[lttng-ust.git] / liblttng-ust / 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 <usterr-signal-safe.h>
#include <helper.h>
#include "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 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();
}

char *lttng_getenv(const char *name)
{
	size_t i;
	struct lttng_env *e;
	bool found = false;

	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;

	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);
	}
}
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 MD	11	#include <sys/types.h>
	12	#include <usterr-signal-safe.h>
	13	#include <helper.h>
	14	#include "getenv.h"
	15
	16	enum lttng_env_secure {
	17	LTTNG_ENV_SECURE,
	18	LTTNG_ENV_NOT_SECURE,
	19	};
	20
	21	struct lttng_env {
	22	const char *key;
	23	enum lttng_env_secure secure;
	24	char *value;
	25	};
	26
	27	static struct lttng_env lttng_env[] = {
	28	/*
	29	* LTTNG_UST_DEBUG is used directly by snprintf, because it
	30	* needs to be already set for ERR() used in
	31	* lttng_ust_getenv_init().
	32	*/
	33	{ "LTTNG_UST_DEBUG", LTTNG_ENV_NOT_SECURE, NULL, },
	34
	35	/* Env. var. which can be used in setuid/setgid executables. */
	36	{ "LTTNG_UST_WITHOUT_BADDR_STATEDUMP", LTTNG_ENV_NOT_SECURE, NULL, },
	37	{ "LTTNG_UST_REGISTER_TIMEOUT", LTTNG_ENV_NOT_SECURE, NULL, },
	38
	39	/* Env. var. which are not fetched in setuid/setgid executables. */
	40	{ "LTTNG_UST_CLOCK_PLUGIN", LTTNG_ENV_SECURE, NULL, },
	41	{ "LTTNG_UST_GETCPU_PLUGIN", LTTNG_ENV_SECURE, NULL, },
b2c5f61a	42	{ "LTTNG_UST_ALLOW_BLOCKING", LTTNG_ENV_SECURE, NULL, },
6f626d28 MD	43	{ "HOME", LTTNG_ENV_SECURE, NULL, },
	44	{ "LTTNG_HOME", LTTNG_ENV_SECURE, NULL, },
	45	};
	46
	47	static
	48	int lttng_is_setuid_setgid(void)
	49	{
	50	return geteuid() != getuid() \|\| getegid() != getgid();
	51	}
	52
	53	char lttng_getenv(const char name)
	54	{
	55	size_t i;
	56	struct lttng_env *e;
	57	bool found = false;
	58
	59	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
	60	e = &lttng_env[i];
	61
	62	if (strcmp(e->key, name) == 0) {
	63	found = true;
	64	break;
	65	}
	66	}
	67	if (!found) {
	68	return NULL;
	69	}
	70	return e->value;
	71	}
	72
	73	void lttng_ust_getenv_init(void)
	74	{
	75	size_t i;
	76
	77	for (i = 0; i < LTTNG_ARRAY_SIZE(lttng_env); i++) {
	78	struct lttng_env *e = &lttng_env[i];
	79
	80	if (e->secure == LTTNG_ENV_SECURE && lttng_is_setuid_setgid()) {
	81	ERR("Getting environment variable '%s' from setuid/setgid binary refused for security reasons.",
	82	e->key);
	83	continue;
	84	}
	85	e->value = getenv(e->key);
	86	}
	87	}