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 int match_fls(struct expression *call, void *unused, struct range_list **rl)
 201 {
 202         struct expression *arg;
 203         struct range_list *arg_rl;
 204         sval_t zero = {};
 205         sval_t start = {
 206                 .type = &int_ctype,
 207                 .value = 0,
 208         };
 209         sval_t end = {
 210                 .type = &int_ctype,
 211                 .value = 32,
 212         };
 213         sval_t sval;
 214
 215         arg = get_argument_from_call_expr(call->args, 0);
 216         if (!get_implied_rl(arg, &arg_rl))
 217                 return 0;
 218         if (rl_to_sval(arg_rl, &sval)) {
 219                 int i;
 220
 221                 for (i = 63; i >= 0; i--) {
 222                         if (sval.uvalue & 1ULL << i)
 223                                 break;
 224                 }
 225                 sval.value = i + 1;
 226                 *rl = alloc_rl(sval, sval);
 227                 return 1;
 228         }
 229         zero.type = rl_type(arg_rl);
 230         if (!rl_has_sval(arg_rl, zero))
 231                 start.value = 1;
 232         *rl = alloc_rl(start, end);
 233         return 1;
 234 }
 235
 236
 237
 238 static void find_module_init_exit(struct symbol_list *sym_list)
 239 {
 240         struct symbol *sym;
 241         struct symbol *fn;
 242         struct statement *stmt;
 243         char *name;
 244         int init;
 245         int count;
 246
 247         /*
 248          * This is more complicated because Sparse ignores the "alias"
 249          * attribute.  I search backwards because module_init() is normally at
 250          * the end of the file.
 251          */
 252         count = 0;
 253         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 254                 if (sym->type != SYM_NODE)
 255                         continue;
 256                 if (!(sym->ctype.modifiers & MOD_STATIC))
 257                         continue;
 258                 fn = get_base_type(sym);
 259                 if (!fn)
 260                         continue;
 261                 if (fn->type != SYM_FN)
 262                         continue;
 263                 if (!sym->ident)
 264                         continue;
 265                 if (!fn->inline_stmt)
 266                         continue;
 267                 if (strcmp(sym->ident->name, "__inittest") == 0)
 268                         init = 1;
 269                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 270                         init = 0;
 271                 else
 272                         continue;
 273
 274                 count++;
 275
 276                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 277                 if (!stmt || stmt->type != STMT_RETURN)
 278                         continue;
 279                 name = expr_to_var(stmt->ret_value);
 280                 if (!name)
 281                         continue;
 282                 if (init)
 283                         sql_insert_function_ptr(name, "(struct module)->init");
 284                 else
 285                         sql_insert_function_ptr(name, "(struct module)->exit");
 286                 free_string(name);
 287                 if (count >= 2)
 288                         return;
 289         } END_FOR_EACH_PTR_REVERSE(sym);
 290 }
 291
 292 static void match_end_file(struct symbol_list *sym_list)
 293 {
 294         struct symbol *sym;
 295
 296         /* find the last static symbol in the file */
 297         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 298                 if (!(sym->ctype.modifiers & MOD_STATIC))
 299                         continue;
 300                 if (!sym->scope)
 301                         continue;
 302                 find_module_init_exit(sym->scope->symbols);
 303                 return;
 304         } END_FOR_EACH_PTR_REVERSE(sym);
 305 }
 306
 307 static struct expression *get_val_expr(struct expression *expr)
 308 {
 309         struct symbol *sym, *val;
 310
 311         if (expr->type != EXPR_DEREF)
 312                 return NULL;
 313         expr = expr->deref;
 314         if (expr->type != EXPR_SYMBOL)
 315                 return NULL;
 316         if (strcmp(expr->symbol_name->name, "__u") != 0)
 317                 return NULL;
 318         sym = get_base_type(expr->symbol);
 319         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 320         if (!val || strcmp(val->ident->name, "__val") != 0)
 321                 return NULL;
 322         return member_expression(expr, '.', val->ident);
 323 }
 324
 325 static void match__write_once_size(const char *fn, struct expression *call,
 326                                void *unused)
 327 {
 328         struct expression *dest, *data, *assign;
 329         struct range_list *rl;
 330
 331         dest = get_argument_from_call_expr(call->args, 0);
 332         if (dest->type != EXPR_PREOP || dest->op != '&')
 333                 return;
 334         dest = strip_expr(dest->unop);
 335
 336         data = get_argument_from_call_expr(call->args, 1);
 337         data = get_val_expr(data);
 338         if (!data)
 339                 return;
 340         get_absolute_rl(data, &rl);
 341         assign = assign_expression(dest, '=', data);
 342
 343         __in_fake_assign++;
 344         __split_expr(assign);
 345         __in_fake_assign--;
 346 }
 347
 348 static void match__read_once_size(const char *fn, struct expression *call,
 349                                void *unused)
 350 {
 351         struct expression *dest, *data, *assign;
 352         struct symbol *type, *val_sym;
 353
 354         /*
 355          * We want to change:
 356          *      __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
 357          * into a fake assignment:
 358          *      __u.val = x;
 359          *
 360          */
 361
 362         data = get_argument_from_call_expr(call->args, 0);
 363         if (data->type != EXPR_PREOP || data->op != '&')
 364                 return;
 365         data = strip_parens(data->unop);
 366
 367         dest = get_argument_from_call_expr(call->args, 1);
 368         if (dest->type != EXPR_DEREF || dest->op != '.')
 369                 return;
 370         if (!dest->member || strcmp(dest->member->name, "__c") != 0)
 371                 return;
 372         dest = dest->deref;
 373         type = get_type(dest);
 374         if (!type)
 375                 return;
 376         val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
 377         dest = member_expression(dest, '.', val_sym->ident);
 378
 379         assign = assign_expression(dest, '=', data);
 380         __in_fake_assign++;
 381         __split_expr(assign);
 382         __in_fake_assign--;
 383 }
 384
 385 void check_kernel(int id)
 386 {
 387         if (option_project != PROJ_KERNEL)
 388                 return;
 389
 390         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 391         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 392         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 393         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 394         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 395         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 396         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 397         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 398         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 399
 400         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 401         add_hook(match_container_of, ASSIGNMENT_HOOK);
 402
 403         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 404         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 405         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 406         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 407
 408         add_implied_return_hook("fls", &match_fls, NULL);
 409         add_implied_return_hook("fls64", &match_fls, NULL);
 410
 411         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 412         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 413
 414         add_function_hook("__read_once_size", &match__read_once_size, NULL);
 415         add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
 416
 417         if (option_info)
 418                 add_hook(match_end_file, END_FILE_HOOK);
 419 }