From 63136858aecbe86dbd3c3289a3f46ba1b5f92239 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 23 Jun 2017 19:48:44 -0400 Subject: [PATCH] ext4: require key for truncate(2) of encrypted file Currently, filesystems allow truncate(2) on an encrypted file without the encryption key. However, it's impossible to correctly handle the case where the size being truncated to is not a multiple of the filesystem block size, because that would require decrypting the final block, zeroing the part beyond i_size, then encrypting the block. As other modifications to encrypted file contents are prohibited without the key, just prohibit truncate(2) as well, making it fail with ENOKEY. Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o --- fs/ext4/inode.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 754c2190af31..daed9b38362a 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5323,6 +5323,14 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) loff_t oldsize = inode->i_size; int shrink = (attr->ia_size <= inode->i_size); + if (ext4_encrypted_inode(inode)) { + error = fscrypt_get_encryption_info(inode); + if (error) + return error; + if (!fscrypt_has_encryption_key(inode)) + return -ENOKEY; + } + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); -- 2.20.1