/*
 * 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;

STATE(called);
static bool func_gets_user_data;

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",
};

static const char *returns_pointer_to_user_data[] = {
        "nlmsg_data", "nla_data", "memdup_user", "kmap_atomic", "skb_network_header",
};

static void set_points_to_user_data(struct expression *expr);

static struct stree *start_states;
static struct stree_stack *saved_stack;
static void save_start_states(struct statement *stmt)
{
        start_states = clone_stree(__get_cur_stree());
}

static void free_start_states(void)
{
        free_stree(&start_states);
}

static void match_save_states(struct expression *expr)
{
        push_stree(&saved_stack, start_states);
        start_states = NULL;
}

static void match_restore_states(struct expression *expr)
{
        free_stree(&start_states);
        start_states = pop_stree(&saved_stack);
}

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

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

        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 == '%') {
                if (is_capped(expr->left) || is_capped(expr->right))
                        return true;
                if (user_rl_capped(expr->left) || user_rl_capped(expr->right))
                        return true;
                return false;
        }

        if (user_rl_capped(expr->left) &&
            user_rl_capped(expr->right))
                return true;
        return false;
}

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))
                return false;  /* uncapped user data */

        return true;  /* not actually 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_state_expr(my_id, edge_member, alloc_estate_whole(type));
        } END_FOR_EACH_PTR(tmp);
}

static void tag_struct_members(struct symbol *type, struct expression *expr)
{
        struct symbol *tmp;
        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) {
                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;

                member = member_expression(expr, op, tmp->ident);
                set_state_expr(my_id, member, alloc_estate_whole(get_type(member)));

                if (type->type == SYM_ARRAY)
                        set_points_to_user_data(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_state_expr(my_id, expr, alloc_estate_whole(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_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&ulong_ctype));
                return;
        }
        if (type->type == SYM_BASETYPE)
                tag_base_type(expr);
        if (type->type == SYM_STRUCT || type->type == SYM_UNION) {
                if (expr->type != EXPR_PREOP || expr->op != '&')
                        expr = deref_expression(expr);
                else
                        set_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&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;

        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 int ends_in_n(struct expression *expr)
{
        struct string *str;

        if (!expr)
                return 0;
        if (expr->type != EXPR_STRING || !expr->string)
                return 0;

        str = expr->string;
        if (str->length < 3)
                return 0;

        if (str->data[str->length - 3] == '%' &&
            str->data[str->length - 2] == 'n')
                return 1;
        return 0;
}

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

        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;

        last = ptr_list_size((struct ptr_list *)expr->args) - 1;

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

static int is_skb_data(struct expression *expr)
{
        struct symbol *sym;

        if (!expr)
                return 0;

        if (expr->type == EXPR_BINOP && expr->op == '+')
                return is_skb_data(expr->left);

        expr = strip_expr(expr);
        if (!expr)
                return 0;
        if (expr->type != EXPR_DEREF || expr->op != '.')
                return 0;

        if (!expr->member)
                return 0;
        if (strcmp(expr->member->name, "data") != 0)
                return 0;

        sym = expr_to_sym(expr->deref);
        if (!sym)
                return 0;
        sym = get_real_base_type(sym);
        if (!sym || sym->type != SYM_PTR)
                return 0;
        sym = get_real_base_type(sym);
        if (!sym || sym->type != SYM_STRUCT || !sym->ident)
                return 0;
        if (strcmp(sym->ident->name, "sk_buff") != 0)
                return 0;

        return 1;
}

static bool is_points_to_user_data_fn(struct expression *expr)
{
        int i;

        expr = strip_expr(expr);
        if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
            !expr->fn->symbol)
                return false;
        expr = expr->fn;
        for (i = 0; i < ARRAY_SIZE(returns_pointer_to_user_data); i++) {
                if (sym_name_is(returns_pointer_to_user_data[i], expr))
                        return true;
        }
        return false;
}

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 || !expr->fn->symbol_name->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;
}

int points_to_user_data(struct expression *expr)
{
        struct smatch_state *state;
        struct range_list *rl;
        char buf[256];
        struct symbol *sym;
        char *name;
        int ret = 0;

        expr = strip_expr(expr);
        if (!expr)
                return 0;
        if (is_skb_data(expr))
                return 1;
        if (is_points_to_user_data_fn(expr))
                return 1;
        if (get_rl_from_function(expr, &rl))
                return 1;

        if (expr->type == EXPR_BINOP && expr->op == '+') {
                if (points_to_user_data(expr->left))
                        return 1;
                if (points_to_user_data(expr->right))
                        return 1;
                return 0;
        }

        name = expr_to_var_sym(expr, &sym);
        if (!name || !sym)
                goto free;
        snprintf(buf, sizeof(buf), "*%s", name);
        state = __get_state(my_id, buf, sym);
        if (state && estate_rl(state))
                ret = 1;
free:
        free_string(name);
        return ret;
}

static void set_points_to_user_data(struct expression *expr)
{
        char *name;
        struct symbol *sym;
        char buf[256];
        struct symbol *type;

        name = expr_to_var_sym(expr, &sym);
        if (!name || !sym)
                goto free;
        snprintf(buf, sizeof(buf), "*%s", name);
        type = get_type(expr);
        if (type && type->type == SYM_PTR)
                type = get_real_base_type(type);
        if (!type || type->type != SYM_BASETYPE)
                type = &llong_ctype;
        set_state(my_id, buf, sym, alloc_estate_whole(type));
free:
        free_string(name);
}

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_struct_assignment(struct expression *expr)
{
        struct expression *right;
        struct symbol *left_type, *right_type;

        left_type = get_type(expr->left);
        if (!left_type || left_type->type != SYM_PTR)
                return 0;
        left_type = get_real_base_type(left_type);
        if (!left_type)
                return 0;
        if (left_type->type != SYM_STRUCT &&
            left_type->type != SYM_UNION)
                return 0;

        /*
         * Ignore struct to struct assignments because for those we look at the
         * individual members.
         */
        right = strip_expr(expr->right);
        right_type = get_type(right);
        if (!right_type || right_type->type != SYM_PTR)
                return 0;

        /* If we are assigning struct members then normally that is handled
         * by fake assignments, however if we cast one struct to a different
         * of struct then we handle that here.
         */
        right_type = get_real_base_type(right_type);
        if (right_type == left_type)
                return 0;

        if (!points_to_user_data(right))
                return 0;

        tag_as_user_data(expr->left);
        return 1;
}

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_state_expr(my_id, expr->left, alloc_estate_whole(get_type(expr->left)));
        ret = 1;
free:
        free_string(name);
        return ret;
}

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 (user_rl_capped(binop_expr))
                        estate_set_capped(state);
                if (user_rl_treat_untagged(expr->left))
                        estate_set_treat_untagged(state);
                set_state_expr(my_id, expr->left, state);
                return true;
        }
        return false;
}

static void match_assign(struct expression *expr)
{
        struct range_list *rl;
        static struct expression *handled;
        struct smatch_state *state;
        struct expression *faked;

        faked = get_faked_expression();
        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)) {
                handled = expr;
                set_points_to_user_data(expr->left);
        }
        if (handle_struct_assignment(expr))
                return;

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

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

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

        rl = cast_rl(get_type(expr->left), rl);
        state = alloc_estate_rl(rl);

        if (user_rl_capped(expr->right))
                estate_set_capped(state);
        if (user_rl_treat_untagged(expr->right))
                estate_set_treat_untagged(state);
        set_state_expr(my_id, expr->left, state);

        return;

clear_old_state:
        if (get_state_expr(my_id, expr->left))
                set_state_expr(my_id, 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 struct range_list *strip_negatives(struct range_list *rl)
{
        sval_t min = rl_min(rl);
        sval_t minus_one;
        sval_t over;
        sval_t max = sval_type_max(rl_type(rl));

        minus_one.type = rl_type(rl);
        minus_one.value = -1;
        over.type = rl_type(rl);
        over.value = INT_MAX + 1ULL;

        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 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_user_assign_function(const char *fn, struct expression *expr, void *unused)
{
        tag_as_user_data(expr->left);
        set_points_to_user_data(expr->left);
}

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;
}

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

        FOR_EACH_PTR(call->args, arg) {
                sym = expr_to_sym(arg);
                if (!sym)
                        continue;
                if (has_user_data(sym))
                        return 1;
        } END_FOR_EACH_PTR(arg);

        return 0;
}

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 int user_data_flag;
static int no_user_data_flag;
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 == '&') {
                no_user_data_flag = 1;
                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)
                                no_user_data_flag = 1;
                }

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

                if (!get_state_expr(my_id, array)) {
                        no_user_data_flag = 1;
                        return NULL;
                }
        }

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

        return NULL;
found:
        user_data_flag = 1;
        absolute_rl = var_to_absolute_rl(expr);
        return clone_rl(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)
{
        if (is_ptr_subtract(expr))
                return 0;

        user_data_flag = 0;
        no_user_data_flag = 0;
        custom_get_absolute_rl(expr, &var_user_rl, rl);
        if (!user_data_flag || no_user_data_flag)
                *rl = NULL;

        return !!*rl;
}

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

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

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

        state = get_state(my_id, name, sym);
        if (state && estate_rl(state)) {
                *rl = estate_rl(state);
                return 1;
        }
        return 0;
}

static char *get_user_rl_str(struct expression *expr, struct symbol *type)
{
        struct range_list *rl;
        static char buf[64];

        if (!get_user_rl(expr, &rl))
                return NULL;
        rl = cast_rl(type, rl);
        snprintf(buf, sizeof(buf), "%s%s%s",
                 show_rl(rl),
                 user_rl_capped(expr) ? "[c]" : "",
                 user_rl_treat_untagged(expr) ? "[u]" : "");
        return buf;
}

static void match_call_info(struct expression *expr)
{
        struct expression *arg;
        struct symbol *type;
        char *str;
        int i;

        i = -1;
        FOR_EACH_PTR(expr->args, arg) {
                i++;
                type = get_arg_type(expr->fn, i);
                str = get_user_rl_str(arg, type);
                if (!str)
                        continue;

                sql_insert_caller_info(expr, USER_DATA, i, "$", str);
        } END_FOR_EACH_PTR(arg);
}

static void struct_member_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];

        /*
         * 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 (type && type_bits(type) < type_bits(&ptr_ctype))
                return;

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

        if (strcmp(printed_name, "*$") == 0 &&
            is_struct_ptr(sm->sym))
                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;

        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 range_list *rl = NULL;
        struct smatch_state *state;
        struct expression *expr;
        struct symbol *type;
        char fullname[256];
        char *key_orig = key;
        bool add_star = false;

        if (strcmp(key, "**$") == 0) {
                snprintf(fullname, sizeof(fullname), "**%s", name);
        } else {
                if (key[0] == '*') {
                        add_star = true;
                        key++;
                }

                snprintf(fullname, 256, "%s%s%s", add_star ? "*" : "", name, key + 1);
        }

        expr = symbol_expression(sym);
        type = get_member_type_from_key(expr, key_orig);

        /*
         * Say this function takes a struct ponter but the caller passes
         * this_function(skb->data).  We have two options, we could pass *$
         * as user data or we could pass foo->bar, foo->baz as user data.
         * The second option is easier to implement so we do that.
         *
         */
        if (strcmp(key_orig, "*$") == 0) {
                struct symbol *tmp = type;

                while (tmp && tmp->type == SYM_PTR)
                        tmp = get_real_base_type(tmp);

                if (tmp && (tmp->type == SYM_STRUCT || tmp->type == SYM_UNION)) {
                        tag_as_user_data(symbol_expression(sym));
                        return;
                }
        }

        str_to_rl(type, value, &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);
}

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

        if (strcmp(key, "$") != 0)
                return;

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

        set_state(my_id, buf, NULL, alloc_estate_rl(rl));
}

static void set_to_user_data(struct expression *expr, char *key, char *value)
{
        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);
        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) {
                        store_user_data_return(expr, key, value);
                        return;
                }
                set_to_user_data(expr->left, key, value);
                return;
        }

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

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);
                        return;
                }
                if (strcmp(key, "*$") == 0) {
                        set_points_to_user_data(expr->left);
                        tag_as_user_data(expr->left);
                } else {
                        set_to_user_data(expr->left, key, value);
                }
                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);
}

static void param_set_to_user_data(int return_id, char *return_ranges, struct expression *expr)
{
        struct sm_state *sm;
        struct smatch_state *start_state;
        struct range_list *rl;
        int param;
        char *return_str;
        const char *param_name;
        struct symbol *ret_sym;
        bool return_found = false;
        bool pointed_at_found = false;
        char buf[64];

        expr = strip_expr(expr);
        return_str = expr_to_str(expr);
        ret_sym = expr_to_sym(expr);

        FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
                param = get_param_num_from_sym(sm->sym);
                if (param < 0)
                        continue;

                if (!param_was_set_var_sym(sm->name, sm->sym))
                        continue;

                /* The logic here was that if we were passed in a user data then
                 * we don't record that.  It's like the difference between
                 * param_filter and param_set.  When I think about it, I'm not
                 * sure it actually works.  It's probably harmless because we
                 * checked earlier that we're not returning a parameter...
                 * Let's mark this as a TODO.
                 */
                start_state = get_state_stree(start_states, my_id, sm->name, sm->sym);
                if (start_state && rl_equiv(estate_rl(sm->state), estate_rl(start_state)))
                        continue;

                param_name = get_param_name(sm);
                if (!param_name)
                        continue;
                if (strcmp(param_name, "$") == 0)  /* The -1 param is handled after the loop */
                        continue;

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

        /* This if for "return foo;" where "foo->bar" is user data. */
        FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
                if (!ret_sym)
                        break;
                if (ret_sym != sm->sym)
                        continue;

                param_name = state_name_to_param_name(sm->name, return_str);
                if (!param_name)
                        continue;
                if (strcmp(param_name, "$") == 0)
                        return_found = true;
                if (strcmp(param_name, "*$") == 0)
                        pointed_at_found = true;
                snprintf(buf, sizeof(buf), "%s%s%s",
                         show_rl(estate_rl(sm->state)),
                         estate_capped(sm->state) ? "[c]" : "",
                         estate_treat_untagged(sm->state) ? "[u]" : "");
                sql_insert_return_states(return_id, return_ranges,
                                         func_gets_user_data ? USER_DATA_SET : USER_DATA,
                                         -1, param_name, buf);
        } END_FOR_EACH_SM(sm);

        /* This if for "return ntohl(foo);" */
        if (!return_found && get_user_rl(expr, &rl)) {
                snprintf(buf, sizeof(buf), "%s%s%s",
                         show_rl(rl),
                         user_rl_capped(expr) ? "[c]" : "",
                         user_rl_treat_untagged(expr) ? "[u]" : "");
                sql_insert_return_states(return_id, return_ranges,
                                         func_gets_user_data ? USER_DATA_SET : USER_DATA,
                                         -1, "$", buf);
        }

        /*
         * This is to handle things like return skb->data where we don't set a
         * state for that.
         */
        if (!pointed_at_found && points_to_user_data(expr)) {
                sql_insert_return_states(return_id, return_ranges,
                                         (is_skb_data(expr) || func_gets_user_data) ?
                                         USER_DATA_SET : USER_DATA,
                                         -1, "*$", "s64min-s64max");
        }

        free_string(return_str);
}

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

        name = return_state_to_var_sym(expr, param, key, &sym);
        if (!name || !sym)
                goto free;

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

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

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

static struct int_stack *gets_data_stack;
static void match_function_def(struct symbol *sym)
{
        func_gets_user_data = false;
}

static void match_inline_start(struct expression *expr)
{
        push_int(&gets_data_stack, func_gets_user_data);
}

static void match_inline_end(struct expression *expr)
{
        func_gets_user_data = pop_int(&gets_data_stack);
}

void register_kernel_user_data(int id)
{
        int i;

        my_id = id;

        if (option_project != PROJ_KERNEL)
                return;

        set_dynamic_states(my_id);

        add_hook(&match_function_def, FUNC_DEF_HOOK);
        add_hook(&match_inline_start, INLINE_FN_START);
        add_hook(&match_inline_end, INLINE_FN_END);

        add_hook(&save_start_states, AFTER_DEF_HOOK);
        add_hook(&free_start_states, AFTER_FUNC_HOOK);
        add_hook(&match_save_states, INLINE_FN_START);
        add_hook(&match_restore_states, INLINE_FN_END);

        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(kstr_funcs[i], &match_user_copy, INT_PTR(2));
        add_function_hook("usb_control_msg", &match_user_copy, INT_PTR(6));

        for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
                add_function_assign_hook(returns_user_data[i], &match_user_assign_function, NULL);
                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_hook(&match_call_info, FUNCTION_CALL_HOOK);
        add_member_info_callback(my_id, struct_member_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_states_hook(CAPPED_DATA, &returns_param_capped);
        add_split_return_callback(&param_set_to_user_data);
}

void register_kernel_user_data2(int id)
{
        my_call_id = id;

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