summaryrefslogtreecommitdiffstats
blob: f0c36294bb07ddd24efd75f7a6ffbd4ad665d1aa (plain) (blame)
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
/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define TRACE_TAG AUTH

#include "adb.h"
#include "adb_auth.h"
#include "fdevent.h"
#include "sysdeps.h"
#include "transport.h"

#include <resolv.h>
#include <stdio.h>
#include <string.h>

#include <memory>

#include <android-base/file.h>
#include <android-base/strings.h>
#include <crypto_utils/android_pubkey.h>
#include <openssl/obj_mac.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>

static fdevent* listener_fde = nullptr;
static fdevent* framework_fde = nullptr;
static int framework_fd = -1;

static void usb_disconnected(void* unused, atransport* t);
static struct adisconnect usb_disconnect = { usb_disconnected, nullptr};
static atransport* usb_transport;
static bool needs_retry = false;

bool auth_required = true;

bool adbd_auth_verify(const char* token, size_t token_size, const std::string& sig) {
    static constexpr const char* key_paths[] = { "/adb_keys", "/data/misc/adb/adb_keys", nullptr };

    for (const auto& path : key_paths) {
        if (access(path, R_OK) == 0) {
            LOG(INFO) << "Loading keys from " << path;

            std::string content;
            if (!android::base::ReadFileToString(path, &content)) {
                PLOG(ERROR) << "Couldn't read " << path;
                continue;
            }

            for (const auto& line : android::base::Split(content, "\n")) {
                // TODO: do we really have to support both ' ' and '\t'?
                char* sep = strpbrk(const_cast<char*>(line.c_str()), " \t");
                if (sep) *sep = '\0';

                // b64_pton requires one additional byte in the target buffer for
                // decoding to succeed. See http://b/28035006 for details.
                uint8_t keybuf[ANDROID_PUBKEY_ENCODED_SIZE + 1];
                if (__b64_pton(line.c_str(), keybuf, sizeof(keybuf)) != ANDROID_PUBKEY_ENCODED_SIZE) {
                    LOG(ERROR) << "Invalid base64 key " << line.c_str() << " in " << path;
                    continue;
                }

                RSA* key = nullptr;
                if (!android_pubkey_decode(keybuf, ANDROID_PUBKEY_ENCODED_SIZE, &key)) {
                    LOG(ERROR) << "Failed to parse key " << line.c_str() << " in " << path;
                    continue;
                }

                bool verified =
                    (RSA_verify(NID_sha1, reinterpret_cast<const uint8_t*>(token), token_size,
                                reinterpret_cast<const uint8_t*>(sig.c_str()), sig.size(),
                                key) == 1);
                RSA_free(key);
                if (verified) return true;
            }
        }
    }
    return false;
}

static bool adbd_auth_generate_token(void* token, size_t token_size) {
    FILE* fp = fopen("/dev/urandom", "re");
    if (!fp) return false;
    bool okay = (fread(token, token_size, 1, fp) == 1);
    fclose(fp);
    return okay;
}

static void usb_disconnected(void* unused, atransport* t) {
    LOG(INFO) << "USB disconnect";
    usb_transport = NULL;
    needs_retry = false;
}

static void framework_disconnected() {
    LOG(INFO) << "Framework disconnect";
    if (framework_fde) {
        fdevent_destroy(framework_fde);
        framework_fd = -1;
    }
}

static void adbd_auth_event(int fd, unsigned events, void*) {
    if (events & FDE_READ) {
        char response[2];
        int ret = unix_read(fd, response, sizeof(response));
        if (ret <= 0) {
            framework_disconnected();
        } else if (ret == 2 && response[0] == 'O' && response[1] == 'K') {
            if (usb_transport) {
                adbd_auth_verified(usb_transport);
            }
        }
    }
}

void adbd_auth_confirm_key(const char* key, size_t len, atransport* t) {
    if (!usb_transport) {
        usb_transport = t;
        t->AddDisconnect(&usb_disconnect);
    }

    if (framework_fd < 0) {
        LOG(ERROR) << "Client not connected";
        needs_retry = true;
        return;
    }

    if (key[len - 1] != '\0') {
        LOG(ERROR) << "Key must be a null-terminated string";
        return;
    }

    char msg[MAX_PAYLOAD_V1];
    int msg_len = snprintf(msg, sizeof(msg), "PK%s", key);
    if (msg_len >= static_cast<int>(sizeof(msg))) {
        LOG(ERROR) << "Key too long (" << msg_len << ")";
        return;
    }
    LOG(DEBUG) << "Sending '" << msg << "'";

    if (unix_write(framework_fd, msg, msg_len) == -1) {
        PLOG(ERROR) << "Failed to write PK";
        return;
    }
}

static void adbd_auth_listener(int fd, unsigned events, void* data) {
    int s = adb_socket_accept(fd, nullptr, nullptr);
    if (s < 0) {
        PLOG(ERROR) << "Failed to accept";
        return;
    }

    if (framework_fd >= 0) {
        LOG(WARNING) << "adb received framework auth socket connection again";
        framework_disconnected();
    }

    framework_fd = s;
    framework_fde = fdevent_create(framework_fd, adbd_auth_event, nullptr);
    fdevent_add(framework_fde, FDE_READ);

    if (needs_retry) {
        needs_retry = false;
        send_auth_request(usb_transport);
    }
}

void adbd_cloexec_auth_socket() {
    int fd = android_get_control_socket("adbd");
    if (fd == -1) {
        PLOG(ERROR) << "Failed to get adbd socket";
        return;
    }
    fcntl(fd, F_SETFD, FD_CLOEXEC);
}

void adbd_auth_init(void) {
    int fd = android_get_control_socket("adbd");
    if (fd == -1) {
        PLOG(ERROR) << "Failed to get adbd socket";
        return;
    }

    if (listen(fd, 4) == -1) {
        PLOG(ERROR) << "Failed to listen on '" << fd << "'";
        return;
    }

    listener_fde = fdevent_create(fd, adbd_auth_listener, NULL);
    fdevent_add(listener_fde, FDE_READ);
}

void send_auth_request(atransport* t) {
    LOG(INFO) << "Calling send_auth_request...";

    if (!adbd_auth_generate_token(t->token, sizeof(t->token))) {
        PLOG(ERROR) << "Error generating token";
        return;
    }

    apacket* p = get_apacket();
    p->msg.command = A_AUTH;
    p->msg.arg0 = ADB_AUTH_TOKEN;
    p->msg.data_length = sizeof(t->token);
    p->payload.assign(t->token, t->token + sizeof(t->token));
    send_packet(p, t);
}

void adbd_auth_verified(atransport* t) {
    LOG(INFO) << "adb client authorized";
    handle_online(t);
    send_connect(t);
}