1 files changed, 83 insertions, 0 deletions
diff --git a/libkeyutils/mini_keyctl/mini_keyctl_utils.cpp b/libkeyutils/mini_keyctl/mini_keyctl_utils.cpp
new file mode 100644
index 000000000..fb9503f14
--- /dev/null
+++ b/libkeyutils/mini_keyctl/mini_keyctl_utils.cpp
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2019 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 <mini_keyctl_utils.h>
+
+#include <fstream>
+#include <iterator>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+
+namespace android {
+
+namespace {
+
+std::vector<std::string> SplitBySpace(const std::string& s) {
+  std::istringstream iss(s);
+  return std::vector<std::string>{std::istream_iterator<std::string>{iss},
+                                  std::istream_iterator<std::string>{}};
+}
+
+}  // namespace
+
+// Find the keyring id. request_key(2) only finds keys in the process, session or thread keyring
+// hierarchy, but not internal keyring of a kernel subsystem (e.g. .fs-verity). To support all
+// cases, this function looks up a keyring's ID by parsing /proc/keys. The keyring description may
+// contain other information in the descritption section depending on the key type, only the first
+// word in the keyring description is used for searching.
+key_serial_t GetKeyringId(const std::string& keyring_desc) {
+  // If the keyring id is already a hex number, directly convert it to keyring id
+  key_serial_t keyring_id;
+  if (android::base::ParseInt(keyring_desc.c_str(), &keyring_id)) {
+    return keyring_id;
+  }
+
+  // Only keys allowed by SELinux rules will be shown here.
+  std::ifstream proc_keys_file("/proc/keys");
+  if (!proc_keys_file.is_open()) {
+    PLOG(ERROR) << "Failed to open /proc/keys";
+    return -1;
+  }
+
+  std::string line;
+  while (getline(proc_keys_file, line)) {
+    std::vector<std::string> tokens = SplitBySpace(line);
+    if (tokens.size() < 9) {
+      continue;
+    }
+    std::string key_id = "0x" + tokens[0];
+    std::string key_type = tokens[7];
+    // The key description may contain space.
+    std::string key_desc_prefix = tokens[8];
+    // The prefix has a ":" at the end
+    std::string key_desc_pattern = keyring_desc + ":";
+    if (key_type != "keyring" || key_desc_prefix != key_desc_pattern) {
+      continue;
+    }
+    if (!android::base::ParseInt(key_id.c_str(), &keyring_id)) {
+      LOG(ERROR) << "Unexpected key format in /proc/keys: " << key_id;
+      return -1;
+    }
+    return keyring_id;
+  }
+  return -1;
+}
+
+}  // namespace android