1 /*
2  * Copyright (C) 2019 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 #define LOG_TAG "fsverity_init"
18 
19 #include <sys/types.h>
20 
21 #include <filesystem>
22 #include <string>
23 
24 #include <android-base/file.h>
25 #include <android-base/logging.h>
26 #include <android-base/properties.h>
27 #include <android-base/strings.h>
28 #include <log/log.h>
29 #include <mini_keyctl_utils.h>
30 
31 bool LoadKeyToKeyring(key_serial_t keyring_id, const char* desc, const char* data, size_t size) {
32     key_serial_t key = add_key("asymmetric", desc, data, size, keyring_id);
33     if (key < 0) {
34         PLOG(ERROR) << "Failed to add key";
35         return false;
36     }
37     return true;
38 }
39 
40 void LoadKeyFromStdin(key_serial_t keyring_id, const char* keyname) {
41     std::string content;
42     if (!android::base::ReadFdToString(STDIN_FILENO, &content)) {
43         LOG(ERROR) << "Failed to read key from stdin";
44         return;
45     }
46     if (!LoadKeyToKeyring(keyring_id, keyname, content.c_str(), content.size())) {
47         LOG(ERROR) << "Failed to load key from stdin";
48     }
49 }
50 
51 void LoadKeyFromFile(key_serial_t keyring_id, const char* keyname, const std::string& path) {
52     LOG(INFO) << "LoadKeyFromFile path=" << path << " keyname=" << keyname;
53     std::string content;
54     if (!android::base::ReadFileToString(path, &content)) {
55         LOG(ERROR) << "Failed to read key from " << path;
56         return;
57     }
58     if (!LoadKeyToKeyring(keyring_id, keyname, content.c_str(), content.size())) {
59         LOG(ERROR) << "Failed to load key from " << path;
60     }
61 }
62 
63 void LoadKeyFromDirectory(key_serial_t keyring_id, const char* keyname_prefix, const char* dir) {
64     if (!std::filesystem::exists(dir)) {
65         return;
66     }
67     int counter = 0;
68     for (const auto& entry : std::filesystem::directory_iterator(dir)) {
69         if (!android::base::EndsWithIgnoreCase(entry.path().c_str(), ".der")) continue;
70         std::string keyname = keyname_prefix + std::to_string(counter);
71         counter++;
72         LoadKeyFromFile(keyring_id, keyname.c_str(), entry.path());
73     }
74 }
75 
76 void LoadKeyFromVerifiedPartitions(key_serial_t keyring_id) {
77     // NB: Directories need to be synced with FileIntegrityService.java in
78     // frameworks/base.
79     LoadKeyFromDirectory(keyring_id, "fsv_system_", "/system/etc/security/fsverity");
80     LoadKeyFromDirectory(keyring_id, "fsv_product_", "/product/etc/security/fsverity");
81 }
82 
83 int main(int argc, const char** argv) {
84     if (argc < 2) {
85         LOG(ERROR) << "Not enough arguments";
86         return -1;
87     }
88 
89     key_serial_t keyring_id = android::GetKeyringId(".fs-verity");
90     if (keyring_id < 0) {
91         LOG(ERROR) << "Failed to find .fs-verity keyring id";
92         return -1;
93     }
94 
95     const std::string_view command = argv[1];
96 
97     if (command == "--load-verified-keys") {
98         LoadKeyFromVerifiedPartitions(keyring_id);
99     } else if (command == "--load-extra-key") {
100         if (argc != 3) {
101             LOG(ERROR) << "--load-extra-key requires <key_name> argument.";
102             return -1;
103         }
104         LoadKeyFromStdin(keyring_id, argv[2]);
105     } else if (command == "--lock") {
106         // Requires files backed by fs-verity to be verified with a key in .fs-verity
107         // keyring.
108         if (!android::base::WriteStringToFile("1", "/proc/sys/fs/verity/require_signatures")) {
109             PLOG(ERROR) << "Failed to enforce fs-verity signature";
110         }
111 
112         if (!android::base::GetBoolProperty("ro.debuggable", false)) {
113             if (keyctl_restrict_keyring(keyring_id, nullptr, nullptr) < 0) {
114                 PLOG(ERROR) << "Cannot restrict .fs-verity keyring";
115             }
116         }
117     } else {
118         LOG(ERROR) << "Unknown argument(s).";
119         return -1;
120     }
121 
122     return 0;
123 }
124