1 /*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "ext4_utils/ext4_crypt_init_extensions.h"
18
19 #include <dirent.h>
20 #include <errno.h>
21 #include <sys/mount.h>
22 #include <sys/stat.h>
23 #include <unistd.h>
24
25 #include <string>
26 #include <vector>
27
28 #include <android-base/file.h>
29 #include <android-base/logging.h>
30 #include <android-base/stringprintf.h>
31 #include <android-base/strings.h>
32 #include <cutils/properties.h>
33 #include <cutils/sockets.h>
34 #include <logwrap/logwrap.h>
35
36 #include "ext4_utils/ext4_crypt.h"
37 #include "ext4_utils/key_control.h"
38
39 #define TAG "ext4_utils"
40
41 static const std::string arbitrary_sequence_number = "42";
42 static const int vold_command_timeout_ms = 60 * 1000;
43
e4crypt_install_keyring()44 int e4crypt_install_keyring()
45 {
46 key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
47 KEY_SPEC_SESSION_KEYRING);
48
49 if (device_keyring == -1) {
50 PLOG(ERROR) << "Failed to create keyring";
51 return -1;
52 }
53
54 LOG(INFO) << "Keyring created with id " << device_keyring << " in process " << getpid();
55
56 return 0;
57 }
58
e4crypt_do_init_user0()59 int e4crypt_do_init_user0()
60 {
61 const char* argv[] = { "/system/bin/vdc", "--wait", "cryptfs", "init_user0" };
62 int rc = android_fork_execvp_ext(arraysize(argv), (char**) argv, NULL, false,
63 LOG_KLOG, false, NULL, NULL, 0);
64 LOG(INFO) << "init_user0 result: " << rc;
65 return rc;
66 }
67
e4crypt_set_directory_policy(const char * dir)68 int e4crypt_set_directory_policy(const char* dir)
69 {
70 // Only set policy on first level /data directories
71 // To make this less restrictive, consider using a policy file.
72 // However this is overkill for as long as the policy is simply
73 // to apply a global policy to all /data folders created via makedir
74 if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
75 return 0;
76 }
77
78 // Special case various directories that must not be encrypted,
79 // often because their subdirectories must be encrypted.
80 // This isn't a nice way to do this, see b/26641735
81 std::vector<std::string> directories_to_exclude = {
82 "lost+found",
83 "system_ce", "system_de",
84 "misc_ce", "misc_de",
85 "media",
86 "data", "user", "user_de",
87 };
88 std::string prefix = "/data/";
89 for (auto d: directories_to_exclude) {
90 if ((prefix + d) == dir) {
91 LOG(INFO) << "Not setting policy on " << dir;
92 return 0;
93 }
94 }
95
96 std::string ref_filename = std::string("/data") + e4crypt_key_ref;
97 std::string policy;
98 if (!android::base::ReadFileToString(ref_filename, &policy)) {
99 LOG(ERROR) << "Unable to read system policy to set on " << dir;
100 return -1;
101 }
102
103 auto type_filename = std::string("/data") + e4crypt_key_mode;
104 std::string modestring;
105 if (!android::base::ReadFileToString(type_filename, &modestring)) {
106 LOG(ERROR) << "Cannot read mode";
107 }
108
109 std::vector<std::string> modes = android::base::Split(modestring, ":");
110
111 if (modes.size() < 1 || modes.size() > 2) {
112 LOG(ERROR) << "Invalid encryption mode string: " << modestring;
113 return -1;
114 }
115
116 LOG(INFO) << "Setting policy on " << dir;
117 int result = e4crypt_policy_ensure(dir, policy.c_str(), policy.length(),
118 modes[0].c_str(),
119 modes.size() >= 2 ?
120 modes[1].c_str() : "aes-256-cts");
121 if (result) {
122 LOG(ERROR) << android::base::StringPrintf(
123 "Setting %02x%02x%02x%02x policy on %s failed!",
124 policy[0], policy[1], policy[2], policy[3], dir);
125 return -1;
126 }
127
128 return 0;
129 }
130