ext4_crypt_init_extensions.cpp revision e0b351bc2ccdd92068ba269c5346256f0b3ec49e 
1#define TAG "ext4_utils"
2
3#include "ext4_crypt_init_extensions.h"
4
5#include <string>
6#include <vector>
7
8#include <dirent.h>
9#include <errno.h>
10#include <sys/mount.h>
11#include <sys/stat.h>
12#include <unistd.h>
13
14#include <cutils/klog.h>
15#include <cutils/properties.h>
16#include <cutils/sockets.h>
17#include <poll.h>
18
19#include "key_control.h"
20#include "unencrypted_properties.h"
21
22static const std::string arbitrary_sequence_number = "42";
23static const int vold_command_timeout_ms = 60 * 1000;
24
25static std::string vold_command(std::string const& command)
26{
27    KLOG_INFO(TAG, "Running command %s\n", command.c_str());
28    int sock = -1;
29
30    while (true) {
31        sock = socket_local_client("cryptd",
32                                   ANDROID_SOCKET_NAMESPACE_RESERVED,
33                                   SOCK_STREAM);
34        if (sock >= 0) {
35            break;
36        }
37        usleep(10000);
38    }
39
40    if (sock < 0) {
41        KLOG_INFO(TAG, "Cannot open vold, failing command (%s)\n", strerror(errno));
42        return "";
43    }
44
45    class CloseSocket
46    {
47        int sock_;
48    public:
49        CloseSocket(int sock) : sock_(sock) {}
50        ~CloseSocket() { close(sock_); }
51    };
52
53    CloseSocket cs(sock);
54
55    // Use arbitrary sequence number. This should only be used when the
56    // framework is down, so this is (mostly) OK.
57    std::string actual_command = arbitrary_sequence_number + " " + command;
58    if (write(sock, actual_command.c_str(), actual_command.size() + 1) < 0) {
59        KLOG_ERROR(TAG, "Cannot write command (%s)\n", strerror(errno));
60        return "";
61    }
62
63    struct pollfd poll_sock = {sock, POLLIN, 0};
64
65    int rc = TEMP_FAILURE_RETRY(poll(&poll_sock, 1, vold_command_timeout_ms));
66    if (rc < 0) {
67        KLOG_ERROR(TAG, "Error in poll (%s)\n", strerror(errno));
68        return "";
69    }
70
71    if (!(poll_sock.revents & POLLIN)) {
72        KLOG_ERROR(TAG, "Timeout\n");
73        return "";
74    }
75    char buffer[4096];
76    memset(buffer, 0, sizeof(buffer));
77    rc = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
78    if (rc <= 0) {
79        if (rc == 0) {
80            KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n");
81        } else {
82            KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno));
83        }
84        return "";
85    }
86
87    // We don't truly know that this is the correct result. However,
88    // since this will only be used when the framework is down,
89    // it should be OK unless someone is running vdc at the same time.
90    // Worst case we force a reboot in the very rare synchronization
91    // error
92    return std::string(buffer, rc);
93}
94
95int e4crypt_create_device_key(const char* dir,
96                              int ensure_dir_exists(const char*))
97{
98    // Already encrypted with password? If so bail
99    std::string temp_folder = std::string() + dir + "/tmp_mnt";
100    DIR* temp_dir = opendir(temp_folder.c_str());
101    if (temp_dir) {
102        closedir(temp_dir);
103        return 0;
104    }
105
106    // Make sure folder exists. Use make_dir to set selinux permissions.
107    if (ensure_dir_exists(UnencryptedProperties::GetPath(dir).c_str())) {
108        KLOG_ERROR(TAG, "Failed to create %s (%s)\n",
109                   UnencryptedProperties::GetPath(dir).c_str(),
110                   strerror(errno));
111        return -1;
112    }
113
114    auto result = vold_command("cryptfs enablefilecrypto");
115    // ext4enc:TODO proper error handling
116    KLOG_INFO(TAG, "enablefilecrypto returned with result %s\n",
117              result.c_str());
118
119    return 0;
120}
121
122int e4crypt_install_keyring()
123{
124    key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
125                                          KEY_SPEC_SESSION_KEYRING);
126
127    if (device_keyring == -1) {
128        KLOG_ERROR(TAG, "Failed to create keyring (%s)\n", strerror(errno));
129        return -1;
130    }
131
132    KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n",
133              device_keyring, getpid());
134
135    return 0;
136}
137
138int e4crypt_set_directory_policy(const char* dir)
139{
140    // Only set policy on first level /data directories
141    // To make this less restrictive, consider using a policy file.
142    // However this is overkill for as long as the policy is simply
143    // to apply a global policy to all /data folders created via makedir
144    if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
145        return 0;
146    }
147
148    // Special case various directories that must not be encrypted,
149    // often because their subdirectories must be encrypted.
150    // This isn't a nice way to do this, see b/26641735
151    std::vector<std::string> directories_to_exclude = {
152        "lost+found", "user", "system_ce", "media", "data", "user_de",
153        // ext4enc:TODO workaround that must be removed b/26673855
154        "misc",
155    };
156    std::string prefix = "/data/";
157    for (auto d: directories_to_exclude) {
158        if ((prefix + d) == dir) {
159            KLOG_INFO(TAG, "Not setting policy on %s\n", dir);
160            return 0;
161        }
162    }
163    UnencryptedProperties props("/data");
164    std::string policy = props.Get<std::string>(properties::ref);
165    if (policy.empty()) {
166        // ext4enc:TODO why is this OK?
167        return 0;
168    }
169
170    KLOG_INFO(TAG, "Setting policy on %s\n", dir);
171    int result = do_policy_set(dir, policy.c_str(), policy.size());
172    if (result) {
173        KLOG_ERROR(TAG, "Setting %02x%02x%02x%02x policy on %s failed!\n",
174                   policy[0], policy[1], policy[2], policy[3], dir);
175        return -1;
176    }
177
178    return 0;
179}
180