Fix: sessiond: double free on duplicate removal of tracer source
[lttng-tools.git] / src / bin / lttng-sessiond / notification-thread-events.c
index e01a00538ba8d2f04c389086860ebfd933798e9f..212746faa1c7a50d67e3006f868908222a00d22c 100644 (file)
 #include <lttng/condition/buffer-usage-internal.h>
 #include <lttng/condition/session-consumed-size-internal.h>
 #include <lttng/condition/session-rotation-internal.h>
+#include <lttng/condition/event-rule-internal.h>
+#include <lttng/domain-internal.h>
 #include <lttng/notification/channel-internal.h>
+#include <lttng/trigger/trigger-internal.h>
+#include <lttng/event-rule/event-rule-internal.h>
 
 #include <time.h>
 #include <unistd.h>
@@ -34,6 +38,7 @@
 #include <inttypes.h>
 #include <fcntl.h>
 
+#include "condition-internal.h"
 #include "notification-thread.h"
 #include "notification-thread-events.h"
 #include "notification-thread-commands.h"
@@ -110,6 +115,7 @@ struct lttng_session_trigger_list {
 struct lttng_trigger_ht_element {
        struct lttng_trigger *trigger;
        struct cds_lfht_node node;
+       struct cds_lfht_node node_by_name_uid;
        /* call_rcu delayed reclaim. */
        struct rcu_head rcu_node;
 };
@@ -187,6 +193,9 @@ int client_handle_transmission_status(
                enum client_transmission_status transmission_status,
                struct notification_thread_state *state);
 
+static
+void free_lttng_trigger_ht_element_rcu(struct rcu_head *node);
+
 static
 int match_client_socket(struct cds_lfht_node *node, const void *key)
 {
@@ -261,18 +270,26 @@ int match_channel_info(struct cds_lfht_node *node, const void *key)
 }
 
 static
-int match_condition(struct cds_lfht_node *node, const void *key)
+int match_trigger(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_condition *condition_key = (struct lttng_condition *) key;
-       struct lttng_trigger_ht_element *trigger;
-       struct lttng_condition *condition;
+       struct lttng_trigger *trigger_key = (struct lttng_trigger *) key;
+       struct lttng_trigger_ht_element *trigger_ht_element;
 
-       trigger = caa_container_of(node, struct lttng_trigger_ht_element,
+       trigger_ht_element = caa_container_of(node, struct lttng_trigger_ht_element,
                        node);
-       condition = lttng_trigger_get_condition(trigger->trigger);
-       assert(condition);
 
-       return !!lttng_condition_is_equal(condition_key, condition);
+       return !!lttng_trigger_is_equal(trigger_key, trigger_ht_element->trigger);
+}
+
+static
+int match_trigger_token(struct cds_lfht_node *node, const void *key)
+{
+       const uint64_t *_key = key;
+       struct notification_trigger_tokens_ht_element *element;
+
+       element = caa_container_of(node,
+                       struct notification_trigger_tokens_ht_element, node);
+       return *_key == element->token;
 }
 
 static
@@ -301,105 +318,71 @@ int match_session(struct cds_lfht_node *node, const void *key)
        return !strcmp(session_info->name, name);
 }
 
+/*
+ * Match trigger based on name and credentials only.
+ * Name duplication is NOT allowed for the same uid.
+ */
 static
-unsigned long lttng_condition_buffer_usage_hash(
-       const struct lttng_condition *_condition)
+int match_trigger_by_name_uid(struct cds_lfht_node *node,
+               const void *key)
 {
-       unsigned long hash;
-       unsigned long condition_type;
-       struct lttng_condition_buffer_usage *condition;
-
-       condition = container_of(_condition,
-                       struct lttng_condition_buffer_usage, parent);
-
-       condition_type = (unsigned long) condition->parent.type;
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       if (condition->session_name) {
-               hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
-       }
-       if (condition->channel_name) {
-               hash ^= hash_key_str(condition->channel_name, lttng_ht_seed);
-       }
-       if (condition->domain.set) {
-               hash ^= hash_key_ulong(
-                               (void *) condition->domain.type,
-                               lttng_ht_seed);
+       bool match = false;
+       const char *name;
+       const char *key_name;
+       enum lttng_trigger_status status;
+       const struct lttng_credentials *key_creds;
+       const struct lttng_credentials *node_creds;
+       const struct lttng_trigger *trigger_key =
+                       (const struct lttng_trigger *) key;
+       const struct lttng_trigger_ht_element *trigger_ht_element =
+                       caa_container_of(node,
+                               struct lttng_trigger_ht_element,
+                               node_by_name_uid);
+
+       status = lttng_trigger_get_name(trigger_ht_element->trigger, &name);
+       assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+       status = lttng_trigger_get_name(trigger_key, &key_name);
+       assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+       /* Compare the names. */
+       if (strcmp(name, key_name) != 0) {
+               goto end;
        }
-       if (condition->threshold_ratio.set) {
-               uint64_t val;
 
-               val = condition->threshold_ratio.value * (double) UINT32_MAX;
-               hash ^= hash_key_u64(&val, lttng_ht_seed);
-       } else if (condition->threshold_bytes.set) {
-               uint64_t val;
+       /* Compare the owners' UIDs. */
+       key_creds = lttng_trigger_get_credentials(trigger_key);
+       node_creds = lttng_trigger_get_credentials(trigger_ht_element->trigger);
 
-               val = condition->threshold_bytes.value;
-               hash ^= hash_key_u64(&val, lttng_ht_seed);
-       }
-       return hash;
+       match = lttng_credentials_is_equal_uid(key_creds, node_creds);
+
+end:
+       return match;
 }
 
+/*
+ * Hash trigger based on name and credentials only.
+ */
 static
-unsigned long lttng_condition_session_consumed_size_hash(
-       const struct lttng_condition *_condition)
+unsigned long hash_trigger_by_name_uid(const struct lttng_trigger *trigger)
 {
-       unsigned long hash;
-       unsigned long condition_type =
-                       (unsigned long) LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE;
-       struct lttng_condition_session_consumed_size *condition;
-       uint64_t val;
+       unsigned long hash = 0;
+       const struct lttng_credentials *trigger_creds;
+       const char *trigger_name;
+       enum lttng_trigger_status status;
 
-       condition = container_of(_condition,
-                       struct lttng_condition_session_consumed_size, parent);
-
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       if (condition->session_name) {
-               hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
+       status = lttng_trigger_get_name(trigger, &trigger_name);
+       if (status == LTTNG_TRIGGER_STATUS_OK) {
+               hash = hash_key_str(trigger_name, lttng_ht_seed);
        }
-       val = condition->consumed_threshold_bytes.value;
-       hash ^= hash_key_u64(&val, lttng_ht_seed);
-       return hash;
-}
 
-static
-unsigned long lttng_condition_session_rotation_hash(
-       const struct lttng_condition *_condition)
-{
-       unsigned long hash, condition_type;
-       struct lttng_condition_session_rotation *condition;
+       trigger_creds = lttng_trigger_get_credentials(trigger);
+       hash ^= hash_key_ulong((void *) (unsigned long) LTTNG_OPTIONAL_GET(trigger_creds->uid),
+                       lttng_ht_seed);
 
-       condition = container_of(_condition,
-                       struct lttng_condition_session_rotation, parent);
-       condition_type = (unsigned long) condition->parent.type;
-       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
-       assert(condition->session_name);
-       hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
        return hash;
 }
 
-/*
- * The lttng_condition hashing code is kept in this file (rather than
- * condition.c) since it makes use of GPLv2 code (hashtable utils), which we
- * don't want to link in liblttng-ctl.
- */
-static
-unsigned long lttng_condition_hash(const struct lttng_condition *condition)
-{
-       switch (condition->type) {
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
-               return lttng_condition_buffer_usage_hash(condition);
-       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
-               return lttng_condition_session_consumed_size_hash(condition);
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
-       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
-               return lttng_condition_session_rotation_hash(condition);
-       default:
-               ERR("[notification-thread] Unexpected condition type caught");
-               abort();
-       }
-}
-
 static
 unsigned long hash_channel_key(struct channel_key *key)
 {
@@ -442,6 +425,8 @@ enum lttng_object_type get_condition_binding_object(
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
        case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
                return LTTNG_OBJECT_TYPE_SESSION;
+       case LTTNG_CONDITION_TYPE_EVENT_RULE_HIT:
+               return LTTNG_OBJECT_TYPE_NONE;
        default:
                return LTTNG_OBJECT_TYPE_UNKNOWN;
        }
@@ -952,6 +937,7 @@ int evaluate_condition_for_client(const struct lttng_trigger *trigger,
                                &evaluation, &object_uid, &object_gid);
                break;
        case LTTNG_OBJECT_TYPE_NONE:
+               DBG("[notification-thread] Newly subscribed-to condition not bound to object, nothing to evaluate");
                ret = 0;
                goto end;
        case LTTNG_OBJECT_TYPE_UNKNOWN:
@@ -1807,8 +1793,8 @@ int handle_notification_thread_command_session_rotation(
        struct lttng_trigger_list_element *trigger_list_element;
        struct session_info *session_info;
        const struct lttng_credentials session_creds = {
-               .uid = session_uid,
-               .gid = session_gid,
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(session_uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(session_gid),
        };
 
        rcu_read_lock();
@@ -1918,25 +1904,198 @@ end:
 }
 
 static
-int condition_is_supported(struct lttng_condition *condition)
+int handle_notification_thread_command_add_tracer_event_source(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd,
+               enum lttng_domain_type domain_type,
+               enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct notification_event_tracer_event_source_element *element = NULL;
+
+       element = zmalloc(sizeof(*element));
+       if (!element) {
+               cmd_result = LTTNG_ERR_NOMEM;
+               ret = -1;
+               goto end;
+       }
+
+       element->fd = tracer_event_source_fd;
+       element->domain = domain_type;
+
+       cds_list_add(&element->node, &state->tracer_event_sources_list);
+
+       DBG3("[notification-thread] Adding tracer event source fd to poll set: tracer_event_source_fd = %d, domain = '%s'",
+                       tracer_event_source_fd,
+                       lttng_domain_type_str(domain_type));
+
+       /* Adding the read side pipe to the event poll. */
+       ret = lttng_poll_add(&state->events, tracer_event_source_fd, LPOLLIN | LPOLLERR);
+       if (ret < 0) {
+               ERR("[notification-thread] Failed to add tracer event source to poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(element->domain));
+               cds_list_del(&element->node);
+               free(element);
+               goto end;
+       }
+
+       element->is_fd_in_poll_set = true;
+
+end:
+       *_cmd_result = cmd_result;
+       return ret;
+}
+
+static
+int handle_notification_thread_command_remove_tracer_event_source(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd,
+               enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       bool found = false;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct notification_event_tracer_event_source_element *source_element = NULL, *tmp;
+
+       cds_list_for_each_entry_safe(source_element, tmp,
+                       &state->tracer_event_sources_list, node) {
+               if (source_element->fd != tracer_event_source_fd) {
+                       continue;
+               }
+
+               DBG("[notification-thread] Removed tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(source_element->domain));
+               cds_list_del(&source_element->node);
+               found = true;
+               break;
+       }
+
+       if (!found) {
+               /*
+                * This is temporarily allowed since the poll activity set is
+                * not properly cleaned-up for the moment. This is adressed in
+                * an upcoming fix.
+                */
+               source_element = NULL;
+               goto end;
+       }
+
+       if (!source_element->is_fd_in_poll_set) {
+               /* Skip the poll set removal. */
+               goto end;
+       }
+
+       DBG3("[notification-thread] Removing tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                       tracer_event_source_fd,
+                       lttng_domain_type_str(source_element->domain));
+
+       /* Removing the fd from the event poll set. */
+       ret = lttng_poll_del(&state->events, tracer_event_source_fd);
+       if (ret < 0) {
+               ERR("[notification-thread] Failed to remove tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+                               tracer_event_source_fd,
+                               lttng_domain_type_str(source_element->domain));
+               cmd_result = LTTNG_ERR_FATAL;
+               goto end;
+       }
+
+       source_element->is_fd_in_poll_set = false;
+
+end:
+       free(source_element);
+       *_cmd_result = cmd_result;
+       return ret;
+}
+
+int handle_notification_thread_remove_tracer_event_source_no_result(
+               struct notification_thread_state *state,
+               int tracer_event_source_fd)
 {
        int ret;
+       enum lttng_error_code cmd_result;
+
+       ret = handle_notification_thread_command_remove_tracer_event_source(
+                       state, tracer_event_source_fd, &cmd_result);
+       (void) cmd_result;
+       return ret;
+}
+
+static int handle_notification_thread_command_list_triggers(
+               struct notification_thread_handle *handle,
+               struct notification_thread_state *state,
+               uid_t client_uid,
+               struct lttng_triggers **triggers,
+               enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct cds_lfht_iter iter;
+       struct lttng_trigger_ht_element *trigger_ht_element;
+       struct lttng_triggers *local_triggers = NULL;
+       const struct lttng_credentials *creds;
+
+       rcu_read_lock();
+
+       local_triggers = lttng_triggers_create();
+       if (!local_triggers) {
+               /* Not a fatal error. */
+               cmd_result = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       cds_lfht_for_each_entry(state->triggers_ht, &iter,
+                       trigger_ht_element, node) {
+               /*
+                * Only return the triggers to which the client has access.
+                * The root user has visibility over all triggers.
+                */
+               creds = lttng_trigger_get_credentials(trigger_ht_element->trigger);
+               if (client_uid != lttng_credentials_get_uid(creds) && client_uid != 0) {
+                       continue;
+               }
+
+               ret = lttng_triggers_add(local_triggers,
+                               trigger_ht_element->trigger);
+               if (ret < 0) {
+                       /* Not a fatal error. */
+                       ret = 0;
+                       cmd_result = LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+       }
+
+       /* Transferring ownership to the caller. */
+       *triggers = local_triggers;
+       local_triggers = NULL;
+
+end:
+       rcu_read_unlock();
+       lttng_triggers_destroy(local_triggers);
+       *_cmd_result = cmd_result;
+       return ret;
+}
+
+static
+bool condition_is_supported(struct lttng_condition *condition)
+{
+       bool is_supported;
 
        switch (lttng_condition_get_type(condition)) {
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
        {
+               int ret;
                enum lttng_domain_type domain;
 
                ret = lttng_condition_buffer_usage_get_domain_type(condition,
                                &domain);
-               if (ret) {
-                       ret = -1;
-                       goto end;
-               }
+               assert(ret == 0);
 
                if (domain != LTTNG_DOMAIN_KERNEL) {
-                       ret = 1;
+                       is_supported = true;
                        goto end;
                }
 
@@ -1944,15 +2103,43 @@ int condition_is_supported(struct lttng_condition *condition)
                 * Older kernel tracers don't expose the API to monitor their
                 * buffers. Therefore, we reject triggers that require that
                 * mechanism to be available to be evaluated.
+                *
+                * Assume unsupported on error.
+                */
+               is_supported = kernel_supports_ring_buffer_snapshot_sample_positions() == 1;
+               break;
+       }
+       case LTTNG_CONDITION_TYPE_EVENT_RULE_HIT:
+       {
+               const struct lttng_event_rule *event_rule;
+               enum lttng_domain_type domain;
+               const enum lttng_condition_status status =
+                               lttng_condition_event_rule_get_rule(
+                                               condition, &event_rule);
+
+               assert(status == LTTNG_CONDITION_STATUS_OK);
+
+               domain = lttng_event_rule_get_domain_type(event_rule);
+               if (domain != LTTNG_DOMAIN_KERNEL) {
+                       is_supported = true;
+                       goto end;
+               }
+
+               /*
+                * Older kernel tracers can't emit notification. Therefore, we
+                * reject triggers that require that mechanism to be available
+                * to be evaluated.
+                *
+                * Assume unsupported on error.
                 */
-               ret = kernel_supports_ring_buffer_snapshot_sample_positions();
+               is_supported = kernel_supports_event_notifiers() == 1;
                break;
        }
        default:
-               ret = 1;
+               is_supported = true;
        }
 end:
-       return ret;
+       return is_supported;
 }
 
 /* Must be called with RCU read lock held. */
@@ -2085,6 +2272,50 @@ end:
        return is_notify;
 }
 
+static bool trigger_name_taken(struct notification_thread_state *state,
+               const struct lttng_trigger *trigger)
+{
+       struct cds_lfht_iter iter;
+
+       /*
+        * No duplicata is allowed in the triggers_by_name_uid_ht.
+        * The match is done against the trigger name and uid.
+        */
+       cds_lfht_lookup(state->triggers_by_name_uid_ht,
+                       hash_trigger_by_name_uid(trigger),
+                       match_trigger_by_name_uid,
+                       trigger,
+                       &iter);
+       return !!cds_lfht_iter_get_node(&iter);
+}
+
+static
+enum lttng_error_code generate_trigger_name(
+               struct notification_thread_state *state,
+               struct lttng_trigger *trigger, const char **name)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       bool taken = false;
+       enum lttng_trigger_status status;
+
+       do {
+               const int ret = lttng_trigger_generate_name(trigger,
+                               state->trigger_id.name_offset++);
+               if (ret) {
+                       /* The only reason this can fail right now. */
+                       ret_code = LTTNG_ERR_NOMEM;
+                       break;
+               }
+
+               status = lttng_trigger_get_name(trigger, name);
+               assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+               taken = trigger_name_taken(state, trigger);
+       } while (taken || state->trigger_id.name_offset == UINT64_MAX);
+
+       return ret_code;
+}
+
 /*
  * FIXME A client's credentials are not checked when registering a trigger.
  *
@@ -2112,27 +2343,49 @@ int handle_notification_thread_command_register_trigger(
        struct notification_client_list *client_list = NULL;
        struct lttng_trigger_ht_element *trigger_ht_element = NULL;
        struct notification_client_list_element *client_list_element;
+       struct notification_trigger_tokens_ht_element *trigger_tokens_ht_element = NULL;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
+       const char* trigger_name;
        bool free_trigger = true;
        struct lttng_evaluation *evaluation = NULL;
        struct lttng_credentials object_creds;
+       uid_t object_uid;
+       gid_t object_gid;
        enum action_executor_status executor_status;
+       const uint64_t trigger_tracer_token =
+                       state->trigger_id.next_tracer_token++;
 
        rcu_read_lock();
 
+       /* Set the trigger's tracer token. */
+       lttng_trigger_set_tracer_token(trigger, trigger_tracer_token);
+
+       if (lttng_trigger_get_name(trigger, &trigger_name) ==
+                       LTTNG_TRIGGER_STATUS_UNSET) {
+               const enum lttng_error_code ret_code = generate_trigger_name(
+                               state, trigger, &trigger_name);
+
+               if (ret_code != LTTNG_OK) {
+                       /* Fatal error. */
+                       ret = -1;
+                       *cmd_result = ret_code;
+                       goto error;
+               }
+       } else if (trigger_name_taken(state, trigger)) {
+               /* Not a fatal error. */
+               *cmd_result = LTTNG_ERR_TRIGGER_EXISTS;
+               ret = 0;
+               goto error;
+       }
+
        condition = lttng_trigger_get_condition(trigger);
        assert(condition);
 
-       ret = condition_is_supported(condition);
-       if (ret < 0) {
-               goto error;
-       } else if (ret == 0) {
+       /* Some conditions require tracers to implement a minimal ABI version. */
+       if (!condition_is_supported(condition)) {
                *cmd_result = LTTNG_ERR_NOT_SUPPORTED;
                goto error;
-       } else {
-               /* Feature is supported, continue. */
-               ret = 0;
        }
 
        trigger_ht_element = zmalloc(sizeof(*trigger_ht_element));
@@ -2143,12 +2396,13 @@ int handle_notification_thread_command_register_trigger(
 
        /* Add trigger to the trigger_ht. */
        cds_lfht_node_init(&trigger_ht_element->node);
+       cds_lfht_node_init(&trigger_ht_element->node_by_name_uid);
        trigger_ht_element->trigger = trigger;
 
        node = cds_lfht_add_unique(state->triggers_ht,
                        lttng_condition_hash(condition),
-                       match_condition,
-                       condition,
+                       match_trigger,
+                       trigger,
                        &trigger_ht_element->node);
        if (node != &trigger_ht_element->node) {
                /* Not a fatal error, simply report it to the client. */
@@ -2156,10 +2410,59 @@ int handle_notification_thread_command_register_trigger(
                goto error_free_ht_element;
        }
 
+       node = cds_lfht_add_unique(state->triggers_by_name_uid_ht,
+                       hash_trigger_by_name_uid(trigger),
+                       match_trigger_by_name_uid,
+                       trigger,
+                       &trigger_ht_element->node_by_name_uid);
+       if (node != &trigger_ht_element->node_by_name_uid) {
+               /* Not a fatal error, simply report it to the client. */
+               cds_lfht_del(state->triggers_ht, &trigger_ht_element->node);
+               *cmd_result = LTTNG_ERR_TRIGGER_EXISTS;
+               goto error_free_ht_element;
+       }
+
+       if (lttng_condition_get_type(condition) == LTTNG_CONDITION_TYPE_EVENT_RULE_HIT) {
+               trigger_tokens_ht_element = zmalloc(sizeof(*trigger_tokens_ht_element));
+               if (!trigger_tokens_ht_element) {
+                       /* Fatal error. */
+                       ret = -1;
+                       cds_lfht_del(state->triggers_ht,
+                                       &trigger_ht_element->node);
+                       cds_lfht_del(state->triggers_by_name_uid_ht,
+                                       &trigger_ht_element->node_by_name_uid);
+                       goto error_free_ht_element;
+               }
+
+               /* Add trigger token to the trigger_tokens_ht. */
+               cds_lfht_node_init(&trigger_tokens_ht_element->node);
+               trigger_tokens_ht_element->token =
+                               LTTNG_OPTIONAL_GET(trigger->tracer_token);
+               trigger_tokens_ht_element->trigger = trigger;
+
+               node = cds_lfht_add_unique(state->trigger_tokens_ht,
+                               hash_key_u64(&trigger_tokens_ht_element->token,
+                                               lttng_ht_seed),
+                               match_trigger_token,
+                               &trigger_tokens_ht_element->token,
+                               &trigger_tokens_ht_element->node);
+               if (node != &trigger_tokens_ht_element->node) {
+                       /* Internal corruption, fatal error. */
+                       ret = -1;
+                       *cmd_result = LTTNG_ERR_TRIGGER_EXISTS;
+                       cds_lfht_del(state->triggers_ht,
+                                       &trigger_ht_element->node);
+                       cds_lfht_del(state->triggers_by_name_uid_ht,
+                                       &trigger_ht_element->node_by_name_uid);
+                       goto error_free_ht_element;
+               }
+       }
+
        /*
         * Ownership of the trigger and of its wrapper was transfered to
-        * the triggers_ht.
+        * the triggers_ht. Same for token ht element if necessary.
         */
+       trigger_tokens_ht_element = NULL;
        trigger_ht_element = NULL;
        free_trigger = false;
 
@@ -2260,21 +2563,21 @@ int handle_notification_thread_command_register_trigger(
        switch (get_condition_binding_object(condition)) {
        case LTTNG_OBJECT_TYPE_SESSION:
                ret = evaluate_session_condition_for_client(condition, state,
-                               &evaluation, &object_creds.uid,
-                               &object_creds.gid);
+                               &evaluation, &object_uid,
+                               &object_gid);
                break;
        case LTTNG_OBJECT_TYPE_CHANNEL:
                ret = evaluate_channel_condition_for_client(condition, state,
-                               &evaluation, &object_creds.uid,
-                               &object_creds.gid);
+                               &evaluation, &object_uid,
+                               &object_gid);
                break;
        case LTTNG_OBJECT_TYPE_NONE:
                ret = 0;
-               goto error_put_client_list;
+               break;
        case LTTNG_OBJECT_TYPE_UNKNOWN:
        default:
                ret = -1;
-               goto error_put_client_list;
+               break;
        }
 
        if (ret) {
@@ -2282,12 +2585,15 @@ int handle_notification_thread_command_register_trigger(
                goto error_put_client_list;
        }
 
+       LTTNG_OPTIONAL_SET(&object_creds.uid, object_uid);
+       LTTNG_OPTIONAL_SET(&object_creds.gid, object_gid);
+
        DBG("Newly registered trigger's condition evaluated to %s",
                        evaluation ? "true" : "false");
        if (!evaluation) {
                /* Evaluation yielded nothing. Normal exit. */
                ret = 0;
-               goto error_put_client_list;
+               goto end;
        }
 
        /*
@@ -2318,18 +2624,27 @@ int handle_notification_thread_command_register_trigger(
                 */
                WARN("No space left when enqueuing action associated to newly registered trigger");
                ret = 0;
-               goto error_put_client_list;
+               goto end;
        default:
                abort();
        }
 
+end:
        *cmd_result = LTTNG_OK;
+       DBG("Registered trigger: name = `%s`, tracer token = %" PRIu64,
+                       trigger_name, trigger_tracer_token);
 
 error_put_client_list:
        notification_client_list_put(client_list);
 
 error_free_ht_element:
-       free(trigger_ht_element);
+       if (trigger_ht_element) {
+               /* Delayed removal due to RCU constraint on delete. */
+               call_rcu(&trigger_ht_element->rcu_node,
+                               free_lttng_trigger_ht_element_rcu);
+       }
+
+       free(trigger_tokens_ht_element);
 error:
        if (free_trigger) {
                lttng_trigger_destroy(trigger);
@@ -2345,6 +2660,13 @@ void free_lttng_trigger_ht_element_rcu(struct rcu_head *node)
                        rcu_node));
 }
 
+static
+void free_notification_trigger_tokens_ht_element_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_trigger_tokens_ht_element,
+                       rcu_node));
+}
+
 static
 int handle_notification_thread_command_unregister_trigger(
                struct notification_thread_state *state,
@@ -2364,8 +2686,8 @@ int handle_notification_thread_command_unregister_trigger(
 
        cds_lfht_lookup(state->triggers_ht,
                        lttng_condition_hash(condition),
-                       match_condition,
-                       condition,
+                       match_trigger,
+                       trigger,
                        &iter);
        triggers_ht_node = cds_lfht_iter_get_node(&iter);
        if (!triggers_ht_node) {
@@ -2382,13 +2704,7 @@ int handle_notification_thread_command_unregister_trigger(
 
                cds_list_for_each_entry_safe(trigger_element, tmp,
                                &trigger_list->list, node) {
-                       const struct lttng_condition *current_condition =
-                                       lttng_trigger_get_const_condition(
-                                               trigger_element->trigger);
-
-                       assert(current_condition);
-                       if (!lttng_condition_is_equal(condition,
-                                       current_condition)) {
+                       if (!lttng_trigger_is_equal(trigger, trigger_element->trigger)) {
                                continue;
                        }
 
@@ -2399,21 +2715,46 @@ int handle_notification_thread_command_unregister_trigger(
                }
        }
 
-       /*
-        * Remove and release the client list from
-        * notification_trigger_clients_ht.
-        */
-       client_list = get_client_list_from_condition(state, condition);
-       assert(client_list);
+       if (lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_EVENT_RULE_HIT) {
+               struct notification_trigger_tokens_ht_element
+                               *trigger_tokens_ht_element;
 
-       /* Put new reference and the hashtable's reference. */
-       notification_client_list_put(client_list);
-       notification_client_list_put(client_list);
-       client_list = NULL;
+               cds_lfht_for_each_entry (state->trigger_tokens_ht, &iter,
+                               trigger_tokens_ht_element, node) {
+                       if (!lttng_trigger_is_equal(trigger,
+                                           trigger_tokens_ht_element->trigger)) {
+                               continue;
+                       }
+
+                       DBG("[notification-thread] Removed trigger from tokens_ht");
+                       cds_lfht_del(state->trigger_tokens_ht,
+                                       &trigger_tokens_ht_element->node);
+                       call_rcu(&trigger_tokens_ht_element->rcu_node,
+                                       free_notification_trigger_tokens_ht_element_rcu);
+
+                       break;
+               }
+       }
+
+       if (is_trigger_action_notify(trigger)) {
+               /*
+                * Remove and release the client list from
+                * notification_trigger_clients_ht.
+                */
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
+
+               /* Put new reference and the hashtable's reference. */
+               notification_client_list_put(client_list);
+               notification_client_list_put(client_list);
+               client_list = NULL;
+       }
 
        /* Remove trigger from triggers_ht. */
        trigger_ht_element = caa_container_of(triggers_ht_node,
                        struct lttng_trigger_ht_element, node);
+       cds_lfht_del(state->triggers_by_name_uid_ht, &trigger_ht_element->node_by_name_uid);
        cds_lfht_del(state->triggers_ht, triggers_ht_node);
 
        /* Release the ownership of the trigger. */
@@ -2496,6 +2837,33 @@ int handle_notification_thread_command(
                                cmd->parameters.session_rotation.location,
                                &cmd->reply_code);
                break;
+       case NOTIFICATION_COMMAND_TYPE_ADD_TRACER_EVENT_SOURCE:
+               ret = handle_notification_thread_command_add_tracer_event_source(
+                               state,
+                               cmd->parameters.tracer_event_source.tracer_event_source_fd,
+                               cmd->parameters.tracer_event_source.domain,
+                               &cmd->reply_code);
+               break;
+       case NOTIFICATION_COMMAND_TYPE_REMOVE_TRACER_EVENT_SOURCE:
+               ret = handle_notification_thread_command_remove_tracer_event_source(
+                               state,
+                               cmd->parameters.tracer_event_source.tracer_event_source_fd,
+                               &cmd->reply_code);
+               break;
+       case NOTIFICATION_COMMAND_TYPE_LIST_TRIGGERS:
+       {
+               struct lttng_triggers *triggers = NULL;
+
+               ret = handle_notification_thread_command_list_triggers(
+                               handle,
+                               state,
+                               cmd->parameters.list_triggers.uid,
+                               &triggers,
+                               &cmd->reply_code);
+               cmd->reply.list_triggers.triggers = triggers;
+               ret = 0;
+               break;
+       }
        case NOTIFICATION_COMMAND_TYPE_QUIT:
                DBG("[notification-thread] Received quit command");
                cmd->reply_code = LTTNG_OK;
@@ -3582,11 +3950,15 @@ int send_evaluation_to_clients(const struct lttng_trigger *trigger,
                struct notification_thread_state *state,
                uid_t object_uid, gid_t object_gid)
 {
+       const struct lttng_credentials creds = {
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(object_uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(object_gid),
+       };
+
        return notification_client_list_send_evaluation(client_list,
                        lttng_trigger_get_const_condition(trigger), evaluation,
                        lttng_trigger_get_credentials(trigger),
-                       &(struct lttng_credentials){
-                                       .uid = object_uid, .gid = object_gid},
+                       &creds,
                        client_handle_transmission_status_wrapper, state);
 }
 
@@ -3693,8 +4065,8 @@ int notification_client_list_send_evaluation(
                }
 
                if (source_object_creds) {
-                       if (client->uid != source_object_creds->uid &&
-                                       client->gid != source_object_creds->gid &&
+                       if (client->uid != lttng_credentials_get_uid(source_object_creds) &&
+                                       client->gid != lttng_credentials_get_gid(source_object_creds) &&
                                        client->uid != 0) {
                                /*
                                 * Client is not allowed to monitor this
@@ -3705,7 +4077,7 @@ int notification_client_list_send_evaluation(
                        }
                }
 
-               if (client->uid != trigger_creds->uid && client->gid != trigger_creds->gid) {
+               if (client->uid != lttng_credentials_get_uid(trigger_creds) && client->gid != lttng_credentials_get_gid(trigger_creds)) {
                        DBG("[notification-thread] Skipping client at it does not have the permission to receive notification for this trigger");
                        goto skip_client;
                }
@@ -3894,8 +4266,8 @@ int handle_notification_thread_channel_sample(
        }
 
        channel_creds = (typeof(channel_creds)) {
-               .uid = channel_info->session_info->uid,
-               .gid = channel_info->session_info->gid,
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(channel_info->session_info->uid),
+               .gid = LTTNG_OPTIONAL_INIT_VALUE(channel_info->session_info->gid),
        };
 
        trigger_list = caa_container_of(node, struct lttng_channel_trigger_list,
@@ -3933,6 +4305,12 @@ int handle_notification_thread_channel_sample(
                        goto put_list;
                }
 
+               if (!lttng_trigger_should_fire(trigger)) {
+                       goto put_list;
+               }
+
+               lttng_trigger_fire(trigger);
+
                /*
                 * Ownership of `evaluation` transferred to the action executor
                 * no matter the result.
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