ext4_crypt_init_extensions.cpp revision 883d7a7d08cae35d8a1479c4d5b40d2d8fa3ff5c 
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#include <unistd.h>
12
13#include <cutils/klog.h>
14#include <cutils/properties.h>
15#include <cutils/sockets.h>
16#include <poll.h>
17
18#include "key_control.h"
19#include "unencrypted_properties.h"
20
21static const std::string arbitrary_sequence_number = "42";
22static const int vold_command_timeout_ms = 60 * 1000;
23
24static std::string vold_command(std::string const& command)
25{
26    KLOG_INFO(TAG, "Running command %s\n", command.c_str());
27    int sock = -1;
28
29    while (true) {
30        sock = socket_local_client("cryptd",
31                                   ANDROID_SOCKET_NAMESPACE_RESERVED,
32                                   SOCK_STREAM);
33        if (sock >= 0) {
34            break;
35        }
36        usleep(10000);
37    }
38
39    if (sock < 0) {
40        KLOG_INFO(TAG, "Cannot open vold, failing command (%s)\n", strerror(errno));
41        return "";
42    }
43
44    class CloseSocket
45    {
46        int sock_;
47    public:
48        CloseSocket(int sock) : sock_(sock) {}
49        ~CloseSocket() { close(sock_); }
50    };
51
52    CloseSocket cs(sock);
53
54    // Use arbitrary sequence number. This should only be used when the
55    // framework is down, so this is (mostly) OK.
56    std::string actual_command = arbitrary_sequence_number + " " + command;
57    if (write(sock, actual_command.c_str(), actual_command.size() + 1) < 0) {
58        KLOG_ERROR(TAG, "Cannot write command (%s)\n", strerror(errno));
59        return "";
60    }
61
62    struct pollfd poll_sock = {sock, POLLIN, 0};
63
64    int rc = TEMP_FAILURE_RETRY(poll(&poll_sock, 1, vold_command_timeout_ms));
65    if (rc < 0) {
66        KLOG_ERROR(TAG, "Error in poll (%s)\n", strerror(errno));
67        return "";
68    }
69
70    if (!(poll_sock.revents & POLLIN)) {
71        KLOG_ERROR(TAG, "Timeout\n");
72        return "";
73    }
74    char buffer[4096];
75    memset(buffer, 0, sizeof(buffer));
76    rc = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
77    if (rc <= 0) {
78        if (rc == 0) {
79            KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n");
80        } else {
81            KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno));
82        }
83        return "";
84    }
85
86    // We don't truly know that this is the correct result. However,
87    // since this will only be used when the framework is down,
88    // it should be OK unless someone is running vdc at the same time.
89    // Worst case we force a reboot in the very rare synchronization
90    // error
91    return std::string(buffer, rc);
92}
93
94int e4crypt_create_device_key(const char* dir,
95                              int ensure_dir_exists(const char*))
96{
97    // Already encrypted with password? If so bail
98    std::string temp_folder = std::string() + dir + "/tmp_mnt";
99    DIR* temp_dir = opendir(temp_folder.c_str());
100    if (temp_dir) {
101        closedir(temp_dir);
102        return 0;
103    }
104
105    // Make sure folder exists. Use make_dir to set selinux permissions.
106    if (ensure_dir_exists(UnencryptedProperties::GetPath(dir).c_str())) {
107        KLOG_ERROR(TAG, "Failed to create %s (%s)\n",
108                   UnencryptedProperties::GetPath(dir).c_str(),
109                   strerror(errno));
110        return -1;
111    }
112
113    auto result = vold_command("cryptfs enablefilecrypto");
114    // ext4enc:TODO proper error handling
115    KLOG_INFO(TAG, "enablefilecrypto returned with result %s\n",
116              result.c_str());
117
118    return 0;
119}
120
121int e4crypt_install_keyring()
122{
123    key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
124                                          KEY_SPEC_SESSION_KEYRING);
125
126    if (device_keyring == -1) {
127        KLOG_ERROR(TAG, "Failed to create keyring (%s)\n", strerror(errno));
128        return -1;
129    }
130
131    KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n",
132              device_keyring, getpid());
133
134    return 0;
135}
136
137int e4crypt_set_directory_policy(const char* dir)
138{
139    // Only set policy on first level /data directories
140    // To make this less restrictive, consider using a policy file.
141    // However this is overkill for as long as the policy is simply
142    // to apply a global policy to all /data folders created via makedir
143    if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
144        return 0;
145    }
146
147    // Don't encrypt lost+found - ext4 doesn't like it
148    if (!strcmp(dir, "/data/lost+found")) {
149        return 0;
150    }
151
152    // ext4enc:TODO exclude /data/user with a horrible special case.
153    if (!strcmp(dir, "/data/user")) {
154        return 0;
155    }
156
157    UnencryptedProperties props("/data");
158    std::string policy = props.Get<std::string>(properties::ref);
159    if (policy.empty()) {
160        // ext4enc:TODO why is this OK?
161        return 0;
162    }
163
164    KLOG_INFO(TAG, "Setting policy on %s\n", dir);
165    int result = do_policy_set(dir, policy.c_str(), policy.size());
166    if (result) {
167        KLOG_ERROR(TAG, "Setting %02x%02x%02x%02x policy on %s failed!\n",
168                   policy[0], policy[1], policy[2], policy[3], dir);
169        return -1;
170    }
171
172    return 0;
173}
174
175int e4crypt_set_user_crypto_policies(const char* dir)
176{
177    auto command = std::string() + "cryptfs setusercryptopolicies " + dir;
178    auto result = vold_command(command);
179    // ext4enc:TODO proper error handling
180    KLOG_INFO(TAG, "setusercryptopolicies returned with result %s\n",
181              result.c_str());
182    return 0;
183}
184