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

Pull fscrypt fixes from Eric Biggers:

 - Add more checks to prevent encryption on "large block size" ext4
   filesystems (s_blocksize > PAGE_SIZE), which isn't supported yet.
   There was already a mount-time check, but it wasn't enough.

 - Add missing memory barrier to fscrypt_find_mode_key()

 - Add missing zeroization in an error path

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
  ext4: reject encrypted inodes when block size > page size
  ext4: refuse encryption when block size > page size
  fscrypt: Fix missing barrier in fscrypt_find_mode_key()
  fscrypt: Explicitly zeroize sw_secret in error path

4 files changed, 25 insertions, 2 deletions

diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 874cc183ee62..09364fddcb7a 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -561,8 +561,10 @@ static int add_master_key(struct super_block *sb,
 		if (secret->is_hw_wrapped) {
 			err = fscrypt_derive_sw_secret(sb, secret->bytes,
 						       secret->size, sw_secret);
-			if (err)
+			if (err) {
+				memzero_explicit(sw_secret, sizeof(sw_secret));
 				return err;
+			}
 			kdf_key = sw_secret;
 			kdf_key_size = sizeof(sw_secret);
 			/*
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 892044ebcaca..a77b889d7578 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -205,8 +205,14 @@ fscrypt_find_mode_key(struct fscrypt_master_key *mk, u8 hkdf_context,
 		if (node->hkdf_context == hkdf_context &&
 		    node->mode_num == mode_num &&
 		    node->data_unit_bits == ci->ci_data_unit_bits &&
-		    fscrypt_is_key_prepared(&node->key, ci))
+		    fscrypt_is_key_prepared(&node->key, ci)) {
+			/*
+			 * Upgrade the RCU dereference to a full ACQUIRE, so
+			 * that blk-crypto global state is seen as initialized.
+			 */
+			smp_acquire__after_ctrl_dep();
 			return &node->key;
+		}
 	}
 	return NULL;
 }
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 1a0fccb084ef..318b2eaea741 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -156,6 +156,15 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX))
 		return -EOPNOTSUPP;
 
+	/*
+	 * Encryption is not supported when the block size is larger
+	 * than the page size.  This is rejected at mount time by
+	 * ext4_check_large_folio(), and this check here is for the case
+	 * when the 'encrypt' feature is enabled on a mounted filesystem.
+	 */
+	if (inode->i_sb->s_blocksize > PAGE_SIZE)
+		return -EOPNOTSUPP;
+
 	res = ext4_convert_inline_data(inode);
 	if (res)
 		return res;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index b4d581aa5ee1..10cd85d4c721 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6571,6 +6571,12 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 		ret = -EFSCORRUPTED;
 		goto bad_inode;
 	}
+	if (IS_ENCRYPTED(inode) && sb->s_blocksize > PAGE_SIZE) {
+		ext4_error_inode(inode, function, line, 0,
+				 "encrypted inode with block size larger than page size");
+		ret = -EFSCORRUPTED;
+		goto bad_inode;
+	}
 
 	ext4_set_inode_mapping_order(inode);