src/bin/lttng-sessiond/notification-thread-internal.h

   1 /*
   2  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifndef NOTIFICATION_THREAD_INTERNAL_H
   9 #define NOTIFICATION_THREAD_INTERNAL_H
  10
  11 #include <common/compat/socket.h>
  12 #include <common/credentials.h>
  13 #include <common/payload.h>
  14 #include <lttng/notification/channel-internal.h>
  15 #include <lttng/ref-internal.h>
  16 #include <stdbool.h>
  17 #include <unistd.h>
  18 #include <urcu/rculfhash.h>
  19 #include <urcu/ref.h>
  20 #include <urcu/call-rcu.h>
  21 #include "notification-thread.h"
  22
  23 struct lttng_evaluation;
  24 struct notification_thread_handle;
  25
  26 struct channel_key {
  27         uint64_t key;
  28         enum lttng_domain_type domain;
  29 };
  30
  31 struct session_info {
  32         struct lttng_ref ref;
  33         char *name;
  34         uid_t uid;
  35         gid_t gid;
  36         /*
  37          * Hashtable containing back-refs (weak) to all channels in this session.
  38          * The hashtable's key is a hash of (struct channel_key) and
  39          * the value is of type (struct channel_info *).
  40          */
  41         struct cds_lfht *channel_infos_ht;
  42         struct lttng_session_trigger_list *trigger_list;
  43         /* Node in the notification thread state's sessions_ht. */
  44         struct cds_lfht_node sessions_ht_node;
  45         /*
  46          * Weak reference to the thread state's sessions_ht. Used for removal on
  47          * destruction.
  48          */
  49         struct cds_lfht *sessions_ht;
  50         uint64_t consumed_data_size;
  51         struct {
  52                 /* Whether a rotation is ongoing for this session. */
  53                 bool ongoing;
  54                 /* Identifier of the currently ongoing rotation. */
  55                 uint64_t id;
  56         } rotation;
  57         /* call_rcu delayed reclaim. */
  58         struct rcu_head rcu_node;
  59 };
  60
  61 struct channel_info {
  62         struct channel_key key;
  63         char *name;
  64         uint64_t capacity;
  65         /*
  66          * A channel info holds a reference (lttng_ref) on session_info.
  67          * session_info, in return, holds a weak reference to the channel.
  68          */
  69         struct session_info *session_info;
  70         /* Node in the notification thread state's channels_ht. */
  71         struct cds_lfht_node channels_ht_node;
  72         /* Node in the session_info's channels_ht. */
  73         struct cds_lfht_node session_info_channels_ht_node;
  74         /* call_rcu delayed reclaim. */
  75         struct rcu_head rcu_node;
  76 };
  77
  78 /*
  79  * Facilities to carry the different notifications type in the action
  80  * processing code path.
  81  */
  82 struct lttng_event_notifier_notification {
  83         uint64_t tracer_token;
  84         enum lttng_domain_type type;
  85         size_t capture_buf_size;
  86         char *capture_buffer;
  87 };
  88
  89 struct notification_client_list_element {
  90         struct notification_client *client;
  91         struct cds_list_head node;
  92 };
  93
  94 /*
  95  * Thread safety of notification_client and notification_client_list.
  96  *
  97  * The notification thread (main thread) and the action executor
  98  * interact through client lists. Hence, when the action executor
  99  * thread looks-up the list of clients subscribed to a given
 100  * condition, it will acquire a reference to the list and lock it
 101  * while attempting to communicate with the various clients.
 102  *
 103  * It is not necessary to reference-count clients as they are guaranteed
 104  * to be 'alive' if they are present in a list and that list is locked. Indeed,
 105  * removing references to the client from those subscription lists is part of
 106  * the work performed on destruction of a client.
 107  *
 108  * No provision for other access scenarios are taken into account;
 109  * this is the bare minimum to make these accesses safe and the
 110  * notification thread's state is _not_ "thread-safe" in any general
 111  * sense.
 112  */
 113 struct notification_client_list {
 114         pthread_mutex_t lock;
 115         struct urcu_ref ref;
 116         struct lttng_condition *condition;
 117         struct cds_list_head triggers_list;
 118         struct cds_list_head clients_list;
 119         /* Weak reference to container. */
 120         struct cds_lfht *notification_trigger_clients_ht;
 121         struct cds_lfht_node notification_trigger_clients_ht_node;
 122         /* call_rcu delayed reclaim. */
 123         struct rcu_head rcu_node;
 124 };
 125
 126 struct notification_client {
 127         /*
 128          * Nests within the notification_client_list lock.
 129          *
 130          * Protects the outbound communication and the active flag which
 131          * is used by both the notification and action executor threads.
 132          *
 133          * The remaining fields of the object can be used without any
 134          * synchronization as they are either immutable (id, creds, version) or
 135          * only accessed by the notification thread.
 136          */
 137         pthread_mutex_t lock;
 138         notification_client_id id;
 139         int socket;
 140         /* Client protocol version. */
 141         uint8_t major, minor;
 142         uid_t uid;
 143         gid_t gid;
 144         /*
 145          * Indicates if the credentials and versions of the client have been
 146          * checked.
 147          */
 148         bool validated;
 149         /*
 150          * Conditions to which the client's notification channel is subscribed.
 151          * List of struct lttng_condition_list_node. The condition member is
 152          * owned by the client.
 153          */
 154         struct cds_list_head condition_list;
 155         struct cds_lfht_node client_socket_ht_node;
 156         struct cds_lfht_node client_id_ht_node;
 157         struct {
 158                 /*
 159                  * If a client's communication is inactive, it means that a
 160                  * fatal error has occurred (could be either a protocol error or
 161                  * the socket API returned a fatal error). No further
 162                  * communication should be attempted; the client is queued for
 163                  * clean-up.
 164                  */
 165                 bool active;
 166                 struct {
 167                         /*
 168                          * During the reception of a message, the reception
 169                          * buffers' "size" is set to contain the current
 170                          * message's complete payload.
 171                          */
 172                         struct lttng_payload payload;
 173                         /* Bytes left to receive for the current message. */
 174                         size_t bytes_to_receive;
 175                         /* FDs left to receive for the current message. */
 176                         int fds_to_receive;
 177                         /* Type of the message being received. */
 178                         enum lttng_notification_channel_message_type msg_type;
 179                         /*
 180                          * Indicates whether or not credentials are expected
 181                          * from the client.
 182                          */
 183                         bool expect_creds;
 184                         /*
 185                          * Indicates whether or not credentials were received
 186                          * from the client.
 187                          */
 188                         bool creds_received;
 189                         /* Only used during credentials reception. */
 190                         lttng_sock_cred creds;
 191                 } inbound;
 192                 struct {
 193                         /*
 194                          * Indicates whether or not a notification addressed to
 195                          * this client was dropped because a command reply was
 196                          * already buffered.
 197                          *
 198                          * A notification is dropped whenever the buffer is not
 199                          * empty.
 200                          */
 201                         bool dropped_notification;
 202                         /*
 203                          * Indicates whether or not a command reply is already
 204                          * buffered. In this case, it means that the client is
 205                          * not consuming command replies before emitting a new
 206                          * one. This could be caused by a protocol error or a
 207                          * misbehaving/malicious client.
 208                          */
 209                         bool queued_command_reply;
 210                         struct lttng_payload payload;
 211                 } outbound;
 212         } communication;
 213         /* call_rcu delayed reclaim. */
 214         struct rcu_head rcu_node;
 215 };
 216
 217 enum client_transmission_status {
 218         CLIENT_TRANSMISSION_STATUS_COMPLETE,
 219         CLIENT_TRANSMISSION_STATUS_QUEUED,
 220         /* Communication failure. */
 221         CLIENT_TRANSMISSION_STATUS_FAIL,
 222         /* Fatal error. */
 223         CLIENT_TRANSMISSION_STATUS_ERROR,
 224 };
 225
 226 LTTNG_HIDDEN
 227 bool notification_client_list_get(struct notification_client_list *list);
 228
 229 LTTNG_HIDDEN
 230 void notification_client_list_put(struct notification_client_list *list);
 231
 232 /* Only returns a non-zero value if a fatal error occurred. */
 233 typedef int (*report_client_transmission_result_cb)(
 234                 struct notification_client *client,
 235                 enum client_transmission_status status,
 236                 void *user_data);
 237
 238 LTTNG_HIDDEN
 239 int notification_client_list_send_evaluation(
 240                 struct notification_client_list *list,
 241                 const struct lttng_trigger *trigger,
 242                 const struct lttng_evaluation *evaluation,
 243                 const struct lttng_credentials *source_object_creds,
 244                 report_client_transmission_result_cb client_report,
 245                 void *user_data);
 246
 247 LTTNG_HIDDEN
 248 int notification_thread_client_communication_update(
 249                 struct notification_thread_handle *handle,
 250                 notification_client_id id,
 251                 enum client_transmission_status transmission_status);
 252
 253 /*
 254  * Takes ownership of the payload if present.
 255  */
 256 LTTNG_HIDDEN
 257 struct lttng_event_notifier_notification *lttng_event_notifier_notification_create(
 258                 uint64_t tracer_token,
 259                 enum lttng_domain_type domain,
 260                 char *payload,
 261                 size_t payload_size);
 262
 263 LTTNG_HIDDEN
 264 void lttng_event_notifier_notification_destroy(
 265                 struct lttng_event_notifier_notification *event_notifier_notification);
 266
 267 #endif /* NOTIFICATION_THREAD_INTERNAL_H */