Fix: pass private data to context callbacks
[lttng-ust.git] / liblttng-ust / getenv.c
1 /*
2 * SPDX-License-Identifier: LGPL-2.1-only
3 *
4 * Copyright (C) 2017 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 */
6
7 #include <stdlib.h>
8 #include <unistd.h>
9 #include <stdbool.h>
10 #include <stddef.h>
11 #include <sys/types.h>
12 #include <usterr-signal-safe.h>
13 #include <ust-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, },
42 { "LTTNG_UST_ALLOW_BLOCKING", LTTNG_ENV_SECURE, NULL, },
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_ust_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 }
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