospec(struct expression *expr)
{
        struct expression *orig;

        orig = get_assigned_expr(expr);
        if (!orig || orig->type != EXPR_CALL)
                return false;
        return sym_name_is("array_index_mask_nospec", orig->fn);
}

static bool binop_capped(struct expression *expr)
{
        struct range_list *left_rl;
        int comparison;
        sval_t sval;

        if (expr->op == '-' && get_user_rl(expr->left, &left_rl)) {
                if (user_rl_capped(expr->left))
                        return true;
                comparison = get_comparison(expr->left, expr->right);
                if (comparison && show_special(comparison)[0] == '>')
                        return true;
                return false;
        }

        if (expr->op == '&' || expr->op == '%') {
                bool left_user, left_capped, right_user, right_capped;

                if (!get_value(expr->right, &sval) && is_capped(expr->right))
                        return true;
                if (is_array_index_mask_nospec(expr->right))
                        return true;
                if (is_capped(expr->left))
                        return true;
                left_user = is_user_rl(expr->left);
                right_user = is_user_rl(expr->right);
                if (!left_user && !right_user)
                        return true;

                left_capped = user_rl_capped(expr->left);
                right_capped = user_rl_capped(expr->right);

                if (left_user && left_capped) {
                        if (!right_user)
                                return true;
                        if (right_user && right_capped)
                                return true;
                        return false;
                }
                if (right_user && right_capped) {
                        if (!left_user)
                                return true;
                        return false;
                }
                return false;
        }

        /*
         * Generally "capped" means that we capped it to an unknown value.
         * This is useful because if Smatch doesn't know what the value is then
         * we have to trust that it is correct.  But if we known cap value is
         * 100 then we can check if 100 is correct and complain if it's wrong.
         *
         * So then the problem is with BINOP when we take a capped variable
         * plus a user variable which is clamped to a known range (uncapped)
         * the result should be capped.
         */
        if ((user_rl_capped(expr->left) || user_rl_known(expr->left)) &&
            (user_rl_capped(expr->right) || user_rl_known(expr->right)))
                return true;

        return false;
}

bool user_rl_capped_var_sym(const char *name, struct symbol *sym)
{
        struct smatch_state *state;

        state = get_state(my_id, name, sym);
        if (state)
                return estate_capped(state);

        return true;
}

bool user_rl_capped(struct expression *expr)
{
        struct smatch_state *state;
        struct range_list *rl;
        sval_t sval;

        expr = strip_expr(expr);
        if (!expr)
                return false;
        if (get_value(expr, &sval))
                return true;
        if (expr->type == EXPR_BINOP)
                return binop_capped(expr);
        if ((expr->type == EXPR_PREOP || expr->type == EXPR_POSTOP) &&
            (expr->op == SPECIAL_INCREMENT || expr->op == SPECIAL_DECREMENT))
                return user_rl_capped(expr->unop);
        state = get_state_expr(my_id, expr);
        if (state)
                return estate_capped(state);

        if (!get_user_rl(expr, &rl)) {
                /*
                 * The non user data parts of a binop are capped and
                 * also empty user rl states are capped.
                 */
                return true;
        }

        if (rl_to_sval(rl, &sval))
                return true;

        return false;  /* uncapped user data */
}

bool user_rl_treat_untagged(struct expression *expr)
{
        struct smatch_state *state;
        struct range_list *rl;
        sval_t sval;

        expr = strip_expr(expr);
        if (!expr)
                return false;
        if (get_value(expr, &sval))
                return true;

        state = get_state_expr(my_id, expr);
        if (state)
                return estate_treat_untagged(state);

        if (get_user_rl(expr, &rl))
                return false;  /* uncapped user data */

        return true;  /* not actually user data */
}

static void tag_inner_struct_members(struct expression *expr, struct symbol *member)
{
        struct expression *edge_member;
        struct symbol *base = get_real_base_type(member);
        struct symbol *tmp;

        if (member->ident)
                expr = member_expression(expr, '.', member->ident);

        FOR_EACH_PTR(base->symbol_list, tmp) {
                struct symbol *type;

                type = get_real_base_type(tmp);
                if (!type)
                        continue;

                if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
                        tag_inner_struct_members(expr, tmp);
                        continue;
                }

                if (!tmp->ident)
                        continue;

                edge_member = member_expression(expr, '.', tmp->ident);
                set_user_data(edge_member, new_state(type));
        } END_FOR_EACH_PTR(tmp);
}

void __set_user_string(struct expression *expr);
static void tag_struct_members(struct symbol *type, struct expression *expr)
{
        struct symbol *tmp, *member_type;
        struct expression *member;
        int op = '*';

        if (expr->type == EXPR_PREOP && expr->op == '&') {
                expr = strip_expr(expr->unop);
                op = '.';
        }

        FOR_EACH_PTR(type->symbol_list, tmp) {
                member_type = get_real_base_type(tmp);
                if (!member_type)
                        continue;

                if (member_type->type == SYM_UNION ||
                    member_type->type == SYM_STRUCT) {
                        tag_inner_struct_members(expr, tmp);
                        continue;
                }

                if (!tmp->ident)
                        continue;

                member = member_expression(expr, op, tmp->ident);
                if (member_type->type == SYM_ARRAY) {
                        set_points_to_user_data(member, true);
                } else {
                        set_user_data(member, new_state(get_type(member)));
                }
        } END_FOR_EACH_PTR(tmp);
}

static void tag_base_type(struct expression *expr)
{
        if (expr->type == EXPR_PREOP && expr->op == '&')
                expr = strip_expr(expr->unop);
        else
                expr = deref_expression(expr);
        set_user_data(expr, new_state(get_type(expr)));
}

static void tag_as_user_data(struct expression *expr)
{
        struct symbol *type;

        expr = strip_expr(expr);

        type = get_type(expr);
        if (!type || type->type != SYM_PTR)
                return;
        type = get_real_base_type(type);
        if (!type)
                return;
        if (type == &void_ctype) {
                set_user_data(deref_expression(expr), new_state(&ulong_ctype));
                return;
        }
        if (type->type == SYM_BASETYPE) {
                if (expr->type != EXPR_PREOP && expr->op != '&')
                        set_points_to_user_data(expr, true);
                tag_base_type(expr);
                return;
        }
        if (type->type == SYM_STRUCT || type->type == SYM_UNION) {
                if (expr->type != EXPR_PREOP || expr->op != '&')
                        expr = deref_expression(expr);
                else
                        set_user_data(deref_expression(expr), new_state(&ulong_ctype));
                tag_struct_members(type, expr);
        }
}

static void match_user_copy(const char *fn, struct expression *expr, void *_param)
{
        int param = PTR_INT(_param);
        struct expression *dest;

        func_gets_user_data = true;
        ignore_clear = expr;

        dest = get_argument_from_call_expr(expr->args, param);
        dest = strip_expr(dest);
        if (!dest)
                return;
        tag_as_user_data(dest);
}

static int is_dev_attr_name(struct expression *expr)
{
        char *name;
        int ret = 0;

        name = expr_to_str(expr);
        if (!name)
                return 0;
        if (strstr(name, "->attr.name"))
                ret = 1;
        free_string(name);
        return ret;
}

static bool is_percent_n(struct expression *expr, int pos)
{
        char *p;
        int cnt = 0;

        if (!expr)
                return false;
        if (expr->type != EXPR_STRING || !expr->string)
                return false;

        p = expr->string->data;
        while (*p) {
                if (p[0] != '%' ||
                    (p[0] == '%' && p[1] == '%')) {
                        p++;
                        continue;
                }
                if (pos != cnt) {
                        cnt++;
                        p++;
                        continue;
                }
                if (p[1] == 'n')
                        return true;
                return false;
        }

        return false;
}

static void match_sscanf(const char *fn, struct expression *expr, void *unused)
{
        struct expression *str, *format, *arg;
        int i;

        func_gets_user_data = true;

        str = get_argument_from_call_expr(expr->args, 0);
        if (is_dev_attr_name(str))
                return;

        format = get_argument_from_call_expr(expr->args, 1);
        if (is_dev_attr_name(format))
                return;

        i = -1;
        FOR_EACH_PTR(expr->args, arg) {
                i++;
                if (i < 2)
                        continue;
                if (is_percent_n(format, i - 2))
                        continue;
                tag_as_user_data(arg);
        } END_FOR_EACH_PTR(arg);
}

static int get_rl_from_function(struct expression *expr, struct range_list **rl)
{
        int i;

        if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
            !expr->fn->symbol_name)
                return 0;

        for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
                if (strcmp(expr->fn->symbol_name->name, returns_user_data[i]) == 0) {
                        *rl = alloc_whole_rl(get_type(expr));
                        return 1;
                }
        }
        return 0;
}

static int comes_from_skb_data(struct expression *expr)
{
        expr = strip_expr(expr);
        if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
                return 0;

        expr = strip_expr(expr->unop);
        if (!expr)
                return 0;
        if (expr->type == EXPR_BINOP && expr->op == '+')
                expr = strip_expr(expr->left);

        return is_skb_data(expr);
}

static int handle_get_user(struct expression *expr)
{
        char *name;
        int ret = 0;

        name = get_macro_name(expr->pos);
        if (!name || strcmp(name, "get_user") != 0)
                return 0;

        name = expr_to_var(expr->right);
        if (!name || (strcmp(name, "__val_gu") != 0 && strcmp(name, "__gu_val") != 0))
                goto free;
        set_user_data(expr->left, new_state(get_type(expr->left)));
        ret = 1;
free:
        free_string(name);
        return ret;
}

static bool state_is_new(struct expression *expr)
{
        struct smatch_state *state;

        state = get_state_expr(my_id, expr);
        if (estate_new(state))
                return true;

        if (expr->type == EXPR_BINOP) {
                if (state_is_new(expr->left))
                        return true;
                if (state_is_new(expr->right))
                        return true;
        }
        return false;
}

static struct range_list *strip_negatives(struct range_list *rl)
{
        sval_t min = rl_min(rl);
        sval_t minus_one = { .type = rl_type(rl), .value = -1 };
        sval_t over = { .type = rl_type(rl), .value = INT_MAX + 1ULL };
        sval_t max = sval_type_max(rl_type(rl));

        if (!rl)
                return NULL;

        if (type_unsigned(rl_type(rl)) && type_bits(rl_type(rl)) > 31)
                return remove_range(rl, over, max);

        return remove_range(rl, min, minus_one);
}

static bool handle_op_assign(struct expression *expr)
{
        struct expression *binop_expr;
        struct smatch_state *state;
        struct range_list *rl;

        switch (expr->op) {
        case SPECIAL_ADD_ASSIGN:
        case SPECIAL_SUB_ASSIGN:
        case SPECIAL_AND_ASSIGN:
        case SPECIAL_MOD_ASSIGN:
        case SPECIAL_SHL_ASSIGN:
        case SPECIAL_SHR_ASSIGN:
        case SPECIAL_OR_ASSIGN:
        case SPECIAL_XOR_ASSIGN:
        case SPECIAL_MUL_ASSIGN:
        case SPECIAL_DIV_ASSIGN:
                binop_expr = binop_expression(expr->left,
                                              op_remove_assign(expr->op),
                                              expr->right);
                if (!get_user_rl(binop_expr, &rl))
                        return true;

                rl = cast_rl(get_type(expr->left), rl);
                state = alloc_estate_rl(rl);
                if (expr->op == SPECIAL_AND_ASSIGN ||
                    expr->op == SPECIAL_MOD_ASSIGN ||
                    user_rl_capped(binop_expr))
                        estate_set_capped(state);
                if (user_rl_treat_untagged(expr->left))
                        estate_set_treat_untagged(state);
                if (state_is_new(binop_expr))
                        estate_set_new(state);
                estate_set_assigned(state);
                set_user_data(expr->left, state);
                return true;
        }
        return false;
}

static void handle_derefed_pointers(struct expression *expr, bool is_new)
{
        expr = strip_expr(expr);
        if (expr->type != EXPR_PREOP ||
            expr->op != '*')
                return;
        expr = strip_expr(expr->unop);
        set_points_to_user_data(expr, is_new);
}

static void match_assign(struct expression *expr)
{
        struct symbol *left_type, *right_type;
        struct range_list *rl = NULL;
        static struct expression *handled;
        struct smatch_state *state;
        struct expression *faked;
        bool is_capped = false;
        bool is_new = false;

        left_type = get_type(expr->left);
        if (left_type == &void_ctype)
                return;

        faked = get_faked_expression();
        if (faked && faked == ignore_clear)
                return;

        /* FIXME: handle fake array assignments frob(&user_array[x]); */

        if (faked &&
            faked->type == EXPR_ASSIGNMENT &&
            points_to_user_data(faked->right)) {
                if (is_skb_data(faked->right))
                        func_gets_user_data = true;
                rl = alloc_whole_rl(get_type(expr->left));
                is_new = true;
                goto set;
        }

        if (faked && faked == handled)
                return;
        if (is_fake_call(expr->right))
                goto clear_old_state;
        if (handle_get_user(expr))
                return;
        if (points_to_user_data(expr->right) &&
            is_struct_ptr(get_type(expr->left))) {
                handled = expr;
                // This should be handled by smatch_points_to_user_data.c
                // set_points_to_user_data(expr->left);
        }

        if (handle_op_assign(expr))
                return;
        if (expr->op != '=')
                goto clear_old_state;

        /* Handled by DB code */
        if (expr->right->type == EXPR_CALL)
                return;

        if (faked)
                disable_type_val_lookups();
        get_user_rl(expr->right, &rl);
        if (faked)
                enable_type_val_lookups();
        if (!rl)
                goto clear_old_state;

        is_capped = user_rl_capped(expr->right);
        is_new = state_is_new(expr->right);

set:
        right_type = get_type(expr->right);
        if (type_is_ptr(left_type)) {
                if (right_type && right_type->type == SYM_ARRAY)
                        set_points_to_user_data(expr->left, is_new);
                return;
        }

        rl = cast_rl(left_type, rl);
        if (is_capped && type_unsigned(right_type) && type_signed(left_type))
                rl = strip_negatives(rl);
        state = alloc_estate_rl(rl);
        if (is_new)
                estate_set_new(state);
        if (is_capped)
                estate_set_capped(state);
        if (user_rl_treat_untagged(expr->right))
                estate_set_treat_untagged(state);
        estate_set_assigned(state);

        set_user_data(expr->left, state);
        handle_derefed_pointers(expr->left, is_new);
        return;

clear_old_state:

        /*
         * HACK ALERT!!!  This should be at the start of the function.  The
         * the problem is that handling "pointer = array;" assignments is
         * handled in this function instead of in kernel_points_to_user_data.c.
         */
        if (type_is_ptr(left_type))
                return;

        if (get_state_expr(my_id, expr->left))
                set_user_data(expr->left, alloc_estate_empty());
}

static void handle_eq_noteq(struct expression *expr)
{
        struct smatch_state *left_orig, *right_orig;

        left_orig = get_state_expr(my_id, expr->left);
        right_orig = get_state_expr(my_id, expr->right);

        if (!left_orig && !right_orig)
                return;
        if (left_orig && right_orig)
                return;

        if (left_orig) {
                set_true_false_states_expr(my_id, expr->left,
                                expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
                                expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
        } else {
                set_true_false_states_expr(my_id, expr->right,
                                expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
                                expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
        }
}

static void handle_compare(struct expression *expr)
{
        struct expression  *left, *right;
        struct range_list *left_rl = NULL;
        struct range_list *right_rl = NULL;
        struct range_list *user_rl;
        struct smatch_state *capped_state;
        struct smatch_state *left_true = NULL;
        struct smatch_state *left_false = NULL;
        struct smatch_state *right_true = NULL;
        struct smatch_state *right_false = NULL;
        struct symbol *type;
        sval_t sval;

        left = strip_expr(expr->left);
        right = strip_expr(expr->right);

        while (left->type == EXPR_ASSIGNMENT)
                left = strip_expr(left->left);

        /*
         * Conditions are mostly handled by smatch_extra.c, but there are some
         * times where the exact values are not known so we can't do that.
         *
         * Normally, we might consider using smatch_capped.c to supliment smatch
         * extra but that doesn't work when we merge unknown uncapped kernel
         * data with unknown capped user data.  The result is uncapped user
         * data.  We need to keep it separate and say that the user data is
         * capped.  In the past, I would have marked this as just regular
         * kernel data (not user data) but we can't do that these days because
         * we need to track user data for Spectre.
         *
         * The other situation which we have to handle is when we do have an
         * int and we compare against an unknown unsigned kernel variable.  In
         * that situation we assume that the kernel data is less than INT_MAX.
         * Otherwise then we get all sorts of array underflow false positives.
         *
         */

        /* Handled in smatch_extra.c */
        if (get_implied_value(left, &sval) ||
            get_implied_value(right, &sval))
                return;

        get_user_rl(left, &left_rl);
        get_user_rl(right, &right_rl);

        /* nothing to do */
        if (!left_rl && !right_rl)
                return;
        /* if both sides are user data that's not a good limit */
        if (left_rl && right_rl)
                return;

        if (left_rl)
                user_rl = left_rl;
        else
                user_rl = right_rl;

        type = get_type(expr);
        if (type_unsigned(type))
                user_rl = strip_negatives(user_rl);
        capped_state = alloc_estate_rl(user_rl);
        estate_set_capped(capped_state);

        switch (expr->op) {
        case '<':
        case SPECIAL_UNSIGNED_LT:
        case SPECIAL_LTE:
        case SPECIAL_UNSIGNED_LTE:
                if (left_rl)
                        left_true = capped_state;
                else
                        right_false = capped_state;
                break;
        case '>':
        case SPECIAL_UNSIGNED_GT:
        case SPECIAL_GTE:
        case SPECIAL_UNSIGNED_GTE:
                if (left_rl)
                        left_false = capped_state;
                else
                        right_true = capped_state;
                break;
        }

        set_true_false_states_expr(my_id, left, left_true, left_false);
        set_true_false_states_expr(my_id, right, right_true, right_false);
}

static void match_condition(struct expression *expr)
{
        if (expr->type != EXPR_COMPARE)
                return;

        if (expr->op == SPECIAL_EQUAL ||
            expr->op == SPECIAL_NOTEQUAL) {
                handle_eq_noteq(expr);
                return;
        }

        handle_compare(expr);
}

static void match_returns_user_rl(const char *fn, struct expression *expr, void *unused)
{
        func_gets_user_data = true;
}

static int get_user_macro_rl(struct expression *expr, struct range_list **rl)
{
        struct expression *parent;
        char *macro;

        if (!expr)
                return 0;

        macro = get_macro_name(expr->pos);
        if (!macro)
                return 0;

        /* handle ntohl(foo[i]) where "i" is trusted */
        parent = expr_get_parent_expr(expr);
        while (parent && parent->type != EXPR_BINOP)
                parent = expr_get_parent_expr(parent);
        if (parent && parent->type == EXPR_BINOP) {
                char *parent_macro = get_macro_name(parent->pos);

                if (parent_macro && strcmp(macro, parent_macro) == 0)
                        return 0;
        }

        if (strcmp(macro, "ntohl") == 0) {
                *rl = alloc_whole_rl(&uint_ctype);
                return 1;
        }
        if (strcmp(macro, "ntohs") == 0) {
                *rl = alloc_whole_rl(&ushort_ctype);
                return 1;
        }
        return 0;
}

static int has_user_data(struct symbol *sym)
{
        struct sm_state *tmp;

        FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
                if (tmp->sym == sym)
                        return 1;
        } END_FOR_EACH_SM(tmp);
        return 0;
}

bool we_pass_user_data(struct expression *call)
{
        struct expression *arg;
        struct symbol *sym;

        FOR_EACH_PTR(call->args, arg) {
                if (points_to_user_data(arg))
                        return true;
                sym = expr_to_sym(arg);
                if (!sym)
                        continue;
                if (has_user_data(sym))
                        return true;
        } END_FOR_EACH_PTR(arg);

        return false;
}

// TODO: faked_assign this should already be handled
static int db_returned_user_rl(struct expression *call, struct range_list **rl)
{
        struct smatch_state *state;
        char buf[48];

        if (is_fake_call(call))
                return 0;
        snprintf(buf, sizeof(buf), "return %p", call);
        state = get_state(my_id, buf, NULL);
        if (!state || !estate_rl(state))
                return 0;
        *rl = estate_rl(state);
        return 1;
}

struct stree *get_user_stree(void)
{
        return get_all_states_stree(my_id);
}

static struct int_stack *user_data_flags, *no_user_data_flags;

static void set_flag(struct int_stack **stack)
{
        int num;

        num = pop_int(stack);
        num = 1;
        push_int(stack, num);
}

struct range_list *var_user_rl(struct expression *expr)
{
        struct smatch_state *state;
        struct range_list *rl;
        struct range_list *absolute_rl;

        if (expr->type == EXPR_PREOP && expr->op == '&') {
                set_flag(&no_user_data_flags);
                return NULL;
        }

        if (expr->type == EXPR_BINOP && expr->op == '%') {
                struct range_list *left, *right;

                if (!get_user_rl(expr->right, &right))
                        return NULL;
                get_absolute_rl(expr->left, &left);
                rl = rl_binop(left, '%', right);
                goto found;
        }

        if (expr->type == EXPR_BINOP && expr->op == '/') {
                struct range_list *left = NULL;
                struct range_list *right = NULL;
                struct range_list *abs_right;

                /*
                 * The specific bug I'm dealing with is:
                 *
                 * foo = capped_user / unknown;
                 *
                 * Instead of just saying foo is now entirely user_rl we should
                 * probably say instead that it is not at all user data.
                 *
                 */

                get_user_rl(expr->left, &left);
                get_user_rl(expr->right, &right);
                get_absolute_rl(expr->right, &abs_right);

                if (left && !right) {
                        rl = rl_binop(left, '/', abs_right);
                        if (sval_cmp(rl_max(left), rl_max(rl)) < 0)
                                set_flag(&no_user_data_flags);
                }

                return NULL;
        }

        if (get_rl_from_function(expr, &rl))
                goto found;

        if (get_user_macro_rl(expr, &rl))
                goto found;

        if (comes_from_skb_data(expr)) {
                rl = alloc_whole_rl(get_type(expr));
                goto found;
        }

        state = get_state_expr(my_id, expr);
        if (state && estate_rl(state)) {
                rl = estate_rl(state);
                goto found;
        }

        if (expr->type == EXPR_CALL && db_returned_user_rl(expr, &rl))
                goto found;

        if (expr->type == EXPR_PREOP && expr->op == '*' &&
            points_to_user_data(expr->unop)) {
                rl = var_to_absolute_rl(expr);
                goto found;
        }

        if (is_array(expr)) {
                struct expression *array = get_array_base(expr);

                if (!get_state_expr(my_id, array)) {
                        set_flag(&no_user_data_flags);
                        return NULL;
                }
        }

        return NULL;
found:
        set_flag(&user_data_flags);
        absolute_rl = var_to_absolute_rl(expr);
        return rl_intersection(rl, absolute_rl);
}

static bool is_ptr_subtract(struct expression *expr)
{
        expr = strip_expr(expr);
        if (!expr)
                return false;
        if (expr->type == EXPR_BINOP && expr->op == '-' &&
            type_is_ptr(get_type(expr->left))) {
                return true;
        }
        return false;
}

int get_user_rl(struct expression *expr, struct range_list **rl)
{
        int user_data, no_user_data;

        if (is_ptr_subtract(expr))
                return 0;

        push_int(&user_data_flags, 0);
        push_int(&no_user_data_flags, 0);

        custom_get_absolute_rl(expr, &var_user_rl, rl);

        user_data = pop_int(&user_data_flags);
        no_user_data = pop_int(&no_user_data_flags);

        if (!user_data || no_user_data)
                *rl = NULL;

        return !!*rl;
}

int is_user_rl(struct expression *expr)
{
        struct range_list *tmp;

        return get_user_rl(expr, &tmp) && tmp;
}

int get_user_rl_var_sym(const char *name, struct symbol *sym, struct range_list **rl)
{
        struct smatch_state *state, *extra;

        state = get_state(my_id, name, sym);
        if (!estate_rl(state))
                return 0;
        *rl = estate_rl(state);

        extra = get_state(SMATCH_EXTRA, name, sym);
        if (estate_rl(extra))
                *rl = rl_intersection(estate_rl(state), estate_rl(extra));

        return 1;
}

bool is_socket_stuff(struct symbol *sym)
{
        struct symbol *type;

        /* This is a hack.
         * Basically I never want to consider an skb or sk as user pointer.
         * The skb->data is already marked as a source of user data, and if
         * anything else is marked as user data it's almost certainly wrong.
         *
         * Ideally, I would figure out where this bogus data is coming from,
         * but possibly it just was stuck in the database from previous updates
         * and can't get cleared out without deleting all user data.  Things
         * like this gets stuck in the DB because of recursion.
         *
         * I could make this a temporary hack, but I keep wanting to do it so
         * I'm just going to make it permanent.  It either doesn't change
         * anything or it makes life better.
         */

        type = get_real_base_type(sym);
        if (!type || type->type != SYM_PTR)
                return false;
        type = get_real_base_type(type);
        if (!type || type->type != SYM_STRUCT || !type->ident)
                return false;

        if (strcmp(type->ident->name, "sk_buff") == 0)
                return true;
        if (strcmp(type->ident->name, "sock") == 0)
                return true;
        if (strcmp(type->ident->name, "socket") == 0)
                return true;

        return false;
}

static void return_info_callback(int return_id, char *return_ranges,
                                 struct expression *returned_expr,
                                 int param,
                                 const char *printed_name,
                                 struct sm_state *sm)
{
        struct smatch_state *extra;
        struct range_list *rl;
        char buf[64];

        if (is_socket_stuff(sm->sym))
                return;
        if (is_ignored_kernel_data(printed_name))
                return;

        if (param >= 0) {
                if (strcmp(printed_name, "$") == 0)
                        return;
                if (!estate_assigned(sm->state) &&
                    !estate_new(sm->state))
                        return;
        }
        rl = estate_rl(sm->state);
        if (!rl)
                return;
        extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
        if (estate_rl(extra))
                rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
        if (!rl)
                return;

        snprintf(buf, sizeof(buf), "%s%s%s",
                 show_rl(rl),
                 estate_capped(sm->state) ? "[c]" : "",
                 estate_treat_untagged(sm->state) ? "[u]" : "");
        sql_insert_return_states(return_id, return_ranges,
                                 estate_new(sm->state) ? USER_DATA_SET : USER_DATA,
                                 param, printed_name, buf);
}

static bool is_ignored_macro(struct position pos)
{
        const char *macro;

        macro = get_macro_name(pos);
        if (!macro)
                return false;
        if (strcmp(macro, "v4l2_subdev_call") == 0)
                return true;
        return false;
}

static void caller_info_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
{
        struct smatch_state *state;
        struct range_list *rl;
        struct symbol *type;
        char buf[64];

        if (is_ignored_macro(call->pos))
                return;

        if (is_socket_stuff(sm->sym))
                return;
        if (is_ignored_kernel_data(printed_name))
                return;

        /*
         * Smatch uses a hack where if we get an unsigned long we say it's
         * both user data and it points to user data.  But if we pass it to a
         * function which takes an int, then it's just user data.  There's not
         * enough bytes for it to be a pointer.
         *
         */
        type = get_arg_type(call->fn, param);
        if (strcmp(printed_name, "$") != 0 && type && type_bits(type) < type_bits(&ptr_ctype))
                return;

        if (strcmp(sm->state->name, "") == 0)
                return;

        state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
        if (!state || !estate_rl(state))
                rl = estate_rl(sm->state);
        else
                rl = rl_intersection(estate_rl(sm->state), estate_rl(state));

        if (!rl)
                return;

        snprintf(buf, sizeof(buf), "%s%s%s", show_rl(rl),
                 estate_capped(sm->state) ? "[c]" : "",
                 estate_treat_untagged(sm->state) ? "[u]" : "");
        sql_insert_caller_info(call, USER_DATA, param, printed_name, buf);
}

static void db_param_set(struct expression *expr, int param, char *key, char *value)
{
        struct expression *arg;
        char *name;
        struct symbol *sym;
        struct smatch_state *state;

        while (expr->type == EXPR_ASSIGNMENT)
                expr = strip_expr(expr->right);
        if (expr->type != EXPR_CALL)
                return;
        if (expr == ignore_clear)
                return;

        arg = get_argument_from_call_expr(expr->args, param);
        if (!arg)
                return;
        name = get_variable_from_key(arg, key, &sym);
        if (!name || !sym)
                goto free;

        state = get_state(my_id, name, sym);
        if (!state)
                goto free;

        set_state(my_id, name, sym, alloc_estate_empty());
free:
        free_string(name);
}

static bool param_data_capped(const char *value)
{
        if (strstr(value, ",c") || strstr(value, "[c"))
                return true;
        return false;
}

static bool param_data_treat_untagged(const char *value)
{
        if (strstr(value, ",u") || strstr(value, "[u"))
                return true;
        return false;
}

static void set_param_user_data(const char *name, struct symbol *sym, char *key, char *value)
{
        struct expression *expr;
        struct range_list *rl = NULL;
        struct smatch_state *state;
        struct symbol *type;
        char *fullname;

        expr = symbol_expression(sym);
        fullname = get_variable_from_key(expr, key, NULL);
        if (!fullname)
                return;

        type = get_member_type_from_key(expr, key);
        if (type && type->type == SYM_STRUCT)
                return;

        if (!type)
                return;

        str_to_rl(type, value, &rl);
        rl = swap_mtag_seed(expr, rl);
        state = alloc_estate_rl(rl);
        if (param_data_capped(value) || is_capped(expr))
                estate_set_capped(state);
        if (param_data_treat_untagged(value) || sym->ctype.as == 5)
                estate_set_treat_untagged(state);
        set_state(my_id, fullname, sym, state);
}

static void set_called(const char *name, struct symbol *sym, char *key, char *value)
{
        set_state(my_call_id, "this_function", NULL, &called);
}

static void match_syscall_definition(struct symbol *sym)
{
        struct symbol *arg;
        char *macro;
        char *name;
        int is_syscall = 0;

        macro = get_macro_name(sym->pos);
        if (macro &&
            (strncmp("SYSCALL_DEFINE", macro, strlen("SYSCALL_DEFINE")) == 0 ||
             strncmp("COMPAT_SYSCALL_DEFINE", macro, strlen("COMPAT_SYSCALL_DEFINE")) == 0))
                is_syscall = 1;

        name = get_function();
        if (!option_no_db && get_state(my_call_id, "this_function", NULL) != &called) {
                if (name && strncmp(name, "sys_", 4) == 0)
                        is_syscall = 1;
        }

        if (name && strncmp(name, "compat_sys_", 11) == 0)
                is_syscall = 1;

        if (!is_syscall)
                return;

        FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
                set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
        } END_FOR_EACH_PTR(arg);
}

#define OLD 0
#define NEW 1

static void store_user_data_return(struct expression *expr, char *key, char *value, bool is_new)
{
        struct smatch_state *state;
        struct range_list *rl;
        struct symbol *type;
        char buf[48];

        if (key[0] != '$')
                return;

        type = get_type(expr);
        snprintf(buf, sizeof(buf), "return %p%s", expr, key + 1);
        call_results_to_rl(expr, type, value, &rl);

        state = alloc_estate_rl(rl);
        if (is_new)
                estate_set_new(state);

        set_state(my_id, buf, NULL, state);
}

static void set_to_user_data(struct expression *expr, char *key, char *value, bool is_new)
{
        struct smatch_state *state;
        char *name;
        struct symbol *sym;
        struct symbol *type;
        struct range_list *rl = NULL;

        type = get_member_type_from_key(expr, key);
        name = get_variable_from_key(expr, key, &sym);
        if (!name || !sym)
                goto free;

        call_results_to_rl(expr, type, value, &rl);

        state = alloc_estate_rl(rl);
        if (param_data_capped(value))
                estate_set_capped(state);
        if (param_data_treat_untagged(value))
                estate_set_treat_untagged(state);
        if (is_new)
                estate_set_new(state);
        estate_set_assigned(state);
        set_state(my_id, name, sym, state);
free:
        free_string(name);
}

static void returns_param_user_data(struct expression *expr, int param, char *key, char *value)
{
        struct expression *arg;
        struct expression *call;

        call = expr;
        while (call->type == EXPR_ASSIGNMENT)
                call = strip_expr(call->right);
        if (call->type != EXPR_CALL)
                return;

        if (!we_pass_user_data(call))
                return;

        if (param == -1) {
                if (expr->type != EXPR_ASSIGNMENT) {
                        // TODO: faked_assign this should all be handled as a fake assignment
                        store_user_data_return(expr, key, value, OLD);
                        return;
                }
                set_to_user_data(expr->left, key, value, OLD);
                return;
        }

        arg = get_argument_from_call_expr(call->args, param);
        if (!arg)
                return;
        set_to_user_data(arg, key, value, OLD);
}

static void returns_param_user_data_set(struct expression *expr, int param, char *key, char *value)
{
        struct expression *arg;

        func_gets_user_data = true;

        if (param == -1) {
                if (expr->type != EXPR_ASSIGNMENT) {
                        store_user_data_return(expr, key, value, NEW);
                        return;
                }
                set_to_user_data(expr->left, key, value, NEW);
                return;
        }

        while (expr->type == EXPR_ASSIGNMENT)
                expr = strip_expr(expr->right);
        if (expr->type != EXPR_CALL)
                return;

        arg = get_argument_from_call_expr(expr->args, param);
        if (!arg)
                return;
        set_to_user_data(arg, key, value, NEW);
}

static void set_param_key_user_data(struct expression *expr, const char *name,
                                    struct symbol *sym, void *data)
{
        struct expression *arg;
        struct symbol *type;

        func_gets_user_data = true;
        arg = gen_expression_from_name_sym(name, sym);
        type = get_type(arg);
        if (type_is_ptr(type))
                tag_as_user_data(arg);
        else
                set_state_expr(my_id, arg, alloc_estate_whole(type));
}

static void match_capped(struct expression *expr, const char *name, struct symbol *sym, void *info)
{
        struct smatch_state *state, *new;

        state = get_state(my_id, name, sym);
        if (!state || estate_capped(state))
                return;

        new = clone_estate(state);
        estate_set_capped(new);

        set_state(my_id, name, sym, new);
}

static void match_function_def(struct symbol *sym)
{
        if (is_user_data_fn(sym))
                func_gets_user_data = true;
}

void register_kernel_user_data(int id)
{
        struct user_fn_info *info;
        int i;

        my_id = id;

        if (option_project != PROJ_KERNEL)
                return;

        set_dynamic_states(my_id);

        add_function_data(&func_gets_user_data);
        add_hook(&match_function_def, FUNC_DEF_HOOK);

        add_unmatched_state_hook(my_id, &empty_state);
        add_extra_nomod_hook(&extra_nomod_hook);
        add_pre_merge_hook(my_id, &pre_merge_hook);
        add_merge_hook(my_id, &merge_estates);

        add_function_hook("copy_from_user", &match_user_copy, INT_PTR(0));
        add_function_hook("__copy_from_user", &match_user_copy, INT_PTR(0));
        add_function_hook("memcpy_fromiovec", &match_user_copy, INT_PTR(0));
        for (i = 0; i < ARRAY_SIZE(kstr_funcs); i++)
                add_function_hook_late(kstr_funcs[i], &match_user_copy, INT_PTR(2));
        add_function_hook("usb_control_msg", &match_user_copy, INT_PTR(6));
        add_function_hook("kvm_read_guest_virt", &match_user_copy, INT_PTR(2));
        add_function_hook("vpu_iface_receive_msg", &match_user_copy, INT_PTR(1));
        add_function_hook("xdr_stream_decode_u32", &match_user_copy, INT_PTR(1));

        for (i = 0; i < ARRAY_SIZE(returns_user_data); i++)
                add_function_hook(returns_user_data[i], &match_returns_user_rl, NULL);

        add_function_hook("sscanf", &match_sscanf, NULL);

        add_hook(&match_syscall_definition, AFTER_DEF_HOOK);

        add_hook(&match_assign, ASSIGNMENT_HOOK);
        select_return_states_hook(PARAM_SET, &db_param_set);
        add_hook(&match_condition, CONDITION_HOOK);

        add_caller_info_callback(my_id, caller_info_callback);
        add_return_info_callback(my_id, return_info_callback);
        select_caller_info_hook(set_param_user_data, USER_DATA);
        select_return_states_hook(USER_DATA, &returns_param_user_data);
        select_return_states_hook(USER_DATA_SET, &returns_param_user_data_set);

        select_return_param_key(CAPPED_DATA, &match_capped);
        add_function_param_key_hook_late("memcpy", &match_capped, 2, "$", NULL);
        add_function_param_key_hook_late("_memcpy", &match_capped, 2, "$", NULL);
        add_function_param_key_hook_late("__memcpy", &match_capped, 2, "$", NULL);
        add_function_param_key_hook_late("memset", &match_capped, 2, "$", NULL);
        add_function_param_key_hook_late("_memset", &match_capped, 2, "$", NULL);
        add_function_param_key_hook_late("__memset", &match_capped, 2, "$", NULL);

        for (i = 0; i < ARRAY_SIZE(func_table); i++) {
                info = &func_table[i];
                add_function_param_key_hook_late(info->name, &set_param_key_user_data,
                                                 info->param, info->key, info);
        }
}

void register_kernel_user_data2(int id)
{
        my_call_id = id;

        if (option_project != PROJ_KERNEL)
                return;
        select_caller_info_hook(set_called, INTERNAL);
}