linux-kernel - [PATCH 4.9 101/138] fscrypt: use ENOKEY when file cannot be created w/o key

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Date:   Tue, 28 Nov 2017 11:23:22 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>,
        Theodore Tso <tytso@....edu>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 101/138] fscrypt: use ENOKEY when file cannot be created w/o key

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>


[ Upstream commit 54475f531bb8d7078f63c159e5e0615d486c498c ]

As part of an effort to clean up fscrypt-related error codes, make
attempting to create a file in an encrypted directory that hasn't been
"unlocked" fail with ENOKEY.  Previously, several error codes were used
for this case, including ENOENT, EACCES, and EPERM, and they were not
consistent between and within filesystems.  ENOKEY is a better choice
because it expresses that the failure is due to lacking the encryption
key.  It also matches the error code returned when trying to open an
encrypted regular file without the key.

I am not aware of any users who might be relying on the previous
inconsistent error codes, which were never documented anywhere.

This failure case will be exercised by an xfstest.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/crypto/fname.c |    4 ++--
 fs/ext4/ialloc.c  |    2 +-
 fs/ext4/namei.c   |    4 +++-
 fs/f2fs/dir.c     |    5 ++++-
 fs/f2fs/namei.c   |    4 ++--
 5 files changed, 12 insertions(+), 7 deletions(-)

--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -332,7 +332,7 @@ int fscrypt_fname_usr_to_disk(struct ino
 	 * in a directory. Consequently, a user space name cannot be mapped to
 	 * a disk-space name
 	 */
-	return -EACCES;
+	return -ENOKEY;
 }
 EXPORT_SYMBOL(fscrypt_fname_usr_to_disk);
 
@@ -367,7 +367,7 @@ int fscrypt_setup_filename(struct inode
 		return 0;
 	}
 	if (!lookup)
-		return -EACCES;
+		return -ENOKEY;
 
 	/*
 	 * We don't have the key and we are doing a lookup; decode the
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -771,7 +771,7 @@ struct inode *__ext4_new_inode(handle_t
 		if (err)
 			return ERR_PTR(err);
 		if (!fscrypt_has_encryption_key(dir))
-			return ERR_PTR(-EPERM);
+			return ERR_PTR(-ENOKEY);
 		if (!handle)
 			nblocks += EXT4_DATA_TRANS_BLOCKS(dir->i_sb);
 		encrypt = 1;
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1378,6 +1378,8 @@ static struct buffer_head * ext4_find_en
 		return NULL;
 
 	retval = ext4_fname_setup_filename(dir, d_name, 1, &fname);
+	if (retval == -ENOENT)
+		return NULL;
 	if (retval)
 		return ERR_PTR(retval);
 
@@ -3090,7 +3092,7 @@ static int ext4_symlink(struct inode *di
 		if (err)
 			return err;
 		if (!fscrypt_has_encryption_key(dir))
-			return -EPERM;
+			return -ENOKEY;
 		disk_link.len = (fscrypt_fname_encrypted_size(dir, len) +
 				 sizeof(struct fscrypt_symlink_data));
 		sd = kzalloc(disk_link.len, GFP_KERNEL);
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -277,7 +277,10 @@ struct f2fs_dir_entry *f2fs_find_entry(s
 
 	err = fscrypt_setup_filename(dir, child, 1, &fname);
 	if (err) {
-		*res_page = ERR_PTR(err);
+		if (err == -ENOENT)
+			*res_page = NULL;
+		else
+			*res_page = ERR_PTR(err);
 		return NULL;
 	}
 
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -403,7 +403,7 @@ static int f2fs_symlink(struct inode *di
 			return err;
 
 		if (!fscrypt_has_encryption_key(dir))
-			return -EPERM;
+			return -ENOKEY;
 
 		disk_link.len = (fscrypt_fname_encrypted_size(dir, len) +
 				sizeof(struct fscrypt_symlink_data));
@@ -447,7 +447,7 @@ static int f2fs_symlink(struct inode *di
 			goto err_out;
 
 		if (!fscrypt_has_encryption_key(inode)) {
-			err = -EPERM;
+			err = -ENOKEY;
 			goto err_out;
 		}