src/common/event-rule/kernel-probe.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.h>
  20 #include <lttng/event-rule/event-rule-internal.h>
  21 #include <lttng/event-rule/kernel-probe-internal.h>
  22 #include <lttng/kernel-probe.h>
  23 #include <lttng/kernel-probe-internal.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_PROBE)
  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_probe_destroy(struct lttng_event_rule *rule)
  34 {
  35         struct lttng_event_rule_kernel_probe *kprobe;
  36
  37         kprobe = container_of(rule, struct lttng_event_rule_kernel_probe, 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_probe_validate(
  45                 const struct lttng_event_rule *rule)
  46 {
  47         bool valid = false;
  48         struct lttng_event_rule_kernel_probe *kprobe;
  49
  50         if (!rule) {
  51                 goto end;
  52         }
  53
  54         kprobe = container_of(rule, struct lttng_event_rule_kernel_probe, 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_probe_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_probe *kprobe;
  80         struct lttng_event_rule_kernel_probe_comm kprobe_comm;
  81         struct lttng_event_rule_kernel_probe_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_probe, 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_probe_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_probe_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_probe *a, *b;
 130
 131         a = container_of(_a, struct lttng_event_rule_kernel_probe, parent);
 132         b = container_of(_b, struct lttng_event_rule_kernel_probe, parent);
 133
 134         /* Quick checks */
 135         if (!!a->name != !!b->name) {
 136                 goto end;
 137         }
 138
 139         /* Long check */
 140         assert(a->name);
 141         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_probe_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_probe_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_probe_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_probe_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_probe_hash(
 185                 const struct lttng_event_rule *rule)
 186 {
 187         unsigned long hash;
 188         struct lttng_event_rule_kernel_probe *krule =
 189                         container_of(rule, typeof(*krule), parent);
 190
 191         hash = hash_key_ulong((void *) LTTNG_EVENT_RULE_TYPE_KERNEL_PROBE,
 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_probe *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 struct lttng_event_rule *lttng_event_rule_kernel_probe_create(
 227                 const struct lttng_kernel_probe_location *location)
 228 {
 229         struct lttng_event_rule *rule = NULL;
 230         struct lttng_event_rule_kernel_probe *krule;
 231
 232         krule = zmalloc(sizeof(struct lttng_event_rule_kernel_probe));
 233         if (!krule) {
 234                 goto end;
 235         }
 236
 237         rule = &krule->parent;
 238         lttng_event_rule_init(&krule->parent, LTTNG_EVENT_RULE_TYPE_KERNEL_PROBE);
 239         krule->parent.validate = lttng_event_rule_kernel_probe_validate;
 240         krule->parent.serialize = lttng_event_rule_kernel_probe_serialize;
 241         krule->parent.equal = lttng_event_rule_kernel_probe_is_equal;
 242         krule->parent.destroy = lttng_event_rule_kernel_probe_destroy;
 243         krule->parent.generate_filter_bytecode =
 244                         lttng_event_rule_kernel_probe_generate_filter_bytecode;
 245         krule->parent.get_filter = lttng_event_rule_kernel_probe_get_filter;
 246         krule->parent.get_filter_bytecode =
 247                         lttng_event_rule_kernel_probe_get_filter_bytecode;
 248         krule->parent.generate_exclusions =
 249                         lttng_event_rule_kernel_probe_generate_exclusions;
 250         krule->parent.hash = lttng_event_rule_kernel_probe_hash;
 251
 252         if (kernel_probe_set_location(krule, location)) {
 253                 lttng_event_rule_destroy(rule);
 254                 rule = NULL;
 255         }
 256
 257 end:
 258         return rule;
 259 }
 260
 261 LTTNG_HIDDEN
 262 ssize_t lttng_event_rule_kernel_probe_create_from_payload(
 263                 struct lttng_payload_view *view,
 264                 struct lttng_event_rule **_event_rule)
 265 {
 266         ssize_t ret, offset = 0;
 267         enum lttng_event_rule_status status;
 268         const struct lttng_event_rule_kernel_probe_comm *kprobe_comm;
 269         const char *name;
 270         struct lttng_buffer_view current_buffer_view;
 271         struct lttng_event_rule *rule = NULL;
 272         struct lttng_kernel_probe_location *location = NULL;
 273
 274         if (!_event_rule) {
 275                 ret = -1;
 276                 goto end;
 277         }
 278
 279         current_buffer_view = lttng_buffer_view_from_view(
 280                         &view->buffer, offset, sizeof(*kprobe_comm));
 281         if (!lttng_buffer_view_is_valid(&current_buffer_view)) {
 282                 ERR("Failed to initialize from malformed event rule kprobe: buffer too short to contain header.");
 283                 ret = -1;
 284                 goto end;
 285         }
 286
 287         kprobe_comm = (typeof(kprobe_comm)) current_buffer_view.data;
 288
 289         /* Skip to payload */
 290         offset += current_buffer_view.size;
 291
 292         {
 293                 /* Map the name. */
 294                 struct lttng_payload_view current_payload_view =
 295                                 lttng_payload_view_from_view(view, offset,
 296                                                 kprobe_comm->name_len);
 297
 298                 if (!lttng_payload_view_is_valid(&current_payload_view)) {
 299                         ret = -1;
 300                         goto end;
 301                 }
 302
 303                 name = current_payload_view.buffer.data;
 304                 if (!lttng_buffer_view_contains_string(
 305                                 &current_payload_view.buffer, name,
 306                                 kprobe_comm->name_len)) {
 307                         ret = -1;
 308                         goto end;
 309                 }
 310         }
 311
 312         /* Skip after the name. */
 313         offset += kprobe_comm->name_len;
 314
 315         /* Map the kernel probe location. */
 316         {
 317                 struct lttng_payload_view current_payload_view =
 318                                 lttng_payload_view_from_view(view, offset,
 319                                                 kprobe_comm->location_len);
 320
 321                 if (!lttng_payload_view_is_valid(&current_payload_view)) {
 322                         ret = -1;
 323                         goto end;
 324                 }
 325
 326                 ret = lttng_kernel_probe_location_create_from_payload(
 327                                 &current_payload_view, &location);
 328                 if (ret < 0) {
 329                         ret = -1;
 330                         goto end;
 331                 }
 332         }
 333
 334         if (ret != kprobe_comm->location_len) {
 335                 ret = -1;
 336                 goto end;
 337         }
 338
 339         /* Skip after the location */
 340         offset += kprobe_comm->location_len;
 341
 342         rule = lttng_event_rule_kernel_probe_create(location);
 343         if (!rule) {
 344                 ERR("Failed to create event rule kprobe.");
 345                 ret = -1;
 346                 goto end;
 347         }
 348
 349         status = lttng_event_rule_kernel_probe_set_event_name(rule, name);
 350         if (status != LTTNG_EVENT_RULE_STATUS_OK) {
 351                 ERR("Failed to set event rule kprobe name.");
 352                 ret = -1;
 353                 goto end;
 354         }
 355
 356         *_event_rule = rule;
 357         rule = NULL;
 358         ret = offset;
 359 end:
 360         lttng_kernel_probe_location_destroy(location);
 361         lttng_event_rule_destroy(rule);
 362         return ret;
 363 }
 364
 365 enum lttng_event_rule_status lttng_event_rule_kernel_probe_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_kernel_probe *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_kernel_probe, 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_kernel_probe_set_event_name(
 390                 struct lttng_event_rule *rule, const char *name)
 391 {
 392         char *name_copy = NULL;
 393         struct lttng_event_rule_kernel_probe *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_kernel_probe, 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_kernel_probe_get_event_name(
 418                 const struct lttng_event_rule *rule, const char **name)
 419 {
 420         struct lttng_event_rule_kernel_probe *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_kernel_probe, 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 }