gatekeeperd.cpp revision 33dfdc7bbc48911a8a5324b16b05e492ae653d76 
1/*
2 * Copyright (C) 2015 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 "gatekeeperd"
18
19#include "IGateKeeperService.h"
20
21#include <errno.h>
22#include <stdint.h>
23#include <inttypes.h>
24#include <fcntl.h>
25#include <unistd.h>
26
27#include <cutils/log.h>
28#include <utils/Log.h>
29
30#include <binder/IPCThreadState.h>
31#include <binder/IServiceManager.h>
32#include <binder/PermissionCache.h>
33#include <utils/String16.h>
34
35#include <keystore/IKeystoreService.h>
36#include <keystore/keystore.h> // For error code
37#include <gatekeeper/password_handle.h> // for password_handle_t
38#include <hardware/gatekeeper.h>
39#include <hardware/hw_auth_token.h>
40
41#include "SoftGateKeeperDevice.h"
42
43namespace android {
44
45static const String16 KEYGUARD_PERMISSION("android.permission.ACCESS_KEYGUARD_SECURE_STORAGE");
46static const String16 DUMP_PERMISSION("android.permission.DUMP");
47
48class GateKeeperProxy : public BnGateKeeperService {
49public:
50    GateKeeperProxy() {
51        int ret = hw_get_module_by_class(GATEKEEPER_HARDWARE_MODULE_ID, NULL, &module);
52        if (ret < 0) {
53            ALOGW("falling back to software GateKeeper");
54            soft_device.reset(new SoftGateKeeperDevice());
55        } else {
56            ret = gatekeeper_open(module, &device);
57            if (ret < 0)
58                LOG_ALWAYS_FATAL_IF(ret < 0, "Unable to open GateKeeper HAL");
59        }
60    }
61
62    virtual ~GateKeeperProxy() {
63        if (device) gatekeeper_close(device);
64    }
65
66    void store_sid(uint32_t uid, uint64_t sid) {
67        char filename[21];
68        sprintf(filename, "%u", uid);
69        int fd = open(filename, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR);
70        if (fd < 0) {
71            ALOGE("could not open file: %s: %s", filename, strerror(errno));
72            return;
73        }
74        write(fd, &sid, sizeof(sid));
75        close(fd);
76    }
77
78    void maybe_store_sid(uint32_t uid, uint64_t sid) {
79        char filename[21];
80        sprintf(filename, "%u", uid);
81        if (access(filename, F_OK) == -1) {
82            store_sid(uid, sid);
83        }
84    }
85
86    uint64_t read_sid(uint32_t uid) {
87        char filename[21];
88        uint64_t sid;
89        sprintf(filename, "%u", uid);
90        int fd = open(filename, O_RDONLY);
91        if (fd < 0) return 0;
92        read(fd, &sid, sizeof(sid));
93        return sid;
94    }
95
96    void clear_sid(uint32_t uid) {
97        char filename[21];
98        sprintf(filename, "%u", uid);
99        if (remove(filename) < 0) {
100            ALOGE("%s: could not remove file [%s], attempting 0 write", __func__, strerror(errno));
101            store_sid(uid, 0);
102        }
103    }
104
105    virtual status_t enroll(uint32_t uid,
106            const uint8_t *current_password_handle, uint32_t current_password_handle_length,
107            const uint8_t *current_password, uint32_t current_password_length,
108            const uint8_t *desired_password, uint32_t desired_password_length,
109            uint8_t **enrolled_password_handle, uint32_t *enrolled_password_handle_length) {
110        IPCThreadState* ipc = IPCThreadState::self();
111        const int calling_pid = ipc->getCallingPid();
112        const int calling_uid = ipc->getCallingUid();
113        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
114            return PERMISSION_DENIED;
115        }
116
117        // need a desired password to enroll
118        if (desired_password_length == 0) return -EINVAL;
119
120        int ret;
121        if (device) {
122            ret = device->enroll(device, uid,
123                    current_password_handle, current_password_handle_length,
124                    current_password, current_password_length,
125                    desired_password, desired_password_length,
126                    enrolled_password_handle, enrolled_password_handle_length);
127        } else {
128            ret = soft_device->enroll(uid,
129                    current_password_handle, current_password_handle_length,
130                    current_password, current_password_length,
131                    desired_password, desired_password_length,
132                    enrolled_password_handle, enrolled_password_handle_length);
133        }
134
135        if (ret >= 0) {
136            gatekeeper::password_handle_t *handle =
137                    reinterpret_cast<gatekeeper::password_handle_t *>(*enrolled_password_handle);
138            store_sid(uid, handle->user_id);
139            return NO_ERROR;
140        }
141        return UNKNOWN_ERROR;
142    }
143
144    virtual status_t verify(uint32_t uid,
145            const uint8_t *enrolled_password_handle, uint32_t enrolled_password_handle_length,
146            const uint8_t *provided_password, uint32_t provided_password_length) {
147        uint8_t *auth_token;
148        uint32_t auth_token_length;
149        return verifyChallenge(uid, 0, enrolled_password_handle, enrolled_password_handle_length,
150                provided_password, provided_password_length,
151                &auth_token, &auth_token_length);
152    }
153
154    virtual status_t verifyChallenge(uint32_t uid, uint64_t challenge,
155            const uint8_t *enrolled_password_handle, uint32_t enrolled_password_handle_length,
156            const uint8_t *provided_password, uint32_t provided_password_length,
157            uint8_t **auth_token, uint32_t *auth_token_length) {
158        IPCThreadState* ipc = IPCThreadState::self();
159        const int calling_pid = ipc->getCallingPid();
160        const int calling_uid = ipc->getCallingUid();
161        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
162            return PERMISSION_DENIED;
163        }
164
165        // can't verify if we're missing either param
166        if ((enrolled_password_handle_length | provided_password_length) == 0)
167            return -EINVAL;
168
169        int ret;
170        if (device) {
171            ret = device->verify(device, uid, challenge,
172                enrolled_password_handle, enrolled_password_handle_length,
173                provided_password, provided_password_length, auth_token, auth_token_length);
174        } else {
175            ret = soft_device->verify(uid, challenge,
176                enrolled_password_handle, enrolled_password_handle_length,
177                provided_password, provided_password_length, auth_token, auth_token_length);
178        }
179
180        if (ret >= 0 && *auth_token != NULL && *auth_token_length > 0) {
181            // TODO: cache service?
182            sp<IServiceManager> sm = defaultServiceManager();
183            sp<IBinder> binder = sm->getService(String16("android.security.keystore"));
184            sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
185            if (service != NULL) {
186                status_t ret = service->addAuthToken(*auth_token, *auth_token_length);
187                if (ret != ResponseCode::NO_ERROR) {
188                    ALOGE("Falure sending auth token to KeyStore: %d", ret);
189                }
190            } else {
191                ALOGE("Unable to communicate with KeyStore");
192            }
193        }
194
195        if (ret >= 0) {
196            maybe_store_sid(uid, reinterpret_cast<const gatekeeper::password_handle_t *>(
197                        enrolled_password_handle)->user_id);
198            return NO_ERROR;
199        }
200
201        return UNKNOWN_ERROR;
202    }
203
204    virtual uint64_t getSecureUserId(uint32_t uid) {
205        return read_sid(uid);
206    }
207
208    virtual void clearSecureUserId(uint32_t uid) {
209        IPCThreadState* ipc = IPCThreadState::self();
210        const int calling_pid = ipc->getCallingPid();
211        const int calling_uid = ipc->getCallingUid();
212        if (!PermissionCache::checkPermission(KEYGUARD_PERMISSION, calling_pid, calling_uid)) {
213            ALOGE("%s: permission denied for [%d:%d]", __func__, calling_pid, calling_uid);
214            return;
215        }
216        clear_sid(uid);
217    }
218
219    virtual status_t dump(int fd, const Vector<String16> &) {
220        IPCThreadState* ipc = IPCThreadState::self();
221        const int pid = ipc->getCallingPid();
222        const int uid = ipc->getCallingUid();
223        if (!PermissionCache::checkPermission(DUMP_PERMISSION, pid, uid)) {
224            return PERMISSION_DENIED;
225        }
226
227        if (device == NULL) {
228            const char *result = "Device not available";
229            write(fd, result, strlen(result) + 1);
230        } else {
231            const char *result = "OK";
232            write(fd, result, strlen(result) + 1);
233        }
234
235        return NO_ERROR;
236    }
237
238private:
239    gatekeeper_device_t *device;
240    UniquePtr<SoftGateKeeperDevice> soft_device;
241    const hw_module_t *module;
242};
243}// namespace android
244
245int main(int argc, char* argv[]) {
246    ALOGI("Starting gatekeeperd...");
247    if (argc < 2) {
248        ALOGE("A directory must be specified!");
249        return 1;
250    }
251    if (chdir(argv[1]) == -1) {
252        ALOGE("chdir: %s: %s", argv[1], strerror(errno));
253        return 1;
254    }
255
256    android::sp<android::IServiceManager> sm = android::defaultServiceManager();
257    android::sp<android::GateKeeperProxy> proxy = new android::GateKeeperProxy();
258    android::status_t ret = sm->addService(
259            android::String16("android.service.gatekeeper.IGateKeeperService"), proxy);
260    if (ret != android::OK) {
261        ALOGE("Couldn't register binder service!");
262        return -1;
263    }
264
265    /*
266     * We're the only thread in existence, so we're just going to process
267     * Binder transaction as a single-threaded program.
268     */
269    android::IPCThreadState::self()->joinThreadPool();
270    return 0;
271}
272