src/common/event-rule/kernel-kprobe.c

   1 /*
   2  * Copyright (C) 2019 Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #include <common/credentials.h>
   9 #include <common/error.h>
  10 #include <common/hashtable/hashtable.h>
  11 #include <common/hashtable/utils.h>
  12 #include <common/macros.h>
  13 #include <common/mi-lttng.h>
  14 #include <common/payload-view.h>
  15 #include <common/payload.h>
  16 #include <common/runas.h>
  17 #include <ctype.h>
  18 #include <lttng/constant.h>
  19 #include <lttng/event-rule/event-rule-internal.h>
  20 #include <lttng/event-rule/event-rule.h>
  21 #include <lttng/event-rule/kernel-kprobe-internal.h>
  22 #include <lttng/kernel-probe-internal.h>
  23 #include <lttng/kernel-probe.h>
  24 #include <stdio.h>
  25
  26 #define IS_KPROBE_EVENT_RULE(rule) \
  27         (lttng_event_rule_get_type(rule) == LTTNG_EVENT_RULE_TYPE_KERNEL_KPROBE)
  28
  29 #if (LTTNG_SYMBOL_NAME_LEN == 256)
  30 #define LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API "255"
  31 #endif
  32
  33 static void lttng_event_rule_kernel_kprobe_destroy(struct lttng_event_rule *rule)
  34 {
  35         struct lttng_event_rule_kernel_kprobe *kprobe;
  36
  37         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
  38
  39         lttng_kernel_probe_location_destroy(kprobe->location);
  40         free(kprobe->name);
  41         free(kprobe);
  42 }
  43
  44 static bool lttng_event_rule_kernel_kprobe_validate(
  45                 const struct lttng_event_rule *rule)
  46 {
  47         bool valid = false;
  48         struct lttng_event_rule_kernel_kprobe *kprobe;
  49
  50         if (!rule) {
  51                 goto end;
  52         }
  53
  54         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
  55
  56         /* Required field. */
  57         if (!kprobe->name) {
  58                 ERR("Invalid name event rule: a name must be set.");
  59                 goto end;
  60         }
  61
  62         /* Required field. */
  63         if(!kprobe->location) {
  64                 ERR("Invalid name event rule: a location must be set.");
  65                 goto end;
  66         }
  67
  68         valid = true;
  69 end:
  70         return valid;
  71 }
  72
  73 static int lttng_event_rule_kernel_kprobe_serialize(
  74                 const struct lttng_event_rule *rule,
  75                 struct lttng_payload *payload)
  76 {
  77         int ret;
  78         size_t name_len, header_offset, size_before_location;
  79         struct lttng_event_rule_kernel_kprobe *kprobe;
  80         struct lttng_event_rule_kernel_kprobe_comm kprobe_comm;
  81         struct lttng_event_rule_kernel_kprobe_comm *header;
  82
  83         if (!rule || !IS_KPROBE_EVENT_RULE(rule)) {
  84                 ret = -1;
  85                 goto end;
  86         }
  87
  88         header_offset = payload->buffer.size;
  89
  90         DBG("Serializing kprobe event rule.");
  91         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
  92
  93         name_len = strlen(kprobe->name) + 1;
  94         kprobe_comm.name_len = name_len;
  95
  96         ret = lttng_dynamic_buffer_append(
  97                         &payload->buffer, &kprobe_comm, sizeof(kprobe_comm));
  98         if (ret) {
  99                 goto end;
 100         }
 101
 102         ret = lttng_dynamic_buffer_append(&payload->buffer, kprobe->name, name_len);
 103         if (ret) {
 104                 goto end;
 105         }
 106
 107         size_before_location = payload->buffer.size;
 108
 109         ret = lttng_kernel_probe_location_serialize(kprobe->location, payload);
 110         if (ret < 0) {
 111                 goto end;
 112         }
 113
 114         /* Update the header regarding the probe size. */
 115         header = (struct lttng_event_rule_kernel_kprobe_comm*) (
 116                         (char *) payload->buffer.data + header_offset);
 117         header->location_len = payload->buffer.size - size_before_location;
 118
 119         ret = 0;
 120
 121 end:
 122         return ret;
 123 }
 124
 125 static bool lttng_event_rule_kernel_kprobe_is_equal(const struct lttng_event_rule *_a,
 126                 const struct lttng_event_rule *_b)
 127 {
 128         bool is_equal = false;
 129         struct lttng_event_rule_kernel_kprobe *a, *b;
 130
 131         a = container_of(_a, struct lttng_event_rule_kernel_kprobe, parent);
 132         b = container_of(_b, struct lttng_event_rule_kernel_kprobe, parent);
 133
 134         /* Quick checks */
 135         if (!!a->name != !!b->name) {
 136                 goto end;
 137         }
 138
 139         /* Long check */
 140         LTTNG_ASSERT(a->name);
 141         LTTNG_ASSERT(b->name);
 142         if (strcmp(a->name, b->name)) {
 143                 goto end;
 144         }
 145
 146         is_equal = lttng_kernel_probe_location_is_equal(
 147                         a->location, b->location);
 148 end:
 149         return is_equal;
 150 }
 151
 152 static enum lttng_error_code lttng_event_rule_kernel_kprobe_generate_filter_bytecode(
 153                 struct lttng_event_rule *rule,
 154                 const struct lttng_credentials *creds)
 155 {
 156         /* Nothing to do. */
 157         return LTTNG_OK;
 158 }
 159
 160 static const char *lttng_event_rule_kernel_kprobe_get_filter(
 161                 const struct lttng_event_rule *rule)
 162 {
 163         /* Not supported. */
 164         return NULL;
 165 }
 166
 167 static const struct lttng_bytecode *
 168 lttng_event_rule_kernel_kprobe_get_filter_bytecode(const struct lttng_event_rule *rule)
 169 {
 170         /* Not supported. */
 171         return NULL;
 172 }
 173
 174 static enum lttng_event_rule_generate_exclusions_status
 175 lttng_event_rule_kernel_kprobe_generate_exclusions(const struct lttng_event_rule *rule,
 176                 struct lttng_event_exclusion **exclusions)
 177 {
 178         /* Not supported. */
 179         *exclusions = NULL;
 180         return LTTNG_EVENT_RULE_GENERATE_EXCLUSIONS_STATUS_NONE;
 181 }
 182
 183 static unsigned long
 184 lttng_event_rule_kernel_kprobe_hash(
 185                 const struct lttng_event_rule *rule)
 186 {
 187         unsigned long hash;
 188         struct lttng_event_rule_kernel_kprobe *krule =
 189                         container_of(rule, typeof(*krule), parent);
 190
 191         hash = hash_key_ulong((void *) LTTNG_EVENT_RULE_TYPE_KERNEL_KPROBE,
 192                         lttng_ht_seed);
 193         hash ^= hash_key_str(krule->name, lttng_ht_seed);
 194         hash ^= lttng_kernel_probe_location_hash(krule->location);
 195
 196         return hash;
 197 }
 198
 199 static
 200 int kernel_probe_set_location(
 201                 struct lttng_event_rule_kernel_kprobe *kprobe,
 202                 const struct lttng_kernel_probe_location *location)
 203 {
 204         int ret;
 205         struct lttng_kernel_probe_location *location_copy = NULL;
 206
 207         if (!kprobe || !location || kprobe->location) {
 208                 ret = -1;
 209                 goto end;
 210         }
 211
 212         location_copy = lttng_kernel_probe_location_copy(location);
 213         if (!location_copy) {
 214                 ret = -1;
 215                 goto end;
 216         }
 217
 218         kprobe->location = location_copy;
 219         location_copy = NULL;
 220         ret = 0;
 221 end:
 222         lttng_kernel_probe_location_destroy(location_copy);
 223         return ret;
 224 }
 225
 226 static
 227 enum lttng_error_code lttng_event_rule_kernel_kprobe_mi_serialize(
 228                 const struct lttng_event_rule *rule, struct mi_writer *writer)
 229 {
 230         int ret;
 231         enum lttng_error_code ret_code;
 232         enum lttng_event_rule_status status;
 233         const char *event_name = NULL;
 234         const struct lttng_kernel_probe_location *location = NULL;
 235
 236         LTTNG_ASSERT(rule);
 237         LTTNG_ASSERT(writer);
 238         LTTNG_ASSERT(IS_KPROBE_EVENT_RULE(rule));
 239
 240         status = lttng_event_rule_kernel_kprobe_get_event_name(
 241                         rule, &event_name);
 242         LTTNG_ASSERT(status == LTTNG_EVENT_RULE_STATUS_OK);
 243         LTTNG_ASSERT(event_name);
 244
 245         status = lttng_event_rule_kernel_kprobe_get_location(rule, &location);
 246         LTTNG_ASSERT(status == LTTNG_EVENT_RULE_STATUS_OK);
 247         LTTNG_ASSERT(location);
 248
 249         /* Open event rule kernel kprobe element. */
 250         ret = mi_lttng_writer_open_element(
 251                         writer, mi_lttng_element_event_rule_kernel_kprobe);
 252         if (ret) {
 253                 goto mi_error;
 254         }
 255
 256         /* Name. */
 257         ret = mi_lttng_writer_write_element_string(writer,
 258                         mi_lttng_element_event_rule_event_name, event_name);
 259         if (ret) {
 260                 goto mi_error;
 261         }
 262
 263         /* Probe location. */
 264         ret_code = lttng_kernel_probe_location_mi_serialize(location, writer);
 265         if (ret_code != LTTNG_OK) {
 266                 goto end;
 267         }
 268
 269         /* Close event rule kernel kprobe element. */
 270         ret = mi_lttng_writer_close_element(writer);
 271         if (ret) {
 272                 goto mi_error;
 273         }
 274
 275         ret_code = LTTNG_OK;
 276         goto end;
 277
 278 mi_error:
 279         ret_code = LTTNG_ERR_MI_IO_FAIL;
 280 end:
 281         return ret_code;
 282 }
 283
 284 struct lttng_event_rule *lttng_event_rule_kernel_kprobe_create(
 285                 const struct lttng_kernel_probe_location *location)
 286 {
 287         struct lttng_event_rule *rule = NULL;
 288         struct lttng_event_rule_kernel_kprobe *krule;
 289
 290         krule = zmalloc(sizeof(struct lttng_event_rule_kernel_kprobe));
 291         if (!krule) {
 292                 goto end;
 293         }
 294
 295         rule = &krule->parent;
 296         lttng_event_rule_init(&krule->parent, LTTNG_EVENT_RULE_TYPE_KERNEL_KPROBE);
 297         krule->parent.validate = lttng_event_rule_kernel_kprobe_validate;
 298         krule->parent.serialize = lttng_event_rule_kernel_kprobe_serialize;
 299         krule->parent.equal = lttng_event_rule_kernel_kprobe_is_equal;
 300         krule->parent.destroy = lttng_event_rule_kernel_kprobe_destroy;
 301         krule->parent.generate_filter_bytecode =
 302                         lttng_event_rule_kernel_kprobe_generate_filter_bytecode;
 303         krule->parent.get_filter = lttng_event_rule_kernel_kprobe_get_filter;
 304         krule->parent.get_filter_bytecode =
 305                         lttng_event_rule_kernel_kprobe_get_filter_bytecode;
 306         krule->parent.generate_exclusions =
 307                         lttng_event_rule_kernel_kprobe_generate_exclusions;
 308         krule->parent.hash = lttng_event_rule_kernel_kprobe_hash;
 309         krule->parent.mi_serialize = lttng_event_rule_kernel_kprobe_mi_serialize;
 310
 311         if (kernel_probe_set_location(krule, location)) {
 312                 lttng_event_rule_destroy(rule);
 313                 rule = NULL;
 314         }
 315
 316 end:
 317         return rule;
 318 }
 319
 320 LTTNG_HIDDEN
 321 ssize_t lttng_event_rule_kernel_kprobe_create_from_payload(
 322                 struct lttng_payload_view *view,
 323                 struct lttng_event_rule **_event_rule)
 324 {
 325         ssize_t ret, offset = 0;
 326         enum lttng_event_rule_status status;
 327         const struct lttng_event_rule_kernel_kprobe_comm *kprobe_comm;
 328         const char *name;
 329         struct lttng_buffer_view current_buffer_view;
 330         struct lttng_event_rule *rule = NULL;
 331         struct lttng_kernel_probe_location *location = NULL;
 332
 333         if (!_event_rule) {
 334                 ret = -1;
 335                 goto end;
 336         }
 337
 338         current_buffer_view = lttng_buffer_view_from_view(
 339                         &view->buffer, offset, sizeof(*kprobe_comm));
 340         if (!lttng_buffer_view_is_valid(&current_buffer_view)) {
 341                 ERR("Failed to initialize from malformed event rule kprobe: buffer too short to contain header.");
 342                 ret = -1;
 343                 goto end;
 344         }
 345
 346         kprobe_comm = (typeof(kprobe_comm)) current_buffer_view.data;
 347
 348         /* Skip to payload */
 349         offset += current_buffer_view.size;
 350
 351         {
 352                 /* Map the name. */
 353                 struct lttng_payload_view current_payload_view =
 354                                 lttng_payload_view_from_view(view, offset,
 355                                                 kprobe_comm->name_len);
 356
 357                 if (!lttng_payload_view_is_valid(&current_payload_view)) {
 358                         ret = -1;
 359                         goto end;
 360                 }
 361
 362                 name = current_payload_view.buffer.data;
 363                 if (!lttng_buffer_view_contains_string(
 364                                 &current_payload_view.buffer, name,
 365                                 kprobe_comm->name_len)) {
 366                         ret = -1;
 367                         goto end;
 368                 }
 369         }
 370
 371         /* Skip after the name. */
 372         offset += kprobe_comm->name_len;
 373
 374         /* Map the kernel probe location. */
 375         {
 376                 struct lttng_payload_view current_payload_view =
 377                                 lttng_payload_view_from_view(view, offset,
 378                                                 kprobe_comm->location_len);
 379
 380                 if (!lttng_payload_view_is_valid(&current_payload_view)) {
 381                         ret = -1;
 382                         goto end;
 383                 }
 384
 385                 ret = lttng_kernel_probe_location_create_from_payload(
 386                                 &current_payload_view, &location);
 387                 if (ret < 0) {
 388                         ret = -1;
 389                         goto end;
 390                 }
 391         }
 392
 393         if (ret != kprobe_comm->location_len) {
 394                 ret = -1;
 395                 goto end;
 396         }
 397
 398         /* Skip after the location */
 399         offset += kprobe_comm->location_len;
 400
 401         rule = lttng_event_rule_kernel_kprobe_create(location);
 402         if (!rule) {
 403                 ERR("Failed to create event rule kprobe.");
 404                 ret = -1;
 405                 goto end;
 406         }
 407
 408         status = lttng_event_rule_kernel_kprobe_set_event_name(rule, name);
 409         if (status != LTTNG_EVENT_RULE_STATUS_OK) {
 410                 ERR("Failed to set event rule kprobe name.");
 411                 ret = -1;
 412                 goto end;
 413         }
 414
 415         *_event_rule = rule;
 416         rule = NULL;
 417         ret = offset;
 418 end:
 419         lttng_kernel_probe_location_destroy(location);
 420         lttng_event_rule_destroy(rule);
 421         return ret;
 422 }
 423
 424 enum lttng_event_rule_status lttng_event_rule_kernel_kprobe_get_location(
 425                 const struct lttng_event_rule *rule,
 426                 const struct lttng_kernel_probe_location **location)
 427 {
 428         enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
 429         struct lttng_event_rule_kernel_kprobe *kprobe;
 430
 431         if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !location) {
 432                 status = LTTNG_EVENT_RULE_STATUS_INVALID;
 433                 goto end;
 434         }
 435
 436         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
 437         *location = kprobe->location;
 438
 439         if (!*location) {
 440                 status = LTTNG_EVENT_RULE_STATUS_UNSET;
 441                 goto end;
 442         }
 443
 444 end:
 445         return status;
 446 }
 447
 448 enum lttng_event_rule_status lttng_event_rule_kernel_kprobe_set_event_name(
 449                 struct lttng_event_rule *rule, const char *name)
 450 {
 451         char *name_copy = NULL;
 452         struct lttng_event_rule_kernel_kprobe *kprobe;
 453         enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
 454
 455         if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !name ||
 456                         strlen(name) == 0) {
 457                 status = LTTNG_EVENT_RULE_STATUS_INVALID;
 458                 goto end;
 459         }
 460
 461         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
 462         name_copy = strdup(name);
 463         if (!name_copy) {
 464                 status = LTTNG_EVENT_RULE_STATUS_ERROR;
 465                 goto end;
 466         }
 467
 468         free(kprobe->name);
 469
 470         kprobe->name = name_copy;
 471         name_copy = NULL;
 472 end:
 473         return status;
 474 }
 475
 476 enum lttng_event_rule_status lttng_event_rule_kernel_kprobe_get_event_name(
 477                 const struct lttng_event_rule *rule, const char **name)
 478 {
 479         struct lttng_event_rule_kernel_kprobe *kprobe;
 480         enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
 481
 482         if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !name) {
 483                 status = LTTNG_EVENT_RULE_STATUS_INVALID;
 484                 goto end;
 485         }
 486
 487         kprobe = container_of(rule, struct lttng_event_rule_kernel_kprobe, parent);
 488         if (!kprobe->name) {
 489                 status = LTTNG_EVENT_RULE_STATUS_UNSET;
 490                 goto end;
 491         }
 492
 493         *name = kprobe->name;
 494 end:
 495         return status;
 496 }