smatch_container_of.c

   1 /*
   2  * Copyright (C) 2017 Oracle.
   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 #include "smatch.h"
  19 #include "smatch_slist.h"
  20 #include "smatch_extra.h"
  21
  22 static int my_id;
  23 static int param_id;
  24
  25 static struct stree *used_stree;
  26 static struct stree_stack *saved_stack;
  27
  28 STATE(used);
  29
  30 int get_param_from_container_of(struct expression *expr)
  31 {
  32         struct expression *param_expr;
  33         struct symbol *type;
  34         sval_t sval;
  35         int param;
  36
  37
  38         type = get_type(expr);
  39         if (!type || type->type != SYM_PTR)
  40                 return -1;
  41
  42         expr = strip_expr(expr);
  43         if (expr->type != EXPR_BINOP || expr->op != '-')
  44                 return -1;
  45
  46         if (!get_value(expr->right, &sval))
  47                 return -1;
  48         if (sval.value < 0 || sval.value > 4096)
  49                 return -1;
  50
  51         param_expr = get_assigned_expr(expr->left);
  52         if (!param_expr)
  53                 return -1;
  54         param = get_param_num(param_expr);
  55         if (param < 0)
  56                 return -1;
  57
  58         return param;
  59 }
  60
  61 int get_offset_from_container_of(struct expression *expr)
  62 {
  63         struct expression *param_expr;
  64         struct symbol *type;
  65         sval_t sval;
  66
  67         type = get_type(expr);
  68         if (!type || type->type != SYM_PTR)
  69                 return -1;
  70
  71         expr = strip_expr(expr);
  72         if (expr->type != EXPR_BINOP || expr->op != '-')
  73                 return -1;
  74
  75         if (!get_value(expr->right, &sval))
  76                 return -1;
  77         if (sval.value < 0 || sval.value > 4096)
  78                 return -1;
  79
  80         param_expr = get_assigned_expr(expr->left);
  81         if (!param_expr)
  82                 return -1;
  83
  84         return sval.value;
  85 }
  86
  87 static int get_container_arg(struct symbol *sym)
  88 {
  89         struct expression *__mptr;
  90         int param;
  91
  92         if (!sym || !sym->ident)
  93                 return -1;
  94
  95         __mptr = get_assigned_expr_name_sym(sym->ident->name, sym);
  96         param = get_param_from_container_of(__mptr);
  97
  98         return param;
  99 }
 100
 101 static int get_container_offset(struct symbol *sym)
 102 {
 103         struct expression *__mptr;
 104         int offset;
 105
 106         if (!sym || !sym->ident)
 107                 return -1;
 108
 109         __mptr = get_assigned_expr_name_sym(sym->ident->name, sym);
 110         offset = get_offset_from_container_of(__mptr);
 111
 112         return offset;
 113 }
 114
 115 static char *get_container_name(struct sm_state *sm, int offset)
 116 {
 117         static char buf[256];
 118         const char *name;
 119
 120         name = get_param_name(sm);
 121         if (!name)
 122                 return NULL;
 123
 124         if (name[0] == '$')
 125                 snprintf(buf, sizeof(buf), "$(-%d)%s", offset, name + 1);
 126         else if (name[0] == '*' || name[1] == '$')
 127                 snprintf(buf, sizeof(buf), "*$(-%d)%s", offset, name + 2);
 128         else
 129                 return NULL;
 130
 131         return buf;
 132 }
 133
 134 static void get_state_hook(int owner, const char *name, struct symbol *sym)
 135 {
 136         int arg;
 137
 138         if (!option_info)
 139                 return;
 140         if (__in_fake_assign)
 141                 return;
 142
 143         arg = get_container_arg(sym);
 144         if (arg >= 0)
 145                 set_state_stree(&used_stree, my_id, name, sym, &used);
 146 }
 147
 148 static void set_param_used(struct expression *call, struct expression *arg, char *key, char *unused)
 149 {
 150         struct symbol *sym;
 151         char *name;
 152         int arg_nr;
 153
 154         name = get_variable_from_key(arg, key, &sym);
 155         if (!name || !sym)
 156                 goto free;
 157
 158         arg_nr = get_container_arg(sym);
 159         if (arg_nr >= 0)
 160                 set_state(my_id, name, sym, &used);
 161 free:
 162         free_string(name);
 163 }
 164
 165 static void process_states(void)
 166 {
 167         struct sm_state *tmp;
 168         int arg, offset;
 169         const char *name;
 170
 171         FOR_EACH_SM(used_stree, tmp) {
 172                 arg = get_container_arg(tmp->sym);
 173                 offset = get_container_offset(tmp->sym);
 174                 if (arg < 0 || offset < 0)
 175                         continue;
 176                 name = get_container_name(tmp, offset);
 177                 if (!name)
 178                         continue;
 179                 sql_insert_call_implies(CONTAINER, arg, name, "");
 180         } END_FOR_EACH_SM(tmp);
 181
 182         free_stree(&used_stree);
 183 }
 184
 185 static void match_function_def(struct symbol *sym)
 186 {
 187         free_stree(&used_stree);
 188 }
 189
 190 static void match_save_states(struct expression *expr)
 191 {
 192         push_stree(&saved_stack, used_stree);
 193         used_stree = NULL;
 194 }
 195
 196 static void match_restore_states(struct expression *expr)
 197 {
 198         free_stree(&used_stree);
 199         used_stree = pop_stree(&saved_stack);
 200 }
 201
 202 static void print_returns_container_of(int return_id, char *return_ranges, struct expression *expr)
 203 {
 204         int offset;
 205         int param;
 206         char key[64];
 207         char value[64];
 208
 209         param = get_param_from_container_of(expr);
 210         if (param < 0)
 211                 return;
 212         offset = get_offset_from_container_of(expr);
 213         if (offset < 0)
 214                 return;
 215
 216         snprintf(key, sizeof(key), "%d", param);
 217         snprintf(value, sizeof(value), "-%d", offset);
 218
 219         /* no need to add it to call_implies because it's not really param_used */
 220         sql_insert_return_states(return_id, return_ranges, CONTAINER, -1,
 221                         key, value);
 222 }
 223
 224 static void returns_container_of(struct expression *expr, int param, char *key, char *value)
 225 {
 226         struct expression *call, *arg;
 227         int offset;
 228         char buf[64];
 229
 230         if (expr->type != EXPR_ASSIGNMENT || expr->op != '=')
 231                 return;
 232         call = strip_expr(expr->right);
 233         if (call->type != EXPR_CALL)
 234                 return;
 235         if (param != -1)
 236                 return;
 237         param = atoi(key);
 238         offset = atoi(value);
 239
 240         arg = get_argument_from_call_expr(call->args, param);
 241         if (!arg)
 242                 return;
 243         if (arg->type != EXPR_SYMBOL)
 244                 return;
 245         param = get_param_num(arg);
 246         if (param < 0)
 247                 return;
 248         snprintf(buf, sizeof(buf), "$(%d)", offset);
 249         sql_insert_call_implies(CONTAINER, param, buf, "");
 250 }
 251
 252 static struct expression *get_outer_struct(struct expression *expr)
 253 {
 254         struct expression *unop;
 255
 256         expr = strip_expr(expr);
 257         if (expr->type != EXPR_DEREF)
 258                 return NULL;
 259         unop = strip_expr(expr->deref);
 260         if (unop->type == EXPR_SYMBOL)
 261                 return unop;
 262         if (unop->type != EXPR_PREOP || unop->op != '*')
 263                 return NULL;
 264         return strip_expr(unop->unop);
 265 }
 266
 267 static void match_call(struct expression *call)
 268 {
 269         struct expression *ptr, *unop, *arg, *arg_unop;
 270         struct symbol *type;
 271         int i, offset;
 272         int arg_offset = 0;
 273         char offset_str[12];
 274         char param_str[12];
 275         bool star = 0;
 276
 277         ptr = strip_expr(call->fn);
 278         unop = get_outer_struct(ptr);
 279         if (!unop)
 280                 return;
 281
 282         i = -1;
 283         FOR_EACH_PTR(call->args, arg) {
 284                 i++;
 285                 if (expr_equiv(arg, unop))
 286                         goto found;
 287         } END_FOR_EACH_PTR(arg);
 288
 289         i = -1;
 290         FOR_EACH_PTR(call->args, arg) {
 291                 i++;
 292                 arg_unop = get_outer_struct(arg);
 293                 if (!arg_unop)
 294                         continue;
 295                 if (!expr_equiv(arg_unop, unop))
 296                         continue;
 297                 arg_offset = get_member_offset_from_deref(arg);
 298                 if (arg_offset < 0)
 299                         continue;
 300                 if (!is_pointer(arg))
 301                         star = 1;
 302                 goto found;
 303         } END_FOR_EACH_PTR(arg);
 304
 305         return;
 306
 307 found:
 308         type = get_type(unop);
 309         if (type && type->type == SYM_PTR)
 310                 type = get_real_base_type(type);
 311         offset = get_member_offset(type, ptr->member->name);
 312         if (offset < 0)
 313                 return;
 314
 315         if (star)
 316                 snprintf(offset_str, sizeof(offset_str), "*(-%d+%d)", offset, arg_offset);
 317         else
 318                 snprintf(offset_str, sizeof(offset_str), "-%d+%d", offset, arg_offset);
 319         snprintf(param_str, sizeof(param_str), "$%d", i);
 320         sql_insert_caller_info(call, CONTAINER, -1, offset_str, param_str);
 321 }
 322
 323 static void db_func_def(const char *name, struct symbol *sym, char *key, char *value)
 324 {
 325         sval_t offset = {
 326                 .type = &int_ctype,
 327         };
 328         const char *arg_offset;
 329         struct symbol *arg;
 330         int star = 0;
 331         int param;
 332         int val;
 333         int i;
 334
 335         if (name || sym)
 336                 return;
 337         if (key[0] == '*') {
 338                 star = 1;
 339                 key += 2;
 340         }
 341
 342         val = atoi(key);
 343         if (val < -4095 || val >= 0)
 344                 return;
 345         offset.value = -val;
 346         arg_offset = strchr(key, '+');
 347         if (!arg_offset)
 348                 return;
 349         val = atoi(arg_offset + 1);
 350         if (val > 4095 || val < 0)
 351                 return;
 352         offset.value |= val << 16;
 353         if (star)
 354                 offset.value |= 1ULL << 31;
 355
 356         if (value[0] != '$')
 357                 return;
 358
 359         param = atoi(value + 1);
 360
 361         i = -1;
 362         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 363                 i++;
 364                 if (param == i)
 365                         set_state(param_id, arg->ident->name, arg, alloc_estate_sval(offset));
 366         } END_FOR_EACH_PTR(arg);
 367 }
 368
 369 struct db_info {
 370         struct symbol *param_sym;
 371         const char *prev_key;
 372         struct range_list *rl;
 373 };
 374
 375 static void set_param_value(const char *key, struct symbol *sym, struct range_list *rl)
 376 {
 377         const char *name;
 378         char fullname[256];
 379
 380         if (!sym || !sym->ident)
 381                 return;
 382
 383         name = sym->ident->name;
 384         if (strcmp(key, "*$") == 0)
 385                 snprintf(fullname, sizeof(fullname), "*%s", name);
 386         else if (key[0] == '$')
 387                 snprintf(fullname, 256, "%s%s", name, key + 1);
 388         else
 389                 return;
 390
 391         set_state(SMATCH_EXTRA, fullname, sym, alloc_estate_rl(rl));
 392 }
 393
 394 static int save_vals(void *_db_info, int argc, char **argv, char **azColName)
 395 {
 396         struct db_info *db_info = _db_info;
 397         struct symbol *type;
 398         struct range_list *rl;
 399         const char *key;
 400         const char *value;
 401
 402         if (argc == 2) {
 403                 key = argv[0];
 404                 value = argv[1];
 405         } else {
 406                 key = "$";
 407                 value = argv[0];
 408         }
 409
 410         if (db_info->prev_key &&
 411             strcmp(db_info->prev_key, key) != 0) {
 412                 set_param_value(db_info->prev_key, db_info->param_sym, db_info->rl);
 413                 db_info->rl = NULL;
 414         }
 415
 416         db_info->prev_key = alloc_sname(key);
 417
 418         type = get_member_type_from_key(symbol_expression(db_info->param_sym), key);
 419         str_to_rl(type, (char *)value, &rl);
 420         if (db_info->rl)
 421                 db_info->rl = rl_union(db_info->rl, rl);
 422         else
 423                 db_info->rl = rl;
 424
 425         return 0;
 426 }
 427
 428 static void load_tag_info_sym(mtag_t tag, struct symbol *sym, int arg_offset, int star)
 429 {
 430         struct db_info db_info = {
 431                 .param_sym = sym,
 432         };
 433
 434         if (!tag)
 435                 return;
 436
 437         if (star) {
 438                 run_sql(save_vals, &db_info,
 439                         "select value from mtag_data where tag = %lld and offset = %d and type = %d;",
 440                         tag, arg_offset, DATA_VALUE);
 441         } else {
 442                 run_sql(save_vals, &db_info,
 443                         "select data, value from mtag_data where tag = %lld and type = %d;",
 444                         tag, DATA_VALUE);
 445         }
 446
 447         if (db_info.prev_key)
 448                 set_param_value(db_info.prev_key, db_info.param_sym, db_info.rl);
 449 }
 450
 451 static void handle_passed_container(struct symbol *sym)
 452 {
 453         struct symbol *arg;
 454         struct smatch_state *state;
 455         mtag_t fn_tag, container_tag, arg_tag;
 456         sval_t offset;
 457         int container_offset, arg_offset;
 458         int star;
 459
 460         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 461                 state = get_state(param_id, arg->ident->name, arg);
 462                 if (state)
 463                         goto found;
 464         } END_FOR_EACH_PTR(arg);
 465
 466         return;
 467 found:
 468         if (!estate_get_single_value(state, &offset))
 469                 return;
 470         container_offset = -(offset.value & 0xffff);
 471         arg_offset = -((offset.value & 0xfff0000) >> 16);
 472         star = !!(offset.value & (1ULL << 31));
 473
 474         if (!get_toplevel_mtag(cur_func_sym, &fn_tag))
 475                 return;
 476         if (!mtag_map_select_container(fn_tag, container_offset, &container_tag))
 477                 return;
 478         if (!arg_offset || star) {
 479                 arg_tag = container_tag;
 480         } else {
 481                 if (!mtag_map_select_tag(container_tag, arg_offset, &arg_tag))
 482                         return;
 483
 484         }
 485         load_tag_info_sym(arg_tag, arg, -arg_offset, star);
 486 }
 487
 488 void register_container_of(int id)
 489 {
 490         my_id = id;
 491
 492         add_hook(&match_function_def, FUNC_DEF_HOOK);
 493
 494         add_get_state_hook(&get_state_hook);
 495
 496         add_hook(&match_save_states, INLINE_FN_START);
 497         add_hook(&match_restore_states, INLINE_FN_END);
 498
 499         select_call_implies_hook(CONTAINER, &set_param_used);
 500         all_return_states_hook(&process_states);
 501
 502         add_split_return_callback(&print_returns_container_of);
 503         select_return_states_hook(CONTAINER, &returns_container_of);
 504
 505         add_hook(&match_call, FUNCTION_CALL_HOOK);
 506 }
 507
 508 static struct smatch_state *unmatched_state(struct sm_state *sm)
 509 {
 510         return alloc_estate_whole(estate_type(sm->state));
 511 }
 512
 513 void register_container_of2(int id)
 514 {
 515         param_id = id;
 516
 517         select_caller_info_hook(db_func_def, CONTAINER);
 518         add_hook(&handle_passed_container, AFTER_DEF_HOOK);
 519         add_unmatched_state_hook(param_id, &unmatched_state);
 520         add_merge_hook(param_id, &merge_estates);
 521 }
 522