1 files changed, 146 insertions, 0 deletions
diff --git a/libfscrypt/fscrypt_init_extensions.cpp b/libfscrypt/fscrypt_init_extensions.cpp
new file mode 100644
index 00000000..2fd70e79
--- /dev/null
+++ b/libfscrypt/fscrypt_init_extensions.cpp
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "fscrypt/fscrypt.h"
+#include "fscrypt/fscrypt_init_extensions.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+#include <android-base/strings.h>
+#include <cutils/properties.h>
+#include <cutils/sockets.h>
+#include <keyutils.h>
+#include <logwrap/logwrap.h>
+
+#define TAG "fscrypt"
+
+static const std::string arbitrary_sequence_number = "42";
+
+static int set_policy_on(char const* ref_basename, char const* dir);
+
+int fscrypt_install_keyring()
+{
+    key_serial_t device_keyring = add_key("keyring", "fscrypt", 0, 0,
+                                          KEY_SPEC_SESSION_KEYRING);
+
+    if (device_keyring == -1) {
+        PLOG(ERROR) << "Failed to create keyring";
+        return -1;
+    }
+
+    LOG(INFO) << "Keyring created with id " << device_keyring << " in process " << getpid();
+
+    return 0;
+}
+
+int fscrypt_set_directory_policy(const char* dir)
+{
+    if (!dir || strncmp(dir, "/data/", 6)) {
+        return 0;
+    }
+
+    // Special-case /data/media/obb per b/64566063
+    if (strcmp(dir, "/data/media/obb") == 0) {
+        // Try to set policy on this directory, but if it is non-empty this may fail.
+        set_policy_on(fscrypt_key_ref, dir);
+        return 0;
+    }
+
+    // Only set policy on first level /data directories
+    // To make this less restrictive, consider using a policy file.
+    // However this is overkill for as long as the policy is simply
+    // to apply a global policy to all /data folders created via makedir
+    if (strchr(dir + 6, '/')) {
+        return 0;
+    }
+
+    // Special case various directories that must not be encrypted,
+    // often because their subdirectories must be encrypted.
+    // This isn't a nice way to do this, see b/26641735
+    std::vector<std::string> directories_to_exclude = {
+        "lost+found",
+        "system_ce", "system_de",
+        "misc_ce", "misc_de",
+        "vendor_ce", "vendor_de",
+        "media",
+        "data", "user", "user_de",
+        "apex", "preloads", "app-staging",
+        "gsi",
+    };
+    std::string prefix = "/data/";
+    for (const auto& d: directories_to_exclude) {
+        if ((prefix + d) == dir) {
+            LOG(INFO) << "Not setting policy on " << dir;
+            return 0;
+        }
+    }
+    std::vector<std::string> per_boot_directories = {
+        "per_boot",
+    };
+    for (const auto& d : per_boot_directories) {
+        if ((prefix + d) == dir) {
+            LOG(INFO) << "Setting per_boot key on " << dir;
+            return set_policy_on(fscrypt_key_per_boot_ref, dir);
+        }
+    }
+    return set_policy_on(fscrypt_key_ref, dir);
+}
+
+static int set_policy_on(char const* ref_basename, char const* dir) {
+    std::string ref_filename = std::string("/data") + ref_basename;
+    std::string policy;
+    if (!android::base::ReadFileToString(ref_filename, &policy)) {
+        LOG(ERROR) << "Unable to read system policy to set on " << dir;
+        return -1;
+    }
+
+    auto type_filename = std::string("/data") + fscrypt_key_mode;
+    std::string modestring;
+    if (!android::base::ReadFileToString(type_filename, &modestring)) {
+        LOG(ERROR) << "Cannot read mode";
+    }
+
+    std::vector<std::string> modes = android::base::Split(modestring, ":");
+
+    if (modes.size() < 1 || modes.size() > 2) {
+        LOG(ERROR) << "Invalid encryption mode string: " << modestring;
+        return -1;
+    }
+
+    LOG(INFO) << "Setting policy on " << dir;
+    int result = fscrypt_policy_ensure(dir, policy.c_str(), policy.length(),
+                                       modes[0].c_str(),
+                                       modes.size() >= 2 ?
+                                            modes[1].c_str() : "aes-256-cts");
+    if (result) {
+        LOG(ERROR) << android::base::StringPrintf(
+            "Setting %02x%02x%02x%02x policy on %s failed!",
+            policy[0], policy[1], policy[2], policy[3], dir);
+        return -1;
+    }
+
+    return 0;
+}