event-rule: introduce event-rule kprobe
[lttng-tools.git] / src / common / event-rule / kprobe.c
diff --git a/src/common/event-rule/kprobe.c b/src/common/event-rule/kprobe.c
new file mode 100644 (file)
index 0000000..a5c93e6
--- /dev/null
@@ -0,0 +1,413 @@
+/*
+ * Copyright (C) 2019 Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#include <assert.h>
+#include <common/error.h>
+#include <common/macros.h>
+#include <common/payload.h>
+#include <common/payload-view.h>
+#include <common/runas.h>
+#include <ctype.h>
+#include <lttng/constant.h>
+#include <lttng/event-rule/event-rule-internal.h>
+#include <lttng/event-rule/kprobe-internal.h>
+#include <lttng/kernel-probe.h>
+#include <lttng/kernel-probe-internal.h>
+#include <stdio.h>
+
+#define IS_KPROBE_EVENT_RULE(rule) \
+       (lttng_event_rule_get_type(rule) == LTTNG_EVENT_RULE_TYPE_KPROBE)
+
+#if (LTTNG_SYMBOL_NAME_LEN == 256)
+#define LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API "255"
+#endif
+
+static void lttng_event_rule_kprobe_destroy(struct lttng_event_rule *rule)
+{
+       struct lttng_event_rule_kprobe *kprobe;
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+
+       lttng_kernel_probe_location_destroy(kprobe->location);
+       free(kprobe->name);
+       free(kprobe);
+}
+
+static bool lttng_event_rule_kprobe_validate(
+               const struct lttng_event_rule *rule)
+{
+       bool valid = false;
+       struct lttng_event_rule_kprobe *kprobe;
+
+       if (!rule) {
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+
+       /* Required field. */
+       if (!kprobe->name) {
+               ERR("Invalid name event rule: a name must be set.");
+               goto end;
+       }
+
+       /* Required field. */
+       if(!kprobe->location) {
+               ERR("Invalid name event rule: a location must be set.");
+               goto end;
+       }
+
+       valid = true;
+end:
+       return valid;
+}
+
+static int lttng_event_rule_kprobe_serialize(
+               const struct lttng_event_rule *rule,
+               struct lttng_payload *payload)
+{
+       int ret;
+       size_t name_len, header_offset, size_before_location;
+       struct lttng_event_rule_kprobe *kprobe;
+       struct lttng_event_rule_kprobe_comm kprobe_comm;
+       struct lttng_event_rule_kprobe_comm *header;
+
+       if (!rule || !IS_KPROBE_EVENT_RULE(rule)) {
+               ret = -1;
+               goto end;
+       }
+
+       header_offset = payload->buffer.size;
+
+       DBG("Serializing kprobe event rule.");
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+
+       name_len = strlen(kprobe->name) + 1;
+       kprobe_comm.name_len = name_len;
+
+       ret = lttng_dynamic_buffer_append(
+                       &payload->buffer, &kprobe_comm, sizeof(kprobe_comm));
+       if (ret) {
+               goto end;
+       }
+
+       ret = lttng_dynamic_buffer_append(&payload->buffer, kprobe->name, name_len);
+       if (ret) {
+               goto end;
+       }
+
+       size_before_location = payload->buffer.size;
+
+       ret = lttng_kernel_probe_location_serialize(kprobe->location, payload);
+       if (ret < 0) {
+               goto end;
+       }
+
+       /* Update the header regarding the probe size. */
+       header = (struct lttng_event_rule_kprobe_comm*) (
+                       (char *) payload->buffer.data + header_offset);
+       header->location_len = payload->buffer.size - size_before_location;
+
+       ret = 0;
+
+end:
+       return ret;
+}
+
+static bool lttng_event_rule_kprobe_is_equal(const struct lttng_event_rule *_a,
+               const struct lttng_event_rule *_b)
+{
+       bool is_equal = false;
+       struct lttng_event_rule_kprobe *a, *b;
+
+       a = container_of(_a, struct lttng_event_rule_kprobe, parent);
+       b = container_of(_b, struct lttng_event_rule_kprobe, parent);
+
+       /* Quick checks */
+       if (!!a->name != !!b->name) {
+               goto end;
+       }
+
+       /* Long check */
+       assert(a->name);
+       assert(b->name);
+       if (strcmp(a->name, b->name)) {
+               goto end;
+       }
+
+       is_equal = lttng_kernel_probe_location_is_equal(
+                       a->location, b->location);
+end:
+       return is_equal;
+}
+
+static enum lttng_error_code lttng_event_rule_kprobe_generate_filter_bytecode(
+               struct lttng_event_rule *rule, uid_t uid, gid_t gid)
+{
+       /* Nothing to do. */
+       return LTTNG_OK;
+}
+
+static const char *lttng_event_rule_kprobe_get_filter(
+               const struct lttng_event_rule *rule)
+{
+       /* Not supported. */
+       return NULL;
+}
+
+static const struct lttng_filter_bytecode *
+lttng_event_rule_kprobe_get_filter_bytecode(const struct lttng_event_rule *rule)
+{
+       /* Not supported. */
+       return NULL;
+}
+
+static struct lttng_event_exclusion *
+lttng_event_rule_kprobe_generate_exclusions(const struct lttng_event_rule *rule)
+{
+       /* Not supported. */
+       return NULL;
+}
+
+struct lttng_event_rule *lttng_event_rule_kprobe_create()
+{
+       struct lttng_event_rule *rule = NULL;
+       struct lttng_event_rule_kprobe *krule;
+
+       krule = zmalloc(sizeof(struct lttng_event_rule_kprobe));
+       if (!krule) {
+               goto end;
+       }
+
+       rule = &krule->parent;
+       lttng_event_rule_init(&krule->parent, LTTNG_EVENT_RULE_TYPE_KPROBE);
+       krule->parent.validate = lttng_event_rule_kprobe_validate;
+       krule->parent.serialize = lttng_event_rule_kprobe_serialize;
+       krule->parent.equal = lttng_event_rule_kprobe_is_equal;
+       krule->parent.destroy = lttng_event_rule_kprobe_destroy;
+       krule->parent.generate_filter_bytecode =
+                       lttng_event_rule_kprobe_generate_filter_bytecode;
+       krule->parent.get_filter = lttng_event_rule_kprobe_get_filter;
+       krule->parent.get_filter_bytecode =
+                       lttng_event_rule_kprobe_get_filter_bytecode;
+       krule->parent.generate_exclusions =
+                       lttng_event_rule_kprobe_generate_exclusions;
+end:
+       return rule;
+}
+
+LTTNG_HIDDEN
+ssize_t lttng_event_rule_kprobe_create_from_payload(
+               struct lttng_payload_view *view,
+               struct lttng_event_rule **_event_rule)
+{
+       ssize_t ret, offset = 0;
+       enum lttng_event_rule_status status;
+       const struct lttng_event_rule_kprobe_comm *kprobe_comm;
+       const char *name;
+       struct lttng_buffer_view current_buffer_view;
+       struct lttng_event_rule *rule = NULL;
+       struct lttng_event_rule_kprobe *kprobe = NULL;
+       struct lttng_kernel_probe_location *location;
+
+       if (!_event_rule) {
+               ret = -1;
+               goto end;
+       }
+
+       if (view->buffer.size < sizeof(*kprobe_comm)) {
+               ERR("Failed to initialize from malformed event rule kprobe: buffer too short to contain header.");
+               ret = -1;
+               goto end;
+       }
+
+       current_buffer_view = lttng_buffer_view_from_view(
+                       &view->buffer, offset, sizeof(*kprobe_comm));
+       kprobe_comm = (typeof(kprobe_comm)) current_buffer_view.data;
+       if (!kprobe_comm) {
+               ret = -1;
+               goto end;
+       }
+
+       rule = lttng_event_rule_kprobe_create();
+       if (!rule) {
+               ERR("Failed to create event rule kprobe.");
+               ret = -1;
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+
+       /* Skip to payload */
+       offset += current_buffer_view.size;
+
+       {
+               /* Map the name. */
+               struct lttng_payload_view current_payload_view =
+                               lttng_payload_view_from_view(view, offset,
+                                               kprobe_comm->name_len);
+
+               name = current_payload_view.buffer.data;
+               if (!name) {
+                       ret = -1;
+                       goto end;
+               }
+
+               if (!lttng_buffer_view_contains_string(
+                               &current_payload_view.buffer, name,
+                               kprobe_comm->name_len)) {
+                       ret = -1;
+                       goto end;
+               }
+       }
+
+       /* Skip after the name. */
+       offset += kprobe_comm->name_len;
+
+       /* Map the kernel probe location. */
+       {
+               struct lttng_payload_view current_payload_view =
+                               lttng_payload_view_from_view(view, offset,
+                                               kprobe_comm->location_len);
+
+               ret = lttng_kernel_probe_location_create_from_payload(
+                               &current_payload_view, &location);
+               if (ret < 0) {
+                       ret = -1;
+                       goto end;
+               }
+       }
+
+       if (ret != kprobe_comm->location_len) {
+               ret = -1;
+               goto end;
+       }
+
+       kprobe->location = location;
+
+       /* Skip after the location */
+       offset += kprobe_comm->location_len;
+
+       status = lttng_event_rule_kprobe_set_name(rule, name);
+       if (status != LTTNG_EVENT_RULE_STATUS_OK) {
+               ERR("Failed to set event rule kprobe name.");
+               ret = -1;
+               goto end;
+       }
+
+       *_event_rule = rule;
+       rule = NULL;
+       ret = offset;
+end:
+       lttng_event_rule_destroy(rule);
+       return ret;
+}
+
+enum lttng_event_rule_status lttng_event_rule_kprobe_set_location(
+               struct lttng_event_rule *rule,
+               const struct lttng_kernel_probe_location *location)
+{
+       struct lttng_kernel_probe_location *location_copy = NULL;
+       struct lttng_event_rule_kprobe *kprobe;
+       enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
+
+       if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !location) {
+               status = LTTNG_EVENT_RULE_STATUS_INVALID;
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+       location_copy = lttng_kernel_probe_location_copy(location);
+       if (!location_copy) {
+               status = LTTNG_EVENT_RULE_STATUS_ERROR;
+               goto end;
+       }
+
+       if (kprobe->location) {
+               lttng_kernel_probe_location_destroy(kprobe->location);
+       }
+
+       kprobe->location = location_copy;
+       location_copy = NULL;
+end:
+       lttng_kernel_probe_location_destroy(location_copy);
+       return status;
+}
+
+enum lttng_event_rule_status lttng_event_rule_kprobe_get_location(
+               const struct lttng_event_rule *rule,
+               const struct lttng_kernel_probe_location **location)
+{
+       enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
+       struct lttng_event_rule_kprobe *kprobe;
+
+       if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !location) {
+               status = LTTNG_EVENT_RULE_STATUS_INVALID;
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+       *location = kprobe->location;
+
+       if (!*location) {
+               status = LTTNG_EVENT_RULE_STATUS_UNSET;
+               goto end;
+       }
+
+end:
+       return status;
+}
+
+enum lttng_event_rule_status lttng_event_rule_kprobe_set_name(
+               struct lttng_event_rule *rule, const char *name)
+{
+       char *name_copy = NULL;
+       struct lttng_event_rule_kprobe *kprobe;
+       enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
+
+       if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !name ||
+                       strlen(name) == 0) {
+               status = LTTNG_EVENT_RULE_STATUS_INVALID;
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+       name_copy = strdup(name);
+       if (!name_copy) {
+               status = LTTNG_EVENT_RULE_STATUS_ERROR;
+               goto end;
+       }
+
+       free(kprobe->name);
+
+       kprobe->name = name_copy;
+       name_copy = NULL;
+end:
+       return status;
+}
+
+enum lttng_event_rule_status lttng_event_rule_kprobe_get_name(
+               const struct lttng_event_rule *rule, const char **name)
+{
+       struct lttng_event_rule_kprobe *kprobe;
+       enum lttng_event_rule_status status = LTTNG_EVENT_RULE_STATUS_OK;
+
+       if (!rule || !IS_KPROBE_EVENT_RULE(rule) || !name) {
+               status = LTTNG_EVENT_RULE_STATUS_INVALID;
+               goto end;
+       }
+
+       kprobe = container_of(rule, struct lttng_event_rule_kprobe, parent);
+       if (!kprobe->name) {
+               status = LTTNG_EVENT_RULE_STATUS_UNSET;
+               goto end;
+       }
+
+       *name = kprobe->name;
+end:
+       return status;
+}
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