Add vold commands for setting up per-user encrypted user
directories
Bug: 19704432
Change-Id: I15980eed8e4960ca270cf0f8db4e480a8c2ca832
diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
index d1e22ec..7470ff9 100644
--- a/Ext4Crypt.cpp
+++ b/Ext4Crypt.cpp
@@ -7,17 +7,24 @@
#include <sstream>
#include <errno.h>
+#include <dirent.h>
#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
#include <cutils/properties.h>
#include <openssl/sha.h>
#include "unencrypted_properties.h"
#include "key_control.h"
#include "cryptfs.h"
+#include "ext4_crypt_init_extensions.h"
#define LOG_TAG "Ext4Crypt"
#include "cutils/log.h"
#include <cutils/klog.h>
+#include <base/file.h>
+#include <base/stringprintf.h>
namespace {
// Key length in bits
@@ -69,7 +76,7 @@
}
}
-static std::string e4crypt_install_key(const unsigned char *key_bytes);
+static std::string e4crypt_install_key(const std::string &key);
static int put_crypt_ftr_and_key(const crypt_mnt_ftr& crypt_ftr,
UnencryptedProperties& props)
@@ -242,10 +249,10 @@
return -1;
}
- const unsigned char* master_key
+ const unsigned char* master_key_bytes
= reinterpret_cast<const unsigned char*>(&mki->second.master_key[0]);
- if (cryptfs_set_password(&ftr, password, master_key)) {
+ if (cryptfs_set_password(&ftr, password, master_key_bytes)) {
SLOGE("Failed to set password");
return -1;
}
@@ -307,8 +314,8 @@
return -1;
}
- unsigned char master_key[key_length / 8];
- if (cryptfs_get_master_key (&ftr, password, master_key)){
+ unsigned char master_key_bytes[key_length / 8];
+ if (cryptfs_get_master_key (&ftr, password, master_key_bytes)){
SLOGI("Incorrect password");
ftr.failed_decrypt_count++;
if (put_crypt_ftr_and_key(ftr, key_props)) {
@@ -323,12 +330,12 @@
SLOGW("Failed to reset failed_decrypt_count");
}
}
+ std::string master_key(reinterpret_cast<char*>(master_key_bytes),
+ sizeof(master_key_bytes));
struct timespec now;
clock_gettime(CLOCK_BOOTTIME, &now);
- s_key_store[path] = keys{std::string(reinterpret_cast<char*>(master_key),
- sizeof(master_key)),
- password,
+ s_key_store[path] = keys{master_key, password,
now.tv_sec + password_max_age_seconds};
auto raw_ref = e4crypt_install_key(master_key);
if (raw_ref.empty()) {
@@ -346,7 +353,7 @@
// Install password into global keyring
// Return raw key reference for use in policy
-static std::string e4crypt_install_key(const unsigned char *key_bytes)
+static std::string e4crypt_install_key(const std::string &key)
{
// ext4enc:TODO Currently raw key is required to be of length
// sizeof(ext4_key.raw) == EXT4_MAX_KEY_SIZE, so zero pad to
@@ -357,7 +364,7 @@
memset(ext4_key.raw, 0, sizeof(ext4_key.raw));
static_assert(key_length / 8 <= sizeof(ext4_key.raw),
"Key too long!");
- memcpy(ext4_key.raw, key_bytes, key_length / 8);
+ memcpy(ext4_key.raw, &key[0], key.size());
// Get raw keyref - used to make keyname and to pass to ioctl
auto raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size);
@@ -383,7 +390,7 @@
if (key_id == -1) {
SLOGE("Failed to insert key into keyring with error %s",
strerror(errno));
- return std::string();
+ return "";
}
SLOGI("Added key %d (%s) to keyring %d in process %d",
@@ -485,3 +492,123 @@
return GetPropsOrAltProps(path).GetChild(properties::props)
.Set(fieldname, std::string(value)) ? 0 : -1;
}
+
+// ext4enc:TODO this can't be the only place keys are read from /dev/urandom
+// we should unite those places.
+static std::string e4crypt_get_user_key(
+ const char *mount_path,
+ const char *user_handle,
+ bool create_if_absent)
+{
+ // ext4enc:TODO get the path properly
+ auto key_dir = android::base::StringPrintf("%s/misc/vold/user_keys",
+ mount_path);
+ if (mkdir(key_dir.c_str(), 0700) < 0 && errno != EEXIST) {
+ SLOGE("Unable to create %s (%s)", key_dir.c_str(), strerror(errno));
+ return "";
+ }
+ auto key_path = key_dir + "/" + user_handle;
+ std::string content;
+ if (android::base::ReadFileToString(key_path, &content)) {
+ if (content.size() != key_length/8) {
+ SLOGE("Wrong size key %zu in %s", content.size(), key_path.c_str());
+ return "";
+ }
+ return content;
+ }
+ if (!create_if_absent) {
+ SLOGE("No key found in %s", key_path.c_str());
+ return "";
+ }
+ std::ifstream urandom("/dev/urandom");
+ if (!urandom) {
+ SLOGE("Unable to open /dev/urandom (%s)", strerror(errno));
+ return "";
+ }
+ char key_bytes[key_length / 8];
+ errno = 0;
+ urandom.read(key_bytes, sizeof(key_bytes));
+ if (!urandom) {
+ SLOGE("Unable to read key from /dev/urandom (%s)", strerror(errno));
+ return "";
+ }
+ std::string user_key(key_bytes, sizeof(key_bytes));
+ if (!android::base::WriteStringToFile(user_key, key_path)) {
+ SLOGE("Unable to write key to %s (%s)",
+ key_path.c_str(), strerror(errno));
+ return "";
+ }
+ return user_key;
+}
+
+static int e4crypt_set_user_policy(const char *mount_path, const char *user_handle,
+ const char *path, bool create_if_absent)
+{
+ SLOGD("e4crypt_set_user_policy for %s", user_handle);
+ auto user_key = e4crypt_get_user_key(mount_path, user_handle,
+ create_if_absent);
+ if (user_key.empty()) {
+ return -1;
+ }
+ auto raw_ref = e4crypt_install_key(user_key);
+ if (raw_ref.empty()) {
+ return -1;
+ }
+ return do_policy_set(path, raw_ref.c_str(), raw_ref.size());
+}
+
+int e4crypt_create_new_user_dir(const char *user_handle, const char *path) {
+ SLOGD("e4crypt_create_new_user_dir(\"%s\", \"%s\")", user_handle, path);
+ if (mkdir(path, S_IRWXU | S_IRWXG | S_IXOTH) < 0) {
+ return -1;
+ }
+ if (chmod(path, S_IRWXU | S_IRWXG | S_IXOTH) < 0) {
+ return -1;
+ }
+ if (e4crypt_crypto_complete(DATA_MNT_POINT) == 0) {
+ // ext4enc:TODO handle errors from this.
+ e4crypt_set_user_policy(DATA_MNT_POINT, user_handle, path, true);
+ }
+ return 0;
+}
+
+static bool is_numeric(const char *name) {
+ for (const char *p = name; *p != '\0'; p++) {
+ if (!isdigit(*p))
+ return false;
+ }
+ return true;
+}
+
+int e4crypt_set_user_crypto_policies(const char *dir)
+{
+ if (e4crypt_crypto_complete(DATA_MNT_POINT) != 0) {
+ return 0;
+ }
+ SLOGD("e4crypt_set_user_crypto_policies");
+ std::unique_ptr<DIR, int(*)(DIR*)> dirp(opendir(dir), closedir);
+ if (!dirp) {
+ SLOGE("Unable to read directory %s, error %s\n",
+ dir, strerror(errno));
+ return -1;
+ }
+ for (;;) {
+ struct dirent *result = readdir(dirp.get());
+ if (!result) {
+ // ext4enc:TODO check errno
+ break;
+ }
+ if (result->d_type != DT_DIR || !is_numeric(result->d_name)) {
+ continue; // skips user 0, which is a symlink
+ }
+ auto user_dir = std::string() + dir + "/" + result->d_name;
+ // ext4enc:TODO don't hardcode /data
+ if (e4crypt_set_user_policy("/data", result->d_name,
+ user_dir.c_str(), false)) {
+ // ext4enc:TODO If this function fails, stop the boot: we must
+ // deliver on promised encryption.
+ SLOGE("Unable to set policy on %s\n", user_dir.c_str());
+ }
+ }
+ return 0;
+}