Initial patch from Will.

src/platform/cryptohome/mount.cc

Index: src/platform/cryptohome/mount.cc
diff --git a/src/platform/cryptohome/mount.cc b/src/platform/cryptohome/mount.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c1eabefcddb1284e5d9683295a7c5f8ad07e27cb
--- /dev/null
+++ b/src/platform/cryptohome/mount.cc
@@ -0,0 +1,998 @@
+// Copyright (c) 2009-2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Contains the implementation of class Mount
+
+// TODO(fes): Use correct ordering of file includes once the platform-specific
+// calls are moved into a separate file.  Right now, this is required in order
+// to avoid redefinitions.
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/platform_thread.h"
+#include "base/time.h"
+#include "base/string_util.h"
+#include "chromeos/utility.h"
+#include "cryptohome/cryptohome_common.h"
+#include "cryptohome/mount.h"
+#include "cryptohome/username_passkey.h"
+
+extern "C" {
+#include <ecryptfs.h>
+#include <keyutils.h>
+}
+#include <dirent.h>
+#include <errno.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/rand.h>
+#include <openssl/sha.h>
+#include <pwd.h>
+#include <signal.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+using std::string;
+
+namespace cryptohome {
+
+const string kDefaultEntropySource = "/dev/urandom";
+const string kDefaultHomeDir = "/home/chronos/user";
+const int kDefaultMountOptions = MS_NOEXEC | MS_NOSUID | MS_NODEV;
+const string kDefaultShadowRoot = "/home/.shadow";
+const string kDefaultSharedUser = "chronos";
+const string kDefaultSkeletonSource = "/etc/skel";
+const string kIncognitoUser = "incognito";
+const string kMtab = "/etc/mtab";
+const string kOpenSSLMagic = "Salted__";
+const std::string kProcDir = "/proc";
+
+Mount::Mount()
+    : default_user_(-1),
+      default_group_(-1),
+      default_username_(kDefaultSharedUser),
+      entropy_source_(kDefaultEntropySource),
+      home_dir_(kDefaultHomeDir),
+      shadow_root_(kDefaultShadowRoot),
+      skel_source_(kDefaultSkeletonSource),
+      system_salt_(),
+      set_vault_ownership_(true) {
+}
+
+Mount::Mount(const std::string& username, const std::string& entropy_source,
+        const std::string& home_dir, const std::string& shadow_root,
+        const std::string& skel_source)
+    : default_user_(-1),
+      default_group_(-1),
+      default_username_(username),
+      entropy_source_(entropy_source),
+      home_dir_(home_dir),
+      shadow_root_(shadow_root),
+      skel_source_(skel_source),
+      system_salt_(),
+      set_vault_ownership_(true) {
+}
+
+Mount::~Mount() {
+}
+
+bool Mount::Init() {
+  bool result = true;
+
+  // Load the passwd entry for the shared user
+  struct passwd* user_info = getpwnam(default_username_.c_str());

[mschilder, 2010/05/27 04:20:18]

getpwnam_r() instead?

+  if (user_info) {
+    // Store the user's uid/gid for later use in changing vault ownership
+    default_user_ = user_info->pw_uid;
+    default_group_ = user_info->pw_gid;
+  } else {
+    result = false;
+  }
+
+  // One-time load of the global system salt (used in generating username
+  // hashes)
+  if (!LoadFileBytes(FilePath(StringPrintf("%s/salt", shadow_root_.c_str())),
+                       system_salt_)) {
+    result = false;
+  }
+
+  return result;
+}
+
+bool Mount::EnsureCryptohome(const Credentials& credentials, bool* created) {
+  // If the user has an old-style cryptohome, delete it
+  FilePath old_image_path(StringPrintf("%s/image",
+                                       GetUserDirectory(credentials).c_str()));
+  if (file_util::PathExists(old_image_path)) {
+    file_util::Delete(FilePath(GetUserDirectory(credentials)), true);
+  }
+  // Now check for the presence of a vault directory
+  FilePath vault_path(GetUserVaultPath(credentials));
+  if (!file_util::DirectoryExists(vault_path)) {
+    // If the vault directory doesn't exist, then create the cryptohome from
+    // scratch
+    bool result = CreateCryptohome(credentials, 0);
+    if (created) {
+      *created = result;
+    }
+    return result;
+  }
+  if (created) {
+    *created = false;
+  }
+  return true;
+}
+
+bool Mount::MountCryptohome(const Credentials& credentials, int index,
+                            MountError* mount_error) {
+  std::string username = credentials.GetFullUsername();
+  if (username.compare(kIncognitoUser) == 0) {
+    // TODO(fes): Have incognito set error conditions?
+    if (mount_error) {
+      *mount_error = MOUNT_ERROR_NONE;
+    }
+    return MountIncognitoCryptohome();
+  }
+
+  bool created = false;
+  if (!EnsureCryptohome(credentials, &created)) {
+    LOG(ERROR) << "Error creating cryptohome.";
+    if (mount_error) {
+      *mount_error = MOUNT_ERROR_FATAL;
+    }
+    return false;
+  }
+
+  FilePath user_key_file(GetUserKeyFile(credentials, index));
+
+  // Retrieve the user's salt for the key index
+  SecureBlob user_salt = GetUserSalt(credentials, index);
+
+  // Generate the passkey wrapper (key encryption key)
+  SecureBlob passkey_wrapper =
+      PasskeyToWrapper(credentials.GetPasskey(), user_salt, 1);
+
+  // Attempt to unwrap the master key at the index with the passkey wrapper
+  VaultKeyset vault_keyset;
+  bool mount_result = UnwrapMasterKey(user_key_file, passkey_wrapper,
+                                      &vault_keyset);
+
+  if (!mount_result) {
+    if (mount_error) {
+      *mount_error = Mount::MOUNT_ERROR_KEY_FAILURE;
+    }
+    return false;
+  }
+
+  // Add the decrypted key to the keyring so that ecryptfs can use it
+  string key_signature, fnek_signature;
+  if (!AddKeyToEcryptfsKeyring(vault_keyset, &key_signature, &fnek_signature)) {
+    LOG(ERROR) << "Cryptohome mount failed because of keyring failure.";
+    if (mount_error) {
+      *mount_error = MOUNT_ERROR_FATAL;
+    }
+    return false;
+  }
+
+  // Specify the ecryptfs options for mounting the user's cryptohome
+  string ecryptfs_options = StringPrintf("ecryptfs_cipher=aes"
+                                         ",ecryptfs_key_bytes=%d"
+                                         ",ecryptfs_fnek_sig=%s,ecryptfs_sig=%s"
+                                         ",ecryptfs_unlink_sigs",
+                                         CRYPTOHOME_AES_KEY_BYTES,
+                                         fnek_signature.c_str(),
+                                         key_signature.c_str());
+
+  // TODO(fes): mount(1) -> mount(2): how to issue "user"
+  string vault_path = GetUserVaultPath(credentials);
+  // Attempt to mount the user's cryptohome
+  if (mount(vault_path.c_str(), home_dir_.c_str(),
+            "ecryptfs", kDefaultMountOptions, ecryptfs_options.c_str())) {
+    LOG(ERROR) << "Cryptohome mount failed: " << errno << " for vault: "
+               << vault_path;
+    if (mount_error) {
+      *mount_error = MOUNT_ERROR_FATAL;
+    }
+    return false;
+  }
+
+  if (created) {
+    CopySkeletonForUser(credentials);
+  }
+
+  if (mount_error) {
+    *mount_error = MOUNT_ERROR_NONE;
+  }
+  return true;
+}
+
+bool Mount::UnmountCryptohome() {
+  // Try an immediate unmount
+  bool was_busy;
+  if (!Unmount(home_dir_.c_str(), false, &was_busy)) {
+    // If the unmount fails, do a lazy unmount
+    Unmount(home_dir_.c_str(), true, NULL);
+    if (was_busy) {
+      // Signal processes to close
+      if (TerminatePidsWithOpenFiles(home_dir_, false)) {
+        // Then we had to send a SIGINT to some processes with open files.  Give
+        // a "grace" period before killing with a SIGKILL.
+        // TODO(fes): This isn't ideal, nor is it accurate (a static sleep can't
+        // guarantee that processes will clean up in time).  If we switch to VFS
+        // namespace-based mounts, then we can get away from this construct.
+        PlatformThread::Sleep(100);
+        sync();
+        if (TerminatePidsWithOpenFiles(home_dir_, true)) {
+          PlatformThread::Sleep(100);
+        }
+      }
+    }
+    sync();
+    // TODO(fes): This should return an error condition if it is still mounted.
+    // Right now it doesn't, since it should get cleaned up outside of
+    // cryptohome since we failed over to a lazy unmount
+  }
+
+  // TODO(fes): Do we need to keep this behavior?
+  //TerminatePidsForUser(default_user_, true);
+
+  // Clear the user keyring if the unmount was successful
+  keyctl(KEYCTL_CLEAR, KEY_SPEC_USER_KEYRING);
+
+  return true;
+}
+
+bool Mount::RemoveCryptohome(const Credentials& credentials) {
+  std::string user_dir = GetUserDirectory(credentials);
+  CHECK(user_dir.length() > (shadow_root_.length() + 1));
+
+  return file_util::Delete(FilePath(user_dir), true);
+}
+
+bool Mount::IsCryptohomeMounted() {
+  // Trivial string match from /etc/mtab to see if the cryptohome mount point is
+  // listed.  This works because Chrome OS is a controlled environment and the
+  // only way /home/chronos/user should be mounted is if cryptohome mounted it.
+  string contents;
+  if (file_util::ReadFileToString(FilePath(kMtab), &contents)) {
+    if (contents.find(StringPrintf(" %s ", home_dir_.c_str()).c_str())
+        != string::npos) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Mount::IsCryptohomeMountedForUser(const Credentials& credentials) {
+  // Trivial string match from /etc/mtab to see if the cryptohome mount point
+  // and the user's vault path are present.  Assumes this user is mounted if it
+  // finds both.  This will need to change if simultaneous login is implemented.
+  string contents;
+  if (file_util::ReadFileToString(FilePath(kMtab), &contents)) {
+    FilePath vault_path(GetUserVaultPath(credentials));
+    if ((contents.find(StringPrintf(" %s ", home_dir_.c_str()).c_str())
+         != string::npos)
+        && (contents.find(StringPrintf("%s ",
+                                       vault_path.value().c_str()).c_str())
+            != string::npos)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Mount::CreateCryptohome(const Credentials& credentials, int index) {
+  // Save the current umask
+  mode_t original_mask = umask(S_IRGRP | S_IWGRP | S_IXGRP | S_IROTH | S_IWOTH
+                               | S_IXOTH);
+
+  // Create the user's entry in the shadow root
+  FilePath user_dir(GetUserDirectory(credentials));
+  file_util::CreateDirectory(user_dir);
+
+  // Generates a new master key and salt at the given index
+  if (!CreateMasterKey(credentials, index)) {
+    umask(original_mask);
+    return false;
+  }
+
+  // Create the user's path and set the proper ownership
+  FilePath vault_path(GetUserVaultPath(credentials));
+  if (!file_util::CreateDirectory(vault_path)) {
+    LOG(ERROR) << "Couldn't create vault path: " << vault_path.value().c_str();
+    umask(original_mask);
+    return false;
+  }
+  if (set_vault_ownership_) {
+    // TODO(fes): Move platform-specific calls to a separate class
+    if (chown(vault_path.value().c_str(), default_user_, default_group_)) {
+      LOG(ERROR) << "Couldn't change owner (" << default_user_ << ":"
+                 << default_group_ << ") of vault path: "
+                 << vault_path.value().c_str();
+      umask(original_mask);
+      return false;
+    }
+  }
+
+  // Restore the umask
+  umask(original_mask);
+  return true;
+}
+
+bool Mount::TestCredentials(const Credentials& credentials) {
+  // Iterate over the keys in the user's entry in the shadow root to see if
+  // these credentials successfully decrypt any
+  for (int index = 0; /* loop forever */; index++) {
+    FilePath user_key_file(GetUserKeyFile(credentials, index));
+    if (!file_util::AbsolutePath(&user_key_file)) {
+      break;
+    }
+
+    SecureBlob user_salt = GetUserSalt(credentials, index);
+
+    SecureBlob passkey_wrapper = PasskeyToWrapper(credentials.GetPasskey(),
+                                                  user_salt, 1);
+
+    VaultKeyset vault_keyset;
+    if (UnwrapMasterKey(user_key_file, passkey_wrapper, &vault_keyset)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool Mount::MigratePasskey(const Credentials& credentials,
+                           const char* old_key) {
+  // Iterate over the keys in the user's entry in the shadow root to see if
+  // these credentials successfully decrypt any
+  std::string username = credentials.GetFullUsername();
+  UsernamePasskey old_credentials(username.c_str(), username.length(),
+                                  old_key, strlen(old_key));
+  for (int index = 0; /* loop forever */; index++) {
+    FilePath user_key_file(GetUserKeyFile(old_credentials, index));
+    if (!file_util::AbsolutePath(&user_key_file)) {
+      break;
+    }
+
+    SecureBlob user_salt = GetUserSalt(old_credentials, index);
+
+    SecureBlob passkey_wrapper = PasskeyToWrapper(old_credentials.GetPasskey(),
+                                                  user_salt, 1);
+
+    VaultKeyset vault_keyset;
+    if (UnwrapMasterKey(user_key_file, passkey_wrapper, &vault_keyset)) {
+      // Save to the next key index first so that if there is a failure, we
+      // don't delete the existing working keyset.
+      bool save_result = SaveVaultKeyset(credentials, vault_keyset, index + 1);
+      if (save_result) {
+        // Saved okay, move to index 0.
+        if (!file_util::ReplaceFile(FilePath(GetUserKeyFile(credentials,
+                                                           index + 1)),
+                                   FilePath(GetUserKeyFile(credentials, 0)))) {
+          return false;
+        }
+        if (!file_util::ReplaceFile(FilePath(GetUserSaltFile(credentials,
+                                                           index + 1)),
+                                   FilePath(GetUserSaltFile(credentials, 0)))) {
+          return false;
+        }
+        // Remove older keys
+        for (index = 1; /* loop forever */; index++) {
+          FilePath old_user_key_file(GetUserKeyFile(old_credentials, index));
+          FilePath old_user_salt_file(GetUserSaltFile(old_credentials, index));
+          if (!file_util::AbsolutePath(&old_user_key_file)) {
+            break;
+          }
+          file_util::Delete(old_user_key_file, false);
+          file_util::Delete(old_user_salt_file, false);
+        }
+        return true;
+      } else {
+        // Couldn't save the vault keyset, delete it
+        file_util::Delete(FilePath(GetUserKeyFile(credentials, index + 1)),
+                          false);
+        file_util::Delete(FilePath(GetUserSaltFile(credentials, index + 1)),
+                          false);
+        return false;
+      }
+    }
+  }
+  return false;
+}
+
+bool Mount::MountIncognitoCryptohome() {
+  // Attempt to mount incognitofs
+  if (mount("incognitofs", home_dir_.c_str(), "tmpfs",
+            kDefaultMountOptions, "")) {
+    LOG(ERROR) << "Cryptohome mount failed: " << errno << " for incognitofs";
+    return false;
+  }
+  if (set_vault_ownership_) {
+    if (chown(home_dir_.c_str(), default_user_, default_group_)) {
+      LOG(ERROR) << "Couldn't change owner (" << default_user_ << ":"
+                 << default_group_ << ") of incognitofs path: "
+                 << home_dir_.c_str();
+      bool was_busy;
+      Unmount(home_dir_.c_str(), false, &was_busy);
+      return false;
+    }
+  }
+  CopySkeleton();
+  return true;
+}
+
+string Mount::GetUserDirectory(const Credentials& credentials) {
+  return StringPrintf("%s/%s",
+                      shadow_root_.c_str(),
+                      credentials.GetObfuscatedUsername(system_salt_).c_str());
+}
+
+string Mount::GetUserSaltFile(const Credentials& credentials, int index) {
+  return StringPrintf("%s/%s/master.%d.salt",
+                      shadow_root_.c_str(),
+                      credentials.GetObfuscatedUsername(system_salt_).c_str(),
+                      index);
+}
+
+string Mount::GetUserKeyFile(const Credentials& credentials, int index) {
+  return StringPrintf("%s/%s/master.%d",
+                      shadow_root_.c_str(),
+                      credentials.GetObfuscatedUsername(system_salt_).c_str(),
+                      index);
+}
+
+string Mount::GetUserVaultPath(const Credentials& credentials) {
+  return StringPrintf("%s/%s/vault",
+                      shadow_root_.c_str(),
+                      credentials.GetObfuscatedUsername(system_salt_).c_str());
+}
+
+void Mount::RecursiveCopy(const FilePath& destination,
+                          const FilePath& source) {
+  file_util::FileEnumerator file_enumerator(source, false,
+                                            file_util::FileEnumerator::FILES);
+  FilePath next_path;
+  while (!(next_path = file_enumerator.Next()).empty()) {
+    FilePath file_name = next_path.BaseName();
+    FilePath destination_file = destination.Append(file_name);
+    file_util::CopyFile(next_path, destination_file);
+    if (set_vault_ownership_) {
+      if (chown(destination_file.value().c_str(), default_user_,
+               default_group_)) {
+        LOG(ERROR) << "Couldn't change owner (" << default_user_ << ":"
+                   << default_group_ << ") of skeleton path: "
+                   << destination_file.value().c_str();
+      }
+    }
+  }
+  file_util::FileEnumerator dir_enumerator(source, false,
+      file_util::FileEnumerator::DIRECTORIES);
+  while (!(next_path = dir_enumerator.Next()).empty()) {
+    FilePath dir_name = next_path.BaseName();
+    FilePath destination_dir = destination.Append(dir_name);
+    file_util::CreateDirectory(destination_dir);
+    if (set_vault_ownership_) {
+      if (chown(destination_dir.value().c_str(), default_user_,
+               default_group_)) {
+        LOG(ERROR) << "Couldn't change owner (" << default_user_ << ":"
+                   << default_group_ << ") of skeleton path: "
+                   << destination_dir.value().c_str();
+      }
+    }
+    RecursiveCopy(destination_dir, next_path);
+  }
+}
+
+void Mount::CopySkeletonForUser(const Credentials& credentials) {
+  if (IsCryptohomeMountedForUser(credentials)) {
+    CopySkeleton();
+  }
+}
+
+void Mount::CopySkeleton() {
+  RecursiveCopy(FilePath(home_dir_), FilePath(skel_source_));
+}
+
+void Mount::GetSecureRandom(unsigned char *rand, int length) const {
+  // TODO(fes): Get assistance from the TPM when it is available
+  // Seed the OpenSSL random number generator until it is happy
+  while (!RAND_status()) {
+    char buffer[256];
+    file_util::ReadFile(FilePath(entropy_source_), buffer, sizeof(buffer));
+    RAND_add(buffer, sizeof(buffer), sizeof(buffer));
+  }
+
+  // Have OpenSSL generate the random bytes
+  RAND_bytes(rand, length);
+}
+
+bool Mount::Unmount(const std::string& path, bool lazy, bool* was_busy) {
+  if (lazy) {
+    // TODO(fes): Place platform-specific calls in a separate class so that
+    // they can be mocked.
+    if (umount2(path.c_str(), MNT_DETACH)) {
+      if (was_busy) {
+        *was_busy = (errno == EBUSY);
+      }
+      return false;
+    }
+  } else {
+    if (umount(path.c_str())) {
+      if (was_busy) {
+        *was_busy = (errno == EBUSY);
+      }
+      return false;
+    }
+  }
+  if (was_busy) {
+    *was_busy = false;
+  }
+  return true;
+}
+
+bool Mount::UnwrapMasterKey(const FilePath& path,
+                            const chromeos::Blob& passkey,
+                            VaultKeyset* vault_keyset) {
+  // TODO(fes): Update this with openssl/tpm_engine or opencryptoki once
+  // available
+  // Load the encrypted master key
+  SecureBlob cipher_text;
+  if (!LoadFileBytes(path, cipher_text)) {
+    LOG(ERROR) << "Unable to read master key file";
+    return false;
+  }
+
+  unsigned int header_size = kOpenSSLMagic.length() + PKCS5_SALT_LEN;
+
+  if (cipher_text.size() < header_size) {
+    LOG(ERROR) << "Master key file too short";
+    return false;
+  }
+
+  // Grab the salt used in converting the passkey to a key (OpenSSL
+  // passkey-encrypted files have the format:
+  // Salted__<8-byte-salt><ciphertext>)
+  unsigned char salt[PKCS5_SALT_LEN];
+  memcpy(salt, &cipher_text[kOpenSSLMagic.length()], PKCS5_SALT_LEN);
+
+  cipher_text.erase(cipher_text.begin(), cipher_text.begin() + header_size);
+
+  unsigned char wrapper_key[EVP_MAX_KEY_LENGTH];
+  unsigned char iv[EVP_MAX_IV_LENGTH];
+
+  // Convert the passkey to a key encryption key
+  if (!EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha1(), salt, &passkey[0],
+                          passkey.size(), 1, wrapper_key, iv)) {
+    LOG(ERROR) << "Failure converting bytes to key";
+    return false;
+  }
+
+  SecureBlob plain_text(cipher_text.size());
+
+  int final_size = 0;
+  int decrypt_size = plain_text.size();
+
+  // Do the actual decryption
+  EVP_CIPHER_CTX d_ctx;
+  EVP_CIPHER_CTX_init(&d_ctx);
+  EVP_DecryptInit_ex(&d_ctx, EVP_aes_256_ecb(), NULL, wrapper_key, iv);
+  if (!EVP_DecryptUpdate(&d_ctx, &plain_text[0], &decrypt_size,
+                        &cipher_text[0],
+                        cipher_text.size())) {
+    LOG(ERROR) << "DecryptUpdate failed";
+    return false;
+  }
+  if (!EVP_DecryptFinal_ex(&d_ctx, &plain_text[decrypt_size], &final_size)) {
+    unsigned long err = ERR_get_error();
+    ERR_load_ERR_strings();
+    ERR_load_crypto_strings();
+
+    LOG(ERROR) << "DecryptFinal Error: " << err
+               << ": " << ERR_lib_error_string(err)
+               << ", " << ERR_func_error_string(err)
+               << ", " << ERR_reason_error_string(err);
+
+    return false;
+  }
+  final_size += decrypt_size;
+
+  plain_text.resize(final_size);
+
+  if (plain_text.size() != VaultKeyset::SerializedSize()) {
+    LOG(ERROR) << "Plain text was not the correct size: " << plain_text.size()
+               << ", expected: " << VaultKeyset::SerializedSize();
+    return false;
+  }
+
+  (*vault_keyset).AssignBuffer(plain_text);
+
+  return true;
+}
+
+bool Mount::CreateMasterKey(const Credentials& credentials, int index) {
+  VaultKeyset vault_keyset;
+  vault_keyset.CreateRandom(*this);
+  return SaveVaultKeyset(credentials, vault_keyset, index);
+}
+
+bool Mount::SaveVaultKeyset(const Credentials& credentials,
+                            const VaultKeyset& vault_keyset,
+                            int index) {
+  unsigned char wrapper_key[EVP_MAX_KEY_LENGTH];
+  unsigned char iv[EVP_MAX_IV_LENGTH];
+  unsigned char salt[PKCS5_SALT_LEN];
+
+  // Create a salt for this master key
+  GetSecureRandom(salt, sizeof(salt));
+  SecureBlob user_salt = GetUserSalt(credentials, index, true);
+
+  // Convert the passkey to a passkey wrapper
+  SecureBlob passkey_wrapper =
+      PasskeyToWrapper(credentials.GetPasskey(), user_salt, 1);
+
+  // Convert the passkey wrapper to a key encryption key
+  if (!EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha1(), salt, &passkey_wrapper[0],
+                          passkey_wrapper.size(), 1, wrapper_key, iv)) {
+    LOG(ERROR) << "Failure converting bytes to key";
+    return false;
+  }
+
+  SecureBlob keyset_blob = vault_keyset.ToBuffer();
+
+  // Store the salt and encrypt the master key
+  unsigned int header_size = kOpenSSLMagic.length() + PKCS5_SALT_LEN;
+  SecureBlob cipher_text(header_size
+                         + keyset_blob.size()
+                         + EVP_CIPHER_block_size(EVP_aes_256_ecb()));
+  memcpy(&cipher_text[0], kOpenSSLMagic.c_str(), kOpenSSLMagic.length());
+  memcpy(&cipher_text[kOpenSSLMagic.length()], salt, PKCS5_SALT_LEN);
+
+  int current_size = header_size;
+  int encrypt_size = 0;
+  EVP_CIPHER_CTX e_ctx;
+  EVP_CIPHER_CTX_init(&e_ctx);
+
+  // Encrypt the keyset
+  EVP_EncryptInit_ex(&e_ctx, EVP_aes_256_ecb(), NULL, wrapper_key, iv);
+  if (!EVP_EncryptUpdate(&e_ctx, &cipher_text[current_size], &encrypt_size,
+                         &keyset_blob[0],
+                         keyset_blob.size())) {
+    LOG(ERROR) << "EncryptUpdate failed";
+    return false;
+  }
+  current_size += encrypt_size;
+  encrypt_size = 0;
+
+  // Finish the encryption
+  if (!EVP_EncryptFinal_ex(&e_ctx, &cipher_text[current_size], &encrypt_size)) {
+    LOG(ERROR) << "EncryptFinal failed";
+    return false;
+  }
+  current_size += encrypt_size;
+  cipher_text.resize(current_size);
+
+  chromeos::SecureMemset(wrapper_key, sizeof(wrapper_key), 0);
+
+  // Save the master key
+  unsigned int data_written = file_util::WriteFile(
+      FilePath(GetUserKeyFile(credentials, index)),
+      reinterpret_cast<const char*>(&cipher_text[0]),
+      cipher_text.size());
+
+  if (data_written != cipher_text.size()) {
+    LOG(ERROR) << "Write to master key failed";
+    return false;
+  }
+  return true;
+}
+
+SecureBlob Mount::PasskeyToWrapper(const chromeos::Blob& passkey,
+                              const chromeos::Blob& salt, int iters) {
+  // TODO(fes): Update this when TPM support is available, or use a memory-
+  // bound strengthening algorithm.
+  int update_length = passkey.size();
+  SecureBlob holder(CRYPTOHOME_MAX(update_length, SHA_DIGEST_LENGTH));
+  memcpy(&holder[0], &passkey[0], update_length);
+
+  // Repeatedly hash the user passkey and salt to generate the wrapper
+  for (int i = 0; i < iters; ++i) {
+    SHA_CTX ctx;
+    unsigned char md_value[SHA_DIGEST_LENGTH];
+
+    SHA1_Init(&ctx);
+    SHA1_Update(&ctx, &salt[0], salt.size());
+    SHA1_Update(&ctx, &holder[0], update_length);
+    SHA1_Final(md_value, &ctx);
+
+    memcpy(&holder[0], md_value, SHA_DIGEST_LENGTH);
+    update_length = SHA_DIGEST_LENGTH;
+  }
+
+  holder.resize(update_length);
+  SecureBlob wrapper(update_length * 2);
+  AsciiEncodeToBuffer(holder, reinterpret_cast<char*>(&wrapper[0]),
+                      wrapper.size());
+  return wrapper;
+}
+
+SecureBlob Mount::GetSystemSalt() {
+  return system_salt_;
+}
+
+SecureBlob Mount::GetUserSalt(const Credentials& credentials, int index,
+                              bool force) {
+  FilePath path(GetUserSaltFile(credentials, index));
+  return GetOrCreateSalt(path, CRYPTOHOME_DEFAULT_SALT_LENGTH, force);
+}
+
+SecureBlob Mount::GetOrCreateSalt(const FilePath& path, int length,
+                                  bool force) {
+  SecureBlob salt;
+  if (force || !file_util::PathExists(path)) {
+    // If this salt doesn't exist, automatically create it
+    salt.resize(length);
+    GetSecureRandom(&salt[0], salt.size());
+    int data_written = file_util::WriteFile(path,
+        reinterpret_cast<const char*>(&salt[0]),
+        length);
+    if (data_written != length) {
+      LOG(ERROR) << "Could not write user salt";
+      return SecureBlob();
+    }
+  } else {
+    // Otherwise just load the contents of the salt
+    int64 file_size;
+    if (!file_util::GetFileSize(path, &file_size)) {
+      LOG(ERROR) << "Could not get size of " << path.value();
+      return SecureBlob();
+    }
+    if (file_size > INT_MAX) {
+      LOG(ERROR) << "File " << path.value() << " is too large: " << file_size;
+      return SecureBlob();
+    }
+    salt.resize(file_size);
+    int data_read = file_util::ReadFile(path, reinterpret_cast<char*>(&salt[0]),
+                                        file_size);
+    if (data_read != file_size) {
+      LOG(ERROR) << "Could not read entire file " << file_size;
+      return SecureBlob();
+    }
+  }
+  return salt;
+}
+
+void Mount::AsciiEncodeToBuffer(const chromeos::Blob& blob, char* buffer,
+                              int buffer_length) {
+  const char hex_chars[] = "0123456789abcdef";
+  int i = 0;
+  for (chromeos::Blob::const_iterator it = blob.begin();
+      it < blob.end() && (i + 1) < buffer_length; ++it) {
+    buffer[i++] = hex_chars[((*it) >> 4) & 0x0f];
+    buffer[i++] = hex_chars[(*it) & 0x0f];
+  }
+  if (i < buffer_length) {
+    buffer[i] = '\0';
+  }
+}
+
+bool Mount::AddKeyToEcryptfsKeyring(const VaultKeyset& vault_keyset,
+                                    string* key_signature,
+                                    string* fnek_signature) {
+  // Clear the user keyring
+  keyctl(KEYCTL_CLEAR, KEY_SPEC_USER_KEYRING);
+
+  // Add the FEK
+  *key_signature = chromeos::AsciiEncode(vault_keyset.FEK_SIG());
+  if (!PushVaultKey(vault_keyset.FEK(), *key_signature,
+                    vault_keyset.FEK_SALT())) {
+    LOG(ERROR) << "Couldn't add ecryptfs key to keyring";
+    return false;
+  }
+
+  // Add the FNEK
+  *fnek_signature = chromeos::AsciiEncode(vault_keyset.FNEK_SIG());
+  if (!PushVaultKey(vault_keyset.FNEK(), *fnek_signature,
+                    vault_keyset.FNEK_SALT())) {
+    LOG(ERROR) << "Couldn't add ecryptfs fnek key to keyring";
+    return false;
+  }
+
+  return true;
+}
+
+bool Mount::PushVaultKey(const SecureBlob& key, const std::string& key_sig,
+                         const SecureBlob& salt) {
+  DCHECK(key.size() == ECRYPTFS_MAX_KEY_BYTES);
+  DCHECK(key_sig.length() == (ECRYPTFS_SIG_SIZE * 2));
+  DCHECK(salt.size() == ECRYPTFS_SALT_SIZE);
+
+  struct ecryptfs_auth_tok auth_token;
+
+  generate_payload(&auth_token, const_cast<char*>(key_sig.c_str()),
+                   const_cast<char*>(reinterpret_cast<const char*>(&salt[0])),
+                   const_cast<char*>(reinterpret_cast<const char*>(&key[0])));
+
+  if (ecryptfs_add_auth_tok_to_keyring(&auth_token,
+      const_cast<char*>(key_sig.c_str())) < 0) {
+    LOG(ERROR) << "PushVaultKey failed";
+  }
+
+  return true;
+}
+
+bool Mount::LoadFileBytes(const FilePath& path,
+                          SecureBlob& blob) {
+  int64 file_size;
+  if (!file_util::PathExists(path)) {
+    LOG(ERROR) << path.value() << " does not exist!";
+    return false;
+  }
+  if (!file_util::GetFileSize(path, &file_size)) {
+    LOG(ERROR) << "Could not get size of " << path.value();
+    return false;
+  }
+  if (file_size > INT_MAX) {
+    LOG(ERROR) << "File " << path.value() << " is too large: " << file_size;
+    return false;
+  }
+  SecureBlob buf(file_size);
+  int data_read = file_util::ReadFile(path, reinterpret_cast<char*>(&buf[0]),
+                                      file_size);
+  // Cast is okay because of comparison to INT_MAX above
+  if (data_read != static_cast<int>(file_size)) {
+    LOG(ERROR) << "Could not read entire file " << file_size;
+    return false;
+  }
+  blob.swap(buf);
+  return true;
+}
+
+bool Mount::TerminatePidsWithOpenFiles(const std::string& path, bool hard) {
+  std::vector<pid_t> pids = LookForOpenFiles(path);
+  for (std::vector<pid_t>::iterator it = pids.begin(); it != pids.end(); it++) {
+    pid_t pid = static_cast<pid_t>(*it);
+    if (pid != getpid()) {
+      if (hard) {
+        kill(pid, SIGTERM);
+      } else {
+        kill(pid, SIGKILL);
+      }
+    }
+  }
+  return (pids.size() != 0);
+}
+
+std::vector<pid_t> Mount::LookForOpenFiles(const std::string& path_in) {
+  // Make sure that if we get a directory, it has a trailing separator
+  FilePath file_path(path_in);
+  file_util::EnsureEndsWithSeparator(&file_path);
+  std::string path = file_path.value();
+
+  std::vector<pid_t> pids;
+
+  // Open /proc
+  DIR* proc_dir = opendir(kProcDir.c_str());
+
+  if (!proc_dir) {
+    return pids;
+  }
+
+  int linkbuf_length = path.length();
+  std::vector<char> linkbuf(linkbuf_length);
+
+  // List PIDs in /proc
+  while (struct dirent* pid_dirent = readdir(proc_dir)) {
+    pid_t pid = static_cast<pid_t>(atoi(pid_dirent->d_name));
+    // Ignore PID 1 and errors
+    if (pid <= 1) {
+      continue;
+    }
+    // Open /proc/<pid>/fd
+    std::string fd_dirname = StringPrintf("%s/%d/fd", kProcDir.c_str(), pid);
+    DIR* fd_dir = opendir(fd_dirname.c_str());
+    if (!fd_dir) {
+      continue;
+    }
+
+    // List open file descriptors
+    while (struct dirent* fd_dirent = readdir(fd_dir)) {

[mschilder, 2010/05/27 04:20:18]

readdir_r()?

+      std::string fd_path = StringPrintf("%s/%s", fd_dirname.c_str(),
+                                         fd_dirent->d_name);
+      ssize_t link_length = readlink(fd_path.c_str(), &linkbuf[0],
+                                     linkbuf.size());
+      if (link_length > 0) {
+        std::string open_file(&linkbuf[0], link_length);
+        if (open_file.length() >= path.length()) {
+          if (open_file.substr(0, path.length()).compare(path) == 0) {
+            pids.push_back(pid);
+            break;
+          }
+        }
+      }
+    }
+
+    closedir(fd_dir);
+  }
+
+  closedir(proc_dir);
+
+  return pids;
+}
+
+bool Mount::TerminatePidsForUser(const uid_t uid, bool hard) {
+  std::vector<pid_t> pids = GetPidsForUser(uid);
+  for (std::vector<pid_t>::iterator it = pids.begin(); it != pids.end(); it++) {
+    pid_t pid = static_cast<pid_t>(*it);
+    if (pid != getpid()) {
+      if (hard) {
+        kill(pid, SIGTERM);
+      } else {
+        kill(pid, SIGKILL);
+      }
+    }
+  }
+  return (pids.size() != 0);
+}
+
+// TODO(fes): Pull this into a separate helper class
+std::vector<pid_t> Mount::GetPidsForUser(uid_t uid) {
+  std::vector<pid_t> pids;
+
+  // Open /proc
+  DIR* proc_dir = opendir(kProcDir.c_str());
+
+  if (!proc_dir) {
+    return pids;
+  }
+
+  // List PIDs in /proc
+  while (struct dirent* pid_dirent = readdir(proc_dir)) {
+    pid_t pid = static_cast<pid_t>(atoi(pid_dirent->d_name));
+    if (pid <= 0) {
+      continue;
+    }
+    // Open /proc/<pid>/status
+    std::string stat_path = StringPrintf("%s/%d/status", kProcDir.c_str(),
+                                         pid);
+    string contents;
+    if (!file_util::ReadFileToString(FilePath(stat_path), &contents)) {
+      continue;
+    }
+
+    size_t uid_loc = contents.find("Uid:");
+    if (!uid_loc) {
+      continue;
+    }
+    uid_loc += 4;
+
+    size_t uid_end = contents.find("\n", uid_loc);
+    if (!uid_end) {
+      continue;
+    }
+
+    contents = contents.substr(uid_loc, uid_end - uid_loc);
+
+    std::vector<std::string> tokens;
+    Tokenize(contents, " \t", &tokens);
+
+    for (std::vector<std::string>::iterator it = tokens.begin();
+        it != tokens.end(); it++) {
+      std::string& value = *it;
+      if (value.length() == 0) {
+        continue;
+      }
+      uid_t check_uid = static_cast<uid_t>(atoi(value.c_str()));
+      if (check_uid == uid) {
+        pids.push_back(pid);
+        break;
+      }
+    }
+  }
+
+  closedir(proc_dir);
+
+  return pids;
+}
+
+} // cryptohome