X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=libust%2Flttng-ust-comm.c;h=58e9a6487707ab5097dfcbe8eb563cd5463186f4;hb=b751f722f7324ab5ea4955b0150c98512a364f85;hp=ebc94192aa406eff01f62a8e20a475bc1840e311;hpb=48279e22a39cde0cf97b9ed0077e850309112637;p=lttng-ust.git

diff --git a/libust/lttng-ust-comm.c b/libust/lttng-ust-comm.c
index ebc94192..58e9a648 100644
--- a/libust/lttng-ust-comm.c
+++ b/libust/lttng-ust-comm.c
@@ -21,18 +21,23 @@
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/prctl.h>
 #include <unistd.h>
 #include <errno.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>
+#include "ltt-tracer-core.h"
 
 /*
  * Has lttng ust comm constructor been called ?
@@ -40,10 +45,10 @@
 static int initialized;
 
 /*
- * communication thread mutex. Held when handling a command, also held
- * by fork() to deal with removal of threads, and by exit path.
+ * 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;
@@ -73,7 +78,8 @@ struct sock_info {
 	int socket;
 	pthread_t ust_listener;	/* listener thread */
 	int root_handle;
-	int constructor_sem_posted;;
+	int constructor_sem_posted;
+	int allowed;
 };
 
 /* Socket from app (connect) to session daemon (listen) for communication */
@@ -82,6 +88,7 @@ struct sock_info global_apps = {
 	.sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
 	.socket = -1,
 	.root_handle = -1,
+	.allowed = 1,
 };
 
 /* TODO: allow global_apps_sock_path override */
@@ -90,6 +97,7 @@ 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);
@@ -100,10 +108,19 @@ 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;
@@ -116,17 +133,28 @@ static
 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, &reg_msg, sizeof(reg_msg));
 	if (ret >= 0 && ret != sizeof(reg_msg))
@@ -180,7 +208,7 @@ int handle_message(struct sock_info *sock_info,
 	const struct objd_ops *ops;
 	struct lttcomm_ust_reply lur;
 
-	pthread_mutex_lock(&lttng_ust_comm_mutex);
+	ust_lock();
 
 	memset(&lur, 0, sizeof(lur));
 
@@ -228,7 +256,7 @@ end:
 	}
 	ret = send_reply(sock, &lur);
 
-	pthread_mutex_unlock(&lttng_ust_comm_mutex);
+	ust_unlock();
 	return ret;
 }
 
@@ -268,10 +296,10 @@ void *ust_listener_thread(void *arg)
 
 	/* Restart trying to connect to the session daemon */
 restart:
-	pthread_mutex_lock(&lttng_ust_comm_mutex);
+	ust_lock();
 
 	if (lttng_ust_comm_should_quit) {
-		pthread_mutex_unlock(&lttng_ust_comm_mutex);
+		ust_unlock();
 		goto quit;
 	}
 
@@ -295,7 +323,7 @@ restart:
 		 */
 		ret = handle_register_done(sock_info);
 		assert(!ret);
-		pthread_mutex_unlock(&lttng_ust_comm_mutex);
+		ust_unlock();
 		sleep(5);
 		goto restart;
 	}
@@ -310,7 +338,7 @@ restart:
 		ret = lttng_abi_create_root_handle();
 		if (ret) {
 			ERR("Error creating root handle");
-			pthread_mutex_unlock(&lttng_ust_comm_mutex);
+			ust_unlock();
 			goto quit;
 		}
 		sock_info->root_handle = ret;
@@ -325,11 +353,11 @@ restart:
 		 */
 		ret = handle_register_done(sock_info);
 		assert(!ret);
-		pthread_mutex_unlock(&lttng_ust_comm_mutex);
+		ust_unlock();
 		sleep(5);
 		goto restart;
 	}
-	pthread_mutex_unlock(&lttng_ust_comm_mutex);
+	ust_unlock();
 
 	for (;;) {
 		ssize_t len;
@@ -437,16 +465,20 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	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");
 	}
-
-	ret = pthread_create(&global_apps.ust_listener, NULL,
-			ust_listener_thread, &global_apps);
 	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 {
@@ -470,6 +502,27 @@ void __attribute__((constructor)) lttng_ust_init(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;
@@ -485,30 +538,88 @@ void __attribute__((destructor)) lttng_ust_exit(void)
 	 * mutexes to ensure it is not in a mutex critical section when
 	 * pthread_cancel is later called.
 	 */
-	pthread_mutex_lock(&lttng_ust_comm_mutex);
+	ust_lock();
 	lttng_ust_comm_should_quit = 1;
-	pthread_mutex_unlock(&lttng_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();
-	ltt_ring_buffer_client_discard_exit();
-	ltt_ring_buffer_client_overwrite_exit();
-	ltt_ring_buffer_metadata_client_exit();
-	exit_tracepoint();
+	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);
 }