ext4_crypt_init_extensions.cpp revision 59ffd6d9c7dd3ddaa036956d89c3e4d416769bf6 
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 <android-base/file.h>
15
16#include <cutils/klog.h>
17#include <cutils/properties.h>
18#include <cutils/sockets.h>
19#include <poll.h>
20
21#include "key_control.h"
22
23static const std::string arbitrary_sequence_number = "42";
24static const int vold_command_timeout_ms = 60 * 1000;
25
26static std::string vold_command(std::string const& command)
27{
28    KLOG_INFO(TAG, "Running command %s\n", command.c_str());
29    int sock = -1;
30
31    while (true) {
32        sock = socket_local_client("cryptd",
33                                   ANDROID_SOCKET_NAMESPACE_RESERVED,
34                                   SOCK_STREAM);
35        if (sock >= 0) {
36            break;
37        }
38        usleep(10000);
39    }
40
41    if (sock < 0) {
42        KLOG_INFO(TAG, "Cannot open vold, failing command (%s)\n", strerror(errno));
43        return "";
44    }
45
46    class CloseSocket
47    {
48        int sock_;
49    public:
50        CloseSocket(int sock) : sock_(sock) {}
51        ~CloseSocket() { close(sock_); }
52    };
53
54    CloseSocket cs(sock);
55
56    // Use arbitrary sequence number. This should only be used when the
57    // framework is down, so this is (mostly) OK.
58    std::string actual_command = arbitrary_sequence_number + " " + command;
59    if (write(sock, actual_command.c_str(), actual_command.size() + 1) < 0) {
60        KLOG_ERROR(TAG, "Cannot write command (%s)\n", strerror(errno));
61        return "";
62    }
63
64    struct pollfd poll_sock = {sock, POLLIN, 0};
65
66    int rc = TEMP_FAILURE_RETRY(poll(&poll_sock, 1, vold_command_timeout_ms));
67    if (rc < 0) {
68        KLOG_ERROR(TAG, "Error in poll (%s)\n", strerror(errno));
69        return "";
70    }
71
72    if (!(poll_sock.revents & POLLIN)) {
73        KLOG_ERROR(TAG, "Timeout\n");
74        return "";
75    }
76    char buffer[4096];
77    memset(buffer, 0, sizeof(buffer));
78    rc = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
79    if (rc <= 0) {
80        if (rc == 0) {
81            KLOG_ERROR(TAG, "Lost connection to Vold - did it crash?\n");
82        } else {
83            KLOG_ERROR(TAG, "Error reading data (%s)\n", strerror(errno));
84        }
85        return "";
86    }
87
88    // We don't truly know that this is the correct result. However,
89    // since this will only be used when the framework is down,
90    // it should be OK unless someone is running vdc at the same time.
91    // Worst case we force a reboot in the very rare synchronization
92    // error
93    return std::string(buffer, rc);
94}
95
96int e4crypt_create_device_key(const char* dir,
97                              int ensure_dir_exists(const char*))
98{
99    // Make sure folder exists. Use make_dir to set selinux permissions.
100    std::string unencrypted_dir = std::string(dir) + "/unencrypted";
101    if (ensure_dir_exists(unencrypted_dir.c_str())) {
102        KLOG_ERROR(TAG, "Failed to create %s (%s)\n",
103                   unencrypted_dir.c_str(),
104                   strerror(errno));
105        return -1;
106    }
107
108    auto result = vold_command("cryptfs enablefilecrypto");
109    // ext4enc:TODO proper error handling
110    KLOG_INFO(TAG, "enablefilecrypto returned with result %s\n",
111              result.c_str());
112
113    return 0;
114}
115
116int e4crypt_install_keyring()
117{
118    key_serial_t device_keyring = add_key("keyring", "e4crypt", 0, 0,
119                                          KEY_SPEC_SESSION_KEYRING);
120
121    if (device_keyring == -1) {
122        KLOG_ERROR(TAG, "Failed to create keyring (%s)\n", strerror(errno));
123        return -1;
124    }
125
126    KLOG_INFO(TAG, "Keyring created wth id %d in process %d\n",
127              device_keyring, getpid());
128
129    return 0;
130}
131
132int e4crypt_do_init_user0()
133{
134    auto result = vold_command("cryptfs init_user0");
135    // ext4enc:TODO proper error handling
136    KLOG_INFO(TAG, "init_user0 returned with result %s\n",
137              result.c_str());
138    return 0;
139}
140
141int e4crypt_set_directory_policy(const char* dir)
142{
143    // Only set policy on first level /data directories
144    // To make this less restrictive, consider using a policy file.
145    // However this is overkill for as long as the policy is simply
146    // to apply a global policy to all /data folders created via makedir
147    if (!dir || strncmp(dir, "/data/", 6) || strchr(dir + 6, '/')) {
148        return 0;
149    }
150
151    // Special case various directories that must not be encrypted,
152    // often because their subdirectories must be encrypted.
153    // This isn't a nice way to do this, see b/26641735
154    std::vector<std::string> directories_to_exclude = {
155        "lost+found", "user", "system_ce", "media", "data", "user_de",
156        // ext4enc:TODO workaround that must be removed b/26673855
157        "misc",
158    };
159    std::string prefix = "/data/";
160    for (auto d: directories_to_exclude) {
161        if ((prefix + d) == dir) {
162            KLOG_INFO(TAG, "Not setting policy on %s\n", dir);
163            return 0;
164        }
165    }
166
167    std::string ref_filename = std::string("/data") + e4crypt_key_ref;
168    std::string policy;
169    if (!android::base::ReadFileToString(ref_filename, &policy)) {
170        KLOG_INFO(TAG, "Not file encrypted so no policy for %s\n", dir);
171        return 0;
172    }
173
174    KLOG_INFO(TAG, "Setting policy on %s\n", dir);
175    int result = do_policy_set(dir, policy.c_str(), policy.size());
176    if (result) {
177        KLOG_ERROR(TAG, "Setting %02x%02x%02x%02x policy on %s failed!\n",
178                   policy[0], policy[1], policy[2], policy[3], dir);
179        return -1;
180    }
181
182    return 0;
183}
184