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 sval_t err_ptr_min = {
  27         .type = &ptr_ctype,
  28         .value = -4095,
  29 };
  30 static sval_t err_ptr_max = {
  31         .type = &ptr_ctype,
  32         .value = -1,
  33 };
  34 static sval_t null_ptr = {
  35         .type = &ptr_ctype,
  36         .value = 0,
  37 };
  38
  39 static int implied_err_cast_return(struct expression *call, void *unused, struct range_list **rl)
  40 {
  41         struct expression *arg;
  42
  43         arg = get_argument_from_call_expr(call->args, 0);
  44         if (!get_implied_rl(arg, rl))
  45                 *rl = alloc_rl(err_ptr_min, err_ptr_max);
  46
  47         *rl = cast_rl(get_type(call), *rl);
  48         return 1;
  49 }
  50
  51 static void hack_ERR_PTR(struct symbol *sym)
  52 {
  53         struct symbol *arg;
  54         struct smatch_state *estate;
  55         struct range_list *after;
  56         sval_t low_error = {
  57                 .type = &long_ctype,
  58                 .value = -4095,
  59         };
  60         sval_t minus_one = {
  61                 .type = &long_ctype,
  62                 .value = -1,
  63         };
  64         sval_t zero = {
  65                 .type = &long_ctype,
  66                 .value = 0,
  67         };
  68
  69         if (!sym || !sym->ident)
  70                 return;
  71         if (strcmp(sym->ident->name, "ERR_PTR") != 0)
  72                 return;
  73
  74         arg = first_ptr_list((struct ptr_list *)sym->ctype.base_type->arguments);
  75         if (!arg || !arg->ident)
  76                 return;
  77
  78         estate = get_state(SMATCH_EXTRA, arg->ident->name, arg);
  79         if (!estate) {
  80                 after = alloc_rl(low_error, minus_one);
  81         } else {
  82                 after = rl_intersection(estate_rl(estate), alloc_rl(low_error, zero));
  83                 if (rl_equiv(estate_rl(estate), after))
  84                         return;
  85         }
  86         set_state(SMATCH_EXTRA, arg->ident->name, arg, alloc_estate_rl(after));
  87 }
  88
  89 static void match_param_valid_ptr(const char *fn, struct expression *call_expr,
  90                         struct expression *assign_expr, void *_param)
  91 {
  92         int param = PTR_INT(_param);
  93         struct expression *arg;
  94         struct smatch_state *pre_state;
  95         struct smatch_state *end_state;
  96         struct range_list *rl;
  97
  98         arg = get_argument_from_call_expr(call_expr->args, param);
  99         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 100         if (estate_rl(pre_state)) {
 101                 rl = estate_rl(pre_state);
 102                 rl = remove_range(rl, null_ptr, null_ptr);
 103                 rl = remove_range(rl, err_ptr_min, err_ptr_max);
 104         } else {
 105                 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 106         }
 107         end_state = alloc_estate_rl(rl);
 108         set_extra_expr_nomod(arg, end_state);
 109 }
 110
 111 static void match_param_err_or_null(const char *fn, struct expression *call_expr,
 112                         struct expression *assign_expr, void *_param)
 113 {
 114         int param = PTR_INT(_param);
 115         struct expression *arg;
 116         struct range_list *pre, *rl;
 117         struct smatch_state *pre_state;
 118         struct smatch_state *end_state;
 119
 120         arg = get_argument_from_call_expr(call_expr->args, param);
 121         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 122         if (pre_state)
 123                 pre = estate_rl(pre_state);
 124         else
 125                 pre = alloc_whole_rl(&ptr_ctype);
 126         call_results_to_rl(call_expr, &ptr_ctype, "0,(-4095)-(-1)", &rl);
 127         rl = rl_intersection(pre, rl);
 128         rl = cast_rl(get_type(arg), rl);
 129         end_state = alloc_estate_rl(rl);
 130         set_extra_expr_nomod(arg, end_state);
 131 }
 132
 133 static void match_not_err(const char *fn, struct expression *call_expr,
 134                         struct expression *assign_expr, void *unused)
 135 {
 136         struct expression *arg;
 137         struct smatch_state *pre_state;
 138         struct range_list *rl;
 139
 140         arg = get_argument_from_call_expr(call_expr->args, 0);
 141         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 142         if (pre_state) {
 143                 rl = estate_rl(pre_state);
 144                 rl = remove_range(rl, err_ptr_min, err_ptr_max);
 145         } else {
 146                 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 147         }
 148         rl = cast_rl(get_type(arg), rl);
 149         /* These are implied.  But implications don't work for empty states. */
 150         if (pre_state && rl)
 151                 return;
 152         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 153 }
 154
 155 static void match_err(const char *fn, struct expression *call_expr,
 156                         struct expression *assign_expr, void *unused)
 157 {
 158         struct expression *arg;
 159         struct smatch_state *pre_state;
 160         struct range_list *rl;
 161
 162         arg = get_argument_from_call_expr(call_expr->args, 0);
 163         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 164         rl = estate_rl(pre_state);
 165         if (!rl)
 166                 rl = alloc_rl(err_ptr_min, err_ptr_max);
 167         rl = rl_intersection(rl, alloc_rl(err_ptr_min, err_ptr_max));
 168         rl = cast_rl(get_type(arg), rl);
 169         if (pre_state && rl) {
 170                 /*
 171                  * Ideally this would all be handled by smatch_implied.c
 172                  * but it doesn't work very well for impossible paths.
 173                  *
 174                  */
 175                 return;
 176         }
 177         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 178 }
 179
 180 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
 181 {
 182         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 183 }
 184
 185 static void match_container_of(struct expression *expr)
 186 {
 187         struct expression *right = expr->right;
 188         char *macro;
 189
 190         /*
 191          * The problem here is that sometimes the container_of() macro is itself
 192          * inside a macro and get_macro() only returns the name of the outside
 193          * macro.
 194          */
 195
 196         /*
 197          * This actually an expression statement assignment but smatch_flow
 198          * pre-mangles it for us so we only get the last chunk:
 199          * sk = (typeof(sk))((char *)__mptr - offsetof(...))
 200          */
 201
 202         macro = get_macro_name(right->pos);
 203         if (!macro)
 204                 return;
 205         if (right->type != EXPR_CAST)
 206                 return;
 207         right = strip_expr(right);
 208         if (right->type != EXPR_BINOP || right->op != '-' ||
 209             right->left->type != EXPR_CAST)
 210                 return;
 211         right = strip_expr(right->left);
 212         if (right->type != EXPR_SYMBOL)
 213                 return;
 214         if (!right->symbol->ident ||
 215             strcmp(right->symbol->ident->name, "__mptr") != 0)
 216                 return;
 217         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 218 }
 219
 220 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
 221 {
 222         struct expression *start_arg;
 223         struct expression *size_arg;
 224         struct symbol *type;
 225         sval_t min, max, tmp;
 226
 227         size_arg = get_argument_from_call_expr(call->args, 1);
 228         /* btw. there isn't a start_arg for find_first_bit() */
 229         start_arg = get_argument_from_call_expr(call->args, 2);
 230
 231         type = get_type(call);
 232         min = sval_type_val(type, 0);
 233         max = sval_type_val(type, sizeof(long long) * 8);
 234
 235         if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
 236                 max = tmp;
 237         if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
 238                 min = tmp;
 239         if (sval_cmp(min, max) > 0)
 240                 max = min;
 241         min = sval_cast(type, min);
 242         max = sval_cast(type, max);
 243         *rl = alloc_rl(min, max);
 244         return 1;
 245 }
 246
 247 static int match_fls(struct expression *call, void *unused, struct range_list **rl)
 248 {
 249         struct expression *arg;
 250         struct range_list *arg_rl;
 251         sval_t zero = {};
 252         sval_t start = {
 253                 .type = &int_ctype,
 254                 .value = 0,
 255         };
 256         sval_t end = {
 257                 .type = &int_ctype,
 258                 .value = 32,
 259         };
 260         sval_t sval;
 261
 262         arg = get_argument_from_call_expr(call->args, 0);
 263         if (!get_implied_rl(arg, &arg_rl))
 264                 return 0;
 265         if (rl_to_sval(arg_rl, &sval)) {
 266                 int i;
 267
 268                 for (i = 63; i >= 0; i--) {
 269                         if (sval.uvalue & 1ULL << i)
 270                                 break;
 271                 }
 272                 sval.value = i + 1;
 273                 *rl = alloc_rl(sval, sval);
 274                 return 1;
 275         }
 276         zero.type = rl_type(arg_rl);
 277         if (!rl_has_sval(arg_rl, zero))
 278                 start.value = 1;
 279         *rl = alloc_rl(start, end);
 280         return 1;
 281 }
 282
 283 static void find_module_init_exit(struct symbol_list *sym_list)
 284 {
 285         struct symbol *sym;
 286         struct symbol *fn;
 287         struct statement *stmt;
 288         char *name;
 289         int init;
 290         int count;
 291
 292         /*
 293          * This is more complicated because Sparse ignores the "alias"
 294          * attribute.  I search backwards because module_init() is normally at
 295          * the end of the file.
 296          */
 297         count = 0;
 298         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 299                 if (sym->type != SYM_NODE)
 300                         continue;
 301                 if (!(sym->ctype.modifiers & MOD_STATIC))
 302                         continue;
 303                 fn = get_base_type(sym);
 304                 if (!fn)
 305                         continue;
 306                 if (fn->type != SYM_FN)
 307                         continue;
 308                 if (!sym->ident)
 309                         continue;
 310                 if (!fn->inline_stmt)
 311                         continue;
 312                 if (strcmp(sym->ident->name, "__inittest") == 0)
 313                         init = 1;
 314                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 315                         init = 0;
 316                 else
 317                         continue;
 318
 319                 count++;
 320
 321                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 322                 if (!stmt || stmt->type != STMT_RETURN)
 323                         continue;
 324                 name = expr_to_var(stmt->ret_value);
 325                 if (!name)
 326                         continue;
 327                 if (init)
 328                         sql_insert_function_ptr(name, "(struct module)->init");
 329                 else
 330                         sql_insert_function_ptr(name, "(struct module)->exit");
 331                 free_string(name);
 332                 if (count >= 2)
 333                         return;
 334         } END_FOR_EACH_PTR_REVERSE(sym);
 335 }
 336
 337 static void match_end_file(struct symbol_list *sym_list)
 338 {
 339         struct symbol *sym;
 340
 341         /* find the last static symbol in the file */
 342         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 343                 if (!(sym->ctype.modifiers & MOD_STATIC))
 344                         continue;
 345                 if (!sym->scope)
 346                         continue;
 347                 find_module_init_exit(sym->scope->symbols);
 348                 return;
 349         } END_FOR_EACH_PTR_REVERSE(sym);
 350 }
 351
 352 static struct expression *get_val_expr(struct expression *expr)
 353 {
 354         struct symbol *sym, *val;
 355
 356         if (expr->type != EXPR_DEREF)
 357                 return NULL;
 358         expr = expr->deref;
 359         if (expr->type != EXPR_SYMBOL)
 360                 return NULL;
 361         if (strcmp(expr->symbol_name->name, "__u") != 0)
 362                 return NULL;
 363         sym = get_base_type(expr->symbol);
 364         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 365         if (!val || strcmp(val->ident->name, "__val") != 0)
 366                 return NULL;
 367         return member_expression(expr, '.', val->ident);
 368 }
 369
 370 static void match__write_once_size(const char *fn, struct expression *call,
 371                                void *unused)
 372 {
 373         struct expression *dest, *data, *assign;
 374         struct range_list *rl;
 375
 376         dest = get_argument_from_call_expr(call->args, 0);
 377         if (dest->type != EXPR_PREOP || dest->op != '&')
 378                 return;
 379         dest = strip_expr(dest->unop);
 380
 381         data = get_argument_from_call_expr(call->args, 1);
 382         data = get_val_expr(data);
 383         if (!data)
 384                 return;
 385         get_absolute_rl(data, &rl);
 386         assign = assign_expression(dest, '=', data);
 387
 388         __in_fake_assign++;
 389         __split_expr(assign);
 390         __in_fake_assign--;
 391 }
 392
 393 static void match__read_once_size(const char *fn, struct expression *call,
 394                                void *unused)
 395 {
 396         struct expression *dest, *data, *assign;
 397         struct symbol *type, *val_sym;
 398
 399         /*
 400          * We want to change:
 401          *      __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
 402          * into a fake assignment:
 403          *      __u.val = x;
 404          *
 405          */
 406
 407         data = get_argument_from_call_expr(call->args, 0);
 408         if (data->type != EXPR_PREOP || data->op != '&')
 409                 return;
 410         data = strip_parens(data->unop);
 411
 412         dest = get_argument_from_call_expr(call->args, 1);
 413         if (dest->type != EXPR_DEREF || dest->op != '.')
 414                 return;
 415         if (!dest->member || strcmp(dest->member->name, "__c") != 0)
 416                 return;
 417         dest = dest->deref;
 418         type = get_type(dest);
 419         if (!type)
 420                 return;
 421         val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
 422         dest = member_expression(dest, '.', val_sym->ident);
 423
 424         assign = assign_expression(dest, '=', data);
 425         __in_fake_assign++;
 426         __split_expr(assign);
 427         __in_fake_assign--;
 428 }
 429
 430 static void match_closure_call(const char *name, struct expression *call,
 431                                void *unused)
 432 {
 433         struct expression *cl, *fn, *fake_call;
 434         struct expression_list *args = NULL;
 435
 436         cl = get_argument_from_call_expr(call->args, 0);
 437         fn = get_argument_from_call_expr(call->args, 1);
 438         if (!fn || !cl)
 439                 return;
 440
 441         add_ptr_list(&args, cl);
 442         fake_call = call_expression(fn, args);
 443         __split_expr(fake_call);
 444 }
 445
 446 static void match_kernel_param(struct symbol *sym)
 447 {
 448         struct expression *var;
 449         struct symbol *type;
 450
 451         /* This was designed to parse the module_param_named() macro */
 452
 453         if (!sym->ident ||
 454             !sym->initializer ||
 455             sym->initializer->type != EXPR_INITIALIZER)
 456                 return;
 457
 458         type = get_real_base_type(sym);
 459         if (!type || type->type != SYM_STRUCT || !type->ident)
 460                 return;
 461         if (strcmp(type->ident->name, "kernel_param") != 0)
 462                 return;
 463
 464         var = last_ptr_list((struct ptr_list *)sym->initializer->expr_list);
 465         if (!var || var->type != EXPR_INITIALIZER)
 466                 return;
 467         var = first_ptr_list((struct ptr_list *)var->expr_list);
 468         if (!var || var->type != EXPR_PREOP || var->op != '&')
 469                 return;
 470         var = strip_expr(var->unop);
 471
 472         type = get_type(var);
 473         update_mtag_data(var, alloc_estate_whole(type));
 474 }
 475
 476 bool is_ignored_kernel_data(const char *name)
 477 {
 478         if (option_project != PROJ_KERNEL)
 479                 return false;
 480
 481         /*
 482          * On the file I was looking at lockdep was 25% of the DB.
 483          */
 484         if (strstr(name, ".dep_map."))
 485                 return true;
 486         if (strstr(name, ".lockdep_map."))
 487                 return true;
 488         return false;
 489 }
 490
 491 void check_kernel(int id)
 492 {
 493         if (option_project != PROJ_KERNEL)
 494                 return;
 495
 496         err_ptr_min = sval_cast(&ptr_ctype, err_ptr_min);
 497         err_ptr_max = sval_cast(&ptr_ctype, err_ptr_max);
 498
 499         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 500         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 501         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 502         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 503         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 504         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 505         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 506         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 507         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 508
 509         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 510         add_hook(match_container_of, ASSIGNMENT_HOOK);
 511
 512         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 513         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 514         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 515         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 516
 517         add_implied_return_hook("fls", &match_fls, NULL);
 518         add_implied_return_hook("fls64", &match_fls, NULL);
 519
 520         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 521         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 522
 523         add_function_hook("__read_once_size", &match__read_once_size, NULL);
 524         add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
 525
 526         add_function_hook("closure_call", &match_closure_call, NULL);
 527
 528         add_hook(&match_kernel_param, BASE_HOOK);
 529
 530         if (option_info)
 531                 add_hook(match_end_file, END_FILE_HOOK);
 532 }