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