[lttng-ust.git] / src / common / getenv.c

/*
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 * Copyright (C) 2017 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <stdlib.h>
#include <unistd.h>
#include <stdbool.h>
#include <stddef.h>
#include <sys/types.h>
#include <urcu/system.h>
#include "common/logging.h"
#include "common/macros.h"
#include "common/getenv.h"

enum lttng_env_secure {
	LTTNG_ENV_SECURE,
	LTTNG_ENV_NOT_SECURE,
};

struct lttng_env {
	const char *key;
	enum lttng_env_secure secure;
	char *value;
};

static
int lttng_ust_getenv_is_init = 0;

static struct lttng_env lttng_env[] = {
	/*
	 * LTTNG_UST_DEBUG is used directly by snprintf, because it
	 * needs to be already set for ERR() used in
	 * lttng_ust_getenv_init().
	 */
	{ "LTTNG_UST_DEBUG", LTTNG_ENV_NOT_SECURE, NULL, },

	/* Env. var. which can be used in setuid/setgid executables. */
	{ "LTTNG_UST_WITHOUT_BADDR_STATEDUMP", LTTNG_ENV_NOT_SECURE, NULL, },
	{ "LTTNG_UST_REGISTER_TIMEOUT", LTTNG_ENV_NOT_SECURE, NULL, },

	/* Env. var. which are not fetched in setuid/setgid executables. */
	{ "LTTNG_UST_CLOCK_PLUGIN", LTTNG_ENV_SECURE, NULL, },
	{ "LTTNG_UST_GETCPU_PLUGIN", LTTNG_ENV_SECURE, NULL, },
	{ "LTTNG_UST_ALLOW_BLOCKING", LTTNG_ENV_SECURE, NULL, },
	{ "HOME", LTTNG_ENV_SECURE, NULL, },
	{ "LTTNG_HOME", LTTNG_ENV_SECURE, NULL, },
};

static
int lttng_is_setuid_setgid(void)
{
	return geteuid() != getuid() || getegid() != getgid();
}

/*
 * Wrapper over getenv that will only return the values of whitelisted
 * environment variables when the current process is setuid and/or setgid.
 */
char *lttng_ust_getenv(const char *name)
{
	size_t i;
	struct lttng_env *e;
	bool found = false;

	/*
	 * Perform lazy initialization of lttng_ust_getenv for early use
	 * by library constructors.
	 */
	lttng_ust_getenv_init();

	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
		e = &lttng_env[i];

		if (strcmp(e->key, name) == 0) {
			found = true;
			break;
		}
	}
	if (!found) {
		return NULL;
	}
	return e->value;
}

void lttng_ust_getenv_init(void)
{
	size_t i;

	if (CMM_LOAD_SHARED(lttng_ust_getenv_is_init))
		return;

	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
		struct lttng_env *e = &lttng_env[i];

		if (e->secure == LTTNG_ENV_SECURE && lttng_is_setuid_setgid()) {
			ERR("Getting environment variable '%s' from setuid/setgid binary refused for security reasons.",
				e->key);
			continue;
		}
		e->value = getenv(e->key);
	}
	CMM_STORE_SHARED(lttng_ust_getenv_is_init, 1);
}
Commit	Line	Data
6f626d28	1	/*
c0c0989a	2	* SPDX-License-Identifier: LGPL-2.1-only
6f626d28	3	*
c0c0989a	4	* Copyright (C) 2017 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6f626d28 MD	5	*/
	6
	7	#include <stdlib.h>
	8	#include <unistd.h>
	9	#include <stdbool.h>
b4051ad8	10	#include <stddef.h>
6f626d28	11	#include <sys/types.h>
910dcd72	12	#include <urcu/system.h>
9d315d6d MJ	13	#include "common/logging.h"
9d315d6d MJ	14	#include "common/macros.h"
910dcd72	15	#include "common/getenv.h"
6f626d28 MD	16
	17	enum lttng_env_secure {
	18	LTTNG_ENV_SECURE,
	19	LTTNG_ENV_NOT_SECURE,
	20	};
	21
	22	struct lttng_env {
	23	const char *key;
	24	enum lttng_env_secure secure;
	25	char *value;
	26	};
	27
910dcd72 MJ	28	static
	29	int lttng_ust_getenv_is_init = 0;
	30
6f626d28 MD	31	static struct lttng_env lttng_env[] = {
	32	/*
	33	* LTTNG_UST_DEBUG is used directly by snprintf, because it
	34	* needs to be already set for ERR() used in
	35	* lttng_ust_getenv_init().
	36	*/
	37	{ "LTTNG_UST_DEBUG", LTTNG_ENV_NOT_SECURE, NULL, },
	38
	39	/* Env. var. which can be used in setuid/setgid executables. */
	40	{ "LTTNG_UST_WITHOUT_BADDR_STATEDUMP", LTTNG_ENV_NOT_SECURE, NULL, },
	41	{ "LTTNG_UST_REGISTER_TIMEOUT", LTTNG_ENV_NOT_SECURE, NULL, },
	42
	43	/* Env. var. which are not fetched in setuid/setgid executables. */
	44	{ "LTTNG_UST_CLOCK_PLUGIN", LTTNG_ENV_SECURE, NULL, },
	45	{ "LTTNG_UST_GETCPU_PLUGIN", LTTNG_ENV_SECURE, NULL, },
b2c5f61a	46	{ "LTTNG_UST_ALLOW_BLOCKING", LTTNG_ENV_SECURE, NULL, },
6f626d28 MD	47	{ "HOME", LTTNG_ENV_SECURE, NULL, },
	48	{ "LTTNG_HOME", LTTNG_ENV_SECURE, NULL, },
	49	};
	50
	51	static
	52	int lttng_is_setuid_setgid(void)
	53	{
	54	return geteuid() != getuid() \|\| getegid() != getgid();
	55	}
	56
910dcd72 MJ	57	/*
	58	* Wrapper over getenv that will only return the values of whitelisted
	59	* environment variables when the current process is setuid and/or setgid.
	60	*/
4c41b460	61	char lttng_ust_getenv(const char name)
6f626d28 MD	62	{
	63	size_t i;
	64	struct lttng_env *e;
	65	bool found = false;
	66
407937dc MD	67	/*
	68	* Perform lazy initialization of lttng_ust_getenv for early use
	69	* by library constructors.
	70	*/
	71	lttng_ust_getenv_init();
910dcd72	72
6f626d28 MD	73	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
	74	e = &lttng_env[i];
	75
	76	if (strcmp(e->key, name) == 0) {
	77	found = true;
	78	break;
	79	}
	80	}
	81	if (!found) {
	82	return NULL;
	83	}
	84	return e->value;
	85	}
	86
	87	void lttng_ust_getenv_init(void)
	88	{
	89	size_t i;
	90
910dcd72 MJ	91	if (CMM_LOAD_SHARED(lttng_ust_getenv_is_init))
	92	return;
	93
6f626d28 MD	94	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
	95	struct lttng_env *e = &lttng_env[i];
	96
	97	if (e->secure == LTTNG_ENV_SECURE && lttng_is_setuid_setgid()) {
	98	ERR("Getting environment variable '%s' from setuid/setgid binary refused for security reasons.",
	99	e->key);
	100	continue;
	101	}
	102	e->value = getenv(e->key);
	103	}
910dcd72	104	CMM_STORE_SHARED(lttng_ust_getenv_is_init, 1);
6f626d28	105	}