linux-kernel - [PATCH] f2fs: don't allow rename unencrypted file to encrypted directory

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Date:   Wed, 8 Mar 2017 20:08:20 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        Chao Yu <yuchao0@...wei.com>
Subject: [PATCH] f2fs: don't allow rename unencrypted file to encrypted directory

In commit d9cdc9033181 ("ext4 crypto: enforce context consistency") we
declared that:

2) All files or directories in a directory must be protected using the
    same key as their containing directory.

But in f2fs_cross_rename there is a vulnerability that allow to cross
rename unencrypted file into encrypted directory, it needs to be refused.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 fs/f2fs/namei.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 25c073f6c7d4..8de684b84cb9 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -855,6 +855,10 @@ static int f2fs_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
 			!fscrypt_has_encryption_key(new_dir)))
 		return -ENOKEY;
 
+	if (f2fs_encrypted_inode(old_dir) && !f2fs_encrypted_inode(new_inode) ||
+		f2fs_encrypted_inode(new_dir) && !f2fs_encrypted_inode(old_inode))
+		return -EPERM;
+
 	if ((f2fs_encrypted_inode(old_dir) || f2fs_encrypted_inode(new_dir)) &&
 			(old_dir != new_dir) &&
 			(!fscrypt_has_permitted_context(new_dir, old_inode) ||
-- 
2.8.2.295.g3f1c1d0