1#define TAG "ext4_utils"
2
3#include "ext4_crypt_init_extensions.h"
4
5#include <string>
6
7#include <dirent.h>
8#include <errno.h>
9#include <sys/mount.h>
10#include <sys/stat.h>
11
12#include <cutils/klog.h>
13#include <cutils/properties.h>
14#include <cutils/sockets.h>
15#include <poll.h>
16
17#include "key_control.h"
18#include "unencrypted_properties.h"
19
20static const std::string arbitrary_sequence_number = "42";
21static const int vold_command_timeout_ms = 60 * 1000;
22
23static std::string vold_command(std::string const& command)
24{
25    KLOG_INFO(TAG, "Running command %s\n", command.c_str());
26    int sock = -1;
27
28    while (true) {
29        sock = socket_local_client("cryptd",
30                                   ANDROID_SOCKET_NAMESPACE_RESERVED,
31                                   SOCK_STREAM);
32        if (sock >= 0) {
33            break;
34        }
35        usleep(10000);
36    }
37
38    if (sock < 0) {
39        KLOG_INFO(TAG, "Cannot open vold, failing command (%s)\n", strerror(errno));
40        return "";
41    }
42
43    class CloseSocket
44    {
45        int sock_;
46    public:
47        CloseSocket(int sock) : sock_(sock) {}
48        ~CloseSocket() { close(sock_); }
49    };
50
51    CloseSocket cs(sock);
52
53    // Use arbitrary sequence number. This should only be used when the
54    // framework is down, so this is (mostly) OK.
55    std::string actual_command = arbitrary_sequence_number + " " + command;
56    if (write(sock, actual_command.c_str(), actual_command.size() + 1) < 0) {
57        KLOG_ERROR(TAG, "Cannot write command (%s)\n", strerror(errno));
58        return "";
59    }
60
61    struct pollfd poll_sock = {sock, POLLIN, 0};
62
63    int rc = TEMP_FAILURE_RETRY(poll(&poll_sock, 1, vold_command_timeout_ms));
64    if (rc < 0) {
65        KLOG_ERROR(TAG, "Error in poll (%s)\n", strerror(errno));
66        return "";
67    }
68
69    if (!(poll_sock.revents & POLLIN)) {
70        KLOG_ERROR(TAG, "Timeout\n");
71        return "";
72    }
73    char buffer[4096];
74    memset(buffer, 0, sizeof(buffer));
75    rc = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
76    if (rc <= 0) {
77        if (rc == 0) {
78            KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n");
79        } else {
80            KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno));
81        }
82        return "";
83    }
84
85    // We don't truly know that this is the correct result. However,
86    // since this will only be used when the framework is down,
87    // it should be OK unless someone is running vdc at the same time.
88    // Worst case we force a reboot in the very rare synchronization
89    // error
90    return std::string(buffer, rc);
91}
92
93int e4crypt_create_device_key(const char* dir,
94                              int ensure_dir_exists(const char*))
95{
96    // Already encrypted with password? If so bail
97    std::string temp_folder = std::string() + dir + "/tmp_mnt";
98    DIR* temp_dir = opendir(temp_folder.c_str());
99    if (temp_dir) {
100        closedir(temp_dir);
101        return 0;
102    }
103
104    // Make sure folder exists. Use make_dir to set selinux permissions.
105    if (ensure_dir_exists(UnencryptedProperties::GetPath(dir).c_str())) {
106        KLOG_ERROR(TAG, "Failed to create %s (%s)\n",
107                   UnencryptedProperties::GetPath(dir).c_str(),
108                   strerror(errno));
109        return -1;
110    }
111
112    auto result = vold_command("cryptfs enablefilecrypto");
113    // ext4enc:TODO proper error handling
114    KLOG_INFO(TAG, "enablefilecrypto returned with result %s\n",
115              result.c_str());
116
117    return 0;
118}
119
120int e4crypt_install_keyring()
121{
122    key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
123                                          KEY_SPEC_SESSION_KEYRING);
124
125    if (device_keyring == -1) {
126        KLOG_ERROR(TAG, "Failed to create keyring (%s)\n", strerror(errno));
127        return -1;
128    }
129
130    KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n",
131              device_keyring, getpid());
132
133    return 0;
134}
135
136int e4crypt_set_directory_policy(const char* dir)
137{
138    // Only set policy on first level /data directories
139    // To make this less restrictive, consider using a policy file.
140    // However this is overkill for as long as the policy is simply
141    // to apply a global policy to all /data folders created via makedir
142    if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
143        return 0;
144    }
145
146    // Don't encrypt lost+found - ext4 doesn't like it
147    if (!strcmp(dir, "/data/lost+found")) {
148        return 0;
149    }
150
151    // ext4enc:TODO exclude /data/user with a horrible special case.
152    if (!strcmp(dir, "/data/user")) {
153        return 0;
154    }
155
156    UnencryptedProperties props("/data");
157    std::string policy = props.Get<std::string>(properties::ref);
158    if (policy.empty()) {
159        // ext4enc:TODO why is this OK?
160        return 0;
161    }
162
163    KLOG_INFO(TAG, "Setting policy on %s\n", dir);
164    int result = do_policy_set(dir, policy.c_str(), policy.size());
165    if (result) {
166        KLOG_ERROR(TAG, "Setting %02x%02x%02x%02x policy on %s failed!\n",
167                   policy[0], policy[1], policy[2], policy[3], dir);
168        return -1;
169    }
170
171    return 0;
172}
173
174int e4crypt_set_user_crypto_policies(const char* dir)
175{
176    auto command = std::string() + "cryptfs setusercryptopolicies " + dir;
177    auto result = vold_command(command);
178    // ext4enc:TODO proper error handling
179    KLOG_INFO(TAG, "setusercryptopolicies returned with result %s\n",
180              result.c_str());
181    return 0;
182}
183