[ltt-control.git] / lttng / lttngtrace.c

/*
 * lttngtrace.c
 *
 * lttngtrace starts/stop system wide tracing around program execution.
 *
 * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This file should be setuid root, and belong to a "tracing" group. Only users
 * part of the tracing group can trace and view the traces gathered.
 *
 * TODO: LTTng should support per-session tracepoint activation.
 * TODO: use mkstemp() and save last trace name in user's home directory.
 * TODO: drop priv + reenable standard signal handlers + call lttv at the end.
 * TODO: -o option should be limited to creation of files in locations that the
 *       calling user has file creation access.
 */

#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <dirent.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/types.h>

#if DEBUG
#define printf_dbg(fmt, args...)	printf(fmt, args)
#else
#define printf_dbg(fmt, ...)
#endif

static char *trace_path;
static char trace_path_pid[PATH_MAX];
static int autotrace;	/*
			 * Is the trace_path automatically chosen in /tmp ? Can
			 * we unlink if needed ?
			 */
static int sigfwd_pid;
static char *progname = NULL;

void usage(void) {
	fprintf(stderr, "usage : %s [-o trace_name] command\n", progname);
	fprintf(stderr, "\nTracing tool for LTTng and UST\n\
\n\
Options:\n\
	-o trace_name\t\tOutput file of the trace\n\
");
}

static int recunlink(const char *dirname)
{
	DIR *dir;
	struct dirent *entry;
	char path[PATH_MAX];

	dir = opendir(dirname);
	if (dir == NULL) {
		if (errno == ENOENT)
			return 0;
		perror("Error opendir()");
		return -errno;
	}

	while ((entry = readdir(dir)) != NULL) {
		if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) {
			snprintf(path, (size_t) PATH_MAX, "%s/%s", dirname,
				 entry->d_name);
			if (entry->d_type == DT_DIR)
				recunlink(path);
			else
				unlink(path);
		}
	}
	closedir(dir);
	rmdir(dirname);

	return 0;
}

static int start_tracing(void)
{
	int ret;
	char command[PATH_MAX];

	if (autotrace) {
		ret = recunlink(trace_path);
		if (ret)
			return ret;
	}

	/*
	 * Create the directory in /tmp to deal with races (refuse if fail).
	 * Only allow user and group to read the trace data (to limit
	 * information disclosure).
	 */
	ret = mkdir(trace_path, S_IRWXU|S_IRWXG);
	if (ret) {
		perror("Trace directory creation error");
		return ret;
	}
	ret = system("ltt-armall > /dev/null");
	if (ret)
		return ret;

	ret = snprintf(command, PATH_MAX - 1,
		       "lttctl -C -w %s autotrace1 > /dev/null",
		       trace_path);
	ret = ret < 0 ? ret : 0;
	if (ret)
		return ret;
	ret = system(command);
	if (ret)
		return ret;
}

static int stop_tracing(uid_t uid, gid_t egid)
{
	int ret;

	ret = system("lttctl -D autotrace1 > /dev/null");
	if (ret)
		return ret;
	ret = system("ltt-disarmall > /dev/null");
	if (ret)
		return ret;
	/* Hand the trace back to the user after tracing is over */
	ret = chown(trace_path, uid, egid);
	if (ret) {
		perror("chown error");
		return ret;
	}
}

static int write_child_pid(pid_t pid, uid_t uid, gid_t gid)
{
	int fd;
	FILE *fp;
	int ret;

	/* Create the file as exclusive to deal with /tmp file creation races */
	fd = open(trace_path_pid, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC,
		  S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
	fp = fdopen(fd, "w");
	if (!fp) {
		perror("Error writing child pid");
		return -errno;
	}

	fprintf(fp, "%u", (unsigned int) pid);
	ret = fclose(fp);
	if (ret)
		perror("Error in fclose");
	/* Hand pid information file back to user */
	ret = chown(trace_path_pid, uid, gid);
	if (ret)
		perror("chown error");
	return ret;
}

static int parse_options(int argc, char **argv, int *arg)
{
	int i, c;

	while ((c = getopt(argc, argv, "ho:")) != -1) {
		switch (c) {
			case 'o':
				trace_path = strdup(optarg);
				break;
			case 'h':
				usage();
				exit(EXIT_SUCCESS);
			case '?':
				usage();
				exit(EXIT_FAILURE);
			default:
				exit(EXIT_FAILURE);
		}
	}

	if (argc - optind > 0) {
		for (i = optind + 1; i < argc; i++) {
			printf ("Non-option argument %s\n", argv[i]);
		}
	} else {
		usage();
		exit(EXIT_FAILURE);
	}

	*arg = optind;

	return 0;
}

static int init_trace_path(void)
{
	int ret;

	if (!trace_path) {
		trace_path = "/tmp/autotrace1";
		autotrace = 1;
	}
	ret = snprintf(trace_path_pid, PATH_MAX - 1, "%s/%s",
		       trace_path, "pid");
	ret = ret < 0 ? ret : 0;
	return ret;
}

static void sighandler(int signo, siginfo_t *siginfo, void *context)
{
	kill(sigfwd_pid, signo);
}

static int init_sighand(sigset_t *saved_mask)
{
	sigset_t sig_all_mask;
	int gret = 0, ret;

	/* Block signals */
	ret = sigfillset(&sig_all_mask);
	if (ret)
		perror("Error in sigfillset");
	gret = (gret == 0) ? ret : gret;
	ret = sigprocmask(SIG_SETMASK, &sig_all_mask, saved_mask);
	if (ret)
		perror("Error in sigprocmask");
	gret = (gret == 0) ? ret : gret;
	return gret;
}

static int forward_signals(pid_t pid, sigset_t *saved_mask)
{
	struct sigaction act;
	int gret = 0, ret;

	/* Forward SIGINT and SIGTERM */
	sigfwd_pid = pid;
	act.sa_sigaction = sighandler;
	act.sa_flags = SA_SIGINFO | SA_RESTART;
	sigemptyset(&act.sa_mask);
	ret = sigaction(SIGINT, &act, NULL);
	if (ret)
		perror("Error in sigaction");
	gret = (gret == 0) ? ret : gret;
	ret = sigaction(SIGTERM, &act, NULL);
	if (ret)
		perror("Error in sigaction");
	gret = (gret == 0) ? ret : gret;

	/* Reenable signals */
	ret = sigprocmask(SIG_SETMASK, saved_mask, NULL);
	if (ret)
		perror("Error in sigprocmask");
	gret = (gret == 0) ? ret : gret;
	return gret;
}

int main(int argc, char *argv[])
{
	uid_t euid, uid;
	gid_t egid, gid;
	pid_t pid;
	int gret = 0, ret = 0;
	int arg = 1;
	sigset_t saved_mask;

	progname = argv[0];

	if (argc < 2) {
		usage();
		return -ENOENT;
	}

	euid = geteuid();
	uid = getuid();
	egid = getegid();
	gid = geteuid();

	if (euid != 0 && uid != 0) {
		printf("%s must be setuid root\n", progname);
		return -EPERM;
	}

	printf_dbg("euid: %d\n", euid);
	printf_dbg("uid: %d\n", uid);
	printf_dbg("egid: %d\n", egid);
	printf_dbg("gid: %d\n", gid);

	ret = parse_options(argc, argv, &arg);
	if (ret)
		return ret;

	ret = init_trace_path();
	gret = (gret == 0) ? ret : gret;

	ret = init_sighand(&saved_mask);
	gret = (gret == 0) ? ret : gret;

	ret = start_tracing();
	if (ret)
		return ret;

	pid = fork();
	if (pid > 0) {		/* parent */
		int status;

		ret = forward_signals(pid, &saved_mask);
		gret = (gret == 0) ? ret : gret;
		pid = wait(&status);
		if (pid == -1)
			gret = (gret == 0) ? -errno : gret;

		ret = stop_tracing(uid, egid);
		gret = (gret == 0) ? ret : gret;
		ret = write_child_pid(pid, uid, egid);
		gret = (gret == 0) ? ret : gret;
	} else if (pid == 0) {	/* child */
		/* Drop root euid before executing child program */
		seteuid(uid);
		/* Reenable signals */
		ret = sigprocmask(SIG_SETMASK, &saved_mask, NULL);
		if (ret) {
			perror("Error in sigprocmask");
			return ret;
		}
		ret = execvp(argv[arg], &argv[arg]);
		if (ret)
			perror("Execution error");
		return ret;
	} else {		/* error */
		perror("Error in fork");
		return -errno;
	}
	return ret;
}
Commit	Line	Data
6f3a6fc5 MD	1	/*
	2	* lttngtrace.c
	3	*
	4	* lttngtrace starts/stop system wide tracing around program execution.
	5	*
	6	* Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License along
	19	* with this program; if not, write to the Free Software Foundation, Inc.,
	20	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	21	*
	22	* This file should be setuid root, and belong to a "tracing" group. Only users
	23	* part of the tracing group can trace and view the traces gathered.
	24	*
	25	* TODO: LTTng should support per-session tracepoint activation.
	26	* TODO: use mkstemp() and save last trace name in user's home directory.
c94203ed	27	* TODO: drop priv + reenable standard signal handlers + call lttv at the end.
432a1b04 MD	28	* TODO: -o option should be limited to creation of files in locations that the
432a1b04 MD	29	* calling user has file creation access.
6f3a6fc5 MD	30	*/
	31
	32	#include <errno.h>
	33	#include <stdio.h>
	34	#include <fcntl.h>
	35	#include <signal.h>
	36	#include <unistd.h>
	37	#include <stdlib.h>
	38	#include <string.h>
	39	#include <limits.h>
	40	#include <dirent.h>
	41	#include <sys/wait.h>
	42	#include <sys/stat.h>
	43	#include <sys/types.h>
	44
	45	#if DEBUG
	46	#define printf_dbg(fmt, args...) printf(fmt, args)
	47	#else
	48	#define printf_dbg(fmt, ...)
	49	#endif
	50
	51	static char *trace_path;
	52	static char trace_path_pid[PATH_MAX];
	53	static int autotrace; /*
	54	* Is the trace_path automatically chosen in /tmp ? Can
	55	* we unlink if needed ?
	56	*/
	57	static int sigfwd_pid;
8f48e913 MD	58	static char *progname = NULL;
	59
	60	void usage(void) {
	61	fprintf(stderr, "usage : %s [-o trace_name] command\n", progname);
	62	fprintf(stderr, "\nTracing tool for LTTng and UST\n\
	63	\n\
	64	Options:\n\
	65	-o trace_name\t\tOutput file of the trace\n\
	66	");
	67	}
6f3a6fc5 MD	68
	69	static int recunlink(const char *dirname)
	70	{
	71	DIR *dir;
	72	struct dirent *entry;
	73	char path[PATH_MAX];
	74
	75	dir = opendir(dirname);
	76	if (dir == NULL) {
	77	if (errno == ENOENT)
	78	return 0;
	79	perror("Error opendir()");
	80	return -errno;
	81	}
	82
	83	while ((entry = readdir(dir)) != NULL) {
	84	if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) {
	85	snprintf(path, (size_t) PATH_MAX, "%s/%s", dirname,
	86	entry->d_name);
	87	if (entry->d_type == DT_DIR)
	88	recunlink(path);
	89	else
	90	unlink(path);
	91	}
	92	}
	93	closedir(dir);
	94	rmdir(dirname);
	95
	96	return 0;
	97	}
	98
	99	static int start_tracing(void)
	100	{
	101	int ret;
	102	char command[PATH_MAX];
	103
	104	if (autotrace) {
	105	ret = recunlink(trace_path);
	106	if (ret)
	107	return ret;
	108	}
	109
	110	/*
	111	* Create the directory in /tmp to deal with races (refuse if fail).
	112	* Only allow user and group to read the trace data (to limit
	113	* information disclosure).
	114	*/
	115	ret = mkdir(trace_path, S_IRWXU\|S_IRWXG);
	116	if (ret) {
	117	perror("Trace directory creation error");
	118	return ret;
	119	}
	120	ret = system("ltt-armall > /dev/null");
	121	if (ret)
	122	return ret;
	123
	124	ret = snprintf(command, PATH_MAX - 1,
	125	"lttctl -C -w %s autotrace1 > /dev/null",
	126	trace_path);
	127	ret = ret < 0 ? ret : 0;
	128	if (ret)
	129	return ret;
	130	ret = system(command);
	131	if (ret)
132	return ret;
133	}
134
135	static int stop_tracing(uid_t uid, gid_t egid)
136	{
137	int ret;
138
139	ret = system("lttctl -D autotrace1 > /dev/null");
140	if (ret)
141	return ret;
142	ret = system("ltt-disarmall > /dev/null");
143	if (ret)
144	return ret;
145	/* Hand the trace back to the user after tracing is over */
146	ret = chown(trace_path, uid, egid);
147	if (ret) {
148	perror("chown error");
149	return ret;
150	}
151	}
152
153	static int write_child_pid(pid_t pid, uid_t uid, gid_t gid)
154	{
155	int fd;
156	FILE *fp;
157	int ret;
158
159	/* Create the file as exclusive to deal with /tmp file creation races */
160	fd = open(trace_path_pid, O_WRONLY \| O_CREAT \| O_EXCL \| O_TRUNC,
161	S_IRUSR \| S_IWUSR \| S_IRGRP \| S_IWGRP);
162	fp = fdopen(fd, "w");
163	if (!fp) {
164	perror("Error writing child pid");
165	return -errno;
166	}
8f48e913	167
6f3a6fc5 MD	168	fprintf(fp, "%u", (unsigned int) pid);
	169	ret = fclose(fp);
	170	if (ret)
	171	perror("Error in fclose");
	172	/* Hand pid information file back to user */
	173	ret = chown(trace_path_pid, uid, gid);
	174	if (ret)
	175	perror("chown error");
	176	return ret;
	177	}
	178
8f48e913	179	static int parse_options(int argc, char *argv, int arg)
6f3a6fc5	180	{
8f48e913 MD	181	int i, c;
	182
	183	while ((c = getopt(argc, argv, "ho:")) != -1) {
	184	switch (c) {
	185	case 'o':
	186	trace_path = strdup(optarg);
6f3a6fc5	187	break;
8f48e913 MD	188	case 'h':
	189	usage();
	190	exit(EXIT_SUCCESS);
	191	case '?':
	192	usage();
	193	exit(EXIT_FAILURE);
	194	default:
	195	exit(EXIT_FAILURE);
6f3a6fc5 MD	196	}
6f3a6fc5 MD	197	}
8f48e913 MD	198
	199	if (argc - optind > 0) {
	200	for (i = optind + 1; i < argc; i++) {
	201	printf ("Non-option argument %s\n", argv[i]);
	202	}
	203	} else {
	204	usage();
	205	exit(EXIT_FAILURE);
	206	}
	207
	208	*arg = optind;
	209
	210	return 0;
6f3a6fc5 MD	211	}
	212
	213	static int init_trace_path(void)
	214	{
	215	int ret;
	216
	217	if (!trace_path) {
	218	trace_path = "/tmp/autotrace1";
	219	autotrace = 1;
	220	}
	221	ret = snprintf(trace_path_pid, PATH_MAX - 1, "%s/%s",
	222	trace_path, "pid");
	223	ret = ret < 0 ? ret : 0;
	224	return ret;
	225	}
	226
	227	static void sighandler(int signo, siginfo_t siginfo, void context)
	228	{
	229	kill(sigfwd_pid, signo);
	230	}
	231
	232	static int init_sighand(sigset_t *saved_mask)
	233	{
	234	sigset_t sig_all_mask;
	235	int gret = 0, ret;
	236
	237	/* Block signals */
	238	ret = sigfillset(&sig_all_mask);
	239	if (ret)
	240	perror("Error in sigfillset");
	241	gret = (gret == 0) ? ret : gret;
	242	ret = sigprocmask(SIG_SETMASK, &sig_all_mask, saved_mask);
	243	if (ret)
	244	perror("Error in sigprocmask");
	245	gret = (gret == 0) ? ret : gret;
	246	return gret;
	247	}
	248
	249	static int forward_signals(pid_t pid, sigset_t *saved_mask)
	250	{
	251	struct sigaction act;
	252	int gret = 0, ret;
	253
	254	/* Forward SIGINT and SIGTERM */
	255	sigfwd_pid = pid;
	256	act.sa_sigaction = sighandler;
	257	act.sa_flags = SA_SIGINFO \| SA_RESTART;
	258	sigemptyset(&act.sa_mask);
	259	ret = sigaction(SIGINT, &act, NULL);
	260	if (ret)
	261	perror("Error in sigaction");
	262	gret = (gret == 0) ? ret : gret;
	263	ret = sigaction(SIGTERM, &act, NULL);
	264	if (ret)
	265	perror("Error in sigaction");
	266	gret = (gret == 0) ? ret : gret;
	267
	268	/* Reenable signals */
	269	ret = sigprocmask(SIG_SETMASK, saved_mask, NULL);
	270	if (ret)
	271	perror("Error in sigprocmask");
	272	gret = (gret == 0) ? ret : gret;
	273	return gret;
	274	}
275
276	int main(int argc, char *argv[])
277	{
278	uid_t euid, uid;
279	gid_t egid, gid;
280	pid_t pid;
281	int gret = 0, ret = 0;
282	int arg = 1;
283	sigset_t saved_mask;
284
8f48e913 MD	285	progname = argv[0];
	286
	287	if (argc < 2) {
	288	usage();
6f3a6fc5	289	return -ENOENT;
8f48e913	290	}
6f3a6fc5 MD	291
	292	euid = geteuid();
	293	uid = getuid();
	294	egid = getegid();
	295	gid = geteuid();
	296
	297	if (euid != 0 && uid != 0) {
8f48e913	298	printf("%s must be setuid root\n", progname);
6f3a6fc5 MD	299	return -EPERM;
	300	}
	301
	302	printf_dbg("euid: %d\n", euid);
	303	printf_dbg("uid: %d\n", uid);
	304	printf_dbg("egid: %d\n", egid);
	305	printf_dbg("gid: %d\n", gid);
	306
8f48e913 MD	307	ret = parse_options(argc, argv, &arg);
	308	if (ret)
	309	return ret;
6f3a6fc5 MD	310
	311	ret = init_trace_path();
	312	gret = (gret == 0) ? ret : gret;
	313
	314	ret = init_sighand(&saved_mask);
	315	gret = (gret == 0) ? ret : gret;
	316
	317	ret = start_tracing();
	318	if (ret)
	319	return ret;
	320
	321	pid = fork();
	322	if (pid > 0) { /* parent */
	323	int status;
	324
	325	ret = forward_signals(pid, &saved_mask);
	326	gret = (gret == 0) ? ret : gret;
	327	pid = wait(&status);
	328	if (pid == -1)
	329	gret = (gret == 0) ? -errno : gret;
	330
	331	ret = stop_tracing(uid, egid);
	332	gret = (gret == 0) ? ret : gret;
	333	ret = write_child_pid(pid, uid, egid);
	334	gret = (gret == 0) ? ret : gret;
	335	} else if (pid == 0) { /* child */
	336	/* Drop root euid before executing child program */
	337	seteuid(uid);
	338	/* Reenable signals */
	339	ret = sigprocmask(SIG_SETMASK, &saved_mask, NULL);
	340	if (ret) {
	341	perror("Error in sigprocmask");
	342	return ret;
	343	}
	344	ret = execvp(argv[arg], &argv[arg]);
	345	if (ret)
	346	perror("Execution error");
	347	return ret;
	348	} else { /* error */
	349	perror("Error in fork");
	350	return -errno;
	351	}
	352	return ret;
	353	}