+ struct key *key;
+ const struct fscrypt_key *payload;
+ int err;
+
+ key = find_and_lock_process_key(FS_KEY_DESC_PREFIX,
+ ctx->master_key_descriptor,
+ mode->keysize, &payload);
+ if (key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
+ key = find_and_lock_process_key(inode->i_sb->s_cop->key_prefix,
+ ctx->master_key_descriptor,
+ mode->keysize, &payload);
+ }
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+
+ if (ctx->flags & FS_POLICY_FLAG_DIRECT_KEY) {
+ if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) {
+ fscrypt_warn(inode->i_sb,
+ "direct key mode not allowed with %s",
+ mode->friendly_name);
+ err = -EINVAL;
+ } else if (ctx->contents_encryption_mode !=
+ ctx->filenames_encryption_mode) {
+ fscrypt_warn(inode->i_sb,
+ "direct key mode not allowed with different contents and filenames modes");
+ err = -EINVAL;
+ } else {
+ memcpy(derived_key, payload->raw, mode->keysize);
+ err = 0;
+ }
+ } else {
+ err = derive_key_aes(payload->raw, ctx, derived_key,
+ mode->keysize);
+ }
+ up_read(&key->sem);
+ key_put(key);
+ return err;
+}
+
+/* Allocate and key a symmetric cipher object for the given encryption mode */
+static struct crypto_skcipher *
+allocate_skcipher_for_mode(struct fscrypt_mode *mode, const u8 *raw_key,
+ const struct inode *inode)
+{
+ struct crypto_skcipher *tfm;
+ int err;
+
+ tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);
+ if (IS_ERR(tfm)) {
+ fscrypt_warn(inode->i_sb,
+ "error allocating '%s' transform for inode %lu: %ld",
+ mode->cipher_str, inode->i_ino, PTR_ERR(tfm));
+ return tfm;
+ }
+ if (unlikely(!mode->logged_impl_name)) {
+ /*
+ * fscrypt performance can vary greatly depending on which
+ * crypto algorithm implementation is used. Help people debug
+ * performance problems by logging the ->cra_driver_name the
+ * first time a mode is used. Note that multiple threads can
+ * race here, but it doesn't really matter.
+ */
+ mode->logged_impl_name = true;
+ pr_info("fscrypt: %s using implementation \"%s\"\n",
+ mode->friendly_name,
+ crypto_skcipher_alg(tfm)->base.cra_driver_name);
+ }
+ crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+ err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);
+ if (err)
+ goto err_free_tfm;
+
+ return tfm;
+
+err_free_tfm:
+ crypto_free_skcipher(tfm);
+ return ERR_PTR(err);
+}
+
+/* Master key referenced by FS_POLICY_FLAG_DIRECT_KEY policy */
+struct fscrypt_master_key {
+ struct hlist_node mk_node;
+ refcount_t mk_refcount;
+ const struct fscrypt_mode *mk_mode;
+ struct crypto_skcipher *mk_ctfm;
+ u8 mk_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+ u8 mk_raw[FS_MAX_KEY_SIZE];
+};
+
+static void free_master_key(struct fscrypt_master_key *mk)
+{
+ if (mk) {
+ crypto_free_skcipher(mk->mk_ctfm);
+ kzfree(mk);
+ }
+}
+
+static void put_master_key(struct fscrypt_master_key *mk)
+{
+ if (!refcount_dec_and_lock(&mk->mk_refcount, &fscrypt_master_keys_lock))