[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.
 */

#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.
6f3a6fc5 MD	28	*/
	29
	30	#include <errno.h>
	31	#include <stdio.h>
	32	#include <fcntl.h>
	33	#include <signal.h>
	34	#include <unistd.h>
	35	#include <stdlib.h>
	36	#include <string.h>
	37	#include <limits.h>
	38	#include <dirent.h>
	39	#include <sys/wait.h>
	40	#include <sys/stat.h>
	41	#include <sys/types.h>
	42
	43	#if DEBUG
	44	#define printf_dbg(fmt, args...) printf(fmt, args)
	45	#else
	46	#define printf_dbg(fmt, ...)
	47	#endif
	48
	49	static char *trace_path;
	50	static char trace_path_pid[PATH_MAX];
	51	static int autotrace; /*
	52	* Is the trace_path automatically chosen in /tmp ? Can
	53	* we unlink if needed ?
	54	*/
	55	static int sigfwd_pid;
8f48e913 MD	56	static char *progname = NULL;
	57
	58	void usage(void) {
	59	fprintf(stderr, "usage : %s [-o trace_name] command\n", progname);
	60	fprintf(stderr, "\nTracing tool for LTTng and UST\n\
	61	\n\
	62	Options:\n\
	63	-o trace_name\t\tOutput file of the trace\n\
	64	");
	65	}
6f3a6fc5 MD	66
	67	static int recunlink(const char *dirname)
	68	{
	69	DIR *dir;
	70	struct dirent *entry;
	71	char path[PATH_MAX];
	72
	73	dir = opendir(dirname);
	74	if (dir == NULL) {
	75	if (errno == ENOENT)
	76	return 0;
	77	perror("Error opendir()");
	78	return -errno;
	79	}
	80
	81	while ((entry = readdir(dir)) != NULL) {
	82	if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) {
	83	snprintf(path, (size_t) PATH_MAX, "%s/%s", dirname,
	84	entry->d_name);
	85	if (entry->d_type == DT_DIR)
	86	recunlink(path);
	87	else
	88	unlink(path);
	89	}
	90	}
	91	closedir(dir);
	92	rmdir(dirname);
	93
	94	return 0;
	95	}
	96
	97	static int start_tracing(void)
	98	{
	99	int ret;
	100	char command[PATH_MAX];
	101
	102	if (autotrace) {
	103	ret = recunlink(trace_path);
	104	if (ret)
	105	return ret;
	106	}
	107
	108	/*
	109	* Create the directory in /tmp to deal with races (refuse if fail).
	110	* Only allow user and group to read the trace data (to limit
	111	* information disclosure).
	112	*/
	113	ret = mkdir(trace_path, S_IRWXU\|S_IRWXG);
	114	if (ret) {
	115	perror("Trace directory creation error");
	116	return ret;
	117	}
	118	ret = system("ltt-armall > /dev/null");
	119	if (ret)
	120	return ret;
	121
	122	ret = snprintf(command, PATH_MAX - 1,
	123	"lttctl -C -w %s autotrace1 > /dev/null",
	124	trace_path);
	125	ret = ret < 0 ? ret : 0;
	126	if (ret)
	127	return ret;
	128	ret = system(command);
	129	if (ret)
130	return ret;
131	}
132
133	static int stop_tracing(uid_t uid, gid_t egid)
134	{
135	int ret;
136
137	ret = system("lttctl -D autotrace1 > /dev/null");
138	if (ret)
139	return ret;
140	ret = system("ltt-disarmall > /dev/null");
141	if (ret)
142	return ret;
143	/* Hand the trace back to the user after tracing is over */
144	ret = chown(trace_path, uid, egid);
145	if (ret) {
146	perror("chown error");
147	return ret;
148	}
149	}
150
151	static int write_child_pid(pid_t pid, uid_t uid, gid_t gid)
152	{
153	int fd;
154	FILE *fp;
155	int ret;
156
157	/* Create the file as exclusive to deal with /tmp file creation races */
158	fd = open(trace_path_pid, O_WRONLY \| O_CREAT \| O_EXCL \| O_TRUNC,
159	S_IRUSR \| S_IWUSR \| S_IRGRP \| S_IWGRP);
160	fp = fdopen(fd, "w");
161	if (!fp) {
162	perror("Error writing child pid");
163	return -errno;
164	}
8f48e913	165
6f3a6fc5 MD	166	fprintf(fp, "%u", (unsigned int) pid);
	167	ret = fclose(fp);
	168	if (ret)
	169	perror("Error in fclose");
	170	/* Hand pid information file back to user */
	171	ret = chown(trace_path_pid, uid, gid);
	172	if (ret)
	173	perror("chown error");
	174	return ret;
	175	}
	176
8f48e913	177	static int parse_options(int argc, char *argv, int arg)
6f3a6fc5	178	{
8f48e913 MD	179	int i, c;
	180
	181	while ((c = getopt(argc, argv, "ho:")) != -1) {
	182	switch (c) {
	183	case 'o':
	184	trace_path = strdup(optarg);
6f3a6fc5	185	break;
8f48e913 MD	186	case 'h':
	187	usage();
	188	exit(EXIT_SUCCESS);
	189	case '?':
	190	usage();
	191	exit(EXIT_FAILURE);
	192	default:
	193	exit(EXIT_FAILURE);
6f3a6fc5 MD	194	}
6f3a6fc5 MD	195	}
8f48e913 MD	196
	197	if (argc - optind > 0) {
	198	for (i = optind + 1; i < argc; i++) {
	199	printf ("Non-option argument %s\n", argv[i]);
	200	}
	201	} else {
	202	usage();
	203	exit(EXIT_FAILURE);
	204	}
	205
	206	*arg = optind;
	207
	208	return 0;
6f3a6fc5 MD	209	}
	210
	211	static int init_trace_path(void)
	212	{
	213	int ret;
	214
	215	if (!trace_path) {
	216	trace_path = "/tmp/autotrace1";
	217	autotrace = 1;
	218	}
	219	ret = snprintf(trace_path_pid, PATH_MAX - 1, "%s/%s",
	220	trace_path, "pid");
	221	ret = ret < 0 ? ret : 0;
	222	return ret;
	223	}
	224
	225	static void sighandler(int signo, siginfo_t siginfo, void context)
	226	{
	227	kill(sigfwd_pid, signo);
	228	}
	229
	230	static int init_sighand(sigset_t *saved_mask)
	231	{
	232	sigset_t sig_all_mask;
	233	int gret = 0, ret;
	234
	235	/* Block signals */
	236	ret = sigfillset(&sig_all_mask);
	237	if (ret)
	238	perror("Error in sigfillset");
	239	gret = (gret == 0) ? ret : gret;
	240	ret = sigprocmask(SIG_SETMASK, &sig_all_mask, saved_mask);
	241	if (ret)
	242	perror("Error in sigprocmask");
	243	gret = (gret == 0) ? ret : gret;
	244	return gret;
	245	}
	246
	247	static int forward_signals(pid_t pid, sigset_t *saved_mask)
	248	{
	249	struct sigaction act;
	250	int gret = 0, ret;
	251
	252	/* Forward SIGINT and SIGTERM */
	253	sigfwd_pid = pid;
	254	act.sa_sigaction = sighandler;
	255	act.sa_flags = SA_SIGINFO \| SA_RESTART;
	256	sigemptyset(&act.sa_mask);
	257	ret = sigaction(SIGINT, &act, NULL);
	258	if (ret)
	259	perror("Error in sigaction");
	260	gret = (gret == 0) ? ret : gret;
	261	ret = sigaction(SIGTERM, &act, NULL);
	262	if (ret)
	263	perror("Error in sigaction");
	264	gret = (gret == 0) ? ret : gret;
	265
	266	/* Reenable signals */
	267	ret = sigprocmask(SIG_SETMASK, saved_mask, NULL);
	268	if (ret)
	269	perror("Error in sigprocmask");
	270	gret = (gret == 0) ? ret : gret;
	271	return gret;
	272	}
273
274	int main(int argc, char *argv[])
275	{
276	uid_t euid, uid;
277	gid_t egid, gid;
278	pid_t pid;
279	int gret = 0, ret = 0;
280	int arg = 1;
281	sigset_t saved_mask;
282
8f48e913 MD	283	progname = argv[0];
	284
	285	if (argc < 2) {
	286	usage();
6f3a6fc5	287	return -ENOENT;
8f48e913	288	}
6f3a6fc5 MD	289
	290	euid = geteuid();
	291	uid = getuid();
	292	egid = getegid();
	293	gid = geteuid();
	294
	295	if (euid != 0 && uid != 0) {
8f48e913	296	printf("%s must be setuid root\n", progname);
6f3a6fc5 MD	297	return -EPERM;
	298	}
	299
	300	printf_dbg("euid: %d\n", euid);
	301	printf_dbg("uid: %d\n", uid);
	302	printf_dbg("egid: %d\n", egid);
	303	printf_dbg("gid: %d\n", gid);
	304
8f48e913 MD	305	ret = parse_options(argc, argv, &arg);
	306	if (ret)
	307	return ret;
6f3a6fc5 MD	308
	309	ret = init_trace_path();
	310	gret = (gret == 0) ? ret : gret;
	311
	312	ret = init_sighand(&saved_mask);
	313	gret = (gret == 0) ? ret : gret;
	314
	315	ret = start_tracing();
	316	if (ret)
	317	return ret;
	318
	319	pid = fork();
	320	if (pid > 0) { /* parent */
	321	int status;
	322
	323	ret = forward_signals(pid, &saved_mask);
	324	gret = (gret == 0) ? ret : gret;
	325	pid = wait(&status);
	326	if (pid == -1)
	327	gret = (gret == 0) ? -errno : gret;
	328
	329	ret = stop_tracing(uid, egid);
	330	gret = (gret == 0) ? ret : gret;
	331	ret = write_child_pid(pid, uid, egid);
	332	gret = (gret == 0) ? ret : gret;
	333	} else if (pid == 0) { /* child */
	334	/* Drop root euid before executing child program */
	335	seteuid(uid);
	336	/* Reenable signals */
	337	ret = sigprocmask(SIG_SETMASK, &saved_mask, NULL);
	338	if (ret) {
	339	perror("Error in sigprocmask");
	340	return ret;
	341	}
	342	ret = execvp(argv[arg], &argv[arg]);
	343	if (ret)
	344	perror("Execution error");
	345	return ret;
	346	} else { /* error */
	347	perror("Error in fork");
	348	return -errno;
	349	}
	350	return ret;
	351	}