1 /*
2 * Copyright (C) 2016 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "linker_namespaces.h"
30 #include "linker_globals.h"
31 #include "linker_soinfo.h"
32 #include "linker_utils.h"
33
34 #include <dlfcn.h>
35
36 // Given an absolute path, can this library be loaded into this namespace?
is_accessible(const std::string & file)37 bool android_namespace_t::is_accessible(const std::string& file) {
38 if (!is_isolated_) {
39 return true;
40 }
41
42 if (!allowed_libs_.empty()) {
43 const char *lib_name = basename(file.c_str());
44 if (std::find(allowed_libs_.begin(), allowed_libs_.end(), lib_name) == allowed_libs_.end()) {
45 return false;
46 }
47 }
48
49 for (const auto& dir : ld_library_paths_) {
50 if (file_is_in_dir(file, dir)) {
51 return true;
52 }
53 }
54
55 for (const auto& dir : default_library_paths_) {
56 if (file_is_in_dir(file, dir)) {
57 return true;
58 }
59 }
60
61 for (const auto& dir : permitted_paths_) {
62 if (file_is_under_dir(file, dir)) {
63 return true;
64 }
65 }
66
67 return false;
68 }
69
70 // Are symbols from this shared object accessible for symbol lookups in a library from this
71 // namespace?
is_accessible(soinfo * s)72 bool android_namespace_t::is_accessible(soinfo* s) {
73 auto is_accessible_ftor = [this] (soinfo* si, bool allow_secondary) {
74 // This is workaround for apps hacking into soinfo list.
75 // and inserting their own entries into it. (http://b/37191433)
76 if (!si->has_min_version(3)) {
77 DL_WARN("Warning: invalid soinfo version for \"%s\" (assuming inaccessible)",
78 si->get_soname());
79 return false;
80 }
81
82 if (si->get_primary_namespace() == this) {
83 return true;
84 }
85
86 // When we're looking up symbols, we want to search libraries from the same namespace (whether
87 // the namespace membership is primary or secondary), but we also want to search the immediate
88 // dependencies of libraries in our namespace. (e.g. Supposing that libapp.so -> libandroid.so
89 // crosses a namespace boundary, we want to search libandroid.so but not any of libandroid.so's
90 // dependencies).
91 //
92 // Some libraries may be present in this namespace via the secondary namespace list:
93 // - the executable
94 // - LD_PRELOAD and DF_1_GLOBAL libraries
95 // - libraries inherited during dynamic namespace creation (e.g. because of
96 // RTLD_GLOBAL / DF_1_GLOBAL / ANDROID_NAMESPACE_TYPE_SHARED)
97 //
98 // When a library's membership is secondary, we want to search its symbols, but not the symbols
99 // of its dependencies. The executable may depend on internal system libraries which should not
100 // be searched.
101 if (allow_secondary) {
102 const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
103 if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
104 return true;
105 }
106 }
107
108 return false;
109 };
110
111 if (is_accessible_ftor(s, true)) {
112 return true;
113 }
114
115 return !s->get_parents().visit([&](soinfo* si) {
116 return !is_accessible_ftor(si, false);
117 });
118 }
119
120 // TODO: this is slightly unusual way to construct
121 // the global group for relocation. Not every RTLD_GLOBAL
122 // library is included in this group for backwards-compatibility
123 // reasons.
124 //
125 // This group consists of the main executable, LD_PRELOADs
126 // and libraries with the DF_1_GLOBAL flag set.
get_global_group()127 soinfo_list_t android_namespace_t::get_global_group() {
128 soinfo_list_t global_group;
129 soinfo_list().for_each([&](soinfo* si) {
130 if ((si->get_dt_flags_1() & DF_1_GLOBAL) != 0) {
131 global_group.push_back(si);
132 }
133 });
134
135 return global_group;
136 }
137
138 // This function provides a list of libraries to be shared
139 // by the namespace. For the default namespace this is the global
140 // group (see get_global_group). For all others this is a group
141 // of RTLD_GLOBAL libraries (which includes the global group from
142 // the default namespace).
get_shared_group()143 soinfo_list_t android_namespace_t::get_shared_group() {
144 if (this == &g_default_namespace) {
145 return get_global_group();
146 }
147
148 soinfo_list_t shared_group;
149 soinfo_list().for_each([&](soinfo* si) {
150 if ((si->get_rtld_flags() & RTLD_GLOBAL) != 0) {
151 shared_group.push_back(si);
152 }
153 });
154
155 return shared_group;
156 }
157