From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Wed, 16 May 2018 22:24:01 +0000 (-0400)
Subject: relayd: introduce --working-directory/-w options
X-Git-Tag: v2.12.0-rc1~295
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=ce9ee1fb2847b1603c4382c82aef95121f0e3d07

relayd: introduce --working-directory/-w options

This new option allows the user to specify the working directory (CWD) of the
lttng-relayd process. This is especially useful when lttng-relayd is
started in daemon mode (-d) because by default the CWD is set to "/".
This can help control where coredumps, if any, get generated.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 2836c489c..ad97a0b9b 100644
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -96,7 +96,7 @@ enum relay_connection_status {
 };
 
 /* command line options */
-char *opt_output_path;
+char *opt_output_path, *opt_working_directory;
 static int opt_daemon, opt_background, opt_print_version;
 
 /*
@@ -184,6 +184,7 @@ static struct option long_options[] = {
 	{ "verbose", 0, 0, 'v', },
 	{ "config", 1, 0, 'f' },
 	{ "version", 0, 0, 'V' },
+	{ "working-directory", 1, 0, 'w', },
 	{ NULL, 0, 0, 0, },
 };
 
@@ -311,6 +312,20 @@ static int set_option(int opt, const char *arg, const char *optname)
 			}
 		}
 		break;
+	case 'w':
+		if (lttng_is_setuid_setgid()) {
+			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
+				"-w, --working-directory");
+		} else {
+			ret = asprintf(&opt_working_directory, "%s", arg);
+			if (ret < 0) {
+				ret = -errno;
+				PERROR("asprintf opt_working_directory");
+				goto end;
+			}
+		}
+		break;
+
 	case 'v':
 		/* Verbose level can increase using multiple -v */
 		if (arg) {
@@ -541,8 +556,8 @@ static void relayd_cleanup(void)
 	if (sessions_ht)
 		lttng_ht_destroy(sessions_ht);
 
-	/* free the dynamically allocated opt_output_path */
 	free(opt_output_path);
+	free(opt_working_directory);
 
 	/* Close thread quit pipes */
 	utils_close_pipe(thread_quit_pipe);
@@ -3729,6 +3744,14 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (opt_working_directory) {
+		ret = utils_change_working_directory(opt_working_directory);
+		if (ret) {
+			/* All errors are already logged. */
+			goto exit_options;
+		}
+	}
+
 	sessiond_trace_chunk_registry = sessiond_trace_chunk_registry_create();
 	if (!sessiond_trace_chunk_registry) {
 		ERR("Failed to initialize session daemon trace chunk registry");
diff --git a/src/common/utils.c b/src/common/utils.c
index 3cdb6b760..0147c8c99 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -1501,3 +1501,35 @@ int utils_get_memory_total(size_t *value)
 {
 	return read_proc_meminfo_field(PROC_MEMINFO_MEMTOTAL_LINE, value);
 }
+
+LTTNG_HIDDEN
+int utils_change_working_directory(const char *path)
+{
+	int ret;
+
+	assert(path);
+
+	DBG("Changing working directory to \"%s\"", path);
+	ret = chdir(path);
+	if (ret) {
+		PERROR("Failed to change working directory to \"%s\"", path);
+		goto end;
+	}
+
+	/* Check for write access */
+	if (access(path, W_OK)) {
+		if (errno == EACCES) {
+			/*
+			 * Do not treat this as an error since the permission
+			 * might change in the lifetime of the process
+			 */
+			DBG("Working directory \"%s\" is not writable", path);
+		} else {
+			PERROR("Failed to check if working directory \"%s\" is writable",
+					path);
+		}
+	}
+
+end:
+	return ret;
+}
diff --git a/src/common/utils.h b/src/common/utils.h
index 11388c903..27a6f4849 100644
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -63,5 +63,6 @@ int utils_truncate_stream_file(int fd, off_t length);
 int utils_show_help(int section, const char *page_name, const char *help_msg);
 int utils_get_memory_available(size_t *value);
 int utils_get_memory_total(size_t *value);
+int utils_change_working_directory(const char *path);
 
 #endif /* _COMMON_UTILS_H */