1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "sandbox/linux/services/credentials.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/capability.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <vector>
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/files/scoped_file.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "sandbox/linux/services/proc_util.h"
#include "sandbox/linux/services/syscall_wrappers.h"
#include "sandbox/linux/system_headers/capability.h"
#include "sandbox/linux/tests/unit_tests.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace sandbox {
namespace {
struct CapFreeDeleter {
inline void operator()(cap_t cap) const {
int ret = cap_free(cap);
CHECK_EQ(0, ret);
}
};
// Wrapper to manage libcap2's cap_t type.
typedef scoped_ptr<typeof(*((cap_t)0)), CapFreeDeleter> ScopedCap;
bool WorkingDirectoryIsRoot() {
char current_dir[PATH_MAX];
char* cwd = getcwd(current_dir, sizeof(current_dir));
PCHECK(cwd);
if (strcmp("/", cwd)) return false;
// The current directory is the root. Add a few paranoid checks.
struct stat current;
CHECK_EQ(0, stat(".", ¤t));
struct stat parrent;
CHECK_EQ(0, stat("..", &parrent));
CHECK_EQ(current.st_dev, parrent.st_dev);
CHECK_EQ(current.st_ino, parrent.st_ino);
CHECK_EQ(current.st_mode, parrent.st_mode);
CHECK_EQ(current.st_uid, parrent.st_uid);
CHECK_EQ(current.st_gid, parrent.st_gid);
return true;
}
SANDBOX_TEST(Credentials, DropAllCaps) {
CHECK(Credentials::DropAllCapabilities());
CHECK(!Credentials::HasAnyCapability());
}
SANDBOX_TEST(Credentials, MoveToNewUserNS) {
CHECK(Credentials::DropAllCapabilities());
bool moved_to_new_ns = Credentials::MoveToNewUserNS();
fprintf(stdout,
"Unprivileged CLONE_NEWUSER supported: %s\n",
moved_to_new_ns ? "true." : "false.");
fflush(stdout);
if (!moved_to_new_ns) {
fprintf(stdout, "This kernel does not support unprivileged namespaces. "
"USERNS tests will succeed without running.\n");
fflush(stdout);
return;
}
CHECK(Credentials::HasAnyCapability());
CHECK(Credentials::DropAllCapabilities());
CHECK(!Credentials::HasAnyCapability());
}
SANDBOX_TEST(Credentials, CanCreateProcessInNewUserNS) {
CHECK(Credentials::DropAllCapabilities());
bool user_ns_supported = Credentials::CanCreateProcessInNewUserNS();
bool moved_to_new_ns = Credentials::MoveToNewUserNS();
CHECK_EQ(user_ns_supported, moved_to_new_ns);
}
SANDBOX_TEST(Credentials, UidIsPreserved) {
CHECK(Credentials::DropAllCapabilities());
uid_t old_ruid, old_euid, old_suid;
gid_t old_rgid, old_egid, old_sgid;
PCHECK(0 == getresuid(&old_ruid, &old_euid, &old_suid));
PCHECK(0 == getresgid(&old_rgid, &old_egid, &old_sgid));
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS()) return;
uid_t new_ruid, new_euid, new_suid;
PCHECK(0 == getresuid(&new_ruid, &new_euid, &new_suid));
CHECK(old_ruid == new_ruid);
CHECK(old_euid == new_euid);
CHECK(old_suid == new_suid);
gid_t new_rgid, new_egid, new_sgid;
PCHECK(0 == getresgid(&new_rgid, &new_egid, &new_sgid));
CHECK(old_rgid == new_rgid);
CHECK(old_egid == new_egid);
CHECK(old_sgid == new_sgid);
}
bool NewUserNSCycle() {
if (!Credentials::MoveToNewUserNS() ||
!Credentials::HasAnyCapability() ||
!Credentials::DropAllCapabilities() ||
Credentials::HasAnyCapability()) {
return false;
}
return true;
}
SANDBOX_TEST(Credentials, NestedUserNS) {
CHECK(Credentials::DropAllCapabilities());
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS()) return;
CHECK(Credentials::DropAllCapabilities());
// As of 3.12, the kernel has a limit of 32. See create_user_ns().
const int kNestLevel = 10;
for (int i = 0; i < kNestLevel; ++i) {
CHECK(NewUserNSCycle()) << "Creating new user NS failed at iteration "
<< i << ".";
}
}
// Test the WorkingDirectoryIsRoot() helper.
SANDBOX_TEST(Credentials, CanDetectRoot) {
PCHECK(0 == chdir("/proc/"));
CHECK(!WorkingDirectoryIsRoot());
PCHECK(0 == chdir("/"));
CHECK(WorkingDirectoryIsRoot());
}
// Disabled on ASAN because of crbug.com/451603.
SANDBOX_TEST(Credentials, DISABLE_ON_ASAN(DropFileSystemAccessIsSafe)) {
CHECK(Credentials::DropAllCapabilities());
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS()) return;
CHECK(Credentials::DropFileSystemAccess(ProcUtil::OpenProc().get()));
CHECK(!base::DirectoryExists(base::FilePath("/proc")));
CHECK(WorkingDirectoryIsRoot());
CHECK(base::IsDirectoryEmpty(base::FilePath("/")));
// We want the chroot to never have a subdirectory. A subdirectory
// could allow a chroot escape.
CHECK_NE(0, mkdir("/test", 0700));
}
// Check that after dropping filesystem access and dropping privileges
// it is not possible to regain capabilities.
SANDBOX_TEST(Credentials, DISABLE_ON_ASAN(CannotRegainPrivileges)) {
base::ScopedFD proc_fd(ProcUtil::OpenProc());
CHECK(Credentials::DropAllCapabilities(proc_fd.get()));
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS()) return;
CHECK(Credentials::DropFileSystemAccess(proc_fd.get()));
CHECK(Credentials::DropAllCapabilities(proc_fd.get()));
// The kernel should now prevent us from regaining capabilities because we
// are in a chroot.
CHECK(!Credentials::CanCreateProcessInNewUserNS());
CHECK(!Credentials::MoveToNewUserNS());
}
SANDBOX_TEST(Credentials, SetCapabilities) {
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS())
return;
base::ScopedFD proc_fd(ProcUtil::OpenProc());
CHECK(Credentials::HasCapability(Credentials::Capability::SYS_ADMIN));
CHECK(Credentials::HasCapability(Credentials::Capability::SYS_CHROOT));
std::vector<Credentials::Capability> caps;
caps.push_back(Credentials::Capability::SYS_CHROOT);
CHECK(Credentials::SetCapabilities(proc_fd.get(), caps));
CHECK(!Credentials::HasCapability(Credentials::Capability::SYS_ADMIN));
CHECK(Credentials::HasCapability(Credentials::Capability::SYS_CHROOT));
const std::vector<Credentials::Capability> no_caps;
CHECK(Credentials::SetCapabilities(proc_fd.get(), no_caps));
CHECK(!Credentials::HasAnyCapability());
}
SANDBOX_TEST(Credentials, SetCapabilitiesAndChroot) {
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS())
return;
base::ScopedFD proc_fd(ProcUtil::OpenProc());
CHECK(Credentials::HasCapability(Credentials::Capability::SYS_CHROOT));
PCHECK(chroot("/") == 0);
std::vector<Credentials::Capability> caps;
caps.push_back(Credentials::Capability::SYS_CHROOT);
CHECK(Credentials::SetCapabilities(proc_fd.get(), caps));
PCHECK(chroot("/") == 0);
CHECK(Credentials::DropAllCapabilities());
PCHECK(chroot("/") == -1 && errno == EPERM);
}
SANDBOX_TEST(Credentials, SetCapabilitiesMatchesLibCap2) {
// Probably missing kernel support.
if (!Credentials::MoveToNewUserNS())
return;
base::ScopedFD proc_fd(ProcUtil::OpenProc());
std::vector<Credentials::Capability> caps;
caps.push_back(Credentials::Capability::SYS_CHROOT);
CHECK(Credentials::SetCapabilities(proc_fd.get(), caps));
ScopedCap actual_cap(cap_get_proc());
PCHECK(actual_cap != nullptr);
ScopedCap expected_cap(cap_init());
PCHECK(expected_cap != nullptr);
const cap_value_t allowed_cap = CAP_SYS_CHROOT;
for (const cap_flag_t flag : {CAP_EFFECTIVE, CAP_PERMITTED}) {
PCHECK(cap_set_flag(expected_cap.get(), flag, 1, &allowed_cap, CAP_SET) ==
0);
}
CHECK_EQ(0, cap_compare(expected_cap.get(), actual_cap.get()));
}
} // namespace.
} // namespace sandbox.
|
