check_kernel.c

   1 /*
   2  * Copyright (C) 2010 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * This is kernel specific stuff for smatch_extra.
  20  */
  21
  22 #include "scope.h"
  23 #include "smatch.h"
  24 #include "smatch_extra.h"
  25
  26 static int implied_err_cast_return(struct expression *call, void *unused, struct range_list **rl)
  27 {
  28         struct expression *arg;
  29
  30         arg = get_argument_from_call_expr(call->args, 0);
  31         if (!get_implied_rl(arg, rl))
  32                 *rl = alloc_rl(ll_to_sval(-4095), ll_to_sval(-1));
  33         return 1;
  34 }
  35
  36 static void hack_ERR_PTR(struct symbol *sym)
  37 {
  38         struct symbol *arg;
  39         struct smatch_state *estate;
  40         struct range_list *after;
  41         sval_t low_error = {
  42                 .type = &long_ctype,
  43                 .value = -4095,
  44         };
  45         sval_t minus_one = {
  46                 .type = &long_ctype,
  47                 .value = -1,
  48         };
  49         sval_t zero = {
  50                 .type = &long_ctype,
  51                 .value = 0,
  52         };
  53
  54         if (!sym || !sym->ident)
  55                 return;
  56         if (strcmp(sym->ident->name, "ERR_PTR") != 0)
  57                 return;
  58
  59         arg = first_ptr_list((struct ptr_list *)sym->ctype.base_type->arguments);
  60         if (!arg || !arg->ident || strcmp(arg->ident->name, "error") != 0)
  61                 return;
  62
  63         estate = get_state(SMATCH_EXTRA, "error", arg);
  64         if (!estate) {
  65                 after = alloc_rl(low_error, minus_one);
  66         } else {
  67                 after = rl_intersection(estate_rl(estate), alloc_rl(low_error, zero));
  68                 if (rl_equiv(estate_rl(estate), after))
  69                         return;
  70         }
  71         set_state(SMATCH_EXTRA, arg->ident->name, arg, alloc_estate_rl(after));
  72 }
  73
  74 static void match_param_valid_ptr(const char *fn, struct expression *call_expr,
  75                         struct expression *assign_expr, void *_param)
  76 {
  77         int param = PTR_INT(_param);
  78         struct expression *arg;
  79         struct smatch_state *pre_state;
  80         struct smatch_state *end_state;
  81
  82         arg = get_argument_from_call_expr(call_expr->args, param);
  83         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  84         end_state = estate_filter_range(pre_state, ll_to_sval(-4095), ll_to_sval(0));
  85         set_extra_expr_nomod(arg, end_state);
  86 }
  87
  88 static void match_param_err_or_null(const char *fn, struct expression *call_expr,
  89                         struct expression *assign_expr, void *_param)
  90 {
  91         int param = PTR_INT(_param);
  92         struct expression *arg;
  93         struct range_list *rl;
  94         struct smatch_state *pre_state;
  95         struct smatch_state *end_state;
  96
  97         arg = get_argument_from_call_expr(call_expr->args, param);
  98         pre_state = get_state_expr(SMATCH_EXTRA, arg);
  99         rl = alloc_rl(ll_to_sval(-4095), ll_to_sval(0));
 100         rl = rl_intersection(estate_rl(pre_state), rl);
 101         rl = cast_rl(estate_type(pre_state), rl);
 102         end_state = alloc_estate_rl(rl);
 103         set_extra_expr_nomod(arg, end_state);
 104 }
 105
 106 static void match_not_err(const char *fn, struct expression *call_expr,
 107                         struct expression *assign_expr, void *unused)
 108 {
 109         struct expression *arg;
 110         struct smatch_state *pre_state;
 111         struct smatch_state *new_state;
 112
 113         arg = get_argument_from_call_expr(call_expr->args, 0);
 114         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 115         new_state = estate_filter_range(pre_state, sval_type_min(&long_ctype), ll_to_sval(-1));
 116         set_extra_expr_nomod(arg, new_state);
 117 }
 118
 119 static void match_err(const char *fn, struct expression *call_expr,
 120                         struct expression *assign_expr, void *unused)
 121 {
 122         struct expression *arg;
 123         struct smatch_state *pre_state;
 124         struct smatch_state *new_state;
 125
 126         arg = get_argument_from_call_expr(call_expr->args, 0);
 127         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 128         new_state = estate_filter_range(pre_state, sval_type_min(&long_ctype), ll_to_sval(-4096));
 129         new_state = estate_filter_range(new_state, ll_to_sval(0), sval_type_max(&long_ctype));
 130         set_extra_expr_nomod(arg, new_state);
 131 }
 132
 133 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
 134 {
 135         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 136 }
 137
 138 static void match_container_of(struct expression *expr)
 139 {
 140         struct expression *right = expr->right;
 141         char *macro;
 142
 143         /*
 144          * The problem here is that sometimes the container_of() macro is itself
 145          * inside a macro and get_macro() only returns the name of the outside
 146          * macro.
 147          */
 148
 149         /*
 150          * This actually an expression statement assignment but smatch_flow
 151          * pre-mangles it for us so we only get the last chunk:
 152          * sk = (typeof(sk))((char *)__mptr - offsetof(...))
 153          */
 154
 155         macro = get_macro_name(right->pos);
 156         if (!macro)
 157                 return;
 158         if (right->type != EXPR_CAST)
 159                 return;
 160         right = strip_expr(right);
 161         if (right->type != EXPR_BINOP || right->op != '-' ||
 162             right->left->type != EXPR_CAST)
 163                 return;
 164         right = strip_expr(right->left);
 165         if (right->type != EXPR_SYMBOL)
 166                 return;
 167         if (!right->symbol->ident ||
 168             strcmp(right->symbol->ident->name, "__mptr") != 0)
 169                 return;
 170         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 171 }
 172
 173 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
 174 {
 175         struct expression *start_arg;
 176         struct expression *size_arg;
 177         struct symbol *type;
 178         sval_t min, max, tmp;
 179
 180         size_arg = get_argument_from_call_expr(call->args, 1);
 181         /* btw. there isn't a start_arg for find_first_bit() */
 182         start_arg = get_argument_from_call_expr(call->args, 2);
 183
 184         type = get_type(call);
 185         min = sval_type_val(type, 0);
 186         max = sval_type_val(type, sizeof(long long) * 8);
 187
 188         if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
 189                 max = tmp;
 190         if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
 191                 min = tmp;
 192         if (sval_cmp(min, max) > 0)
 193                 max = min;
 194         min = sval_cast(type, min);
 195         max = sval_cast(type, max);
 196         *rl = alloc_rl(min, max);
 197         return 1;
 198 }
 199
 200 static void find_module_init_exit(struct symbol_list *sym_list)
 201 {
 202         struct symbol *sym;
 203         struct symbol *fn;
 204         struct statement *stmt;
 205         char *name;
 206         int init;
 207         int count;
 208
 209         /*
 210          * This is more complicated because Sparse ignores the "alias"
 211          * attribute.  I search backwards because module_init() is normally at
 212          * the end of the file.
 213          */
 214         count = 0;
 215         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 216                 if (sym->type != SYM_NODE)
 217                         continue;
 218                 if (!(sym->ctype.modifiers & MOD_STATIC))
 219                         continue;
 220                 fn = get_base_type(sym);
 221                 if (!fn)
 222                         continue;
 223                 if (fn->type != SYM_FN)
 224                         continue;
 225                 if (!sym->ident)
 226                         continue;
 227                 if (!fn->inline_stmt)
 228                         continue;
 229                 if (strcmp(sym->ident->name, "__inittest") == 0)
 230                         init = 1;
 231                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 232                         init = 0;
 233                 else
 234                         continue;
 235
 236                 count++;
 237
 238                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 239                 if (!stmt || stmt->type != STMT_RETURN)
 240                         continue;
 241                 name = expr_to_var(stmt->ret_value);
 242                 if (!name)
 243                         continue;
 244                 if (init)
 245                         sql_insert_function_ptr(name, "(struct module)->init");
 246                 else
 247                         sql_insert_function_ptr(name, "(struct module)->exit");
 248                 free_string(name);
 249                 if (count >= 2)
 250                         return;
 251         } END_FOR_EACH_PTR_REVERSE(sym);
 252 }
 253
 254 static void match_end_file(struct symbol_list *sym_list)
 255 {
 256         struct symbol *sym;
 257
 258         /* find the last static symbol in the file */
 259         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 260                 if (!(sym->ctype.modifiers & MOD_STATIC))
 261                         continue;
 262                 if (!sym->scope)
 263                         continue;
 264                 find_module_init_exit(sym->scope->symbols);
 265                 return;
 266         } END_FOR_EACH_PTR_REVERSE(sym);
 267 }
 268
 269 static struct expression *get_val_expr(struct expression *expr)
 270 {
 271         struct symbol *sym, *val;
 272
 273         if (expr->type != EXPR_DEREF)
 274                 return NULL;
 275         expr = expr->deref;
 276         if (expr->type != EXPR_SYMBOL)
 277                 return NULL;
 278         if (strcmp(expr->symbol_name->name, "__u") != 0)
 279                 return NULL;
 280         sym = get_base_type(expr->symbol);
 281         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 282         if (!val || strcmp(val->ident->name, "__val") != 0)
 283                 return NULL;
 284         return member_expression(expr, '.', val->ident);
 285 }
 286
 287 static void match__write_once_size(const char *fn, struct expression *call,
 288                                void *unused)
 289 {
 290         struct expression *dest, *data, *assign;
 291         struct range_list *rl;
 292
 293         dest = get_argument_from_call_expr(call->args, 0);
 294         if (dest->type != EXPR_PREOP || dest->op != '&')
 295                 return;
 296         dest = strip_expr(dest->unop);
 297
 298         data = get_argument_from_call_expr(call->args, 1);
 299         data = get_val_expr(data);
 300         if (!data)
 301                 return;
 302         get_absolute_rl(data, &rl);
 303         assign = assign_expression(dest, data);
 304
 305         __in_fake_assign++;
 306         __split_expr(assign);
 307         __in_fake_assign--;
 308 }
 309
 310 void check_kernel(int id)
 311 {
 312         if (option_project != PROJ_KERNEL)
 313                 return;
 314
 315         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 316         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 317         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 318         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 319         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 320         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 321         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 322         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 323         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 324
 325         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 326         add_hook(match_container_of, ASSIGNMENT_HOOK);
 327
 328         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 329         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 330         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 331         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 332
 333         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 334         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 335
 336         if (option_info)
 337                 add_hook(match_end_file, END_FILE_HOOK);
 338 }