Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux

Pull fscrypt update from Eric Biggers:
 "Add support for 'hardware-wrapped inline encryption keys' to fscrypt.

  When enabled on supported platforms, this feature protects file
  contents keys from certain attacks, such as cold boot attacks.

  This feature uses the block layer support for wrapped keys which was
  merged in 6.15. Wrapped key support has existed out-of-tree in Android
  for a long time, and it's finally ready for upstream now that there is
  a platform on which it works end-to-end with upstream.

  Specifically, it works on the Qualcomm SM8650 HDK, using the Qualcomm
  ICE (Inline Crypto Engine) and HWKM (Hardware Key Manager). The
  corresponding driver support is included in the SCSI tree for 6.16.

  Validation for this feature includes two new tests that were already
  merged into xfstests (generic/368 and generic/369)"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
  fscrypt: add support for hardware-wrapped keys

1 files changed, 38 insertions, 6 deletions

diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index 7fa53d30aec30..1d008c440cb69 100644
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -89,7 +89,8 @@ static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode,
 }
 
 /* Enable inline encryption for this file if supported. */
-int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci)
+int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci,
+				   bool is_hw_wrapped_key)
 {
 	const struct inode *inode = ci->ci_inode;
 	struct super_block *sb = inode->i_sb;
@@ -130,7 +131,8 @@ int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci)
 	crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode;
 	crypto_cfg.data_unit_size = 1U << ci->ci_data_unit_bits;
 	crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
-	crypto_cfg.key_type = BLK_CRYPTO_KEY_TYPE_RAW;
+	crypto_cfg.key_type = is_hw_wrapped_key ?
+		BLK_CRYPTO_KEY_TYPE_HW_WRAPPED : BLK_CRYPTO_KEY_TYPE_RAW;
 
 	devs = fscrypt_get_devices(sb, &num_devs);
 	if (IS_ERR(devs))
@@ -151,12 +153,15 @@ out_free_devs:
 }
 
 int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
-				     const u8 *raw_key,
+				     const u8 *key_bytes, size_t key_size,
+				     bool is_hw_wrapped,
 				     const struct fscrypt_inode_info *ci)
 {
 	const struct inode *inode = ci->ci_inode;
 	struct super_block *sb = inode->i_sb;
 	enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode;
+	enum blk_crypto_key_type key_type = is_hw_wrapped ?
+		BLK_CRYPTO_KEY_TYPE_HW_WRAPPED : BLK_CRYPTO_KEY_TYPE_RAW;
 	struct blk_crypto_key *blk_key;
 	struct block_device **devs;
 	unsigned int num_devs;
@@ -167,9 +172,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
 	if (!blk_key)
 		return -ENOMEM;
 
-	err = blk_crypto_init_key(blk_key, raw_key, ci->ci_mode->keysize,
-				  BLK_CRYPTO_KEY_TYPE_RAW, crypto_mode,
-				  fscrypt_get_dun_bytes(ci),
+	err = blk_crypto_init_key(blk_key, key_bytes, key_size, key_type,
+				  crypto_mode, fscrypt_get_dun_bytes(ci),
 				  1U << ci->ci_data_unit_bits);
 	if (err) {
 		fscrypt_err(inode, "error %d initializing blk-crypto key", err);
@@ -228,6 +232,34 @@ void fscrypt_destroy_inline_crypt_key(struct super_block *sb,
 	kfree_sensitive(blk_key);
 }
 
+/*
+ * Ask the inline encryption hardware to derive the software secret from a
+ * hardware-wrapped key.  Returns -EOPNOTSUPP if hardware-wrapped keys aren't
+ * supported on this filesystem or hardware.
+ */
+int fscrypt_derive_sw_secret(struct super_block *sb,
+			     const u8 *wrapped_key, size_t wrapped_key_size,
+			     u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE])
+{
+	int err;
+
+	/* The filesystem must be mounted with -o inlinecrypt. */
+	if (!(sb->s_flags & SB_INLINECRYPT)) {
+		fscrypt_warn(NULL,
+			     "%s: filesystem not mounted with inlinecrypt\n",
+			     sb->s_id);
+		return -EOPNOTSUPP;
+	}
+
+	err = blk_crypto_derive_sw_secret(sb->s_bdev, wrapped_key,
+					  wrapped_key_size, sw_secret);
+	if (err == -EOPNOTSUPP)
+		fscrypt_warn(NULL,
+			     "%s: block device doesn't support hardware-wrapped keys\n",
+			     sb->s_id);
+	return err;
+}
+
 bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
 {
 	return inode->i_crypt_info->ci_inlinecrypt;