Docs: Clarify ominous comment wording
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index 31c3aff77d175571a44a1f0cfdc6befdb9a6c936..0c34d163841dbc35db367173174a08ad2fc5117e 100644 (file)
@@ -38,6 +38,7 @@
 #include "lttng-sessiond.h"
 #include "utils.h"
 #include "syscall.h"
+#include "agent.h"
 
 #include "cmd.h"
 
@@ -267,8 +268,7 @@ static int list_lttng_ust_global_events(char *channel_name,
 
        uchan = caa_container_of(&node->node, struct ltt_ust_channel, node.node);
 
-       nb_event += lttng_ht_get_count(uchan->events);
-
+       nb_event = lttng_ht_get_count(uchan->events);
        if (nb_event == 0) {
                ret = nb_event;
                goto error;
@@ -283,6 +283,11 @@ static int list_lttng_ust_global_events(char *channel_name,
        }
 
        cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
+               if (uevent->internal) {
+                       /* This event should remain hidden from clients */
+                       nb_event--;
+                       continue;
+               }
                strncpy(tmp[i].name, uevent->attr.name, LTTNG_SYMBOL_NAME_LEN);
                tmp[i].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
                tmp[i].enabled = uevent->enabled;
@@ -1167,23 +1172,28 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
                switch (event->type) {
                case LTTNG_EVENT_ALL:
-                       ret = event_kernel_disable_all(kchan);
+                       ret = event_kernel_disable_event_all(kchan);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
                        break;
-               case LTTNG_EVENT_TRACEPOINT:
+               case LTTNG_EVENT_TRACEPOINT:    /* fall-through */
+               case LTTNG_EVENT_SYSCALL:
                        if (!strcmp(event_name, "*")) {
-                               ret = event_kernel_disable_all_tracepoints(kchan);
+                               ret = event_kernel_disable_event_type(kchan,
+                                       event->type);
                        } else {
-                               ret = event_kernel_disable_tracepoint(kchan, event_name);
+                               ret = event_kernel_disable_event(kchan,
+                                       event_name);
                        }
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
                        break;
-               case LTTNG_EVENT_SYSCALL:
-                       ret = event_kernel_disable_syscall(kchan, event_name);
+               case LTTNG_EVENT_PROBE:
+               case LTTNG_EVENT_FUNCTION:
+               case LTTNG_EVENT_FUNCTION_ENTRY:
+                       ret = event_kernel_disable_event(kchan, event_name);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -1377,6 +1387,7 @@ static int validate_event_name(const char *name)
        int ret = 0;
        const char *c = name;
        const char *event_name_end = c + LTTNG_SYMBOL_NAME_LEN;
+       bool null_terminated = false;
 
        /*
         * Make sure that unescaped wildcards are only used as the last
@@ -1385,6 +1396,7 @@ static int validate_event_name(const char *name)
        while (c < event_name_end) {
                switch (*c) {
                case '\0':
+                       null_terminated = true;
                        goto end;
                case '\\':
                        c++;
@@ -1401,19 +1413,64 @@ static int validate_event_name(const char *name)
                c++;
        }
 end:
+       if (!ret && !null_terminated) {
+               ret = LTTNG_ERR_INVALID_EVENT_NAME;
+       }
        return ret;
 }
 
+static inline bool name_starts_with(const char *name, const char *prefix)
+{
+       const size_t max_cmp_len = min(strlen(prefix), LTTNG_SYMBOL_NAME_LEN);
+
+       return !strncmp(name, prefix, max_cmp_len);
+}
+
+/* Perform userspace-specific event name validation */
+static int validate_ust_event_name(const char *name)
+{
+       int ret = 0;
+
+       if (!name) {
+               ret = -1;
+               goto end;
+       }
+
+       /*
+        * Check name against all internal UST event component namespaces used
+        * by the agents.
+        */
+       if (name_starts_with(name, DEFAULT_JUL_EVENT_COMPONENT) ||
+               name_starts_with(name, DEFAULT_LOG4J_EVENT_COMPONENT) ||
+               name_starts_with(name, DEFAULT_PYTHON_EVENT_COMPONENT)) {
+               ret = -1;
+       }
+
+end:
+       return ret;
+}
+
+static int cmd_enable_event_internal(struct ltt_session *session,
+               struct lttng_domain *domain,
+               char *channel_name, struct lttng_event *event,
+               char *filter_expression,
+               struct lttng_filter_bytecode *filter,
+               struct lttng_event_exclusion *exclusion,
+               int wpipe);
+
 /*
- * Command LTTNG_ENABLE_EVENT processed by the client thread.
- * We own filter, exclusion, and filter_expression.
+ * Internal version of cmd_enable_event() with a supplemental
+ * "internal_event" flag which is used to enable internal events which should
+ * be hidden from clients. Such events are used in the agent implementation to
+ * enable the events through which all "agent" events are funeled.
  */
-int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
+static int _cmd_enable_event(struct ltt_session *session,
+               struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
                struct lttng_filter_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
-               int wpipe)
+               int wpipe, bool internal_event)
 {
        int ret, channel_created = 0;
        struct lttng_channel *attr;
@@ -1480,18 +1537,51 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                switch (event->type) {
                case LTTNG_EVENT_ALL:
                {
+                       char *filter_expression_a = NULL;
+                       struct lttng_filter_bytecode *filter_a = NULL;
+
+                       /*
+                        * We need to duplicate filter_expression and filter,
+                        * because ownership is passed to first enable
+                        * event.
+                        */
+                       if (filter_expression) {
+                               filter_expression_a = strdup(filter_expression);
+                               if (!filter_expression_a) {
+                                       ret = LTTNG_ERR_FATAL;
+                                       goto error;
+                               }
+                       }
+                       if (filter) {
+                               filter_a = zmalloc(sizeof(*filter_a) + filter->len);
+                               if (!filter_a) {
+                                       free(filter_expression_a);
+                                       ret = LTTNG_ERR_FATAL;
+                                       goto error;
+                               }
+                               memcpy(filter_a, filter, sizeof(*filter_a) + filter->len);
+                       }
                        event->type = LTTNG_EVENT_TRACEPOINT;   /* Hack */
-                       ret = event_kernel_enable_tracepoint(kchan, event);
+                       ret = event_kernel_enable_event(kchan, event,
+                               filter_expression, filter);
+                       /* We have passed ownership */
+                       filter_expression = NULL;
+                       filter = NULL;
                        if (ret != LTTNG_OK) {
                                if (channel_created) {
                                        /* Let's not leak a useless channel. */
                                        kernel_destroy_channel(kchan);
                                }
+                               free(filter_expression_a);
+                               free(filter_a);
                                goto error;
                        }
                        event->type = LTTNG_EVENT_SYSCALL;      /* Hack */
-                       ret = event_kernel_enable_syscall(kchan, event->name);
+                       ret = event_kernel_enable_event(kchan, event,
+                               filter_expression_a, filter_a);
                        if (ret != LTTNG_OK) {
+                               free(filter_expression_a);
+                               free(filter_a);
                                goto error;
                        }
                        break;
@@ -1500,7 +1590,11 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                case LTTNG_EVENT_FUNCTION:
                case LTTNG_EVENT_FUNCTION_ENTRY:
                case LTTNG_EVENT_TRACEPOINT:
-                       ret = event_kernel_enable_tracepoint(kchan, event);
+                       ret = event_kernel_enable_event(kchan, event,
+                               filter_expression, filter);
+                       /* We have passed ownership */
+                       filter_expression = NULL;
+                       filter = NULL;
                        if (ret != LTTNG_OK) {
                                if (channel_created) {
                                        /* Let's not leak a useless channel. */
@@ -1510,7 +1604,11 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                        }
                        break;
                case LTTNG_EVENT_SYSCALL:
-                       ret = event_kernel_enable_syscall(kchan, event->name);
+                       ret = event_kernel_enable_event(kchan, event,
+                               filter_expression, filter);
+                       /* We have passed ownership */
+                       filter_expression = NULL;
+                       filter = NULL;
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -1566,9 +1664,25 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                        assert(uchan);
                }
 
+               if (!internal_event) {
+                       /*
+                        * Ensure the event name is not reserved for internal
+                        * use.
+                        */
+                       ret = validate_ust_event_name(event->name);
+                       if (ret) {
+                               WARN("Userspace event name %s failed validation.",
+                                               event->name ?
+                                               event->name : "NULL");
+                               ret = LTTNG_ERR_INVALID_EVENT_NAME;
+                               goto error;
+                       }
+               }
+
                /* At this point, the session and channel exist on the tracer */
                ret = event_ust_enable_tracepoint(usess, uchan, event,
-                               filter_expression, filter, exclusion);
+                               filter_expression, filter, exclusion,
+                               internal_event);
                /* We have passed ownership */
                filter_expression = NULL;
                filter = NULL;
@@ -1631,7 +1745,7 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                        default_chan_name = DEFAULT_PYTHON_CHANNEL_NAME;
                        break;
                default:
-                       /* The switch/case we are in should avoid this else big problem */
+                       /* The switch/case we are in makes this impossible */
                        assert(0);
                }
 
@@ -1651,7 +1765,7 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
                                        + filter->len);
                        }
 
-                       ret = cmd_enable_event(session, &tmp_dom,
+                       ret = cmd_enable_event_internal(session, &tmp_dom,
                                        (char *) default_chan_name,
                                        &uevent, filter_expression, filter_copy,
                                        NULL, wpipe);
@@ -1692,6 +1806,38 @@ error:
        return ret;
 }
 
+/*
+ * Command LTTNG_ENABLE_EVENT processed by the client thread.
+ * We own filter, exclusion, and filter_expression.
+ */
+int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
+               char *channel_name, struct lttng_event *event,
+               char *filter_expression,
+               struct lttng_filter_bytecode *filter,
+               struct lttng_event_exclusion *exclusion,
+               int wpipe)
+{
+       return _cmd_enable_event(session, domain, channel_name, event,
+                       filter_expression, filter, exclusion, wpipe, false);
+}
+
+/*
+ * Enable an event which is internal to LTTng. An internal should
+ * never be made visible to clients and are immune to checks such as
+ * reserved names.
+ */
+static int cmd_enable_event_internal(struct ltt_session *session,
+               struct lttng_domain *domain,
+               char *channel_name, struct lttng_event *event,
+               char *filter_expression,
+               struct lttng_filter_bytecode *filter,
+               struct lttng_event_exclusion *exclusion,
+               int wpipe)
+{
+       return _cmd_enable_event(session, domain, channel_name, event,
+                       filter_expression, filter, exclusion, wpipe, true);
+}
+
 /*
  * Command LTTNG_LIST_TRACEPOINTS processed by the client thread.
  */
@@ -1851,9 +1997,7 @@ int cmd_start_trace(struct ltt_session *session)
         * possible to enable channel thus inform the client.
         */
        if (usess && usess->domain_global.channels) {
-               rcu_read_lock();
                nb_chan += lttng_ht_get_count(usess->domain_global.channels);
-               rcu_read_unlock();
        }
        if (ksession) {
                nb_chan += ksession->channel_count;
@@ -2410,6 +2554,10 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 
        if (session->kernel_session != NULL) {
                (*domains)[index].type = LTTNG_DOMAIN_KERNEL;
+
+               /* Kernel session buffer type is always GLOBAL */
+               (*domains)[index].buf_type = LTTNG_BUFFER_GLOBAL;
+
                index++;
        }
 
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