#include <sys/types.h>
#include <sys/socket.h>
+#include <sys/prctl.h>
#include <unistd.h>
#include <errno.h>
-#include <ust/lttng-ust-abi.h>
-#include <lttng-ust-comm.h>
-#include <ust/usterr-signal-safe.h>
#include <pthread.h>
+#include <semaphore.h>
+#include <time.h>
#include <assert.h>
+#include <signal.h>
+#include <urcu/uatomic.h>
+
+#include <lttng-ust-comm.h>
+#include <ust/usterr-signal-safe.h>
+#include <ust/lttng-ust-abi.h>
+#include <ust/tracepoint.h>
+#include <ust/tracepoint-internal.h>
+#include <ust/ust.h>
/*
- * communication thread mutex. Held when handling a command, also held
- * by fork() to deal with removal of threads, and by exit path.
+ * Has lttng ust comm constructor been called ?
+ */
+static int initialized;
+
+/*
+ * The ust_lock/ust_unlock lock is used as a communication thread mutex.
+ * Held when handling a command, also held by fork() to deal with
+ * removal of threads, and by exit path.
*/
-static pthread_mutex_t lttng_ust_comm_mutex = PTHREAD_MUTEX_INITIALIZER;
/* Should the ust comm thread quit ? */
static int lttng_ust_comm_should_quit;
+/*
+ * Wait for either of these before continuing to the main
+ * program:
+ * - the register_done message from sessiond daemon
+ * (will let the sessiond daemon enable sessions before main
+ * starts.)
+ * - sessiond daemon is not reachable.
+ * - timeout (ensuring applications are resilient to session
+ * daemon problems).
+ */
+static sem_t constructor_wait;
+/*
+ * Doing this for both the global and local sessiond.
+ */
+static int sem_count = { 2 };
+
/*
* Info about socket and associated listener thread.
*/
struct sock_info {
+ const char *name;
char sock_path[PATH_MAX];
int socket;
pthread_t ust_listener; /* listener thread */
int root_handle;
+ int constructor_sem_posted;
+ int allowed;
};
/* Socket from app (connect) to session daemon (listen) for communication */
struct sock_info global_apps = {
+ .name = "global",
.sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
.socket = -1,
.root_handle = -1,
+ .allowed = 1,
};
/* TODO: allow global_apps_sock_path override */
struct sock_info local_apps = {
+ .name = "local",
.socket = -1,
.root_handle = -1,
+ .allowed = 0, /* Check setuid bit first */
};
+extern void ltt_ring_buffer_client_overwrite_init(void);
+extern void ltt_ring_buffer_client_discard_init(void);
+extern void ltt_ring_buffer_metadata_client_init(void);
+extern void ltt_ring_buffer_client_overwrite_exit(void);
+extern void ltt_ring_buffer_client_discard_exit(void);
+extern void ltt_ring_buffer_metadata_client_exit(void);
+
static
-int setup_local_apps_socket(void)
+int setup_local_apps(void)
{
const char *home_dir;
+ /*
+ * Disallow per-user tracing for setuid binaries.
+ */
+ if (getuid() != geteuid()) {
+ local_apps.allowed = 0;
+ return 0;
+ } else {
+ local_apps.allowed = 1;
+ }
home_dir = (const char *) getenv("HOME");
if (!home_dir)
return -ENOENT;
int register_app_to_sessiond(int socket)
{
ssize_t ret;
+ int prctl_ret;
struct {
uint32_t major;
uint32_t minor;
pid_t pid;
+ pid_t ppid;
uid_t uid;
+ gid_t gid;
+ char name[16]; /* process name */
} reg_msg;
reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
reg_msg.pid = getpid();
+ reg_msg.ppid = getppid();
reg_msg.uid = getuid();
+ reg_msg.gid = getgid();
+ prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0);
+ if (prctl_ret) {
+ ERR("Error executing prctl");
+ return -errno;
+ }
ret = lttcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg));
if (ret >= 0 && ret != sizeof(reg_msg))
}
static
-int handle_message(int sock, struct lttcomm_ust_msg *lum)
+int handle_register_done(struct sock_info *sock_info)
+{
+ int ret;
+
+ if (sock_info->constructor_sem_posted)
+ return 0;
+ sock_info->constructor_sem_posted = 1;
+ ret = uatomic_add_return(&sem_count, -1);
+ if (ret == 0) {
+ ret = sem_post(&constructor_wait);
+ assert(!ret);
+ }
+ return 0;
+}
+
+static
+int handle_message(struct sock_info *sock_info,
+ int sock, struct lttcomm_ust_msg *lum)
{
int ret = 0;
const struct objd_ops *ops;
struct lttcomm_ust_reply lur;
- pthread_mutex_lock(<tng_ust_comm_mutex);
+ ust_lock();
memset(&lur, 0, sizeof(lur));
}
switch (lum->cmd) {
+ case LTTNG_UST_REGISTER_DONE:
+ if (lum->handle == LTTNG_UST_ROOT_HANDLE)
+ ret = handle_register_done(sock_info);
+ else
+ ret = -EINVAL;
+ break;
case LTTNG_UST_RELEASE:
if (lum->handle == LTTNG_UST_ROOT_HANDLE)
ret = -EPERM;
}
ret = send_reply(sock, &lur);
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ust_unlock();
return ret;
}
/* Restart trying to connect to the session daemon */
restart:
- pthread_mutex_lock(<tng_ust_comm_mutex);
+ ust_lock();
if (lttng_ust_comm_should_quit) {
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ust_unlock();
goto quit;
}
if (sock_info->socket != -1) {
ret = close(sock_info->socket);
if (ret) {
- ERR("Error closing local apps socket");
+ ERR("Error closing %s apps socket", sock_info->name);
}
sock_info->socket = -1;
}
/* Register */
ret = lttcomm_connect_unix_sock(sock_info->sock_path);
if (ret < 0) {
- ERR("Error connecting to global apps socket");
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ERR("Error connecting to %s apps socket", sock_info->name);
+ /*
+ * If we cannot find the sessiond daemon, don't delay
+ * constructor execution.
+ */
+ ret = handle_register_done(sock_info);
+ assert(!ret);
+ ust_unlock();
sleep(5);
goto restart;
}
ret = lttng_abi_create_root_handle();
if (ret) {
ERR("Error creating root handle");
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ust_unlock();
goto quit;
}
sock_info->root_handle = ret;
ret = register_app_to_sessiond(sock);
if (ret < 0) {
- ERR("Error registering app to local apps socket");
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ERR("Error registering to %s apps socket", sock_info->name);
+ /*
+ * If we cannot register to the sessiond daemon, don't
+ * delay constructor execution.
+ */
+ ret = handle_register_done(sock_info);
+ assert(!ret);
+ ust_unlock();
sleep(5);
goto restart;
}
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ust_unlock();
for (;;) {
ssize_t len;
len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
switch (len) {
case 0: /* orderly shutdown */
- DBG("ltt-sessiond has performed an orderly shutdown\n");
+ DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
goto end;
case sizeof(lum):
DBG("message received\n");
- ret = handle_message(sock, &lum);
+ ret = handle_message(sock_info, sock, &lum);
if (ret < 0) {
- ERR("Error handling message\n");
+ ERR("Error handling message for %s socket", sock_info->name);
}
continue;
case -1:
if (errno == ECONNRESET) {
- ERR("remote end closed connection\n");
+ ERR("%s remote end closed connection\n", sock_info->name);
goto end;
}
goto end;
default:
- ERR("incorrect message size: %zd\n", len);
+ ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
continue;
}
return NULL;
}
+/*
+ * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
+ */
+static
+int get_timeout(struct timespec *constructor_timeout)
+{
+ long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
+ char *str_delay;
+ int ret;
+
+ str_delay = getenv("UST_REGISTER_TIMEOUT");
+ if (str_delay) {
+ constructor_delay_ms = strtol(str_delay, NULL, 10);
+ }
+
+ switch (constructor_delay_ms) {
+ case -1:/* fall-through */
+ case 0:
+ return constructor_delay_ms;
+ default:
+ break;
+ }
+
+ /*
+ * If we are unable to find the current time, don't wait.
+ */
+ ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
+ if (ret) {
+ return -1;
+ }
+ constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
+ constructor_timeout->tv_nsec +=
+ (constructor_delay_ms % 1000UL) * 1000000UL;
+ if (constructor_timeout->tv_nsec >= 1000000000UL) {
+ constructor_timeout->tv_sec++;
+ constructor_timeout->tv_nsec -= 1000000000UL;
+ }
+ return 1;
+}
/*
* sessiond monitoring thread: monitor presence of global and per-user
*/
/* TODO */
-void __attribute__((constructor)) lttng_ust_comm_init(void)
+void __attribute__((constructor)) lttng_ust_init(void)
{
+ struct timespec constructor_timeout;
+ int timeout_mode;
int ret;
+ if (uatomic_xchg(&initialized, 1) == 1)
+ return;
+
+ /*
+ * We want precise control over the order in which we construct
+ * our sub-libraries vs starting to receive commands from
+ * sessiond (otherwise leading to errors when trying to create
+ * sessiond before the init functions are completed).
+ */
init_usterr();
+ init_tracepoint();
+ ltt_ring_buffer_metadata_client_init();
+ ltt_ring_buffer_client_overwrite_init();
+ ltt_ring_buffer_client_discard_init();
+
+ timeout_mode = get_timeout(&constructor_timeout);
+
+ ret = sem_init(&constructor_wait, 0, 0);
+ assert(!ret);
- ret = setup_local_apps_socket();
+ ret = setup_local_apps();
if (ret) {
- ERR("Error setting up to local apps socket");
+ ERR("Error setting up to local apps");
}
-#if 0
- ret = pthread_create(&global_apps.ust_listener, NULL,
- ust_listener_thread, &global_apps);
-#endif //0
ret = pthread_create(&local_apps.ust_listener, NULL,
ust_listener_thread, &local_apps);
+
+ if (local_apps.allowed) {
+ ret = pthread_create(&global_apps.ust_listener, NULL,
+ ust_listener_thread, &global_apps);
+ } else {
+ handle_register_done(&local_apps);
+ }
+
+ switch (timeout_mode) {
+ case 1: /* timeout wait */
+ do {
+ ret = sem_timedwait(&constructor_wait,
+ &constructor_timeout);
+ } while (ret < 0 && errno == EINTR);
+ if (ret < 0 && errno == ETIMEDOUT) {
+ ERR("Timed out waiting for ltt-sessiond");
+ } else {
+ assert(!ret);
+ }
+ break;
+ case -1:/* wait forever */
+ do {
+ ret = sem_wait(&constructor_wait);
+ } while (ret < 0 && errno == EINTR);
+ assert(!ret);
+ break;
+ case 0: /* no timeout */
+ break;
+ }
}
-void __attribute__((destructor)) lttng_ust_comm_exit(void)
+static
+void lttng_ust_cleanup(int exiting)
+{
+ cleanup_sock_info(&global_apps);
+ if (local_apps.allowed) {
+ cleanup_sock_info(&local_apps);
+ }
+ lttng_ust_abi_exit();
+ ltt_events_exit();
+ ltt_ring_buffer_client_discard_exit();
+ ltt_ring_buffer_client_overwrite_exit();
+ ltt_ring_buffer_metadata_client_exit();
+ exit_tracepoint();
+ if (!exiting) {
+ /* Reinitialize values for fork */
+ sem_count = 2;
+ lttng_ust_comm_should_quit = 0;
+ initialized = 0;
+ }
+}
+
+void __attribute__((destructor)) lttng_ust_exit(void)
{
int ret;
* mutexes to ensure it is not in a mutex critical section when
* pthread_cancel is later called.
*/
- pthread_mutex_lock(<tng_ust_comm_mutex);
+ ust_lock();
lttng_ust_comm_should_quit = 1;
- pthread_mutex_unlock(<tng_ust_comm_mutex);
+ ust_unlock();
-#if 0
ret = pthread_cancel(global_apps.ust_listener);
if (ret) {
ERR("Error cancelling global ust listener thread");
}
-#endif //0
+ if (local_apps.allowed) {
+ ret = pthread_cancel(local_apps.ust_listener);
+ if (ret) {
+ ERR("Error cancelling local ust listener thread");
+ }
+ }
+ lttng_ust_cleanup(1);
+}
- cleanup_sock_info(&global_apps);
+/*
+ * We exclude the worker threads across fork and clone (except
+ * CLONE_VM), because these system calls only keep the forking thread
+ * running in the child. Therefore, we don't want to call fork or clone
+ * in the middle of an tracepoint or ust tracing state modification.
+ * Holding this mutex protects these structures across fork and clone.
+ */
+void ust_before_fork(ust_fork_info_t *fork_info)
+{
+ /*
+ * Disable signals. This is to avoid that the child intervenes
+ * before it is properly setup for tracing. It is safer to
+ * disable all signals, because then we know we are not breaking
+ * anything by restoring the original mask.
+ */
+ sigset_t all_sigs;
+ int ret;
- ret = pthread_cancel(local_apps.ust_listener);
- if (ret) {
- ERR("Error cancelling local ust listener thread");
+ /* Disable signals */
+ sigfillset(&all_sigs);
+ ret = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
+ if (ret == -1) {
+ PERROR("sigprocmask");
}
+ ust_lock();
+ rcu_bp_before_fork();
+}
- cleanup_sock_info(&local_apps);
+static void ust_after_fork_common(ust_fork_info_t *fork_info)
+{
+ int ret;
- lttng_ust_abi_exit();
- ltt_events_exit();
+ DBG("process %d", getpid());
+ ust_unlock();
+ /* Restore signals */
+ ret = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
+ if (ret == -1) {
+ PERROR("sigprocmask");
+ }
+}
+
+void ust_after_fork_parent(ust_fork_info_t *fork_info)
+{
+ DBG("process %d", getpid());
+ rcu_bp_after_fork_parent();
+ /* Release mutexes and reenable signals */
+ ust_after_fork_common(fork_info);
+}
+
+/*
+ * After fork, in the child, we need to cleanup all the leftover state,
+ * except the worker thread which already magically disappeared thanks
+ * to the weird Linux fork semantics. After tyding up, we call
+ * lttng_ust_init() again to start over as a new PID.
+ *
+ * This is meant for forks() that have tracing in the child between the
+ * fork and following exec call (if there is any).
+ */
+void ust_after_fork_child(ust_fork_info_t *fork_info)
+{
+ DBG("process %d", getpid());
+ /* Release urcu mutexes */
+ rcu_bp_after_fork_child();
+ lttng_ust_cleanup(0);
+ lttng_ust_init();
+ /* Release mutexes and reenable signals */
+ ust_after_fork_common(fork_info);
}
projects / lttng-ust.git / blobdiff