ext4_crypt_init_extensions.cpp revision 0050336a0a19019a68374b9eef51e00d6b242f57 
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("vold",
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\n");
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\n");
58        return "";
59    }
60
61    struct pollfd poll_sock = {sock, POLLIN, 0};
62
63    int rc = 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    if (!(poll_sock.revents & POLLIN)) {
69        KLOG_ERROR(TAG, "Timeout\n");
70        return "";
71    }
72    char buffer[4096];
73    memset(buffer, 0, sizeof(buffer));
74    rc = read(sock, buffer, sizeof(buffer));
75    if (rc <= 0) {
76        if (rc == 0) {
77            KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n");
78        } else {
79            KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno));
80        }
81        return "";
82    }
83
84    // We don't truly know that this is the correct result. However,
85    // since this will only be used when the framework is down,
86    // it should be OK unless someone is running vdc at the same time.
87    // Worst case we force a reboot in the very rare synchronization
88    // error
89    return std::string(buffer, rc);
90}
91
92int e4crypt_create_device_key(const char* dir,
93                              int ensure_dir_exists(const char*))
94{
95    // Already encrypted with password? If so bail
96    std::string temp_folder = std::string() + dir + "/tmp_mnt";
97    DIR* temp_dir = opendir(temp_folder.c_str());
98    if (temp_dir) {
99        closedir(temp_dir);
100        return 0;
101    }
102
103    // Make sure folder exists. Use make_dir to set selinux permissions.
104    if (ensure_dir_exists(UnencryptedProperties::GetPath(dir).c_str())) {
105        KLOG_ERROR(TAG, "Failed to create %s with error %s\n",
106                   UnencryptedProperties::GetPath(dir).c_str(),
107                   strerror(errno));
108        return -1;
109    }
110
111    auto result = vold_command("cryptfs enablefilecrypto");
112    // ext4enc:TODO proper error handling
113    KLOG_INFO(TAG, "enablefilecrypto returned with result %s\n",
114              result.c_str());
115
116    return 0;
117}
118
119int e4crypt_install_keyring()
120{
121    key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
122                                          KEY_SPEC_SESSION_KEYRING);
123
124    if (device_keyring == -1) {
125        KLOG_ERROR(TAG, "Failed to create keyring\n");
126        return -1;
127    }
128
129    KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n",
130              device_keyring, getpid());
131
132    return 0;
133}
134
135int e4crypt_set_directory_policy(const char* dir)
136{
137    // Only set policy on first level /data directories
138    // To make this less restrictive, consider using a policy file.
139    // However this is overkill for as long as the policy is simply
140    // to apply a global policy to all /data folders created via makedir
141    if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
142        return 0;
143    }
144    // ext4enc:TODO exclude /data/user with a horrible special case.
145    if (!strcmp(dir, "/data/user")) {
146        return 0;
147    }
148
149    UnencryptedProperties props("/data");
150    std::string policy = props.Get<std::string>(properties::ref);
151    if (policy.empty()) {
152        // ext4enc:TODO why is this OK?
153        return 0;
154    }
155
156    KLOG_INFO(TAG, "Setting policy on %s\n", dir);
157    int result = do_policy_set(dir, policy.c_str(), policy.size());
158    if (result) {
159        KLOG_ERROR(TAG, "Setting %s policy on %s failed!\n",
160                   policy.c_str(), dir);
161        return -1;
162    }
163
164    return 0;
165}
166