1 /*
2 Copyright 2020 Northern.tech AS
3
4 This file is part of CFEngine 3 - written and maintained by Northern.tech AS.
5
6 This program is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; version 3.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
18
19 To the extent this program is licensed as part of the Enterprise
20 versions of CFEngine, the applicable Commercial Open Source License
21 (COSL) may apply to this file if you as a licensee so wish it. See
22 included file COSL.txt.
23 */
24
25 #include <enterprise_extension.h>
26
27 #include <known_dirs.h>
28 #include <misc_lib.h>
29
30 #include <pthread.h>
31
32 /*
33 * A note regarding the loading of the extension plugins:
34 *
35 * The extension plugin was originally statically linked into each agent,
36 * but was then refactored into plugins.
37 * Therefore, since it hasn't been written according to plugin guidelines,
38 * it is not safe to assume that we can unload it once we have
39 * loaded it, since it may allocate resources that are not freed. It is also
40 * not safe to assume that we can load it after initialization is complete
41 * (for example if the plugin is dropped into the directory after cf-serverd
42 * has already been running for some time), because some data structures may
43 * not have been initialized.
44 *
45 * Therefore, the load strategy is as follows:
46 *
47 * - If we find the plugin immediately, load it, and keep it loaded.
48 *
49 * - If we don't find the plugin, NEVER attempt to load it again afterwards.
50 *
51 * - Never unload the plugin.
52 *
53 * - Any installation/upgrade/removal of the plugin requires daemon restarts.
54 *
55 * - The exception is for testing (see getenv below).
56 */
57
58 #ifndef BUILTIN_EXTENSIONS
59
60 static bool enable_extension_libraries = true; /* GLOBAL_X */
61 static bool attempted_loading = false; /* GLOBAL_X */
62
extension_libraries_disable()63 void extension_libraries_disable()
64 {
65 if (attempted_loading)
66 {
67 ProgrammingError("extension_libraries_disable() MUST be called before any call to extension functions");
68 }
69 enable_extension_libraries = false;
70 }
71
extension_library_open(const char * name)72 void *extension_library_open(const char *name)
73 {
74 if (!enable_extension_libraries)
75 {
76 return NULL;
77 }
78
79 if (getenv("CFENGINE_TEST_OVERRIDE_EXTENSION_LIBRARY_DO_CLOSE") == NULL)
80 {
81 // Only do loading checks if we are not doing tests.
82 attempted_loading = true;
83 }
84
85 const char *dirs_to_try[3] = { NULL };
86 const char *dir = getenv("CFENGINE_TEST_OVERRIDE_EXTENSION_LIBRARY_DIR");
87 char lib[] = "/lib";
88 if (dir)
89 {
90 lib[0] = '\0';
91 dirs_to_try[0] = dir;
92 }
93 else
94 {
95 dirs_to_try[0] = GetWorkDir();
96 if (strcmp(WORKDIR, dirs_to_try[0]) != 0)
97 {
98 // try to load from the real WORKDIR in case GetWorkDir returned the local workdir to the user
99 // We try this because enterprise "make install" is in WORKDIR, not per user
100 dirs_to_try[1] = WORKDIR;
101 }
102 }
103
104 void *handle = NULL;
105 for (int i = 0; dirs_to_try[i]; i++)
106 {
107 char path[strlen(dirs_to_try[i]) + strlen(lib) + strlen(name) + 2];
108 xsnprintf(path, sizeof(path), "%s%s/%s", dirs_to_try[i], lib, name);
109
110 Log(LOG_LEVEL_DEBUG, "Trying to shlib_open extension plugin '%s' from '%s'", name, path);
111
112 handle = shlib_open(path);
113 if (handle)
114 {
115 Log(LOG_LEVEL_VERBOSE, "Successfully opened extension plugin '%s' from '%s'", name, path);
116 break;
117 }
118 else
119 {
120 const char *error;
121 if (errno == ENOENT)
122 {
123 error = "(not installed)";
124 }
125 else
126 {
127 error = GetErrorStr();
128 }
129 Log(LOG_LEVEL_VERBOSE, "Could not open extension plugin '%s' from '%s': %s", name, path, error);
130 }
131 }
132
133 if (!handle)
134 {
135 return handle;
136 }
137
138 // Version check, to avoid binary incompatible plugins.
139 const char * (*GetExtensionLibraryVersion)() = shlib_load(handle, "GetExtensionLibraryVersion");
140 if (!GetExtensionLibraryVersion)
141 {
142 Log(LOG_LEVEL_ERR, "Could not retrieve version from extension plugin (%s). Not loading the plugin.", name);
143 goto close_and_fail;
144 }
145
146 const char *plugin_version = GetExtensionLibraryVersion();
147 unsigned int bin_major, bin_minor, bin_patch;
148 unsigned int plug_major, plug_minor, plug_patch;
149 if (sscanf(VERSION, "%u.%u.%u", &bin_major, &bin_minor, &bin_patch) != 3)
150 {
151 Log(LOG_LEVEL_ERR, "Not able to extract version number from binary (%s). Not loading extension plugin.", name);
152 goto close_and_fail;
153 }
154 if (sscanf(plugin_version, "%u.%u.%u", &plug_major, &plug_minor, &plug_patch) != 3)
155 {
156 Log(LOG_LEVEL_ERR, "Not able to extract version number from plugin (%s). Not loading extension plugin.", name);
157 goto close_and_fail;
158 }
159
160 if (bin_major != plug_major || bin_minor != plug_minor || bin_patch != plug_patch)
161 {
162 Log(LOG_LEVEL_ERR, "Extension plugin version does not match CFEngine Community version "
163 "(CFEngine Community v%u.%u.%u, Extension (%s) v%u.%u.%u). Refusing to load it.",
164 bin_major, bin_minor, bin_patch, name, plug_major, plug_minor, plug_patch);
165 goto close_and_fail;
166 }
167
168 Log(LOG_LEVEL_VERBOSE, "Successfully loaded extension plugin '%s'", name);
169
170 return handle;
171
172 close_and_fail:
173 shlib_close(handle);
174 return NULL;
175 }
176
extension_library_close(void * handle)177 void extension_library_close(void *handle)
178 {
179 shlib_close(handle);
180 }
181
182 #endif // !BUILTIN_EXTENSIONS
183